全文获取类型
收费全文 | 2122篇 |
免费 | 81篇 |
国内免费 | 86篇 |
专业分类
耳鼻咽喉 | 26篇 |
儿科学 | 17篇 |
妇产科学 | 20篇 |
基础医学 | 295篇 |
口腔科学 | 30篇 |
临床医学 | 166篇 |
内科学 | 454篇 |
皮肤病学 | 7篇 |
神经病学 | 395篇 |
特种医学 | 122篇 |
外科学 | 182篇 |
综合类 | 21篇 |
预防医学 | 127篇 |
眼科学 | 6篇 |
药学 | 316篇 |
中国医学 | 1篇 |
肿瘤学 | 104篇 |
出版年
2023年 | 13篇 |
2022年 | 31篇 |
2021年 | 38篇 |
2020年 | 18篇 |
2019年 | 36篇 |
2018年 | 34篇 |
2017年 | 25篇 |
2016年 | 32篇 |
2015年 | 34篇 |
2014年 | 50篇 |
2013年 | 104篇 |
2012年 | 95篇 |
2011年 | 102篇 |
2010年 | 58篇 |
2009年 | 66篇 |
2008年 | 114篇 |
2007年 | 165篇 |
2006年 | 112篇 |
2005年 | 109篇 |
2004年 | 96篇 |
2003年 | 97篇 |
2002年 | 76篇 |
2001年 | 72篇 |
2000年 | 78篇 |
1999年 | 48篇 |
1998年 | 36篇 |
1997年 | 35篇 |
1996年 | 31篇 |
1995年 | 29篇 |
1994年 | 14篇 |
1993年 | 13篇 |
1992年 | 39篇 |
1991年 | 37篇 |
1990年 | 37篇 |
1989年 | 46篇 |
1988年 | 28篇 |
1987年 | 25篇 |
1986年 | 24篇 |
1985年 | 38篇 |
1984年 | 23篇 |
1983年 | 17篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 18篇 |
1979年 | 22篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1970年 | 4篇 |
排序方式: 共有2289条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
Motor-pattern-generating networks in invertebrates have been the objects of intensive study to determine the origin and modulation of rhythmic neural activity. In some pattern generators, intrinsically bursting neurons drive activity throughout the network. In most pattern generators, however, rhythmicity arises from the interplay between intrinsic membrane properties and synaptic interaction. Reciprocal inhibitory synapses between neurons are thought to be crucial for generating oscillation in these networks, but a fundamental understanding of how such network oscillators work remains elusive. Progress towards this goal has come from attempts to combine computational modeling approaches with conventional physiological analysis. 相似文献
5.
Introduction : Hypertrophic scar is a devastating sequel to burns and other tangential skin injuries. It follows deep dermal injuries and does not occur after superficial injuries. Nitric oxide (NO) plays many important roles in wound healing from inflammation to scar remodeling. Studies have shown that expression of nitric oxide synthase and nitric oxide production are decreased in human hypertrophic scar. However little is known about NO involvement in the early stages of hypertrophic scarring, because of the lack of an animal model. It was recently reported that the female red Duroc pig (FRDP) makes thick scar, which is similar to human hypertrophic scar. We hypothesized that NO production in wounds on the female, red Duroc pig is similar to that of human hypertrophic scar and that NO involvement in deep wounds is different from that in superficial wounds. Methods : Superficial (0.015” to 0.030”) and deep (0.045” to 0.060”) wounds were created on the backs of four FRDPs. Biopsies were collected at weeks 1.5, 4, 8 and 21 post wounding including samples of uninjured skin. Nitric oxide levels were measured with the Griess reaction assay and normalized with tissue protein level. Results : Superficial wounds healed with an invisible scar whereas the deep wounds healed with scar resembling mild hypertrophic scar. The thickness of the scars from the deep wounds was significantly greater than uninjured skin and healed superficial wounds (p < 0.01). NO levels were increased at 1.5 weeks in deep wounds compared to superficial wounds and uninjured skin (p < 0.05). At 8 weeks, NO levels in deep wounds had returned to the level of uninjured tissue and superficial wounds. By 21 weeks, NO levels had decreased significantly when compared to superficial wounds (p < 0.01). There were no differences in NO levels between uninjured skin and superficial wounds at any time point (p > 0.05). Conclusions : NO production is similar in late, deep wounds on the female, red Duroc pig to that reported in the literature for human hypertrophic scar further validating this animal model. NO production is quite different after deep wounds as compared to superficial wounds in the FRDP. Early elevation in nitric oxide production might account for excessive inflammation in deep wounds that become thick scars in the FRDP. Nitric oxide regulators and effects at early stages of scar formation should be elucidated further and the FRDP appears to be a useful model. 相似文献
6.
7.
The occurrence of chemically induced hormesis 总被引:5,自引:0,他引:5
This paper will provide an overview of the potential general applicability of chemical hormesis. Evidence will be presented on the occurrence of chemical hormesis by chemical classes studied (e.g. heavy metals, polycylic aromatic hydrocarbons, etc.), by affected biological and toxic end points (e.g. growth enzyme activities, DNA-repair capacity, life span, tumor incidence) and by biological/taxonomic systems. Several specific examples of possible hormetic effects with respect to agents of environmental concern, such as chloroform, will be presented along with a discussion of future research directions. 相似文献
8.
9.
10.
Clustering of Y chromosome deletions in subinterval E of interval 6 supports the existence of an oligozoospermia critical region outside the DAZ gene. 总被引:4,自引:0,他引:4 下载免费PDF全文
L Stuppia V Gatta G Mastroprimiano F Pompetti G Calabrese P Guanciali Franchi E Morizio R Mingarelli M Nicolai R Tenaglia L Improta V Sforza S Bisceglia G Palka 《Journal of medical genetics》1997,34(11):881-883
Y chromosome molecular analysis was performed using the STS-PCR technique in 50 patients with oligozoospermia. Microdeletions of interval 6 of the Y chromosome were detected in seven patients, in six of whom subinterval E was affected. All patients retained the RBM1 and DAZ genes, while in one deletion involved the SPGY gene. The size of the deletion was not apparently related to the severity of the disease. These results suggest the presence of an oligozoospermia critical region on the Y chromosome within subinterval E of interval 6. 相似文献