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991.
以西双版纳勐景来景区为案例地,通过访谈、观察等方法,在构建村寨型景区开发企业与社区之间资源相互依赖关系分析框架的基础上,探讨村寨型景区开发企业与社区关系动态演变背后的逻辑。研究发现,村寨型景区开发企业与社区关系的动态演变是二者资源相互依赖程度变化作用的结果。在景区发展初期,开发企业对社区的依赖程度小于社区对开发企业的依赖程度,即在两者的利益博弈中,开发企业的权力比社区大,社区得到的利益从零开始不断增大,二者矛盾较少。在景区发展成熟期,开发企业对社区的依赖程度大于社区对开发企业的依赖程度,即在两者的利益博弈中,社区的权力比开发企业大,此时在已有的利益分配机制不变的情况下,会因利益分配导致社区与开发企业冲突。此外,还推论出在政府干预和协调下,村寨型景区开发企业在与社区的利益冲突中会让步于社区这一结论,可为企业投资村寨型景区开发提供现实指导。  相似文献   
992.
恢复人工植被是祁连山自然保护区矿区废弃地修复的主要手段,经过近5年的修复,矿区废弃地修复区地上植被盖度明显提高,但关于作为评价土壤修复效果重要指标的土壤动物群落变化的认识还很有限。以祁连山自然保护区典型煤矿废弃地为研究对象,采用野外调查的方法对比研究了煤矿修复区和毗邻区(原始地貌)大型土壤动物分布特征及其影响因素。结果表明:(1)修复区植物丰富度、生物量、盖度及土壤粗砂、有机质、全氮含量均显著低于毗邻区(P<0.05),而土壤水分、细砂、黏粉粒、全钾和全磷含量差异不显著(P>0.05)。(2)修复区土壤动物活动密度和多样性均显著高于毗邻区,修复区和毗邻区土壤动物均以蝗科(12.7%和55.7%)和蚁科(14.4%和49.6%)为主;进房沟、水磨沟和柳树沟煤矿修复区及毗邻区土壤动物群落相似性分别为39.9%、52.9%和43.4%。(3)土壤有机质含量是影响煤矿修复区和对照区捕食性土壤动物群落变化的主要因子,而草本物种数和土壤粗砂含量是影响植食性土壤动物群落变化的主要因子。总之,人工修复后煤矿废弃地修复区土壤动物个体数均高于对照区,部分矿区修复生境类群丰富度及多样性已经超过了毗邻区,这表明蚂蚁、步甲和蝗虫等地表节肢动物对煤矿矿区覆土恢复植被和封禁等措施驱动的植被和土壤环境变化响应敏感。因此,还需要优化植被及土壤修复模式,提高土壤动物多样性及多功能性,使矿区废弃地生态环境能够得到快速修复。  相似文献   
993.
正The order Diptera(Insecta)is one of animal groups most successful in the colonization of mineralized shallow aquatic and semiaquatic environments.At the same time,the taxonomic composition of Diptera,their role in  相似文献   
994.
正1 Introduction Regosol in Eastern Siberia is intrazonal soil.In Priolkhonie region it occurs among chestnut soils,salt marshes and solonetzes.There are small information about Tagotskij hydrolaccolith in the research articles of geologists,archaeologists,and paleolimnologists when  相似文献   
995.
Marine gas hydrate and cold-seep systems, which maintain a large amount of methane in the seabed, may critically impact the geochemical and ecological characteristics of the deep-sea sedimentary environment. However, it remains unclear whether marine sediments associated with gas hydrate harbor novel microbial communities that are distinct from those from typical marine sediments. In this study, microbial community structures thriving in sediments associated with and without gas hydrate in the eastern Japan Sea were characterized by 16S rRNA gene-based phylogenetic analyses. Uncultivated bacterial lineages of candidate division JS1 and a novel group NT-B2 were dominant in the sediments from gas hydrate-associated sites. Whereas, microbial populations from sites not associated with gas hydrate were mainly composed of Bacteroidetes, Nitrospirales, Chlamydiales, Chlorobiales, and yet-uncultured bacterial lineages of OD1 and TM06. The good correlation between the dominance of JS1 and NT-B2 and the association of gas hydrate could be attributed to the supply of more energetically favorable energy sources in gas-rich fluids from the deep subsurface than refractory organic matter of terrigenous and diatomaceous origin.  相似文献   
996.
Cyanobacterial mats are found at various locations along the coast of the Eastern Province of Saudi Arabia. Those mats were affected by severe oil pollution following 1991 oil spill. In this study, samples from Abu Ali Island were collected at three selected sampling sites across the intertidal zone (Lower, Middle, and Upper) in order to understand the effect of extreme environmental conditions of high salinity, temperature and desiccation on distribution of cyanobacteria along the oil polluted intertidal zone. Our investigation of composition of cyanobacteria and diatoms was carried out using light microscopy, and Denaturant Gradient Gel Electrophoresis (DGGE) technique. Light microscopy identification revealed dominant cyanobacteria to be affiliated with genera Phormidium, Microcoleus, and Schizothrix, and to a lesser extent with Oscillatoria, Halothece, and various diatom species. The analysis of DGGE of PCR-amplified 16S rRNA fragments showed that the diversity of cyanobacteria decreases as we proceed from the lower to the upper intertidal zone. Accordingly, the tidal regime, salinity, elevated ambient air temperature, and desiccation periods have a great influence on the distribution of cyanobacterial community in the oil polluted intertidal zone of Abu Ali Island.  相似文献   
997.
基于2016—2019年夏季在长江口海域进行的4个航次的生态环境调查,分析了长江口海域季节性低氧对大型底栖动物群落结构的影响。结果表明,2016—2019年长江口海域夏季底层DO最低值为1.51 mg/L,存在不同程度的底层低氧现象。低氧区与非低氧区之间大型底栖动物的种类数量、丰度、生物量和群落结构均存在显著差异。多毛类表现出对低氧较强的耐受能力,为低氧区的主要优势类群,中蚓虫(Mediomastus sp.)、索沙蚕(Lumbrinereis sp.)为低氧区的主要优势种。软体动物、甲壳动物和棘皮动物的分布趋势则与多毛类相反,其中甲壳动物对低氧的耐受能力较弱。MDS多维尺度排序表明,低氧区与非低氧区之间大型底栖动物的群落组成差异明显;CCA分析表明,长江口海域夏季底层低氧已对大型底栖动物的群落结构产生一定程度的影响。  相似文献   
998.
根据2018年春、秋两季在石狮东部近岸海域进行调查所获得的数据,研究了该海域浮游植物的群落结构,并对浮游植物群落与环境因子的关系进行了相关性分析。通过春、秋两季的调查,经初步鉴定,共145种浮游植物,隶属于3门51属,种类以硅藻为主,其中硅藻122种,甲藻21种,蓝藻2种。在春季的调查中,优势种有奇异棍形藻(Bacillaria paradoxa)、密连角毛藻(Chaetoceros densus)等7种,秋季的优势种有中肋骨条藻(Skeletonema costatum)、琼氏圆筛藻(Coscinodiscus jonesianus)等5种。浮游植物细胞密度在1.81×10~4~410.65×10~4cells/m~3之间,春季明显高于秋季。春季多样性指数(H')平均值为3.24,秋季为3.31。相关性分析结果表明,影响石狮东部近岸海域浮游植物群落的主要环境因子有水温、盐度、无机氮含量和活性磷酸盐含量。  相似文献   
999.
Immigration and community development in New York City   总被引:1,自引:0,他引:1  
Community development corporations play a central role in the provision of affordable housing and social services in the contemporary American welfare state. This organizational form, however, emerged in the distinctive, historical political-economic context of the Black Power Movement and America's Great Society. American cities are now very different places, transformed by immigration from spaces of Black–White separation to much more heterogeneous and diverse spaces. In this article, our central question is whether, and how, these vital service organizations are incorporating immigrants into their work. We find that the answer varies, and such variations indicate differential access, or “differential citizenship”—in the urban structure of the contemporary American welfare state.  相似文献   
1000.
Distribution patterns and trophic contributions of rotifers from freshwater through polyhaline estuarine waters were examined in the southern Chesapeake Bay and its major tributaries for a two-year period. Trichocerca marina and Synchaeta spp. were the major taxa in abundance, followed by Polyarthra vulgaris, Keratella cochlearis and Brachionus spp. There was a significant negative correlation between salinity and rotifer density, biomass, and number of species. Rotifers were a component of the microzooplankton biomass during specific periods and at particular sites, dominating summer assemblages in tidal freshwater and river–estuary transition sites, plus the winter communities in estuarine waters. This observation indicates that rotifers may play an important trophic role by seasonally replacing metazoan nauplii as a biomass source in both tidal freshwater and estuarine ecosystems. The annual contribution of rotifers to the total microzooplankton biomass exclusive of heterotrophic dinoflagellates was brief but intensive, achieving over 50% of annual biomass during a 2–3 month period. Despite the small annual mean contribution of rotifers to the total microzooplankton biomass, rotifers may have a limited, but significant impact on the trophic dynamics of the zooplankton community in Chesapeake Bay and its major tidal tributaries.  相似文献   
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