全文获取类型
收费全文 | 18708篇 |
免费 | 242篇 |
国内免费 | 158篇 |
专业分类
安全科学 | 562篇 |
废物处理 | 721篇 |
环保管理 | 3025篇 |
综合类 | 2800篇 |
基础理论 | 5008篇 |
环境理论 | 5篇 |
污染及防治 | 4788篇 |
评价与监测 | 1139篇 |
社会与环境 | 923篇 |
灾害及防治 | 137篇 |
出版年
2022年 | 130篇 |
2021年 | 150篇 |
2020年 | 119篇 |
2019年 | 176篇 |
2018年 | 271篇 |
2017年 | 262篇 |
2016年 | 408篇 |
2015年 | 288篇 |
2014年 | 402篇 |
2013年 | 1519篇 |
2012年 | 543篇 |
2011年 | 744篇 |
2010年 | 632篇 |
2009年 | 627篇 |
2008年 | 823篇 |
2007年 | 821篇 |
2006年 | 765篇 |
2005年 | 593篇 |
2004年 | 654篇 |
2003年 | 611篇 |
2002年 | 554篇 |
2001年 | 749篇 |
2000年 | 511篇 |
1999年 | 301篇 |
1998年 | 282篇 |
1997年 | 243篇 |
1996年 | 263篇 |
1995年 | 291篇 |
1994年 | 298篇 |
1993年 | 259篇 |
1992年 | 279篇 |
1991年 | 235篇 |
1990年 | 274篇 |
1989年 | 255篇 |
1988年 | 214篇 |
1987年 | 188篇 |
1986年 | 176篇 |
1985年 | 194篇 |
1984年 | 212篇 |
1983年 | 203篇 |
1982年 | 212篇 |
1981年 | 209篇 |
1980年 | 167篇 |
1979年 | 172篇 |
1978年 | 152篇 |
1977年 | 125篇 |
1975年 | 123篇 |
1974年 | 121篇 |
1973年 | 115篇 |
1972年 | 141篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
291.
292.
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
293.
R. G. Tiessen A. M. W. van Elsacker-Niele Chr. Vermeij-Keers D. Oepkes J. van Roosmalen M. C. B. Gorsira 《黑龙江环境通报》1994,14(3):173-176
A fetus with multiple structural defects was seen at prenatal ultrasound examination. After termination of the pregnancy a bilateral cleft lip, alveolus, and palate; micrognathia; and webbed joints were seen. Fetal tissues showed indications of infection, intranuclear inclusion bodies, chronic stress, haemolysis, arterial wall damage, and profuse haemorrhage. Parvovirus B19 DNA was detected in fetal tissues by dot hybridization after polymerase chain reaction. The possibility of parvovirus B19 infection leading to congenital malformations is discussed. 相似文献
294.
Wolf D. Keidel 《Die Naturwissenschaften》1992,79(8):347-357
Teil I s. Heft 7, S. 300 相似文献
295.
296.
We present a remarkable chain of events in which percutaneous umbilical cord sampling was performed in an attempt to clarify a situation of possible fetal sex chromosome mosaicism in an amniotic fluid culture and led to the discovery that the mother herself had a 45,X/46,XX/ 47.XXX chromosome constitution. This may have simply represented the chance concurrence of pseudo-mosaicism in the amniotic fluid culture of a woman with an abnormal sex chromosome constitution, but it is also possible that the 45,X colony was maternal in origin. Although clearly a most unusual circumstance, the possibility should be kept in mind when termination of a pregnancy is being considered because of apparent mosaicism in a prenatal diagnostic study. 相似文献
297.
D. Schneider 《Die Naturwissenschaften》1992,79(6):241-250
Dedicated to Prof. H. Autrum on the occasion of his 85th birthday. 相似文献
298.
299.
This paper, based on the autonomy concept, continues to investigate hierarchical forms and spatial structure of ecosystems. The former can lead to limits for the selection of the component parts of an ecosystem and a distinction between its endogenous and exogenous variables; and the latter can be lead to a hypothesis of the space of an ecosystem: the space of an ecosystem = its habitat area + supporting area + impact area, and two characteristics of ecosystems, space-overlapping and the area of ecosystem space, have been further studied referring to human activities. 相似文献
300.