全文获取类型
收费全文 | 51029篇 |
免费 | 564篇 |
国内免费 | 428篇 |
专业分类
安全科学 | 1648篇 |
废物处理 | 2193篇 |
环保管理 | 6952篇 |
综合类 | 7951篇 |
基础理论 | 13991篇 |
环境理论 | 30篇 |
污染及防治 | 12774篇 |
评价与监测 | 3272篇 |
社会与环境 | 2865篇 |
灾害及防治 | 345篇 |
出版年
2022年 | 407篇 |
2021年 | 442篇 |
2020年 | 306篇 |
2019年 | 403篇 |
2018年 | 736篇 |
2017年 | 748篇 |
2016年 | 1106篇 |
2015年 | 878篇 |
2014年 | 1320篇 |
2013年 | 4023篇 |
2012年 | 1604篇 |
2011年 | 2204篇 |
2010年 | 1816篇 |
2009年 | 1882篇 |
2008年 | 2236篇 |
2007年 | 2248篇 |
2006年 | 2049篇 |
2005年 | 1766篇 |
2004年 | 1733篇 |
2003年 | 1619篇 |
2002年 | 1592篇 |
2001年 | 1950篇 |
2000年 | 1375篇 |
1999年 | 873篇 |
1998年 | 685篇 |
1997年 | 680篇 |
1996年 | 727篇 |
1995年 | 799篇 |
1994年 | 692篇 |
1993年 | 635篇 |
1992年 | 654篇 |
1991年 | 629篇 |
1990年 | 592篇 |
1989年 | 633篇 |
1988年 | 542篇 |
1987年 | 467篇 |
1986年 | 452篇 |
1985年 | 465篇 |
1984年 | 484篇 |
1983年 | 504篇 |
1982年 | 526篇 |
1981年 | 432篇 |
1980年 | 368篇 |
1979年 | 406篇 |
1978年 | 344篇 |
1977年 | 288篇 |
1976年 | 285篇 |
1975年 | 292篇 |
1973年 | 301篇 |
1972年 | 300篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
43.
S. Kojima S. Ohta T. Yamamoto T. Miura Y. Fujiwara K. Fujikura J. Hashimoto 《Marine Biology》2002,141(1):57-64
The nucleotide sequence of part (624 bp) of a mitochondrial gene for cytochrome oxidase I was determined for 46 escarpiid vestimentiferans collected from seven sites in the western Pacific and 49 individual specimens of Arcovestia ivanovi from two sites in the Manus Basin. Phylogenetic analysis, based on the newly obtained and previously reported sequences, indicated that escarpiids in the western Pacific can be divided into two tentative species, as we proposed in a previous report. While members of the first tentative species have been collected exclusively from a seep area at a depth of 300 m off the coast of central Japan, the members of the second species inhabit some sites at depths greater than 1,100 m, namely, seep areas in Japanese and Papua-New Guinean waters as well as hydrothermal vent fields in the Okinawa Trough and the Manus Basin. We detected no genetic structure among populations of the second tentative species. The first tentative species was more closely related to a species in the eastern Pacific, Escarpia spicata, and to a species in the Gulf of Mexico, Escarpia laminata, than to the second tentative species in the western Pacific. Sequences obtained from all arcovestiids were identical with the exception of those from three individuals, each of which included a single synonymous nucleotide substitution relative to the dominant haplotype, and no genetic differences were detected between specimens from the two sites in the Manus Basin. 相似文献
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.
Quick fix. Putting out firs. Do it over. Fix it again. Bottlenecks. Come back to it later. Out of stock. Back order. Not what we ordered. Is that the best you can do? It's the contractor's fault. Not within specs. Defective. Nobody's perfect. Lost in the system. Over budget. Delayed. Late penalities. Fines. 相似文献
47.
Progress in Restoration of the Mauritius Kestrel 总被引:1,自引:0,他引:1
In the 1970s, the Mauritius Kestrel ( Falco punctatus ) was the most endangered bird of prey in the world, at one time with only two known pairs surviving in the remnant native forest of the Black River Gorges (ca. 4,000 ha). At the end of the 1991–1992 breeding season, a minimum of 30 nesting pairs and more than 170 individuals were distributed in four separate forested areas, thanks mainly to manipulation of the reproductive potential of the wild pairs, to captive propagation, and to reintroduction (restocking). Since 1984, 139 young have been reared from 618 eggs laid by captive kestrels, and 147 from 265 wild eggs incubated and hatched in the laboratory; 235 young kestrels have been released on Mauritius by hacking and fostering. Adjustments in feeding and nesting habits of kestrels hacked and released outside the Black River Gorges in areas dominated by exotic vegetation and agriculture have allowed these kestrels to survive and reproduce in an array of previously unused habitats. Now that the kestrels have been released from dependence on the remnant and dying native forest, a viable population of more than 100 nesting pairs should be achievable in a few more years. 相似文献
48.
A. L. Heathwaite 《Chemistry and Ecology》1993,8(3):217-231
Although most research has focussed on inorganic nutrient forms of nitrate (NO-3) and phosphorus (PO34) in runoff and receiving waters, nitrogen loss from agricultural land can also occur in organic and ammonium-nitrogen form; phosphorus losses, although often dominated by particulate transport, may occur in soluble organic and inorganic form. Furthermore, fluxes between different species may take place during transport from the land to the stream and as a result of in-stream, in-river or in-lake transformations. Knowledge of the spatial and temporal variation in all nitrogen species and phosphorus fractions in a drainage basin is therefore essential if the wider environmental significance of elevated nutrient concentrations in natural waters are to be assessed. This paper reviews recent work on N and P losses from agricultural land and presents some results from two intensive agricultural catchments: Slapton, Devon and the river Windrush catchment in the Cotswolds. 相似文献
49.
J. Malczewski R. Moreno-Sanchez L.A. Bojorquez-Tapia E. Ongay-Delhumeau 《Journal of Environmental Planning and Management》1997,40(3):349-374
This paper is concerned with developing a model for group decision making under multiple criteria. The multiple criteria group decision making (MCGDM)problem involves a set of feasible land use patterns that are evaluated on the basis of multiple, conflicting and noncommensurate criteria by a group of individuals. The model integrates the Analytic Hierarchy Process (AHP) and an integer mathematical programming method. The former provides a tool for structuring the decision problem and determining land suitability for different socio-economicactivities (the uses of land), the latter is used to identify the land use pattern that maximizes consensus among interest groups. The model is used to analyze environmental conflict over land resource allocation in the Cape Region of Mexico. 相似文献
50.
María L. Pignata Martha S. Cañas Hebe A. Carreras Liliana Orellana 《Environmental management》1997,21(5):793-801
Ligustrum lucidum Ait. f. tricolor (Rehd.) Rehd. in relation to atmospheric pollutants in Córdoba city, Argentina. The study area receives
regional pollutants and was categorized taking into account traffic level, industrial density, type of industry, location
of the sample point in relation to the street corner, treeless condition, and topographic level. Dried weight/fresh weight
ratio (DW/FW) and specific leaf area (SLA) were calculated, and concentrations of chlorophylls, carotenoids, total sulfur,
soluble proteins, malondialdehyde (MDA), and hydroperoxy conjugated dienes (HPCD) were determined in leaf samples. Sulfur
content correlates positively with traffic density and SLA correlates negatively with some combinations of the categorical
variables; MDA correlates positively with topographic level and total protein concentration correlates negatively with treeless
condition. On the basis of our results, traffic, location of trees, type of industry, situation of a tree with respect to
others, and topographic level are the environmental variables to bear in mind when selecting analogous sampling points in
a passive monitoring program. An approximation to predict tree injury may be obtained by measuring DW/FW ratio, proteins,
pigments, HPCD, and MDA as they are responsible for the major variability of data. 相似文献