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   9105篇
  免费   490篇
  国内免费   89篇
耳鼻咽喉   34篇
儿科学   191篇
妇产科学   156篇
基础医学   1321篇
口腔科学   211篇
临床医学   517篇
内科学   2289篇
皮肤病学   367篇
神经病学   839篇
特种医学   329篇
外科学   1325篇
综合类   27篇
预防医学   198篇
眼科学   98篇
药学   693篇
中国医学   21篇
肿瘤学   1068篇
  2023年   45篇
  2022年   40篇
  2021年   177篇
  2020年   96篇
  2019年   132篇
  2018年   177篇
  2017年   181篇
  2016年   201篇
  2015年   202篇
  2014年   274篇
  2013年   331篇
  2012年   562篇
  2011年   628篇
  2010年   368篇
  2009年   306篇
  2008年   526篇
  2007年   613篇
  2006年   576篇
  2005年   577篇
  2004年   551篇
  2003年   584篇
  2002年   551篇
  2001年   168篇
  2000年   132篇
  1999年   163篇
  1998年   145篇
  1997年   100篇
  1996年   91篇
  1995年   92篇
  1994年   83篇
  1993年   75篇
  1992年   103篇
  1991年   104篇
  1990年   78篇
  1989年   93篇
  1988年   48篇
  1987年   70篇
  1986年   56篇
  1985年   59篇
  1984年   40篇
  1983年   26篇
  1982年   31篇
  1981年   18篇
  1980年   28篇
  1979年   38篇
  1978年   19篇
  1977年   17篇
  1976年   16篇
  1975年   17篇
  1974年   17篇
排序方式: 共有9684条查询结果,搜索用时 78 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.
7.
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   
8.
9.
Purpose: Evaluate therapeutic results of transcatheter segmental hepatic artery chemo-oily-embolization (segmental TAE) against advanced hepatocellular carcinomas (HCC) accompanied by portal tumor thrombus (PTT). Methods: Segmental TAE was performed in nine patients with hepatic cirrhosis and advanced HCCs accompanied by PTT. Four subsegmental portal branches were obstructed by PTT in three patients, and two were obstructed in the remaining six patients. TAE was performed into the targeted segmental hepatic artery followed by embolization with gelatin sponge particles. Results: In one patient undergoing subsequent resection, a marked anticancer effect on the PTT was demonstrated histologically. In the eight other patients who did not undergo subsequent resection, the cumulative survival rates were 67% at 6 months, 44% at 1 year, and 22% at 2 years. No serious complications were noted. Conclusions: This therapeutic approach is thought to be a useful treatment for HCC with PTT, because it reinforces anticancer effects and can be performed more safely than conventional transcatheter arterial embolization.  相似文献   
10.
The purpose of this paper is to describe our recent experience in performing laparoscopic cholecystectomies of which we performed 1904, from January 1991 to May 1997, at our private hospital, mainly to treat cholecystolithiasis. The patients included 1563 with gallbladder stones (82.0%), 82 with cholecystocholedocholithiasis (4.3%), 104 with adenomyomatosis (5.5%), 132 with polyps (6.9%), and 23 with gallbladder cancer (1.3%). A difficult pericholecystic dissection led to conversion to open surgery in 61 patients. The average operation time was 63 min. Bile duct injury or cystic artery bleeding occurred in 3 patients with acute cholecystitis, and small intestine injury occurred in 1 patient, while bile leakage or a right subphrenic abscess occurred in 6 patients postoperatively. Although this series included 69 patients with previous upper abdominal surgery, 14 with liver cirrhosis, 267 with a nonvisualized gallbladder, and 148 with acute cholecystitis, the overall conversion rate was only 3.2% and morbidity only 0.5%. Although almost all patients with cholelithiasis are now considered potential candidates for a laparoscopic cholecystectomy, difficulties during cholecystectomy have been encountered in patients with acute cholecystitis. Surgeons should thus be fully prepared to convert to open surgery whenever difficulties are encountered, in order to avoid complication.  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