全文获取类型
收费全文 | 8258篇 |
免费 | 29篇 |
国内免费 | 59篇 |
专业分类
安全科学 | 187篇 |
废物处理 | 430篇 |
环保管理 | 717篇 |
综合类 | 1209篇 |
基础理论 | 2419篇 |
环境理论 | 1篇 |
污染及防治 | 1895篇 |
评价与监测 | 580篇 |
社会与环境 | 881篇 |
灾害及防治 | 27篇 |
出版年
2023年 | 42篇 |
2022年 | 78篇 |
2021年 | 65篇 |
2020年 | 30篇 |
2019年 | 44篇 |
2018年 | 185篇 |
2017年 | 204篇 |
2016年 | 288篇 |
2015年 | 120篇 |
2014年 | 158篇 |
2013年 | 434篇 |
2012年 | 578篇 |
2011年 | 446篇 |
2010年 | 237篇 |
2009年 | 245篇 |
2008年 | 299篇 |
2007年 | 312篇 |
2006年 | 303篇 |
2005年 | 593篇 |
2004年 | 703篇 |
2003年 | 613篇 |
2002年 | 216篇 |
2001年 | 290篇 |
2000年 | 179篇 |
1999年 | 130篇 |
1998年 | 45篇 |
1997年 | 67篇 |
1996年 | 56篇 |
1995年 | 70篇 |
1994年 | 68篇 |
1993年 | 61篇 |
1992年 | 61篇 |
1991年 | 68篇 |
1990年 | 70篇 |
1989年 | 56篇 |
1988年 | 56篇 |
1987年 | 54篇 |
1986年 | 55篇 |
1985年 | 41篇 |
1984年 | 47篇 |
1983年 | 47篇 |
1982年 | 48篇 |
1980年 | 30篇 |
1979年 | 32篇 |
1978年 | 29篇 |
1977年 | 28篇 |
1976年 | 28篇 |
1974年 | 33篇 |
1973年 | 31篇 |
1972年 | 29篇 |
排序方式: 共有8346条查询结果,搜索用时 281 毫秒
111.
112.
113.
Duodenal stenosis associated with oesophageal atresia was diagnosed by ultrasound at 12 weeks' gestation. The diagnosis was made by recognition of a double bubble sign which was more pronounced when a vaginal transducer was used. Post-abortion autopsy confirmed the diagnosis. Oesophageal and duodenal obstruction in this case had no effect on the amount of amniotic fluid or the alpha-fetoprotein concentration since swallowing and subsequent utilization of amniotic fluid do not occur before 12 weeks of gestation. 相似文献
114.
C. Sheinbaum I. Jauregui L. Rodríguez V. 《Mitigation and Adaptation Strategies for Global Change》1998,2(4):359-372
An analysis of the impacts on Mexican energy demand and associated carbon dioxide (CO2) emissions in the year 2005 due to efficient lighting in the commercial and residential sectors and cogeneration in the industrial sector is presented. Estimation of CO2 abatement costs and an incremental cost curve for CO2 mitigation options are considered. These technologies are cost effective opportunities, and together are projected to reduce CO2 emissions in 2005 by nearly 13 percent. Implementation of efficient lighting is already part of the demand side management (DSM) programs of the Mexican state-owned utility. However, there are important barriers that may hinder the implementation of large scale cogeneration plants. 相似文献
115.
I. Shagina H. L. Dadali V. P. Sitnikov V. V. Pugachev N. A. Malygina O. V. Evgrafov 《黑龙江环境通报》1995,15(1):27-34
Ninety-two families with spinal muscular atrophy (SMA) applied for genetic counselling and further prenatal diagnosis. To minimize expenses, only one tightly linked informative marker was determined in the course of preliminary examination, and non-radioactive allele detection was preferably used. Four prenatal diagnoses of SMA type I, four of SMA type II, and one of SMA type III were made. This trial programme shows the considerable requirements, importance, and potential effectiveness of prenatal prediction of SMA in Russia. 相似文献
116.
P. Robbins-Furman J. T. Hecht M. Rocklin N. Maklad G. Greenhaw I. Wilkins MD 《黑龙江环境通报》1995,15(2):179-182
The diagnosis of Freeman–Sheldon syndrome was made by ultrasonographic evaluation of a 20-week fetus with a positive family history. The ultrasonographic features were abnormalities of the extremities and mouth. 相似文献
117.
In Acromyrmex octospinosus leaf-cutting ants the metapleural glands produce an array of antibiotic compounds that serve as a general defence against unwanted microbes on the cuticle. Leaf-cutting ants also grow mutualistic Pseudonocardiaceae bacteria on their cuticle that produce antibiotics controlling a microfungal parasite of their fungus gardens. Interaction between this bacterium and gland secretion therefore seems unavoidable. We document the typical development of bacterial growth on the cuticle of young major workers, show that growth starts a few days after eclosion, and that the maximal cover is reached after 2–3 weeks and gradually declines when workers mature. Experimental closure of the metapleural glands had no effect on the initial exponential growth phase of the bacterium, but significantly reduced the cover during the decline phase. The age-dependent abundance of the bacterium and its partial dependence on metapleural gland secretion support the hypothesis that the abundance of this mutualist is actively regulated. 相似文献
118.
119.
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
120.
In several branches of science and technology a gaseous phase is dispersed into a liquid in the form of bubbles, a gaseous
component then dissolves into the liquid and subsequently undergoes chemical reaction. The overall process performance can
be improved substantially when the area of gas–liquid contact is increased. By subjecting the liquid phase to low frequency
vibrations, the bubbles are shown to suffer significant breakage, induced by resonance. When the vibration is properly tuned,
the interfacial area is found to increase by a factor of 1.8–2.4, depending on the properties of the liquid. Resonance-induced
bubble breakage phenomena have a great potential for improving the rates of chemical processes involving fast reactions, with
minimal energy input.
Received: 7 July 2000 / Accepted in revised form: 28 August 2000 相似文献