全文获取类型
收费全文 | 986篇 |
免费 | 118篇 |
国内免费 | 236篇 |
专业分类
安全科学 | 111篇 |
废物处理 | 47篇 |
环保管理 | 213篇 |
综合类 | 659篇 |
基础理论 | 92篇 |
污染及防治 | 124篇 |
评价与监测 | 44篇 |
社会与环境 | 37篇 |
灾害及防治 | 13篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 20篇 |
2021年 | 30篇 |
2020年 | 27篇 |
2019年 | 19篇 |
2018年 | 21篇 |
2017年 | 34篇 |
2016年 | 43篇 |
2015年 | 46篇 |
2014年 | 53篇 |
2013年 | 67篇 |
2012年 | 87篇 |
2011年 | 71篇 |
2010年 | 74篇 |
2009年 | 63篇 |
2008年 | 43篇 |
2007年 | 81篇 |
2006年 | 74篇 |
2005年 | 44篇 |
2004年 | 53篇 |
2003年 | 43篇 |
2002年 | 50篇 |
2001年 | 48篇 |
2000年 | 48篇 |
1999年 | 42篇 |
1998年 | 26篇 |
1997年 | 26篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 10篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1340条查询结果,搜索用时 515 毫秒
841.
842.
843.
844.
我国排污收费制度及其价格体系的改革 总被引:5,自引:1,他引:4
刘小呀 《中国人口.资源与环境》2003,13(1):49-53
目前,我国现行的单因子超标排污收费制度及其价格体系已不能适应现有的体制变化和日益发展的环境管理需要。本文阐述了尽快建立一个与当今市场机制相适应的、适合我国总量控制要求的多因子收费制度的重要性、迫切性与可行性,实现污染者直接承担其污染行为的全部责任;提出了制定动态、有效的收费价格体系的改革原则、构想与方法。 相似文献
845.
Wayne M. Wendland Donna Watson-Stegner 《Journal of the American Water Resources Association》1983,19(2):175-182
ABSTRACT: Cores were obtained from several tree species located both on a river floodplain and a nearby terrace. A ratio of annual tree growth on floodplains to terrace growth was developed and shown to be related to the annual river discharge. Growth ratios from the time prior to written records can therefore be used to reconstruct river discharge and infer past unrecorded flood frequency. Oak and basswood ratios yielded the best models for discharge reconstruction, whereas those of elm and birch were less useful. This method permits reconstruction of river discharge from an assemblage of growth cores obtained within a relatively small area. 相似文献
846.
Zekai Sen Abüsselam Altunkaynak 《Journal of the American Water Resources Association》2004,40(5):1189-1196
ABSTRACT: Almost all of the existing solutions of aquifer test analysis assume constant discharge rate boundary conditions. In many actual pumping tests, constant discharge cannot be maintained. This paper presents a general solution for an aquifer test with variable discharge. The exact solution of drawdown distribution around an infinitesimally small diameter well in a uniform, horizontal, extensive, homogeneous, and isotropic confined aquifer is presented when the discharge changes with time during the aquifer test period. A general equation for the type curves resulting from any discharge variability is given, and its application for the exponential changes is presented in detail. A simple straight line procedure is proposed for field applications by considering late time drawdown data. The consideration of constant discharge leads to overestimation of transmissivity but storativity is underestimated. Practical application of the discharge variability is illustrated by a field example. 相似文献
847.
B. Lane Rivenbark C. Rhett Jackson 《Journal of the American Water Resources Association》2004,40(3):639-646
ABSTRACT: Regional average evapotranspiration estimates developed by water balance techniques are frequently used to estimate average discharge in ungaged streams. However, the lower stream size range for the validity of these techniques has not been explored. Flow records were collected and evaluated for 16 small streams in the Southern Appalachians to test whether the relationship between average discharge and drainage area in streams draining less than 200 acres was consistent with that of larger basins in the size range (> 10 square miles) typically gaged by the U.S. Geological Survey (USGS). This study was designed to evaluate predictors of average discharge in small ungaged streams for regulatory purposes, since many stream regulations, as well as recommendations for best management practices, are based on measures of stream size, including average discharge. The average discharge/drainage area relationship determined from gages on large streams held true down to the perennial flow initiation point. For the southern Appalachians, basin size corresponding to perennial flow is approximately 19 acres, ranging from 11 to 32 acres. There was a strong linear relationship (R2= 0.85) between average discharge and drainage area for all streams draining between 16 and 200 acres, and the average discharge for these streams was consistent with that predicted by the USGS Unit Area Runoff Map for Georgia. Drainage area was deemed an accurate predictor of average discharge, even in very small streams. Channel morphological features, such as active channel width, cross‐sectional area, and bankfull flow predicted from Manning's equation, were not accurate predictors of average discharge. Monthly baseflow statistics also were poor predictors of average discharge. 相似文献
848.
849.
高炉煤气全干式布袋除尘净化技术 总被引:1,自引:0,他引:1
通过对国内外大中型高炉煤气除尘系统的分析比较,对高炉煤气除尘系统几个重大技术问题提出自己的见解,并指出新建、改建、扩建大中型高炉为避免重复投资,应不建湿式除尘系统备用,而向建干式布袋除尘方向发展。 相似文献
850.
根据井矿盐生产工艺特点及云应地区实际,分析了冲渣除尘水、冷却水和工艺废水循环使用的可能性,论证了云应地区制盐行业实现废水零排放的可行性,并提出了实现零排放的具体建议。 相似文献