全文获取类型
收费全文 | 48297篇 |
免费 | 7901篇 |
国内免费 | 28772篇 |
专业分类
安全科学 | 6222篇 |
废物处理 | 1379篇 |
环保管理 | 5391篇 |
综合类 | 44334篇 |
基础理论 | 9690篇 |
环境理论 | 7篇 |
污染及防治 | 10000篇 |
评价与监测 | 3504篇 |
社会与环境 | 2874篇 |
灾害及防治 | 1569篇 |
出版年
2024年 | 243篇 |
2023年 | 747篇 |
2022年 | 1926篇 |
2021年 | 2013篇 |
2020年 | 2812篇 |
2019年 | 2751篇 |
2018年 | 2978篇 |
2017年 | 3065篇 |
2016年 | 2760篇 |
2015年 | 3514篇 |
2014年 | 4176篇 |
2013年 | 5525篇 |
2012年 | 5287篇 |
2011年 | 4968篇 |
2010年 | 4594篇 |
2009年 | 4525篇 |
2008年 | 4126篇 |
2007年 | 4200篇 |
2006年 | 3523篇 |
2005年 | 2707篇 |
2004年 | 2324篇 |
2003年 | 1730篇 |
2002年 | 1555篇 |
2001年 | 1637篇 |
2000年 | 1519篇 |
1999年 | 1041篇 |
1998年 | 666篇 |
1997年 | 638篇 |
1996年 | 668篇 |
1995年 | 674篇 |
1994年 | 464篇 |
1993年 | 398篇 |
1992年 | 463篇 |
1991年 | 439篇 |
1990年 | 403篇 |
1989年 | 373篇 |
1988年 | 294篇 |
1987年 | 201篇 |
1986年 | 228篇 |
1985年 | 195篇 |
1984年 | 242篇 |
1983年 | 186篇 |
1982年 | 215篇 |
1981年 | 191篇 |
1980年 | 131篇 |
1979年 | 150篇 |
1978年 | 96篇 |
1977年 | 98篇 |
1974年 | 93篇 |
1972年 | 100篇 |
排序方式: 共有10000条查询结果,搜索用时 160 毫秒
51.
Studies on paleosols under an archaeological landmark of a rare type (a complex of kurgans with “whiskers”) dating from the Early Iron Age (the fourth century AD) have been performed in the steppe zone of the Transural Plateau. The size and shape of third-order soil polygons under stony ridges (“whiskers”) between the kurgans have been described in detail. The results have shown that the paleosol under the kurgans erected at the turn of the Late Sarmatian and Hun times (1600 years ago) is characterized by a higher humus content and deeper location of the carbonate horizon, compared to the recent soil. This indicates that an increase in atmospheric humidity took place in the fourth century AD. 相似文献
52.
T. Stoichev L. Makedonski T. Trifonova M. Stancheva F. Ribarova 《Chemistry and Ecology》2007,23(3):191-200
In spite of a worldwide reduction in the utilization of organochlorine pesticides (OCPs), they are still a problem for the aquatic environment and human health. The Black Sea is still being polluted with persistent chemicals, including OCPs. Aquatic organisms (sprat, scad, bluefish, shad, belted bonito, goby, and black mussel) with different feeding behaviours were sampled on a seasonal basis from the Bulgarian region of the Black Sea, and the concentrations of 13 OCP residues were determined. Although many of the OCPs were not detected in the samples, in all samples 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) was present mainly in the form of its metabolites 1,1-dichloro-2,2-bis(4-chlorophenyl) ethane (DDD) and 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene (DDE). Only about 12% of the total DDT was present as the parent compound pp-DDT, which suggests that it was not being used recently in the region. The total DDT concentrations were generally below 150 μg kg-1 fresh weight, but higher levels—up to 354 μg kg-1 fresh weight—were also measured for fish species with a high fat content. Between-species differences were observed, even when the concentrations were presented on a fat-level basis. DDT concentrations did not show any significant changes over the 2-yr sampling period. Fish sampled in the northern areas of the Bulgarian Black Sea coast seemed to contain higher DDT levels than those from the southern areas, suggesting a major (historical) influence of the Danube River. For permanent monitoring purposes, the utility of Black Sea gobies and scad should be considered. 相似文献
53.
54.
55.
Community evacuation following a chlorine release, Mississippi 总被引:1,自引:0,他引:1
On 7th September 1986, four miles north of Collins, Mississippi, a train transporting chlorine derailed. Two cars ruptured and gas escaped. As a result, 100 families were evacuated. To study the evacuation process, we conducted person-to-person interviews with sixty-two families staying in the evacuation center. Only 52.5% of the families received their first directive to evacuate directly from police or other officials. Delays in evacuating tended to be shorter when people were warned by the police and were told the reason for evacuating. Lack of personal transportation and preexisting health problems resulted in delays in evacuation. Concerns about evacuation included fear of looting, lack of a place to go, lack of transportation, difficulty in moving with children and elderly persons, and the need to take care of pets. One third of the interviewees reported feeling panic. Community evacuation procedures would be improved if: (1) officials contact all households directly; (2) the warning message addresses people's concerns; and (3) transportation is provided. 相似文献
56.
王爱玲 《中国安全生产科学技术》2005,1(5):76-78
从物质危险性、工艺危险性入手,评价偏二甲肼燃料库重大事故可能发生的原因、条件及其危险性等级,通过此评价对航天领域易燃、易爆、有毒危险源的危险性评价方法进行了探讨. 相似文献
57.
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
58.
59.
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
60.
中国主要电子废物产生量估算 总被引:25,自引:0,他引:25
在分析了电子废物类型及其可能造成的主要环境问题的基础上。根据电子电器产品的销量、社会保有量以及产品寿命期等因子建立模型对我国2000-2010年间的电脑、电视机、冰箱、洗衣机、空调等5大类电子电器产品的年度废弃量进行估算。结果显示到2003年电脑年度废弃量达到447万台,总体呈增长趋势;电视机、冰箱的废弃量在2003年分别达到4229万台和976万台;洗衣机年度废弃量有一定波动。大约在2005年达到一个高峰,废弃量为1521万台;空调废弃量相对于其他家电较少,但一直处于稳步增长期。并在此基础估算了我国2003年主要电子废物中的可回收资源含量。量大而且增长较快的电子废物的处置和资源再生化将是我国电子废物管理面临的一个难题。 相似文献