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   1519篇
  免费   57篇
  国内免费   159篇
安全科学   116篇
废物处理   84篇
环保管理   884篇
综合类   369篇
基础理论   90篇
污染及防治   58篇
评价与监测   65篇
社会与环境   15篇
灾害及防治   54篇
  2024年   1篇
  2023年   9篇
  2022年   14篇
  2021年   16篇
  2020年   23篇
  2019年   5篇
  2018年   10篇
  2017年   12篇
  2016年   18篇
  2015年   14篇
  2014年   19篇
  2013年   25篇
  2012年   16篇
  2011年   30篇
  2010年   29篇
  2009年   24篇
  2008年   57篇
  2007年   13篇
  2006年   21篇
  2005年   17篇
  2004年   38篇
  2003年   70篇
  2002年   159篇
  2001年   142篇
  2000年   174篇
  1999年   134篇
  1998年   103篇
  1997年   80篇
  1996年   214篇
  1995年   60篇
  1994年   17篇
  1993年   12篇
  1992年   5篇
  1991年   5篇
  1990年   4篇
  1989年   9篇
  1988年   3篇
  1987年   2篇
  1986年   1篇
  1985年   22篇
  1984年   38篇
  1983年   35篇
  1982年   4篇
  1981年   2篇
  1980年   7篇
  1978年   5篇
  1977年   1篇
  1975年   1篇
  1971年   14篇
  1967年   1篇
排序方式: 共有1735条查询结果,搜索用时 31 毫秒
411.
IntroductionThestudyofmodernsoilzoologyhasenteredintoastageofbiologicalproductivityandtherelationbetweenhumanandenvironment.P?..  相似文献   
412.
Vogt J 《Disasters》1983,7(3):191-193
Until 1975 or so, scientists' knowledge of the major earthquake of 1660 in the Pyrenees (in Bigorre) was largely restricted to the meagre information repeated in the classical catalogues. Useful material published in local learned journals was mostly unknown, and has only been unearthed and interpreted since 1976, when two year's work of analysis was started for the "Projet Sismo-tectonique" in France. During and since that project, further routine work necessary for the revision of the historical seismicity of France, has brought to light a new wealth of information from archive sources. This new knowledge, at least from the French side, is used as the basis for a brief macroseismic review of the event north of the Pyrenees, putting forward proposals for the isoseismal lines. Emphasis is placed on the number and quality of the sources, some of which are quoted for evidence of major rockfalls in the meizoseismal region and the wide extent of the felt area, as far north as Salnt-Maixent in Poitou.  相似文献   
413.
Investigations were carried out to determine the effect of zeolite type A on metal removal by activated sludge using laboratory activated sludge simulations. They were operated at constant aerator sludge age and settler surface loading. Different concentrations of raw zeolite and zeolite extracted from washing powder (0, 15, 30, 60, 120 mgl?1) were introduced into the simulations. The zeolite was added at two degrees of calcium exchanged for sodium, 25 and 75% of the maximum exchange capacity. Metals were added at concentrations typical of mixed domestic-industrial waste waters. The results show that there was no adverse effect on metal removal by the laboratory activated sludge simulations in the presence of zeolite type A.  相似文献   
414.
The catalytic ozonation treatment of secondary biochemical effluent for papermaking wastewater by Ag-doped nickel ferrite was investigated. Ag-doped catalysts prepared by sol-gel method were characterized, illustrating that Ag entirely entered the crystalline of NiFe2O4 and changed the surface properties. The addition of catalyst enhanced the removal efficiency of chemical oxygen demand and total organic carbon. The results of gas chromatography-mass spectrometer, ultraviolet light absorbance at 254 nm and three-dimensional fluorescence excitation-emission matrix suggested that aromatic compounds were efficiently degraded and toxic substances, such as dibutyl phthalate. In addition, the radical scavenging experiments confirmed the hydroxyl radicals acted as the main reactive oxygen species and the surface properties of catalysts played an important role in the reaction. Overall, this work validated potential applications of Ag-doped NiFe2O4 catalyzed ozonation process of biologically recalcitrant wastewater.  相似文献   
415.
416.
研究了投加生物催化剂维生素B12(VB12)对厌氧活性污泥还原降解8:2氟调聚醇(8:2FTOH)的影响.结果表明,投加VB12能够改变厌氧活性污泥还原降解8:2FTOH的动力学特性并增加其最终去除率,但投加量存在上下限:当VB12投加量≤1mg/L时,8:2FTOH最终去除量无显著增加;当VB12投加量≥5mg/L时,8:2FTOH最终去除量也不再持续增加.投加所有剂量的VB12均可显著增加8:2FTOH的最终脱氟率.投加VB12对厌氧活性污泥还原降解8:2FTOH去除率和脱氟率的影响并不一致.此外,投加较高浓度的VB12可以抑制厌氧污泥还原降解8:2FTOH过程中多氟代化合物等中间降解产物的积累,提高全氟代化合物等终态降解产物的产率,同时有利于增加8:2FTOH的矿化脱氟率,但却导致了更低的总物质的量回收率.  相似文献   
417.
黑水虻能够有效取食厨余垃圾等有机固体废弃物,其自身转化为昆虫蛋白和脂肪等生物质,将厨余垃圾转化为虫沙有机肥,处理过程是一种有机固体废弃物的资源化新方法.为评估黑水虻处理厨余垃圾的效率与安全性,本课题研究黑水虻在厨余垃圾处理过程中,对大肠杆菌O157:H7(EC)、鼠伤寒沙门氏菌(ST)及金黄色葡萄球(SA)的灭活能力,评价黑水虻体内的抑菌因子,分析3种病原菌对黑水虻生长增重及厨余转化效率的影响.经过18 d的黑水虻处理,研究发现:①第0和第6 d两次以6.4~7.1 log10 CFU·g-1的浓度向厨余垃圾中分别接种EC、ST和SA以后,EC经4~6 d处理被全部灭活、ST经3~4 d处理被全部灭活,SA经6 d处理,浓度下降到1.9~2.6 log10 CFU·g-1,但不能被全部灭活,病原菌的灭活效率呈现EC=ST>SA的趋势(p < 0.001),且黑水虻体内无EC、ST或SA残留;②厨余垃圾降解过程中,初期和中期pH值主要呈现酸性(4.0~5.3),对抑制EC、ST和SA起到了促进作用,后期pH值呈中性至弱碱性;③黑水虻对于EC和ST能够产生自身免疫抑制因子,且抑制活性ST>EC,但对SA无明显的免疫抑制能力,SA的灭活主要依赖于黑水虻肠道菌群的竞争性抑制作用;④黑水虻的体长、体重、预蛹率、产率,以及厨余垃圾的生物转化率和减量化率未受病原菌存在的影响,18 d后EC组、ST组和SA组的预蛹率均达到在80%以上,厨余减量化率分别达到74.0%、79.1%和78.5%,生物转化率分别达到13.0%、13.2%、19.4%.综上,黑水虻能够在彻底灭活EC、ST,99%灭活SA的同时,高效降解厨余垃圾(减量化率>74%),并转化为虫体有机质(虫产率>10%),是一种高效卫生的厨余垃圾资源化方法.今后的研究中,还需要加强以金葡菌为代表的抗逆性病原菌的灭活机制的探讨.  相似文献   
418.
A multinational collaborative study during the summer of 1983 addressed organizational alternatives in natural systems management. Participants were particularly interested in ways different governments attempted to resolve the disparity between the interconnected quality of nature and the compartmentalized structure of bureaucracies. Five patterns of organization have evolved to meet this challenge: mission agencies managing ecosystems; independent or interagency central environmental units: environmental units within mission agencies; environmental components within central planning units; and regional superagencies. The systems developed by five nations—the United States, Korea, Malaysia, the Philippines, and Thailand—are analyzed and compared in terms of these five patterns.  相似文献   
419.
LEONARD ORTOLANO has written a textbook, Environmental Planning and Decision Making, that is ideal for introducing undergraduates to the field of environmental planning. His three chapters on environmental impact assessment (from 16 chapters overall) present a range of impact assessment methods in a helpful decision-making context. Specific techniques for considering biological factors in planning, evaluating the visual qualities of the environment, assessing noise impacts, assessing air quality impacts, and assessing impacts on water resources are also covered in five additional chapters. Professional planners and engineers should find this introduction to the approaches employed by specialists of various kinds helpful. With the permission of the publisher, John Wiley and Sons, we here reprint Chapter 15, “Estimating Air Quality Impacts,” from Ortolano's excellent book. This straightforward presentation of a six-step process for establishing the air quality impacts of proposed development projects is a model of clarity.  相似文献   
420.
湿地土壤有机碳及其活性组分分布特征影响因素研究   总被引:1,自引:0,他引:1  
红碱淖湖泊湿地是西北半干旱荒漠区重要的生态屏障,随着湖泊面积的减少以及土壤退化程度的加剧,逐渐形成5种典型的景观类型(盐碱沼泽、沼泽化草甸、草地、草原化沙地、沙地)。基于野外实地调查,选取红碱淖湖泊湿地流域蟒盖兔和尔林兔2个典型子流域,研究湖泊退化后不同景观类型土壤有机碳及其活性组分的分布特征及其影响因素。结果表明,5种景观类型土壤有机碳(SOC)、土壤可溶性有机碳(DOC)、土壤易氧化态有机碳(EOC)含量均较低。土壤SOC和EOC在垂直剖面上分布特征一致,土壤EOC与土壤有机质动态变化密切相关,土壤砂砾含量高是研究区土壤有机碳含量较低的主要原因。  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