Impacts of land use change on landscape patterns in mountain human settlement: The case study of Hantai District(Shaanxi,China)

Mountain area is an important geographical unit of land,and its ecology is sensitive and fragile.Over the past few decades,human activities have caused dramatic changes in land use in mountainous areas,which caused changes in landscape patterns and impacts on the ecological environment.It is unknown how the mechanism of land use affects the landscape pattern at different scales.The Hantai District,a typical human settlement in the mountain area in Shaanxi,China,was chosen as the study area.Based on the remote sensing images,the mathematical models and landscape indexes were adopted to evaluate the impact of land use change from 1998 to 2017 on the landscape pattern at different scales,and its main driving forces were analyzed.The results showed that the urbanized land expanded largest from 15.39%to 24.30%,and cultivated land experienced the largest decline from 43.54%to 35.35%.Changes in land use have made the patch morphology of most land types developed from a natural random to a sawtooth shape,and its spatial pattern evolved from a ruleset to a fragmented expansion.This reflects the continuous strengthening of human intervention in the process of regional development.Under the jurisdiction of Hantai District,the biggest change in landscape pattern is in Hanzhong City and Qili Town.The improved economy and increasing population and urbanization rate were the main factors that cause these changes.This research could provide necessary information for understanding the evolution mechanism of land resources in mountainous human settlements for mountainous areas with significant geomorphic differentiation.     

房地产宏观政策期待加大执行力

4月27日,中国社会科学院城市发展与环境研究中心和社会科学文献出版社联合主办的2007年中国房地产高峰论坛暨《 房地产蓝皮书》2007年版出版发布会在北京举行.来自中国社会科学院、国土资源部、建设部、国家统计局、中国房地产协会等部门的专家、学者和官员出席了会议.     

边城廿八都

浙西南的江山市廿八都镇,地处浙闽赣三省交界。四面群山拱卫,仙霞古道穿镇而过,自古有“东南锁钥,入闽咽喉”之称。小镇类似文学家沈从文笔下的边城,当时“也有商人落脚的客店,坐镇不动的理发馆。此外,饭店、杂货铺、油行、盐栈、花衣庄,莫不各有一种地位,装点这条小河街。”而唐宋古道驿站遗址和明清古桥民居至今尚存。     

"一户一宅"的思考

《土地管理法》第六十二条规定,农村村民一户只能拥有一处宅基地。这对于节约集约用地,强化农村宅基地管理具有十分重要的指导意义。长期以来,农村旧的宅基地管理模式造成农村村民住房严重超标,一户多宅以及空心村的现象普遍存在,农村宅基地极度浪费。“一户一宅”制从当前全国农村的实际出发,对农村宅基地使用作出了科学合理的界定。但是,在执行“一户一宅”过程中,也出现一些新情况新问题,在市场经济条件下,这些新情况新问题必须在立法和实践中加以解决,并不断完善现有的制度,以达到科学合理地利用农村土地。     

Influence of the roots of mixed-planting species on the shear strength of saline loess soil

In order to improve our knowledge of the mechanical effect of the roots of mixed-plantings on soil reinforcement and slope protection,the influence of roots of a mixed-planting with four herb species(Medicago sativa L.,Elymus nutans Griseb.,Puccinellia distanx(L.),and Poa pratensis L.)and one shrub species(Caragana korshinskii Kom.)were investigated on the shear strength characteristics of saline loess soil.The root distribution characteristics were assessed via a survey when the plants grew for one year.The effects of the root biomass density,the root mass ratio(RMR)of the fine roots to the coarse roots,the moisture content,and the salt content on the shear strength index of the rooted soil were analyzed via a triaxial compression test,and the mechanism of these effects was discussed.The results indicate that the biomass density decreased linearly with increasing depth.The RMR initially decreased with depth and then increased,exhibiting in a quadratic relationship.The cohesion of the rooted soil increased linearly as the biomass density increased.The cohesion of the rooted soil initially increased with increasing RMR and salt content,and then it decreased.The turning point of the cohesion occurred when the RMR was 0.6 and the salt content was 1.18%.The internal friction angle of the rooted soil initially increased with biomass density and then decreased,and the turning point of the internal friction angle occurred when the biomass density was 0.015 g/cm3.The relationships between the internal friction angle of the rooted soil and the RMR and salt content were exponential incremental and linear subtractive relationship,respectively.Both the cohesion and the internal friction angle of the rooted soil linearly decreased with increasing moisture content.     

Combined Bearing Capacity of Spudcans on a Double Layer Deposit of Strong-Over-Weak Clays

An extreme sea storm process can lead to a jack-up rig under the combined loading condition of vertical load(V), horizontal load(H), and moment(M) to have stability problems. This paper presents the analysis of combined bearing capacities of a circular spudcan on layered clays with a strong layer overlying a comparatively weaker layer. Numerical models combined with displacement-based load tests, swipe tests, and constant ratio displacement probe tests are adopted to calculate the uniaxial bearing capacities, failure envelopes in combined V-H, V-M planes, and failure envelopes in a combined V-H-M load space, respectively. A parametric study on the effects of vertical load level V, the layer strength ratio s_u,t/s_u,b, and the hard layer thickness t_1 on the bearing capacities is then performed. Results show that the vertical load level is a key factor that influences the values of H and M and the size of the H-M failure envelope. The existence of the underlying weak clay decreases the bearing capacities in all directions, and the vertical capacity Vult is affected more than the horizontal(H_ult) and moment(M_ult) capacities based on a single uniform deposit. The influence of the underlying weak clay on H-M failure envelope is mainly shown where H and M are coupled in the same direction. In contrast, little difference is observed when H and M are coupled in opposite directions.     

Characteristics and dynamics of the Ganqiuchi rock avalanche triggered by a paleo-earthquake in the Northern Qinling Mountains

Analyzing large prehistoric rock avalanches provides significant data for evaluating the disaster posed by these relatively infrequent but destructive geological events. This paper attempts to study the characteristics and dynamics of the Ganqiuchi granitic rock avalanche, in the middle of the northern margin of Qinling Mountains, 30 km to the south of Xi’an, Shaanxi Province, China. In plane view, this rock avalanche is characterized by source area, accumulation area and dammed lake area. Based on previous studies, historical records and regional geological data, the major trigger of the Ganqiuchi rock avalanche is considered to be a strong paleo-earthquake with tremendous energy. The in situ deposit block size distributions of the intact rock mass and the debris deposits are presented and analyzed by using a simple model for estimating the number of fragmentation cycles that the blocks underwent. The results show that the primary controlling factor of the fragmentation process is the pre-existing fractures, and there is a relationship between the potential energy and the fragmentation energy: the latter is approximately 20% of the former. Based on the dynamic discrete element technique, the study proposes a four-stage model for the dynamic course of the Ganqiuchi rock avalanche:(1) failing;(2) highspeed sliding;(3) collision with obstacles;(4) decelerated sliding, which has implication for hazard assessment of the potential rock avalanches in China and other countries with similar geological setting.     

Oxidation Modification of Polyacrylonitrile-Based Carbon Fiber and Its Electro-Chemical Performance as Marine Electrode for Electric Field Test

A novel sensor for ocean electric field testing has been fabricated by polyacrylonitrile-based on carbon fibers with electro-chemical oxidation.The surface profile characteristics of the carbon fibers were characterized by scanning electron microscope,Fourier transform infrared spectra and contact angle.Cyclic voltammetry and Tafel curves have been used to study its electro-chemical performances.Two identical electrodes in sea water as the electric field sensor will swiftly respond to applied electric field which causes positive and negative ions to move in opposite direction,resulting in a electric potential difference(ΔE).Test result indicates that the offset potential is typically below 1 m V with a drift of 60-170μVd^-1.Typical self noise level is 1.07 nV√Hz^1/2@1 Hz.The electric field response indicates that the modified electrode pair shows better response to AC sine signal of amplitude and frequency(5 mV and 1 mHz)respectively than its blank.The electric field response model of the modified electrodes is creatively presented according to its electric double layer capacitance and Faraday pseudo-capacitance.Many advantages of the carbon fiber electric field electrode will make it have potential application prospect.     

Effect of Carbonation and Drying-Wetting Cycles on Chloride Diffusion Behavior of Coral Aggregate Seawater Concrete

Based on seawater immersion,drying-wetting cycles,carbonation and drying-wetting cycles for coral aggregate sea-water concrete(CASC)with different strength grades,the effect of carbonation and drying-wetting cycles on chloride diffusion be-havior of CASC is studied.The results show that the free surface chloride concentration(Cs),free chloride diffusion coefficient(Df)and time-dependent index(m)of CASC in the drying-wetting cycles is obviously higher than that in seawater immersion.The Df and m of CASC of carbonation and drying-wetting cycles is higher than that in the drying-wetting cycles.Carbonation increases the Df and m of CASC,which is against CASC to resist chloride corrosion.The corrosion possibility of CASC structures in different ex-posed areas is as follows:splash zone(carbonation and drying-wetting cycles)>tidal zone(drying-wetting cycles)>underwater zone(seawater immersion).Besides,the chloride diffusion rate of C65-CASC is 17.8%-63.4%higher than that of C65-ordinary aggre-gate concrete(OAC)in seawater immersion(underwater zone).Therefore,anti-corrosion measures should be adopted to improve the service life of CASC structure in the oceanic environment.     

湘西自治州贯彻执行《土地管理法》调查报告

为推进湘西自治州贯彻执行《中华人民共和国土地管理法》(以下简称《土地管理法》)工作的健康发展,州政协委员视察组一行13人,对《土地管理法》颁布实施以来全州8     

奥利亚罗非鱼微卫星位点的筛选

从GenBank上选取40对尼罗罗非鱼(Oreochromis niloticus)的微卫星引物,分别在奥利亚罗非鱼(Oreo-chromis aureus)(83系)、红色奥利亚罗非鱼、奥利亚罗非鱼(02系)和尼罗罗非鱼的基因组上进行扩增。40对引物中有37对(92.5%)可进行有效扩增,32对引物(80%)可检测到个体间等位基因的多态性。其中引物UNH168与奥利亚罗非鱼的性别相关,在雌性个体中可扩增出二条大小不同的特异带(分别为135和171 bp),在雄性个体中则只有一条(171 bp)。将特异条带回收、克隆并测序,结果显示雌雄个体中171 bp条带的序列完全相同,包括103bp的侧翼序列和34个CA重复,在雌性个体中获得的135 bp条带则只有16个CA重复。引物UNH846、UNH860和UNH995可鉴别奥利亚罗非鱼和尼罗罗非鱼,UNH890可鉴别出红色奥利亚罗非鱼。可见,大部分的尼罗罗非鱼微卫星位点存在于奥利亚罗非鱼中。     

Analysis of new microsatellite markers developed from reported sequences of Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>

The expressed sequence tags (ESTs) of Japanese flounder, Paralichthys olivaceus, were selected from GenBank to identify simple sequence repeats (SSRs) or microsatellites. A bioinformatic analysis of 11111 ESTs identified 751 SSR-containing ESTs, including 440 dinucleotide, 254 trinucleotide, 53 tetranucleotide, 95 pentanucleotide and 40 hexanucleotide microsatellites respectively. The CA/TG and GA/TC repeats were the most abundant microsatellites. AT-rich types were predominant among trinucleotide and tetranucleotide microsatellites. PCR primers were designed to amplify 10 identified microsatellites loci. The PCR results from eight pairs of primers showed polymorphisms in wild populations. In 30 wild individuals, the mean observed and expected heterozygosities of these 8 polymorphic SSRs were 0.71 and 0.83 respectively and the average PIC value was 0.8. These microsatellite markers should prove to be a useful addition to the microsatellite markers that are now available for this species.     

Construction of cDNA subtractive library from pearl oyster (Pinctada fucata Gould) with red color shell by SSH

The molecular basis of color polymorphism in the shells of the pearl oyster Pinctada fucata is largely unknown. We developed a red-shelled family line and used suppression subtractive hybridization (SSH) to screen for differentially expressed genes in red- and non-red-shelled pearl oysters. We constructed forward and reverse cDNA subtractive libraries consisting of 2 506 and 797 clones, respectively. Among 343 randomly selected clones in the forward library, 304 sequences were identified in GenBank using BLASTx and BLASTn. Of the 304 sequences, 13 showed no similarity to known sequences and 291 were matched with known genes of the pearl oyster, including shematrin-1, shematrin-2, shematrin-6, shematrin-7, nacrein, nacrein-like protein, aspein for shell matrix protein, glycine-rich protein, mantle gene 5, 28S, EST00031, EST00036, 16S, and COΙ. In the reverse library, 7 clones were sequenced and analyzed by BLAST. Two sequences shared similarity with EST00036 from the P. fucata subtraction cDNA library, four with the P. fucata mitochondrial gene for 16S rRNA and 1 with P. fucata shematrin-2. We evaluated the expression of 12 genes from the forward library using RT PCR. Two sequences matched with 16S and COΙ so were considered to be false positives. The remaining 10 sequences were differentially expression in the red-shelled pearl oysters. Our results suggest that differential expression of these genes may be related to color variation in the red-shelled family line of the pearl oyster.     

Genome-wide mining,characterization, and development of microsatellite markers in <Emphasis Type="Italic">Marsupenaeus japonicus</Emphasis> by genome survey sequencing

The kuruma prawn, Marsupenaeus japonicus, is one of the most cultivated and consumed species of shrimp. However, very few molecular genetic/genomic resources are publically available for it. Thus, the characterization and distribution of simple sequence repeats (SSRs) remains ambiguous and the use of SSR markers in genomic studies and marker-assisted selection is limited. The goal of this study is to characterize and develop genome-wide SSR markers in M. japonicus by genome survey sequencing for application in comparative genomics and breeding. A total of 326 945 perfect SSRs were identified, among which dinucleotide repeats were the most frequent class (44.08%), followed by mononucleotides (29.67%), trinucleotides (18.96%), tetranucleotides (5.66%), hexanucleotides (1.07%), and pentanucleotides (0.56%). In total, 151 541 SSR loci primers were successfully designed. A subset of 30 SSR primer pairs were synthesized and tested in 42 individuals from a wild population, of which 27 loci (90.0%) were successfully amplified with specific products and 24 (80.0%) were polymorphic. For the amplified polymorphic loci, the alleles ranged from 5 to 17 (with an average of 9.63), and the average PIC value was 0.796. A total of 58 256 SSR-containing sequences had significant Gene Ontology annotation; these are good functional molecular marker candidates for association studies and comparative genomic analysis. The newly identified SSRs significantly contribute to the M. japonicus genomic resources and will facilitate a number of genetic and genomic studies, including high density linkage mapping, genome-wide association analysis, marker-aided selection, comparative genomics analysis, population genetics, and evolution.     

南海海域4种笛鲷的微卫星DNA分析

采用聚丙烯酰胺凝胶电泳技术,从20对西大西洋笛鲷(Lutjanus campechanus)的微卫星引物中筛选适用于红鳍笛鲷(L.erythopterus)、勒氏笛鲷(L.russellii)、紫红笛鲷(L.argentimaculatus)和约氏笛鲷(L.johnii)基因组分析的微卫星引物,分析4种笛鲷的遗传多样性及系统发生。经反应条件的优化,从20对引物中筛选出17对可稳定扩增出特异片段的引物。通过测序证实扩增产物含微卫星位点后,以该17对引物对4个种的群体进行遗传多样性分析。其中16对可在约氏笛鲷、勒氏笛鲷、紫红笛鲷基因组中扩增出重复性好的特异性条带,分别有65%、65%、60%呈现出种内多态;15对可在红鳍笛鲷中扩增出重复性好的特异性条带,并且全部呈现出种内多态。四种笛鲷中,红鳍笛鲷的多态性最高,高度多态基因座占检测座位的66.67%;勒氏笛鲷的多态性最低,低度多态基因座占43.75%。获得3个种间特异性分子标记。用DS和DA两种方法计算4种笛鲷的遗传距离,构建了系统发生树。     

月鳢不同组织中乳酸脱氢酶和酯酶同工酶的比较

采用垂直板聚丙烯酰胺凝胶电泳技术,对月鳢十种组织中乳酸脱氢酶（ＬＤＨ）和酯酶（ＥＳＴ）同工酶进行了比较研究,结果表明：月鳢组织内ＬＤＨ和ＥＳＴ具有明显的组织特异性,ＥＳＴ由２个座位编码,ＬＤＨ则由Ｌｄｈ－ａ、Ｌｄｈ－ｂ两个基因编码。     

Hybrids between olive flounder Paralichthys olivaceus and stone flounder Kareius bicoloratus： karyotype, allozyme and RAPD analyses

The hybrid between olive flounder Paralichthys olivaceus and stone flounder Kareius bicoloratus was produced by artificial insemination of olive flounder eggs with stone flounder sperm. Sinistral and dextral are two types of hybrid progeny after metamorphosis. Karyotypes of both hybrid flounders are the same as those of the two parental species. Of the 22 loci examined from 12 allozymes, 12 confirmed hybridization of the paternal and maternal loci in hybrids and no difference was found in allozyme patterns of sinistral and dextral hybrid fishes. RAPD patterns of these specimens were also studied with 38 primers selected from 104 tested. Among them, the PCR products of 30 primers showed hybridization of the paternal and maternal bands. Genetic variation between hybrids and their parental stocks was analyzed by RAPD using 10 of the above 38 primers. The average heterozygosity and genetic distance were calculated. The results suggested that the filial generation could inherit a little more genetic materials from paternal fish than that from maternal fish. Supported by National Natural Science Foundation of China (No. 30571445), National High-Technology Research and Development Program (863 Program, No. 2006AA10A404), and Project from the Ministry of Science and Technology of China (No. 2006DKA30470-017)     

Identification and characterization of 43 microsatellite markers derived from expressed sequence tags of the sea cucumber (Apostichopus japonicus)

The sea cucumber Apostichopus japonicus is a commercially and ecologically important species in China. A total of 3056 potential unigenes were generated after assembling 7597 A. japonicus expressed sequence tags (ESTs) downloaded from Gen-Bank. Two hundred and fifty microsatellite-containing ESTs (8.18%) and 299 simple sequence repeats (SSRs) were detected. The average density of SSRs was 1 per 7.403 kb of EST after redundancy elimination. Di-nucleotide repeat motifs appeared to be the most abundant type with a percentage of 69.90%. Of the 126 primer pairs designed, 90 amplified the expected products and 43 showed polymorphism in 30 individuals tested. The number of alleles per locus ranged from 2 to 26 with an average of 7.0 alleles, and the observed and expected heterozygosities varied from 0.067 to 1.000 and from 0.066 to 0.959, respectively. These new EST-derived microsatellite markers would provide sufficient polymorphism for population genetic studies and genome mapping of this sea cucumber species.     

军曹鱼群体遗传结构的AFLP分析

筛选出10对扩增片段长度多态分析技术(Amplified fragment length polymorphism,AFLP)的选择性扩增引物(E-aga/M-cgt、E-aga/M-cga、E-agc/M-cga、E-agg/M-cga、E-act/M-cgc、E-aag/M-cgc、E-aca/M-cga、E-aac/M-cgc、E-aac/M-cac和E-aac/M-cat),分析了4个军曹鱼(Rachycentron canadum)全人工繁育群体海南1(HN1)、海南2(HN2)、湛江(ZJ)和流沙湾(LS)的遗传结构。结果表明:总体多态位点比例(83.9%)、分化指数(0.427 8)和Shannon信息指数(0.614 9)均处于较高水平,遗传多样性丰富;主坐标分析和邻位连接树中LS-HN2支与ZJ-HN1支明显分离,各群体内多样性水平存在差异(遗传多样性大小依次为HN1、HN2、LS、ZJ),但总体基因流仍然较大(Nm=10.327),分子方差分析(AMOVA)获得的群内方差(53%)也略大于群间(47%)。