全文获取类型
收费全文 | 12287篇 |
免费 | 179篇 |
国内免费 | 116篇 |
专业分类
安全科学 | 403篇 |
废物处理 | 555篇 |
环保管理 | 2002篇 |
综合类 | 1439篇 |
基础理论 | 3241篇 |
环境理论 | 3篇 |
污染及防治 | 3267篇 |
评价与监测 | 852篇 |
社会与环境 | 738篇 |
灾害及防治 | 82篇 |
出版年
2022年 | 118篇 |
2021年 | 101篇 |
2020年 | 79篇 |
2019年 | 103篇 |
2018年 | 192篇 |
2017年 | 182篇 |
2016年 | 285篇 |
2015年 | 208篇 |
2014年 | 283篇 |
2013年 | 1002篇 |
2012年 | 392篇 |
2011年 | 559篇 |
2010年 | 466篇 |
2009年 | 506篇 |
2008年 | 604篇 |
2007年 | 603篇 |
2006年 | 536篇 |
2005年 | 451篇 |
2004年 | 394篇 |
2003年 | 466篇 |
2002年 | 401篇 |
2001年 | 555篇 |
2000年 | 372篇 |
1999年 | 213篇 |
1998年 | 180篇 |
1997年 | 160篇 |
1996年 | 173篇 |
1995年 | 206篇 |
1994年 | 155篇 |
1993年 | 145篇 |
1992年 | 157篇 |
1991年 | 132篇 |
1990年 | 153篇 |
1989年 | 146篇 |
1988年 | 118篇 |
1987年 | 102篇 |
1986年 | 83篇 |
1985年 | 118篇 |
1984年 | 111篇 |
1983年 | 108篇 |
1982年 | 114篇 |
1981年 | 107篇 |
1980年 | 90篇 |
1979年 | 88篇 |
1978年 | 67篇 |
1977年 | 64篇 |
1976年 | 56篇 |
1975年 | 58篇 |
1974年 | 58篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
141.
142.
In this paper we deal with the problem of identifying environmental principles for the design and operation of supply chains. The operations that are included in supply chains are briefly described along with the approaches that are applied in order to improve their environmental performance. A background of environmental principles for achieving eco-efficiency and building of environmentally friendly organizational systems is presented and emphasis is put on the application of such principles “from cradle to grave”. Then, environmental principles applicable to particular objects of logistics networks planning are identified and commented upon. In addition, selective case studies from the literature, which show the applicability of the formulated principles and their relevance to practice, are discussed. The paper concludes with some remarks regarding the benefits for companies and societies, in general, that occur as a result of the application of the formulated principles. 相似文献
143.
In Hydra vulgaris at the level of dissociated single cells endodermal cells adhere to each other more readily than to ectodermal cells at the
initial adhesion. The time required for adhesion to occur between two adjacent cells is shorter for both endodermal and ectodermal
homotypic cell adhesions once the initial adhesion of the first pair of cells has been established. It is confirmed that contact
of an aggregated pair with additional homotypic cells facilitates the occurrence of homotypic adhesions; heterotypic adhesions
are discouraged. This suggests that adhesion of homotypic cells contributes to an increased readiness for subsequent homotypic
cells to adhere.
Received: 25 August 1999 / Accepted in revised form: 11 January 2000 相似文献
144.
145.
146.
147.
148.
149.
150.
Unemployment effects of climate policy 总被引:1,自引:0,他引:1
This paper models the unemployment effects of restrictions on greenhouse gas emissions, embodying two of the most significant types of short-term economic imperfections that generate unemployment: sectoral rigidities in labor mobility and sectoral rigidities in wage adjustments. A labor policy is also analyzed that would reduce the direct negative economic effects of the emissions restrictions.The politics of limiting greenhouse gas emissions are often dominated by relatively short-term considerations. Yet the current economic modeling of emissions limitations does not embody economic features that are likely to be particularly important in the short term, in particular, the politically sensitive unemployment rate. Moreover, only a few of these studies also consider policies that would offset the negative direct economic effects of emissions restrictions. For plausible estimates of the parameters, the model shows that, with the labor market imperfections, if there were no offsetting policies, the reductions in GNP in the U.S. in the first 10 years after emissions restrictions were imposed would be as much as 4%. However, if there were two policies, instead of just one: a counteracting labor market policy, as well as the emissions restrictions, the negative direct economic effects could be completely eliminated. 相似文献