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   449篇
  国内免费   84篇
耳鼻咽喉   53篇
儿科学   154篇
妇产科学   197篇
基础医学   1301篇
口腔科学   318篇
临床医学   551篇
内科学   2163篇
皮肤病学   485篇
神经病学   754篇
特种医学   291篇
外科学   1327篇
综合类   24篇
预防医学   207篇
眼科学   106篇
药学   637篇
中国医学   27篇
肿瘤学   1043篇
  2023年   32篇
  2022年   81篇
  2021年   179篇
  2020年   90篇
  2019年   125篇
  2018年   180篇
  2017年   189篇
  2016年   197篇
  2015年   207篇
  2014年   288篇
  2013年   326篇
  2012年   548篇
  2011年   601篇
  2010年   356篇
  2009年   282篇
  2008年   496篇
  2007年   564篇
  2006年   563篇
  2005年   573篇
  2004年   562篇
  2003年   555篇
  2002年   557篇
  2001年   141篇
  2000年   135篇
  1999年   161篇
  1998年   148篇
  1997年   97篇
  1996年   88篇
  1995年   87篇
  1994年   77篇
  1993年   62篇
  1992年   101篇
  1991年   101篇
  1990年   96篇
  1989年   97篇
  1988年   68篇
  1987年   83篇
  1986年   62篇
  1985年   61篇
  1984年   43篇
  1983年   34篇
  1982年   34篇
  1981年   29篇
  1980年   25篇
  1979年   44篇
  1978年   24篇
  1974年   17篇
  1972年   24篇
  1969年   23篇
  1968年   17篇
排序方式: 共有9638条查询结果,搜索用时 218 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.
A case of an odontogenic tumor which invaded the intracranial space from the mandible is reported. Judging from the radiographic images it was similar to a malignant tumor. The patient died 17 years after the first visit. According to the final pathological diagnosis, it was malignant odontogenic mixed tumor of low grade which did not belong to any of the WHO classification.  相似文献   
9.
Summary Utilizing two types of human renal carcinoma heterotransplanted in nude mice, we investigated the variations in hyperthermic effects (42.5°C for 30 min) caused by differences in tumor type with special reference to variations in tumor vascularity. In the hypovascular JRC1 strain, sporadic vascular dilation was observed throughout the tumors after heating. Destruction of tumor cells was observed mainly in the region of dilation. In the hypervascular JRC11 strain, homogenous vascular dilation was observed immediately after heating, mainly at the periphery of tumors. There was a decrease in the viability of cells in the center of the tumor. Therefore, the hypervascular tumors showed greater destruction mainly at the center where blood circulation was reduced. The range of necrosis was also greatly affected by the extent of vascular dilation caused by heating in hypovascular tumors.  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