全文获取类型
收费全文 | 32219篇 |
免费 | 402篇 |
国内免费 | 426篇 |
专业分类
安全科学 | 1026篇 |
废物处理 | 1299篇 |
环保管理 | 4377篇 |
综合类 | 5440篇 |
基础理论 | 8196篇 |
环境理论 | 17篇 |
污染及防治 | 8144篇 |
评价与监测 | 1998篇 |
社会与环境 | 2323篇 |
灾害及防治 | 227篇 |
出版年
2022年 | 290篇 |
2021年 | 304篇 |
2020年 | 271篇 |
2019年 | 264篇 |
2018年 | 498篇 |
2017年 | 484篇 |
2016年 | 703篇 |
2015年 | 560篇 |
2014年 | 841篇 |
2013年 | 2543篇 |
2012年 | 1067篇 |
2011年 | 1507篇 |
2010年 | 1184篇 |
2009年 | 1325篇 |
2008年 | 1482篇 |
2007年 | 1540篇 |
2006年 | 1293篇 |
2005年 | 1119篇 |
2004年 | 1082篇 |
2003年 | 1041篇 |
2002年 | 974篇 |
2001年 | 1201篇 |
2000年 | 937篇 |
1999年 | 564篇 |
1998年 | 385篇 |
1997年 | 417篇 |
1996年 | 404篇 |
1995年 | 483篇 |
1994年 | 432篇 |
1993年 | 381篇 |
1992年 | 334篇 |
1991年 | 370篇 |
1990年 | 364篇 |
1989年 | 355篇 |
1988年 | 284篇 |
1987年 | 251篇 |
1986年 | 290篇 |
1985年 | 260篇 |
1984年 | 317篇 |
1983年 | 259篇 |
1982年 | 300篇 |
1981年 | 269篇 |
1980年 | 249篇 |
1979年 | 279篇 |
1978年 | 176篇 |
1977年 | 189篇 |
1975年 | 180篇 |
1974年 | 168篇 |
1973年 | 172篇 |
1972年 | 181篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
A. V. Krylov 《Russian Journal of Ecology》2004,35(5):316-323
The abundance and trophic structure of zooplankton along the longitudinal profile of two typical rivers in the Yaroslavl sector of the Volga region are determined by anthropogenic and zoogenic factors. The distribution of zooplankton under the influence of these factors is described by the concept of patch dynamics. The abundance of zooplankton reaches the highest values in the ameliorated upper reaches of rivers and in beaver ponds. 相似文献
43.
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
44.
David L. Skidmore Aditya P. Pai Ants Toi Leslie Steele David Chitayat 《黑龙江环境通报》2003,23(12):1009-1013
Two de novo cases with Apert Syndrome detected prenatally are presented herein. In the first, fetal ultrasound findings of syndactyly of the hands, craniosynostosis and proptosis resulted in a prenatal diagnosis in the nineteenth week of gestation. This is the earliest prenatal diagnosis of this syndrome in a not-at-risk case. Following counseling, this pregnancy was terminated and subsequent pathological examination and DNA analysis confirmed the diagnosis of Apert Syndrome and coarctation of the aorta. In the second case, fetal ultrasound at 21 weeks' gestation revealed a hypoplastic left heart and clover-leaf skull. Following counseling, this pregnancy was also terminated. Further examination of the fetus and DNA analysis led to a diagnosis of Apert Syndrome. These cases emphasize the need to complete a thorough fetal ultrasound in cases with potentially lethal cardiac abnormality and the importance of incorporating a fetal pathologist, as well as a medical geneticist, in the investigations performed after delivery or pregnancy termination when a fetal abnormality is detected on ultrasound. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
45.
46.
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
47.
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
48.
49.
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
50.
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