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   22192篇
  免费   321篇
  国内免费   348篇
安全科学   711篇
废物处理   951篇
环保管理   2938篇
综合类   3728篇
基础理论   5640篇
环境理论   12篇
污染及防治   6098篇
评价与监测   1367篇
社会与环境   1273篇
灾害及防治   143篇
  2023年   131篇
  2022年   284篇
  2021年   294篇
  2020年   241篇
  2019年   215篇
  2018年   452篇
  2017年   448篇
  2016年   631篇
  2015年   485篇
  2014年   689篇
  2013年   1763篇
  2012年   878篇
  2011年   1194篇
  2010年   864篇
  2009年   937篇
  2008年   1101篇
  2007年   1125篇
  2006年   937篇
  2005年   777篇
  2004年   771篇
  2003年   703篇
  2002年   647篇
  2001年   710篇
  2000年   550篇
  1999年   355篇
  1998年   237篇
  1997年   249篇
  1996年   238篇
  1995年   298篇
  1994年   240篇
  1993年   216篇
  1992年   198篇
  1991年   201篇
  1990年   200篇
  1989年   196篇
  1988年   167篇
  1987年   145篇
  1986年   180篇
  1985年   158篇
  1984年   201篇
  1983年   161篇
  1982年   186篇
  1981年   164篇
  1980年   145篇
  1979年   159篇
  1978年   103篇
  1977年   105篇
  1975年   95篇
  1974年   96篇
  1972年   106篇
排序方式: 共有10000条查询结果,搜索用时 530 毫秒
781.
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   
782.
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   
783.
Fluctuating asymmetry (FA) of the mandible shape has been analyzed in bank voles from the zones affected by pollution from three copper smelters in the Urals. It has been shown that there is the necessity for a detailed analysis of the material, since the level of FA may depend on population parameters. Regardless of the pollution level, FA of the mandible region including the lower part of the mandibular body, ramus and processes is higher than in the diastema region. A gradient effect of toxic exposure on FA has been revealed: an increase in its level under increasing technogenic impact is clearly manifested along local pollution gradients.  相似文献   
784.
The dynamics and correlations of ecophysiological parameters have been studied in two spatially separated multispecies communities of murine rodents and ixodid tick larvae and nymphs that parasitize them. It has been shown that all the processes under consideration have nonstationary, oscillatory dynamics. The long-term dynamics of connectivity of ecophysiological characteristics within communities and their synchronization by weather–climatic factors are, by nature, wavelike processes of transitions between the states with stronger and weaker linkage between parameters, which, along with nonstationarity, can contribute to the maintenance of stability and integrity of communities.  相似文献   
785.
The population of foxes in the central regions of Yakutia has grown by a factor of four to five during the period from 2000 to 2011–2012, following an increase in the abundance of voles from the genus Microtus. A total of 130 carcasses of foxes taken in 2007–2012 have been examined. Age- and sex-related variation in morphological features has been described. The demographic structure of the population has been studied by estimating animal age from annual layers in the recording structures. Changes in female fertility and involvement in reproduction depending on age and feeding conditions have been analyzed. Changes in the composition of fox diet caused by long-term population depression in the mountain hare and their effect on the dynamics of fox abundance have been revealed. Age- and sex-related characteristics of the condition factor in foxes and sex-related differences in their dietary preferences have been demonstrated.  相似文献   
786.
Fire history within the northern larch forests of Central Siberia was studied (65 + °N). Fires within this area are predominantly caused by lightning strikes rather than human activity. Mean fire return intervals (FRIs) were found to be 112 ± 49 years (based on firescars) and 106 ± 36 years (based on firescars and tree natality dates). FRIs were increased with latitude increase and observed to be about 80 years at 64°N, about 200 years near the Arctic Circle and about 300 years nearby the northern range limit of larch stands (~71° + N). Northward FRIs increase correlated with incoming solar radiation (r = ?0.95). Post-Little Ice Age (LIA) warming (after 1850) caused approximately a doubling of fire events (in comparison with a similar period during LIA). The data obtained support a hypothesis of climate-induced fire frequency increase.  相似文献   
787.
788.
Transport infrastructure is particularly vulnerable to climate impacts as it is designed for long operational lives, and both episodic and seasonal conditions contribute to deterioration, disruption and unsafe incidents. There are some examples of adaptation in transportation design, but many communities do not have the capacity to incorporate climate change considerations into infrastructure planning and management. Researchers worked closely with the City of Prince George, in Central British Columbia, Canada, to build on existing work and explore how the City could plan, design, and maintain roads and other structures to account for climate change. A local steering committee was formed, and created and evaluated 23 potential research topics. Two focus areas were selected for further investigation and explored during a workshop with practitioners, researchers, consultants and other representatives. The workshop precipitated an investigation of projected impacts of climate change on road maintenance and road safety, and plans to explore alternative paving techniques. Outcomes of the case study provide insights regarding climate change and local transportation infrastructure, including: how researchers can engage with local experts to explore adaptation; issues local governments perceive as important; and barriers communities face as they attempt to address vulnerabilities.  相似文献   
789.
Regional Environmental Change - The use and trade of animals in traditional medicine involves many different species, some of which are threatened with extinction. Thus, evaluating biological and...  相似文献   
790.
ABSTRACT

Public apprehension over the environmental, social, and health impacts of unconventional gas drilling, or fracking, prompts various responses from oil and gas industries. Natural gas discourses operating in the Marcellus Shale Region, USA, for example, counter claims of environmental harm by emphasizing the economic growth that industry spurs. This article argues that corporate narratives operating in the Marcellus renew the jobs versus environment dichotomy by romanticizing labor identities in the region, binding Rust Belt identities to extraction in the past, present, and future of the region. The danger of this discursive move is the exclusion of alternative possibilities for working, living, and being without fossil fuel industries. I employ a critical analysis of one corporate advertising campaign, “Drilling Is Just the Beginning,” produced by the natural gas drilling company Range Resources, to demonstrate how extraction discourses construct futures that depend on shale gas development, thereby marginalizing possibilities for ecologically sensible alternatives.  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