全文获取类型
收费全文 | 2117篇 |
免费 | 82篇 |
国内免费 | 85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 | 453篇 |
皮肤病学 | 7篇 |
神经病学 | 394篇 |
特种医学 | 122篇 |
外科学 | 182篇 |
综合类 | 21篇 |
预防医学 | 125篇 |
眼科学 | 6篇 |
药学 | 316篇 |
中国医学 | 1篇 |
肿瘤学 | 103篇 |
出版年
2023年 | 12篇 |
2022年 | 27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2284条查询结果,搜索用时 15 毫秒
1.
Qian Zhang Larry D. Mesner Gina M. Calabrese Naomi Dirckx Zhu Li Angela Verardo Qian Yang Robert J. Tower Marie-Claude Faugere Charles R. Farber Thomas L. Clemens 《The Journal of clinical investigation》2021,131(7)
Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture. GWAS have identified hundreds of loci influencing BMD, but few have been functionally analyzed. In this study, we show that SNPs within a BMD locus on chromosome 14q32.32 alter splicing and expression of PAR-1a/microtubule affinity regulating kinase 3 (MARK3), a conserved serine/threonine kinase known to regulate bioenergetics, cell division, and polarity. Mice lacking Mark3 either globally or selectively in osteoblasts have increased bone mass at maturity. RNA profiling from Mark3-deficient osteoblasts suggested changes in the expression of components of the Notch signaling pathway. Mark3-deficient osteoblasts exhibited greater matrix mineralization compared with controls that was accompanied by reduced Jag1/Hes1 expression and diminished downstream JNK signaling. Overexpression of Jag1 in Mark3-deficient osteoblasts both in vitro and in vivo normalized mineralization capacity and bone mass, respectively. Together, these findings reveal a mechanism whereby genetically regulated alterations in Mark3 expression perturb cell signaling in osteoblasts to influence bone mass. 相似文献
2.
A growing body of data suggests that therapies based on Toll-like receptors (TLR) targeting, in particular TLR4, holds promise in curing autoimmune and inflammatory pathologies still lacking specific treatment, included several rare diseases. While TLR4 activators (agonists) have already found successful clinical application as vaccine adjuvants, the use of TLR4 blockers (antagonists) as antisepsis agents or as agents against inflammatory diseases (including arthritis, multiple sclerosis, neuroinflammations) and cancer is still at a preclinical phase of development. This minireview focuses on recent achievements on the development of TLR4 modulators based on lipid A structure simplification, in particular on compounds having disaccharide or monosaccharide structures. As the TLR4 activity of natural TLR4 ligands (lipopolysaccharide, LPS and its biologically active part, the lipid A) depends on both the structure of endotoxin aggregates in solution and on single-molecule interaction with MD-2 and CD14 receptors, the rational design of TLR4 modulators should in principle take into account both these factors. In the light of the most recent advances in the field, in this minireview we discuss the structure–activity relationship in simplified lipid A analogs, with cationic or anionic amphiphilic structures. 相似文献
3.
4.
5.
Ketai LH; Williamson MR; Telepak RJ; Levy H; Koster FT; Nolte KB; Allen SE 《Radiology》1994,191(3):665
6.
7.
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
8.
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
9.
10.
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