全文获取类型
收费全文 | 12236篇 |
免费 | 1063篇 |
国内免费 | 4757篇 |
专业分类
安全科学 | 734篇 |
废物处理 | 1269篇 |
环保管理 | 1552篇 |
综合类 | 9691篇 |
基础理论 | 1390篇 |
环境理论 | 1篇 |
污染及防治 | 2874篇 |
评价与监测 | 390篇 |
社会与环境 | 128篇 |
灾害及防治 | 27篇 |
出版年
2024年 | 14篇 |
2023年 | 115篇 |
2022年 | 212篇 |
2021年 | 269篇 |
2020年 | 331篇 |
2019年 | 318篇 |
2018年 | 314篇 |
2017年 | 336篇 |
2016年 | 458篇 |
2015年 | 572篇 |
2014年 | 765篇 |
2013年 | 998篇 |
2012年 | 1137篇 |
2011年 | 1091篇 |
2010年 | 905篇 |
2009年 | 951篇 |
2008年 | 710篇 |
2007年 | 1157篇 |
2006年 | 1261篇 |
2005年 | 954篇 |
2004年 | 775篇 |
2003年 | 781篇 |
2002年 | 650篇 |
2001年 | 541篇 |
2000年 | 507篇 |
1999年 | 437篇 |
1998年 | 327篇 |
1997年 | 269篇 |
1996年 | 220篇 |
1995年 | 186篇 |
1994年 | 143篇 |
1993年 | 130篇 |
1992年 | 58篇 |
1991年 | 50篇 |
1990年 | 29篇 |
1989年 | 8篇 |
1988年 | 12篇 |
1987年 | 3篇 |
1986年 | 14篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1970年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
31.
Photocatalytic degradation of phenol 总被引:3,自引:0,他引:3
In this study photocatalytic degradation of phenol in thepresence of UV irradiated TiO2 catalyst andH2O2was investigated. Effects of TiO2 andH2O2concentrations and pH on photocatalytic degradation were examined. The rate constants for photocatalytic degradation wereevaluated as a function of TiO2 and H2O2 concentrations and pH of the solution. It was found thatphotodegradation is an effective method for the removal of phenoland disappearance of phenol obeyed first order kinetics. The amount of CO2h produced during photocatalytic degradation wascorresponding to the complete mineralization. Photodegradationcan be an alternative method for the treatment of phenol containing wastewaters. 相似文献
32.
Llansó RJ Dauer DM Vølstad JH Scott LC 《Environmental monitoring and assessment》2003,81(1-3):163-174
The Chesapeake Bay benthic index of biotic integrity (B-IBI) was developed to assess benthic community health and environmental quality in Chesapeake Bay. The B-IBI provides Chesapeake Bay monitoring programs with a uniform tool with which to characterize bay-wide benthic community condition and assess the health of the Bay. A probability-based design permits unbiased annual estimates of areal degradation within the Chesapeake Bay and its tributaries with quantifiable precision. However, of greatest interest to managers is the identification of problem areas most in need of restoration. Here we apply the B-IBI to benthic data collected in the Bay since 1994 to assess benthic community degradation by Chesapeake Bay Program segment and water depth. We used a new B-IBI classification system that improves the reliability of the estimates of degradation. Estimates were produced for 67 Chesapeake Bay Program segments. Greatest degradation was found in areas that are known to experience hypoxia or show toxic contamination, such as the mesohaline portion of the Potomac River, the Patapsco River, and the Maryland mainstem. Logistic regression models revealed increased probability of degraded benthos with depth for the lower Potomac River, Patapsco River, Nanticoke River, lower York River, and the Maryland mainstem. Our assessment of degradation by segment and water depth provided greater resolution of relative condition than previously available, and helped define the extent of degradation in Chesapeake Bay. 相似文献
33.
34.
35.
分光光度法测定染色废水的色度 总被引:3,自引:0,他引:3
为消除测定染色废水色度的主观误差,采用分光光度法测定染色废水的色度,与稀释倍数法相比,具有精确,重现性好,适用范围广等特点,PH值对色度的测定有明显影响,控制PH值为7.60,测定色度具有可比性。 相似文献
36.
37.
Danuta Zimakowska-Gnoińska Jaume Bech Francisco J. Tobias 《Environmental monitoring and assessment》2000,61(2):301-313
A main goal of investigations is to determine could a soilrespiration be an indicator of the soil pollution. In this case a measured levelof the soil oxygen consumption depends of its pollution. It alsomeans that the pollution reduces biological processes in edaphon.Investigated soil samples were taken from polluted andnon-polluted places in the Baix Llobregat near Barcelona (Catalonia, NE Spain). Soil samples were taken from the top ofsoil (0–5 cm) without a litter. Soil analysis were done, determining percentage shares of coarsefragments, coarse sand, fine sand, coarse silt, fine silt, clay,CaCO3, organic matter as well as water pH and conductivityCE (1:5 [mS cm-1]). Also were determined (in mg kg-1)quantities of heavy metals, as Fe, Al, Mn, Zn, Cr, Ni, V, Cu, Cd, Pb.The soil respiration was investigated in temperatures15 and 30 °C and with controlled humidity.The respiration in 30 °C is number of times greater thenin 15 °C both for polluted and non-polluted soils.Particularly high coefficients of correlation between the soilrespiration and soil pollution in polluted soils were obtainedfor Pb: r = 0.75 in 15 °C and r = 0.98 in30 °C; for Ba: 0.90 and 0.57; for V: 0.99 and 0.81. In non-polluted soils highest correlation coefficients are for Pb: r = 0.70 in 15 °C; Fe: 0.60 and 0.72; Al: 0.68 and0.64; Mn: 0.51 and 0.66; Ba: 0.63 and 0.61; Cr: 0.94 and0.70; Ni: 0.64 and 0.65; Cu: 0.69 and 0.48; as well as V: 0.62in 15 °C; and Cd: 0.69 in 15 °C.This way the soil respiration could be a good indicator of the soil pollution. 相似文献
38.
密切值法在污染源治理方案优选中的应用 总被引:5,自引:0,他引:5
本文采用密切值法进行污染源多个治理方案的优化决策研究,并通过实例分析获得了与实际状况相符合的优化结果。 相似文献
39.
IntroductionEightypercentoforganicsubstancesinthesourcewaterisfromcrudehumicacidthatisacrudeorganiccompoundcreatedbyrottinganddecomposinginnaturalcycle ,thehighercontentofhumicacidis ,theworsequalityofthewateris,notonlycanitcausechrominance,offensiveodor,… 相似文献
40.
对多环芳烃(PAHS)4种理化参数(K;W、Sw。X Vv。)与 LCO的相关关系进行了研究,建立了 4种一元线性回归方程。结果表明,4种参数的相关系数分别为:0.刀66、08083、09488、0.9570,经r检验,后两种属高度显著相关.用所建立的一元线性回归方程对7种PAHS的LC。进行估算,估算值与实测值相比,平均相对误差分别为58.84%、32.23%、1761%、198%,用l和V*.H对LClj进行估算的估算精度也较高。经比较,提出用(。估算P*比对麦穗鱼*CO的新方法。 相似文献