首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   183312篇
  免费   1543篇
  国内免费   79篇
耳鼻咽喉   1190篇
儿科学   6826篇
妇产科学   3084篇
基础医学   17374篇
口腔科学   1723篇
临床医学   12864篇
内科学   33203篇
皮肤病学   1033篇
神经病学   16816篇
特种医学   9278篇
外科学   30208篇
综合类   2346篇
一般理论   1篇
预防医学   18213篇
眼科学   2800篇
药学   9848篇
中国医学   633篇
肿瘤学   17494篇
  2023年   151篇
  2022年   300篇
  2021年   475篇
  2020年   231篇
  2019年   316篇
  2018年   22217篇
  2017年   17634篇
  2016年   19782篇
  2015年   1226篇
  2014年   1230篇
  2013年   1184篇
  2012年   7653篇
  2011年   21652篇
  2010年   19143篇
  2009年   11782篇
  2008年   19924篇
  2007年   22158篇
  2006年   989篇
  2005年   2593篇
  2004年   3703篇
  2003年   4572篇
  2002年   2677篇
  2001年   329篇
  2000年   455篇
  1999年   231篇
  1998年   238篇
  1997年   243篇
  1996年   118篇
  1995年   121篇
  1994年   114篇
  1993年   80篇
  1992年   99篇
  1991年   131篇
  1990年   165篇
  1989年   110篇
  1988年   86篇
  1987年   67篇
  1986年   46篇
  1985年   51篇
  1984年   28篇
  1983年   38篇
  1982年   29篇
  1980年   42篇
  1974年   27篇
  1969年   24篇
  1938年   60篇
  1937年   25篇
  1934年   30篇
  1932年   56篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Previously reported attenuation of skin postural vasoconstriction in women during the luteal menstrual cycle phase may be due to a progesterone-mediated decrease in myogenic or veno-arteriolar (VAR) mechanisms. Skin perfusion was measured in the shin and foot dorsum by Laser Doppler Fluxometry during leg dependency that increased vascular transmural pressure below (myogenic constriction only) and above (myogenic and VAR) the 25 mmHg threshold for activation of the VAR, and during venous distension to activate the VAR alone (cuff inflation to 50 mmHg). In six young women with normal menstrual cycles, vasoconstrictor responses to all interventions did not differ between days 7–13 (follicular) and 18–23 (luteal) of the normal menstrual cycle when progesterone levels were low and at their peak respectively. In eight women taking combined oral contraceptives (OC) and tested during pill consumption days, reductions in foot skin perfusion were smaller (P = 0.05) than in the luteal phase of the normal cycle for leg dependency below (−36.9 ± 5.2% OC vs. −52.5 ± 7.8% luteal, mean ± S.E.M.) and above (−43.7 ± 3.4% OC vs. −55.1 ± 4.8% luteal) the VAR threshold, and for venous distension (−53.1 ± 2.6% OC vs. 66.4 ± 5.5% luteal). In women with normal menstrual cycles, impaired postural vasoconstriction may be confined to those who experience pre-menstrual symptoms rather than a direct effect of endogenous hormones. Reduced vasoconstriction in the dependent foot during OC use is consistent with the known vasodilator action of exogenous hormones and its long-term effects  相似文献   
102.
Stenosis of the hypopharyngo-oesophageal junction can be a rare complication of laryngectomy and/or partial pharyngectomy and makes the insertion of voice prosthesis extremely difficult. This study describes the authors’ experiences gained by endoscopic balloon-catheter dilatation of hypopharyngo-oesophageal stenoses prior to implantation of voice prostheses in four cases. In two patients a single balloon-catheter dilatation resulted in wide enough pharyngo-oesophageal lumen on the long run. The average prosthesis wearing-times were 6.8 months in case 1 and 4.6 months in case 2, corresponding to the published literature data. In case 3, repeated dilatation of the pharyngo-oesophageal transition had proved to be unsuccessful despite taking every effort with the endoscopic balloon-catheter method. Having excised the stenotic segment, reconstruction with pectoralis major myocutaneous flap (PMMF) was indicated. Eighteen months later, a repeated restenosis was observed and a free jejunal flap needed to be performed as a final solution. In case 4, the insertion was carried out into a previously dilated jejunal free flap, which became gradually ischemic and stenotic since the major head-and neck procedure was carried out that resulted in prosthesis rejection after just 1 week. The authors emphasize that correct indication of pedicled and free flaps in head and neck reconstruction is a prerequisite from the aspect of prevention of pharyngo-oesophageal strictures. Endoscopic balloon-catheter dilatation is a safe and established method for dilatating hypopharyngo-oesophageal stenoses of different origin. The procedure provides maximum patient benefit with minimal trauma and morbidity; moreover, facilitates insertion of voice prostheses. However, a single balloon-catheter dilatation cannot always result in wide enough oesophageal lumen on the long run (case 3). Insertion of a voice prosthesis into a previously dilated ischemic jejunal segment is challenging and avoidable due to risks of complications.  相似文献   
103.
Background Sympathectomy is the treatment of choice for primary hyperhidrosis. One curious occurrence that is difficult to explain from an anatomophysiological point of view in cases of video-assisted thoracoscopic sympathectomy (VATS) for the treatment of palmar hyperhidrosis (PH) is the observed improvement in plantar hyperhidrosis (PLH). Nevertheless, current reports on VATS rarely describe the effect on PLH or just give superficial data. The aim of this study was to prospectively investigate, how surgery affects PLH in patients with PH and PLH over one-year period. Methods From May 2003 to January 2004, 70 consecutive patients with combined PH and PLH underwent VATS at the T2, T3, or T4 ganglion level (47 women and 23 men, with mean age of 23 years). Results Immediately after the operation, all the patients said they were free from PH episodes, except for two patients (2.8%) who suffered from continued PH. Compensatory hyperhidrosis (CH) of various degrees was observed in 58 (90.6%) patients after one year. Only 13 (20.3%) suffered from severe CH. There was a great initial improvement in PLH in 50% of the cases, followed by progressive regression, such that only 23.4% still presented that improvement after one year. The number of cases without overall improvement increased progressively (from 17.1% to 37.5%) and the numbers with slight improvement remained stable (32.9–39.1%). Of the 24 patients with no improvement after one year, 6 patients graded plantar sweating worse. Conclusion Patients with PH and PLH who undergo VATS to treat their PH present a good initial improvement in PLH that reduces to a lower level of improvement after the one-year period.  相似文献   
104.
Epiploic appendagitis and omental infarction: pitfalls and look-alikes   总被引:3,自引:0,他引:3  
Epiploic appendagitis and omental infarction are benign self-limiting conditions that are more frequent than generally assumed. Both disorders frequently mimic symptoms of an abdominal surgical emergency, often leading to clinical misdiagnosis of appendicitis or diverticulitis. Because a misdiagnosis can result in an unnecessary laparotomy, a correct diagnosis is of great importance. Ultrasound and computed tomography can be used to make a reliable diagnosis. This pictorial essay illustrates the various ultrasonographic and computed tomographic appearances of epiploic appendagitis and omental infarction and focuses on their radiologic differential diagnoses and pitfalls. Received: 22 February 2001/Accepted: 18 April 2001  相似文献   
105.
Background: Although managed care organizations (MCOs) may be optimal settings for implementing tobacco use cessation clinical guidelines, such guidelines remain poorly implemented in many MCO settings.Purpose: We examined issues related to the implementation of guidelines in MCOs, to provide examples of studies that have addressed issues related to guideline implementation and to suggest ways behavioral medicine researchers can play a role in examining issues of how guidelines can be better implemented.Methods: Surveys of clinical guideline implementation, studies from the Robert Wood Johnson Foundation addressing tobacco use cessation in a managed care database, selected to illustrate issues related to system-wide implementation.Results: Surveys show that effective tobacco use cessation interventions remain underutilized in MCOs. A few studies have evaluated and shown the benefit of insurance coverage for tobacco use and dependence treatments, clinician reimbursement and leadership incentives, practice feedback, and leveraging administrative data to create tobacco use tracking systems. The studies also point to the need for large-scale, multidisciplinary, methodologically rigorous studies that allow one to isolate the effects of promising strategies as well as to explore synergistic effects as different system changes are combined.Conclusions: Tobacco use cessation guidelines need to be better implemented in MCOs. Behavioral medicine research needs to move beyond treatment efficacy and effectiveness studies to focus on rigorous evaluations of these and other strategies to enhance guideline implementation and dissemination. This research was supported by grants from the Tobacco-Related Disease Research Program (Taylor) and from the Robert Wood Johnson Foundation (Taylor and Curry).  相似文献   
106.
107.
Ohne Zusammenfassung  相似文献   
108.
109.
110.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号