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1.
介绍了事务处理的基本原理,讨论了.NET中的事务处理,说明了ADO.NET和消息队列中的手动事务处理,以及ASP.NET、XML Web service、.NET Framework类中的自动事务处理,并对.NET中的各种事务处理给出了实施的方法,为利用.NET构建具有事务处理的企业应用提供了参考.  相似文献   

2.
Specimens of a new species of Cerithiidae, Cerithium mangrovum n. sp., were collected during two surveys along the coasts of Hainan and Guangdong Province, China. Usually associated with potamidid snails, this species often occurs in large populations between the mid-high tidal zones in a range of habitats, including mangroves, grass beds, silt, mud, and coral reefs. C. mangrovum n. sp. has a slender and tapering shell and the straight-sided whorl bears three aligned beaded spiral cords. The thick outer lip has a wide posterior sinus. It morphologically resembles C. coralium Kiener, 1841. The shell of C. coralium is usually larger and wider and the spiral cords are not as beaded as in C, mangrovum n. sp. Its radula has a rachidian tooth with a shallow, wide, median basal projection while the rachidian tooth of C. mangrovum n. sp. has a moderately long, median basal projection.  相似文献   

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4.
The amphipod crustacean Eogammarus sinensis has useful features that make it suitable for use in the aquaculture of fish and large decapod crustaceans.In this study,we investigated the effects of temperature and salinity on the development,fecundity,survival,and growth rate of E.sinensis.The results show that temperature significantly affected E.sinensis development,but salinity.As temperature increased,the duration of E.sinensis embryonic development decreased.Fecundity was affected significantly by temperature and the combination of temperature and salinity,but by salinity alone.In addition,high temperatures accelerated E.sinensis juvenile growth rates,whereas high salinity reduced it.Therefore,our data suggest that E.sinensis tolerates a wide range of salinities and that temperature has more significant effects than salinity on the embryonic development,fecundity,and growth of E.sinensis.Our results shall be useful for mass production of this species for use in aquaculture.  相似文献   

5.
2008年度的矿山储量动态监测工作,业已结束.通过对矿山的储量动态监测,各地暴露出诸多新问题.给我们的矿政管理带来新困惑.本文就此作一分析、探讨,努力促使我市的矿政管理更加规范、科学和合法. 一、概述 今年参加矿山储量动态监测的矿山共有30多家.根据各县(市、区)反映的情况,主要存在以下几类问题.一是采矿权有效期已届满但累计总量未采完,故矿山企业仍然在生产.二是采矿权有效期未满但企业提前采完核定资源量,矿山仍然在生产.三是采矿权有效期未满,法定储量也未采完,但有越界开采现象.四是采矿权有效期未满,划定资源量也采完,存在越界现象.五是采矿权有效期已届满,划定资源量也采完.且有越界现象.六是矿山企业超年度规模开采矿产资源.  相似文献   

6.
引言 (重耳)出于五鹿,乞食于野人,野人与之块.公子怒,欲鞭之.子犯日:"天赐也."稽首,受而载之. --<左传> 中国人历来敬重土地,爱护土地. 在古老的自然崇拜中,土地崇拜占据着重要位置.几千年前,土地常常作为国家的象征,所以国家也叫社稷,这里的"社"为土地神,"稷"为谷神.土地神和谷神构成了一个农耕国家的主干.在漫长的农业文明中,土地的崇拜情结成为深厚、凝重的中国历史文化的一个底蕴和特征.  相似文献   

7.
Platycephalus in Chinese sea area has a high commercial value.However,there were mis-identifications in previous records.In this study,we fully distinguished and diagnosed all five species,Platycephalus indicus,P.cultellatus,Platycephalus sp.,Platycephalus sp.1 and Platycephalus sp.2.The results revealed that P.cultellatus was overlooked by previous ichthyologists.Platycephalus sp.1 was misidentified as P.indicus in reality,and Platycephalus sp.2 only existed in the seas of Japan.Furthermore,morphological,especially phylogenetic analysis indicated that Platycephalus sp.from South China Sea differs from all former known species,which might be a new species.We identified all Platycephalus species in China seas for the first time,which will contribute to local species identification,biodiversity conservation and sustainable exploitation of Platycephalus species.  相似文献   

8.
The current study explored Aurelia aurita and Rhopilema esculent um consumption by silver pomfret juveniles, as well as their prey selection between the two jellyfi sh species. Silver pomfret juveniles weighing 1±0.1 g actively preyed on both the species. Their daily A. aurita consumption was 11.6 times their own body weights regardless of the size of A. aurita medusae. Their daily R. esculent um consumption was 13, 9.1, 5, and 4.1 times their own body weights when the R. esculentum medusae were 10, 20, 30, and 40 mm in bell diameter, respectively. The survival rates of the R. esculent um were higher than those of the A. aurita. When the R. esculent um medusae were more than 30 mm in bell diameter, their survival rate exceeded 92%. Silver pomfrets serve as a type of potential predators on A. aurita in coastal waters, and they have little infl uence on R. esculent um with a size exceeding 30 mm. Besides, A. aurita may be able to be used as fi sh prey in silver pomfret artifi cial breeding.  相似文献   

9.
Population dynamics of four dominant Antarctic copepods, Calanoides acutus, Calanus propinquus, Metridia gerlachei and Rhincalanus gigas were studied based on zooplankton samples collected in the Prydz Bay during austral summer from 1999 to 2006. We found that C. acutus was the most abundant species among these four copepods, followed by C. propinquus, M. gerlachei and R. gigas. R. gigas occurred mainly in the warmer oceanic regions and showed distribution patterns discrete from the other three species, whose distribution in the whole survey area overlapped. By December 15th (about one month before our sampling) of the years 1999, 2003 and 2006, sea ice retreated earlier and polynyas existed in the neritic region one month before sampling. These periods were characterized by numerical dominance of C. acutus, C. propinquus and M. gerlachei, elevated proportions of Copepodite I and Copepodite II stages especially in the neritic region. While for the years 2000, 2002, and 2005, the ice edge located more northerly and polynyas did not exist in the neritic region, the copepods abundance was lower, indicating poor recruitment. Population structure of R. gigas was mainly composed of advanced stages Copepodite V and female during all cruises. Log10 (x+1) transformed densities of C. acutus, C. propinquus and M. gerlachei showed positive correlation with temperature and chlorophyll a concentration, while mean population stages of these copopods were negatively correlated with these environmental variables. Younger copepodite stages of C. acutus, C. propinquus and M. gerlachei appeared more often in neritic regions. We confirmed that the polynyas had a great contribution to phytoplankton blooms, which promote copepods reproduction and recruitment success. The study suggested that population dynamics of the four copepods have good correspondence with sea ice and polynya variations during all cruises of the Prydz Bay.  相似文献   

10.
To clarify the confusion surrounding species identification and state intraspecific variations, this research studied the morphological taxonomy of five species, Kentrophyllum cf. setigerum Petz et al., 1995; Zosterodasys shumerica Aliev, 1990; Frontonia tchibisovae Burkovsky, 1970; Neourostylopsis orientalis Chen et al., 2013; and Apoholosticha cf. sinica Fan et al., 2014, which were collected from Chongming Island's marsh wetlands. Kentrophyllum cf. setigerum possesses less somatic kineties than K. setigerum(19–26 right and 18–25 left kineties vs 35–40 right and 30 left kineties). Whether Z. shumerica is identical to Z. transversa Foissner et al., 1994, which was presented in a previous report, was negated. The improved diagnosis for the species is provided. Frontonia tchibisovae was confirmed to have three or four micronuclei, and the number of kinetosome rows in its peniculus 3 varied between China and Russia populations. The new population of N. orientalis bears cortical granules, which differs from the original population that has an arrangement of rows across the dorsal bristles. For A. cf. sinica, there are colorless cortical granules on the ventral side of the new population, whereas in the previously reported populations bright orange, spherical granules were clustered around dorsal cilia. Additionally, we sequenced the small-subunit(SSU) rRNA genes of K. cf. setigerum, N. orientalis, and A. cf. Sinica, and compared the new and reported populations. For the first time, we also provide a species list, including 33 ciliates collected from the wetlands based on living observation and silver staining.  相似文献   

11.
From June 2003 to June 2004, an investigation on the life cycle, production and trophic basis of dominant species of macrozoobenthos community in a second-order river of the Hanjiang River basin, Hubei, China was carded out. The results showed that the dominant species Leptophlebia sp. and Ephemera sp. appeared to develop two generations per year, and there was a small overlap in the two generations of both species. The pupation of Leptophlebia sp. mainly occurred in autumn and winter, while pupation of Ephemera sp. mainly took place in summer and winter. The standing stocks of the Leptophlebia sp. population and Ephemera sp. population had two peaks in a year. The cohort production and cohort P/B ratio of the Leptophlebia sp. population estimated by size frequency method were 19.018 1 g/m^2.a and 5.7 respectively, while its annual production and P/B ratio were 38.036 2 g/m^2.a and 11.4. The cohort production and cohort P/B ratio of the Ephemera sp. population were 38.015 9 g/m^2.a and 5.9, while its annual production and P/B ratio were 76.031 8 g/m^2.a and 11.8.  相似文献   

12.
Karenia mikimotoi (Miyake & Kominami ex Oda) Hansen & Moestrup is associated with harmful algal blooms in temperate and subtropical zones of the world. The hemolytic substances produced by K. mikimotoi are thought to cause mortality in fishes and invertebrates. We evaluated the composition of the hemolytic toxin produced by K. mikimotoi cultured in the laboratory using thin-layer chromatography.In addition, we evaluated the effect of co-occuring algae (Prorocentrum donghaiense and Alexandrium tamarense) and the cladoceran grazer Moina mongolica on hemolytic toxin production in K. mikimotoi. The hemolytic toxins from K. mikimotoi were a mixture of 2 liposaccharides and 1 lipid. Waterborne clues from P. donghaiense and A. tamarense inhibited the growth of K. mikimotoi but increased the production of hemolytic toxins. Conversely, K. mikimotoi strongly inhibited the growth of caged P. donghaiense and A. tamarense. In addition, the ingestion of K. mikimotoi by M. mongolica induced the production of hemolytic toxins in K. mikimotoi. Taken together, our results suggest that the presence of other microalgae and grazers may be as important as environmental factors for controlling the production of hemolytic substances. K. mikimotoi secreted allelochemicals other than unstable fatty acids with hemolytic activity. The production of hemolytic toxins in dinoflagellates was not only dependent on resource availability, but also on the risk of predation. Hemolytic toxins likely play an important role as chemical deterrents secreted by K. mikimotoi.  相似文献   

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14.
没有哪个节日需要这么长久的等待,一等就是7年,一等就是13年. --这就是广西融水县、三江县苗族的手拉鼓节.拉鼓节的主题就是祭祀.祭祀的仪式就是打鼓、拉鼓.鼓分大小,大鼓长约一丈三,小鼓长约七尺;拉大鼓节每13年举行一次,拉小鼓节每7年举行一次.一个节日在时间上间距这么长,少有.但也正因为如此,这个节日就显得特别隆重.  相似文献   

15.
近年作者(1988—1990)在辽阳兰家寒武纪崮山组发现了笔石生物群,新建Dendrograptusliaoyiangensis sp.nov..D.liaoyiangensis latus subsp.nov.,Callograptus lanjiaensis sp.nov.。其特征为笔石个体小,枝短粗,具附着盘,胞管简单,固着底栖,分布局限,具有地方色彩,是目前已发现的最古老的笔石生物群。根据前人研究结果(穆恩之、林尧坤)和作者的研究认为,寒武系风山组Dictyonema wu-tingshanense是原始漂浮笔石,在太子河流域出现层位最低;凤山组燕州段笔石属底栖和漂浮的混合生态笔石群。同时作者在辽东半岛南部寒武系凤山组湾湾沟段和下楸树沟段发现笔石生物群,新建Dictyonema jin-zhouense sp.nov.Callograptus viminalis sp.nov.C.lashushanensis sp.nov.。作者的研究表明,太子河流域寒武系崮山组的笔石是最古老的笔石,因而太子河流域很可能是太平洋型和大西洋型笔石动物群的发源地。  相似文献   

16.
通天之路     
生老病死,是自然规律.而对于死,彝族人显得更自然更从容一些.彝族分布甚广,各个分支的丧葬风俗各有异同,真可谓是同一种生百种死.然而,万变不离其宗,相同的文化基因,使不同地方的彝族在丧葬方面,基本保持了大同小异的习俗. 彝族的丧葬风俗始自远古.在古代,人们普遍实行的是火葬.一堆柴,一把火,骨灰留了下来,灵魂上了天堂.明清以后,土葬渐渐替代火葬,从此,丧葬习俗才变得丰富而繁杂.  相似文献   

17.
《国土资源》2016,(4):4-9
1968年初,我结束了在北京地质学院8年的学习生活.春节回天津向父母告别后,返回北京.在一个寒冷的夜晚,我挤上了从北京驶往兰州的列车. 列车在朔风怒号中开动了.我此行是前往甘肃省地质局报到.那将是我从事地质工作的新起点.  相似文献   

18.
Phytoplankton blooms occurring in the Jiangdong Reservoir of Jiulong River, Fujian Province, South China, are a potential source of contamination of the drinking water of Xiamen (Amoy) City. To understand the main factors governing phytoplankton composition and succession, we sampled phytoplankton and measured environmental parameters in the reservoir, weekly or biweekly from Jan. 2010 to Feb. 2012. We identified 123 species of phytoplankton from 7 phyla and 74 genera. The major phyla were Chlorophyta, Bacillariophyta, Cryptophyta, Cyanophyta, and Dinophyta. The main trend in the succession of phytoplankton was from prevalence of Cryptophyta-Bacillariophyta communities to those of Chlorophyta-Cyanophyta. High cell concentrations of Cryptophyta, predominantly Komma caudate, Cryptomonas marssonii, and Cryptomonas erosa, were present in winter, associated with low river discharge and cold water. Bacillariophyta, primarily Cyclotella meneghiniana, Aulacoseira granulata, and Aulacoseira granulata var. angustissima, dominated in early spring, coinciding with high turbulence and low irradiance. During early summer and autumn, Chlorophyta, comprising Scenedesmus quadricauda, Dictyosphaerium ehrenbergianum, and Pandorina sp. were prevalent during conditions of warmer water temperatures and low turbulence. Cyanophyta, with dominance ofPseudanabaena mucicola, Merismopedia tenuissima and Raphidiopsis sp. increased throughout the summer, coinciding with higher water temperatures and lower nutrient concentrations. Dinophyta content was occasionally high during winter and summer. Peridiniopsis penardii (Dinophyta) bloomed during winter 2009, with a persistently high biomass recorded into early spring. Canonical correspondence analysis indicated that phytoplankton communities were influenced by river discharge, irradiance, water temperature, and nutrient concentrations.  相似文献   

19.
Algal allelopathy is an ecological/physiological phenomenon that has focused attention on the interactions among algae and the production of algal toxins. We investigated the allelopathic interactions between the dinoflagellate genus Prorocentrum micans and diatom genus Skeletonema costatum and between P. micans and dinoflagellate genus Karenia mikimotoi using bi-algal cultures. Because the effects were species-specific and size-dependent, we evaluated the effect of different initial densities. At low densities of P. micans and high densities of S. costatum inoculated into the same medium, the growth of P. micans was weakly restrained, whereas the growth of S. costatum was significantly suppressed. S. costatum and K. mikimotoi were strongly inhibited by P. micans, in both the bi-algal cultures and enriched filtrates. Direct cell-to-cell contact was not necessary to gain a competitive advantage, thus, our results suggest that P. micans inhibited the growth of S. costatum and K. mikimotoi by the release of allelochemical(s). Last, a mathematical model was used to simulate growth and interactions between P. micans and S. costatum and between P. micans and K. mikimotoi in bi-algal cultures.  相似文献   

20.
空间数据挖掘是解决海量空间数据利用瓶颈的技术之一.本文综述空间数据挖掘的研究与应用进展.首先,分析空间数据挖掘的缘起.其次,研究空间数据挖掘的本质及其特点.再次,基于理论技术,分类总结空间数据挖掘的研究和应用的成果,并探讨其研究方向.最后,总结全文.  相似文献   

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