全文获取类型
收费全文 | 26305篇 |
免费 | 271篇 |
国内免费 | 220篇 |
专业分类
安全科学 | 756篇 |
废物处理 | 993篇 |
环保管理 | 3725篇 |
综合类 | 4393篇 |
基础理论 | 7063篇 |
环境理论 | 12篇 |
污染及防治 | 6696篇 |
评价与监测 | 1611篇 |
社会与环境 | 1361篇 |
灾害及防治 | 186篇 |
出版年
2022年 | 201篇 |
2021年 | 210篇 |
2020年 | 174篇 |
2019年 | 229篇 |
2018年 | 365篇 |
2017年 | 353篇 |
2016年 | 540篇 |
2015年 | 401篇 |
2014年 | 594篇 |
2013年 | 2039篇 |
2012年 | 744篇 |
2011年 | 1068篇 |
2010年 | 885篇 |
2009年 | 924篇 |
2008年 | 1108篇 |
2007年 | 1123篇 |
2006年 | 1033篇 |
2005年 | 855篇 |
2004年 | 866篇 |
2003年 | 821篇 |
2002年 | 779篇 |
2001年 | 1068篇 |
2000年 | 751篇 |
1999年 | 452篇 |
1998年 | 350篇 |
1997年 | 337篇 |
1996年 | 368篇 |
1995年 | 406篇 |
1994年 | 425篇 |
1993年 | 353篇 |
1992年 | 350篇 |
1991年 | 361篇 |
1990年 | 377篇 |
1989年 | 358篇 |
1988年 | 290篇 |
1987年 | 272篇 |
1986年 | 259篇 |
1985年 | 241篇 |
1984年 | 280篇 |
1983年 | 273篇 |
1982年 | 291篇 |
1981年 | 272篇 |
1980年 | 217篇 |
1979年 | 244篇 |
1978年 | 192篇 |
1977年 | 182篇 |
1975年 | 180篇 |
1974年 | 165篇 |
1973年 | 167篇 |
1972年 | 182篇 |
排序方式: 共有10000条查询结果,搜索用时 679 毫秒
41.
42.
To comply with EU recycling targets for packaging waste, the UK relies on an industry run and market based eco-tax levied by reprocessors on obligated businesses. After examining the details of this approach, the use of Packaging Waste Recovery Notes is assessed in terms of its allocative impact and the contribution made to eco-efficiency. The evidence indicates the UK system has minimized the cost of delivering current EU targets, but has not been able to deliver allocative efficiency or to demonstrate dynamic improvements in resource use. Its effectiveness in meeting impending higher targets remains open to question. 相似文献
43.
44.
V. Nataf M. V. Senat M. Albert L. Bidat P. de Mazancourt J. Roume L. Allard D. Le Tessier Y. Ville J. Selva 《黑龙江环境通报》2002,22(8):675-680
Male phenotype associated with a 45,X karyotype is an infrequent finding. We present a case diagnosed prenatally on amniocentesis performed for maternal age. The male phenotype was associated with a translocation of a distal part of Yp including the pseudoautosomal SHOX gene and SRY gene on the short arm of a chromosome 21. By DNA analysis we could show that the X chromosome was of maternal origin and that the breakpoint was in interval 3 of the Y chromosome. Mechanisms and genetic counselling are discussed based on a review of published cases of 45,X and XX males. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
45.
46.
47.
The brittle stars Amphiura filiformis (Müller) and Ophiura albida (Forbes) were exposed to different oxygen saturations (100, 10, 5, 3, and <1% oxygen saturation) and to physiological anoxia
(<1% oxygen saturation) at different total sulfide concentrations (0, 2, 20, 200 μM). The mortality was followed during experiments and the median survival time (LT50) was determined. The infaunal A. filiformis had a significantly higher tolerance to both hypoxia and sulfide than did the epibenthic O. albida. After exposure to 10% oxygen saturation for a month, only 2.0% A. filiformis and 0% O. albida were dead. In oxygen saturations <1% A. filiformis and O. albida had a LT50 of 7.5 and 2.5 d, respectively. The presence of even very small concentrations of sulfide decreased the survival significantly.
Sulfide is shown to be the key factor for the survival of the two species.
Received: 11 October 1996 / Accepted: 12 November 1996 相似文献
48.
Because the classification of extant and fossil articulate brachiopods is based largely upon shell characters observable in fossils, it identifies morphotaxa whose biological status can, in practice, best be inferred from estimates of genetic divergence. Allozyme polymorphism and restriction fragment length polymorphism of mitochondrial DNA (mtDNA RFLP) have been used to show that nuclear and mitochondrial genetic divergence between samples of the cancellothyridid brachiopods Terebratulina septentrionalis from Canada and T. retusa from Europe is compatible with biological speciation, but the genetic distances obtained were biased by methodological limitations. Here, we report estimates of divergence in 12S rDNA mitochondrial sequences within and between samples of these brachiopods. The sequence-based genetic distance between these samples (5.98ǂ.07% SE) is at least 10 times greater than within them and, since they also differ in a complex life-history trait, their species status is considered to be securely established. Divergence levels between 12S rDNA genes of three other cancellothyridids, T. unguicula from Alaska, T. crossei from near Japan, and Cancellothyris hedleyi from near Australia are higher than between the two North Atlantic species, and the mean nucleotide distance between all these cancellothyrids is similar to the mean distance between species of Littorina (Mollusca: Gastropoda). Sequences of both 12S and 16S genes from cancellothyridids and other short-looped brachiopod species show neither saturation nor lineage-specific rate differences and, when analysed with different outgroups, either separately or together, yield one unexpected, but well-supported, tree with Alaskan T. unguicula basal and C. hedleyi nested within Terebratulina, i.e. these genera are paraphyletic. A geologically dated divergence between Antarctic and New Zealand species of the short-looped brachiopod Liothyrella is used to calibrate the rate of 12S divergence at ca. 0.1% per million years (MY), and this rate is used to infer that T. septentrionalis and T. retusa have been diverging for ca. 60 MY and that they and T. unguicula have been diverging from their last common ancestor for ca. 100 MY. This indicates a Mesozoic origin for the present-day distribution of cancellothyridids and the basal position of T. unguicula suggests a possible North Pacific centre of origin, with separate Atlantic and Pacific radiations. The inclusion of Cancellothyris within Terebratulina also shows that adult shell characters such as umbo, foramen and symphytium shape, whilst probably indispensible for the practical classification of fossils, are not reliable guides to genealogy. 相似文献
49.
50.
Progress in the greening of UK local government has been hampered by uncertainty about the relationship between resource use and environmental protection. Ecological modernizationmay offer the most appropriateparadigm to reconcile economic, social and environmentalinterpretationsof sustainability. The transition from corporate to strategic environmental management currently being attempted by some 'green' authorities can be construed as an attempt to promote ecological modernization in the form of institutional learning. Fife Council in Scotland provides an interesting case study. Progress with corporate environmental management has become bound up with a radical devolution of decision making. Efforts to link the authority's Sustainable Development Policy to a Local Agenda 21 programme have been initiated with the piloting of sustainability indicators. 相似文献