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   313篇
  免费   18篇
  国内免费   8篇
安全科学   11篇
废物处理   12篇
环保管理   74篇
综合类   29篇
基础理论   81篇
污染及防治   80篇
评价与监测   40篇
社会与环境   11篇
灾害及防治   1篇
  2023年   3篇
  2022年   4篇
  2021年   5篇
  2020年   2篇
  2019年   10篇
  2018年   13篇
  2017年   8篇
  2016年   9篇
  2015年   7篇
  2014年   7篇
  2013年   38篇
  2012年   13篇
  2011年   12篇
  2010年   9篇
  2009年   8篇
  2008年   12篇
  2007年   18篇
  2006年   18篇
  2005年   10篇
  2004年   7篇
  2003年   14篇
  2002年   8篇
  2001年   8篇
  2000年   6篇
  1999年   5篇
  1998年   3篇
  1996年   3篇
  1995年   5篇
  1994年   5篇
  1993年   4篇
  1992年   3篇
  1991年   4篇
  1990年   5篇
  1987年   6篇
  1985年   3篇
  1984年   11篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1979年   8篇
  1978年   1篇
  1977年   3篇
  1975年   2篇
  1974年   1篇
  1973年   3篇
  1971年   1篇
  1969年   1篇
  1966年   1篇
  1965年   1篇
  1964年   1篇
排序方式: 共有339条查询结果,搜索用时 109 毫秒
331.
332.
Cyanide (CN) residue levels were determined in samples of extracted honey, comb honey and was cappings at 1 hr, 24 hr, and 48 hr intervals after destroying the bees in honey bee colonies with normal (ca. 8.5 g) and twice normal (ca. 17 g) doses of CyanogasR A-dust. Applications of CyanogasR A-dust, administered by means of a dust pump at normal and twice normal doses, gave an average residue of 0.01 and 0.04 microgram CN/g of extracted honey, 0.01 and 0.02 microgram CN/g of comb honey and 0.04 and 0.06 microgram CN/g of wax cappings, respectively. When the CyanogasR A-dust (ca. 17 g) was placed on a tray and placed on the bottom board of the hive, the average residue levels for extracted honey, comb honey and wax cappings were less than 0.004, 0.01 and 0.02 microgram CN/g, respectively. Random honey samples from beekeepers, who used CyanogasR to destroy bees, had a median level of 0.031 microgram CN/g, whereas honey from a packing plant and other commercial samples contained less than 0.004--0.026, median less than 0.004 microgram CN/g. Based on residue data from this study, the temporary registration for CyanogasR, to kill honey bees after crop removal, was revised to a full registration in May 1977.  相似文献   
333.
A wide variety of hypotheses has been proposed to explain the structural diversity in bird song repertoires. Song diversity is frequently described in terms of song “types” or within-type “variants.” Male Puget Sound white-crowned sparrows, Zonotrichia leucophrys pugetensis, produce variants of their single adult song type by altering the number of repetitions of syllables in the terminal trill. We tested whether variation in trill length correlated with distance to the receiver and with signaling context as predicted by the eavesdropping avoidance hypothesis and the strategic signaling hypothesis. In accordance with the eavesdropping avoidance hypothesis, males sang variants with shorter trills, and sang quieter and less frequently when near their mate during the incubation phase than during spontaneous singing while unpaired. Males also sang variants with short trills, but at a high rate and variable amplitude when within 10 m of an opponent during close male–male territorial interactions. In agreement with the strategic signaling hypothesis, males decreased trill length immediately before chasing an opponent, but did not change length consistently prior to flight. We conclude that the occurrence of short quiet songs sung near the mate agrees with predictions of the eavesdropping avoidance hypothesis, while short songs sung near other males are best explained by the strategic signaling hypothesis. Trill length variation may be a conventional signal of aggressive intentions in male–male contests stabilized by receiver-imposed retaliation costs.  相似文献   
334.
This paper presents and tests a model of the impact of secure and insecure attachment styles (secure, counterdependent, and overdependent) on citizenship behavior and workplace deviance behavior through vigor at work. Employees who exhibit secure attachment styles are proposed to exhibit more vigor at work because of more effective use of physical, emotional, and cognitive resources which translates into increased organizational citizenship behaviors (OCBs) and decreased deviance. Insecurely attached employees are hypothesized to exhibit the opposite pattern. In a sample of 331 repair generalists in a large building facilities and maintenance organization, results indicate that attachment styles indirectly predicted OCBs and deviance through vigor. Implications of these results for attachment style, vigor at work, OCBs, and deviance are discussed. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
335.
336.
Toxicity of two azo dyes (Reactive Orange 16 (RO16); Congo Red (CR)) and two anthraquinone dyes (Remazol Brilliant Blue R (RBBR); Disperse Blue 3 (DB3)) were compared using bacterium Vibrio fischeri, microalga Selenastrum capricornutum and ciliate Tetrahymena pyriformis. The following respective endpoints were involved: acute toxicity measured as bacterial luminescence inhibition, algal growth inhibition, and the effects on the protozoa including viability, growth inhibition, grazing effect and morphometric effects. In addition, mutagenicity of the dyes was determined using Ames test with bacterium Salmonella typhimurium His(-). DB3 dye was the most toxic of all dyes in the bacterial, algal and protozoan tests. In contrast to other dyes, DB3 exhibited mutagenic effects after metabolic activation in vitro in all S. typhimurium strains used. Of the methods applied, the algal test was the most sensitive to evaluate toxicity of the dyes tested.  相似文献   
337.
Analysis of serum, whole blood and liver tissue samples from Kafue lechwe in the Lochinvar National Park of Zambia for suspected endocrine disrupting compounds revealed high concentrations for some of the compounds. 45 samples of serum, whole blood and liver tissue were extracted by liquid-liquid extraction followed by an analysis using Gas Chromatography-Electron Capture Detection (GC-ECD). The following endocrine disruptors were analyzed: deltamethrin, aldrin, endosulfan, dieldrin, pp-DDD, heptachlor, d-t-allethrin, pp-DDE, endrin and pp-DDT. For all the samples, dieldrin showed the highest concentration ranging from 1.7 to 44.4 microg/ml in serum and whole blood sample extracts and 0.10-5.1 microg/g wet weight in liver sample extracts. The most frequently detected was deltamethrin in 62% of the samples. Percent recoveries in spiked laboratory blanks ranged between 60% and 100% while calculated detection limits ranged from 0.004 to 0.21 microg/ml for all the endocrine disruptors evaluated. Where endocrine disruptors were detected, the concentrations of most of them far exceeded the maximum residue limits (MRLs) and the extraneous maximum residue limits (EMRLs) set by the Codex Alimentarius of the United Nations (UN), Food and Agricultural Organization (FAO).  相似文献   
338.
Earthworms and soils were collected from 20 diverse sites in Maryland, Pennsylvania, and Virginia, and were analyzed for Pb, Cu, Zn, Cd, Cr, As, and Se. Correlation coefficients relating concentrations of the elements in earthworms to concentrations in soil were low (–0.20<r<+0.57). Species differences and ecological variables contributed to the variability in concentrations of these elements in earthworms. The maximum concentrations of Pb (2100 ppm), Zn (1600 ppm), Cd (23 ppm) and Se (7.6 ppm) detected in earthworms were in the range reported to be toxic to animals fed diets containing these elements; however, even in the absence of any environmental contamination, some species of earthworms may contain high concentrations of Pb, Zn, and Se. Earthworms of the genus Eisenoides, for example, were exceptional in their ability to concentrate Pb. When earthworms are used as indicators of environmental contamination, it is important to identify the species, to report the soil characteristics, and to collect similar earthworms from very similar but uncontaminated soil.  相似文献   
339.
Environmental Science and Pollution Research - The expansion of agricultural activities causes habitat loss and fragmentation and the pollution of natural ecosystems through the intense use of...  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