全文获取类型
收费全文 | 43679篇 |
免费 | 489篇 |
国内免费 | 315篇 |
专业分类
安全科学 | 1238篇 |
废物处理 | 1706篇 |
环保管理 | 5944篇 |
综合类 | 7180篇 |
基础理论 | 12483篇 |
环境理论 | 30篇 |
污染及防治 | 11119篇 |
评价与监测 | 2659篇 |
社会与环境 | 1818篇 |
灾害及防治 | 306篇 |
出版年
2022年 | 274篇 |
2021年 | 291篇 |
2019年 | 310篇 |
2018年 | 561篇 |
2017年 | 569篇 |
2016年 | 858篇 |
2015年 | 698篇 |
2014年 | 997篇 |
2013年 | 3273篇 |
2012年 | 1248篇 |
2011年 | 1812篇 |
2010年 | 1484篇 |
2009年 | 1494篇 |
2008年 | 1813篇 |
2007年 | 1903篇 |
2006年 | 1684篇 |
2005年 | 1443篇 |
2004年 | 1390篇 |
2003年 | 1367篇 |
2002年 | 1336篇 |
2001年 | 1702篇 |
2000年 | 1224篇 |
1999年 | 768篇 |
1998年 | 587篇 |
1997年 | 614篇 |
1996年 | 624篇 |
1995年 | 690篇 |
1994年 | 640篇 |
1993年 | 583篇 |
1992年 | 591篇 |
1991年 | 555篇 |
1990年 | 573篇 |
1989年 | 594篇 |
1988年 | 507篇 |
1987年 | 459篇 |
1986年 | 428篇 |
1985年 | 439篇 |
1984年 | 477篇 |
1983年 | 479篇 |
1982年 | 513篇 |
1981年 | 440篇 |
1980年 | 377篇 |
1979年 | 415篇 |
1978年 | 360篇 |
1977年 | 302篇 |
1976年 | 296篇 |
1975年 | 285篇 |
1974年 | 283篇 |
1973年 | 291篇 |
1972年 | 298篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
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
12.
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
13.
14.
We examined the impact of stressful job demands on employee attitudes and attendance. Using Karasek's (1979) theory of job decision latitude as the conceptual foundation, we hypothesized that mental and physical work demands would interact with employee beliefs of personal control. Survey data from 90 male manufacturing employees regarding their control beliefs were combined with objective job analysis data concerning mental and physical demands and one year's worth of archival data regarding unexcused absences, sick days, and days tardy. There were significant interactions between control and objective psychological demands that indicated that these demands were associated with higher levels of tardiness and sick days only under conditions of low perceived control. In contrast, subjective workload ratings showed no relationship with tardiness and sick days, but, in interaction with control, predicted work satisfaction and voluntary absence. We discussed these results in terms of a stress process that affects health-related attendance independent of employee attitudes. 相似文献
15.
New birds on the block: new neighbors increase defensive costs for territorial male willow ptarmigan 总被引:4,自引:0,他引:4
Previous researchers have hypothesized that site-faithful animals may benefit from the presence of familiar neighbors. This study compares the relative costs of territorial defense against new and former neighbors by male willow ptarmigan (Lagopus lagopus). Territorial defense against new neighbors appeared to require a greater expenditure of both time and effort than did defense against former neighbors. Territorial males that had several new neighbors spent a higher proportion of time fighting than did males with fewer new neighbors, and males with both new and former neighbors spent a greater amount of time fighting with their new neighbors, on average, than with their former neighbors. In addition, fights with new neighbors occurred relatively more frequently and were longer than fights with former neighbors. Finally, fights involving new neighbors tended to escalate to higher levels than fights between former neighbors. Reduced defensive costs for site-faithful, territorial males may provide one explanation for the tendency of males to be more site-faithful than females in many species. 相似文献
16.
M Mora R Skiles B McKinney M Paredes D Buckler D Papoulias D Klein 《Environmental pollution (Barking, Essex : 1987)》2002,116(1):169-176
Peregrine falcons (Falco peregrinus) have been recorded nesting in Big Bend National Park, Texas, USA and other areas of the Chihuahuan Desert since the early 1900s. From 1993 to 1996, peregrine falcon productivity rates were very low and coincided with periods of low rainfall. However, low productivity also was suspected to be caused by environmental contaminants. To evaluate potential impacts of contaminants on peregrine falcon populations, likely avian and bat prey species were collected during 1994 and 1997 breeding seasons in selected regions of western Texas, primarily in Big Bend National Park. Tissues of three peregrine falcons found injured or dead and feathers of one live fledgling also were analyzed. Overall, mean concentrations of DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], a metabolite of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane], were low in all prey species except for northern rough-winged swallows (Stelgidopteryx serripennis, mean = 5.1 microg/g ww). Concentrations of mercury and selenium were elevated in some species, up to 2.5 microg/g dw, and 15 microg/g dw, respectively, which upon consumption could seriously affect reproduction of top predators. DDE levels near 5 microg/g ww were detected in carcass of one peregrine falcon found dead but the cause of death was unknown. Mercury, selenium, and DDE to some extent, may be contributing to low reproductive rates of peregrine falcons in the Big Bend region. 相似文献
17.
18.
19.
20.