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   3632篇
  免费   198篇
  国内免费   8篇
耳鼻咽喉   39篇
儿科学   64篇
妇产科学   48篇
基础医学   502篇
口腔科学   43篇
临床医学   445篇
内科学   804篇
皮肤病学   32篇
神经病学   356篇
特种医学   90篇
外科学   426篇
综合类   20篇
一般理论   1篇
预防医学   335篇
眼科学   95篇
药学   276篇
中国医学   1篇
肿瘤学   261篇
  2023年   23篇
  2022年   47篇
  2021年   79篇
  2020年   46篇
  2019年   46篇
  2018年   52篇
  2017年   45篇
  2016年   76篇
  2015年   97篇
  2014年   115篇
  2013年   148篇
  2012年   227篇
  2011年   267篇
  2010年   132篇
  2009年   176篇
  2008年   260篇
  2007年   294篇
  2006年   311篇
  2005年   304篇
  2004年   224篇
  2003年   213篇
  2002年   180篇
  2001年   26篇
  2000年   20篇
  1999年   23篇
  1998年   44篇
  1997年   33篇
  1996年   39篇
  1995年   22篇
  1994年   24篇
  1993年   38篇
  1992年   13篇
  1991年   11篇
  1990年   12篇
  1989年   12篇
  1988年   15篇
  1987年   8篇
  1986年   12篇
  1984年   5篇
  1983年   11篇
  1982年   9篇
  1981年   5篇
  1980年   11篇
  1979年   5篇
  1973年   4篇
  1943年   3篇
  1940年   3篇
  1935年   4篇
  1932年   8篇
  1931年   3篇
排序方式: 共有3838条查询结果,搜索用时 0 毫秒
41.
    
  相似文献   
42.
Since most hip fractures are related to osteoporosis, treating accelerated bone loss can be an important strategy to prevent hip fractures. Thiazides have been associated with reduced age-related bone loss by decreasing urinary calcium excretion.  相似文献   
43.
44.
45.
Previous fMRI studies of sensorimotor activation in schizophrenia have found in some cases hypoactivity, no difference, or hyperactivity when comparing patients with controls; similar disagreement exists in studies of motor laterality. In this multi-site fMRI study of a sensorimotor task in individuals with chronic schizophrenia and matched healthy controls, subjects responded with a right-handed finger press to an irregularly flashing visual checker board. The analysis includes eighty-five subjects with schizophrenia diagnosed according to the DSM-IV criteria and eighty-six healthy volunteer subjects. Voxel-wise statistical parametric maps were generated for each subject and analyzed for group differences; the percent Blood Oxygenation Level Dependent (BOLD) signal changes were also calculated over predefined anatomical regions of the primary sensory, motor, and visual cortex. Both healthy controls and subjects with schizophrenia showed strongly lateralized activation in the precentral gyrus, inferior frontal gyrus, and inferior parietal lobule, and strong activations in the visual cortex. There were no significant differences between subjects with schizophrenia and controls in this multi-site fMRI study. Furthermore, there was no significant difference in laterality found between healthy controls and schizophrenic subjects. This study can serve as a baseline measurement of schizophrenic dysfunction in other cognitive processes.

Graphical Abstract

相似文献   
46.
Schwannomatosis is characterized by the development of multiple non-vestibular, non-intradermal schwannomas. Constitutional inactivating variants in two genes, SMARCB1 and, very recently, LZTR1, have been reported. We performed exome sequencing of 13 schwannomatosis patients from 11 families without SMARCB1 deleterious variants. We identified four individuals with heterozygous loss-of-function variants in LZTR1. Sequencing of the germline of 60 additional patients identified 18 additional heterozygous variants in LZTR1. We identified LZTR1 variants in 43% and 30% of familial (three of the seven families) and sporadic patients, respectively. In addition, we tested LZTR1 protein immunostaining in 22 tumors from nine unrelated patients with and without LZTR1 deleterious variants. Tumors from individuals with LZTR1 variants lost the protein expression in at least a subset of tumor cells, consistent with a tumor suppressor mechanism. In conclusion, our study demonstrates that molecular analysis of LZTR1 may contribute to the molecular characterization of schwannomatosis patients, in addition to NF2 mutational analysis and the detection of chromosome 22 losses in tumor tissue. It will be especially useful in differentiating schwannomatosis from mosaic Neurofibromatosis type 2 (NF2). However, the role of LZTR1 in the pathogenesis of schwannomatosis needs further elucidation.  相似文献   
47.
BACKGROUND/AIMS: Currently, there are no effective therapies available for patients with chronic hepatitis C who have failed to respond to optimal interferon alfa-based regimens. The aims of this pilot study were to assess the antiviral activity and safety of interferon gamma in chronic hepatitis C. METHODS: Patients with chronic hepatitis C, genotype 1, who had not responded to or who had relapsed after therapy with interferon alfa and ribavirin were enrolled in a trial of interferon gamma 1b given in doses of 100, 200 or 400 microg subcutaneously three times weekly for 4 weeks. Frequent blood samples were obtained for HCV RNA levels. RESULTS: Fourteen patients were enrolled. Geometric mean HCV RNA levels remained unchanged. Serum aminotransferase levels also did not change, while there were significant decreases in neutrophil counts (-41% from baseline) and hematocrit (-5%). Low grade fever and malaise were common with the first injection of interferon gamma, but no serious side effects were encountered. CONCLUSIONS: Although relatively well tolerated, interferon gamma in doses of 100-400 microg thrice weekly had no effect on HCV RNA levels in patients with chronic hepatitis C who had failed to achieve a sustained response to interferon alfa-based therapies.  相似文献   
48.
49.
Journal of Thrombosis and Thrombolysis - We present a novel case of a patient with nephrotic syndrome and previous left pneumonectomy who had a massive pulmonary embolism of his remnant right...  相似文献   
50.
Human IgG4 antibodies are remarkable not only because they can dynamically exchange half-molecules (Fab-arm exchange) but also for their ability to interact with the Fc part of IgG4 and other IgG subclasses. This rheumatoid factor-like binding of IgG4 does not appear to take place spontaneously, because it is only observed to solid-phase or antigen-bound IgG. We hypothesized that Fc-Fc interactions might involve (partial) dissociation of heavy chains. We investigated the molecular basis of these Fc-Fc interactions, and found that the structural features important for the exchange reaction also control the Fc binding activity. In particular, if arginine-409 in the CH(3)-CH(3) interface in IgG4 is mutated to lysine (the equivalent in IgG1), Fc-Fc interactions are formed 3 orders of magnitude less efficiently compared to the wild-type. This mutation was previously found to increase the CH(3)-CH(3) interaction strength in IgG4. Furthermore, of the two hinge isomers of IgG4, the intra-chain (non-covalently linked) form was found to form Fc-Fc interactions, but not the inter-chain form. Together, these results demonstrate that Fc-Fc interactions of IgG4 involve (partial or complete) dissociation of heavy chains. The promiscuity to other IgG subclasses suggests that IgG4 might act as scavenger to IgG molecules with impaired structural integrity.  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