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   55643篇
  免费   533篇
  国内免费   476篇
安全科学   1474篇
废物处理   2296篇
环保管理   7243篇
综合类   8409篇
基础理论   15640篇
环境理论   28篇
污染及防治   14010篇
评价与监测   3762篇
社会与环境   3427篇
灾害及防治   363篇
  2022年   430篇
  2021年   447篇
  2020年   324篇
  2019年   415篇
  2018年   1097篇
  2017年   1066篇
  2016年   1395篇
  2015年   946篇
  2014年   1331篇
  2013年   4202篇
  2012年   1733篇
  2011年   2716篇
  2010年   2167篇
  2009年   2207篇
  2008年   2582篇
  2007年   2882篇
  2006年   2133篇
  2005年   1827篇
  2004年   1762篇
  2003年   1722篇
  2002年   1697篇
  2001年   2129篇
  2000年   1512篇
  1999年   931篇
  1998年   714篇
  1997年   699篇
  1996年   750篇
  1995年   782篇
  1994年   719篇
  1993年   658篇
  1992年   668篇
  1991年   612篇
  1990年   622篇
  1989年   643篇
  1988年   559篇
  1987年   489篇
  1986年   452篇
  1985年   487篇
  1984年   509篇
  1983年   518篇
  1982年   520篇
  1981年   434篇
  1980年   390篇
  1979年   455篇
  1978年   370篇
  1977年   334篇
  1976年   308篇
  1975年   299篇
  1973年   295篇
  1972年   301篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
151.
152.
153.
In a 1981 survey of 436 Florida citrus growers, 27 pesticide related poisoning incidents were reported that were to have taken place within one year of the interview date. From these reports it is possible to estimate that there are 376 citrus fieldworker related poisonings per year in Florida. This number of estimated poisonings may be developed into an incidence rate of 113 fieldworker poisonings per 10,000 fieldworkers.  相似文献   
154.
Community evacuation following a chlorine release, Mississippi   总被引:1,自引:0,他引:1  
On 7th September 1986, four miles north of Collins, Mississippi, a train transporting chlorine derailed. Two cars ruptured and gas escaped. As a result, 100 families were evacuated. To study the evacuation process, we conducted person-to-person interviews with sixty-two families staying in the evacuation center. Only 52.5% of the families received their first directive to evacuate directly from police or other officials. Delays in evacuating tended to be shorter when people were warned by the police and were told the reason for evacuating. Lack of personal transportation and preexisting health problems resulted in delays in evacuation. Concerns about evacuation included fear of looting, lack of a place to go, lack of transportation, difficulty in moving with children and elderly persons, and the need to take care of pets. One third of the interviewees reported feeling panic. Community evacuation procedures would be improved if: (1) officials contact all households directly; (2) the warning message addresses people's concerns; and (3) transportation is provided.  相似文献   
155.
ABSTRACT: This paper describes the formulation of an Index of Water Quality to evaluate the level of pollution in fresh water. A Four-Round Delphi equation, using a panel of seven nationally recognized water scientists, was performed to ascertain the pollutants to be included in the index, the relationship between the quantity of these pollutants in the water and the resulting quality of the water, and the importance of each pollution variable to each water use as well as to overall pollution. A multiplicative index was used to bring the pollutants together into one system.  相似文献   
156.
157.
   Global change, i.e. the mega-process radically transforming the relationship between nature and human civilization since the end of World War II, is investigated from the point of view of systems analysis. It is argued that this unbridled process should rather be domesticated by planetary control strategies transpiring from a new science called “geocybernetics”. The formal aspects of geocybernetic theory are sketched and illustrated in a tutorial theatre world reflecting the overall environment and development problematic. Within this setting a straightforward operationalization of the sweeping “sustainable development” ideal through a set of concise paradigms can be achieved. Evidence is provided that geocybernetics is actually feasible on the basis of earth system modelling and fuzzy-control techniques.  相似文献   
158.
159.
The effectiveness of inorganic alumino-silicate sorbents (alumina and kaolinite) to adsorb airborne lead and cadmium from the effluent stream of a simulated waste incinerator was studied. A 20 kW (68,000 BTU/h) flow reactor was used to achieve the temperature and residence times typical of a waste incinerator. Solutions containing lead or cadmium were introduced yielding airborne metals concentrations between 15 and 150 ppm. Gas samples were drawn into a particle impactor that collected the airborne particles and condensed phase metal aerosols, separating them into ten size ranges from 0.2 μm to greater than 10 μm. Metals to sorbent mass ratios between 0.03 and 1.56 were investigated. Scavenging efficiency increased as the ratio of sorbent to injected metal mass was increased. The scavenging efficiencies were as high as 76% for lead scavenged by kaolinite to as low as 14% for cadmium scavenged by alumina.  相似文献   
160.
The presence of maternal cells in fetal samples constitutes a serious potential source for prenatal misdiagnosis. Here we present our approach for detecting maternal cell contamination (MCC) at prenatal diagnosis for eight monogenic disorders (autosomal recessive: β-thalassaemia, sickle-cell anaemia, cystic fibrosis, prelingual deafness; autosomal dominant: achondroplasia, Huntington disease, myotonic dystrophy, neurofibromatosis type I; X-linked: spinobulbar muscular atrophy). Our aim was to apply a simple and low-cost approach, which would easily and accurately provide information on the fetal tissue MCC status. MCC testing was applied to cases of recessive inheritance where the primary mutation screening of the fetus revealed the presence of the maternal mutation, to cases concerning dominant inheritance and to cases of multiple gestation. The potential presence of maternal cells was determined by the amplification of the 3′-HVR/APO B, D1S80, THO1 and VNTRI of vWf polymorphic loci, which have previously demonstrated high heterozygosity in Caucasians. Among 135 prenatal diagnoses, 44 finally needed to be tested for MCC (32.6%). MCC was detected in four cases, where DNA was isolated directly from chorionic villi samples (CVS), and in one case with DNA isolated directly from amniotic fluid (AF). In almost 90% of cases a simple test of one polymorphic locus provided sufficient information about MCC. The choice of the appropriate locus is therefore essential, while the simultaneous screening of both parents provides the means for distinguishing non-informative sites about MCC. Copyright © 2002 John Wiley & Sons, Ltd.  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