全文获取类型
收费全文 | 23645篇 |
免费 | 407篇 |
国内免费 | 1374篇 |
专业分类
安全科学 | 776篇 |
废物处理 | 1194篇 |
环保管理 | 2664篇 |
综合类 | 4626篇 |
基础理论 | 5838篇 |
环境理论 | 6篇 |
污染及防治 | 6626篇 |
评价与监测 | 1808篇 |
社会与环境 | 1621篇 |
灾害及防治 | 267篇 |
出版年
2023年 | 165篇 |
2022年 | 398篇 |
2021年 | 411篇 |
2020年 | 289篇 |
2019年 | 271篇 |
2018年 | 476篇 |
2017年 | 482篇 |
2016年 | 695篇 |
2015年 | 556篇 |
2014年 | 863篇 |
2013年 | 2073篇 |
2012年 | 952篇 |
2011年 | 1157篇 |
2010年 | 1008篇 |
2009年 | 995篇 |
2008年 | 1126篇 |
2007年 | 1129篇 |
2006年 | 1055篇 |
2005年 | 862篇 |
2004年 | 811篇 |
2003年 | 813篇 |
2002年 | 749篇 |
2001年 | 993篇 |
2000年 | 729篇 |
1999年 | 478篇 |
1998年 | 360篇 |
1997年 | 322篇 |
1996年 | 363篇 |
1995年 | 327篇 |
1994年 | 292篇 |
1993年 | 265篇 |
1992年 | 283篇 |
1991年 | 219篇 |
1990年 | 222篇 |
1989年 | 225篇 |
1988年 | 205篇 |
1987年 | 161篇 |
1986年 | 127篇 |
1985年 | 139篇 |
1984年 | 172篇 |
1983年 | 153篇 |
1982年 | 194篇 |
1981年 | 135篇 |
1980年 | 119篇 |
1979年 | 152篇 |
1978年 | 118篇 |
1977年 | 107篇 |
1976年 | 100篇 |
1975年 | 83篇 |
1974年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 956 毫秒
381.
Mitigation and Adaptation Strategies for Global Change - Guidelines of the Intergovernmental Panel on Climate Change (IPCC) were used to assess a greenhouse gas inventory for land use change and... 相似文献
382.
383.
用植物清除土壤中的重金属 总被引:11,自引:0,他引:11
介绍了生物修复技术去除土壤中的重金属及对植物的要求.植物能去除土壤中的有毒金属,将金属富集在生物体内,或将金属变成挥发性气体. 相似文献
384.
The groundwater regime in Upper Palar basin, Tamilnadu has been highly contaminated in several locations due to discharge of effluents from a large number of tanneries. At some places total dissolved solids (TDS) concentration in groundwater was found as high as 8000 mg/l. Transmissivity and storativity of the regional aquifer were estimated at a few locations. The porosity and dispersivity values were not determined in the field. These parameters were assumed based on data available for similar geological formations elsewhere. The aquifer conceptualization thus arrived at formed the basis of a numerical groundwater flow model which was constructed using the finite difference method. The flow model was calibrated for steady state and then for transient condition for the period of 1984-92. The computed heads and calibrated parameters of the flow model were used to compute groundwater velocities. The migration of contaminants for a 20 year period was computed using the hydraulic heads and effective porosity value in a pathline model using FLOWPATH software. Mass transport model was constructed using Method of Characteristics (MOC) computer code in a separate model. The seepage rate of effluent is assumed at a rate of 30% of that discharged on the surface. The mass concentration of solute in the effluent reaching the water table was assumed as 40%, the same as in the surface effluent. The mass transport model was calibrated for a 20 year period. Prediction of contaminant migration from different clusters in the basin was analyzed. The prediction results indicated elevated TDS concentration of more than 4000 mg/l from most clusters. Also the area of the contaminated zone is likely to double in 20 years from contaminated zone of 1992. 相似文献
385.
脉冲等离子法烟气脱硫的放大实验 总被引:2,自引:0,他引:2
锅炉烟气进行脉冲等离子法脱硫的扩大实验,得到与模拟烟气实验相近的结果。研究表明,脉冲等离子法对锅炉烟气中的SO2去除率可达95%以上,烟气在反应器内的停留时间(ts)、脉冲电源的放电功率(P)和添加NH3等条件,对脱硫效率9η)有较大影响。ts、P越大、η越高。处理烟气量(Q)、能耗(P)与η存在函数关系:η=118.0(P/Q)^0.1111。烟气中加入适量NH3,对脱硫效率有显著提高,以NH3 相似文献
386.
387.
388.
389.
Maternal serum alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (βhCG) measurements taken prior to chorionic villus sampling (CVS) in 21 patients who subsequently miscarried were compared with measurements in a control group of 113 patients with uneventful pregnancies. Patients with AFP levels of 10 iu/ml or more prior to the CVS had a 4·3 times greater risk of miscarriage (95 per cent confidence interval 1·3–13·6). AFP levels obtained 1 week after the CVS in the 13 patients with late miscarriages were higher than in the control group (P = 0·06). Patients miscarrying had a greater rise in AFP (P = 0·06) and a greater fall in βhCG levels (P = 0·04) following the CVS procedure, compared with the control subjects. Each 10-unit change in the difference between AFP or βhCG levels prior to and 1 week following the CVS was associated with a significantly increased risk for late miscarriage. Elevated maternal serum AFP levels early in pregnancy and changes in AFP and βhCG levels following CVS may predict an increased risk for subsequent miscarriage. 相似文献
390.