全文获取类型
收费全文 | 21631篇 |
免费 | 384篇 |
国内免费 | 439篇 |
专业分类
安全科学 | 859篇 |
废物处理 | 875篇 |
环保管理 | 3629篇 |
综合类 | 3413篇 |
基础理论 | 5602篇 |
环境理论 | 15篇 |
污染及防治 | 5445篇 |
评价与监测 | 1264篇 |
社会与环境 | 1174篇 |
灾害及防治 | 178篇 |
出版年
2023年 | 148篇 |
2022年 | 220篇 |
2021年 | 213篇 |
2020年 | 234篇 |
2019年 | 209篇 |
2018年 | 392篇 |
2017年 | 380篇 |
2016年 | 563篇 |
2015年 | 433篇 |
2014年 | 584篇 |
2013年 | 1753篇 |
2012年 | 802篇 |
2011年 | 1132篇 |
2010年 | 847篇 |
2009年 | 959篇 |
2008年 | 1041篇 |
2007年 | 1092篇 |
2006年 | 911篇 |
2005年 | 769篇 |
2004年 | 777篇 |
2003年 | 681篇 |
2002年 | 649篇 |
2001年 | 718篇 |
2000年 | 596篇 |
1999年 | 374篇 |
1998年 | 267篇 |
1997年 | 275篇 |
1996年 | 275篇 |
1995年 | 332篇 |
1994年 | 271篇 |
1993年 | 263篇 |
1992年 | 222篇 |
1991年 | 218篇 |
1990年 | 210篇 |
1989年 | 212篇 |
1988年 | 177篇 |
1987年 | 167篇 |
1986年 | 187篇 |
1985年 | 178篇 |
1984年 | 229篇 |
1983年 | 182篇 |
1982年 | 212篇 |
1981年 | 196篇 |
1980年 | 157篇 |
1979年 | 162篇 |
1978年 | 117篇 |
1977年 | 112篇 |
1975年 | 93篇 |
1974年 | 97篇 |
1972年 | 102篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Abstract: Introduction of artificial light into wildlife habitat represents a rapidly expanding form of human encroachment, particularly in coastal systems. Light pollution alters the behavior of sea turtles during nesting; therefore, long-wavelength lights—low-pressure sodium vapor and bug lights—that minimize impacts on turtles are required for beach lighting in Florida (U.S.A.). We investigated the effects of these two kinds of lights on the foraging behavior of Santa Rosa beach mice ( Peromyscus polionotus leucocephalus ). We compared patch use and giving-up densities of mice for experimental food patches established along a gradient of artificial light in the field. Mice exploited fewer food patches near both types of artificial light than in areas with little light and harvested fewer seeds within patches near bug lights. Our results show that artificial light affects the behavior of terrestrial species in coastal areas and that light pollution deserves greater consideration in conservation planning. 相似文献
3.
4.
5.
As part of a programme to characterize floating anthropogenic debris in the aquatic environment, the US Environmental Protection Agency (EPA) conducted 18 field surveys in the harbours of major metropolitan cities of the east, west, and Gulf coasts of the United States and the Mid-Atlantic Bight. the surveys were designed to provide information on the types, relative amounts, and distributions of aquatic debris in different geographic regions of the United States. Neuston nets (0.33 mm mesh) were used to collect surface debris during outgoing tides on two or three consecutive days in selected areas of each city. After each net tow, the debris, which ranged in size from small resin pellets to large plastic sheeting pieces, was identified, categorized, and counted. the data are being used to qualitatively characterize aquatic debris in coastal metropolitan areas, to examine potential regional variations, and to tentatively identify potential sources. 相似文献
6.
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
7.
Critics of the Endangered Species Act have asserted that is protects an inordinate number of subspecies and populations, in addition to full species, and that the scientific rationale for listing decisions is absent or weak. We reviewed all U.S. plants and animals proposed for listing or added to the endangered species list from 1985 through 1991 to determine the relative proportion of species, subspecies, and populations, and their rarity at time of listing. Approximately 80% of the taxa added to the list were full species, 18% were subspecies, and 2% were distinct populations segments of more widespread vertebrate species. The proportion of subspecies and populations was considerably higher among birds and mammals than among other groups. The median populations size at time of listing for vertebrate animals was 1075 individuals; for invertebrate animals it was 999. The median population size of a plant at time of listing was less than 120 individuals. Earlier listing of declining species could significantly improve the likelihood of successful recovery, and it would provide land managers and private citizens with more options for protecting vanishing plants and animals at less social or economic cost. 相似文献
8.
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
9.
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
10.