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   3372篇
  免费   212篇
  国内免费   26篇
耳鼻咽喉   50篇
儿科学   57篇
妇产科学   12篇
基础医学   433篇
口腔科学   63篇
临床医学   227篇
内科学   791篇
皮肤病学   74篇
神经病学   391篇
特种医学   122篇
外科学   635篇
综合类   17篇
预防医学   68篇
眼科学   33篇
药学   304篇
中国医学   2篇
肿瘤学   331篇
  2023年   56篇
  2022年   96篇
  2021年   160篇
  2020年   75篇
  2019年   117篇
  2018年   115篇
  2017年   106篇
  2016年   102篇
  2015年   133篇
  2014年   141篇
  2013年   145篇
  2012年   213篇
  2011年   215篇
  2010年   134篇
  2009年   121篇
  2008年   162篇
  2007年   172篇
  2006年   158篇
  2005年   134篇
  2004年   124篇
  2003年   119篇
  2002年   103篇
  2001年   60篇
  2000年   53篇
  1999年   45篇
  1998年   34篇
  1997年   20篇
  1996年   14篇
  1995年   18篇
  1994年   15篇
  1993年   27篇
  1992年   55篇
  1991年   50篇
  1990年   51篇
  1989年   36篇
  1988年   36篇
  1987年   38篇
  1986年   32篇
  1985年   21篇
  1984年   23篇
  1983年   16篇
  1982年   8篇
  1981年   9篇
  1979年   8篇
  1977年   11篇
  1976年   5篇
  1975年   7篇
  1974年   3篇
  1973年   3篇
  1971年   2篇
排序方式: 共有3610条查询结果,搜索用时 31 毫秒
1.
From April 1989 to December 2004, we performed liver biopsy on 475 patients and obtained biopsy proven 35 cases of non-alcoholic fatty liver. Among them, 18 cases were diagnosed as non-alcoholic steatohepatitis (NASH). During the last three years, we have tried to detect NASH using ultrasonography and elevated value of serum ferritin (> 300 ng/ml). All of the eligible 7 cases biopsied during the course were diagnosed as NASH. In these 7 cases, ALT levels improved after the body weight loss accompanied by the parallel decrease of serum ferritin levels. Measurement of serum ferritin is useful in the detection of NASH but the normal value of ferritin cannot rule out the possibility of NASH.  相似文献   
2.
A 50-year-old man with the symptom of anal pain was treated by pelvic exenteration, ileal conduit diversion and artificial anus. The pathologic diagnosis was leiomyosarcoma of the prostate. At 5 months post-operatively, the patient had no evidence of metastasis or recurrence.  相似文献   
3.
In order to estimate the diagnostic validity of chemical fecal occult blood tests, i.e. orthotolidine (Shionogi A) and guajac (Shionogi B) slides for detecting cancers of the esophagus, stomach and colorectum, the authors followed up all the examinees (n=3,449) of comprehensive medical check-ups at the Center for Adult Diseases, Osaka, by means of record linkage to the Osaka Cancer Registry's files. Then, diagnostic validity was calculated based on the results of two years' follow-up. Sensitivity for the respective cancers was 20.0%, 11.8% and 62.5% for Shionogi A, and 20.0%, 5.9% and 43.8% for Shionogi B slides. Likelihood ratio for the respective cancers was 1.4, 0.8 and 4.5 for Shionogi A, and 3.3, 1.0 and 7.5 for Shionogi B. Specificity was analogous among the three cancer sites, being 86% for Shionogi A and 94% for Shionogi B. These results suggest that the diagnostic validity of chemical occult blood tests for detecting cancers of the esophagus and the stomach is very poor, and therefore imply that close examinations of these sites for screening positives is unnecessary in mass screenings for colorectal cancer.  相似文献   
4.
We investigated the involvements of sympathetic and nonadrenergic nervous systems in the inhibitory reflex following bronchoconstriction in dogs. Inhalations of a 0.00125% solution of histamine and Ascaris suum antigen (3 mg protein) to the bronchial side induced reflex tracheal constriction following bronchoconstriction. An intra-arterial infusion of 5 micrograms/min of atropine to the tracheal site changed the reflex tracheal constrictions by histamine and antigen inhalations into tracheal dilatations. The reflex tracheal dilatations were abolished by the combination of intra-arterial propranolol (100 micrograms) and transections of both the bilateral superior laryngeal nerves and the spinal cord at the C1 level. The reflex tracheal constrictions induced by histamine and antigen inhalations were increased with 100 micrograms propranolol. Furthermore, the reflex tracheal constrictions were enhanced by the combination of 100 micrograms propranolol and transection of the spinal cord. These findings indicate that during the constriction of the bronchial smooth muscle, not only a reflex tracheal constriction mechanism but also one of reflex dilatation operates and that the latter reflex response may be mainly mediated by the sympathetic nerves, with partial involvement of the nonadrenergic nerves. This inhibitory reflex may attenuate asthmatic bronchoconstriction.  相似文献   
5.
While nonspecific airway hyperresponsiveness (AHR) is a central feature of allergic bronchial asthma, the mechanism underlying the development of AHR is not clearly understood. We have previously demonstrated in vitro hyperresponsiveness of bronchial smooth muscle to acetylcholine (ACh) in rats that were actively sensitized and repeatedly challenged with aerosolized antigen. It has also been demonstrated that the ACh-induced, RhoA-mediated Ca(2+) sensitization is markedly augmented concomitantly with an increased expression and activation of RhoA protein in the bronchial smooth muscle of the antigen-treated rats. In the present study, we have investigated whether TNF-alpha, a proinflammatory cytokine which is involved in bronchial asthma, causes upregulation of RhoA mRNA and protein in the rat bronchus. Treatment of rat bronchial smooth muscle preparations with TNF-alpha (300 ng/ml for 24 hr) significantly shifted the concentration-response curve to ACh upwards, but did not alter the response to high K(+), when compared to that of control tissues. Levels of RhoA mRNA and protein in the TNF-alpha-treated bronchus were significantly greater than those in the control group. In conclusion, it is suggested that the augmentation of the ACh-induced contractile response evoked by TNF-alpha might be mediated by an upregulation of RhoA in rat bronchial smooth muscle.  相似文献   
6.
7.
Tissue renin content within the kidney decreases from outer to inner cortex. However, it is not known whether this gradient is due to a decrease in the number of afferent arterioles from the outer to inner cortex or the decrease in renin content per afferent arteriole. Furthermore, it is still controversial whether sodium depletion increases or decreases this gradient. According to Taugner et al., sodium depletion induces the extension of renin positive part of afferent arterioles from vascular pole toward interlobular artery. Since the length of extension may differ among superficial, midcortical, and juxtamedullary afferent arterioles, the observed gradient may vary depending on whether the entire afferent arteriole or only the vascular pole is examined. In the present study, we microdissected the entire afferent arterioles from superficial, middle, and juxtamedullary cortex of rabbit kidney, and examined tissue renin content. We studied: 1. whether tissue renin content per afferent arteriole decreases from the outer to inner cortex. 2. whether sodium depletion affects the gradient of tissue renin content within the cortex. In result, we reached the conclusions, as follows: 1. Tissue renin content per afferent arteriole decreases steeply from superficial to midcortical to juxtamedullary afferent arterioles. 2. The absolute difference in renin content among the three types of afferent arterioles becomes greater during sodium depletion. The internephron heterogeneity of tissue renin content may contribute to functional heterogeneity.  相似文献   
8.
Following cardiac surgery, approximation of sternum will produce systemic hypotension or elevation of left atrial and central venous pressures. A new criteria for delayed sternal closure is proposed. Sternal closure has to be delayed when mean left atrial or central venous pressures increased over 2 mmHg at the tentative closure. In seven cases (3.5%) of consecutive 201 patients was delayed the sternal closure under the above mentioned state, all survived and received the successful closure later. One of them died of congestive heart failure four months after the operation and one died of the rupture of the ascending aortic pseudoaneurysm eleven months after the initial operation. Microbiological examination of the mediastinal and pericardial contents obtained at the final sternal closure were negative in all cases. Comparing the total cardiopulmonary bypass time, ventricular fibrillation time, and myocardial ischemic time between in the secondary closure group and in the primary closure group, the total bypass time and the ventricular fibrillation time of the former were significantly longer than the latter, but the ischemic time revealed no difference. In conclusions, persistent elevation of left atrial or central venous pressures after cardiac surgery at the tentative sternal closure seems the reliable predictor for the delayed closure of the sternum. Careful post-operative management prevents serious mediastinal infection. Delayed sternal closure is preferable procedure for the patient with brittle hemodynamics after open heart surgery.  相似文献   
9.
10.
The results of repairing cleft lip by aesthetic plastic surgery are now excellent. However, the cleft lipnose deformity is still very difficult to repair with the present techniques. A technique that can repair the cleft lip-nose deformity with good results is presented. The technique is divided into three parts: Part I consists of nasal repair of the primary cleft lip. Part II is nasal reconstruction as a secondary operation with or without lip repair. For example, nasal reconstruction may be secondary to repair of deformities of the sill, rim, limen nasi, septum, or nasal bones. Part III is an aesthetic nasal operation such as rhinoplasty, mentoplasty, or zygomaplasty.  相似文献   
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