全文获取类型
收费全文 | 43693篇 |
免费 | 452篇 |
国内免费 | 357篇 |
专业分类
安全科学 | 1303篇 |
废物处理 | 1977篇 |
环保管理 | 5568篇 |
综合类 | 7960篇 |
基础理论 | 10863篇 |
环境理论 | 22篇 |
污染及防治 | 10809篇 |
评价与监测 | 2994篇 |
社会与环境 | 2783篇 |
灾害及防治 | 223篇 |
出版年
2022年 | 368篇 |
2021年 | 434篇 |
2020年 | 257篇 |
2019年 | 349篇 |
2018年 | 688篇 |
2017年 | 689篇 |
2016年 | 1040篇 |
2015年 | 761篇 |
2014年 | 1173篇 |
2013年 | 3386篇 |
2012年 | 1384篇 |
2011年 | 1912篇 |
2010年 | 1518篇 |
2009年 | 1623篇 |
2008年 | 1935篇 |
2007年 | 1928篇 |
2006年 | 1712篇 |
2005年 | 1467篇 |
2004年 | 1465篇 |
2003年 | 1394篇 |
2002年 | 1301篇 |
2001年 | 1575篇 |
2000年 | 1065篇 |
1999年 | 712篇 |
1998年 | 507篇 |
1997年 | 551篇 |
1996年 | 586篇 |
1995年 | 627篇 |
1994年 | 590篇 |
1993年 | 517篇 |
1992年 | 520篇 |
1991年 | 525篇 |
1990年 | 478篇 |
1989年 | 465篇 |
1988年 | 423篇 |
1987年 | 368篇 |
1986年 | 370篇 |
1985年 | 369篇 |
1984年 | 403篇 |
1983年 | 394篇 |
1982年 | 407篇 |
1981年 | 356篇 |
1980年 | 290篇 |
1979年 | 289篇 |
1978年 | 271篇 |
1977年 | 238篇 |
1975年 | 235篇 |
1974年 | 229篇 |
1973年 | 251篇 |
1972年 | 223篇 |
排序方式: 共有10000条查询结果,搜索用时 109 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.
44.
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
45.
46.
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
47.
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
48.
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
49.
50.
From 1988 to 1991, we studied the postfledging dispersal of 31 radio-tagged White-crowned Pigeons ( Columba leucocephala ) from three natal keys in Florida Bay. Immature birds dispersed from the natal keys at 26–45 days after batching, and most young dispersed more than 20 km during the first 10 days postdispersal. Dispersing birds flew either north to the Florida mainland or east to northeast to the mainline Florida Keys. On the mainland, immature birds fed nearly exclusively within Everglades National Park or an adjacent state wildlife management area. On the mainline keys, White-crowned Pigeons selectively used 5.01–20 ha forest fragments (p < 0.10) during the first 72 hours postdispersal. After this period, dispersing birds showed no preference among fragment size classes but used deciduous seasonal forests more frequently than suburban habitat(p < 0.10). The spatial pattern of dispersal on the mainline keys suggests that, during the first 72 hours postdispersal. White-crowned Pigeons are not able to reach northern Key Largo, where 69% of the deciduous seasonal forests are protected in state or federal ownership. Protection of large forest fragments, especially on southern Key Largo, should be a priority for maintaining populations of White-crowned Pigeons. These forests provide a series of "stepping stones" that enable dispersing immature White-crowned Pigeons to fly to more distant areas where habitat availability is less restricted. This species is threatened in Florida and may play an important role in maintaining plant species diversity in the seasonal deciduous forests of south Florida by dispersing seeds of at least 37 species of trees and shrubs. Protection of sufficient habitat to allow successful postfledging dispersal of this important seed disperser will also protect the ecosystem's biodiversity. 相似文献