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   42367篇
  免费   447篇
  国内免费   396篇
安全科学   1398篇
废物处理   1964篇
环保管理   5664篇
综合类   7192篇
基础理论   10680篇
环境理论   15篇
污染及防治   10402篇
评价与监测   3007篇
社会与环境   2631篇
灾害及防治   257篇
  2022年   380篇
  2021年   412篇
  2020年   269篇
  2019年   344篇
  2018年   608篇
  2017年   647篇
  2016年   997篇
  2015年   737篇
  2014年   1156篇
  2013年   3433篇
  2012年   1420篇
  2011年   1875篇
  2010年   1528篇
  2009年   1618篇
  2008年   1890篇
  2007年   1841篇
  2006年   1654篇
  2005年   1469篇
  2004年   1418篇
  2003年   1386篇
  2002年   1296篇
  2001年   1558篇
  2000年   1055篇
  1999年   706篇
  1998年   496篇
  1997年   541篇
  1996年   565篇
  1995年   629篇
  1994年   564篇
  1993年   478篇
  1992年   513篇
  1991年   498篇
  1990年   479篇
  1989年   450篇
  1988年   434篇
  1987年   336篇
  1986年   362篇
  1985年   365篇
  1984年   389篇
  1983年   366篇
  1982年   389篇
  1981年   345篇
  1980年   252篇
  1979年   284篇
  1978年   258篇
  1977年   211篇
  1975年   210篇
  1974年   224篇
  1973年   242篇
  1972年   223篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
851.

Artificial Light at Night (ALAN) is expanding worldwide, and the study of its influence remains limited mainly to documenting impacts, overlooking the variation in key characteristics of the artificial light such as its intensity. The potential dose–response of fitness-related traits to different light intensities has not been assessed in sandy beach organisms. Hence, this study explored dose-responses to ALAN by exposing the intertidal sandy beach isopod Tylos spinulosus to a range of light intensities at night: 0 (control), 20, 40, 60, 80 and 100 lx. We quantified the response of this species at the molecular (RNA:DNA ratios), physiological (absorption efficiency) and organismal (growth rate) levels. Linear and non-linear regressions were used to explore the relationship between light intensity and the isopod response. The regressions showed that increasing light intensity caused an overall?~?threefold decline in RNA:DNA ratios and a?~?threefold increase in absorption efficiency, with strong dose-dependent effects. For both response variables, non-linear regressions also identified likely thresholds at 80 lx (RNA:DNA) and 40 lx (absorption efficiency). By contrast, isopod growth rates were unrelated (unaltered) by the increase in light intensity at night. We suggest that ALAN is detrimental for the condition of the isopods, likely by reducing the activity and feeding of these nocturnal organisms, and that the isopods compensate this by absorbing nutrients more efficiently in order to maintain growth levels.

  相似文献   
852.
Environmental Science and Pollution Research - Ulcerative colitis (UC) is a common chronic, idiopathic inflammatory bowel disease associated with inflammatory perturbation and oxidative stress....  相似文献   
853.
Environmental Science and Pollution Research - Industrial sludges from wastewater treatment plants of industrial parks and a drinking water treatment plant in northern Vietnam were investigated in...  相似文献   
854.
Environmental Science and Pollution Research - Single-use plastic waste is gradually considered a potential material for circular economy. Ion exchange resin obtained from polystyrene waste by...  相似文献   
855.
Environmental Science and Pollution Research - Increasing ultraviolet (UV) radiation is causing oxidative stress that accounts for growth and yield losses in the present era of climate change....  相似文献   
856.
Environmental Science and Pollution Research - Our previous gene expression studies in a PCB-exposed cohort of young children in Slovakia revealed that early-life exposures to PCBs and other...  相似文献   
857.
Bound pesticide residues in soils: a review   总被引:34,自引:0,他引:34  
This article is a review of the current state of knowledge regarding the formation and biological/environmental significance of bound pesticide residues in soils. We begin by defining various terms used in our discussions and identifying the types/classes of pesticides which may be added to soil and interact with it. We then consider various soil properties and aspects of land management which will influence the nature and degree of the soil-pesticide association and discuss the possible physical and chemical binding mechanisms. We then move on to consider the role of microorganisms and other forms of soil biota in bound residue formation and the bioavailability of soil-borne pesticide residues. The review ends with a consideration of the significance of bound pesticide residues.  相似文献   
858.
This study represents a forensic chemical analysis to define the liability for the coastal bitumens polluting the beaches of the Mediterranean city of Alexandria. Six tar balls collected from several locations along the coast of the city were analyzed for their acyclic and polycyclic hydrocarbons as well as sulfur heterocycles using GC/FID, GC/AED and gas chromatography/mass spectrometry techniques. The analysis of one Egyptian crude oil is also included as a possible source oil. The tar ball samples were at early stages of weathering. Based on the GC traces and biomarker signatures, the tar balls could be genetically different. One sample collected from the Eastern Harbor region appears to be a Bunker C type fuel produced from Egyptian crudes. The refining process has removed the low molecular weight components. On the other hand, the wide n-alkane distribution together with the absence of an unresolved complex mixture suggests that crude oils probably from tank washings, ballast discharges or accident spills from tankers could have contributed significantly to the other tar ball samples. The distribution of source specific hopane and sterane markers revealed that the tar samples probably originate from different oil fields.  相似文献   
859.
The purpose of this research was to neutralize livestock-generated ammonia by using biofilters packed with inexpensive inorganic and organic packing material combined with multicultural microbial load at typical ambient temperatures. Peat and inorganic supporting materials were used as biofiltration matrix packed in a perfusion column through which gas was transfused. Results show the ammonia removal significantly fell in between 99 and 100% when ammonia concentration of 200 ppmv was used at different gas flow rates ranged from 0.030 to 0.060 m3 h(-1) at a fluctuating room temperature of 27.5 +/- 4.5 C (Mean +/- SD). Under these conditions, the emission concentration of ammonia that is liberated after biofiltration is less than 1 ppmv (0.707 mg m(-3)) over the period of our study, suggesting the usage of low-cost biofiltration systems for long-term function is effective at wider ranges of temperature fluctuations. The maximum (100%) ammonia removal efficiency was obtained in this biofilter was having an elimination capacity of 2.217 g m(-3) h(-1). This biofilter had high nitrification efficiencies and hence controlled ammonia levels with the reduced backpressure. The response of this biofilter to shut down and start up operation showed that the biofilm has a superior stability.  相似文献   
860.
The objective of laboratory sediment bioassays is to estimate in situ toxicity. This goal is difficult to achieve, as one of the main limitations of sediment toxicity tests is disruption of sediment geochemistry during sampling, handling and preservation. The effects of storage on the estimation of marine sediment toxicity to Crassostrea gigas embryos and larvae were investigated. Three storage methods and four storage periods were compared with three different sediment types contaminated by heavy metals, polycyclic aromatic hydrocarbons (PAHs) and both contaminants. Freezing and freeze-drying considerably increased the toxicity of decanted sediments and their elutriates as compared to the toxicity obtained with fresh sediments. Concerning the elutriates, the toxicity found with frozen and freeze-dried sediments was correlated with DOC, ammonia and PAH contents. However, the toxicity of fresh sediments kept at 4 degrees C increased with increasing duration of storage and was also correlated with the amount of ammonia in the elutriates.  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