全文获取类型
收费全文 | 1764篇 |
免费 | 256篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 24篇 |
儿科学 | 126篇 |
妇产科学 | 28篇 |
基础医学 | 193篇 |
口腔科学 | 59篇 |
临床医学 | 189篇 |
内科学 | 417篇 |
皮肤病学 | 36篇 |
神经病学 | 74篇 |
特种医学 | 226篇 |
外科学 | 135篇 |
综合类 | 109篇 |
预防医学 | 235篇 |
眼科学 | 13篇 |
药学 | 108篇 |
中国医学 | 3篇 |
肿瘤学 | 94篇 |
出版年
2023年 | 17篇 |
2022年 | 16篇 |
2021年 | 33篇 |
2020年 | 28篇 |
2019年 | 20篇 |
2018年 | 26篇 |
2017年 | 46篇 |
2016年 | 48篇 |
2015年 | 37篇 |
2014年 | 75篇 |
2013年 | 92篇 |
2012年 | 61篇 |
2011年 | 62篇 |
2010年 | 90篇 |
2009年 | 78篇 |
2008年 | 59篇 |
2007年 | 87篇 |
2006年 | 64篇 |
2005年 | 61篇 |
2004年 | 48篇 |
2003年 | 28篇 |
2002年 | 30篇 |
2001年 | 52篇 |
2000年 | 44篇 |
1999年 | 28篇 |
1998年 | 88篇 |
1997年 | 69篇 |
1996年 | 70篇 |
1995年 | 56篇 |
1994年 | 53篇 |
1993年 | 47篇 |
1992年 | 31篇 |
1991年 | 17篇 |
1990年 | 29篇 |
1989年 | 32篇 |
1988年 | 35篇 |
1987年 | 30篇 |
1986年 | 33篇 |
1985年 | 32篇 |
1984年 | 17篇 |
1983年 | 21篇 |
1982年 | 20篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 14篇 |
1976年 | 19篇 |
1975年 | 19篇 |
1974年 | 10篇 |
1970年 | 10篇 |
排序方式: 共有2069条查询结果,搜索用时 15 毫秒
1.
By injecting small amounts of CO2 through a needle, one can move bowel or bladder from the intended path of instruments during interventional procedures. The technique worked well in six of seven cases in the pelvis and retroperitoneum; it was not effective in the mediastinum or midabdomen (n = 6). 相似文献
2.
The complex enterprise of modelling prenatal exposure to cigarettes: what is ‘enough’? 总被引:1,自引:0,他引:1
Kate E. Pickett Paul J. Rathouz Vanja Dukic Kristen Kasza Marina Niessner Rosalind J. Wright Lauren S. Wakschlag 《Paediatric and perinatal epidemiology》2009,23(2):160-170
While there is a burgeoning body of research linking smoking during pregnancy to problem behaviour in offspring, a major criticism of this work has been the crude measurement of exposure in these studies (e.g. retrospective, self-reported only) that could lead to biased estimates. To address this issue, we used a pregnancy cohort with repeated prospective measures of exposure as well as biological assays to generate estimates of exposure patterns using a range of modelling techniques. In this paper we report on the analytical approaches we have developed, including patterns of exposure over time and best-estimate approaches that combine self-report and cotinine measures, and compare their predictive value in relation to different dimensions of fetal growth as a first step towards examining the utility of greater precision of exposure measurement.
Surprisingly, in this sample the more complex assessments of exposure, including biological measures, generally did not perform better than simple indicators of exposure based on repeated self-report measures, with one exception: a combined self-report cotinine 'best estimate' of third trimester exposure was uniquely associated with lower brain : body ratio. Further study is needed using more sophisticated cotinine assays and testing prediction of a range of outcomes to ascertain whether these findings represent true differences or are specific to the sample, methods and outcomes used. Such research will inform the development of guidelines for adequate exposure characterisation in developmental studies. 相似文献
Surprisingly, in this sample the more complex assessments of exposure, including biological measures, generally did not perform better than simple indicators of exposure based on repeated self-report measures, with one exception: a combined self-report cotinine 'best estimate' of third trimester exposure was uniquely associated with lower brain : body ratio. Further study is needed using more sophisticated cotinine assays and testing prediction of a range of outcomes to ascertain whether these findings represent true differences or are specific to the sample, methods and outcomes used. Such research will inform the development of guidelines for adequate exposure characterisation in developmental studies. 相似文献
3.
外科医生和手术室人员经常接触手术设备产生的烟气,病人也会暴露于烟气中,特别是腹腔镜手术中产生的烟气滞留于腹腔内这一密闭空间并被吸收.这些烟气是一种与香烟烟气相似的毒性物质,然而对这种毒性物质的影响还未引起足够重视.应该采取必要措施尽可能减少手术中烟气的不良影响. 相似文献
4.
5.
6.
7.
8.
9.
10.