全文获取类型
收费全文 | 37621篇 |
免费 | 473篇 |
国内免费 | 549篇 |
专业分类
安全科学 | 1113篇 |
废物处理 | 1581篇 |
环保管理 | 5067篇 |
综合类 | 6903篇 |
基础理论 | 9515篇 |
环境理论 | 15篇 |
污染及防治 | 9688篇 |
评价与监测 | 2287篇 |
社会与环境 | 2268篇 |
灾害及防治 | 206篇 |
出版年
2022年 | 348篇 |
2021年 | 322篇 |
2020年 | 283篇 |
2019年 | 286篇 |
2018年 | 548篇 |
2017年 | 526篇 |
2016年 | 820篇 |
2015年 | 638篇 |
2014年 | 901篇 |
2013年 | 2839篇 |
2012年 | 1169篇 |
2011年 | 1684篇 |
2010年 | 1305篇 |
2009年 | 1463篇 |
2008年 | 1672篇 |
2007年 | 1731篇 |
2006年 | 1484篇 |
2005年 | 1253篇 |
2004年 | 1245篇 |
2003年 | 1234篇 |
2002年 | 1152篇 |
2001年 | 1482篇 |
2000年 | 1045篇 |
1999年 | 682篇 |
1998年 | 451篇 |
1997年 | 505篇 |
1996年 | 511篇 |
1995年 | 577篇 |
1994年 | 500篇 |
1993年 | 460篇 |
1992年 | 435篇 |
1991年 | 449篇 |
1990年 | 436篇 |
1989年 | 416篇 |
1988年 | 369篇 |
1987年 | 337篇 |
1986年 | 322篇 |
1985年 | 340篇 |
1984年 | 399篇 |
1983年 | 349篇 |
1982年 | 379篇 |
1981年 | 338篇 |
1980年 | 275篇 |
1979年 | 306篇 |
1978年 | 241篇 |
1977年 | 238篇 |
1976年 | 205篇 |
1975年 | 221篇 |
1974年 | 235篇 |
1972年 | 204篇 |
排序方式: 共有10000条查询结果,搜索用时 826 毫秒
91.
Abstract: Broadly conceived and considered in its many usages, sustainability has grave defects as a planning goal, particularly when used by conservationists: it confuses means and ends; it is vague about what is being sustained and who or what is doing the sustaining; it is uninspiring; it is little more than Pinchot-era conservation (and thus ignores the many lessons learned since then); it need not be linked to land, to the land's functioning, or to any ecological science; it need not include a moral component; it is consistent with the view of humans as all-powerful manipulators of the planet; and, in general, it is such a malleable term that its popularity provides only a facade of consensus. When sustainability is defined broadly to include the full range of economic and social aspirations, it poses the particular risk that ecological and biodiversity concerns will be cast aside in favor of more pressing human wants. Given these many defects, the conservation movement should discard the term in favor of a more alluring goal, attentive to nature and its ecological functioning. A sound goal would incorporate and distill the considerable ecological and moral wisdom accumulated since Pinchot's day while giving conservationists the rhetorical tools needed to defend the land against competing pressures. In our view, conservation would be well served by an updated variant of "land health," Aldo Leopold's ecologically grounded goal from the 1940s. Land health as an independent understanding should set the essential terms of how we live and enjoy the earth, providing the framework within which we pursue our many social and economic aims. 相似文献
92.
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
93.
94.
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
95.
96.
97.
98.
Spilt notochord syndrome is an extremely rare form of spinal dysraphism characterized by a complete cleft of the spine and a persistent communication between endoderm and ectoderm. A variant of split notochord syndrome was diagnosed in a 25-week-old fetus showing a prolapsed congenital colostomy and a spinal cystic lesion. The final diagnosis included protruding colon segment, imperforate anus with a rectourethral fistula and lipomyelomeningocele. The ultrasound features of the condition and the post-natal management are discussed. The neonate was successfully treated with a posterior sagittal anorectoplasty, while the lipomyelomeningocele was resected at a later stage. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
99.
100.