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   1925篇
  免费   193篇
  国内免费   237篇
安全科学   711篇
废物处理   31篇
环保管理   266篇
综合类   876篇
基础理论   150篇
污染及防治   141篇
评价与监测   84篇
社会与环境   52篇
灾害及防治   44篇
  2024年   3篇
  2023年   28篇
  2022年   57篇
  2021年   47篇
  2020年   46篇
  2019年   46篇
  2018年   42篇
  2017年   70篇
  2016年   60篇
  2015年   114篇
  2014年   95篇
  2013年   104篇
  2012年   179篇
  2011年   165篇
  2010年   93篇
  2009年   121篇
  2008年   93篇
  2007年   115篇
  2006年   120篇
  2005年   90篇
  2004年   70篇
  2003年   77篇
  2002年   64篇
  2001年   57篇
  2000年   64篇
  1999年   44篇
  1998年   58篇
  1997年   42篇
  1996年   30篇
  1995年   16篇
  1994年   22篇
  1993年   25篇
  1992年   21篇
  1991年   10篇
  1990年   6篇
  1989年   3篇
  1988年   2篇
  1987年   9篇
  1986年   2篇
  1985年   5篇
  1984年   5篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1980年   2篇
  1979年   6篇
  1978年   5篇
  1977年   5篇
  1975年   5篇
  1970年   1篇
排序方式: 共有2355条查询结果,搜索用时 31 毫秒
51.
酸雨对种子萌发影响的实验研究   总被引:1,自引:0,他引:1  
采用PH值2.5、3.0、3.5、4.5的酸雨处理小麦种子,观察种子的萌发率、平均萌发天数和萌发势。结果表明:酸雨对种子的萌发率和平均萌发无显著影响,但对种子萌发势有显著影响。  相似文献   
52.
钢铁冷锻加工中的磷化工序一般采用酸洗法去除毛坯上的氧化膜。现介绍用抛丸处理工艺替代酸洗方法,可以大幅度减少工业污染,降低生产成本,提高工艺质量。  相似文献   
53.
岩溶山区的煤炭开采必将时生态环境造成影响和破环.为确保煤炭生产与生态环境的协调发展,根据岩溶山区资源环境与生态特点。采取积极有效的综合防治措施,以及收取环境恢复治理保证金的建议,可望通过实践取得成效.  相似文献   
54.
Major mining companies have recently embraced the sustainable development paradigm, in seeking to improve their competitiveness and increase shareholder returns. Successful mine closure is one important element of this process. Improved performance in this area is essential if surrounding communities are to see mining companies as responsible corporate and social partners.
In Indonesia, the new approach has coincided with the development of specific mine closure legislation. To facilitate the legislation, a consortium of mining companies joined to form the Industry Mine Closure Steering Committee. This Committee has lobbied the Government, actively negotiating to incorporate sustainable development ideals and practices into the new legislation. The Committee's aim has been to foster continued development of the mining industry, while taking account of variation in environmental, social and community conditions. In describing the process, this article seeks to provide guidance for the development of mine closure legislation in other nations.  相似文献   
55.
从我国非煤矿山安全生产立法、安全生产管理体制、监察执法、群众监督、宣传教育、科研、矿山企业等方面与国外矿业进行了对比分析,分析了我国非煤矿山存在的问题以及与国外的差距,最后分析了产生问题与差距的原因。  相似文献   
56.
Open-cast lignite mining in the Lusatian mining district resulted in rehabilitated mine soils containing up to four organic matter types: (1) recent plant litter, (2) lignite deposited by mining activity, (3) carbonaceous ash particles deposited during amelioration of the lignite-containing parent substrate and (4) airborne carbonaceous particles deposited during contamination. The influence of lignite-derived carbon types on the organic matter development and their role in the soil carbon cycle was unknown. This paper presents the findings obtained during a six year project concerning the impact of lignite on soil organic matter composition and the biogeochemical functioning of the ecosystem. The organic matter development after rehabilitation was followed in a chronosequence of rehabilitated mine soils afforested in 1966, 1981 and 1987. A differentiation of the organic matter types and an evaluation of their role within the ecosystem was achieved by the use of 14C activity measurements, 13C CPMAS NMR spectroscopy and wet chemical analysis of plant litter compounds. The results showed that the amount and degree of decomposition of the recent organic matter derived from plant material of the 30 year old mine soil was similar to natural uncontaminated forest soil which suggests complete rehabilitation of the ecosystem. The decomposition and humification processes were not influenced by the presence of lignite. On the other hand it was shown that lignite, which was thought to be recalcitrant because of its chemical structure, was part of the carbon cycle in these soils. This demonstrates the need to elucidate further the stabilisation mechanisms of organic matter in soils.  相似文献   
57.
Foreword Asoneofthethreegreatdiscoveriesin 1 970s ,thefractaltheoryhasbeenwidelyappliedinmanyfieldsconcerningthesciencesofnatureandthehumanities .Atpresent ,thefractaltheoryhasbeenappliedintherelatedanalysisofwatersystemordisaster .However ,thestud iesonnatureofrelationshipbetweenthewholewatersysteminChinaanddisasterfractalanaly sisarestillintheirinitialperiod .Thepaperpresentsafractaldimensionof 7drainagebasinsandthefloodinChinaaswellastheirpossiblerelations .Itishopedthatthepaperwouldbehe…  相似文献   
58.
本文在综述四川酸性降水范围、发展趋势预测的基础上,根据野外调查、现场考察和有关资料,阐述了酸雨形成的多种污染源及其对农业生态系统的危害。着重分析和论证了酸沉降(含酸雨、酸雾)对农作蔬菜的影响,并对酸沉降形成的主要几种污染影响范围和造成的经济损失采用分项估算法。估算公式为:S农损=D粮损×g×J+E蔬损×g×J+F油损×g×J,式中D、E、F分别代表粮食、蔬菜、油菜受酸沉降污染危害影响面积,g为每亩面积减产数量,J为单位产量价格。根据公式估算,经济损失为059-066亿元/年,取平均值≈S农损,总共为063亿元/年。  相似文献   
59.
ABSTRACT: A study was conducted to determine the effects of mining and reclaiming originally undisturbed watersheds on surface-water hydrology in three small experimental watersheds in Ohio. Approximately six years of data were collected at each site, with differing lengths of premining (Phase 1), mining and reclamation (Phase 2), and post-reclamation (Phase 3) periods. Mining and reclamation activities showed no consistent pattern iii base-flow, and caused slightly more frequent higher daily flow volumes. Phase 2 activities can cause reductions in seasonal variation in double mass curves compared with Phase 1. Restoration of seasonal variations was noticeably apparent at one site during Phase 3. The responses of the watersheds to rainfall intensities causing larger peak flow rates generally decreased due to mining and reclamation, but tended to exceed responses observed in Phase 1 during Phase 3. Natural Resources Conservation Service (NRCS) curve numbers increased due to mining and reclamation (Phase 2), ranging from 83 to 91. During Phase 3, curve numbers remained approximately constant from Phase 2, ranging from 87 to 91.  相似文献   
60.
ABSTRACT: Pesticides in stormwater runoff, within the Sacramento River Basin, California, were assessed during a storm that occurred in January 1994. Two organophosphate insecticides (diazinon and methidathion), two carbamate pesticides (molinate and carbofuran), and one triazine herbicide (simazine) were detected. Organophosphate pesticide concentrations increased with the rising stage of the hydrographs; peak concentrations were measured near peak discharge. Diazinon oxon, a toxic degradation product of diazinon, made up approximately 1 to 3 percent of the diazinon load. The Feather River was the principal source of organophosphate pesticides to the Sacramento River during this storm. The concentrations of molinate and carbofuran, pesticides applied to rice fields during May and June, were relatively constant during and after the storm. Their presence in surface water was attributed to the flooding and subsequent drainage, as a management practice to degrade rice stubble prior to the next planting. A photo-degradation product of molinate, 4-keto molinate, was in all samples where molinate was detected and made up approximately 50 percent of the total molinate load. Simazine, a herbicide used in orchards and to control weeds along the roadways, was detected in the storm runoff, but it was not possible to differentiate the two sources of that pesticide to the Sacramento River.  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