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   10004篇
  免费   1篇
安全科学   58篇
废物处理   779篇
环保管理   1216篇
综合类   971篇
基础理论   3143篇
污染及防治   1874篇
评价与监测   1042篇
社会与环境   921篇
灾害及防治   1篇
  2023年   5篇
  2022年   5篇
  2021年   10篇
  2020年   6篇
  2019年   19篇
  2018年   1485篇
  2017年   1384篇
  2016年   1216篇
  2015年   131篇
  2014年   36篇
  2013年   70篇
  2012年   482篇
  2011年   1357篇
  2010年   696篇
  2009年   602篇
  2008年   886篇
  2007年   1240篇
  2006年   11篇
  2005年   27篇
  2004年   49篇
  2003年   75篇
  2002年   106篇
  2001年   19篇
  2000年   15篇
  1999年   4篇
  1998年   10篇
  1997年   2篇
  1993年   1篇
  1992年   2篇
  1991年   2篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1984年   13篇
  1983年   8篇
  1982年   1篇
  1979年   2篇
  1968年   1篇
  1967年   1篇
  1965年   3篇
  1964年   1篇
  1963年   3篇
  1962年   3篇
  1961年   1篇
  1960年   3篇
  1959年   1篇
  1958年   1篇
  1935年   2篇
  1931年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
We developed an integrated assessment (IA) using models for energy systems analysis and life-cycle assessment (LCA). Based on this assessment framework, we developed cost-benefit analysis (CBA) case studies for a hypothetical project designed to introduce advanced fossil-fired power generation technologies in China. Our MARKAL model for Japan confirmed that radical reductions (i.e., 80 % by 2050) of carbon dioxide (CO2) could be attained from energy systems alone and that credit for emission allowances was required. We evaluated life-cycle costs and emissions of carbon dioxide, sulfur oxide, and nitrogen oxide gases for the energy technologies using an LCA model. Further, we applied a power generation planning model for six Chinese grids to provide a power mix structure, potentially producing credit by installing fossil-fired power generation technology and by using baseline grid emission factors with an average cost of electricity. Finally, by using dynamic emission reductions and additional costs from the two models, we conducted case studies of CBA for a hypothetical project to install the technologies in China. This was accomplished by evaluating emission reductions in monetary terms and by applying a life-cycle impact assessment model. A unique feature of our IA is its dynamic (time-varying) assessment of costs and benefits.  相似文献   
982.
Hurricanes are relatively frequent ecological disturbances that may cause potentially long-term impacts to the coastal environment. Hurricane Katrina hit the Mississippi Gulf Coast in August 2005, and caused a storm surge with the potential to change the trace element content of coastal surface sediments. In this study, surface estuarine and marine sediments were collected monthly following the storm from ten sites along the Mississippi Gulf Coast (Mobile Bay, Grand Bay Bayous Heron and Cumbest, Pascagoula, Ocean Springs, Biloxi Gulf, Back Biloxi Bay, Gulfport Gulf, Gulfport Courthouse Rd, and Gulfport Marina). Concentrations of V, Cr, Mn, Fe, Co, Ni, Zn, As, Cd, and Pb were measured by inductively coupled plasma–mass spectrometry to evaluate their temporal and spatial variations in the year following Hurricane Katrina. Sediments were characterized by pH, particle size distribution and total carbon and nitrogen content. Trace element contents of the sediments were determined in both <2 mm and <63 μm grain size fractions. Results revealed no significant temporal and spatial variability in trace element concentrations, in either size fraction. Potential ecological risk of the sediments was assessed by using NOAA SQuiRTs’ guideline values; most concentrations remained below probable adverse effects guidelines to marine organisms suggesting that trace elements redistributed by Hurricane Katrina would not cause an adverse impact on resident organisms. Instead, the concentrations of trace elements were site-dependent, with specific contaminants relating to the use of the area prior to Hurricane Katrina.  相似文献   
983.
Environmental pollution and climate change are requiring new methods to clean pollutants and produce sustainable energy. Aerogels and metal organic frameworks are emerging as advanced porous materials with higher functionality, high surface area, high porosity and flexible chemistry. Aerogels are dried gels prepared using the sol–gel procedure, whereas metal organic frameworks are networks of organic ligands and metal ions connected by coordination bonds. Applications of aerogels include the removal of heavy metals, CO2 capture and reduction, photodegradation of pollutants, air cleanup and water splitting. This article reviews the synthesis and types of aerogels and metal organic frameworks, and the application to pollutant removal, energy production including hydrogen, methane reforming, CO2 conversion and NOx removal.  相似文献   
984.
Which task a social insect worker engages in is influenced by the worker’s age, genotype and the colony’s needs. In the honeybee, Apis mellifera, genotype influences both the age a worker switches tasks and its propensity of engaging in specialist tasks, such as water collecting, which only some workers will perform. In this study, we used colonies with natural levels of genetic diversity and manipulated colony age demography to drastically increase the stimuli for the generalist tasks of foraging and nursing, which all workers are thought to engage in at some point in their lives. We examined the representation of worker patrilines engaged in nursing and foraging before and after the perturbation. The representation of patrilines among foragers and nurses differed from that of their overall colony’s population. In the case of foraging, over- and underrepresentation of some patrilines was not simply due to differences in rates of development among patrilines. We show that replacement foragers tend to be drawn from patrilines that were overrepresented among foragers before the perturbation, suggesting that there is a genetic component to the tendency to engage in foraging. In contrast, the representation of patrilines in replacement nurses differed from that in the unperturbed nursing population. Our results show that there is a genetic influence on even the generalist tasks of foraging and nursing, and that the way patrilines in genetically diverse colonies respond to increases in task stimuli depends upon the task. The possible significance of this genetic influence on task allocation is discussed. Electronic supplementary material Supplementary material is available in the online version of this article at doi: and is accessible to authorized users.  相似文献   
985.
A poly(lactic acid) (PLA)/polyamide 11 (PA11)/SiO2 composite was mixed from PLA, PA11, and nanosilica particles through twin-screw extrusion. The PLA/PA11/SiO2 composite was evaluated with tensile and Izod impact tests, light transmission and haze measurement, and isothermal and nonisothermal crystallization behavior determinations. The PLA/PA11/SiO2 (97.0/3.0) composite had approximately 10.8% less ultimate tensile strength than neat PLA, but it had greater ductility and approximately ninefold greater elongation at break. A dimple morphology was observed on the fractural surface of the PLA/PA11/SiO2 composite, indicating that the incorporation of PA11 and nanosilica particles increased the ductility of the PLA matrix. PLA with less than 3 wt% of PA11 and 0.5 phr of nanosilica particles had an Izod impact strength of 8.72 kJ/m2. PA11 and nanosilica particles effectively toughened this PLA polymer; they accelerated both isothermal and nonisothermal crystallization rates and increased the crystallinities of the resulting composites under isothermal and nonisothermal crystallization processes.  相似文献   
986.
Channa argus, a type of snakehead fish native to China, is a popular food fish in certain Asian countries but is a known destructive invasive species in the US. In this study, the two collagens, i.e. acid-soluble collagen (ASC) and pepsin-solubilized collagen (PSC), were obtained from C. argus skin. The yield of ASC was 28.0% and that of PSC was 16.8% on the dry bases. The collagens were identified as the collagen of type I by SDS–PAGE patterns. The Tds were approximately 27.0?°C. Similar ultraviolet spectra of both collagens were observed. Fourier Transform infrared spectra indicated PSC structure had a little change due to the loss of terminal domains by pepsin digestion. The results of XRD proved that the two collagens retained their helical structures. The results suggest that the collagens isolated from C. argus can potentially be alternative sources of vertebrate collagens for use in the food and other industries.  相似文献   
987.
Environmental Science and Pollution Research - In the paper, the pollution of playgrounds in Lublin with heavy metals was assessed. Since playgrounds are a place of activity of children—the...  相似文献   
988.
Environmental Science and Pollution Research - Rapid weather phenomena, particularly sudden and intense rainfall, have become a problem in urban areas in recent years. During heavy rainfall, urban...  相似文献   
989.
Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org/10.1007/s11356-020-11749-1  相似文献   
990.
Dendrogeomorphology is a powerful tool to determine past avalanche activity, but whether or not the obtained annually resolved chronologies are sufficiently detailed to infer avalanche–climate relationships (in terms of temporal resolution) remains an open question. In this work, avalanche activity is reconstructed in five paths of the French Alps and crossed with a set of snow and weather variables covering the period 1959–2009 on a monthly and annual (winter) basis. The variables which best explain avalanche activity are highlighted with an original variable selection procedure implemented within a logistic regression framework. The same approach is used for historical chronologies available for the same paths, as well as for the composite tree-ring/historical chronologies. Results suggest that dendrogeomorphic time series allow capturing the relations between snow or climate and avalanche occurrences to a certain extent. Weak links exist with annually resolved snow and weather variables and the different avalanche chronologies. On the contrary, clear statistical relations exist between these and monthly resolved snow and weather variables. In detail, tree rings seem to preferentially record avalanches triggered during cold winter storms with heavy precipitation. Conversely, historical avalanche data seem to contain a majority of events that were released later in the season and during episodes of strong positive temperature anomalies.  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