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   7331篇
  免费   679篇
  国内免费   1046篇
安全科学   825篇
废物处理   138篇
环保管理   889篇
综合类   3735篇
基础理论   564篇
污染及防治   537篇
评价与监测   2095篇
社会与环境   148篇
灾害及防治   125篇
  2024年   38篇
  2023年   148篇
  2022年   235篇
  2021年   244篇
  2020年   314篇
  2019年   228篇
  2018年   236篇
  2017年   296篇
  2016年   352篇
  2015年   397篇
  2014年   435篇
  2013年   504篇
  2012年   512篇
  2011年   538篇
  2010年   371篇
  2009年   385篇
  2008年   307篇
  2007年   427篇
  2006年   454篇
  2005年   387篇
  2004年   302篇
  2003年   409篇
  2002年   272篇
  2001年   257篇
  2000年   221篇
  1999年   157篇
  1998年   101篇
  1997年   117篇
  1996年   93篇
  1995年   64篇
  1994年   56篇
  1993年   45篇
  1992年   26篇
  1991年   24篇
  1990年   27篇
  1989年   16篇
  1988年   10篇
  1987年   13篇
  1986年   5篇
  1985年   4篇
  1984年   4篇
  1983年   2篇
  1982年   3篇
  1981年   3篇
  1980年   6篇
  1979年   3篇
  1978年   2篇
  1973年   2篇
  1972年   2篇
  1971年   1篇
排序方式: 共有9056条查询结果,搜索用时 15 毫秒
11.
废水中糠醛测定方法的探讨   总被引:2,自引:0,他引:2  
介绍了废水中糠醛的测定方法,该法测定简单,重现性好,相对标准偏差为5.7%,最低检出限为0.01mg/L。  相似文献   
12.
Ozone concentrations were measured in Zagreb at four sites from May 1999 to April 2001 in order to categorize the air quality with respect to ozone. In the summer of 2000, the ozone measurements were also extended to four sites in the suburbs of Zagreb. Methods of active and passive sampling with nitrite ion as a reagent were used. In the northern part of the town ozone was analyzed by an automatic device. Automatic device measurements in the years 1999 and 2000 showed that hourly averages of ozone concentrations did not exceed the Croatian recommended value of the 98th percentile (180 g m–3). Over the two-year period, 24-h averages occasionally exceed 110 g m–3 in city center and in the northern part of the town. Regardless of these isolated examples, ozone was well within acceptable concentrations. Ozone concentrations measured in summer 2000 were higher in the suburbs of Zagreb than in the city. The 98th percentile values higher than 110 g m–3 were recorded at three sites.  相似文献   
13.
The Impact of Landsat Satellite Monitoring on Conservation Biology   总被引:1,自引:0,他引:1  
Landsat 7s recent malfunctioning will result in significant gaps in long-term satellite monitoring of Earth, affecting not only the research of the Earth science community but also conservation users of these data. To determine whether or how important Landsat monitoring is for conservation and natural resource management, we reviewed the Landsat programs history with special emphasis on the development of user groups. We also conducted a bibliographic search to determine the extent to which conservation research has been based on Landsat data. Conservation biologists were not an early user group of Landsat data because a) biologists lacked technical capacity – computers and software – to analyze these data; b) Landsats 1980s commercialization rendered images too costly for biologists budgets; and c) the broad-scale disciplines of conservation biology and landscape ecology did not develop until the mid-to-late 1980s. All these conditions had changed by the 1990s and Landsat imagery became an important tool for conservation biology. Satellite monitoring and Landsat continuity are mandated by the Land Remote Sensing Act of 1992. This legislation leaves open commercial options. However, past experiments with commercial operations were neither viable nor economical, and severely reduced the quality of monitoring, archiving and data access for academia and the public. Future satellite monitoring programs are essential for conservation and natural resource management, must provide continuity with Landsat, and should be government operated.  相似文献   
14.
Catalytic wet air oxidation (CWAO) is one of the most promising technologies for pollution abatement. Developing catalysts with high activity and stability is crucial for the application of the CWAO process. The Mn/Ce complex oxide catalysts for CWAO of high concentration phenol-containing wastewater were prepared by coprecipitation. The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis. The Mn/Ce serial catalysts were characterized by Brunauer-Emmett-Teller (BET) analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry (ICP-AES). The results show that the catalysts have high catalytic activities even at a low temperature (80°C) and low oxygen partial pressure (0.5 MPa) in a batch reactor. The metallic ion leaching is comparatively low (Mn<6.577 mg/L and Ce<0.6910 mg/L, respectively) in the CWAO process. The phenol, CODCr, and TOC removal efficiencies in the solution exceed 98.5% using the optimal catalyst (named CSP). The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater. Translated from Techniques and Equipment for Environmental Pollution Control, 2005, 6(2): 40–44 [译自: 环境污染治理技术与设备]  相似文献   
15.
本文简述了室内有害气体氨气污染对人类健康的危害 ,详细介绍了日前国内外测量室内空气中氨含量所应用的不同方法 ,研究讨论了各种方法的最低检测浓度 ,在具体检测中各种不同方法的干扰离子以及干扰离子所允许的最高浓度 ,比较各种不同方法的优劣  相似文献   
16.
以监测预报工作为导向推进数字化监测教学   总被引:1,自引:1,他引:1  
地震预测的发展方向,是从协同的观点,多层面地统筹考虑地震监测体系的建设,实现基础研究与实际地震预测工作的结合.本文从如何利用原有监测资料、连续前兆监测数据处理系统的建立、前兆监测体系数据报送体系等地震监测工作环节,分析地震监测教学如何与监测工作方向相一致,并对教学改革如何结合台站技术人员更新提出了几点看法.  相似文献   
17.
SO2 和氟化物对农作物的危害可通过症状、镜检和受害叶片的化学分析来鉴别 ,并从风向、与污染源距离、障碍物和叶片成熟程度几方面与作物病虫等影响因素相区别。排放浓度、接触时和作物本身抗性是影响危害程度的主要因素。应从治理污染、选种抗性强树木、避开作物敏感生育期、合理种植、加强施肥等方面采取措施加以防治  相似文献   
18.
窑尾监测SO_2时,有时会出现其浓度低于仪器最低检出限的情况,应根据窖尾类型、煤中硫含量大小,有无脱硫工艺等情况,认真对比、计算分析,以保证监测数据真实可靠。  相似文献   
19.
根据大量模式化参数,通过核算,得出了阜新市城区普通空气污染物的环境容量,给出了城区各分区及每个网格的分解量,应用这些成果,将对老污染源及新工业项目的环境管理,发挥极其重要的作用,对阜新市的可持续发展战略有着重要意义。  相似文献   
20.
共振腔消声器在煤矿风井噪声治理中的应用   总被引:1,自引:0,他引:1  
对煤矿风井噪声产生的机理与特性进行了分析,提出了用共振腔消声器治理风井噪声的新方法,详细阐述了该方法所依据的理论基础,并以应用实例加以说明。  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