全文获取类型
收费全文 | 7528篇 |
免费 | 364篇 |
国内免费 | 171篇 |
专业分类
安全科学 | 600篇 |
废物处理 | 100篇 |
环保管理 | 1958篇 |
综合类 | 3394篇 |
基础理论 | 460篇 |
环境理论 | 21篇 |
污染及防治 | 378篇 |
评价与监测 | 699篇 |
社会与环境 | 366篇 |
灾害及防治 | 87篇 |
出版年
2024年 | 9篇 |
2023年 | 47篇 |
2022年 | 74篇 |
2021年 | 135篇 |
2020年 | 245篇 |
2019年 | 120篇 |
2018年 | 105篇 |
2017年 | 189篇 |
2016年 | 212篇 |
2015年 | 202篇 |
2014年 | 326篇 |
2013年 | 370篇 |
2012年 | 341篇 |
2011年 | 546篇 |
2010年 | 323篇 |
2009年 | 436篇 |
2008年 | 334篇 |
2007年 | 431篇 |
2006年 | 438篇 |
2005年 | 284篇 |
2004年 | 294篇 |
2003年 | 335篇 |
2002年 | 306篇 |
2001年 | 298篇 |
2000年 | 327篇 |
1999年 | 261篇 |
1998年 | 197篇 |
1997年 | 195篇 |
1996年 | 125篇 |
1995年 | 101篇 |
1994年 | 95篇 |
1993年 | 108篇 |
1992年 | 59篇 |
1991年 | 34篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1978年 | 12篇 |
1977年 | 8篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有8063条查询结果,搜索用时 312 毫秒
941.
根据国家及行业协会的有关规定要求,环境污染治理设施运营资质认定的管理方式实行改革,资质证书管理已完成了从行政许可到行业自律管理的过渡。阐述了资质证书管理方式转变的意义和重要性,以及具体实行中需要注意的问题和对策。 相似文献
942.
943.
The formulation and scale-up of batch processes is one of the major challenges in the development of pharmaceutical dosage forms and at the same time a significant resource demanding process which is generally overlooked in environmental sustainability assessments. First, this paper proposes general trends in the experience curve of cumulative resource consumption of pharmaceutical tablet manufacturing of PREZISTA® 800 mg through wet granulation (WG) at four consecutive scales in both R&D and manufacturing environments (resp. WG1 = 1 kg/h, WG5 = 5 kg/h, WG30 = 30 kg/h and WG240 = 240 kg/h). Second, the authors aim at evaluating the environmental impact from a life cycle perspective of a daily consumption of PREZISTA® 2× 400 mg tablets versus the bioequivalent PREZISTA® 800 mg tablet which was launched to enhance patient compliance. Environmental sustainability assessment was conducted at three different system boundaries, which enables identification, localization and eventually reduction of burdens, in this case natural resource extraction. Exergy Analysis (EA) was used at process level (α) and plant level (β) while a cradle-to-gate Exergetic Life Cycle Assessment (ELCA) was conducted at the overall industrial level (γ) by means of the CEENE method (Cumulative Exergy Extraction from the Natural Environment). Life cycle stages taken into account are Active Pharmaceutical Ingredient (API) production, Drug Product (DP) production and Packaging. At process level (α), the total resource extraction for the manufacturing of one daily dose of PREZISTA® (800 mg tablet) amounted up to 0.44 MJex at the smallest scale (WG1) while this amount proved to be reduced by 58%, 79% and 83% at WG5, WG30 and WG240 respectively. Expanding the boundaries to the overall industrial level (γ) reveals that the main resource demand is at the production of the Active Pharmaceutical Ingredient (API), excipients, packaging materials and cleaning media used in DP production. At the largest scale (WG240) the use of cleaning media during DP production contributes considerably less to the total resource extraction. Overall, the effect of scale-up and learning on resource consumption during DP production showed to possess a power-law experience curve y = 2.40 * x−0.57 when shifting from WG1 (smallest lab scale) to WG240 (industrial manufacturing). Tablet dosage (2× 400 mg versus 1× 800 mg) did not significantly affect the absolute environmental burden. However, the relative contribution of resource categories did change due to the different production technology. It could be concluded that in meeting social and economic demands by launching the PREZISTA® 800 mg tablet, no trade-off in environmental burden occurred. On the long term, future research should strive to take into account R&D processes and all services related to pipeline activities taking place prior to market launch and eventually to allocate impacts to the final product. 相似文献
944.
945.
飞机的雷击附着点是飞机防雷设计研究的基础,是飞机设计中的重要过程。本文以伊尔-76飞机模型为例,依据SAE-ARP5416和国内相关标准规定的雷击附着点试验方法,采用基于传输线矩阵法的数值仿真技术对飞机的雷击附着特性展开研究,分析了机载雷达天线对飞机雷击附着点的影响,为机载雷达天线的雷电防护设计提供了理论基础。 相似文献
946.
947.
Cláudia Andrade Maria Luísa Lima Ferdinando Fornara Marino Bonaiuto 《Journal of environmental psychology》2012
Environmental Quality Perception (EQP) is an important construct used to help to understand the relationship between people and the hospital environment. From a patient-centered care perspective, it is important that hospital design take into account the patients' (and other users') point of view. This paper presents the adaptation and validation of a measure of hospital EQP, the Perceived Hospital Environment Quality Indicators (PHEQIs; Fornara, Bonaiuto, & Bonnes, 2006), and seeks to confirm the factor structure of this construct in a different cultural context. Three scales, two focusing on physical environments and one evaluating the social environment, were completed by 562 users of four orthopedic units in Portuguese hospitals, two older and two recently built or renovated. To assess criterion validity, hospital physical environments were also objectively evaluated by two architects. Using a confirmatory factor analysis the three validation procedures produced acceptable fit indices in the final measurement models. Overall reliability values were satisfactory, as was the evidence for criterion validity. PHEQIs scales and factors correlated with global evaluation of the environment, supporting concurrent criterion validity; and predictive criterion validity was demonstrated given that users of older and newer hospitals differed significantly on the perception of quality of hospital EQP, and that high congruence between users' and experts' evaluations was found. Discriminant construct validity was supported, and some difficulties in showing convergent validity are discussed in terms of item formulation adequacy. Implications for research and practice are described. 相似文献
948.
949.
This paper investigates the current status and trends over time in the environmental performance of European ports. The research is based on the provision of data from 79 European ports on issues related to their environmental management, environmental priorities and current environmental monitoring practices. This study updates previous environmental reviews, so that the trends over time are drawn. For instance, 90% of respondent ports stated that they have an environmental policy and 94% of ports have designated environmental personnel. The percentage of ports that have an Environmental Management System has increased by +33% in the last 9 years. Air quality, port waste and energy consumption emerged as the three major environmental priorities of the European port sector in 2013. The research also reveals the diversity amongst European ports in terms of size and physical surroundings. Some examples are presented on specific initiatives carried out by sector organisations about the Top-10 port priority issues. The future expectations of European ports on data collection and reporting are described. 相似文献
950.