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   106183篇
  免费   9634篇
  国内免费   6267篇
耳鼻咽喉   1231篇
儿科学   1329篇
妇产科学   1003篇
基础医学   11495篇
口腔科学   1646篇
临床医学   11807篇
内科学   13685篇
皮肤病学   1654篇
神经病学   4551篇
特种医学   4994篇
外国民族医学   21篇
外科学   10171篇
综合类   19927篇
现状与发展   30篇
一般理论   7篇
预防医学   8593篇
眼科学   2650篇
药学   12043篇
  114篇
中国医学   7095篇
肿瘤学   8038篇
  2024年   354篇
  2023年   1397篇
  2022年   3357篇
  2021年   4624篇
  2020年   3466篇
  2019年   2820篇
  2018年   2984篇
  2017年   3084篇
  2016年   3041篇
  2015年   4775篇
  2014年   6033篇
  2013年   6378篇
  2012年   9145篇
  2011年   9735篇
  2010年   7115篇
  2009年   6188篇
  2008年   7253篇
  2007年   6785篇
  2006年   6265篇
  2005年   5322篇
  2004年   3919篇
  2003年   3753篇
  2002年   3055篇
  2001年   2233篇
  2000年   1821篇
  1999年   1408篇
  1998年   817篇
  1997年   730篇
  1996年   625篇
  1995年   560篇
  1994年   537篇
  1993年   355篇
  1992年   378篇
  1991年   349篇
  1990年   290篇
  1989年   263篇
  1988年   173篇
  1987年   190篇
  1986年   143篇
  1985年   103篇
  1984年   56篇
  1983年   42篇
  1982年   40篇
  1981年   27篇
  1980年   27篇
  1979年   16篇
  1978年   6篇
  1975年   7篇
  1973年   10篇
  1972年   6篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
101.
冠脉内支架临床发展策略   总被引:1,自引:0,他引:1  
冠脉内支架是临床上预防PTCA并发症的有效措施,但金属支架固有的血栓菜成原性和对血管壁组织的永久性刺激可导致院内心脏事件和再狭窄。为解决上述问题,作者提出,血管内支架联合靶向药物传输离子照射或基因治疗、基因修饰的内皮细胞的种植支架、吱物可吸收缓释药物支架材料研制为临床冠脉内支架开辟了广阔的发展前景。  相似文献   
102.
103.
We develop an integrated model of isolated rat arterial resistance vessel (RV), which can simulate its major property of myogenic response. The vascular smooth muscle cell is an important component of the wall of this vessel, and serves as a vasomotor organ providing the active tension generation that underlies the myogenic response of the wall to stretch. In the previous study, we focused on the development of a smooth muscle cell model that can mimic the strain-sensing and force-generating features of the myogenic mechanism. In the current model, we embed this cell model in a larger vessel wall configuration, and couple the time course of cellular contractile activation to macroscopic changes in vessel diameter. The integrated model is used to mimic published pressure-vessel diameter data obtained from isolated RVs that are mounted in a hydraulic test apparatus. The model provides biophysically based insights into the myogenic mechanism as it responds to changes in transmural pressure, in the presence and absence of Ca2+ blockers applied to the bathing fluid.It mimics measured data very well and provides a model that is able to link events at subcellular level to macroscopic changes in vessel diameter. The model initiates a mechanistic approach to investigate myogenic response, which has not been taken previously by any other models.  相似文献   
104.
105.
In this study we investigate the expression pattern of mucin genes in the human testis and evaluate the relationship between the expression of mucin genes and impaired spermatogenesis in the human testis. Thirty human testis tissues were collected from patients undergoing diagnostic testicular biopsy to investigate the cause of infertility. One part of the tissue underwent histological observation, and the other part of the tissue was subjected to semiquantitative RT-PCR of mucin genes, that is, mucin1, 2, 3, 4, and 9. The relative amount of mucin mRNAs was calculated by densitometry using glyceraldehydes-3-phosphate dehydrogenase (GAPDH) as an internal control. The samples were histologically diagnosed as either obstructive azoospermia with normal spermatogenesis (n = 13) or non-obstructive azoospermia with impaired spermatogenesis (n = 17). In the human testis with normal spermatogenesis, mRNA expression of mucin1, 9, 13 and GAPDH were found, but RT-PCR products of mucin 2, 3 and 4 were not detected. In the testis with impaired spermatogenesis, however, RT-PCR product of mucin1 was not found. There was no difference in the other mucin mRNA expression patterns between the testis with either normal or impaired spermatogenesis. To our knowledge, this study is the first that has detected the mRNA of mucin9 and 13 in human testis. This study also shows that mucin1 expression might be closely related to spermatogenesis. Our findings should be substantiated by more direct evidence, such as mucin protein expression and localization.  相似文献   
106.
在解剖一成年男性尸体时发现肝外胆道系统(除胆囊外)异常扩张。报道如下:肝脏外形形态正常,肝外胆道各管径变粗,与周围组织无粘连,肝左管、肝右管、肝总管、胆囊管、胆总管的管径异常扩张(表1,图1)。  相似文献   
107.
108.
作者曾报道豚鼠肠粘膜下神经丛内,可能有一种特殊类型的淋巴管旁神经元。为了对上述的研究提供进一步的证据,本文应用显示神经元特异性烯醇化酶(NSE)的免疫组织化学方法,对这种类型的神经元进行了观察。胃肠神经丛内所有的神经元都呈NSE阳性反应,小肠和结肠粘膜下丛内的淋巴管旁神经元,也显同样的阳性反应。平滑肌和结缔组织细胞均为阴性。大多数淋巴管旁神经元具有典型的神经元形态特征;有些细胞虽不具有明显的神经元形态特点,但它们都显相同的NSE阳性反应。本文为我们前文报道的淋巴管旁神经元提供了更可信的证据。  相似文献   
109.
Jin H  Kang Y  Xiao C  Zhu K  Ma Y  Xie Q  Ma J  Xie Q  He C  Yang Z  Sun Z  Zhang X  Chen M  Zhang F  Wang B 《Viral immunology》2005,18(3):539-548
Prime-boost strategy has been exhibited its potency to enhance immune responses, which would be important to the success to develop a vaccine against the foot-and-mouth disease virus (FMDV). An eukaryotic expression construct encoding the FMDV capsid VP1 protein with a recombinant VP1 protein or a commercial FMDV vaccine were tested in the prime-boost strategy in mice and cattle trials. The levels of induced specific antibodies, T cell proliferations, and DTH activities were significantly higher in the prime-boost groups than in those vaccinated with DNA, protein or FMDV vaccine alone. More importantly, the levels of neutralizing antibodies in the former groups were significantly higher than others and could last for at least four months in cattle trials. This study suggests that the prime-boost strategy significantly improves the effective immunity and may provide a longer protection against FMDV infection.  相似文献   
110.
Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is important for downregulation of T-cell activation, and CTLA-4 gene polymorphisms have been implicated as risk factors for rheumatoid arthritis (RA). Previous studies of the association between the +49 polymorphism of the CTLA-4 gene in RA have provided conflicting results. In order to determine association of the CTLA-4 gene with RA in Chinese Han population, we used denaturing gradient gel electrophoresis (DGGE) to genotype polymorphisms of four SNPs (MH30, +49, CT60 and JO31) of the CTLA-4 gene in 326 RA patients and 250 healthy controls. Furthermore, meta-analysis of all available studies relating +49 polymorphism to the risk of RA was performed to confirm the disease association. Among the SNPs examined, the genotype frequencies of CTLA-4 +49 and CT60 in RA patients differed significantly from controls (P=0.028 and 0.007). In addition, the distribution of four haplotypes constructed by these two SNPs was significantly different between patients and controls (chi(2)=10.58, d.f. =3, P=0.014). The meta-analysis also revealed that in both European and Asian populations, the CLTA-4 +49 G allele was associated with the risk of RA. These results suggested that the CTLA-4 gene might be involved in the susceptibility to RA in the Chinese Han population and both +49 and CT60 of CTLA-4 gene might be the causal variants in RA disease.  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