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   971篇
  免费   64篇
  国内免费   309篇
安全科学   79篇
废物处理   56篇
环保管理   71篇
综合类   523篇
基础理论   213篇
污染及防治   275篇
评价与监测   39篇
社会与环境   39篇
灾害及防治   49篇
  2023年   20篇
  2022年   60篇
  2021年   40篇
  2020年   35篇
  2019年   39篇
  2018年   36篇
  2017年   44篇
  2016年   45篇
  2015年   46篇
  2014年   70篇
  2013年   87篇
  2012年   78篇
  2011年   69篇
  2010年   61篇
  2009年   64篇
  2008年   48篇
  2007年   54篇
  2006年   37篇
  2005年   36篇
  2004年   32篇
  2003年   33篇
  2002年   39篇
  2001年   24篇
  2000年   34篇
  1999年   41篇
  1998年   43篇
  1997年   24篇
  1996年   18篇
  1995年   21篇
  1994年   16篇
  1993年   6篇
  1992年   10篇
  1991年   9篇
  1990年   6篇
  1988年   2篇
  1987年   1篇
  1986年   4篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1981年   3篇
  1977年   2篇
  1969年   1篇
排序方式: 共有1344条查询结果,搜索用时 327 毫秒
101.
对乌鲁木齐市燃煤点派数量、耗煤量、污染物的排放量以及在各功能区的分布分别进行了统计分析,对污染物的排放量在不同高度空间的分布也进行了统计分析,从而得出了确切的结论并提出了相应的建议。  相似文献   
102.
The Klang River Basin is located in the most densely populated region in Malaysia, with its heavy concentration of industries and population. A systematic study of the pollution to this river system caused by phenolic compounds have been carried out under this project. Analyses of water samples from the Klang River by high performance liquid chromatography (HPLC) with an ultraviolet (UV) detector at 280 nm have shown the presence of some priority phenolic pollutants.  相似文献   
103.
Uptake, accumulation and translocation of caffeine by Scirpus validus grown in hydroponic condition were investigated. The plants were cultivated in Hoagland’s nutrient solution spiked with caffeine at concentrations of 0.5–2.0 mg L?1. The effect of photodegradation on caffeine elimination was determined in dark controls and proved to be negligible. Removal of caffeine in mesocosms without plants showed however that biodegradation could account for about 15–19% of the caffeine lost from solutions after 3 and 7 d. Plant uptake played a significant role in caffeine elimination. Caffeine was detected in both roots and shoots of S. validus. Root concentrations of caffeine were 0.1–6.1 μg g?1, while the concentrations for shoots were 6.4–13.7 μg g?1. A significant (p < 0.05) positive correlation between the concentration in the root and the initial concentrations in the nutrient solution was observed. The bioaccumulation factors (BAFs) of caffeine for roots ranged from 0.2 to 3.1, while BAFs for shoots ranged from 3.2 to 16.9. Translocation from roots to shoots was the major pathway of shoot accumulation. The fraction of caffeine in the roots as a percentage of the total caffeine mass in solution was limited to 0.2–4.4% throughout the whole experiment, while shoot uptake percentage ranged from 12% to 25% for caffeine at the initial concentration of 2.0 mg L?1 to 50–62% for caffeine at the initial concentration of 0.5 mg L?1. However, a marked decrease in the concentration of caffeine in the shoots between d-14 and d-21 suggests that caffeine may have been catabolized in the plant tissues subsequent to plant uptake and translocation.  相似文献   
104.
105.
生物通风技术修复柴油污染土壤的土柱模拟实验   总被引:1,自引:0,他引:1  
生物通风技术是将土壤气相抽提和生物降解结合起来的原位强迫氧化降解方法,对于修复因地下储油罐泄漏引起的土壤污染具有广阔的应用前景。通过室内土柱模拟柴油泄漏污染土壤,分析了不同历时残余总石油烃(total pe-troleum hydrocarbon,TPH)的平衡分布规律以及土壤中不同深度柴油量、总柴油量的变化。结果表明:(1)各柱残余TPH剖面分布差异的原因受土柱的初始装填情况的影响较大;(2)残余TPH平衡分布曲线呈双峰型的土柱,柴油的去除主要以挥发作用及生物降解作用为主;(3)挥发作用主要是由通风孔隙体积数及土壤含水率来影响的;重力作用则主要是由初始油浓度、土壤含水率、C∶N∶P影响的;除通风方式外,其余4个因素都对生物降解作用有影响;(4)初始油浓度较大,土壤含水率较小的柱8和柱11,生物降解作用最明显,柴油去除效果最好。该成果可为生物通风过程的强化提供理论依据。  相似文献   
106.
长江沉积物中痕量氯代酚类化合物的测定   总被引:10,自引:0,他引:10  
本文利用同位素稀释质谱法对长江南京段沉积物中18种氯代酚进行了分离鉴定,结果表明,沉积物中CPs的含量以五氯苯酚为主,  相似文献   
107.
阐述了南亚热带低山、丘陵、台地赤红壤总库容、贮水库容、通透库容的占有情况。探讨了水库容的有效性以及不同利用方式的赤红壤有效水库容与无效水库容的差异,并对影响赤红壤水分有效性的因素作了分析.结果表明:赤红壤贮水库容小,尤其是有效水库容小;赤红壤水分有效性主要与土壤有机质相关。  相似文献   
108.
依据田间实测资料,在分析丘陵赤红壤水分性质的基础上,建立了土壤有效含水量与土壤物理粘粒含量之间的数学模型、土壤水分特征曲线数学模型、土壤月均贮水量与月降雨总量之间的数学模型和径流率与土壤表层初始含水量之间的数学模型,研究了土壤水分循环与平衡数学模型及各分量与参数的确定方法.  相似文献   
109.
110.
Duan J  Bi X  Tan J  Sheng G  Fu J 《Chemosphere》2007,67(3):614-622
Size distribution aerosol samples were collected at an urban location of Guangzhou in four seasons of 2003-2004 by a MOUDI (Micro-orifice Uniform Deposit Impactor). The particle loading (PM10: 80-397 microg m(-3)) was comparable with some other Asia cities; however, much higher than that of Western Europe and North America. Polycyclic aromatic hydrocarbons (PAHs) were measured by gas chromatography with mass selective detector (GC-MS). Seasonal effects on the size distribution of PAHs are presented. Bimode (accumulation and coarse mode) and unimode (accumulation mode) distributions were observed for low-molecule-weight and high-molecule-weight PAHs. A slight shift to larger particles was found for the accumulation mode in autumn and winter, compared with that of spring and summer. One explanation is that the longer aging process of PAHs in autumn and winter would result in volatilization from finer particles followed by condensation onto coarser particles. Another is there was mixing process of local emission with long-range transported aerosol in autumn and winter. The relative higher value of IcdP/(BghiP+IcdP) and lower value of BghiP/BeP in winter also give evidences to the mixing process. The level of PAHs concentration has been much elevated in recent years. This can be attributed to the fast growth of motor vehicle and energy consumption.  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