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671.
顶空气相色谱法测定地表水中吡啶 总被引:2,自引:0,他引:2
采用顶空进样、毛细管柱HP -INNOWAX分离、GC -FID测定地表水中吡啶。水样顶空时通过加碳酸钠盐大幅度降低了检出限 ,最低检出浓度达到 0 0 2mg/L。本法加标回收率为 96 5 %~ 10 1% ,变异系数为 7 8%~ 9 8%。 相似文献
672.
673.
674.
叙述了我国目前二氧化硫污染、酸雨危害的严重状况和开展燃煤烟气除尘脱硫技术研究的必要性,以及我国中小型燃煤锅炉烟气除尘脱硫技术的现状,提出了发展适合我国国情的中小型燃煤锅炉烟气除尘脱硫技术思路。 相似文献
675.
676.
Eduardo Soto-Galera Joel Paulo-Maya Eugenia López-López José Angel Serna-Hernández John Lyons 《Environmental management》1999,24(1):133-140
Chirostoma charari and C. compressum, and they are presumed extinct. Twelve (63%) of the remaining species had declines in distribution. Sixteen (80%) of the 20
localities sampled had lost species. The greatest declines occurred in Lago de Cuitzeo proper and in the lower portion of
the Río Grande de Morelia watershed. Species losses from the lake were attributable to drying and hypereutrophication of the
lake because of substantial reductions in the amount and quality of tributary inputs, whereas losses from the Río Grande de
Morelia watershed were the result of pollution from agricultural, municipal, and industrial sources, especially in the region
around the city of Morelia. Three localities in the upper portion of the Río Grande de Morelia watershed—Cointzio reservoir,
La Mintzita spring, and Insurgente Morelos stream—contained most of the remaining fish species diversity in the basin and
deserve additional protection. Fish faunal changes indicated major declines in the health of aquatic ecosystems in the Morelia–Cuitzeo
basin. 相似文献
677.
Validity of Performance Criteria and a Tentative Model for Regulatory Use in Compensatory Wetland Mitigation Permitting 总被引:1,自引:1,他引:0
The purpose of this paper is to develop the principles for a manageable and practical set of performance criteria that will
reasonably assure no net loss in a situation in which it cannot be absolutely assured. To this end, the performance criteria
proposed for 116 compensatory wetland projects on file with the Army Corps of Engineers in San Francisco, between 1988 and
1995, were examined. The trends discerned in the project proposals were analyzed and evaluated in light of the current state
of wetland science. Specific suggestions for the development of uniform criteria in each of four major wetland types—riparian,
perennial tidal, perennial nontidal, and seasonal—are discussed, and a system of regulation tying qualitative assessment with
quantitative requirements is outlined as a reasonable solution to the enforcement of the no-net-loss policy. 相似文献
678.
679.
Alan F. Hamlet Dennis P. Lettenmaier 《Journal of the American Water Resources Association》1999,35(6):1597-1623
ABSTRACT: As part of the National Assessment of Climate Change, the implications of future climate predictions derived from four global climate models (GCMs) were used to evaluate possible future changes to Pacific Northwest climate, the surface water response of the Columbia River basin, and the ability of the Columbia River reservoir system to meet regional water resources objectives. Two representative GCM simulations from the Hadley Centre (HC) and Max Planck Institute (MPI) were selected from a group of GCM simulations made available via the National Assessment for climate change. From these simulations, quasi-stationary, decadal mean temperature and precipitation changes were used to perturb historical records of precipitation and temperature data to create inferred conditions for 2025, 2045, and 2095. These perturbed records, which represent future climate in the experiments, were used to drive a macro-scale hydrology model of the Columbia River at 1/8 degree resolution. The altered streamflows simulated for each scenario were, in turn, used to drive a reservoir model, from which the ability of the system to meet water resources objectives was determined relative to a simulated hydrologic base case (current climate). Although the two GCM simulations showed somewhat different seasonal patterns for temperature change, in general the simulations show reasonably consistent basin average increases in temperature of about 1.8–2.1°C for 2025, and about 2.3–2.9°C for 2045. The HC simulations predict an annual average temperature increase of about 4.5°C for 2095. Changes in basin averaged winter precipitation range from -1 percent to + 20 percent for the HC and MPI scenarios, and summer precipitation is also variously affected. These changes in climate result in significant increases in winter runoff volumes due to increased winter precipitation and warmer winter temperatures, with resulting reductions in snowpack. Average March 1 basin average snow water equivalents are 75 to 85 percent of the base case for 2025, and 55 to 65 percent of the base case by 2045. By 2045 the reduced snowpack and earlier snow melt, coupled with higher evapotranspiration in early summer, would lead to earlier spring peak flows and reduced runoff volumes from April-September ranging from about 75 percent to 90 percent of the base case. Annual runoff volumes range from 85 percent to 110 percent of the base case in the simulations for 2045. These changes in streamflow create increased competition for water during the spring, summer, and early fall between non-firm energy production, irrigation, instream flow, and recreation. Flood control effectiveness is moderately reduced for most of the scenarios examined, and desirable navigation conditions on the Snake are generally enhanced or unchanged. Current levels of winter-dominated firm energy production are only significantly impacted for the MPI 2045 simulations. 相似文献
680.
完全均匀混合质量平衡水质模型在滇池中的应用 总被引:24,自引:1,他引:23
介绍了完全均匀混合假设下以质量平衡为基础的湖泊水质模型,运用滇池的实测数据对模型进行了参数率定、验证,给出了模型在滇池水质预测中的应用实测,最后讨论了模型的几个假设条件对滇池的适应性。实例研究表明,该模型可适用于滇池水质有机污染长期浓度预测。 相似文献