全文获取类型
收费全文 | 102654篇 |
免费 | 7525篇 |
国内免费 | 376篇 |
专业分类
耳鼻咽喉 | 1128篇 |
儿科学 | 2531篇 |
妇产科学 | 1649篇 |
基础医学 | 14501篇 |
口腔科学 | 2192篇 |
临床医学 | 10482篇 |
内科学 | 21768篇 |
皮肤病学 | 1803篇 |
神经病学 | 10914篇 |
特种医学 | 4226篇 |
外国民族医学 | 6篇 |
外科学 | 14674篇 |
综合类 | 1252篇 |
一般理论 | 73篇 |
预防医学 | 7930篇 |
眼科学 | 1725篇 |
药学 | 6913篇 |
中国医学 | 111篇 |
肿瘤学 | 6677篇 |
出版年
2023年 | 573篇 |
2022年 | 1085篇 |
2021年 | 2149篇 |
2020年 | 1319篇 |
2019年 | 1971篇 |
2018年 | 2425篇 |
2017年 | 1787篇 |
2016年 | 2135篇 |
2015年 | 2479篇 |
2014年 | 3265篇 |
2013年 | 4306篇 |
2012年 | 6657篇 |
2011年 | 6710篇 |
2010年 | 3963篇 |
2009年 | 3610篇 |
2008年 | 5929篇 |
2007年 | 6426篇 |
2006年 | 5961篇 |
2005年 | 5902篇 |
2004年 | 5514篇 |
2003年 | 4925篇 |
2002年 | 4875篇 |
2001年 | 1868篇 |
2000年 | 1795篇 |
1999年 | 1663篇 |
1998年 | 1215篇 |
1997年 | 996篇 |
1996年 | 807篇 |
1995年 | 815篇 |
1994年 | 695篇 |
1993年 | 635篇 |
1992年 | 1152篇 |
1991年 | 1069篇 |
1990年 | 1011篇 |
1989年 | 971篇 |
1988年 | 865篇 |
1987年 | 813篇 |
1986年 | 832篇 |
1985年 | 827篇 |
1984年 | 671篇 |
1983年 | 582篇 |
1982年 | 552篇 |
1981年 | 453篇 |
1980年 | 394篇 |
1979年 | 517篇 |
1978年 | 411篇 |
1977年 | 369篇 |
1975年 | 334篇 |
1974年 | 361篇 |
1973年 | 351篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A total of 143 patients with superficial G2 (pTa, pT1) bladder cancer (48 G2pTa; 95 G2pT1) presenting between 1970 through 1987 were reviewed. Of 48 patients with G2pTa followed for up to eighteen years, G3 recurrence developed only in 1 (2.0%), and invasive cancer (greater than pT2) developed only in 2 (4.2%). They both received radiotherapy and have responded completely. There have been no cancer-related deaths. In contrast, in the 95 patients in whom the basement membrane had been breached (pT1), higher grade tumor (G3) developed in 11 (11.5%), and 15 (16%) had recurrences with invasion of muscle (greater than pT2). Among these there were 7 (7.3%) cancer-related deaths. 相似文献
62.
63.
Lamiya Samad Chris Hollis Martin Prince Robert Goodman 《International journal of methods in psychiatric research》2005,14(4):230-230
The original article to which this Erratum refers was published in International Journal of Methods in Psychiatric Research, 2005; Vol.14, No.3, 158–166. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
64.
Martin Williams 《Transfusion and apheresis science》2007,36(2):213-214
65.
66.
67.
68.
Objectives: To investigate the effect of the type instrumentation used and the age and gender characteristics of patients on postoperative haemorrhage rates following tonsil and adenoid surgery. Design: A retrospective analysis of 13 593 procedures was performed from The Patient Episode Database for Wales between 1 January 1999 and 31 March 2004. Setting: National health policy changes created four periods of different instrument usage (reusable, single‐use with diathermy, single‐use alone, specified single‐use with diathermy). These and the age and gender distribution of the patients were examined against four categories of postoperative haemorrhage. Main outcome measures: Postoperative haemorrhage rates were expressed as the number of complications per operations performed. Primary postoperative haemorrhage that occurred during the initial admission either required a return to theatre [R1] or was managed conservatively [N1]; secondary postoperative haemorrhage that required a return to hospital either returned to theatre [R2] or was managed conservatively [N2], were compared. Results: Primary haemorrhage with return to theatre doubled, from the baseline rate with reusable instruments, from 0.6% (CI 0.5–0.8) to 1.2% (CI 0.7–1.9) when single‐use instruments were introduced and remained high at 1.4% (CI 0.9–2.1) after the withdrawal of single‐use diathermy. This haemorrhage rate returned to the baseline rate (0.6% CI 0.3–1.0) when specified single‐use instruments were introduced. None of the other haemorrhage rates changed significantly throughout the four observation periods. Adenotonsillectomy and tonsillectomy patients have different age and gender patterns. In a univariate analysis, males over the age of 12 years were twice as likely to have haemorrhage with return to theatre than girls of the same age, 3.8% (CI 3.0–4.7) versus 1.7% (CI 1.4–2.1). Conclusions: A significant rise in serious postoperative primary haemorrhage but not secondary haemorrhage was seen following the initial introduction of single‐use instruments that reverted to baseline with the introduction of specified single‐use instruments. Diathermy does not appear to have affected the haemorrhage rates. There is a distinct age and gender pattern for tonsil and adenoid surgery and risk of postoperative haemorrhage. The use of arbitrary divisions of age may be misleading in studies that examine post‐tonsillectomy haemorrhage. 相似文献
69.
Martin Tepel 《Nephrology, dialysis, transplantation》2003,18(8):1439-1442
Reactive oxygen species: general aspects Reactive oxygen species, including superoxide radicals, hydrogenperoxide, nitric oxide, peroxynitrite, hydroxyl radicals andhypochlorous acid are by-products of normal metabolic processesin cells. Reactive oxygen species can be found in several cellsincluding macrophages and vascular smooth muscle cells. At lowconcentrations reactive oxygen species can act as physiologicalmediators of cellular responses whereas higher concentrationsmay cause cell damage [1,2]. The major sources of reactive oxygenspecies are leakages from the electron transport chains of mitochondriaand endoplasmic reticulum. Cellular energy metabolism is basedon the production of ATP through the electron transport reactionin which O2 accepts electrons and H+ and then is eventuallyreduced to water. Only 12% of the electrons are leakedto generate superoxide radicals in reactions mediated by coenzymeQ and ubiquinone and its complexes. During ageing (and probablyin patients 相似文献
70.
The regioselective reaction of aliphatic ω-isocyanatoacyl chlorides with silyl-protected hydroxy-nucleophiles was extended to aromatic isocyanatoacyl chlorides. Starting with 3- or 4-isocyanatobenzoyl chloride and 3- or 4-trimethylsiloxyphenyl isocyanate, the four isomeric isocyanatobenzoic acid isocyanatophenyl esters were synthesized in high yields. From terephthaloyl chloride and two moles of a siloxyphenyl isocyanate or from 1,4-bis(trimethylsiloxybenzene) and two moles of an isocyanatobenzoyl chloride, diesterdiisocyanates were obtained containing 3 benzene rings. The para-substituted diisocyanates show liquid-crystalline behaviour. Polyaddition reaction with various diols led to poly(esterurethane)s with a regular sequence of urethane and ester groups. The poly(urethane)s from the para-substituted diisocyanates have very high melting points (225–350°C). Liquid crystallinity could not be proven unambiguously due to the instability of the urethane linkage at these temperatures. 相似文献