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   61935篇
  免费   5549篇
  国内免费   4241篇
耳鼻咽喉   533篇
儿科学   835篇
妇产科学   1077篇
基础医学   7905篇
口腔科学   979篇
临床医学   7929篇
内科学   9869篇
皮肤病学   720篇
神经病学   3731篇
特种医学   2291篇
外国民族医学   52篇
外科学   6315篇
综合类   8265篇
现状与发展   19篇
一般理论   3篇
预防医学   4115篇
眼科学   1766篇
药学   6504篇
  63篇
中国医学   3087篇
肿瘤学   5667篇
  2024年   676篇
  2023年   953篇
  2022年   2397篇
  2021年   3139篇
  2020年   2333篇
  2019年   2159篇
  2018年   2255篇
  2017年   1898篇
  2016年   1909篇
  2015年   2740篇
  2014年   3387篇
  2013年   2885篇
  2012年   4537篇
  2011年   4997篇
  2010年   3014篇
  2009年   2322篇
  2008年   3187篇
  2007年   3238篇
  2006年   3224篇
  2005年   3203篇
  2004年   2182篇
  2003年   2117篇
  2002年   1795篇
  2001年   1266篇
  2000年   1343篇
  1999年   1414篇
  1998年   940篇
  1997年   883篇
  1996年   678篇
  1995年   622篇
  1994年   513篇
  1993年   336篇
  1992年   423篇
  1991年   370篇
  1990年   329篇
  1989年   284篇
  1988年   295篇
  1987年   241篇
  1986年   232篇
  1985年   182篇
  1984年   127篇
  1983年   98篇
  1982年   54篇
  1981年   52篇
  1980年   40篇
  1979年   97篇
  1978年   41篇
  1975年   40篇
  1974年   52篇
  1973年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
We report a 14-year-old boy finally diagnosed with sitosterolemia, presenting with severe aortic valve stenosis. Genetic analysis revealed homozygous null mutation c.1336 C > T (p.R446X) in ABCG5 gene. His cardiac ultrasound presented aortic valve stenosis and moderate aortic regurgitation. His whole aorta computed tomography angiogram scan revealed aortic stenosis superior to the aortic valve, followed by ascending aorta dilation, whereas his coronary and peripheral arteries appeared normal. His maximum total cholesterol and low-density lipoprotein-cholesterol levels dropped dramatically after diet control, and ezetimibe was prescribed for treatment. The current case indicated that sitosterolemia may be a heterogeneous disease in clinical phenotype.  相似文献   
12.
13.
14.
Identification of the association between tissue biomarkers, their surrogates in blood and clinical features, could provide new diagnostic tools and facilitate adequate choices of therapeutic interventions for selected patients suffering from CRS. The aim of present study was the assessment of macrophages in the polyp tissue and monocytes in the peripheral blood in the course of CRSwNP, and their functional immunophenotype. We analyzed 31 patients with CRSwNP. Nasal mucosa tissue was obtained via functional endoscopic sinus surgery (FESS). The control group included 10 patients with deviated nasal septum (DNS). Fluorochrome stained cells were proceed to acquisition using FACS Canto flow cytometer, and the results were analyzed using the software FACS Diva. In our study, we observed a significantly higher level of CD80, CD274, CD273 and TLR1 in nasal polyps compared to blood samples from patients with CRSwNP. This finding may suggest the importance of the PD-1 pathway as a therapeutic target in CRS and an important role for TLR1 in nasal polyp formation and maintenance. Our results may provide some insight into potential future targets of recurrent nasal polyp treatment and contribute to a better understanding of the inflammatory process in Chronic Rhinosinusitis.  相似文献   
15.
16.
Coxsackievirus A16 (CV-A16) commonly causes mild symptoms, but severe diseases, such as aseptic meningitis, encephalitis, and even fatal cases, have been reported. Thirteen CV-A16 strains were isolated from patients with severe hand, foot, and mouth disease in Yunnan, Southwest China, from 2009 to 2015. Subgenotype B1a and B1b of CV-A16 were predominantly circulating the region with B1b the predominant strain in recent years. The mean rate of nucleotide substitution based on the VP1 gene sequence was 4.545 × 10 −3 substitution per site per year from 2009 to 2015. These results may help in understanding the genetic diversity of CV-A16 and develop a CV-A16 vaccine.  相似文献   
17.
The Cluster of differentiation 226(CD226)/T cell immunoglobulin and immune receptor tyrosine-based inhibitory motif domain (TIGIT) axis plays an important role in the balance of the immune response. A previous study showed that CD226 is involved in CD4+ T cell differentiation and that blocking CD226 may attenuate experimental autoimmune encephalomyelitis (EAE) development. However, the molecular mechanisms underlying this process remain incompletely understood. In this study, it was found that Cd226−/− mice were less susceptible to EAE and that there was less T helper 17(Th17) cell infiltration with higher levels of regulatory cells (Tregs) infiltration in the Cd226−/− EAE mouse central nervous system (CNS) compared with that in the WT EAE mouse CNS. Moreover, the suppressive function of Cd226−/− Tregs was upregulated compared with that of WT Tregs. Furthermore, it was observed that the expression levels of CTLA-4 and TIGIT on Cd226−/− Tregs were higher than those on WT Tregs during EAE in the spleen and CNS. Our results demonstrate a pivotal role for CD226 in attenuating Treg function in EAE that was associated with downregulating the expression levels of CTLA-4 and TIGIT.  相似文献   
18.
Immunologic Research - The impairment of regulatory T cells (Tregs) is a characteristic feature of autoimmune hepatitis (AIH), and the degradation of tryptophan (Trp) to kynurenine (Kyn), by gamma...  相似文献   
19.
Some species of mycobacteria have been modified to transform sterols to valuable steroid synthons. The unique cell wall of mycobacteria has been recognized as an important organelle to absorb sterols. Some cell wall inhibitors (e.g., vancomycin and glycine) have been validated to enhance sterol conversion by interfering with transpeptidation in peptidoglycan biosynthesis. Therefore, two transpeptidase genes, pbpA and pbpB, were selected to rationally modify the cell wall to simulate the enhancement effect of vancomycin and glycine on sterol conversion in a 22‐hydroxy‐23,24‐bisnorchol‐4‐ene‐3‐one (4‐HBC) producing strain (WIII). Unexpectedly, the pbpA or pbpB gene augmentation was conducive to the utilization of sterols. The pbpB augmentation strain WIII‐pbpB was further investigated for its better performance. Compared to WIII, the morphology of WIII‐pbpB was markedly changed from oval to spindle, indicating alterations of the cell wall. Biochemical analysis indicated that the altered cell wall properties of WIII‐pbpB might contribute to the positive effect on sterol utilization. The productivity of 4‐HBC was enhanced by 28% in the WIII‐pbpB strain compared to that of WIII. These results demonstrated that the modification of peptidoglycan synthesis can improve the conversion of sterols to steroid synthons in mycobacteria.  相似文献   
20.
Parasitology Research - Trypanosoma lewisi (Kinetoplastea: Trypanosomatida: Trypanosomatidae) with a cosmopolitan distribution is the type species of the subgenus Herpetosoma, which includes ca. 50...  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