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   391130篇
  免费   24654篇
  国内免费   2871篇
耳鼻咽喉   5408篇
儿科学   8379篇
妇产科学   10189篇
基础医学   54525篇
口腔科学   12056篇
临床医学   30843篇
内科学   81313篇
皮肤病学   8777篇
神经病学   28509篇
特种医学   14347篇
外国民族医学   82篇
外科学   62319篇
综合类   10021篇
现状与发展   1篇
一般理论   64篇
预防医学   17979篇
眼科学   9767篇
药学   31798篇
  1篇
中国医学   2222篇
肿瘤学   30055篇
  2021年   2838篇
  2019年   2869篇
  2018年   4711篇
  2017年   3582篇
  2016年   3706篇
  2015年   4219篇
  2014年   5962篇
  2013年   7741篇
  2012年   10572篇
  2011年   10828篇
  2010年   6518篇
  2009年   6148篇
  2008年   10054篇
  2007年   10901篇
  2006年   10860篇
  2005年   9963篇
  2004年   9400篇
  2003年   9123篇
  2002年   8792篇
  2001年   28597篇
  2000年   29139篇
  1999年   23953篇
  1998年   5325篇
  1997年   4403篇
  1996年   3954篇
  1995年   3576篇
  1994年   3178篇
  1993年   2919篇
  1992年   16257篇
  1991年   15010篇
  1990年   14348篇
  1989年   14153篇
  1988年   12785篇
  1987年   12227篇
  1986年   11261篇
  1985年   10495篇
  1984年   7036篇
  1983年   5694篇
  1982年   2774篇
  1979年   5547篇
  1978年   3416篇
  1977年   3021篇
  1976年   2296篇
  1975年   2679篇
  1974年   3130篇
  1973年   2927篇
  1972年   2893篇
  1971年   2832篇
  1970年   2558篇
  1969年   2587篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
301.
This study attempted to evaluate the efficacy of chronic extra-aortic counterpulsation with a latissimus dorsi neuro vascular flap. Five dogs had a preliminary procedure consisting of the creation of a latissimus dorsi flap and a thoracotomy in which the flap was wrapped around the descending aorta just distal to the left subclavian artery. An epicardial lead was placed on the left ventricle and a nerve stimulating lead placed around the thoraco-dorsal nerve. Three weeks later, both leads were connected to a cardiomyostimulator programmed to function in a counterpulsation mode with a 1:2 assist frequency. Hemodynamic measurements were made at 6 and 8 and 10 and 12 weeks and the dogs were sacrificed. Three dogs had all sets of hemodynamic measurements made. Two of the three dogs demonstrated diastolic augmentation at 6 and 8 and 10 and 12 weeks average 20 to 25 mmHg. The third dog failed to demonstrate any change. All dogs were sacrificed at 12 weeks and specimens were submitted for histologic evaluation. The muscle flap was preserved in all animals. The aorta subjacent to the flap showed, (1) normal intima with no evidence of disruption or thrombus in all animals, (2) in the animals in whom counterpulsation was observed, there appeared to be thinning of the media in the aorta subjacent to the muscle flap, and (3) no evidence of distal emboli. This study demonstrated that chronic counterpulsation can be obtained with a latissimus dorsi flap. The actual hemodynamic benefits are not determined from this study. The medial thinning in the aortic wall may limit the long-term benefit of this procedure.  相似文献   
302.
The effects of cepharanthin on inflammatory parameters such as neutrophil chemotaxis, phagocytosis and reactive oxygen species (ROS) generation, were examined. Cepharanthin significantly decreased the levels of O2-, H2O2, and OH. generated by neutrophils. H2O2 and OH. generated in a cell-free, xanthine-xanthine oxidase system were also reduced in the presence of cepharanthin. However, the drug did not affect neutrophil chemotaxis or phagocytosis. The present study indicates that cepharanthin is an effective ROS scavenger, exerting its anti-inflammatory action by reducing the potent ROS species excessively generated in tissues and organs, especially at the sites of inflammation.  相似文献   
303.
Deoxycholic acid (DA) caused a dose-related release of histamine (HR) from mast cells of rat peritoneum (RPMC) and mucosal cells of guinea pig rectocolon (RCMC). In both cell populations, DA-induced HR was: (1) accompared by a parallel release of lactate dehydrogenase (LDH), (2) not affected by metabolic inhibitors, (3) dependent on time of incubation, temperature and pH, and affected by Ca++ concentration in RPMC but not in RCMC. DA-induced HR from RCMC may be involved in certain functional disorders of the colon.  相似文献   
304.
Cellular electrophysiological effects of membrane lipid peroxidation by t-butyl hydroperoxide (TBH) were studied in the rabbit sinoatrial (SA) node. Superfusion for 1-5 min with 300 microM TBH caused an initial increase and subsequent decrease in the spontaneous firing frequency of the SA node. Voltage clamp experiments revealed that TBH initially enhanced but later blocked the Ca2+ current. Thus, membrane lipid peroxidation appears to accelerate and then suppress physiological automaticity by causing biphasic changes in the Ca2+ current.  相似文献   
305.
The syndrome of Maffucci is characterized by angioma association of the enchondromatose. It is a relatively rare syndrome. The lesions are evolutived. The treatment is surgical. His pronostic is marqued by high percentage of malign degenerescence.  相似文献   
306.
Endorectal ultrasonography was evaluated in the diagnosis of prostatic cancer, using a high frequency (7,5 MHz) mechanical sectorial endocavitary probe developed by the authors. In a first study, sonograms from a series of 213 patients were interpreted retrospectively without any knowledge of the clinical or pathological findings. Specificity for the diagnosis of cancer (true non-malignant/total non-malignant) reached 79%, whereas sensitivity (true malignant/total malignant) was only 48%. Pathology was available for 132 patients. In a second study, 72 ultrasonically guided biopsies were performed in patients presenting either with a suspicious induration without nodule (47 cases) or a palpable nodule (25 cases). Good quality biopsy specimens, and absence of complication were remarkable. However, the 10 cancer cases (5 diagnosed in each group) did not show sonographically clearly different from the remaining adenoma, prostatitis and normal cases.  相似文献   
307.
Fifty-four patients with 65 superficial malignant lesions were treated by local hyperthermia combined with radiation therapy at the National Cancer Center Hospital, Tokyo. Hyperthermia was delivered with an Aloka Model HMS-020 (2450 MHz) or with a horn-type applicator of BSD-1000 (80-90 MHz). Relatively small tumours, those less than 4 cm in thickness, were treated by using 2450 MHz while 80-90 MHz delivered through the horn-type applicator was used for tumours exceeding 5 cm in thickness. The radiation dose was 4 Gy twice a week or 2 Gy five times a week, the total dose being 40-60 Gy. A total of six to 10 hyperthermia treatments ranging from 40 to 60 min each, with the tumour heated to more than 42.5 degrees C, were given twice a week within 1 h following radiation therapy. Complete response was achieved in 16 of the 30 patients (55 per cent) treated with the 2450 MHz microwave, and partial response in seven others (23 per cent). Tumours treated with the BSD-1000 achieved complete response in 10 out of 33 patients (30 per cent) and partial response in nine others (27 per cent). In five out of nine patients classified as partial responders, however, complete disappearance of tumour cells was noted by post-treatment histological examination. Complete plus partial response rates were thus essentially the same with the Aloka HMS-020 and the BSD-1000, though the rate of complete response was apparently higher with the Aloka unit, probably because it was used on smaller tumours.  相似文献   
308.
309.
The growth of Plasmodium falciparum in erythrocytes from individuals with beta zero-thalassaemia or haemoglobin (Hb) E, or both, was assessed in vitro. A significant inhibitory effect on the growth of the parasite was found only with erythrocytes from individuals doubly heterozygous for beta zeros-thalassaemia and HbE. The inhibitory effect was particularly marked with erythrocytes from splenectomized beta zeros-thalassaemia/HbE patients. The protective effect was related to HbF, Hb levels and shape abnormalities of the variant erythrocytes.  相似文献   
310.
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