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   1981篇
  免费   120篇
  国内免费   459篇
安全科学   141篇
废物处理   78篇
环保管理   157篇
综合类   965篇
基础理论   399篇
污染及防治   527篇
评价与监测   130篇
社会与环境   111篇
灾害及防治   52篇
  2024年   5篇
  2023年   39篇
  2022年   94篇
  2021年   88篇
  2020年   72篇
  2019年   70篇
  2018年   82篇
  2017年   93篇
  2016年   101篇
  2015年   115篇
  2014年   125篇
  2013年   187篇
  2012年   204篇
  2011年   197篇
  2010年   174篇
  2009年   164篇
  2008年   165篇
  2007年   158篇
  2006年   150篇
  2005年   72篇
  2004年   44篇
  2003年   28篇
  2002年   34篇
  2001年   19篇
  2000年   18篇
  1999年   11篇
  1998年   7篇
  1997年   11篇
  1996年   3篇
  1995年   8篇
  1994年   3篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1966年   1篇
  1964年   1篇
排序方式: 共有2560条查询结果,搜索用时 31 毫秒
191.
浅谈环境监测社会化的质量监管新思路   总被引:1,自引:0,他引:1  
分析了现阶段社会环境检测市场的发展现状及存在的问题,探讨了从环境检测上岗能力、专业技能再教育、从业履历和信用等方面对社会环境检测从业人员进行管理的必要性,提出在机构环境监测能力、检测人员结构流动性、仪器设备在用状态和更新频率、从事环境监测业务信用等方面建立评估机制,推动环境监测市场健康发展。  相似文献   
192.
Metal contents (Al, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Ti, and Zn) have been measured in 30 surface soils on Fildes Peninsula, King George Island, Antarctica, yielding values (in milligrams kilogram(-1)) of 41.57-80.65 (Zn), 2.76-60.52 (Pb), 0.04-0.34 (Cd), 7.18-25.03 (Ni), 43,255-70,534 (Fe), 449-1,401 (Mn), 17.10-64.90 (Cr), 1,440-25,684 (Mg), 10,941-49,354 (Ca), 51.10-176.50 (Cu), 4,388-12,707 (Ti), 28,038-83,849 (Al), and for Hg (in nanograms gram(-1)) 0.01-0.06. Relative cumulative frequency analysis was used to determine the baseline values for the 13 metals. Compared with adjacent areas in Antarctica, Mg and Ni are significantly lower, but Cu is significantly higher than that of McMurdo Station. Enrichment factor analysis and the geo-accumulation index method were applied in order to determine the extent of anthropogenic contamination, and both show that Pb, Cd, and Hg have been significantly increased by human activities. Principal component analysis was used to identify the sources of metals in these soil samples.  相似文献   
193.
In 1998, the Agrio and Guadiamar rivers underwent an enormous environmental disaster caused by the rupture of the Aznalcóllar tailings dam and the release of 6 hm3 of pyrite sludge and acidic water. Both rivers run over recent alluvial materials which form a small-sized aquifer which is however important because underground water feeds the flow of the rivers. This work analyzes the state of groundwater 10 years after the spill. Before the dam failure, this aquifer was already contaminated in the zone nearest to the mine, to which the impact of the spill was added. Contamination levels in the alluvial aquifer of the Agrio River have decreased remarkably. However, they are still important, with acidic pH values and high concentrations of toxic elements (maximum values of 16 mg/L of Zn and 15 mg/L of Al). There are also important levels of contamination in the Guadiamar alluvial area closest to the mine, as well as in specific zones located further south. The concentration of toxic elements is mainly controlled by pH. The evolution of contaminant levels show a sharp decrease after the first years following the spill, followed by a subsequent stabilization. It is necessary to take measures for the recovery of the aquifer because, otherwise, groundwater will continue contributing contaminants into the Agrio and Guadiamar rivers.  相似文献   
194.
The management of protected areas in karstic regions is a challenge because flooded cave systems form there and provide underground hydrological conducts that may link different zones. As a consequence, affectations to the protected areas can possibly occur as a consequence of human activities in remote areas and may therefore pass undetected. Thus, the monitoring of possible contaminants in these regions is becoming imperative. In this work, we analyze the concentration of essential (iron) and non-essential metals (cadmium and chromium) in the seagrass Thalassia testudinum that grows in Yalahau Lagoon, located in a near-to-pristine protected area of the Yucatán Peninsula, close to the rapidly developing touristic belt of the Mexican Caribbean. Salinity and silicate patterns show that Yalahau is an evaporation lagoon, where groundwater discharge is important. High iron (>400 μg/g), cadmium (>4 μg/g), and chromium (≈1 μg/g) concentrations were found in the area of highest groundwater input of the lagoon. High levels (5.1 μg/g) were also found near the town dump. In the rest of the sampling sites, metal concentrations remained near to background levels as estimated from other works. Temporal changes of concentrations in the seagrass tissues show also a local input and an input from the groundwater that could provoke an environmental problem in the Yalahau Lagoon in the near future.  相似文献   
195.
196.
为研究长三角典型城市公交车细颗粒物排放特征,采用便携式排放测试系统(PEMS),对上海、杭州和苏州三大城市的8辆典型城市公交车开展实际道路细颗粒物排放实验。研究结果表明:长三角典型城市车辆的实际道路平均车速为22.7 km/h,怠速比例为20.4%,加减速比例为54.5%;在稳态行驶工况下,随车速增大,公交车颗粒物质量及数量排放呈逐渐增大趋势;在20 km/h车速范围内,上海国III、国IV和苏州国III公交车颗粒数浓度呈双峰粒径分布,其他公交车均为单峰分布;随比功率的增大,公交车颗粒质量呈逐渐增大的趋势,国IV公交车颗粒数量呈先下降再增大趋势,国III公交车颗粒数量呈上升趋势;公交车颗粒质量综合排放因子为0.8~189 mg/km,颗粒数量综合排放因子为6.2×1012~9.6×1014#/km。  相似文献   
197.
针对目前交界断面水质监测与空气自动监测站质量管理工作中存在的质控难点,介绍了江苏省的解决办法。通过统一技术细节、联合监测及强化监测人员持证上岗自认定考核等手段,解决了交界断面水质监测技术纠纷;通过设立省级质管站、进行可信度评估等措施,强化空气自动监测站的质量管理。  相似文献   
198.
This study develops a depth-averaged two-dimensional (2D) numerical model using a finite difference method (FDM) on a staggered grid. The governing equations were solved using the Marker and Cell method that was developed at the Los Alamos laboratories by Harlow and Welch in 1965. In the paper, an explicit FDM was used to solve the governing equations. A first-order approximation was used for the temporal derivative. Second-order central difference approximations were used for space discretization. The time step is limited by the Courant–Friedrichs–Lewy (CFL) condition. The time step used in this study depends on the grid spacing and velocity components in the x- and y-directions. The study is divided into two steps: the first step is to develop a depth-averaged 2D numerical model to simulate the flow process. The second constructs a module to calculate the bed load transport and simulate the river morphology in the areas that have steep slopes, torrents, and mountain rivers. Developed model was applied to the artificial channel and a flood event in the Asungjun River section of the mountainous Yangyang Namdae River (South Korea). General simulation results showed that the developed model was in good agreement with the observed data.  相似文献   
199.
G C/MS法测定环境空气中痕量POPs类有机氯农药及降解产物   总被引:4,自引:0,他引:4  
采用快速溶剂萃取-氟罗里硅土柱净化-气相色谱/质谱联用法测定环境空气中POPs类有机氯农药及其降解产物.艾氏剂、狄氏剂、异狄氏剂、六六六、滴滴涕,七氯、氯丹、灭蚁灵及其降解产物的检出限为2.0 ng~4.6 ng,空白加标回收率为62.1%~118%,RSD为6.8%~15.2%.  相似文献   
200.
Many bird populations have recently changed their migratory behavior in response to alterations of the environment. We collected data over 16 years on male Great Bustards (Otis tarda), a species showing a partial migratory pattern (sedentary and migratory birds coexisting in the same breeding groups). We conducted population counts and radio tracked 180 individuals to examine differences in survival rates between migratory and sedentary individuals and evaluate possible effects of these differences on the migratory pattern of the population. Overall, 65% of individuals migrated and 35% did not. The average distance between breeding and postbreeding areas of migrant individuals was 89.9 km, and the longest average movement of sedentary males was 3.8 km. Breeding group and migration distance had no effect on survival. However, mortality of migrants was 2.4 to 3.5 times higher than mortality of sedentary birds. For marked males, collision with power lines was the main cause of death from unnatural causes (37.6% of all deaths), and migratory birds died in collisions with power lines more frequently than sedentary birds (21.3% vs 6.3%). The percentage of sedentary individuals increased from 17% in 1997 to 45% in 2012. These results were consistent with data collected from radio‐tracked individuals: The proportion of migratory individuals decreased from 86% in 1997–1999 to 44% in 2006–2010. The observed decrease in the migratory tendency was not related to climatic changes (temperatures did not change over the study period) or improvements in habitat quality (dry cereal farmland area decreased in the main study area). Our findings suggest that human‐induced mortality during migration may be an important factor shaping the migration patterns of species inhabiting humanized landscapes.  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