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   20710篇
  免费   200篇
  国内免费   256篇
安全科学   542篇
废物处理   1002篇
环保管理   2460篇
综合类   2789篇
基础理论   5389篇
环境理论   4篇
污染及防治   5683篇
评价与监测   1689篇
社会与环境   1463篇
灾害及防治   145篇
  2023年   93篇
  2022年   225篇
  2021年   228篇
  2020年   155篇
  2019年   186篇
  2018年   339篇
  2017年   342篇
  2016年   541篇
  2015年   371篇
  2014年   589篇
  2013年   1781篇
  2012年   679篇
  2011年   876篇
  2010年   819篇
  2009年   802篇
  2008年   900篇
  2007年   996篇
  2006年   887篇
  2005年   728篇
  2004年   733篇
  2003年   711篇
  2002年   682篇
  2001年   920篇
  2000年   639篇
  1999年   400篇
  1998年   276篇
  1997年   248篇
  1996年   296篇
  1995年   288篇
  1994年   263篇
  1993年   240篇
  1992年   244篇
  1991年   212篇
  1990年   216篇
  1989年   223篇
  1988年   199篇
  1987年   159篇
  1986年   127篇
  1985年   140篇
  1984年   172篇
  1983年   161篇
  1982年   199篇
  1981年   139篇
  1980年   122篇
  1979年   153篇
  1978年   119篇
  1977年   107篇
  1976年   100篇
  1975年   85篇
  1974年   90篇
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
591.
Insects have been used as models for understanding animal orientation. It is well accepted that social insects such as honeybees and ants use different natural cues in their orientation mechanism. A magnetic sensitivity was suggested for the stingless bee Schwarziana quadripunctata, based on the observation of a surprising effect of a geomagnetic storm on the nest-exiting flight angles. Stimulated by this result, in this paper, the effects of a time-compressed simulated geomagnetic storm (TC-SGS) on the nest-exiting flight angles of another stingless bee, Tetragonisca angustula, are presented. Under an applied SGS, either on the horizontal or vertical component of the geomagnetic field, both nest-exiting flight angles, dip and azimuth, are statistically different from those under geomagnetic conditions. The angular dependence of ferromagnetic resonance (FMR) spectra of whole stingless bees shows the presence of organized magnetic nanoparticles in their bodies, which indicates this material as a possible magnetic detector.  相似文献   
592.
Hepatitis A causes substantial morbidity in both industrialized and non-industrialized countries and represents an important health problem in several southern Mediterranean countries. The objectives of the study were as follows: (a) to assess the occurrence of hepatitis A virus (HAV) in Tunisia through the monitoring of urban wastewaters collected at wastewater treatment plants (WTPs); (b) to characterize environmental strains; and (c) to estimate the viral load in raw and treated sewages, in order to evaluate the potential impact on superficial waters receiving discharges. A total of 150 raw and treated wastewaters were collected from three WTPs and analyzed by both qualitative (RT-PCR/nested) and quantitative (qRT-PCR) methods. Of these, 100 (66 %) were found to be positive for HAV by the qualitative assay: 68.3 % in influents and 64.7 % in effluents. The vast majority of HAV sequences belonged to sub-genotype IA, with 11 different strains detected found to be identical to clinical strains isolated from Tunisian patients with acute hepatitis. Five unique variants were also detected, not previously reported in clinical cases. Only two IB strains were found, confirming the rarity of this sub-genotype in this country. The results of the present study indicate a wide circulation of the pathogen in the population, most probably in the form of asymptomatic infections, a finding consistent with the classification of the country as having intermediate/high endemicity. Quantitative data showed high viral loads in influents (3.5E+05 genome copies/liter, mean value) as well as effluents (2.5E+05 genome copies/liter, mean value), suggesting that contaminated water could be a critical element in transmission.  相似文献   
593.
Journal of Material Cycles and Waste Management - The use of lignocellulosic fibers as fillers in polymer matrices has aroused the interest of the scientific community and industrial sectors. In...  相似文献   
594.
Journal of Material Cycles and Waste Management - Waste lubricating oil is considered to be a hazardous waste and has tremendous impact on human health and environment. The present review...  相似文献   
595.
Journal of Material Cycles and Waste Management - Leather production is a technology that boosts the economy because of its versatility and durability. However, the wastes generated throughout the...  相似文献   
596.
Journal of Material Cycles and Waste Management - The daily use of facemask to prevent virus transmission increases the negative effect on the environment because of improper waste disposal. Due to...  相似文献   
597.
Russian Journal of Ecology - Changes in the distribution of broadleaf tree species—Tilia cordata Mill., Quercus robur L., Acer platanoides L., and Ulmus glabra Huds.—in the central part...  相似文献   
598.
Russian Journal of Ecology - Climate change entails shifts in the ranges of woody plants along both latitudinal and altitudinal gradients in the boreal forest biome. In this study,...  相似文献   
599.
Environment, Development and Sustainability - The COVID-19 pandemic has caused a global emergence, and the absence of a proven vaccine or medicine has led to the implementation of measures to...  相似文献   
600.
In the Ohio River (OR), backwater confluence sedimentation dynamics are understudied, however, these river features are expected to be influential on the system’s ecological and economic function when integrated along the river’s length. In the following paper, we test the efficacy of organic and inorganic tracers for sediment fingerprinting in backwater confluences; we use fingerprinting results to evidence sediment dynamics controlling deposition patterns in confluences used for wetland and marina functions; and we quantify the spatial extent of tributary drainages with wetland and marina features in OR confluences. Both organic and inorganic tracers statistically differentiate sediment from stream and river end‐members. Carbon and nitrogen stable isotopes produce greater uncertainty in fingerprinting results than inorganic elemental tracers. Uncertainty analysis of the nonconservative tracer term in the organic matter fingerprinting application estimates an apparent enrichment of the carbon stable isotopes during instream residence, and the nonconservativeness is quantified with a statistical approach unique to the fingerprinting literature. Wetland and marina features in OR confluences impact 42% and 11% of tributary drainage areas, respectively. Sediment dynamics show wetland and marina confluences experience deposition from river backwaters with longitudinally linear and nonlinear patterns, respectively, from sediment sources.  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