全文获取类型
收费全文 | 3344篇 |
免费 | 246篇 |
国内免费 | 613篇 |
专业分类
安全科学 | 283篇 |
废物处理 | 80篇 |
环保管理 | 734篇 |
综合类 | 1696篇 |
基础理论 | 382篇 |
环境理论 | 1篇 |
污染及防治 | 285篇 |
评价与监测 | 59篇 |
社会与环境 | 588篇 |
灾害及防治 | 95篇 |
出版年
2024年 | 12篇 |
2023年 | 50篇 |
2022年 | 85篇 |
2021年 | 104篇 |
2020年 | 107篇 |
2019年 | 111篇 |
2018年 | 89篇 |
2017年 | 167篇 |
2016年 | 190篇 |
2015年 | 165篇 |
2014年 | 148篇 |
2013年 | 228篇 |
2012年 | 290篇 |
2011年 | 315篇 |
2010年 | 220篇 |
2009年 | 188篇 |
2008年 | 142篇 |
2007年 | 222篇 |
2006年 | 201篇 |
2005年 | 148篇 |
2004年 | 124篇 |
2003年 | 131篇 |
2002年 | 119篇 |
2001年 | 79篇 |
2000年 | 88篇 |
1999年 | 71篇 |
1998年 | 64篇 |
1997年 | 47篇 |
1996年 | 29篇 |
1995年 | 47篇 |
1994年 | 28篇 |
1993年 | 30篇 |
1992年 | 29篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1985年 | 5篇 |
1983年 | 5篇 |
1982年 | 13篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 7篇 |
排序方式: 共有4203条查询结果,搜索用时 15 毫秒
991.
氧化镁法脱硫,具有工艺流程短、脱硫效率高等优点,对控制烟气SO2造成的大气污染是一种行之有效的办法,具有推广应用的广阔前景。 相似文献
992.
葛曰刚 《中国环境管理干部学院学报》1999,(4)
环境保护与经济建设协调发展是实施可持续发展的重要环节。为使环境保护与经济建设协调发展,必须在发展社会经济中,建立并不断完善经济建设与环境保护综合决策机制。 相似文献
993.
李同明 《中国环境管理干部学院学报》1999,(4)
本文主要论述了把效率与公平的统一纳入可持续发展之中的新观念。首先阐述了可持续发展的深刻内涵及思想本质,然后论述了可持续发展的公平观(当代人之间的公平及代际公平),以及可持续发展的效率现。用可持续发展及“三个效益”统一的指导思想和观点,综合论述了可持续发展和公平、效率的统一性。 相似文献
994.
本文以福建省龙海市为例,分析了龙海市农业发展优势与存在的问题,提出了建设海峡西岸高效持续农业示范区的基本思路与技术对策 相似文献
995.
Sarah Kandrot Val Cummins Declan Jordan Jimmy Murphy 《International Journal of Green Energy》2020,17(11):687-696
ABSTRACT The imminent development of a number of offshore wind farms in the Republic of Ireland presents a sizable opportunity to stimulate the Irish economy through the growth of an indigenous and globally competitive offshore wind supply chain. This study uses a value chain analysis to evaluate the economic and employment potential of the offshore wind sector for Ireland. The analysis is based on the expenditure on products and services required to develop an offshore wind farm, the planned capacity of projects in the pipeline, and the ability of Irish companies to supply the sector. Results suggest that by 2030, 2.5–4.5GW of domestic offshore wind development could create between 11,424 and 20,563 supply chain jobs and generate between €763 m and €1.4bn in gross value added. This is the first study to estimate domestic GVA potential for the sector. 相似文献
996.
Hassan Fathabadi 《International Journal of Green Energy》2020,17(12):742-755
ABSTRACT In this paper, a novel evacuated tube solar collector (ETSC) is first designed and built. Then, the impact of adding reflector, reflector plus single-axis sun tracker and reflector plus two-axis sun tracker to the built ETSC on the thermal efficiency of the ETSC is evaluated both theoretically and experimentally. In this regard, four identical versions of the proposed ETSC have been built and utilized in four collectors built and presented in this research work. The first collector is the same proposed built ETSC, the second collector is a parabolic trough solar collector comprising one built ETSC and a reflector (ETSC+R), the third collector is composed of one built ETSC, a reflector and a single-axis sun tracker all built in this study (ETSC+R+ ST), and the fourth collector consists of one built ETSC, a reflector and a two-axis sun tracker all built in this study (ETSC+R+ DT). Theoretical basis and concepts of the four collectors are formulated and analyzed in separate subsections. Theoretical results are outlined and highlighted at the end of each subsection. Experimental measurements and data obtained from the operation of the four collectors in the four seasons are presented that point by point verify theoretical results obtained in this study. To provide a comprehensive view, a techno-economic numerical comparison is performed between the four collectors. The following points, which are also the novelty and contributions of this work, are deduced from theoretical concepts, experimental data, and comparison provided in this study: ?There is no technical and economic justification for adding a reflector to an ETSC that results in forming a parabolic trough solar collector (ETSC+R) without any sun tracker. ?There is no economic justification for adding a single-axis sun tracker to a parabolic trough solar collector (ETSC+R). ?There is no economic justification for adding a two-axis sun tracker to a parabolic trough solar collector (ETSC+R). ?Comparing between a two-axis sun tracker and a single-axis sun tracker, adding the single-axis type to a parabolic trough solar collector (ETSC+R) is more advantageous. 相似文献
997.
James W. McFarland M. Leon Hyatt 《Journal of the American Water Resources Association》1973,9(4):755-767
Alternative futures are defined to be mutually consistent alternative combinations of assumed sets of future conditions. Alternative futures are employed in conjunction with the Wollman-Bonem model to project future water use. The model solutions under different alternative futures provide an indication of the direction and relative magnitude of changes in water use, both in quantity and quality, that may result from changes in policy-influenced variables, technology, and other data. The Wollman-Bonem model is employed in this paper as a tool to illustrate the alternative futures concept. The model can best be cast as an economic model. The model solutions are not given as a set of formal projections, but as various possible water-use-over-time curves. This should aid in disspelling the erroneous idea that it is possible to make distant projections of water use as a single curve. Multiple curves suggest that water use is really a function of many variables. 相似文献
998.
Political pressures exist to increase the economic efficiency of timber management and production on the national forests
managed by the USDA Forest Service. There is growing belief both outside and within the Forest Service that current levels
of timber production, and most particularly uneconomic timber production, should be reduced. Many argue that eliminating uneconomic
timber management programs will both save money and reduce environmental degradation. This article traces the political evolution
of the focus on economic efficiency in timber production and explores the political-institutional factors that are shaping
the current policy debate. The below-cost issue is less about economic efficiency than it is about political advantage and
alternative political visions of the societal role of the nation's national forests now and in the future. 相似文献
999.
对地震保险体制改革的探索 总被引:1,自引:2,他引:1
从研究地震灾害规律和保险经营特点之间的矛盾入手,叙述地震保险经营的困难,剖析我国现行地震保险体制的缺陷,提出了建立一个新的,相对科学和合理的地震保险体制的若干建议。 相似文献
1000.
The international minerals industry continues to have a substantial investment shortfall. The widening exploration and mineral development gaps, not only in the lesser developed countries but also in the developed nations, are sowing the seeds for future mineral supply disruptions and conflicts. Mutuality of interests demands concerted initiatives, individual as well as collective, to reverse the investment trends established by international mineral finance and the multinational corporations in order to pave the way for secure mineral supplies in the future at acceptable prices. 相似文献