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   6201篇
  免费   256篇
  国内免费   2223篇
安全科学   437篇
废物处理   339篇
环保管理   491篇
综合类   3337篇
基础理论   1113篇
环境理论   1篇
污染及防治   2187篇
评价与监测   273篇
社会与环境   250篇
灾害及防治   252篇
  2024年   14篇
  2023年   128篇
  2022年   316篇
  2021年   267篇
  2020年   213篇
  2019年   187篇
  2018年   263篇
  2017年   286篇
  2016年   257篇
  2015年   354篇
  2014年   490篇
  2013年   564篇
  2012年   530篇
  2011年   511篇
  2010年   383篇
  2009年   417篇
  2008年   453篇
  2007年   354篇
  2006年   348篇
  2005年   232篇
  2004年   173篇
  2003年   225篇
  2002年   216篇
  2001年   191篇
  2000年   180篇
  1999年   181篇
  1998年   192篇
  1997年   127篇
  1996年   126篇
  1995年   108篇
  1994年   97篇
  1993年   75篇
  1992年   68篇
  1991年   26篇
  1990年   27篇
  1989年   18篇
  1988年   20篇
  1987年   10篇
  1986年   9篇
  1985年   2篇
  1984年   4篇
  1983年   5篇
  1982年   5篇
  1981年   9篇
  1979年   4篇
  1977年   2篇
  1975年   2篇
  1973年   1篇
  1972年   3篇
  1971年   3篇
排序方式: 共有8680条查询结果,搜索用时 500 毫秒
891.
Environmental Geochemistry and Health - Heavy metals are considered important environmental contaminants, and their mixture toxicity on plants has complex mutual interactions. The interactive...  相似文献   
892.
Nowadays, more people tend to spend their recreational time in large national parks, and trace metal(loid)s in soils have attracted long-term attention due to their possible harm to human health. To investigate the pollution levels, potential sources and health risks of trace metal(loid)s in road soils, a total of eight trace metal(loid)s (including As, Cd, Cr, Cu, Ni, Pb, Zn and Hg) from 47 soil samples along roads were studied in the Huangshan National Park in Southeast China. The results showed that the concentrations of As, Cd, Pb, Zn and Hg appeared different degrees of pollution compared with their corresponding background values. According to the pollution indices, Hg and Cd were recognized as significant pollutants presenting moderate to high ecological risk. Combining principal component analysis and positive matrix factorization model, the results showed that traffic, industrial, agricultural and natural sources were the potential origins of trace metal(loid)s in this area, with contribution rates of 39.93%, 25.92%, 10.53% and 23.62%, respectively. Non-carcinogenic risks were all negligible, while the carcinogenic risk of As was higher than the limit (1 × 10−6). Moreover, children were more susceptible to trace metal(loid)s by ingestion which appeared to be a more important exposure pathway than dermal contact and inhalation. The contribution rates of different sources to non-carcinogenic risks and carcinogenic risks were similar among children and adults, while traffic and industrial sources have a significant impact on health risks. This study will give more insights to control the environmental risks of trace metal(loid)s in national parks.  相似文献   
893.
Environmental Science and Pollution Research - As one of the most important nutrients for plant growth, phosphorus was often poorly available in soil. While biochar addition induced improvement of...  相似文献   
894.
A novel sodium alginate-grafted poly(acrylic acid)/graphene oxide (NaAlg-g-PAA/GO) composite hydrogel was prepared via ultraviolet irradiation, and characterized by infrared spectroscopy spectrometer. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. It was employed to adsorb NH4+ from aqueous solution and used as slow-release nitrogen fertilizers (SNFs). Result indicated that the adsorption process for NH4+ reached equilibrium within 50 min, with the adsorption capacity of 6.6 mmol g?1 even if 30 wt% GO was incorporated. The results of adsorption kinetic and isotherm were well described by the pseudo-second-order and Freundlich model. The thermodynamics analysis showed the adsorption process was spontaneous. The study indicated excellent water-holding ratio of soil with 2 wt% SNFs was 81.2%, and nitrogen release was up to 55.1% within 40 days in soil. Overall, NaAlg-g-PAA/GO could be considered as an efficient adsorbent for the recovery of nitrogen with the agronomic reuse as a fertilizer.  相似文献   
895.
Environmental Science and Pollution Research - The disparity of tolerance in plants in response to Cd stress is associated with multiple physiological processes. A pot experiment was conducted to...  相似文献   
896.
897.
兰炭是榆林市的重要产业之一,但由于兰炭"粗放"的生产方式,对区域环境产生一定影响。为推进兰炭绿色健康发展,本文针对榆林市某园区内兰炭企业进行调研,了解该企业存在的主要问题,并提出相关建议。  相似文献   
898.
Introduction. This study aimed to examine the effectiveness of a physical activity (PA) program on weight control, physical fitness, occupational stress, job satisfaction and quality of life of overweight and sedentary employees in high-tech industries. Methods. Participants in the intervention group (n?=?37) were instructed to carry out a PA program at moderate intensity for 60?min/session, 3 sessions/week for 12 weeks. Those in the control group (n?=?38) received no PA program and were asked to continue their routine lifestyle. Evaluations were performed at baseline and at the end of the intervention. Results of structured questionnaires and blood biochemistry tests and evaluations of physical fitness were analyzed. Results. The PA program effectively reduced the number of risk factors for metabolic syndrome and body fat percentage, and improved physical fitness such as flexibility, muscular strength and endurance and cardiorespiratory endurance. The intervention also significantly decreased levels of serum triglyceride, total cholesterol and low-density lipoprotein cholesterol. Significant positive effects on work control, interpersonal relationships at work, global job satisfaction and quality of life were also demonstrated. Conclusion. This study showed that a PA program can be helpful in improving physical, physiological and psychological outcomes for overweight and sedentary employees in high-tech industries.  相似文献   
899.
评估RF多功能芯片在不同环境温度下的性能指标是十分重要的,从分析射频多功能芯片功能和主要性能指标出发,研制了一款自动化芯片在片评估系统。采用上位机进行多种芯片工作状态和设备仪器状态控制,实现了芯片在各种不同工作状态不同温度下的测试数据采集、判断和保存。经实际评估验证,该评估系统能高效高可靠性的完成射频多功能芯片在不同环境温度下的on-wafer级性能评估。  相似文献   
900.
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