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   531篇
  免费   19篇
  国内免费   69篇
安全科学   9篇
废物处理   22篇
环保管理   54篇
综合类   149篇
基础理论   120篇
污染及防治   172篇
评价与监测   70篇
社会与环境   20篇
灾害及防治   3篇
  2023年   5篇
  2022年   11篇
  2021年   14篇
  2020年   19篇
  2019年   13篇
  2018年   9篇
  2017年   20篇
  2016年   24篇
  2015年   15篇
  2014年   24篇
  2013年   64篇
  2012年   12篇
  2011年   20篇
  2010年   30篇
  2009年   27篇
  2008年   30篇
  2007年   27篇
  2006年   25篇
  2005年   24篇
  2004年   19篇
  2003年   14篇
  2002年   19篇
  2001年   21篇
  2000年   11篇
  1999年   9篇
  1998年   3篇
  1997年   2篇
  1996年   5篇
  1995年   9篇
  1994年   6篇
  1993年   7篇
  1992年   3篇
  1991年   4篇
  1989年   4篇
  1988年   4篇
  1987年   3篇
  1986年   2篇
  1982年   5篇
  1979年   2篇
  1975年   3篇
  1974年   2篇
  1971年   4篇
  1966年   4篇
  1965年   5篇
  1964年   4篇
  1963年   5篇
  1961年   6篇
  1960年   2篇
  1958年   2篇
  1955年   2篇
排序方式: 共有619条查询结果,搜索用时 0 毫秒
11.
12.
13.
以宝钢不锈钢转炉(AOD)除尘新技术产生为背景,结合工程项目论述了除尘新技术在不锈钢转炉上应用的基本原理,并对其优点、实用性、实施效果以及产生的效益进行了客观评价,同时介绍了新技术在项目实际运行中取得的经验.  相似文献   
14.
膜生物反应器去除废水中阴离子表面活性剂的研究   总被引:5,自引:0,他引:5  
阴离子表面活性剂是环境中分布广泛且具有代表性的一类有机污染物.采用分置式膜生物反应器(MBR)进行去除模拟废水中阴离子表面活性荆(LAS)的实验,结果表明:MBR对阴离子表面活性荆的去除率高于90%.同时考察了阴离子表面活性荆生物降解的影响因素,确定其适宜降解条件为:气体流量为0.3m3/h、活性污泥浓度为6948mg/L.初步探讨了降解动力学和降解机理,研究表明对阴离子表面活性剂的去除符合拟一级反应动力学过程,且生物降解对其去除起主要作用.  相似文献   
15.
Sathaye  J.A.  Makundi  W.R.  Andrasko  K.  Boer  R.  Ravindranath  N.H.  Sudha  P.  Rao  S.  Lasco  R.  Pulhin  F.  Masera  O.  Ceron  A.  Ordonez  J.  Deying  X.  Zhang  X.  Zuomin  S. 《Mitigation and Adaptation Strategies for Global Change》2001,6(3-4):185-211
This paper summarizes studies of carbon (C) mitigation potential and costs of about 40 forestry options in seven developing countries. Each study uses the same methodological approach – Comprehensive Mitigation Assessment Process (COMAP) – to estimate the above parameters between 2000 and 2030. The approach requires the projection of baseline and mitigation land-use scenarios. Coupled with data on a per ha basis on C sequestration or avoidance, and costs and benefits, it allows the estimation of monetary benefit per Mg C, and the total costs and carbon potential. The results show that about half (3.0 Pg C) the cumulative mitigation potential of 6.2 Petagram (Pg) C between 2000 and 2030 in the seven countries (about 200× 106 Mg C yr-1) could be achieved at a negative cost and the remainder at costs ranging up to $100 Mg C-1. About 5 Pg C could be achieved, at a cost less than $20 per Mg C. Negative cost potential indicates that non-carbon revenue is sufficient to offset direct costs of these options. The achievable potential is likely to be smaller, however, due to market, institutional, and sociocultural barriers that can delay or prevent the implementation of the analyzed options.  相似文献   
16.
蓟运河汞污染化学地理特征   总被引:1,自引:0,他引:1  
通过对蓟运河汞污染化学地理研究,查清了河水沉积物中汞和甲基汞的含量范围,水平和垂直变化,以及空间分布;研究了汞存在的形态;揭示了汞在河流中的富集区;作出了河流汞污染状况的分区,初步提出了治理河道汞污染的途径。  相似文献   
17.
The impact of SO(2) on superoxide dismutase (SOD) and the ascorbate-glutathione cycle was investigated in a tolerant (cv. Punjab-1) and a sensitive (cv. JS 7244) cultivar of soybean (Glycine max (L.) Merr.). In spite of SO(2) stimulated SOD activities in both the cultivars, only cv. JS 7244 has significantly enhanced Malondialdehyde (MDA) contents. This differential response was attributed to the ability of cv. Punjab-1 to enhance glutathione reductase (GR) activity and to maintain high GSH/GSSG and ASA/DHA ratios. Post-fumigation analysis indicated the ability of cv. Punjab-1 to maintain SO(2)-enhanced antioxidants, whilst they declined in cv. JS 7244 the moment fumigation was terminated. Exposure of SO(2)-acclimated plants (cv. Punjab-1) with their enhanced antioxidants to 250 microg m(-3) SO(2) for 6 h exhibited no enhanced cellular injury (MDA content) when compared to that of control plants with their normal antioxidant levels. These results indicate a relation between the ability of a plant to maintain reduced glutathione (GSH) and ascorbate (ASA) and SO(2) tolerance, and they also present evidence for the ability of plants, with elevated antioxidants, to tolerate SO(2)-induced oxygen-free radical toxicity.  相似文献   
18.
随着我国油田相继进入开发后期,传统的滤料及设备过滤精度已不能满足注水的要求。因此,研究并开发了具有一定抗油污能力的新型过滤材料,设计了新型的超精细过滤器系列产品。对滤料进行的室内实验结果表明,在开始过滤的近10h内,过滤后的水中含油量基本上满足注水的水质要求。在开始过滤的近20h内,滤层的水头损失随时间的变化较为平缓;随着过滤时间的延长,水头损失变化加剧。从现场实验可以看出,所设计的过滤器有良好的过滤性能和抗冲击能力。新型过滤材料的研究成功解决了油田含油污水精细过滤的问题,新型过滤器也是含油污水超精细过滤的理想产品。  相似文献   
19.
Despite the critical role of government agencies in decentralizing natural resource governance, little work to date has focused on the organizational aspects of the responsible government bureaucracies. Based on a qualitative investigation of the perspectives of Forest Department employees involved in India's Joint Forest Management (JFM) program, this paper aims to provide an understanding of these internal dynamics. Elaborating on why bureaucracies with a learning orientation are essential if participatory natural resource management is to succeed, the paper underlines the constraints to transforming forest agencies' hierarchical work cultures. Foresters describe JFM as a radical departure from traditional forest governance, but suggest that corresponding transformation within the Forest Department has not occurred. Foresters cite as reasons: (1) a target-based incentive system that leaves little room for establishing the relationships with local people needed for collaborative management; (2) rigid rules and regulations that prevent the flexibility needed for adaptive, site-specific problem-solving; (3) a hierarchical, top-down style of communication that prevents the upper administration from learning what is happening on the ground and stifles initiative by field staff; (4) the need for a committed leadership to reverse this hierarchical culture. They point to the few such team-oriented leaders as the key to transforming the Forest Department and enabling participatory forest management to succeed. The authors also recommend accompanying changes in training and reward systems.  相似文献   
20.
Indian bullfrog Haplobatrachus tigerinus (Daudin) was exposed to sublethal dose (1/3 of LC50 I.E. 1.166 mg/kg) of fenvalerate technical grade and the effect was studied on the specific activity of acetyl cholinesterase in the different tissues of frog viz., brain, muscle, liver, kidney and testis at different time periods viz., 3,6, 12, 24, 48 and 72 hours. The inhibition of specific activity of acetyl cholinesterase was in the order of kidney > brain > muscle > liver > testis. A significant inhibition was noticed in kidney at 12 hours (-64.33%) and no effect was noticed at 3 hours in testis (+0.67%). The AChE activity was inhibited in first three hours of administration of fenvalerate in all the tissue tested. The inhibition continued upto 6 hours or 2 hours in different tissue but the recovery was started by 24 hours and almost completed by 72 hours.  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