全文获取类型
收费全文 | 6196篇 |
免费 | 454篇 |
国内免费 | 496篇 |
专业分类
安全科学 | 2582篇 |
废物处理 | 285篇 |
环保管理 | 838篇 |
综合类 | 2069篇 |
基础理论 | 343篇 |
环境理论 | 9篇 |
污染及防治 | 249篇 |
评价与监测 | 229篇 |
社会与环境 | 260篇 |
灾害及防治 | 282篇 |
出版年
2024年 | 10篇 |
2023年 | 51篇 |
2022年 | 105篇 |
2021年 | 195篇 |
2020年 | 203篇 |
2019年 | 211篇 |
2018年 | 105篇 |
2017年 | 427篇 |
2016年 | 264篇 |
2015年 | 510篇 |
2014年 | 256篇 |
2013年 | 293篇 |
2012年 | 441篇 |
2011年 | 379篇 |
2010年 | 323篇 |
2009年 | 315篇 |
2008年 | 253篇 |
2007年 | 390篇 |
2006年 | 452篇 |
2005年 | 385篇 |
2004年 | 314篇 |
2003年 | 263篇 |
2002年 | 157篇 |
2001年 | 118篇 |
2000年 | 124篇 |
1999年 | 104篇 |
1998年 | 76篇 |
1997年 | 67篇 |
1996年 | 53篇 |
1995年 | 56篇 |
1994年 | 33篇 |
1993年 | 36篇 |
1992年 | 26篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1986年 | 5篇 |
1985年 | 12篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 6篇 |
排序方式: 共有7146条查询结果,搜索用时 15 毫秒
1.
Ismael A.S. Ehtiwesh Fernando Neto Da Silva Antonio C.M. Sousa 《International Journal of Green Energy》2019,16(1):72-85
The study addresses the potential of using concentrated solar power plants (CSPs) as a sustainable alternative of clean energy generation in the Mediterranean region and, in particular, in its North Africa shore. This location presents attractive conditions for the installation of CSPs, in particular high solar irradiation, good manpower concentration, and proximity and availability of water resources for condenser cooling. Energetic, exergetic, and economic analyses were conducted taking into consideration a particular type of CSPs - the parabolic trough concentrated solar power plant, which incorporates the most proven technology and it is already used in Southern Europe (Spain). In addition, the study considered the impact of project financing and incentives on the cost of energy. The combination of higher values for performance and potentially lower levelized cost of electricity (LCE) for the North Africa Mediterranean Rim than the South of Spain region can yield a very favorable return for the invested capital. Tripoli compared to Almeria presented superior performance and potentially lower LCE values ($0.18/kWh versus $0.22/kWh). This is significant, even when it is taken into consideration the fact that the plant in Tripoli, despite a relatively modest capacity factor of 34%, has a large gross power output of 173,886 MWhe. In addition, the implementation at the Tripoli location of a plant similar to the Anadsol plant has a slight advantage (2–3%) in terms of overall efficiency. 相似文献
2.
Complex systems often experience a long period of incubation before accidents occur. Therefore, a proactive risk assessment is essential for process safety. The conventional job hazard analysis (JHA) method has been an effective tool to conduct a process risk assessment in the high-risk industrial field. However, the conventional JHA is inadequate for the proactive risk assessment since it is usually conducted during and before one specific operation process. Operations such as startup and maintenance are performed repeatedly on the lifecycle of a plant. Therefore, the risk reduction measures for the industrial process should include not only preventive actions obtained from the conventional JHA but also recovery ones. Resilience engineering (RE) has proven to be helpful for the recovery analysis of a complex system. The objective of this paper is to propose a proactive and comprehensive process risk assessment approach based on JHA and RE. The mechanism of applying RE to address operation process risk is illustrated. The integrated approach can provide guidelines to establish proactive risk reduction measures as well as maintain a low-risk level. Finally, a gas transmission startup process risk assessment case is presented to demonstrate its applicability. 相似文献
3.
4.
The most widely used method for fetocide in late termination of pregnancy for fetal abnormalities (TOPFA) consists of injecting of potassium chloride (KCl) into the fetal heart and is likely to be painful after 22 weeks of gestation. We studied ten consecutive women undergoing TOPFA between 22 and 38 weeks. This technique for fetocide consisted of a single umbilical vein puncture under ultrasound guidance with injections of sufentanil 5 µg followed by KCl 2 g. No electrocardiographic modifications could be observed and maternal plasma potassium levels did not show any significant variation throughout the procedure. Fetal umbilical phlebotomy for fetal analgesia followed by fetocide therefore appears to be a safe procedure for the mother and allows the fetus to die without pain when late termination of pregnancy (TOP) is indicated. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
5.
采样点位置的确定是烟尘测试中的一项基础工作。在全国沿用10多年的确定圆形圆形烟道烟尘采样点位置的计算表中的数据,经验算有60%有误;原来以烟道中心为基准的计算公式虽然正确,但实用性差。为了进一步完善烟气测试理论,提高监测质量,提出以烟道内壁为基准的新计算公式。运用新、旧2种计算公式得到一致的计算结果—新计算表,进一步证实了原计算表中的错误。 相似文献
6.
资源型城市可持续发展能力的演变与调控 总被引:16,自引:0,他引:16
作为特殊的经济区,资源型城市的衰落与振兴日益成为社会关注的热点。本文从分析资源型城市可持续发展能力入手,论述了资源型城市发展能力的成长阶段及演变特征,提出了资源城市可持续发展能力调控的模式和途径。 相似文献
7.
本文简要介绍区域性“减灾十年初步规划”编制的一般原则,包括规划编制的意义、目的、编制顺序和规划应注意的几个方面,并提出规划成果的实施意见。可供各地编制规划时参考。 相似文献
8.
模拟废印刷线路板(WPCB)的热拆解过程,分析热拆解过程中的挥发性有机物(VOCs)组分;利用真实溶剂似导体屏蔽(COSMO-RS)模型对浓度较高的污染物进行量子力学模拟,研究离子液体(ILs)组成单元对目标污染物溶解度的影响差异,分析溶解过程中主导分子间作用力类型,确定优选吸收剂;测定不同溶剂进行溶解性,验证模型适用性.结果表明:①乙酸乙酯和环戊酮是浓度较高的VOCs组分,在240和250℃时浓度分别为43.1,153mg/m3和105,252mg/m3,质量百分比总和分别为76.3%和67.3%.②高表面屏蔽电荷密度分布峰、长烷基链阴阳离子和亲电基团的存在可提高乙酸乙酯和环戊酮在ILs中的溶解度.双三氟甲磺酰基亚胺盐(NTf2-)类ILs是一类优良吸收剂.静电力和范德华力对溶解过程起主导作用.③COSMO-RS模型可定性和半定量用于预测乙酸乙酯和环戊酮的溶解度. 相似文献
9.
Based on density functional theory (DFT) and basic structure models, the chemical reactions on the surface of vanadium-titanium based selective catalytic reduction (SCR) denitrification catalysts were summarized. Reasonable structural models (non-periodic and periodic structural models) are the basis of density functional calculations. A periodic structure model was more appropriate to represent the catalyst surface, and its theoretical calculation results were more comparable with the experimental results than a non-periodic model. It is generally believed that the SCR mechanism where NH3 and NO react to produce N2 and H2O follows an Eley-Rideal type mechanism. NH2NO was found to be an important intermediate in the SCR reaction, with multiple production routes. Simultaneously, the effects of H2O, SO2 and metal on SCR catalysts were also summarized. 相似文献
10.
Ozone (O3), as a harmful air pollutant, has been of wide concern. Safe, efficient, and economical O3 removal methods urgently need to be developed. Catalytic decomposition is the most promising method for O3 removal, especially at room temperature or even subzero temperatures. Great efforts have been made to develop high-efficiency catalysts for O3 decomposition that can operate at low temperatures, high space velocity and high humidity. First, this review describes the general reaction mechanism of O3 decomposition on noble metal and transition metal oxide catalysts. Then, progress on the O3 decomposition performance of various catalysts in the past 30 years is summarized in detail. The main focus is the O3 decomposition performance of manganese oxides, which are divided into supported manganese oxides and non-supported manganese oxides. Methods to improve the activity, stability, and humidity resistance of manganese oxide catalysts for O3 decomposition are also summarized. The deactivation mechanisms of manganese oxides under dry and humid conditions are discussed. The O3 decomposition performance of monolithic catalysts is also summarized from the perspective of industrial applications. Finally, the future development directions and prospects of O3 catalytic decomposition technology are put forward. 相似文献