全文获取类型
收费全文 | 29111篇 |
免费 | 297篇 |
国内免费 | 158篇 |
专业分类
安全科学 | 672篇 |
废物处理 | 1314篇 |
环保管理 | 3391篇 |
综合类 | 4711篇 |
基础理论 | 7571篇 |
环境理论 | 16篇 |
污染及防治 | 7654篇 |
评价与监测 | 1973篇 |
社会与环境 | 2099篇 |
灾害及防治 | 165篇 |
出版年
2022年 | 293篇 |
2021年 | 318篇 |
2020年 | 178篇 |
2019年 | 217篇 |
2018年 | 463篇 |
2017年 | 462篇 |
2016年 | 709篇 |
2015年 | 471篇 |
2014年 | 817篇 |
2013年 | 2341篇 |
2012年 | 976篇 |
2011年 | 1248篇 |
2010年 | 999篇 |
2009年 | 979篇 |
2008年 | 1258篇 |
2007年 | 1347篇 |
2006年 | 1149篇 |
2005年 | 986篇 |
2004年 | 930篇 |
2003年 | 892篇 |
2002年 | 851篇 |
2001年 | 1007篇 |
2000年 | 768篇 |
1999年 | 432篇 |
1998年 | 321篇 |
1997年 | 344篇 |
1996年 | 331篇 |
1995年 | 408篇 |
1994年 | 366篇 |
1993年 | 334篇 |
1992年 | 328篇 |
1991年 | 323篇 |
1990年 | 362篇 |
1989年 | 324篇 |
1988年 | 279篇 |
1987年 | 273篇 |
1986年 | 257篇 |
1985年 | 244篇 |
1984年 | 293篇 |
1983年 | 242篇 |
1982年 | 307篇 |
1981年 | 245篇 |
1980年 | 221篇 |
1979年 | 236篇 |
1978年 | 208篇 |
1977年 | 182篇 |
1974年 | 182篇 |
1973年 | 188篇 |
1972年 | 180篇 |
1971年 | 171篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
71.
The situation and the latest findings of forest damage research in Germany are discussed. A newly developed concept for this research is described. This concept allows to identify the drawbacks of the recent damage research concept but also the integration of results compiled up to now. The importance for including natural occurring stress factors such as climate, soil conditions or local situation of individual species is outlined. 相似文献
72.
73.
When combined in the lining and covering of waste-containment facilities, soil and geosynthetic components protect the environment by acting as a hydraulic barrier. Equipment loading may significantly increase the tensile stress induced in geosynthetic components, leading to a potential stability problem. Large equipment loadings may also result in a localized circular slip surface during construction operations. New analytical method based on discrete element modelling is proposed for estimating the distribution of tensile force developed in the individual geosynthetic components of the lining system and for evaluating the safety factor of slope failure due to equipment loading. The analytical results of an example are presented to demonstrate the applicability of the analytical method for the lining system of a waste landfill. The analyses of the example show that equipment loading provide a substantial increase in the tensile forces of the geosynthetic components of a lining system and that the possibility of shallow failure due to equipment loading increases as the slope becomes steeper. This method is a useful tool for analysing the lining system of waste landfills with complex lining components. 相似文献
74.
5p deletion syndrome commonly known as cri du chat is well described in affected neonates with catlike cry and hypotonia. Karyotyping will usually show a deletion of the short arm of one chromosome 5 with variable breakpoints. Only a few cases have been reported prenatally, and the fetal form of the syndrome has not been clearly individualised. We report a new case of 5p deletion syndrome diagnosed prenatally in association with Dandy–Walker syndrome and agenesis of the corpus callosum. Other brain anomalies have been reported previously, but this unusual association suggests the use of a specific probe in the investigation of these malformations. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
75.
New data on the composition of surface assemblages of plant macroremains from soil and swamp samples have been obtained in the study of geomorphologically different localities in the middle reaches of the Nizhnyaya Tunguska River. The results of paleocarpological analysis of forest soil sections supported by relevant palynological and geochronological data are presented. Natural changes of the forest cover over the past 2400 years and quantitative characteristics of the paleoclimate during each stage are described.Translated from Ekologiya, No. 1, 2005, pp. 3–10.Original Russian Text Copyright © 2005 by Koshkarova, Koshkarov. 相似文献
76.
A. Coulomb L'Herminé A. Aboura S. Brisset L. Cuisset V. Castaigne P. Labrune R. Frydman Dr G. Tachdjian 《黑龙江环境通报》2003,23(11):938-943
Prader–Willi syndrome (PWS) results from either paternal deletion of 15q11–q13, or maternal uniparental disomy (UPD) of chromosome 15 or imprinting center mutation. Prenatal diagnosis of PWS is currently indicated for chromosomal parental translocation involving chromosome 15 and for decreased fetal movements during the third trimester of gestation. Here we present the prenatal diagnosis of PWS during the first trimester of gestation and autopsy findings. Chorionic villus sampling (CVS) was performed for advanced maternal age at 13 weeks' gestation. CVS showed mosaicism including cells with a normal karyotype and cells with trisomy 15. Amniocentesis showed cells with a normal karyotype. Molecular analysis demonstrated that the fetus had a typical PWS abnormal methylation profile and maternal disomy for chromosome 15. Fetal ultrasound examination showed slightly enlarged lateral ventricles and hypoplasic male external genitalia without intra-uterine growth retardation. The autopsy showed a eutrophic male fetus with facial dysmorphy, hypoplasic genitalia, abnormal position of both feet and posterior hypoplasia of the corpus callosum. This report points out that in a karyotypically normal fetus with ambiguous male external genitalia and cerebral anomalies, extensive cytogenetic and molecular biology studies are strongly recommended because of risk of PWS. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
77.
M. Marcelli M. Caburazzi A. Perilli V. Piermattei E. Fresi 《Chemistry and Ecology》2005,21(5):351-367
The towed undulating vehicle (TUV), named SARAGO, was used for two fine-scale surveys between the Italian and the Sardinian coasts during the Astraea 2 cruise (6-7 and 26-27 September 1995), studying the deep chlorophyll maximum distribution. SARAGO sections identify a sub-surface doming with higher chlorophyll a and primary production concentrations in the upwelling area of a cyclonic gyre region, detected by sea-surface temperature images. In the first section, the cyclone presents a double doming, in density and salinity, with shallower and concentrated patches of chlorophyll a for about 2 miles. Twenty days later, the second section shows that the gyre changes shape and extension, showing a single doming with higher primary production and chlorophyll a concentrations, distributed over a large area of about 40 nautical miles. SARAGO allows analysis of this high-variability phenomenon (cyclonic gyre) and allows concentrated patches (2 nm) to be identified, thus proving the importance of TUVs in the study of mesoscale processes. 相似文献
78.
79.
80.
Earthquake hazard assessment after Mexico (1985) 总被引:1,自引:0,他引:1
Degg MR 《Disasters》1989,13(3):237-246
The 1985 Mexican earthquake ranks foremost amongst the major earthquake disasters of the twentieth century. One of the few positive aspects of the disaster is that it provided massive quantities of data that would otherwise have been unobtainable. Every opportunity should be taken to incorporate the findings from these data in earthquake hazard assessments. The purpose of this paper is to provide a succinct summary of some of the more important lessons from Mexico. It stems from detailed field investigations, and subsequent analyses, conducted by the author on the behalf of reinsurance companies. 相似文献