全文获取类型
收费全文 | 9828篇 |
免费 | 857篇 |
国内免费 | 2591篇 |
专业分类
安全科学 | 393篇 |
废物处理 | 186篇 |
环保管理 | 1961篇 |
综合类 | 7177篇 |
基础理论 | 1165篇 |
环境理论 | 6篇 |
污染及防治 | 778篇 |
评价与监测 | 1137篇 |
社会与环境 | 416篇 |
灾害及防治 | 57篇 |
出版年
2024年 | 64篇 |
2023年 | 226篇 |
2022年 | 334篇 |
2021年 | 413篇 |
2020年 | 426篇 |
2019年 | 371篇 |
2018年 | 306篇 |
2017年 | 400篇 |
2016年 | 423篇 |
2015年 | 505篇 |
2014年 | 534篇 |
2013年 | 715篇 |
2012年 | 672篇 |
2011年 | 744篇 |
2010年 | 610篇 |
2009年 | 576篇 |
2008年 | 478篇 |
2007年 | 657篇 |
2006年 | 665篇 |
2005年 | 499篇 |
2004年 | 435篇 |
2003年 | 503篇 |
2002年 | 421篇 |
2001年 | 383篇 |
2000年 | 357篇 |
1999年 | 278篇 |
1998年 | 201篇 |
1997年 | 178篇 |
1996年 | 156篇 |
1995年 | 114篇 |
1994年 | 120篇 |
1993年 | 77篇 |
1992年 | 72篇 |
1991年 | 60篇 |
1990年 | 42篇 |
1989年 | 22篇 |
1988年 | 13篇 |
1987年 | 29篇 |
1986年 | 20篇 |
1985年 | 17篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 19篇 |
1977年 | 9篇 |
1975年 | 7篇 |
1973年 | 13篇 |
1972年 | 15篇 |
1971年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 734 毫秒
741.
742.
743.
744.
745.
Kevin G. Boggs Robert W. Van Kirk Gary S. Johnson Jerry P. Fairley P. Steve Porter 《Journal of the American Water Resources Association》2010,46(6):1116-1132
Boggs, Kevin G., Robert W. Van Kirk, Gary S. Johnson, Jerry P. Fairley, and P. Steve Porter, 2010. Analytical Solutions to the Linearized Boussinesq Equation for Assessing the Effects of Recharge on Aquifer Discharge. Journal of the American Water Resources Association (JAWRA) 46(6):1116–1132. DOI: 10.1111/j.1752-1688.2010.00479.x Abstract: There is a need to develop a general understanding of how variations in aquifer recharge are reflected in discharge. Analytical solutions to the linearized Boussinesq equation governing flow in an unconfined aquifer provide a unified mathematical framework to quantify relationships among lag time, attenuation and distance between aquifer recharge and discharge and the effect of an up-gradient no-flow boundary. We applied this framework to three types of recharge: (1) instantaneous, (2) periodic, and (3) constant rate for a finite duration. When the temporal scale of recharge exceeds the diffusive aquifer time scale, recharge will be reflected in discharge quickly and with little attenuation. When aquifer time scale is large, most recharge events are shorter in scale than that of the aquifer, resulting in large attenuation. Attenuation is more sensitive to boundary effects than lag time, and boundary effects increase as recharge time scale increases. Boundary effects can often be ignored when the recharge source is farther than 1/3 of the domain length away from the no-flow boundary. We illustrate analytical results with application to the economically critical Eastern Snake River Plain Aquifer in Idaho. In this aquifer, detectable annual and decadal cycles in discharge can result from recharge no farther than 20 and 60 km away from the discharge point, respectively. The effects of more distant, long-term recharge can be detected only after a time lag of several decades. 相似文献
746.
Scott M. Payne William W. Woessner 《Journal of the American Water Resources Association》2010,46(5):1003-1023
Payne, Scott M. and William W. Woessner, 2010. An Aquifer Classification System and Geographical Information System-Based Analysis Tool for Watershed Managers in the Western U.S. Journal of the American Water Resources Association (JAWRA) 46(5):1003-1023. DOI: 10.1111/j.1752-1688.2010.00472.x Abstract: Aquifers and groundwater systems can be classified using a variety of independent methods to characterize geologic and hydraulic properties, the degree of connection with surface water, and geochemical conditions. In light of a growing global demand for water, an approach for classifying groundwater systems at the watershed scale is needed. A comprehensive classification system is proposed that combines recognized methods and new approaches. The purpose of classification is to provide groundwater professionals, policy makers, and watershed managers with a widely applicable and repeatable system that reduces sometimes cumbersome complex databases and analyzes to straightforward terminology and graphical representations. The proposed classification system uses basin geology, aquifer productivity, water quality, and the degree of groundwater/surface water connection as classification criteria. The approach is based on literature values, reference databases, and fundamental hydrologic and hydrogeologic principles. The proposed classification system treats dataset completeness as a variable and includes a tiered assessment protocol that depends on the quality and quantity of data. In addition, it assembles and catalogs groundwater information using a consistent set of nomenclature. It is designed to analyze and display results using Geographical Information System mapping tools. 相似文献
747.
Yu-Pin Lin Bai-You Cheng Tsun-Kuo Chang 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):235-244
This study identifies the natural background, anthropogenic background and distribution of contamination caused by heavy metal pollutants in soil in Chunghua County of central Taiwan by using a finite mixture distribution model (FMDM). The probabilities of contaminated area distribution are mapped using single-variable indicator kriging and multiple-variable indicator kriging (MVIK) with the FMDM cut-off values and regulation thresholds for heavy metals. FMDM results indicate that Cr, Cu, Ni and Zn can be individually fitted by a mixture model representing the background and contamination distributions of the four metals in soil. The FMDM cut-off values for contamination caused by the metals are close to the regulation thresholds, except for the cut-off value of Zn. The receiver operating characteristic (ROC) curve validates that indicator kriging and MVIK with FMDM cut-off values can reliably delineate heavy metals contamination, particularly for areas lacking background information and high heavy metal concentrations in soil. 相似文献
748.
Amvrossios C. Bagtzoglou Eric D. Kenney April Hiscox David R. Miller 《Environmental Forensics》2014,15(2):147-158
This work applies optimization and an Eulerian inversion approach presented by Bagtzoglou and Baun in 2005 in order to reconstruct contaminant plume time histories and to identify the likely source of atmospheric contamination using data from a real test site for the first time. Present-day distribution of an atmospheric contaminant plume as well as data points reflecting the plume history allow the reconstruction and provide the plume velocity, distribution, and probable source. The method was tested to a hypothetical case and with data from the Forest Atmosphere Transfer and Storage (FACTS) experiment in the Duke experimental forest site. In the scenarios presented herein, as well as in numerous cases tested for verification purposes, the model conserved mass, successfully located the peak of the plume, and managed to capture the motion of the plume well but underestimated the contaminant peak. 相似文献
749.
Isotopic measurements of the 34 m3/s discharge from the Fall River Springs of northern California indicate recharge from 50 km upgradient in high elevation regions of Medicine Lake Volcano. Age determinations suggest less than 20-year travel time. Data demonstrate Klamath Basin further north cannot be a recharge source. Mass balance calculations support that annual precipitation on the volcano supplies observed spring discharge, requiring 50%–75% recharge rates. Radiocarbon and δ13C of dissolved inorganic carbon indicate 30%–40% is derived from magmatic CO2. Measured excess 3He is also consistent with the presence of magmatic gas derived from the Quaternary Age Medicine Lake Volcano. 相似文献
750.
简述了炼油装置区恶臭污染源的主要分布、恶臭气体组成和排放规律,介绍了恶臭治理的基本方法。通过治理实例,重点分析了目前常用的吸收法、燃烧法、生物法和吸附法等恶臭治理技术的优势和相对不足,并对恶臭治理应用技术方案的选择提出建议。 相似文献