首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   250篇
  免费   0篇
  国内免费   2篇
安全科学   6篇
废物处理   22篇
环保管理   27篇
综合类   52篇
基础理论   54篇
污染及防治   67篇
评价与监测   20篇
社会与环境   4篇
  2023年   1篇
  2022年   9篇
  2021年   8篇
  2020年   5篇
  2019年   8篇
  2018年   4篇
  2017年   10篇
  2016年   15篇
  2015年   13篇
  2014年   17篇
  2013年   24篇
  2012年   9篇
  2011年   11篇
  2010年   9篇
  2009年   15篇
  2008年   18篇
  2007年   10篇
  2006年   12篇
  2005年   10篇
  2004年   8篇
  2003年   8篇
  2002年   6篇
  1999年   1篇
  1998年   2篇
  1994年   1篇
  1992年   3篇
  1991年   2篇
  1989年   1篇
  1988年   2篇
  1986年   4篇
  1984年   1篇
  1961年   1篇
  1960年   1篇
  1940年   1篇
  1938年   2篇
排序方式: 共有252条查询结果,搜索用时 15 毫秒
71.
The aim of the study is to investigate how environmental factors, associated with exposure to industrial noise, affect the development of chronic noise-induced hearing loss.The studywas conducted on 186 male subjectsworking in two bottling plants, situated respectively in a small farming community, and in a medium-sized city with significant levels of noise pollution. Levels of occupational exposure were the same for the two groups.The subjects were selected by means of a preliminary medical examination, and exposed to tonal hearing tests and acoustic impedance tests. Statistical analysis was performed on hearing threshold values obtained at the frequencies of 500, 1000, 2000 and 4000 Hz.The comparison between the thresholds obtained in the two groups showed a statistically significant difference, especially at the frequency of 4000 Hz and for occupational exposure exceeding 17 yr. The results led us to conclude that environmental factors, and urban noise in particular, influence the onset and development of occupational acoustic trauma, and that those working in the country are significantly less affected than those in the city. Since occupational exposure was the same for both groups, their different responses must therefore be interpreted as due to differences in nonoccupational exposure, in turn dependent on different opportunities for rest from noise and different levels of exposure to noise pollution.  相似文献   
72.
The purpose of this study was to evaluate “in field” the accumulation of virus in shellfish and compare it with the concentration of bacterial indicators. Individuals of Mytilus galloprovincialis were placed in two sampling station located in a contaminated coastal bay and in one control station located one kilometer offshore. The presence of Rotavirus and E. coli was assessed weekly both in seawater and in shellfish samples. The Rotavirus genome was detected in water, preliminarily concentrated by tangential flow ultrafiltration method, and in hepatopancreas of mussels by Real-Time PCR. E. coli was enumerated in water matrices by a filtering method and in mussels by the MPN method. Rotaviruses were not recorded in seawater, while in mussels they were detected since third week after placement. E. coli in mussels were always below the limits set in the Regulation (EC) 854/2004. This study suggests the need for a viral indicator to insure the safety for consumption of shellfish.  相似文献   
73.
74.
Bivalve mollusks as filter-feeders concentrate in their digestive tissue microorganisms likely present in the harvesting water, thus becoming risky food especially if consumed raw or poorly cooked. To eliminate bacteria and viruses eventually accumulated, they must undergo a depuration process which efficacy on viruses is on debate. To better clarify the worth of the depuration process on virus elimination from mussels, in this study we investigated rotavirus kinetics of accumulation and depuration in Mytilus galloprovincialis experimentally contaminated. Depuration process was monitored for 9 days and virus residual presence and infectivity were evaluated by real time quantitative polymerase chain reaction, cell culture and electron microscopy at days 1, 2, 3, 5, 7, 9 of depuration. Variables like presence of ozone and of microalgae feeding were also analyzed as possible depuration enhancers. Results showed a two-phase virus removal kinetic with a high decrease in the first 24 h of depuration and 5 days necessary to completely remove rotavirus.  相似文献   
75.
76.
77.
In this paper we report the fetal loss rate in relation to both maternal and gestational age in 1764 pregnant women who underwent transabdominal chorionic villus sampling (TA-CVS) between January 1986 and August 1990. The fetal loss rate, considered as a proportion of continuing pregnancies, decreased with advancing gestational age at sampling from 4.3 per cent before 9 weeks to 0.4 per cent at or after 13 weeks, the difference being statistically significant (p <0.025). The fetal loss rate increased from 1.6 per cent in women under 30 to 2.4 per cent in women of 40 years or over, but the difference was not statistically significant. Considering that the total fetal loss rate before 28 weeks' gestation was on average 1.91 percent (1.3 per cent under 35 years and 2.8 per cent in women of 35 or over), we believe that TA-CVS is a safe and effective technique for prenatal diagnosis of genetic diseases.  相似文献   
78.
In this report we have summarized our experience with the prenatal diagnosis of β-thalassemia in 1000 pregnancies followed at least until 12 months after birth. In the majority of these cases, the thalassemia lesion was the nonsense mutation at the codon corresponding to amino acid 39, which produces the hematological phenotype of β-thalassemia. Fetal blood sampling was carried out by placental aspiration, by which a sufficient amount of fetal blood for analysis was obtained in the majority of cases (99 per cent). The fetal mortality associated with fetal blood sampling was 6·3 per cent. Those placental samples contaminated by maternal cells were successfully purified by Ørskov lysis. Fetal blood was analysed by globin chain synthesis on CM–52 columns, which gave reliable results. Two misdiagnoses (0·2 per cent) have been made of which one was due to a non-globin protein co-migrating with the β-chains while the other resulted from a misclassification of the type of thalassemia segregating in the family.  相似文献   
79.
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号