全文获取类型
收费全文 | 1479篇 |
免费 | 281篇 |
国内免费 | 389篇 |
专业分类
安全科学 | 439篇 |
废物处理 | 72篇 |
环保管理 | 224篇 |
综合类 | 877篇 |
基础理论 | 135篇 |
环境理论 | 1篇 |
污染及防治 | 169篇 |
评价与监测 | 107篇 |
社会与环境 | 72篇 |
灾害及防治 | 53篇 |
出版年
2024年 | 17篇 |
2023年 | 45篇 |
2022年 | 79篇 |
2021年 | 97篇 |
2020年 | 93篇 |
2019年 | 95篇 |
2018年 | 96篇 |
2017年 | 87篇 |
2016年 | 117篇 |
2015年 | 98篇 |
2014年 | 111篇 |
2013年 | 190篇 |
2012年 | 170篇 |
2011年 | 142篇 |
2010年 | 109篇 |
2009年 | 80篇 |
2008年 | 63篇 |
2007年 | 83篇 |
2006年 | 79篇 |
2005年 | 65篇 |
2004年 | 52篇 |
2003年 | 38篇 |
2002年 | 26篇 |
2001年 | 19篇 |
2000年 | 22篇 |
1999年 | 17篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有2149条查询结果,搜索用时 589 毫秒
631.
基于协调度与熵权法的绩效评价新方法 总被引:2,自引:0,他引:2
自人们意识到绩效评价的重要性以来,越来越多的研究集中于绩效评价的方法。以往的绩效评价侧重用数字表象进行评价,而忽略了政府、企业系统及其与社会经济发展之间的特性。基于此,根据既有的信息熵理论研究成果,提出了协调度与熵权法复合评价模型,并运用该模型对2009年度河北省区域创新绩效进行了实证分析,既科学、全面地衡量绩效情况,又便于政府、企业及其与社会经济发展之间的系统分析,是一种绩效评价方法的创新,具有一定的普适性和通用性。 相似文献
632.
633.
634.
丁酸钠对肉鸭生长及粪便中污染物减排效果的影响 总被引:1,自引:0,他引:1
在樱桃谷肉鸭的基础日粮中添加丁酸钠,研究了丁酸钠对肉鸭生产性能及粪便中污染物含量和排放量的影响.结果表明,添加350、700和1 050 mg·kg-1丁酸钠处理(试验组2、3、4)料重比较对照(试验组1)均显著降低,分别降低4.95%、6.71%和4.59%(P<0.05),0~3周试验组3和4肉鸭日增质量较对照提高9.16%和9.47%(P<0.05);添加丁酸钠可显著降低鸭粪中TN、TP、氨氮、有机质、Cu和Zn含量(P<0.05),试验组3对TN、TP、氨氮和Zn的降低效果最好,分别较对照组减少6.15%、17.36%、59.98%和18.96%;不同水平丁酸钠处理鸭粪中污染物排放量均较对照显著降低(P<0.05),试验组3对污染物TN、TP、氨氮、有机质和Zn的减排效果最好,而试验组4对Cu的减排效果最佳.在肉鸭饲料中添加700 mg·kg-1丁酸钠可获得最佳的生产性能和减排效果. 相似文献
635.
Research has shown a complex relationship between turnover and firm performance. Not only does it matter who leaves (e.g., high‐performing versus low‐performing employees), but the context also stands to influence this effect in complex ways. We apply human capital theory, social capital theory, and the cost–benefit perspective to propose two boundary conditions to the high‐performer turnover and firm performance relationship. Specifically, we predict that the negative impact of high‐performer turnover on firm performance will be the strongest for reputable firms and for firms who invest less in human capital (e.g., selection, training, and incentive‐based pay). We present data from 155 South Korean firms that support the hypothesized model. We discuss findings in terms of current and future theory, practical implications, and subsequent research needs. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
636.
Ann-Sofie Lindberg Christer Malm Juha Oksa Désirée Gavhed 《International journal of occupational safety and ergonomics》2013,19(2):309-321
Objectives. The present study sought to identify firefighters’ rated physical demands for the most frequently occurring work tasks and to determine if the ratings differed between full-time and part-time firefighters to help create a basis for the development of physical employment tests for firefighters. Methods. An extensive questionnaire was completed by 125 and 68 firefighters in 2000 and 2010, respectively. The data were analysed with the Mann-Whitney U test and binominal test and ranked on the basis of the responses in each category. Results. Significant differences were seen between the full- and part-time firefighters. The work tasks rated as the most physically strenuous in terms of aerobic fitness, muscle strength, work posture and body control by most respondents were smoke diving upstairs (carrying a hose), victim rescue in different ways, carrying a stretcher over terrain and pulling a hose. Conclusions. Physically strenuous work tasks should be included in the end-point performance variables used to select physical performance tests for firefighters. The part-time firefighters with no experience in several of the work tasks suggests that work-related exercises are important if both groups of firefighters are expected to do similar work. 相似文献
637.
Iqbal Ahmed Khan Zulquernain Mallick 《International journal of occupational safety and ergonomics》2013,19(2):127-136
This paper presents a study in which the main objective was to investigate the combined effect of noise and vibration on the performance of a readability task in a mobile driving environment. Subjects performed a readability task on a laptop computer in a sitting posture with their backs supported with a backrest under varying levels of noise and vibration. The data in terms of the mean number of characters read per minute were collected and statistically analyzed. Results showed that the individual effect of noise, vibration, and the operators’ gender as well as the interaction between gender and noise, and gender and vibration were statistically significant. However, the combined effect of noise and vibration was not found to be statistically significant. Results also indicated that gender was statistically significant at all levels of noise as well as vibration, and noise and vibration were statistically significant at both levels of gender. 相似文献
638.
热防护服是热环境下人体安全防护的主要装备,其标准的科学性和系统性对热环境下的人体安全防护具有重要的支持作用.国外对热防护服相关的技术标准予以充分重视,以性能测试技术方法为主体,建立了较为科学、完善的标准,并体现出新的发展趋势.通过对国外热防护服技术标准的调研,总结性能测试标准的共性内容,包括主要性能测试方法、实验设备、实验步骤、烧伤评估、人体模型和测试报告等.整套防护服装的性能测试技术及标准是研究的重点,出汗暖体假人将在防护服装性能测试领域被更为广泛的应用.最后,提出我国研制热防护服性能测试技术标准的建议. 相似文献
639.
As widely recognised by EU legislation, Life Cycle Thinking (LCT) is a viable approach to support sound waste management choices. In this context, the Institute for Environment and Sustainability (IES) of the European Commission Joint Research Centre (JRC) has lead the development of macro-level, life cycle based waste management indicators to quantify and monitor the potential environmental impacts, benefits, and improvements associated with the management of a number of selected waste streams generated and treated in Europe.The waste management indicators developed make use of a combination of macro statistical waste management data combined with emissions/resource life cycle data for the different elements of the waste treatment chain. Indicators were initially calculated for the entire European Union (EU-27) and for Germany, covering several waste streams and a broad range of environmental impact categories.An indicator developed for a given waste stream captures the potential environmental impact associated with the generation and management of that waste stream. The entire waste management chain is considered, i.e. from generation to final treatment/disposal. Therefore, system boundaries for the selected waste streams include also the treatment or recycling of secondary waste (e.g. bottom ash from the incineration of household waste), and secondary products (e.g. recovered paper), as well as energy recovery.The experiences from the development of these life cycle based waste management indicators suggest that more detailed and quality-assured waste statistics are needed, especially covering the many different treatment operations and options. Also, it would be beneficial if waste statistics had a higher disaggregation level of waste categories, as well as more detailed information about waste composition. A further development of the indicators should include an increased number of waste streams, as well as calculation of the results for all Member States. 相似文献
640.
We analyze the process of landfill diversion and its main determinants, by embedding the dynamics in a frame where economic, geographical and policy variables come into play. In addition to structural and economic drivers, we primarily investigate whether the Italian tax has been effective in supporting landfill diversion. Although the Italian landfill tax dates back to 1996, the oldest in the EU, its effectiveness in terms of landfill diversion has not been assessed yet. The complexity primarily derives from the decentralized regional implementation and the absence of a full coherent dataset covering all regions. We merge this new and original data on taxes to an integrated dataset which includes economic, waste and policy variables at regional level over the period 1999–2008. Panel regressions show that the effect of tax is significant, even when taking into account for its possible endogeneity. Regions that have increased such taxes have improved waste disposal performances over time. Landfill taxes are surely not the only instrument policy makers might introduce, but they seem to play a relevant role in the evolution of Italian waste disposal performances. 相似文献