全文获取类型
收费全文 | 33902篇 |
免费 | 327篇 |
国内免费 | 397篇 |
专业分类
安全科学 | 977篇 |
废物处理 | 1404篇 |
环保管理 | 4613篇 |
综合类 | 5995篇 |
基础理论 | 8455篇 |
环境理论 | 15篇 |
污染及防治 | 8885篇 |
评价与监测 | 2257篇 |
社会与环境 | 1823篇 |
灾害及防治 | 202篇 |
出版年
2022年 | 294篇 |
2021年 | 301篇 |
2020年 | 193篇 |
2019年 | 263篇 |
2018年 | 487篇 |
2017年 | 488篇 |
2016年 | 766篇 |
2015年 | 550篇 |
2014年 | 822篇 |
2013年 | 2778篇 |
2012年 | 1043篇 |
2011年 | 1381篇 |
2010年 | 1151篇 |
2009年 | 1222篇 |
2008年 | 1389篇 |
2007年 | 1509篇 |
2006年 | 1333篇 |
2005年 | 1058篇 |
2004年 | 1079篇 |
2003年 | 1108篇 |
2002年 | 1006篇 |
2001年 | 1322篇 |
2000年 | 915篇 |
1999年 | 610篇 |
1998年 | 434篇 |
1997年 | 416篇 |
1996年 | 473篇 |
1995年 | 457篇 |
1994年 | 449篇 |
1993年 | 406篇 |
1992年 | 426篇 |
1991年 | 387篇 |
1990年 | 408篇 |
1989年 | 384篇 |
1988年 | 348篇 |
1987年 | 308篇 |
1986年 | 277篇 |
1985年 | 306篇 |
1984年 | 317篇 |
1983年 | 316篇 |
1982年 | 357篇 |
1981年 | 301篇 |
1980年 | 267篇 |
1979年 | 287篇 |
1978年 | 248篇 |
1977年 | 221篇 |
1976年 | 221篇 |
1975年 | 193篇 |
1974年 | 218篇 |
1973年 | 192篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
391.
392.
Kolchugina Tatyana P. Vinson Ted S. 《Mitigation and Adaptation Strategies for Global Change》1996,1(2):197-218
Several management practices are available to conserve and sequester C in the agricultural sector of the former Soviet Union (FSU). The highest rate of C accumulation would result from the implementation of a no-till management option which will only continue during the first ten years until new C equilibrium is reached. Agroforestry management options provide a longer period for C accumulation, but at a lower rate. It is possible that the longest period of C conservation may be achieved by increasing the area under perennial grasses in the crop rotation. During the first decade of implementation of the management practices, the amount of C conserved or sequestered would be approximately equal to the current rate of net C sequestration in FSU forest sector. At present, agricultural soils and vegetation of the FSU store approximately 120 Pg C; the accumulation of soil organic matter is 0.032 Pg C yr-1. The annual C loss in the FSU agricultural sector was estimated at 0.21 Pg C yr-1. 相似文献
393.
394.
395.
396.
本文主要研究了肯尼亚姆瓦彻湾(属于浅潮滩红树林湿地)泥沙交换的动力机制.该港湾属于半日潮,大、小潮的潮差分别为.2m和1.4m,大潮高水位的水面面积为17km2. 相似文献
397.
A baseline for a project consists of estimates of annual emissions of greenhouse gases (GHG) for a given time period without implementing the project. A general three-step process for determining the baseline is suggested. The emission reduction of the project is given by the difference between the baseline and the monitored annual emissions. A preferred method, direct measurement of the emission reduction, is possible for some types of projects. Methods for estimating the annual baseline emissions are not necessary for the latter category, and a definition of this project category is suggested. IPCC Guidelines for National GHG Inventories categorise the emission sources so that only direct emissions from consumption of fuel and feedstock are calculated. There are thus no emission factors for indirect emissions (e.g. electricity consumption or km transported) or emission factors that depend on technology only, independent of consumption of fuel and feedstock. Technology-dependent emission factors may thus need to be developed for estimating indirect emissions and multi-project baselines. Consistency should be sought with the IPCC Guidelines when estimating annual baseline emissions and in monitoring project emissions to ensure comparability with the National Inventories. 相似文献
398.
399.
400.