全文获取类型
收费全文 | 359篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 30篇 |
废物处理 | 14篇 |
环保管理 | 100篇 |
综合类 | 28篇 |
基础理论 | 83篇 |
环境理论 | 1篇 |
污染及防治 | 67篇 |
评价与监测 | 27篇 |
社会与环境 | 9篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 40篇 |
2012年 | 11篇 |
2011年 | 22篇 |
2010年 | 12篇 |
2009年 | 16篇 |
2008年 | 13篇 |
2007年 | 12篇 |
2006年 | 20篇 |
2005年 | 10篇 |
2004年 | 18篇 |
2003年 | 11篇 |
2002年 | 15篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1980年 | 4篇 |
1978年 | 3篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有361条查询结果,搜索用时 15 毫秒
351.
Diana F. Tomback Jane Kees Clary James Koehler Raymond J. Hoff Stephen F. Arno 《Conservation biology》1995,9(3):654-664
In the northern Rocky Mountains, whitebark pine ( Pinus albicaulis ) is rapidly declining as a result of previous fire exclusion policies, mountain pine beetle ( Dendroctonus ponderosae ) outbreaks, and white pine blister rust ( Cronartium ribicola ). Blister rust is potentially the most destructive agent, killing seedlings, cone-bearing branches, and, eventually, mature trees. We examined densities of whitebark pine regeneration and the incidence and severity of blister-rust infection of seedlings and saplings in the 25-year-old Sundance Burn in the Selkirk Range of northern Idaho, an area heavily infected by blister rust. We found that the mean regeneration density of whitebark pine was significantly lower than that of two other comparably aged burns in western Montana. The low density was attributed to the severe damage to the seed source on the burn perimeter, resulting from previous infestation of mountain pine beetle and blister rust. Overall, 29% of the whitebark pine regeneration in the Sundance Burn was infected by blister rust. Age and height of seedlings were important predictors of incidence of infection, and height was the most important predictor of severity of infection. Thus, as seedlings grow larger, they present a bigger target to airborne blister-rust spores. Because of the lack of seed production in the adjacent forest and expected mortality, regeneration of whitebark pine in the Sundance Burn will be slow. In areas of northern Idaho and northwestern Montana affected by blister rust and pine beetle, prescribed fires for managing whitebark pine ecosystems should be restricted to small areas or should require plantings of rust-resistant seedlings. 相似文献
352.
353.
Firm incentives to promote technological change in pollution control 总被引:17,自引:0,他引:17
The process of technological change in pollution control is broken into three basic steps: innovation, diffusion, and optimal agency response. Firm incentives to promote these steps are then examined under five regulatory regimes: direct controls, emission subsidies, emission taxes, free marketable permits, and auctioned marketable permits. On a relative basis, emission taxes and auctioned permits provide the highest firm incentives to promote technological change; at times, free permits generate lower incentives. Direct controls, which are common regulatory tools, usually provide the lowest relative firm incentives to promote technological change. 相似文献
354.
355.
356.
Enrique Castillo Gabor M. Karadi Raymond J. Krizek 《Journal of the American Water Resources Association》1972,8(2):266-281
The two-dimensional, steady-state, unconfined flow of a homogeneous fluid through jointed rock is studied for both laminar and turbulent conditions by use of a method which is based on previously developed theoretical and experimental flow relationships. However, only the independent unknowns are selected in order to reduce the complexity of the problem and render it more readily tractable. The intact rock is assumed to be impermeable, and two intersecting systems of plane, parallel joints are used in the mathematical model, taking into account the surface roughness of the joints. The mathematical solution of the resulting nonlinear (due to turbulent flow in some joints) system of equations is obtained by use of a rapidly converging iterative procedure, wherein each iteration takes special advantage of the banded nature of the associated matrix. For the particular case where a free surface exists, the general flow equations are not satisfied, because some of the joints in the vicinity of the free surface do not flow full; therefore, new equations must be established to handle this condition. Once the development of the mathematical model is accomplished, several cases involving different geometric characteristics (width, orientation, and roughness of joints) are solved for a rectangular domain, and graphs are given to illustrate the influence of the various parameters on the manifested flow behavior. 相似文献
357.
Donald S. Cherry Rufus K. Guthrie Ernst M. Davis Raymond S. Harvey 《Journal of the American Water Resources Association》1984,20(4):535-544
ABSTRACT Coal ash effluent effects including particulates, acidic pH excursions, elemental concentrations and bioconcentration in selected organisms have been studied as changes in water quality and densities of benthic macroinvertebrate and mosquitofish (Gambusia affinis) populations in a swamp drainage system over an eight-year period. Three changes in the ash basin settling system were made between mid- 1973 and January 1982. Initial density of the aquatic biota was altered severely by heavy ash siltation, followed by acidic pH excursions and perhaps overall by elemental concentrations and bioaccumulation. Heavy ash siltation, followed by acidic Ph excursions (mean of 5.5, extreme of 3.5) after the addition of fly ash to the original settling basin system, had the most profound effect on biota. Dipterans (chironomids) and some odonates (Plathemis lydia and Libellula spp.) were resistant to heavy ash siltation, while mosquitofish, which showed no discernible responses to ash siltation, were absent at acidic pH, along with the few previously surviving invertebrate populations. Elemental concentrations of arsenic, cadmium, chromium, copper, selenium, and zinc did not appear to limit aquatic flora and fauna on a short-term, acute basis. Long, chronic elemental exposures may have been instrumental in retarding the recovery of all forms of aquatic life in the receiving system. Elemental concentrations (except for arsenic and selenium) in the receiving system were generally one to two orders of magnitude higher than the Water Quality Criteria set by the U.S. Environmental Protection Agency (1980) for protection of aquatic life for the minimum and 24-hour mean values. From collective elemental exposures in the receiving system, bioconcentration factors in macrophytes, invertebrates and fish were generally lower than those reported in the literature for laboratory, single elemental concentrations. By 1978, when the new settling basin systems were operating effectively, invertebrate populations were largely recovered, and mosquitofish populations recovered within one year afterward. 相似文献
358.
Sivak M Luoma J Flannagan MJ Bingham CR Eby DW Shope JT 《Journal of Safety Research》2007,38(3):337-355
INTRODUCTION: This article examines five major road-safety risk factors: exceeding posted speed limits, not using safety belts, driving while intoxicated, nighttime driving, and young drivers. METHOD: The importance of each of these factors is documented, known effective countermeasures (both policy and technology based) are discussed, and impediments to the implementation of these countermeasures in the United States are examined. RESULTS: Based on current understanding of the five major risk factors, and of the available countermeasures, there appear to be a variety of opportunities to make substantial gains in road safety using existing knowledge. The limited implementation of a variety of known countermeasures therefore appears to be inconsistent with high-level, strategic goals to improve road safety. Consequently, a recommendation is made to comprehensively re-examine the balance between the countermeasures discussed in this article and economic, mobility, and privacy concerns. IMPACT ON PUBLIC SAFETY: Such a re-examination is likely to result in broad support for these countermeasures, with a consequent major improvement in road safety. 相似文献
359.
Tognetti Arnaud Ganem Guila Raymond Michel Faurie Charlotte 《Behavioral ecology and sociobiology》2018,72(9):1-10
Behavioral Ecology and Sociobiology - Members of a social group must behave similarly for a group to persist. One way for this behavioural similarity to occur is through the contagious spread of... 相似文献
360.
Jing Ding Wanyi Seow Jizhong Zhou Raymond Jianxiong Zeng Jun Gu Yan Zhou 《Frontiers of Environmental Science & Engineering》2021,15(1):7