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1.
《地理信息世界》2005,3(3):25-25
电子政务是指政府机构运用现代计算机和网络技术,将其管理和服务职能转移到网络上去完成,同时实现政府组织结构和工作流程的重组优化,超越时间、空间和部门分隔的制约,向全社会提供高效优质、规范透明和全方位的管理与服务。其意义在于突破了传统的工业时代“一站式”政府办公模式,建立了适应网络时代的“一网式”、“一表式”新模式,开辟了推动社会信息化的新途径,创造了政府实施产业政策的新手段,实现管理服务水平的跨越式发展。  相似文献   

2.
This paper reports for the first time a species of polychaetous family Paraonidae, Paraonella platybranchia (Hartman, 1961), a rare species found previously only in the coast near the boundary between the United States and Mexico, and it was recently discovered in the samples collected in 1982 from Chinese side of the Yellow Sea. This is the first record of the species in China as well as in the Northwest Pacific.  相似文献   

3.
2.大禹疏壶口 壶口瀑布,是黄河干流中最壮观的瀑布,它以平均1000个流量(立方米/秒)的速度,从30多米的高处在这宽仅20多米的峡口中倾泻而下,激起50米高的水花,飞出彩虹,浪沫漂到下游100-200米岸上,给游人身上增添点点泥沫。  相似文献   

4.
5.
《国土资源》2011,(10):42-42
什么是高标准基本农田?高标准基本农田须达到哪些标准?建设过程中公众如何参与?日前,国土资源部印发《高标准基本农田建设规范(试行)》,明确了高标准基本农田建设的目标、任务、原则、建设内容与技术要求、建设程序等,首次从国家层面规范高标准基本农田建设工作。  相似文献   

6.
设k∈N,f(z)为复平面上的超越亚纯函数,φ(z)、ak-1(z),…,a0(z)为f(z)的小函数,且φ(z)≠0.置P(f)(z)=f^(k)(z)+ak-1(z),f^(k-1)(z)+…+a1(z)f(z)+a0,(z),且P(f)(z)不恒为常数.当k≤4时,满足Nr)(r,1/f)=S(r,f);k≥5,满足N4)(r,1/f)=S(r,f),则T(r,f)〈20N^-(r,1/φfP-1)+s(r,f).  相似文献   

7.
这里有唐代谓之湄沱湖,金代称之北琴海的兴凯湖。它烟波浩淼,横无涯际,水天一色,景致绮丽。这里的春夏秋冬因兴凯湖相伴而超凡脱俗、与众不同;这里的湖光景致更因四季变换而美妙绝伦。春到兴凯,一夜东风,红粉杏花,竞相开放,云霞蒸蔚,香飘湖畔。盛夏兴凯,万顷浪涛,青波荡漾,百里湖滩,金沙灿灿,花影绿幛,鸟鸣莺啼。兴凯之秋,碧空如洗,湖光内敛,山色凝重,岸上层叠,浸染枫红。冬临兴凯,寒风劲吹,漫天飞雪,瞬间浪涛平息,湖面冰封如镜,楼台白雪霜树,玉宇琼阁仙境。松阿察河,凝霜挂雪,披银垂玉,似花非花,满目雾凇。  相似文献   

8.
Ureilites share the characteristics of differentiated meteorites and of primary chondrites. GRV 024237 is a ureilite, which was found in the 19th Chinese National Antarctic Research Expedition (CHINARE), at the No. 4 moraine, Grove Moun- tains, Antarctica. GRV 024237 consists mainly of coarse-grained olivine (60 vol%), pigeonite (30 vol%) and opaque minerals (10 vol% ). Tri-junction texture between olivine and pigeonite is common. Carbonaceous materials with minor amounts of troilite and nickel-iron metal were observed as interstitial phases. The Fa value of olivine composition varies from 6.2 to 16.8 from rim to core, but pyroxene is homogeneous in composition, with Fs 14.0 to 15.5. Both olivine and pyroxene have normal extinctions. Net-like iron or limonite veins filled in the fractures of olivine and pyroxene, and no diamond was observed. Based on petrographic and mineralogical features, GRV 024237 is a Type I and Group 2 monomict ureilite.  相似文献   

9.
April, 1996 to March, 1997 studies on the abundance and secondary production of Limnodrilus hoffmeisteri in an algae-dominated lake showed that the worm density and biomass peaked in December at 152 ind/m^2 and 0.087 g/m^2 , respectively. The secondary production of the animal was 0.294g/m^2 fresh wt/a. The turnover rate (P/B ratio) was 11.4.  相似文献   

10.
科学攻进“冬宫” “危机矿山接替资源找矿”,是风险与机遇并存、困难与希望同在的战略工程,必须对历史负责,对后人负责,不能留下遗憾,更不能留下败笔。  相似文献   

11.
The association of scyphomedusae with invertebrates has been long known in the literature; especially with hyperiids amphipods. The association of echinoderms with jellyfish is not common and rarely recorded. We reported the association of the ophiuroid Ophiocnemis marmorata with the rhizostome scyphomedusa Rhopilema hispidum collected in Vellar estuary (on the southeast coast of India). O. marmorata is supposed to be a filter feeding ophiuroid, quite common in soft bottom of shallow waters. The brittle stars possibly seek for food supply, shelter and protection through the association.  相似文献   

12.
研究了云斑尖塘鳢(Oxyeleotris marmorata)幼鱼的摄食特性。结果表明:在幼鱼阶段,云斑尖塘鳢的摄食方式为主动掠食;个体全长10mm的日摄食量约为体重的11.66%,40mm的日摄食量约为体重的51.04%,69mm的日摄食量约为体重的55.30%;日摄食量与幼鱼全长呈正相关关系:A=11.3577+0.7664L(r=0.876);云斑尖塘鳢幼鱼的适口饵料鱼全长为其全长的25%~50%,幼鱼摄食15~17h后可完全消化饵料鱼;云斑尖塘鳢幼鱼昼夜摄食节律明显,一昼夜出现一个摄食高峰,高峰时段为19:00-01:00。  相似文献   

13.
Linkage disequilibrium(LD) can be applied for mapping the actual genes responsible for variation of economically important traits through association mapping.The feasibility and efficacy of association studies are strongly dependent on the extent of LD which determines the number and density of markers in the studied population,as well as the experimental design for an association analysis.In this study,we first characterized the extent of LD in a wild population and a cultured mass-selected line of Pacific oyster(Crassostrea gigas).A total of 88 wild and 96 cultured individuals were selected to assess the level of genome-wide LD with 53 microsatellites,respectively.For syntenic marker pairs,no significant association was observed in the wild population;however,three significant associations occurred in the cultured population,and the significant LD extended up to 12.7 c M,indicating that strong artificial selection is a key force for substantial increase of genome-wide LD in cultured population.The difference of LD between wild and cultured populations showed that association studies in Pacific oyster can be achieved with reasonable marker densities at a relatively low cost by choosing an association mapping population.Furthermore,the frequent occurrence of LD between non-syntenic loci and rare alleles encourages the joint application of linkage analysis and LD mapping when mapping genes in oyster.The information on the linkage disequilibrium in the cultured population is useful for future association mapping in oyster.  相似文献   

14.
In the warm summer of 2017,a landslide failed from the south-east side of the Col des Clochettes on the top of the underlying Trajo Glacier.The study area is at an elevation of about 3500 m a.s.l.in the Gran Paradiso Massif and can be hardly reached by walking from Cogne(Aosta Valley,NW Italy).Studies conducted by field surveys,photogrammetry(structure from motion)and satellite images analysis,integrated with the evaluation of data from meteorological stations have been used to reconstruct the phenomenon and infer its causes.The site is very complex to be studied especially due to logistic problems,therefore,measurements and observations that are common practice in other landslides are very difficult to apply here.So,many of the results achieved are not adequately supported by field studies.Anyway,the following factors could have affected the stability of the slope:i)the tectonic structure of the area,which is reflected on the morphology and on the geomechanics characteristics of the rock masses;ii)the meteorological conditions during 3 months before the main failure,resulting in an extremely high temperature compared to historical data.Moreover,the analysis of multitemporal satellite images allowed to recognize that it was not a single landslide but that the phenomenon is articulated over time in at least five failures in about 2 months.Moreover,several predisposing factors may have been playing an important role in causing the instability:the degradation of permafrost(probably affecting rock mass due to the circulation of warm air and water in the discontinuity systems),the alternance of the freeze-thaw cycles and the availability of a considerable amount of water from rainfalls and nival fusion infiltrating deeply in the rock mass.More common causes such as rains and earthquakes have been excluded.  相似文献   

15.
Yu  Nan  Sun  Song  Zhang  Guangtao  Zhang  Fang 《中国海洋湖沼学报》2021,39(1):173-184
Ophiopholis mirabilis is a common species with a high population density on the western coasts of the northern Pacific Ocean.The number of O.mirabilis has been increasing recently in the scallop aquaculture zone(the Zhangzi Island area,northern Yellow Sea) in China.To explore the mechanism of its population variation,the reproductive cycle of O.mirabilis was investigated in this area(39°04'N;122°51'E) from February 2017 through January 2018 and determined by the monthly gonad index(GI),histological examinations of the gonads and the oocyte size-frequency distribution.O.mirabilis had a clear annual reproductive cycle that was synchronous between males and females.Sea temperature and food availability played important roles in O.mirabilis reproduction.The GI value was less reliable for determining reproductive activity in O.mirabilis because the nutritive tissues within the gonads may be utilized to synthesize gametes,leading to a decrease in GI during maturation.The histological results also show that abundant nutritive phagocytes were present in the gonads of O.mirabilis,which,together with the germ cells,affected the weight of the gonads.In addition,the mature oocytes of O.mirabilis were relatively small(75-150 μm),indicating that the larval development was planktotrophic.This study provided insights into the reproductive patterns and biology of O.mirabilis and is an essential basis for the quantity control of this species in aquaculture areas.  相似文献   

16.
Linkage disequilibrium (LD) can be applied for mapping the actual genes responsible for variation of economically important traits through association mapping. The feasibility and efficacy of association studies are strongly dependent on the extent of LD which determines the number and density of markers in the studied population, as well as the experimental design for an association analysis. In this study, we first characterized the extent of LD in a wild population and a cultured mass-selected line of Pacific oyster (Crassostrea gigas). A total of 88 wild and 96 cultured individuals were selected to assess the level of genome-wide LD with 53 microsatellites, respectively. For syntenic marker pairs, no significant association was observed in the wild population; however, three significant associations occurred in the cultured population, and the significant LD extended up to 12.7 cM, indicating that strong artificial selection is a key force for substantial increase of genome-wide LD in cultured population. The difference of LD between wild and cultured populations showed that association studies in Pacific oyster can be achieved with reasonable marker densities at a relatively low cost by choosing an association mapping population. Furthermore, the frequent occurrence of LD between non-syntenic loci and rare alleles encourages the joint application of linkage analysis and LD mapping when mapping genes in oyster. The information on the linkage disequilibrium in the cultured population is useful for future association mapping in oyster.  相似文献   

17.
Clibanarius,a genus of hermit crabs,is one of the most diverse genera within Diogenidae.However,studies on the phylogeny within Clibcanarius is very limited.We reconstruct the molecular phylogeny of the genus Clibanarius based on two mitochondrial(16 S rRNA and COI)and two nuclear protein-coding(NaK and PEPCK)genes using a multigene phylogenetic approach.Eleven selected Clibanarius species from the Indo-West Pacific are analyzed and the Bayesian and maximum likelihood analyses produced identical results in topology.Results suggest that C.rutilus and C.infraspinatus are more closely related to each other than to C.snelliusi,and C.striolatus shows a close relationship to C.longitarsus.The close association of C.merguiensis with C.englaucus and C.humilis is strongly supported by the divergence of C.virescens from them.Our phylogenetic results contradict the morphological classification scheme proposed for Clibanarius and indicate that the relative length of dactyls and propodi is not phylogenetically significant in Clibanarius.In addition,we speculate that the morphological characteristic of the median cleft of the telson might be phylogenetically important for Clibanarius.  相似文献   

18.
Luidia Forbes (Paxillosida: Luidiidae) are common soft bottom sea stars with 49 described species. Because of substantial morphological diversity, the taxonomy of the genus is complex and hasn’t been resolved definitely. In order to resolve general taxonomic issues, and determine species boundaries and phylogenetic relationships within the genus Luidia, the sequences of cytochrome oxidase subunit I (COI) gene from 24 specimens of Luidia, belonging to eight taxa in Chinese waters, were studied. Three sequences of two species in genus Luidia from GenBank were used to analyze the phylogenetic relationships. The molecular phylogeny exhibited three main clades, each with strong bootstrap support: Clade A including Luidia quinaria from the Sea of Japan; Clade B including seven nominal species (L. quinaria von Martens, L. yesoensis Goto, L. changi Liu, Liao and Li, L. orientalis Fisher, L. avicularia Fisher, L. longispina Sladen and L. hardwicki Gray) from Chinese waters; and Clade C including L. maculata Müller & Troschel from Chinese waters. Our molecular phylogeny results support the morphological Quinaria-Group and Alternata-Group assigned by Döderlein. Seven nominal species we sampled do not exhibit genetic distances that are large enough to recognize them as separate species. Cryptic species may exist in’ Luidia quinaria’ from the Yellow Sea and the Sea of Japan. Meaningful morphological characters need further investigation in Luidia.  相似文献   

19.
Cytochrome P450 (CYP) superfamily is one of the membership largest and function most diverse protein superfamily recogniozed among living beings. Members of this superfamily were further assigned to different families and subfamilies based on their amino acid similarities. According to their phylogenetic relationships, the CYP genes which likely diverged from common ancestor gene and may share common functions were grouped into one clan. Widely distributing scallops are a group of the most conspicuous bivalve; however the studies on their CYP is acarce. In this study, we searched the genome and expressed sequence tags of Zhikong scallop (Chlamys farreri) for CYP genes. In total, 88 non-redundant CYP were identified, which were homed in 13 CYPs gene families. Phylogenetic analysis divided these genes into 4 CYP clans. As in deuterostomes, Clan 2 was the largest, which contained 33 genes belonging to CYP1, CYP2, CYP17 and CYP356 families. Clan 3 contgained 19 genes belonging to CYP3, CYP5 and CYP30 families. Clan 4 contained 23 genes, all belonging to CYP4 family. The mitochondrial CYP clan contained 9 genes belonging to CYP10 and CYP24 families. In comparison, protostomes (C. farreri, D. pluex, D. melanogaster) contained more CYP genes than deuterostomes (S. purpuratus and vertebrates) in Clan 2 but less genes in Clan 3 and Clan 4. Our findings will aid to deciphering CYP function and evolution in scallops and bivalves.  相似文献   

20.
6个不同鲤群体的形态差异分析   总被引:4,自引:0,他引:4  
对黄河鲤、荷包红鲤、高背荷包红鲤、兴国红鲤、建鲤和黑龙江野鲤等6个鲤群体的12个形态比例性状进行单因素方差分析、主成分分析和聚类分析。单因素方差分析结果表明,除眼后头长/头长外,各鲤群体间在其他比例性状上出现较明显的差异。主成分分析构建了3个主成分,其贡献率分别为35.316%、23.221%、10.146%,累计贡献率为68.683%,并明显可将6个鲤群体划分为2个簇,荷包红鲤和高背荷包红鲤明显与其他群体区分开。聚类分析结果与主成分分析一致。在体高/体长、头长/体长、体厚/体长和尾柄高/尾柄长等4个比例性状上,有些群体的差异系数大于1.28,说明这些群体在这4个指标上的差异可达到亚种水平。结果表明,6个鲤群体在形态上存在一定差异和分化,主要体现在体型和头部特征上。  相似文献   

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