全文获取类型
收费全文 | 11788篇 |
免费 | 141篇 |
国内免费 | 813篇 |
专业分类
安全科学 | 192篇 |
废物处理 | 898篇 |
环保管理 | 1400篇 |
综合类 | 2233篇 |
基础理论 | 3443篇 |
污染及防治 | 2431篇 |
评价与监测 | 1115篇 |
社会与环境 | 962篇 |
灾害及防治 | 68篇 |
出版年
2024年 | 2篇 |
2023年 | 38篇 |
2022年 | 150篇 |
2021年 | 152篇 |
2020年 | 96篇 |
2019年 | 70篇 |
2018年 | 1544篇 |
2017年 | 1489篇 |
2016年 | 1293篇 |
2015年 | 265篇 |
2014年 | 204篇 |
2013年 | 258篇 |
2012年 | 661篇 |
2011年 | 1521篇 |
2010年 | 826篇 |
2009年 | 736篇 |
2008年 | 1047篇 |
2007年 | 1344篇 |
2006年 | 150篇 |
2005年 | 121篇 |
2004年 | 92篇 |
2003年 | 110篇 |
2002年 | 143篇 |
2001年 | 54篇 |
2000年 | 64篇 |
1999年 | 57篇 |
1998年 | 60篇 |
1997年 | 42篇 |
1996年 | 38篇 |
1995年 | 23篇 |
1994年 | 22篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1972年 | 1篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
141.
142.
Andreas Züttel 《Mitigation and Adaptation Strategies for Global Change》2007,12(3):343-365
Hydrogen storage and transportation or distribution is closely linked together. Hydrogen can be distributed continuously in
pipelines or batch wise by ships, trucks, railway or airplanes. All batch transportation requires a storage system but also
pipelines can be used as pressure storage system. Hydrogen exhibits the highest heating value per weight of all chemical fuels.
Furthermore, hydrogen is regenerative and environment friendly. There are two reasons why hydrogen is not the major fuel of
toady’s energy consumption: First of all, hydrogen is just an energy carrier. And, although it is the most abundant element
in the universe, it has to be produced, since on earth it only occurs in the form of water. This implies that we have to pay
for this energy, which results in a difficult economic task, because since the industrialization we are used to consuming
energy for free. The second difficulty with hydrogen as an energy carrier is the low critical temperature of 33 K, i.e. hydrogen
is a gas at room temperature. For mobile and in many cases also for stationary applications the volumetric and gravimetric
density of hydrogen in a storage system is crucial. Hydrogen can be stored by six different methods and phenomena: high pressure
gas cylinders (up to 800 bar), liquid hydrogen in cryogenic tanks (at 21 K), adsorbed hydrogen on materials with a large specific
surface area (at T < 100 K), absorbed on interstitial sites in a host metal (at ambient pressure and temperature), chemically bond in covalent
and ionic compounds (at ambient pressure), oxidation of reactive metals e.g. Li, Na, Mg, Al, Zn with water. These metals easily
react with water to the corresponding hydroxide and liberate the hydrogen from the water. Finally, the metal hydroxides can
be thermally reduced to the metals in a solar furnace. 相似文献
143.
144.
145.
高频电磁辐射防护材料的研究 总被引:3,自引:0,他引:3
电磁污染已经成为一种不容忽视的全球性社会公害。因此,本文通过测量多种材料在不同高频电磁场源(即高频设备)和不同距离时对高频电磁场的屏蔽效率,获得了大量数据,并对所测数据用最小二乘法进行拟合处理,绘出了这些材料在不同高频场源下的屏蔽效果曲线。经分析,筛选出经济实用的高频近区场个人防护材料,具有推广应用的价值。 相似文献
146.
147.
148.
文中对PM10,SO2,NO2,CO四种污染因子,从时间、车流量、风力、气压、气温等方面进行影响分析,分析结果高浓度CO和NOx的污染出现在城市交通干道两侧和交通密集区域,上述四种污染园予在未来几年里仍然是环境空气中的主要污染物,危害城市人民正常生活的主要污染源,成为未来环境保护工作中的重点内容。 相似文献
149.
150.
Here we report an unequivocal arboreal coelurosaur, Epidendrosaurus ningchengensis gen. et sp. nov. This juvenile coelurosaur's third manual digit is extremely elongated, distinctively different from that of other known dinosaurs and birds. It represents certainly a type of adaptation previously unreported from the Mesozoic although the exact function of the third manual digit is unclear. The relatively long forelimb, penultimate phalanx of manual digit II, and pedal penultimate phalanges, are interpreted as evidence for the arboreal habit of Epidendrosaurus. Because Epidendrosaurus is more similar to advanced birds in some arboreal features than to Archaeopteryx, we suggest that the initial appearance of tree-adaptation in theropods was probably not directly related to flight but to other functions, such as seeking food or escaping from predators. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/s00114-002-0353-8. On that page (frame on the left side), a link takes you directly to the supplementary material. 相似文献