全文获取类型
收费全文 | 562篇 |
免费 | 2篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 4篇 |
废物处理 | 14篇 |
环保管理 | 26篇 |
综合类 | 270篇 |
基础理论 | 107篇 |
环境理论 | 1篇 |
污染及防治 | 102篇 |
评价与监测 | 20篇 |
社会与环境 | 23篇 |
灾害及防治 | 2篇 |
出版年
2018年 | 7篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2013年 | 21篇 |
2012年 | 12篇 |
2011年 | 16篇 |
2010年 | 12篇 |
2009年 | 18篇 |
2008年 | 18篇 |
2007年 | 21篇 |
2006年 | 22篇 |
2005年 | 27篇 |
2004年 | 17篇 |
2003年 | 17篇 |
2002年 | 34篇 |
2001年 | 14篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1996年 | 8篇 |
1995年 | 12篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1968年 | 3篇 |
1967年 | 4篇 |
1966年 | 8篇 |
1965年 | 11篇 |
1964年 | 11篇 |
1963年 | 9篇 |
1962年 | 11篇 |
1961年 | 11篇 |
1960年 | 18篇 |
1959年 | 10篇 |
1958年 | 10篇 |
1957年 | 10篇 |
1956年 | 10篇 |
1955年 | 6篇 |
1954年 | 5篇 |
1951年 | 5篇 |
排序方式: 共有569条查询结果,搜索用时 0 毫秒
541.
We investigated unhatched eggs (n = 57) of Goshawks (Accipiter gentilis) from the period 1988--2002 and compared them with eggs (n = 134) from 1971--1978. Mean concentrations of PCBs, sigmaDDT and HCB in the earlier period were (mg kg(-1) lipid weight) 50.1, 126.6, and 117.7, while the values from the later period were statistically significantly lower: 27.7, 4.1, 0.1, respectively. Nevertheless, the concentration of PCB is relatively constant during the last 8-10 years. The variability of residues was lower within clutches than among clutches. No age-dependent accumulation in eggs could be demonstrated. A statistically significant lower shell index was measurable for the period 1971--1978, while this index during 2001--2002 was relatively high as it was during the late 18th century. We are suggesting a threshold value for effect concentrations on shell index. Residues of the DDT-group had an influence on the number of fledged young per nest site. 相似文献
542.
The Science of Nature - 相似文献
543.
544.
545.
546.
547.
548.
A case of a prenatally diagnosed fetal ovarian cyst is presented. The pregnancy was complicated only by polyhydramnios, and some degree of fetal bowel obstruction could be recognized on sonogram. The newborn was delivered vaginally in the 39th week of pregnancy, and the cyst was removed by laparotomy on the day of the delivery. The etiology of this rare fetal condition is unknown. 相似文献
549.
Koch W Dunkhorst W Lödding H Thomassen Y Skaugset NP Nikano A Vincent J 《Journal of environmental monitoring : JEM》2002,4(5):657-662
The Respicon has been introduced as a sampler for health related measurements of airborne contaminants at workplaces. The instrument is aimed at simultaneous collection of three health related aerosol fractions: (a) the coarser inhalable fraction, defining the aerosol fraction that may enter the nose and mouth during breathing; (b) the intermediate thoracic fraction, defining the fraction that may penetrate beyond the larynx and so reach the lung; and (c) the finer respirable fraction, defining the fraction that may penetrate to gas exchange region of the lung. The instrument has a number of features attractive to occupational hygienists: in addition to providing the three aerosol fractions simultaneously, it is light and compact enough to be used as a personal sampler. yet can be a tripod mounted for area sampling, it can provide samples not only for gravimetric analysis but also microscopic and chemical analyses; and it is also available in a photometric direct-reading version. The instrument has previously been evaluated as an area sampler and, in this mode of operation, has shown reasonable accuracy in collecting respirable, thoracic and inhalable particles, the latter up to particle diameters of ca. 80 microm. Except for some scattered unpublished data there exist no systematic investigations in the Respicon's performance when used as a personal sampler in the industrial environment. In this paper, we will report on a study of side by side comparison of the Respicon with the IOM inhalable sampler, regarded as a reference instrument for the inhalable fraction. The main study was performed at six different workplaces in a nickel refinery. Statistical analysis of the gravimetrically-determined concentration data reveals consistently lower aerosol exposure values for the Respicon as compared to the IOM sampler. The data for the nickel workplaces are compared with findings from other studies. The results are interpreted in the light of the overall results and the possibility of introducing a correction factor is discussed. 相似文献
550.
Guillermo Palau-Salvador Manuel García-Villalba Wolfgang Rodi 《Environmental Fluid Mechanics》2011,11(6):611-625
This paper presents a large eddy simulation of mass transfer in the flow around a surface-mounted finite-height circular cylinder.
The study was carried out for a cylinder with height-to-diameter ratio of 2.5 and a Reynolds number based on the cylinder
diameter of 44000. The approach flow boundary layer had a thickness of about 10% of the cylinder height. A tracer was released
at various levels upstream of the cylinder. The effect of the release position in the subsequent spreading and dilution of
the plumes is analyzed. It is found that a tracer released at the top or at mid-height is entrained into the recirculation
zone behind the cylinder, and therefore presents similar plume evolution in the far wake in both cases. If the tracer is released
at around three-quarters of the height of the cylinder, it is not significantly entrained by the main recirculation region,
leading to smaller rates of spreading of the plume. Finally, if the tracer is released near the floor, the plume is entrained
by the horseshoe vortex that wraps around the cylinder, leading to a large lateral spreading of the plume, remaining always
near the floor. 相似文献