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   1104篇
  免费   87篇
  国内免费   246篇
安全科学   325篇
废物处理   22篇
环保管理   153篇
综合类   521篇
基础理论   227篇
污染及防治   104篇
评价与监测   15篇
社会与环境   43篇
灾害及防治   27篇
  2024年   2篇
  2023年   10篇
  2022年   16篇
  2021年   22篇
  2020年   37篇
  2019年   26篇
  2018年   19篇
  2017年   41篇
  2016年   35篇
  2015年   37篇
  2014年   47篇
  2013年   93篇
  2012年   92篇
  2011年   100篇
  2010年   73篇
  2009年   70篇
  2008年   51篇
  2007年   97篇
  2006年   113篇
  2005年   79篇
  2004年   61篇
  2003年   55篇
  2002年   32篇
  2001年   28篇
  2000年   21篇
  1999年   30篇
  1998年   18篇
  1997年   15篇
  1996年   31篇
  1995年   19篇
  1994年   9篇
  1993年   7篇
  1992年   8篇
  1991年   5篇
  1990年   3篇
  1989年   3篇
  1988年   7篇
  1987年   2篇
  1986年   3篇
  1985年   1篇
  1984年   5篇
  1983年   4篇
  1982年   4篇
  1981年   2篇
  1978年   2篇
  1977年   1篇
  1971年   1篇
排序方式: 共有1437条查询结果,搜索用时 687 毫秒
891.
本文研究碳源调控磷回收强化生物脱氮除磷(biological bio-nutrient removal-carbon regulation and phosphorus recovery,BBNR-CPR)反应器耐低温特性.不断降低BBNR-CPR反应器运行温度,发现BBNR-CPR反应器能够长期在低温(≤15℃)、低C/N比(<4.16)条件下稳定运行,维持总磷的平均去除率为91.20%,氨氮的平均去除率为81.10%,总氮的平均去除率为58.62%.随着运行时间的增加与温度的下降,BBNR-CPR反应器生物内膜具有脱氮除磷以及PHA贮存功能的种属Candidatus_Competibacter、Candidatus_Accumulibacter、Run-SP 154、Thauera、Candidatus_Nitrotoga的相对丰度不断提高,成为耐受低温条件的优势种属.在相同碳源浓度、合成PHA的时间一致的条件下,生物膜内PHA的合成量受温度影响;25、15和8℃合成的PHA量分别占生物膜干重的16.24%、11.49%和9.01%.预贮存PHA的生物膜具有耐受低温的能力;在高PHA水平,8℃和15℃的除磷效率分别为97.46%和100%,脱氮效率分别为55.15%和82.55%;而在低PHA水平,8℃和15℃的除磷效率分别为11.39%和35.02%,脱氮效率分别为0%和12.10%.  相似文献   
892.
针对海洋文化产业发展战略研究中缺乏定量分析的不足,将SWOT分析法和层次分析法相结合,通过量化各影响因素的权重,得出薄弱的海洋文化产业综合竞争力和海洋文化人才队伍建设是制约秦皇岛海洋文化产业发展的关键因素.论证了秦皇岛海洋文化产业应充分利用资源禀赋丰富的优势,抓住国家战略政策机遇,采取开拓型战略,积极应对各种劣势和威胁,走“以海洋文化产业资源为依托,以海洋旅游产业为主导”的核心产业带动发展模式.  相似文献   
893.
选取2000~2010年为时间断面,以江西省为研究对象,利用第五、第六次人口普查数据和统计年鉴,结合Arcgis、Geoda、SPSS软件和主成分分析、回归分析等方法,测算文化素质指数,分析人口文化素质概况并研究其空间格局演变,从赣北、赣中、赣南三大区域和地级市两大角度分析人口文化 城市匹配程度。研究发现:(1)人口文化素质指数在空间上以低低聚集为主,高素质人口仍聚集在赣北地区;(2)文化 城市偏移状况得到改善,由区域差异较大向均衡发展;(3)赣北、赣中、赣南三大区域均属于文化主导,其中赣北地区文化 城市逐渐匹配,赣中、赣南地区偏离度增加,文化主导加剧;地级市匹配状态总体较好,3种类型均有分布  相似文献   
894.
Based on the sociotechnical systems approach, an understanding of safety culture as deeply rooted assumptions about the interplay of people, technology, and organization in their relation to safety is presented. As a complement to audit methods aimed at assessing formal safety management, a questionnaire was developed which allows some indications of these assumptions to be captured by providing data on perceptions regarding operational safety, safety and design strategies, and personal job needs. Analyzing response patterns of different occupational, hierarchical, and organizational groups within a company in combination with formal audit results and the communicative validation of both in a feedback meeting can help the auditors as well as the members of the company to gain a deeper understanding of safety management and safety culture in that company. Results from seven audits in petrochemical plants are presented and discussed with respect to the validity and practicability of the chosen approach.  相似文献   
895.
绿色文化探析   总被引:9,自引:0,他引:9  
绿色文化以生态学理论为指导,以可持续发展为根本目标,是人类思想领域的又一次深刻劳动保险。从绿色思想,绿色科技到人们日常生活密切相关的绿色工业产品,绿色食品,绿色消费,绿色包装,绿色文学 ,绿色文化已渗透到人类社会生活的各个领域。  相似文献   
896.
897.
Although researchers have often found positive relationships between organizational citizenship behavior (OCB) and performance rating, very few studies have scrutinized the team contexts in which such relationships exist. This study examines how OCB influences job performance ratings within different team cultures, as measured by team collectivism and individualism. On the basis of multilevel data collected from 81 teams working at a multinational bank in Hong Kong, team collectivism and individualism were found to moderate the OCB–performance rating relationship such that OCB targeting individuals improved rated performance in highly collectivistic teams only, whereas only organizational OCB produced a significant improvement in highly individualistic teams. The implications of these findings and directions for future research directions are discussed here. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
898.
Globalization and technology transfer have led to the diffusion of risk communications to users from cultures that were not initially viewed as the target users. This study examined industry and trade workers’ overall impressions of symbols used to convey varying degrees of hazardousness. Six symbols, including symbols from the American National Standards Institute (ANSI) Z535 Standard (ANSI, 1998) and the International Organization for Standardization (ISO) 3864:1984 Standard (ISO, 1984) were selected. With the exception of the SKULL symbol, results showed wide discrepancies between users’ perceptions of the symbols and their intended meanings. Implications for cross-cultural research on warning components and risk communications are discussed.  相似文献   
899.
One of the dimensions treated as part of a company’s safety culture or climate is workers’ attitudes towards risk and safety. In the present study these personal aspects are defined as workers’ safety culture, which is understood as a way of acting focused on life and taking care of one’s health. A questionnaire on safety culture was filled out by 200 employees of a metallurgical enterprise. Factor analysis was used to determine empirical scales of the questionnaire, whereas variance analysis was used to test hypotheses. The results confirmed the hypotheses that people who experienced accidents, dangerous situations, and—to a lesser extent—health problems had a lower level of safety culture. Nevertheless not all of the scales determined during factor analysis turned out to be significant as far as all kinds of those undesirable situations are concerned. Proposals for future studies are formulated in the conclusion.  相似文献   
900.
The influence of culture conditions on the ultrastructure and enzyme activities of amniotic fluid cells are reported. Morphological changes were determined as a function of the number of lysosomal-like inclusion bodies per cell, and these results correlated to the activity of Thiexosaminidase, a-mannosidase, β-glucuronidase, arylsulphatase C and 5′ nucleotidase. The parameters examined were pH of the culture media, type of media, increasing cell passage and day of harvest. Our results indicate that enzyme activities are less sensitive to changes in culture conditions as compared to ultrastructural changes. We therefore recommend that in order to obtain reliable ultrastructural results for the diagnosis of storage disorders, cultures should be grown in MEM as the culture medium, the pH of the medium carefully monitored to remain below pH 7·4, examining the cultures no later than the eighth cell passage and no later than the 10th day after subculture.  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