全文获取类型
收费全文 | 553篇 |
免费 | 41篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 25篇 |
儿科学 | 8篇 |
基础医学 | 65篇 |
口腔科学 | 7篇 |
临床医学 | 37篇 |
内科学 | 79篇 |
皮肤病学 | 3篇 |
神经病学 | 19篇 |
特种医学 | 241篇 |
外科学 | 39篇 |
综合类 | 5篇 |
预防医学 | 15篇 |
眼科学 | 3篇 |
药学 | 14篇 |
肿瘤学 | 40篇 |
出版年
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 21篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 17篇 |
2007年 | 21篇 |
2006年 | 18篇 |
2005年 | 13篇 |
2004年 | 9篇 |
2003年 | 3篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 20篇 |
1997年 | 21篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1994年 | 22篇 |
1993年 | 21篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 25篇 |
1988年 | 24篇 |
1987年 | 27篇 |
1986年 | 19篇 |
1985年 | 21篇 |
1984年 | 28篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1981年 | 19篇 |
1980年 | 16篇 |
1979年 | 6篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有600条查询结果,搜索用时 15 毫秒
1.
2.
Over the last 40 years, the prevalence of smoking in the United States has declined from a peak of approximately 40% in 1965
to 20.9% in 2005. However, the rate of decline has leveled in recent years such that between 2004 and 2005 there was no decline
in smoking prevalence. The prevalence of smoking varies across subpopulations. Among adults, smoking prevalence is currently
highest among those aged 18 to 24 years (24.4%) and those aged 25 to 44 years (24.1%). Women are less likely to smoke than
men; however, the gender gap has narrowed over time. In immigrant populations, smoking prevalence increases with acculturation.
Although smoking prevalence varies widely by state, most states have had a decline over time. Rural populations have a higher
smoking prevalence than urban populations. If further reductions in the prevalence of smoking are to occur, vigilance and
targeted interventions in specific subpopulations will be crucial. 相似文献
3.
4.
Normal and diseased isolated lungs: high-resolution CT 总被引:8,自引:0,他引:8
5.
Picotamide inhibition of excess in vitro thromboxane B2 release by colorectal mucosa in inflammatory bowel disease. 总被引:1,自引:0,他引:1
Collins CE Benson MJ Burnham WR Rampton DS 《Alimentary pharmacology & therapeutics》1996,10(3):315-320
BACKGROUND: Inflammatory bowel disease is associated with increased mucosal release of eicosanoids. Among these, thromboxane A2 has been proposed as a possible inflammatory mediator; its suppression may be a useful therapeutic option. METHODS: Using a tissue incubation technique, we compared release of immunoreactive thromboxane B2 by colonic biopsies from patients with ulcerative colitis, Crohn's disease and controls, and assessed the inhibitory effect of picotamide, a thromboxane synthesis inhibitor-receptor antagonist, which has been widely used in Italy for management of ischaemic heart and cerebrovascular disease. RESULTS: Increased amounts of thromboxane B2 were released from biopsies from patients with active ulcerative colitis (median 238 pg/20 min/mg wet weight (interquartile range 147- 325), n = 12) and active Crohn's disease (252 (174-450), 6) compared with those from patients with quiescent ulcerative colitis (95 (61- 140), 12) or Crohn's disease (105 (57-201), 13), or controls (136 (64- 206), 8). Incubation with picotamide at concentrations between 100 microM and 1 mM reduced thromboxane B2 release (IC50 890 microM). CONCLUSION: Since increased thromboxane A2 production may have pathogenetic importance, thromboxane synthesis inhibitor-receptor antagonists such as picotamide merit therapeutic trial in the management of inflammatory bowel disease. 相似文献
6.
7.
8.
Hydrosalpinges adversely affect markers of endometrial receptivity 总被引:22,自引:10,他引:22
Meyer WR; Castelbaum AJ; Somkuti S; Sagoskin AW; Doyle M; Harris JE; Lessey BA 《Human reproduction (Oxford, England)》1997,12(7):1393-1398
While in-vitro fertilization (IVF) was initially developed in women with
tubal factor infertility, recent clinical studies have suggested that the
presence of hydrosalpinges lowers implantation and pregnancy rates. We
postulated that these hydrosalpinges cause impaired endometrial
receptivity. A total of 103 women with hydrosalpinges were prospectively
evaluated, and compared with 55 infertile and 44 fertile controls. All
women had endometrial biopsies during the window of implantation, analysed
by conventional histological criteria, and also stained for three integrin
markers of endometrial receptivity (alpha1beta1, alpha4beta1 and alpha
vbeta3). Women with hydrosalpinges (cases) expressed significantly less of
the alpha vbeta3 integrin compared with controls. There was no difference
in expression of alpha1beta1 or alpha4beta1 among groups. A significantly
greater number of cases had out of phase histology and missing alpha vbeta3
(type I defects) and absent integrin expression despite normal histological
maturation (type II) defects, compared with controls. Of 20 women with
impaired endometrial receptivity who were also biopsied after hydrosalpinx
surgery, 70% demonstrated increased alpha vbeta3 expression. Seventy-seven
percent of type I and 57% of type II defects were corrected
postoperatively. Using markers of endometrial receptivity, this study
demonstrates that inflammatory hydrosalpinges have an adverse effect on
endometrial receptivity, which in some cases may be overcome by surgical
treatment of the hydrosalpinx.
相似文献
9.
10.
Association of DLG5 R30Q variant with inflammatory bowel disease 总被引:6,自引:0,他引:6
Daly MJ Pearce AV Farwell L Fisher SA Latiano A Prescott NJ Forbes A Mansfield J Sanderson J Langelier D Cohen A Bitton A Wild G Lewis CM Annese V Mathew CG Rioux JD 《European journal of human genetics : EJHG》2005,13(7):835-839
Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory diseases of the gastrointestinal system known as the inflammatory bowel diseases (IBD). Recently, Stoll and colleagues reported a novel finding of genetic variation in the DLG5 gene that is associated with IBD (CD and UC combined). We present here a study of the genetic variation described in that report in two well-powered, independent case-control cohorts and one family-based collection, and confirm the proposed association between IBD and the R30Q variant of DLG5 in two of the three studies. We are, however, unable to replicate the other proposed association to the common haplotype described in Stoll et al and suggest that this other finding could conceivably have been partially a statistical fluctuation and partially a result of LD with the replicated R30Q association. This study provides support for the hypothesis that DLG5 constitutes a true IBD risk factor of modest effect. 相似文献