首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   10977篇
  免费   73篇
  国内免费   47篇
安全科学   255篇
废物处理   628篇
环保管理   856篇
综合类   1481篇
基础理论   2537篇
环境理论   9篇
污染及防治   3288篇
评价与监测   915篇
社会与环境   1083篇
灾害及防治   45篇
  2023年   103篇
  2022年   218篇
  2021年   238篇
  2020年   110篇
  2019年   136篇
  2018年   271篇
  2017年   277篇
  2016年   388篇
  2015年   242篇
  2014年   438篇
  2013年   937篇
  2012年   513篇
  2011年   645篇
  2010年   482篇
  2009年   451篇
  2008年   564篇
  2007年   588篇
  2006年   489篇
  2005年   420篇
  2004年   353篇
  2003年   346篇
  2002年   301篇
  2001年   346篇
  2000年   222篇
  1999年   144篇
  1998年   69篇
  1997年   83篇
  1996年   68篇
  1995年   94篇
  1994年   88篇
  1993年   73篇
  1992年   74篇
  1991年   75篇
  1990年   78篇
  1989年   60篇
  1988年   66篇
  1987年   59篇
  1986年   56篇
  1985年   47篇
  1984年   48篇
  1983年   51篇
  1982年   53篇
  1980年   32篇
  1979年   35篇
  1978年   32篇
  1976年   29篇
  1974年   32篇
  1973年   30篇
  1964年   35篇
  1958年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Russian Journal of Ecology - Abstract—The study of the effect of mycorrhiza symbiosis on the transformation of carbon and nitrogen compounds in soils is important in view of the necessity to...  相似文献   
92.
Environmental Science and Pollution Research - In this work, it was analyzed the behavior of three commercial activated carbons with different textural and chemical properties to adsorb...  相似文献   
93.
94.
Concentrations of eight elements were measured in Chelonia mydas and Lepidochelys olivacea eggs collected along the Pacific coast of Panama. Manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and mercury (Hg) concentrations were similar to previous reports of these species from around the world, while lead (Pb) was lower than previous reports. Cd posed the highest health risk to people who regularly eat the eggs, with average consumption rates leading to target hazard quotients (THQ) of up to 0.35 ± 0.15. Our conclusions indicate that current turtle egg consumption in isolated, coastal Pacific communities may pose a health concern for young children, and that youth and young adults should limit their consumption of turtle eggs to reduce their total intake of nonessential metals.  相似文献   
95.
96.
The spatial structure of 10 populations of rare orchid species (Dactylorhiza incarnata, D. traunsteineri, Listera ovata) has been studied in rich fens sporadically occurring in Murmansk oblast. Two levels of plant aggregation within populations have been distinguished: (1) clusters of individuals and (2) isolated population subsets consisting of clusters. General spatial demographic features of orchid populations in the fens are small area (77 m2) and low ecological density (0.009 ind./m2). Characteristics of the population subsets (their number, area, composition, and distance to the neighboring subset) are species-specific and reflect the degree of species rarity in plant communities.  相似文献   
97.
A comparative analysis of epigenetic variation has been performed in nine European populations and population groups of the American mink. It has been shown that differentiation of samples in nonmetric characters is due mainly to endogenous processes that have occurred in introduced populations in the course of colonization of new territory by the invasive species. Environmental factors have played a secondary role, with the influence of the geographic (latitudinal) origin of a given sample being considerable and stronger than that of macroclimatic factors.  相似文献   
98.
The probable source of stone moroko, Pseudorasbora parva (Temminck & Schlegel, 1846), populations in lake- and stream-type Dnieper reservoirs was revealed. The dynamics and specific growth rates of these populations over 20 years were analyzed. The dynamic phase portrait method was used to determine the timing of stages in the process of invader naturalization and the periods when its populations were in equilibrium. The potential growth rates of P. parva populations in the Kremenchug and Dneprodzerzhinsk reservoirs were estimated.  相似文献   
99.
This paper describes how energy policy can be evaluated in practice. The goal is to make policy makers aware of how an evaluation can be based on scientific principles and to help economists appreciate how an evaluation can be performed if strong empirical evidence is lacking. We have built a basic evaluation framework and have applied this to a selection of Dutch energy policy instruments, namely production subsidies and their complementary non-financial instrument, DEN-B. Our evaluation criterion was effectiveness, defined as the extent to which policy instruments contribute to achieving policy goals. The evaluation was based on existing ex post evaluations complemented by interviews and other available data. We conclude that production subsidies and DEN-B were (partly) effective. Furthermore, the Dutch government increased effectiveness by reconsidering the design of production subsidies. We also formulate lessons for future policy evaluations and energy markets policies.  相似文献   
100.
In Bilbao (Spain), an air quality network measures sulphur dioxide levels at 4 locations. The objective of this paper is to develop a practical methodology to identify redundant sensors and evaluate a network's capability to correctly follow and represent SO2 fields in Bilbao, in the frame of a continuous network optimization process.The methodology is developed and tested at this particular location, but it is general enough to be useable at other places as well, since it is not tied neither to the particular geographical characteristics of the place nor to the phenomenology of the air quality over the area.To assess the spatial variability of SO2 measured at 4 locations in the area, three different techniques have been used: Self-Organizing Maps (SOMs), cluster analysis (CA) and Principal Component Analysis (PCA). The results show that the three techniques yield the same results, but the information obtained via PCA can be helpful not only for that purpose but also to throw light on the major mechanisms involved. This might be used in future network optimization stages. The main advantage of cluster analysis and SOMs is that they provide readily interpretable results. All the calculations have been carried out using the freely available software R.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号