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   379篇
  免费   1篇
  国内免费   7篇
安全科学   18篇
废物处理   25篇
环保管理   30篇
综合类   42篇
基础理论   69篇
环境理论   1篇
污染及防治   132篇
评价与监测   46篇
社会与环境   23篇
灾害及防治   1篇
  2023年   17篇
  2022年   34篇
  2021年   25篇
  2020年   7篇
  2019年   6篇
  2018年   11篇
  2017年   11篇
  2016年   10篇
  2015年   4篇
  2014年   23篇
  2013年   47篇
  2012年   17篇
  2011年   28篇
  2010年   9篇
  2009年   14篇
  2008年   14篇
  2007年   19篇
  2006年   7篇
  2005年   14篇
  2004年   11篇
  2003年   11篇
  2002年   4篇
  2001年   4篇
  2000年   4篇
  1999年   1篇
  1997年   1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
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1979年   3篇
  1975年   1篇
  1965年   2篇
  1964年   1篇
  1963年   3篇
  1962年   1篇
  1961年   1篇
  1959年   1篇
  1958年   1篇
  1956年   1篇
  1955年   3篇
  1929年   1篇
排序方式: 共有387条查询结果,搜索用时 218 毫秒
1.
2.
3.
Life cycle energy impacts of automotive liftgate inner   总被引:1,自引:0,他引:1  
This paper compares the life cycle energy use of a cast-aluminum, rear liftgate inner and a conventional, stamped steel liftgate inner used in a minivan. Using the best available aggregate life cycle inventory data and a simple spreadsheet-level analysis, energy comparisons were made at both the single-vehicle and vehicle-fleet levels. Since the product manufacture and use are distributed over long periods of time that, in a fleet, are not simple linear combinations of single product life cycles. Thus, it is all the products in use over a period of time, rather than a single product, that are more appropriate for the life cycle analysis. Using a set of consistent data, analyses also examine sensitivity to the level of analysis and the assumptions to determine the most favorable materials with respect to life cycle energy benefits.As expected, life cycle energy impacts of aluminum are lower than steel at a single-vehicle level – energy savings are determined to be 1.8 GJ/vehicle. Most energy savings occur at the vehicle operation phase due to improved fuel economy from lightweighting. The energy benefits are realized only very close to the average vehicle life of 14 years. With the incremental growth of the vehicle fleet, it takes longer – about 21 years – for aluminum to achieve life cycle equivalence with steel. The number of years aluminum needs to achieve equivalence with steel was found to be quite sensitive to aluminum manufacturing energy and fuel economy. As the steel industry races to compete with other materials for automotive lightweighting, a systems approach, instead of part-to-part comparison, is more appropriate in the determination of viability of aluminum substitution from an energy perspective.  相似文献   
4.
The Barind tract of West Bengal is an area of tropical sub-humid region composed of old alluvial soil. The area has high water demand due to growing population pressure and intensification in agricultural activity. These create huge stress on surface and ground water availability. Continuous withdrawal of ground water has become an alternative source of irrigation water which has also again made the condition critical. Ground water level has been lowered down drastically in many parts in this region. Under this circumstance, it is necessary to delineate potential ground water-bearing layers. Therefore, the present study attempts to identify potential ground water-bearing zones to manage ground water effectively. Instead of usually used parameters for ground water potentiality delineation here only some particular litholog parameters like breadth of water-bearing layer, depth of water-bearing layer, presence of clay layer above or below major water-bearing layer have been considered for delimiting the same. The result shows that out of total area, 60% area (405,382.2 ha) falls under very low to low potential ground water-bearing zone and only 8.19% area (55,634.97 ha) is potential. Considering this spatial pattern of ground water availability, harvesting structure and magnitude of water withdrawing should be designed.  相似文献   
5.
Environmental Science and Pollution Research - To investigate the complex Pb-Cd exposure network in school-going children, a thorough investigation of the probable exposure means (diet, water, and...  相似文献   
6.

This study is trying to explore the relationship between corporate social responsibility (CSR) disclosures and financial performances (FP) through mediating role of the employee productivity (EP). This study classifies the CSR performances into four contexts, for instance, environment social governance (ESG), environmental improvement activity scores of CSR, social welfare activity score, and governance structure improvement score. The banking performance is classified into three different aspects such as returns on assets (ROA), returns on equity (ROE), and nominal interest margin profit (NIMP). The study covers the data set start from 2008 to 2019 regarding thirty commercial banks of China. The study uses the linear, non-linear, and quadratic techniques to explore the association between CSR disclosures and banking performances. The linear model result shows that the governance score is significant influencing the banking performance. Moreover, the employee productivities are also positive significant affecting the baking performances. The non-linear results of model show that composite score of ESG with employee productivity has significant influence on financial performance.

  相似文献   
7.
Environmental Science and Pollution Research - There has been alarming depletion of manganese (Mn) reserves owing to the ongoing extensive mining operations for catering the massive industrial...  相似文献   
8.
Environmental Science and Pollution Research - The need for sustainable production of renewable biofuel has been a global concern in the recent times. Overcoming the tailbacks of the first- and...  相似文献   
9.
TiO2 immobilized on SiO2 (TiO2/SiO2) have been prepared by sol-gel method and various ions of transition metals (Cr3+, Co2+, Ni2+, Cu2+, and Zn2+) were doped on the photocatalyst using wet impregnation method under reducing calcination atmosphere. The photocatalytic activity of metal doped TiO2/SiO2 towards phenol degradation under black light irradiation were investigated and compared with undoped TiO2/SiO2. The results showed that the photoresponse of Cu2+ and Zn2+ doped TiO2/SiO2 were larger than undoped TiO2/SiO2, indicating that the photogenerated carriers were separated more efficiently in Cu2+ and Zn2+ doped TiO2/SiO2. The reactivity was in the order of Cu2+ > Zn2+ > Ni2+ > Cr3+ > Co2+. The different photoreactivity was ascribed to combine effect of the different ionic radii and photocorrison tendency of the dopants. The sample was also characterized by surface analytical methods such as X-ray diffraction, scanning electron micrograph/electron dispersive X-ray analyzer and UV-Vis absorption spectrum.  相似文献   
10.
Tool life has been a vital issue in machining titanium alloys. Recently, an atomization-based cutting fluid (ACF) application has been found to be an effective approach for cooling and lubrication in micromachining operations. In this study, an ACF spray system is developed for macro-scale turning of Ti–6Al–4V. The spray system is designed to minimize interaction between the fluid droplets, and the gas nozzle to control the divergence of the fluid droplets. Experiments are conducted to study the effect of five specific ACF spray parameters including fluid flow rate, spray distance, impingement angle, and type and pressure level of the droplet carrier gas on cutting forces, tool life, and chip characteristics. It has been observed that the combination of lower pressure (150 psi) air-mixed CO2 with a higher flow rate (20 ml/min) and a larger spray distance (35 mm) produces a significantly longer tool life and broken chips. The results also reveal that the ACF spray system can extend tool life up to 40–50% over flood cooling.  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