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   18185篇
  免费   222篇
  国内免费   161篇
安全科学   541篇
废物处理   695篇
环保管理   2689篇
综合类   2767篇
基础理论   4960篇
环境理论   9篇
污染及防治   4729篇
评价与监测   1129篇
社会与环境   919篇
灾害及防治   130篇
  2022年   152篇
  2021年   175篇
  2020年   127篇
  2019年   190篇
  2018年   280篇
  2017年   283篇
  2016年   429篇
  2015年   285篇
  2014年   422篇
  2013年   1427篇
  2012年   520篇
  2011年   763篇
  2010年   611篇
  2009年   613篇
  2008年   788篇
  2007年   788篇
  2006年   766篇
  2005年   556篇
  2004年   633篇
  2003年   582篇
  2002年   544篇
  2001年   731篇
  2000年   520篇
  1999年   302篇
  1998年   263篇
  1997年   228篇
  1996年   249篇
  1995年   265篇
  1994年   289篇
  1993年   229篇
  1992年   263篇
  1991年   235篇
  1990年   262篇
  1989年   249篇
  1988年   209篇
  1987年   182篇
  1986年   168篇
  1985年   178篇
  1984年   206篇
  1983年   194篇
  1982年   195篇
  1981年   193篇
  1980年   141篇
  1979年   157篇
  1978年   136篇
  1977年   120篇
  1975年   123篇
  1974年   117篇
  1973年   112篇
  1972年   135篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
Scholars continue to search for solutions to shift climate change skeptics’ views on climate science and policy. However, research has shown that certain audiences are resistant to change regarding environmental issues. To explore this issue further, we examine the presence of reactance among different audiences in response to simple, yet prominently used, climate change messages. Our results show that emphasizing the scientific consensus of climate change produces reactance, but only among people who question the existence of climate change. Moreover, adding political identification to the model as an additional moderating variable shows the increases in reactance occur among Republicans who question the existence of climate change. Finally, our results show that reactance to climate change messaging may lead to backfiring effects on important outcomes tied to climate change such as risk perceptions, climate change beliefs, and support for mitigation policies.  相似文献   
142.
Laser-induced breakdown spectroscopy (LIBS) is a laser-based optical technique particularly suited for in situ surface analysis. A portable LIBS instrument was tested to detect surface chemical contamination by chemical warfare agents (CWAs). Test of detection of surface contamination was carried out in a toxlab facility with four CWAs, sarin (GB), lewisite (L1), mustard gas (HD), and VX, which were deposited on different substrates, wood, concrete, military green paint, gloves, and ceramic. The CWAs were detected by means of the detection of atomic markers (As, P, F, Cl, and S). The LIBS instrument can give a direct response in terms of detection thanks to an integrated interface for non-expert users or so called end-users. We have evaluated the capability of automatic detection of the selected CWAs. The sensitivity of our portable LIBS instrument was confirmed for the detection of a CWA at surface concentrations above 15 μg/cm2. The simultaneous detection of two markers may lead to a decrease of the number of false positive.  相似文献   
143.
Communities of benthic macroinvertebrates in drainless Lake Chany, the largest lake in Western Siberia, have been analyzed to estimate the effects of basic abiotic ecological factors (hydrophysical and hydrochemical parameters of water and the type of bottom ground) on their composition, structure, and dynamics. It has been shown that the level of development of these communities depends mainly on the water regime of the lake and also on the type of bottom ground, lake depth, and water mineral content.  相似文献   
144.
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   
145.
146.
147.
148.
The paper describes results obtained in the development of a previous research. We study here, in fast firing, the sintering behaviour and measure some properties of tiles containing a mixture of 60 wt% of paper mill sludge and 40 wt% of glass cullet. The behaviour of this material is compared to those displayed by materials obtained by the same mixture added with 10, 20 and 30 wt% of a natural red clay. In parallel, the same properties are measured also on a reference blend, which is presently used to produce commercial tiles. We show that powders containing 60 wt% of paper sludge and 40 wt% of glass cullet to which 30 wt% of clay is added give rise to materials that display a stable sintering process and have good hardness and strength and therefore could be used for the industrial production of tiles.  相似文献   
149.
150.
Twenty four hours diel cycles of arsenic speciation in Acid Mine Drainage (AMD) due to photooxidation have been reported for the first time. AMD samples were taken during 48 h (31st March and 1st April, 2005) at 6 h intervals from the effluent of a massive abandoned polymetallic sulphide mine of the Iberian Pyrite Belt (Sw Spain). Samples were preserved in situ using cationic exchange prior to analysis by coupled high performance liquid chromatography, hydride generation and atomic fluorescence spectrometry (HPLC-HG-AFS) for arsenic speciation. The results indicated the presence of inorganic arsenic species with daily means of 262mugl(-1) for As(V) and 107 microg l(-1) for As(III). No marked diel trend was observed for As(V). However, a marked diel trend was observed for As(III) in the two studied days, with maximum concentrations during nighttime (141-143 microg l(-1)) and minimum concentrations at daytime (72-77 microg l(-1)). This difference in concentration during daytime and nighttime is ca. 100%. A similar diel cycle was observed for iron. An explanation for the arsenic diel cycles observed is the light induced photooxidation of As(III) and the elimination of As(V) due to its adsorption onto Fe precipitates during the daytime. Furthermore, the diel changes in arsenic speciation emphasize the importance of designing suitable sampling strategies in AMD systems.  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