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   4222篇
  免费   29篇
  国内免费   5篇
安全科学   70篇
废物处理   161篇
环保管理   189篇
综合类   1524篇
基础理论   880篇
环境理论   8篇
污染及防治   1037篇
评价与监测   202篇
社会与环境   178篇
灾害及防治   7篇
  2022年   36篇
  2019年   41篇
  2018年   82篇
  2017年   85篇
  2016年   105篇
  2015年   91篇
  2014年   109篇
  2013年   202篇
  2012年   104篇
  2011年   183篇
  2010年   126篇
  2009年   126篇
  2008年   202篇
  2007年   170篇
  2006年   150篇
  2005年   134篇
  2004年   105篇
  2003年   98篇
  2002年   132篇
  2001年   81篇
  2000年   72篇
  1999年   50篇
  1998年   40篇
  1997年   38篇
  1996年   45篇
  1995年   47篇
  1994年   47篇
  1993年   30篇
  1992年   43篇
  1991年   37篇
  1990年   37篇
  1989年   32篇
  1986年   31篇
  1981年   30篇
  1976年   32篇
  1968年   29篇
  1967年   34篇
  1966年   30篇
  1965年   47篇
  1964年   39篇
  1963年   36篇
  1962年   31篇
  1961年   44篇
  1960年   40篇
  1959年   41篇
  1958年   46篇
  1957年   39篇
  1956年   41篇
  1955年   37篇
  1954年   40篇
排序方式: 共有4256条查询结果,搜索用时 93 毫秒
551.
Log yard run-off is a potential environmental risk, among other things because it creates an oxygen deficiency in receiving watercourses. This study was conducted to investigate the purification efficiency of soil-plant systems with couchgrass (Elymus repens) and willows (Salix sp.) when intensively irrigated with run-off from an open sprinkling system at a Norway spruce (Picea abies) log yard. The purification efficiency was determined both at the field scale (couchgrass) and in 68-L lysimeters (couchgrass and willows). Groundwater in the field and drainage water from the lysimeters were analysed for Total Organic Carbon (TOC), distillable phenols, total P, and total N. Retention of TOC, phenols and P occurred but no difference between couchgrass and willows was observed. The system had better purification capacity at the field scale than in the lysimeters.  相似文献   
552.
To estimate the effect of traffic emissions on the vegetation composition of coniferous forests near to motorways, three transects of 520 m length were studied by analysing vegetation composition, soil parameters and deposition data in the Munich-area, Southern Germany. The detected patterns suggest that motorways have an impact on the vegetation composition in the neighbourhood of roads. Depending on the wind direction, the influences of the motorways reaches up to 230 m on downwind side and up to 80 m on upwind side. The vegetation is mainly affected by the deposition of nitrogen deriving from fuel combustion and by basic substances added to road salt. By monitoring vegetation changes near to motorways, it is possible to estimate the areas where harmful alterations of the ecosystem can be expected.  相似文献   
553.
The luminescence of quartz extracted from recently fired building material is known to detect doses of few mGy and can be successfully employed in the case of large scale radiation exposures due to nuclear accidents or terrorist acts. One brick and two tiles (50-80 years range) collected from an urban settlement were used to test the realistic minimum detectable dose limits of retrospective luminescence dosimetry. Independent methods like alpha counting, beta dosimetry, gamma spectrometry and flame photometry were used for the annual dose assessment. Two approaches were employed for the evaluation of the total accrued dose: regenerative dose and additive dose. The former allows the assessment of doses due to anthropogenic sources of radiation as low as approximately 12 mGy by using 10-year-old samples, but it can be applied only in samples showing no sensitisation. The latter can be applied to any sample, however, the related uncertainty is higher and minimum detectable anthropogenic dose in young samples amounts to 20 mGy.  相似文献   
554.
There is a need for a systematic literature review focusing on adolescents’ risk perceptions in relation to risk behavior with long-term health consequences with delayed onset. The aim of this literature review was to review the results of such empirical studies, and to interpret these results from a general risk psychology perspective. Special focus was on factors influencing adolescents’ risk perceptions, and on the risk perceptions – risk behavior relationship. Literature searches were conducted in the PsycInfo, PubMed, and Cinahl databases. In total 51 journal articles were included in the review. Evidence, although inconsistent, was found for age, ethnicity, socioeconomic status, close exposure to negative outcome, perceived control, and knowledge, stereotyping and misconceptions as covariates of risk perceptions. Evidence was found both for a negative and a positive association between risk perceptions and risk behavior. The results suggest that the adolescent’s risk perception, knowledge, perceived control (response- and self-efficacy) as well as benefits and costs of health behavior must be well balanced. Any agent, such as care providers, aiming at encouraging adolescents to take active responsibility for their long term health, must be able to determine each young person’s status regarding these issues concomitantly, in order not to evoke risk denial, exaggerated unrealistic optimism, or impaired mental wellbeing.  相似文献   
555.
556.
Behavioral Ecology and Sociobiology - Predation risk is vital in determining habitat quality. But landscapes of fear are complex and dynamic, such as temperate deciduous forests characterized by...  相似文献   
557.
Environmental Geochemistry and Health - Extreme flooding in May, 2014 affected the sub-catchments of six major rivers in Serbia. The goal of the study was to evaluate the contents of potentially...  相似文献   
558.
Environmental Science and Pollution Research - The contamination left by abandoned mines demands sustainable mitigation measures. Hence, the aim of this study was to examine the phytoremediator...  相似文献   
559.
This study was conducted to investigate the degradation of propham, which is a compound that pollutes water and seriously threatens human health, by subcritical water oxidation and using H2O2 as an oxidising agent. The maximum total organic carbon removal rate of propham was obtained as 73.65% at 40 min of treatment time and 60 mM of H2O2 concentration and 373 K of temperature. In addition, response surface method based on the Box-Behnken design was applied to design the degradation experiments of propham for determination of the combined effects of process variables, namely temperature, concentration of oxidising agent and treatment time. The proposed quadratic model of propham degradation, which was examined with the analysis of variance, was used for navigating the design space. The R2 and adjusted R2 values of the model were determined as 0.9921 and 0.9819 respectively. It was shown that propham was effectively degraded, thus could be removed from the water by using an environmentally friendly method.  相似文献   
560.
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