全文获取类型
收费全文 | 20789篇 |
免费 | 144篇 |
国内免费 | 117篇 |
专业分类
安全科学 | 333篇 |
废物处理 | 900篇 |
环保管理 | 2549篇 |
综合类 | 4087篇 |
基础理论 | 5428篇 |
环境理论 | 6篇 |
污染及防治 | 4527篇 |
评价与监测 | 1395篇 |
社会与环境 | 1779篇 |
灾害及防治 | 46篇 |
出版年
2022年 | 109篇 |
2021年 | 122篇 |
2019年 | 101篇 |
2018年 | 733篇 |
2017年 | 690篇 |
2016年 | 712篇 |
2015年 | 283篇 |
2014年 | 363篇 |
2013年 | 1080篇 |
2012年 | 605篇 |
2011年 | 1305篇 |
2010年 | 856篇 |
2009年 | 973篇 |
2008年 | 1210篇 |
2007年 | 1456篇 |
2006年 | 601篇 |
2005年 | 572篇 |
2004年 | 555篇 |
2003年 | 612篇 |
2002年 | 606篇 |
2001年 | 629篇 |
2000年 | 400篇 |
1999年 | 296篇 |
1998年 | 204篇 |
1997年 | 203篇 |
1996年 | 221篇 |
1995年 | 230篇 |
1994年 | 230篇 |
1993年 | 216篇 |
1992年 | 195篇 |
1991年 | 205篇 |
1990年 | 196篇 |
1989年 | 169篇 |
1988年 | 168篇 |
1987年 | 154篇 |
1986年 | 153篇 |
1985年 | 148篇 |
1984年 | 180篇 |
1983年 | 170篇 |
1982年 | 172篇 |
1981年 | 144篇 |
1980年 | 132篇 |
1979年 | 123篇 |
1978年 | 134篇 |
1977年 | 115篇 |
1976年 | 103篇 |
1975年 | 107篇 |
1974年 | 118篇 |
1971年 | 98篇 |
1967年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
251.
252.
253.
Pesticide use in agriculture can cause undesirable effects on humans and the natural environment. One of the objectives of integrated agriculture is the elimination or reduction of possible sources of environmental pollution such as pesticides. To achieve this objective, farmers need a method to assist them in estimating the environmental impact of pesticide use. This paper addresses a two-part question: what factors should be taken into consideration to assess pesticide environmental impact, and how can impact be quantified? As the environmental impact of a pesticide depends on its dispersion in the environment and on its toxicological properties, the literature on these topics is reviewed to address the first part of the question. To address the second part of the question, six recent approaches to assess the impact of pesticides on the environment are compared regarding choice, transformation and aggregation of input parameters. The use of simulation models to assess environmental impact is discussed. 相似文献
254.
255.
256.
257.
258.
Mitigation and adaptation synergy in forest sector 总被引:1,自引:1,他引:1
N. H. Ravindranath 《Mitigation and Adaptation Strategies for Global Change》2007,12(5):843-853
Mitigation and adaptation are the two main strategies to address climate change. Mitigation and adaptation have been considered
separately in the global negotiations as well as literature. There is a realization on the need to explore and promote synergy
between mitigation and adaptation while addressing climate change. In this paper, an attempt is made to explore the synergy
between mitigation and adaptation by considering forest sector, which on the one hand is projected to be adversely impacted
under the projected climate change scenarios and on the other provide opportunities to mitigate climate change. Thus, the
potential and need for incorporating adaptation strategies and practices in mitigation projects is presented with a few examples.
Firstly, there is a need to ensure that mitigation programs or projects do not increase the vulnerability of forest ecosystems
and plantations. Secondly, several adaptation practices could be incorporated into mitigation projects to reduce vulnerability.
Further, many of the mitigation projects indeed reduce vulnerability and promote adaptation, for example; forest and biodiversity
conservation, protected area management and sustainable forestry. Also, many adaptation options such as urban forestry, soil
and water conservation and drought resistant varieties also contribute to mitigation of climate change. Thus, there is need
for research and field demonstration of synergy between mitigation and adaptation, so that the cost of addressing climate
change impacts can be reduced and co-benefits increased. 相似文献
259.
260.
G.L. Feng J. Letey A.C. Chang M. Campbell Mathews 《Agriculture, ecosystems & environment》2005,110(3-4):219-229
Large scale dairy operations are common. In many cases the manure is deposited on a paved surface and then removed with a flushing system, after which the solids are separated, the liquid stored in ponds, and eventually the liquid applied on adjacent crop land. Management of liquid manure to maximize the fertilizer value and minimize water quality degradation requires knowledge of the interactive effects of mineralization of organic N (ON) to NH4+, crop uptake of mineral N, and leaching of NO3− on a temporal basis. The purpose of the research was to use the ENVIRO-GRO model to simulate how the amount of applied N, timing of N application, ON mineralization rates, chemical form of N applied, and irrigation uniformity affected (1) yields of corn (Zea mays) in summer and a forage grass in winter in a Mediterranean climate and (2) the amount of NO3− leached below the root zone. This management practice is typical for dairies in the San Joaquin Valley of California. The simulations were conducted for a 10-year period. Steady state conditions, whereby an equivalent amount of N applied in the organic form will be mineralized in a given year, are achieved more rapidly for materials with high mineralization rates. Both timing and total quantity of N application are important in affecting crop yield and potential N leaching. Major conclusions from the simulations are as follows. Frequent low applications are preferred to less frequent higher applications. Increasing the amount of N application increased both the crop yield and the amount of NO3− leached. Increasing irrigation uniformity increased crop yields but had variable effects on the amount of NO3− leached. A winter forage crop following a summer corn crop effectively reduced the leaching of residual soil N following the corn crop. 相似文献