全文获取类型
收费全文 | 48091篇 |
免费 | 1228篇 |
国内免费 | 6366篇 |
专业分类
安全科学 | 2261篇 |
废物处理 | 2544篇 |
环保管理 | 5167篇 |
综合类 | 14672篇 |
基础理论 | 10871篇 |
环境理论 | 20篇 |
污染及防治 | 13869篇 |
评价与监测 | 2964篇 |
社会与环境 | 2455篇 |
灾害及防治 | 862篇 |
出版年
2023年 | 418篇 |
2022年 | 1130篇 |
2021年 | 1063篇 |
2020年 | 819篇 |
2019年 | 797篇 |
2018年 | 1174篇 |
2017年 | 1245篇 |
2016年 | 1634篇 |
2015年 | 1658篇 |
2014年 | 2213篇 |
2013年 | 4181篇 |
2012年 | 2480篇 |
2011年 | 2916篇 |
2010年 | 2401篇 |
2009年 | 2412篇 |
2008年 | 2754篇 |
2007年 | 2596篇 |
2006年 | 2343篇 |
2005年 | 1812篇 |
2004年 | 1534篇 |
2003年 | 1677篇 |
2002年 | 1502篇 |
2001年 | 1742篇 |
2000年 | 1398篇 |
1999年 | 943篇 |
1998年 | 679篇 |
1997年 | 713篇 |
1996年 | 659篇 |
1995年 | 670篇 |
1994年 | 647篇 |
1993年 | 517篇 |
1992年 | 520篇 |
1991年 | 440篇 |
1990年 | 469篇 |
1989年 | 387篇 |
1988年 | 341篇 |
1987年 | 310篇 |
1986年 | 252篇 |
1985年 | 266篇 |
1984年 | 286篇 |
1983年 | 274篇 |
1982年 | 271篇 |
1981年 | 241篇 |
1980年 | 183篇 |
1979年 | 201篇 |
1978年 | 187篇 |
1975年 | 150篇 |
1974年 | 123篇 |
1972年 | 137篇 |
1971年 | 135篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
411.
412.
综述了重金属和部分有机化合物对藻类的生态毒理效应,并探讨了藻类对污染物的富集和降解机制.大量研究证实,重金属对藻类在各个水平上均产生影响,但不同重金属对不同的藻种有不同的毒性效应.而有机物对藻类的影响则可归纳为4个方面. 相似文献
413.
洗煤水治理矸石山自燃对地下水的影响研究 总被引:2,自引:0,他引:2
1 引言 煤矸石自燃是矿区主要环境问题之一。经过多年的实践研究,目前矸石山灭火采用的方法主要有:水力灭火法、包裹覆盖法、胶泥注射—覆盖灭火法等。其中水力灭火法,是将不能饮用的水作为灭火用水,,是目前矿区自燃矸石山灭火的首选方法。晋城矿务局凤凰山矿从1997年起采用洗煤 相似文献
414.
本文介绍了在实验室中运用压差式仪器法测定BOD值的优越性,并着重与相应的化学稀释法所测BOD值进行对照.通过计算机找出二者的相关关系,以便得到准确的BOD值进而推广利用BOD测定的新技术. 相似文献
415.
Prenatal diagnosis in a pregnancy at risk for a juvenile B1 variant of GM2-gangliosidosis was carried out. The biochemical study of the cultured amniocytes and the affected fetal brain is reported. The results obtained show that the sulphated artificial substrate can be used in the diagnosis of B1 variant, but not the neutral one. The accumulation of GM2-ganglioside in the fetal brain of the B1 juvenile form and an infantile form of GM2-gangliosidosis (0 variant) was compared. 相似文献
416.
Prenatal diagnosis on chorionic villous tissue was performed for a woman with the karyotype 46,XX,t(2;18)(q32;q12)—a subtle ‘difficult’ translocation. The case illustrates the necessity of good quality cytogenetics for accurate prenatal diagnosis. For chorionic villi this can be obtained only with long-term culture. 相似文献
417.
P. A. Hurley Mr R. H. T. Ward B. Teisner R. K. Iles M. Lucas J. G. Grudzinskas 《黑龙江环境通报》1993,13(10):903-908
Serum PAPP-A measurements taken from 254 women in the first trimester are reported. Eleven chromosomal abnormalities were detected. The mean serum PAPP-A levels in cases of Down syndrome were 0.44 MOM at 9 weeks gestation, 0.15 MOM at 10 weeks, and 0.29 MOM at 11 weeks. The PAPP-A level at 10 weeks was below those of pregnancies which aborted spontaneously. At 11 weeks, the pregnancies with Down syndrome recorded the lowest PAPP-A levels at that gestation. On this small sample, offering chorionic villus sampling to women with singleton pregnancies and a PAPP-A level below 0.3 MOM (approximately 6.5 per cent of this at-risk group) would have detected all the Down syndrome fetuses at 10 weeks and 50 per cent at 11 weeks without selecting those cases destined to abort. This suggests that serum PAPP-A should continue to be investigated as a potential first-trimester screening test for Down syndrome. 相似文献
418.
A laboratory scale study was conducted to assess the feasibility of the new coupling of rotating biological contactor (RBC) plus porous biomass support system (PBSS) using polyurethane foam as porous support media to biodegrade petroleum refinery wastewater. Polyurethane foam was attached on disks of two four-stage laboratory scale cascade connected RBC units.The two RBC units were operated simultaneously at different but constant, flowrates giving hydraulic loading rates of 0.01, 0.02, 0.03, 0.04 m3/m2/d in two runs keeping the same rotational speed 10 r/min throughout. Organic loading was a less controllable factor in this study.For all of the hydraulic loadings, it was found that the removal efficiency of total chemical oxygen demand (TCOD) and oil were above 80 percent. Ammonia nitrogen and phenol removal were above 90 and 80 percent respectively. The maximum biomass concentration within polyurethane foam was about 30 g/m2 in the first stage for 0.03 m3/m2/d hydraulic loading.The results show that t 相似文献
419.
Wu Jin Wang Anpu Huang Yanchu Ma ciguang Y. Ii S. Daishim K. Furuy T. Kikuchi H. Matsushit K. Tanabe 《环境科学学报(英文版)》1990,2(1):27-39
A study has been made on elements organic constituents, TSP, SO2,NO2 of atmospheric pollutants in Beijing. 17 elements, and some PAHs, e. g. B(a)P, B(b, j, k)P, and B(g, h, i)P, in airborne particles by X-ray fluorescence spectroscopy and HPLC, GC/MS, have been determined respectively. It has been shown that the elements Pb, Zn, S and Cu were more enriched in fine particles and different valence states of sulfur at various sites. It was found that the concentrations of S6+ and S2-were more than 85% and less than 15% of the total sulfur respectively. Concentrations of major PAHs and sulfur-containing compounds increased in winter and in urban area. High values for Pb and Zn in city, Fe and Mn at industrial area and Cu, Al rural sites were obtained respectively. This implies the functions of different elemental sources of various sites. Thus, elements can be from distingushed anthropogenic and natural sources.The main contribution of SO2 was found of to have same seasonal variation as the anthropogenic el 相似文献
420.