全文获取类型
收费全文 | 19076篇 |
免费 | 172篇 |
国内免费 | 159篇 |
专业分类
安全科学 | 368篇 |
废物处理 | 750篇 |
环保管理 | 1965篇 |
综合类 | 5057篇 |
基础理论 | 4257篇 |
环境理论 | 10篇 |
污染及防治 | 4653篇 |
评价与监测 | 1167篇 |
社会与环境 | 1122篇 |
灾害及防治 | 58篇 |
出版年
2022年 | 145篇 |
2021年 | 150篇 |
2019年 | 129篇 |
2018年 | 250篇 |
2017年 | 238篇 |
2016年 | 378篇 |
2015年 | 290篇 |
2014年 | 439篇 |
2013年 | 1225篇 |
2012年 | 503篇 |
2011年 | 687篇 |
2010年 | 571篇 |
2009年 | 650篇 |
2008年 | 736篇 |
2007年 | 798篇 |
2006年 | 695篇 |
2005年 | 582篇 |
2004年 | 600篇 |
2003年 | 602篇 |
2002年 | 556篇 |
2001年 | 677篇 |
2000年 | 463篇 |
1999年 | 347篇 |
1998年 | 228篇 |
1997年 | 249篇 |
1996年 | 247篇 |
1995年 | 270篇 |
1994年 | 266篇 |
1993年 | 242篇 |
1992年 | 211篇 |
1991年 | 238篇 |
1990年 | 225篇 |
1989年 | 190篇 |
1988年 | 190篇 |
1987年 | 168篇 |
1986年 | 167篇 |
1985年 | 174篇 |
1984年 | 187篇 |
1983年 | 176篇 |
1982年 | 194篇 |
1981年 | 156篇 |
1980年 | 151篇 |
1979年 | 155篇 |
1978年 | 156篇 |
1977年 | 136篇 |
1974年 | 128篇 |
1967年 | 145篇 |
1964年 | 124篇 |
1963年 | 126篇 |
1957年 | 124篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Kenneth L. Garver Miriam G. Blitzer Gladys Ibezim Sandra G. Marchese Dolores L. Pegram Anita M. Hagins Wnjing Zhang 《黑龙江环境通报》1984,4(2):109-112
Using a modified procedure by Solomons and Styner (1969), an evaluation of inorganic pyrophosphate (PPi) was performed on the amniotic fluid of two fetuses at risk for osteogenesis imperfecta (OI) at 14½ weeks gestation. The parents of both cases had a previous child with OI, Type II. The normal control group at 14–16 weeks gestation had PPi values ranging from 22.0–59.2 ug/100 ml, with a mean of 38.6±9.51 ug/100 ml. In each at-risk fetus, the amniotic fluid PPi value was within normal range. The first baby was born phenotypically normal at term. Intrauterine radiographic and fetal sonograms were done on the second fetus at approximately 19 weeks gestation. Both showed evidence of OI, Type II. The pregnancy was terminated at 21 weeks. Radiologic studies of the aborted fetus were consistent with OI, Type II. Our results indicate that the evaluation of PPi levels in amniotic fluid is not the method of choice for prenatal diagnosis of IO. 相似文献
102.
With the advent of more stringent controls on wastewater treatment, sewage sludge production in Europe and many parts of the world is increasing. With this increase comes the problem of sludge disposal, and recycling to land arguably offers an economically and environmentally sustainable option. However, a major limitation of sewage sludge reuse is the potential release of heavy metals from the sludge and heavy metal accumulation to toxic levels in topsoils. The properties of the sludge play a crucial role in determining the initial release and subsequent availability of heavy metals in amended soils. Bioavailable forms of heavy metals in recently amended soils are most likely to be those that are bioavailable in the sewage sludge. In this paper, published research on the importance of sewage sludge characteristics on metal release and bioavailability will be reviewed and contrasted with original research. A selection of sludges from around Australia has been collected for this purpose. Through the use of incubation studies, isotope dilution techniques, ion-selective electrode measurements and 13C-NMR spectroscopy, the importance of a range of sludge properties on heavy metal behaviour in sludges and sludge-amended soils is addressed. 相似文献
103.
Microorganisms are able to synthesize three different polyamides by enzymatic processes independently from ribosomal protein biosynthesis: poly(gamma-D-glutamic acid), poly(epsilon-L-lysine) and multi-L-arginyl-poly(L-aspartic acid) which is also referred to as cyanophycin. These polyamides, which occur mainly in Bacillus spp. (and only a few other eubacteria and the nematocysts of Cnidaria, in Streptomyces albulus or in cyanobacteria, respectively), have recently attracted considerable interest of the chemical industry and may be suitable for various applications. This review summarizes our current knowledge on the occurrence, biosynthesis, physiological functions, and biodegradation as well as on the properties and putative applications of these polyamides. Emphasis is placed on the enzymology of the polymerization and on the genes encoding the polymerizing enzymes, which have only recently become available for cyanophycin synthetases. Prospects for novel production processes. in particular for cyanophycin, are also presented. 相似文献
104.
105.
106.
Flavonoid wing pigments increase attractiveness of female common blue (Polyommatus icarus) butterflies to mate-searching males 总被引:1,自引:0,他引:1
Common blue butterflies (Polyommatus icarus) sequester flavonoids from their larval host plants and allocate these UV-absorbing pigments to the wings. In field experiments
using dummies constructed from female butterflies, mate-searching males inspected flavonoid-rich dummies more intensively
than those with little or no flavonoids. Flavonoid content as signalled by UV-wing pattern may indicate ontogenetically determined
female quality or enhance detectability to males.
Received: 21 March 2000 / Accepted in revised form: 17 May 2000 相似文献
107.
108.
109.
Intergeneric transmission of a marine plant DNA virus 总被引:1,自引:0,他引:1
D. G. Müller 《Die Naturwissenschaften》1992,79(1):37-39
110.