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   387篇
  免费   1篇
  国内免费   10篇
安全科学   18篇
废物处理   29篇
环保管理   26篇
综合类   41篇
基础理论   78篇
环境理论   1篇
污染及防治   132篇
评价与监测   51篇
社会与环境   21篇
灾害及防治   1篇
  2023年   18篇
  2022年   40篇
  2021年   25篇
  2020年   7篇
  2019年   6篇
  2018年   13篇
  2017年   12篇
  2016年   14篇
  2015年   4篇
  2014年   21篇
  2013年   51篇
  2012年   14篇
  2011年   20篇
  2010年   13篇
  2009年   15篇
  2008年   15篇
  2007年   16篇
  2006年   9篇
  2005年   15篇
  2004年   11篇
  2003年   8篇
  2002年   4篇
  2001年   5篇
  2000年   5篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1979年   3篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1965年   2篇
  1964年   1篇
  1963年   3篇
  1962年   1篇
  1961年   2篇
  1959年   1篇
  1958年   2篇
  1957年   1篇
  1955年   2篇
  1929年   1篇
排序方式: 共有398条查询结果,搜索用时 31 毫秒
101.
The first step in assessing the risk of water contamination by Cryptosporidium parvum oocysts from feedlot cattle (Bos taurus) production systems is to quantify the number of C. parvum oocysts present in the fecal material deposited by feedlot cattle. Our primary objective for this project was to estimate the daily environmental load of C. parvum oocysts in fecal material deposited by feedlot cattle from across the central and western USA. Our secondary goal was to genotype isolates of C. parvum from feedlot cattle to help facilitate proper identification of mammalian sources of waterborne C. parvum. Based on 5274 fecal samples from 22 feedlots in seven states (California, Washington, Colorado, Oklahoma, Texas, Nebraska, and South Dakota), we estimated a point prevalence of C. parvum of 0.99 to 1.08% in fecal material from feedlot pens from a wide range of climates and a diverse range of feedlot management systems. On average, fresh fecal material from throughout feedlot systems (recent arrivals to nearing slaughter) contained about 1.3 to 3.6 oocysts/g feces, which roughly translates to about 2.8 x 10(4) to 1.4 x 10(5) oocysts/animal per day.  相似文献   
102.
Environment, Development and Sustainability - The present study evaluated the effectiveness of stocking the Gangetic carps, viz. Labeo catla, Labeo rohita, and Cirrhinus mrigala, in a large...  相似文献   
103.
Environmental Science and Pollution Research - Delhi has been identified as one of the highly polluted cities in the world and recently associated with the highest population weighted PM2.5...  相似文献   
104.
Environmental Science and Pollution Research - Solid waste management of the potato peels, generated during the processing of potatoes, can be done sustainably by adding value to the peel waste....  相似文献   
105.
Alarming environmental pollution from petroleum based non-biodegradable disposable packaging films has generated concern for development of alternatives from natural polymers such as starch. In the present work, the biodegradability of a self-supporting film made from starch and polyvinyl alcohol (PVA) (starch:PVA?=?9:1 as the polymer) together with glutaraldehyde as crosslinker and sodium propionate (SP) as antimicrobial was investigated by soil burial method. The changes in soil composition namely pH, organic carbon, available and total nitrogen, and water holding capacity as a result of biodegradation were also estimated. The film underwent ≈?90% biodegradation within a period of 28 days, with simultaneous increase in soil nutrients. Moreover, the pH remained in the accepted limit for plant growth. Thus, antimicrobial in the film did not hamper its biodegradation, rather disposal of the film in soil might facilitate plant growth.  相似文献   
106.
ABSTRACT

Estimation of State of Health (SoH) of Lithium-ion (Li-ion) battery is essential to predict the lifespan of batteries of an electric vehicle (EV). The efficient prediction of battery health indicates to the effective and safe operation of EV. However, delivering an effective and accurate method for the estimation of SoH in the real condition is truly a challenging task. The present study proposed a holistic procedure of combining both experimental and numerical investigations to conduct the fundamental study on coupled mechanical-electrochemical behavior of Li-ion battery. The proposed investigation highlighted the effect of stress on the capacity of the battery, considering capacity fade as an equivalent parameter to its health for real-time estimation of SoH. Finally, a simple model of Artificial Neural Network (ANN) is provided, which shows the linear dependency of stress with the SoH. The results obtained from the ANN model are validated with a Linear Regression (LR) model for a better understanding of the inspection. The predicted value of mean Square Error (MSE) and R square error in the ANN training model are found to be 0.000309 and 0.849687, respectively. Whereas for the test model, these predicted values are found to be 0.000438 and 0.819347, respectively.  相似文献   
107.
An experiment was conducted under laboratory conditions to investigate the effect of two systemic herbicides, viz. pendimethalin (a dinitroaniline) and quizalofop (an arylphenoxy propionic acid) at their recommended field application rates (1.0?kg and 50?g active ingredient per hectare, respectively), either separately or in a combination, on growth and activities of phosphate-solubilizing microorganisms in relation to their effects on biochemical transformations and availability of organic carbon, total and available phosphorus in a Typic Haplustept soil of West Bengal, India. Application of herbicides, in general, significantly stimulated the growth and activities of phosphate-solubilizing microorganisms which increased microbial biomass resulting in higher accumulation of oxidizable organic carbon, total and available phosphorus in soil as compared to untreated control. The combined application of both the herbicides highly stimulated the proliferations of phosphate-solubilizing microorganisms, while pendimethalin alone significantly accentuated phosphate-solubilizing capacities 36.4% as compared to untreated control and retained highest amount of total phosphorus due to greater microbial activities in soil. The separate application of quizalofop also manifested an induced effect on the proliferations of phosphate-solubilizing microorganisms and accounted significant amounts of organic carbon and available phosphorus in the soil system. The results of the present study thus indicated that the cited herbicides at their field application rates can be safely used to eradicate weeds in the crop fields.  相似文献   
108.
This study was carried out in three different cities of western Madhya Pradesh (India) to investigate the effects of long-term irrigation with industrial waste water (IWW), contaminated groundwater (CGW), and untreated municipal sewage water (USW) on soil fertility as well as on wheat crop yield. Irrigation with these three types of polluted water increased organic matter content as well as contents of available P (with IWW and USW only), available K, available S, available Zn, available Cu (IWW only), and available Mn (IWW and CGW only). The magnitude of improvement in soil fertility status was the highest in the case of USW, followed by IWW and finally, by CGW. Concentrations of Na in wheat leaf tissue increased by 198 and 58 % whereas concentrations of Ca decreased significantly by 16 and 13 % due to the use of IWW and CGW, respectively, resulting in poor Ca nutrition to the crop. Although wheat grain yield increased considerably due to USW, the same recorded significant decreases with IWW and CGW. In spite of the enhancement in the available nutrient status, decrease in wheat grain yield with the use of IWW and CGW could be due to the build-up of salts in the soil and an imbalance in the Na/Ca ratio in wheat crops irrigated with IWW and CGW. The adverse effect on wheat productivity was more pronounced with IWW as compared to CGW.  相似文献   
109.
110.
This paper presents a comprehensive account regarding concentration, distribution and possible sources of trace elements (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in 20-30 cm sediment cores (<63 microm particle size) collected at the confluence of the Ganges River and Bay of Bengal (Sunderban wetland, India). This work aims to evaluate the fluvio-marine and geochemical processes influencing the metal distribution. The most interesting features are the downward increase of concentrations of majority of the elements reaching overall maximum values at a depth of 10-15 cm observed in station Lot No.8 located along the main stream of the Ganges estuary as well as an overall elevated concentration of all the elements in the lower littoral zone. The interelemental relationship revealed the identical behaviour of elements during its transport in the estuarine environment. The overall variation in concentration can be attributed to differential discharge of effluents originating from industrial and agricultural as well as from domestic sewage. Arsenic exceeded effects range - low (ER - L) concentrations, implying occasional or frequent adverse biological effects. For Cu, Ni and Cr a smaller proportion of samples had exceeded the ER - L values indicating that the dataset would be suitable for future use in evaluating predictive abilities of SQGs.  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