全文获取类型
收费全文 | 5794篇 |
免费 | 104篇 |
国内免费 | 78篇 |
专业分类
安全科学 | 229篇 |
废物处理 | 275篇 |
环保管理 | 1322篇 |
综合类 | 1057篇 |
基础理论 | 1203篇 |
环境理论 | 5篇 |
污染及防治 | 1291篇 |
评价与监测 | 356篇 |
社会与环境 | 188篇 |
灾害及防治 | 50篇 |
出版年
2021年 | 51篇 |
2020年 | 32篇 |
2019年 | 60篇 |
2018年 | 77篇 |
2017年 | 101篇 |
2016年 | 112篇 |
2015年 | 118篇 |
2014年 | 114篇 |
2013年 | 576篇 |
2012年 | 205篇 |
2011年 | 274篇 |
2010年 | 209篇 |
2009年 | 214篇 |
2008年 | 277篇 |
2007年 | 280篇 |
2006年 | 258篇 |
2005年 | 192篇 |
2004年 | 213篇 |
2003年 | 219篇 |
2002年 | 192篇 |
2001年 | 91篇 |
2000年 | 111篇 |
1999年 | 101篇 |
1998年 | 84篇 |
1997年 | 68篇 |
1996年 | 77篇 |
1995年 | 85篇 |
1994年 | 73篇 |
1993年 | 74篇 |
1992年 | 78篇 |
1991年 | 48篇 |
1990年 | 58篇 |
1989年 | 51篇 |
1988年 | 34篇 |
1987年 | 40篇 |
1986年 | 48篇 |
1985年 | 45篇 |
1984年 | 49篇 |
1983年 | 54篇 |
1982年 | 39篇 |
1981年 | 58篇 |
1980年 | 48篇 |
1979年 | 30篇 |
1978年 | 34篇 |
1963年 | 25篇 |
1960年 | 23篇 |
1959年 | 24篇 |
1955年 | 27篇 |
1954年 | 33篇 |
1951年 | 24篇 |
排序方式: 共有5976条查询结果,搜索用时 46 毫秒
71.
Aris Antsaklis John Politis Costas Karagiannopoulos Dionysios Kaskarelis Photini Karababa John Panourgias Marina Boussiou Dimitris Loukopoulos 《黑龙江环境通报》1984,4(4):289-296
Selective feticide is the procedure of choice when, in twin binovular pregnancy, only one of the fetuses is shown to be affected. As the probabilities for this condition are almost 1:2 when the genetic disease is due to homozygosity for two autosomal recessive genes, the problem is expected to occur frequently among the ever increasing number of couples seeking prenatal diagnosis of thalassaemia and the haemoglobinopathies. The present report is the first case of this condition and the ninth in the overall medical literature. 相似文献
72.
Diana W. Bianchi MD Gretchen K. Zickwolf Melissa C. Yih Alan F. Flint Ossie H. Geifman Marlena S. Erikson John M. Williams 《黑龙江环境通报》1993,13(4):293-300
Fetal nucleated erythrocytes (NRBC) in maternal blood are a non-invasive source of fetal DNA for prenatal genetic screening. We compared the effectiveness of three monoclonal antibodies for the separation of fetal cells from maternal blood by flow sorting. Mononuclear blood cells from 49 healthy pregnant women were incubated with antibody to CD 71, CD 36, and/or glycophorin A (GPA), employed singly or in combination with each other. These monoclonal antibodies recognize surface antigens on haematopoietic precursor cells. Successful isolation of fetal cells was defined as detection of Y chromosomal sequences in maternal blood from women carrying male fetuses, with absence of Y sequences when female fetuses were carried. Thus, gender prediction accuracy was used as a measure of fetal cell separation. Using anti-CD 71 to isolate fetal cells, gender prediction was 57 per cent correct; with anti-CD 36, it was 88 per cent correct. Anti-GPA, an erythrocyte-specific antigen, used alone or in combination with anti-CD 71 or 36, improved gender prediction to 100 per cent. We conclude that antibody to GPA improves the retrieval of fetal NRBC from maternal blood, permitting genetic analysis by the polymerase chain reaction. 相似文献
73.
Data from 2907 transcervical CVS cases performed on singleton pregnancies were reviewed retrospectively and villus sample size was correlated with cytogenetic results, placental location, maternal age at the expected date of confinement (EDC), gestational age at the time of sampling, birth weight, gestational age at the time of delivery, and pregnancy outcome. No correlation was noted between villus sample size and maternal age, gestational age at sampling, gestational age at delivery, birth weight, or pregnancy outcome. An inverse correlation between villus sample size and percentage of abnormal cytogenetic findings was statistically significant (X2 = 8·53, p <0·01). The percentage of small samples was greater when the placenta was anterior, lateral, or fundal than when the placenta was posterior. 相似文献
74.
75.
76.
John C. Eccles 《Die Naturwissenschaften》1979,66(3):147-153
Synaptic plasticity is manifested by long-lasting changes in synaptic potency. Increased potency is of special importance in relation to the neural basis of memory. Even mild repetitive stimulation evokes large and prolonged potentiations of hippocampal synapses, as is revealed by electrical recording either in vivo or in vitro. More importantly there is a matching hypertrophy of the synaptic spines on the dendrites of hippocampal granule cells, as is shown by most convincing electronmicrographs. The increase is to about 40% some 2 h after a mild stimulation (900 impulses) and there was relatively little decline by 23 h. There is brief reference to the metabolic processes that could be involved in this plastic response. 相似文献
77.
78.
79.
80.