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   8851篇
  免费   457篇
  国内免费   81篇
耳鼻咽喉   66篇
儿科学   165篇
妇产科学   157篇
基础医学   1336篇
口腔科学   176篇
临床医学   569篇
内科学   2216篇
皮肤病学   270篇
神经病学   702篇
特种医学   367篇
外科学   1306篇
综合类   32篇
预防医学   230篇
眼科学   105篇
药学   625篇
中国医学   21篇
肿瘤学   1046篇
  2023年   40篇
  2022年   116篇
  2021年   177篇
  2020年   96篇
  2019年   126篇
  2018年   186篇
  2017年   172篇
  2016年   194篇
  2015年   207篇
  2014年   281篇
  2013年   316篇
  2012年   525篇
  2011年   602篇
  2010年   342篇
  2009年   286篇
  2008年   501篇
  2007年   586篇
  2006年   571篇
  2005年   570篇
  2004年   544篇
  2003年   588篇
  2002年   544篇
  2001年   154篇
  2000年   123篇
  1999年   154篇
  1998年   151篇
  1997年   99篇
  1996年   85篇
  1995年   90篇
  1994年   80篇
  1993年   66篇
  1992年   89篇
  1991年   85篇
  1990年   93篇
  1989年   78篇
  1988年   58篇
  1987年   61篇
  1986年   42篇
  1985年   50篇
  1984年   25篇
  1983年   22篇
  1982年   26篇
  1981年   17篇
  1980年   16篇
  1979年   22篇
  1978年   14篇
  1977年   12篇
  1976年   12篇
  1974年   14篇
  1967年   10篇
排序方式: 共有9389条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Mutations in the gene encoding 11beta-hydroxysteroid dehydrogenase type 2, HSD11B2, cause a rare monogenic juvenile hypertensive syndrome called apparent mineralocorticoid excess (AME). In AME, defective HSD11B2 enzyme activity results in overstimulation of the mineralocorticoid receptor (MR) by cortisol, causing sodium retention, hypokalemia, and salt-dependent hypertension. Here, we have studied whether genetic variations in HDS11B2 are implicated in essential hypertension in Japanese hypertensives and the general population. By sequencing the entire coding region and the promoter region of HDS11B2 in 953 Japanese hypertensives, we identified five missense mutations in 11 patients (L14F, n = 5; R74H, n = 1; R147H, n = 3; T156I, n = 1; R335H, n = 1) and one novel frameshift mutation (4884Gdel, n = 1) in a heterozygous state, in addition to 19 genetic variations. All genetic variations identified were rare, with minor allele frequencies less than 0.005. Four of 12 patients with the missense/frameshift mutations showed renal failure. Four missense mutations, L14F, R74H, R147H, and R335H, were successfully genotyped in the general population, with a sample size of 3,655 individuals (2,175 normotensives and 1,480 hypertensives). Mutations L14F, R74H, R147H, and R335H were identified in hypertensives (n = 6, 8, 3, and 0, respectively) and normotensives (n = 8, 12, 5, and 0, respectively) with a similar frequency, suggesting that these missense mutations may not strongly affect the etiology of essential hypertension. Since the allele frequency of all of the genetic variations identified in this study was rare, an association study was not conducted. Taken together, our results indicate that missense mutations in HSD11B2 do not substantially contribute to essential hypertension in Japanese.  相似文献   
5.
The Trk family of tyrosine protein kinase receptors plays a significant role in the development and maintenance of neural tissues. It has been recently shown that Trk receptors are also expressed by a wide range of normal non-neuronal tissues in humans in a cell type-specific manner. In the present study, the expression patterns of TrkA in 337 non-neuronal invasive carcinomas of 15 different human tissues were investigated immunohistochemically. Overall, 133 (39%), 101 (30%) and 103 (31%) tumors exhibited strong, moderate and no TrkA Immunoreactivity, respectively. Esophageal and thyroid carcinomas expressed high levels of TrkA, whereas the levels in gastric and colon cancers were low. TrkA expression was detected not only in carcinomas originating from TrkA-positive normal counterpart tissues, Including the esophagus, breast, lung and uterus, but also in those from TrkA-negative tissues/cells of the thyroid, liver and ovary. Immunostaining for nerve growth factor-β, the specific ligand for TrkA, in esophageal and breast carcinomas demonstrated its immunoreactivity in stromal fibroblasts and some TrkA-expressing tumor cells. These results suggest that paracrine/autocrine regulation via stromal/tumoral NGF-tumoral TrkA interaction may be involved In the growth of certain non-neuronal carcinomas.  相似文献   
6.
The patient responded to treatment at the first onset of heart failure but gradually became irresponsive to treatment, experiencing fatigue and malaise as the chief complaints and suffering from gradually progressive decrease in exercise capacity and body weight. Dose of DOA gradually increased to maintain well clinical state of the patient. Unusual for heart failure, he had bradycardia as the basal rhythm without showing a tendency for tachycardia. Cardiac catheterization revealed pulmonary hypertension and low cardiac output, however, left ventricular ejection fraction was 37%. There were no notable changes in ultrasonic cardiogram or CTR through the clinical course. Tl-201 myocardial images and pulmonary perfusion images showed gradual worsening corresponding to progressive worsening of clinical state. From these findings, the patient was determined as a candidate for heart transplantation.  相似文献   
7.
8.
Objective To establish a means for prenatal prediction of spinal muscular atrophy (SMA) through survival motor neuron (SMN) gene deletion analysis and genetic counseling in families with a child affected with SMA.
Methods
Genetic analysis for prenatal prediction of Werdnig-Hoffmann disease was performed in a at risk Chinese family by polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) in SMN gene exons 7 and 8.
Results The pregnancy was positive for the homozygous deletion of the SMN gene, thus the fetus was diagnosed as being affected and the pregnancy was terminated.
Conclusion This approach is fast and reliable for DNA-based prenatal diagnosis of Werdnig-Hoffmann disease.  相似文献   
9.
Surgical treatment for subacute pulmonary arterial thromboembolism has previously been considered to be inappropriate. We undertook a pulmonary arterial thrombectomy and removal of a floating right heart thrombus in a patient who had been symptomatic for over a month. The pulmonary arterial pressure, which had been equal to the systemic pressure preoperatively, decreased gradually and almost normalized one month postoperatively. Pulmonary perfusion scintigraphy revealed a dramatic improvement and the patient returned to normal life activities.  相似文献   
10.
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