全文获取类型
收费全文 | 2350424篇 |
免费 | 171234篇 |
国内免费 | 3332篇 |
专业分类
耳鼻咽喉 | 32052篇 |
儿科学 | 75896篇 |
妇产科学 | 62690篇 |
基础医学 | 348194篇 |
口腔科学 | 63638篇 |
临床医学 | 211359篇 |
内科学 | 457314篇 |
皮肤病学 | 51729篇 |
神经病学 | 185285篇 |
特种医学 | 88026篇 |
外国民族医学 | 489篇 |
外科学 | 353896篇 |
综合类 | 47511篇 |
现状与发展 | 12篇 |
一般理论 | 848篇 |
预防医学 | 182755篇 |
眼科学 | 54328篇 |
药学 | 175130篇 |
11篇 | |
中国医学 | 4575篇 |
肿瘤学 | 129252篇 |
出版年
2021年 | 18992篇 |
2019年 | 19544篇 |
2018年 | 27068篇 |
2017年 | 20369篇 |
2016年 | 22748篇 |
2015年 | 25649篇 |
2014年 | 36099篇 |
2013年 | 53958篇 |
2012年 | 74691篇 |
2011年 | 79415篇 |
2010年 | 47062篇 |
2009年 | 44568篇 |
2008年 | 74617篇 |
2007年 | 79487篇 |
2006年 | 80307篇 |
2005年 | 77787篇 |
2004年 | 74373篇 |
2003年 | 71699篇 |
2002年 | 69375篇 |
2001年 | 108742篇 |
2000年 | 111455篇 |
1999年 | 93502篇 |
1998年 | 26990篇 |
1997年 | 23658篇 |
1996年 | 24054篇 |
1995年 | 22716篇 |
1994年 | 20895篇 |
1993年 | 19714篇 |
1992年 | 72001篇 |
1991年 | 70076篇 |
1990年 | 68395篇 |
1989年 | 65669篇 |
1988年 | 60307篇 |
1987年 | 59131篇 |
1986年 | 55223篇 |
1985年 | 53007篇 |
1984年 | 39313篇 |
1983年 | 33396篇 |
1982年 | 19860篇 |
1979年 | 35869篇 |
1978年 | 25651篇 |
1977年 | 21230篇 |
1976年 | 20336篇 |
1975年 | 21817篇 |
1974年 | 26150篇 |
1973年 | 24804篇 |
1972年 | 23204篇 |
1971年 | 22037篇 |
1970年 | 20252篇 |
1969年 | 19317篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
Julie A. Schmidt Georgina K. Fensom Sabina Rinaldi Augustin Scalbert Paul N. Appleby David Achaintre Audrey Gicquiau Marc J. Gunter Pietro Ferrari Rudolf Kaaks Tilman Kühn Heiner Boeing Antonia Trichopoulou Anna Karakatsani Eleni Peppa Domenico Palli Sabina Sieri Rosario Tumino Bas Bueno-de-Mesquita Antonio Agudo Maria-Jose Sánchez María-Dolores Chirlaque Eva Ardanaz Nerea Larrañaga Aurora Perez-Cornago Nada Assi Elio Riboli Konstantinos K. Tsilidis Timothy J. Key Ruth C. Travis 《International journal of cancer. Journal international du cancer》2020,146(3):720-730
Metabolomics may reveal novel insights into the etiology of prostate cancer, for which few risk factors are established. We investigated the association between patterns in baseline plasma metabolite profile and subsequent prostate cancer risk, using data from 3,057 matched case–control sets from the European Prospective Investigation into Cancer and Nutrition (EPIC). We measured 119 metabolite concentrations in plasma samples, collected on average 9.4 years before diagnosis, by mass spectrometry (AbsoluteIDQ p180 Kit, Biocrates Life Sciences AG). Metabolite patterns were identified using treelet transform, a statistical method for identification of groups of correlated metabolites. Associations of metabolite patterns with prostate cancer risk (OR1SD) were estimated by conditional logistic regression. Supplementary analyses were conducted for metabolite patterns derived using principal component analysis and for individual metabolites. Men with metabolite profiles characterized by higher concentrations of either phosphatidylcholines or hydroxysphingomyelins (OR1SD = 0.77, 95% confidence interval 0.66–0.89), acylcarnitines C18:1 and C18:2, glutamate, ornithine and taurine (OR1SD = 0.72, 0.57–0.90), or lysophosphatidylcholines (OR1SD = 0.81, 0.69–0.95) had lower risk of advanced stage prostate cancer at diagnosis, with no evidence of heterogeneity by follow-up time. Similar associations were observed for the two former patterns with aggressive disease risk (the more aggressive subset of advanced stage), while the latter pattern was inversely related to risk of prostate cancer death (OR1SD = 0.77, 0.61–0.96). No associations were observed for prostate cancer overall or less aggressive tumor subtypes. In conclusion, metabolite patterns may be related to lower risk of more aggressive prostate tumors and prostate cancer death, and might be relevant to etiology of advanced stage prostate cancer. 相似文献
142.
143.
144.
145.
Christopher N. Cooley Tyler J. Beranek Matthew A. Warpinski Robert Alexander Amanda O. Esquivel 《The American journal of emergency medicine》2019,37(2):199-203
Introduction
In the United States there has been a large increase in participation in lacrosse for both males and females. The purpose of this study was to analyze the number of head injuries, injury rates (calculated using the reported number of participants) and types of head injuries that are seen in emergency departments in the United States.Methods
We compared injuries between male and female lacrosse participants. This was a retrospective study using a publicly available database produced by the US Consumer Product Safety Commission and information about lacrosse participation from US Lacrosse.Results
A linear regression was performed and showed a positive correlation between number of head injuries to males and time from 2002 to 2010 (R2?=?0.823; p?=?0.001). While the number of injuries to the head in female lacrosse participants was not significant. There was a negative correlation between the number of head injuries to males from 2010 to 2016 (R2?=?0.800; p?=?0.007), but again, there was no significance for female injury count (R2?=?0.417; p?=?0.117). Other significant differences between head injuries in males and females included the mechanism of injury and the type of injury recorded.Conclusion
The most recent data from 2010 to 2016, suggest that both males and females have had a decrease in injury rate. However the total number of female head injuries is not significantly decreasing and as the sport continues to grow there will likely be more total head injuries and visits to the emergency department. 相似文献146.
147.
Saleem A. Banihani 《Basic & clinical pharmacology & toxicology》2016,118(1):9-13
Histamine‐2 receptor antagonists are a class of drugs used to treat the acid‐related gastrointestinal diseases such as ulcer and gastro‐oesophageal reflux disease. Although such drugs, especially ranitidine and famotidine, are still widely used, their effects on semen quality, and hence on male infertility, is still unclear. This MiniReview systematically addresses and summarizes the effect of histamine‐2 receptor antagonists (cimetidine, ranitidine, nizatidine and famotidine) on semen quality, particularly, on sperm function. Cimetidine appears to have adverse effects on semen quality. While the effects of ranitidine and nizatidine on semen quality are still controversial, famotidine does not appear to change semen quality. Therefore, additional studies will be required to clarify whether histamine‐2 receptor‐independent effects of these drugs play a role in semen quality as well as further clinical studies including direct comparison of the histamine‐2 receptor antagonists. 相似文献
148.
149.
D. Sforza G. Iaria L. Petagna A. Parente A. Anselmo F. Sergi S. Marzio F. Corrado S. Telli T.M. Manzia G. Tisone 《Transplantation proceedings》2019,51(1):140-142
Background
One daily dose of tacrolimus (QDT) improves adherence in kidney transplant (KT) recipients. A switch from twice-daily tacrolimus (BDT) to QDT showed similar efficacy and safety.Methods
The aim of our study was to demonstrate the long-term efficacy and safety of switching from BDT to QDT in KT recipients. Preliminary results have already been published. Forty-one patients (34 men and 7 women), mean age at KT of 43.9 ± 12.7 years, underwent a 1:1 dose switch from BDT to QDT; the mean time from KT to switch was 36.6 ± 16.1 months. In our study population, 4 patients received a living donor KT and 2 received a second allograft.Results
The mean follow-up was 86.8 ± 13 months from the switch and 126.2 ± 22.3 months from KT. Graft and patient survival rates were 90.2% and 95.1%, respectively. All patients maintained stable renal function during follow-up. During the first 3 months after the switch we observed a significant decrease in tacrolimus blood level (P = .0001). No significant differences were observed regarding tacrolimus dose before and after QDT introduction (P = not significant [NS]). Fourteen patients who stopped steroids under BDT treatment and 16 patients who stopped steroids after the switch are currently steroid-free.Conclusion
Our study showed safety and efficacy in switching from BDT to QDT. After early (<1 year) dose adjustment, tacrolimus blood levels remained stable throughout follow-up. Moreover, QDT represented a valid alternative for patients showing steroid side effects. 相似文献150.