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   5735篇
  免费   81篇
  国内免费   55篇
安全科学   142篇
废物处理   377篇
环保管理   474篇
综合类   692篇
基础理论   1213篇
环境理论   9篇
污染及防治   2030篇
评价与监测   528篇
社会与环境   382篇
灾害及防治   24篇
  2023年   70篇
  2022年   165篇
  2021年   212篇
  2020年   88篇
  2019年   102篇
  2018年   219篇
  2017年   221篇
  2016年   324篇
  2015年   193篇
  2014年   335篇
  2013年   556篇
  2012年   369篇
  2011年   419篇
  2010年   280篇
  2009年   220篇
  2008年   337篇
  2007年   355篇
  2006年   261篇
  2005年   208篇
  2004年   155篇
  2003年   135篇
  2002年   136篇
  2001年   87篇
  2000年   60篇
  1999年   43篇
  1998年   25篇
  1997年   19篇
  1996年   18篇
  1995年   31篇
  1994年   15篇
  1993年   16篇
  1992年   8篇
  1991年   11篇
  1990年   14篇
  1989年   6篇
  1988年   9篇
  1983年   3篇
  1982年   3篇
  1967年   8篇
  1966年   7篇
  1965年   3篇
  1964年   13篇
  1963年   8篇
  1962年   10篇
  1960年   6篇
  1959年   6篇
  1958年   23篇
  1957年   9篇
  1956年   6篇
  1955年   4篇
排序方式: 共有5871条查询结果,搜索用时 15 毫秒
91.
A variety of factors can influence an individual’s choice of within-group spatial position. For terrestrial social animals, predation, feeding success, and social competition are thought to be three of the most important variables. The relative importance of these three factors was investigated in groups of ring-tailed coatis (Nasua nasua) in Iguazú, Argentina. Different age/sex classes responded differently to these three variables. Coatis were found in close proximity to their own age/sex class more often than random, and three out of four age/sex classes were found to exhibit within-group spatial position preferences which differed from random. Juveniles were located more often at the front edge and were rarely found at the back of the group. Juveniles appeared to choose spatial locations based on feeding success and not predation avoidance. Since juveniles are the most susceptible to predation and presumably have less prior knowledge of food source location, these results have important implications in relation to predator-sensitive foraging and models of democratic group leadership. Subadults were subordinate to adult females, and their relationships were characterized by high levels of aggression. This aggression was especially common during the first half of the coati year (Nov–April), and subadults were more peripheralized during this time period. Subadults likely chose spatial positions to avoid aggression and were actively excluded from the center of the group by adult females. In the Iguazú coati groups, it appeared that food acquisition and social agonism were the major determinants driving spatial choice, while predation played little or no role. This paper demonstrates that within-group spatial structure can be a complex process shaped by differences in body size and nutritional requirements, food patch size and depletion rate, and social dominance status. How and why these factors interact is important to understanding the costs and benefits of sociality and emergent properties of animal group formation.  相似文献   
92.
Rice straw can be used as a renewable fuel for heat and power generation. It is a viable mean of replacing fossil fuels and preventing pollution caused by open burning, especially in the areas where this residual biomass is generated. Nevertheless, the thermal conversion of rice straw can cause some operating problems such as slag formation, which negatively affects thermal conversion systems. So, the main objective of this research is studying the combustion behavior of rice straw samples collected from various regions by applying thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). In addition, the thermal behavior of ashes from rice straw was also analyzed in order to detect their melting points, and ash sintering was detected at different temperatures within the range between 550 and 1000 °C. Since washing rice straw with water could reduce the content of undesirable inorganic compounds related to the ash fusibility, samples of washed rice straw were analyzed under combustion conditions to investigate its differences regarding the thermal behavior of rice straw. The results showed that rice straw washing led to a significant improvement in its thermal behavior, since it reduced the ash contents and sintering formation.  相似文献   
93.
94.
Environmental Science and Pollution Research - For the photocatalytic degradation of antioxidant 2,6-di-tert-butyl-hydroxytoluene (BHT), several TiO2-based composites have been prepared in MWCNT...  相似文献   
95.
Environmental Science and Pollution Research - The order Odonata has been regularly used as an indicator of the ecosystem’s condition. The objective of this review was to analyze the...  相似文献   
96.
Environmental Science and Pollution Research - In this study, the photocatalytic degradation of four fungicides, myclobutanil, penconazole and difenoconazole (triazole compounds) and boscalid...  相似文献   
97.
Environmental Science and Pollution Research - In this work, the activated persulfate oxidation of ciprofloxacin (CIP) using a low-grade titanium ore under sunlight or simulated sunlight were...  相似文献   
98.
Environmental Science and Pollution Research - This work proposes a novel approach for the coupling of ozonation and Fenton processes using a new prototype of a high rotation bubble reactor (HRBR),...  相似文献   
99.
Environmental Science and Pollution Research - The process TiO2/PAC/UV-vis has been under study and compared with the isolated treatments of adsorption and photocatalysis determining possible...  相似文献   
100.
Environmental Science and Pollution Research - Banana is one of the most important agricultural products of Ecuador. It relies on intensive monoculture cropping systems with a large volume of...  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