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   212716篇
  免费   20040篇
  国内免费   13412篇
耳鼻咽喉   1929篇
儿科学   2409篇
妇产科学   2607篇
基础医学   23628篇
口腔科学   3708篇
临床医学   27926篇
内科学   28992篇
皮肤病学   2544篇
神经病学   9943篇
特种医学   7345篇
外国民族医学   97篇
外科学   21766篇
综合类   37699篇
现状与发展   47篇
一般理论   22篇
预防医学   16326篇
眼科学   5209篇
药学   23392篇
  223篇
中国医学   13922篇
肿瘤学   16434篇
  2024年   881篇
  2023年   3308篇
  2022年   8717篇
  2021年   10867篇
  2020年   8437篇
  2019年   6862篇
  2018年   7150篇
  2017年   6840篇
  2016年   6307篇
  2015年   9848篇
  2014年   12135篇
  2013年   11729篇
  2012年   17073篇
  2011年   18277篇
  2010年   12580篇
  2009年   10059篇
  2008年   12579篇
  2007年   11900篇
  2006年   11236篇
  2005年   10579篇
  2004年   6859篇
  2003年   6120篇
  2002年   4977篇
  2001年   4280篇
  2000年   4315篇
  1999年   3993篇
  1998年   2314篇
  1997年   2364篇
  1996年   1809篇
  1995年   1750篇
  1994年   1542篇
  1993年   918篇
  1992年   1291篇
  1991年   1126篇
  1990年   901篇
  1989年   844篇
  1988年   767篇
  1987年   626篇
  1986年   463篇
  1985年   397篇
  1984年   192篇
  1983年   167篇
  1982年   97篇
  1981年   123篇
  1980年   79篇
  1979年   108篇
  1978年   52篇
  1977年   51篇
  1976年   45篇
  1974年   44篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
神经肽Y(NPY)是广泛分布于中枢神经系统和外周神经各部位的神经肽类物质。本实验观察NPY在体外对几种免疫细胞活性的直接作用。结果表明,NPY对小鼠T淋巴细胞丝裂原反应性和NK细胞的杀伤活性均无明显影响(P>0.05),对巨噬细胞分泌溶菌酶有明显抑制作用(P<0.05);而对B淋巴细胞丝裂原反应性则有明显的促进作用(P<0.05)。上述结果提示,NPY对部分免疫细胞功能的影响因细胞种类而异。  相似文献   
42.
43.
在蟾蜍离体坐骨神经-缝匠肌制备的肌细胞终板进行细胞内记录,研究了雌酮对神经-肌接头传递的影响。结果表明:雌酮加于浸浴液能增加10μg筒箭毒处理组和10mmol/L MgCl2处理组制备的终板电位振幅,但前者的增加更显著;雌酮加入浸浴液30分钟后引起小终板电位的振幅和频率明显增加,但波形不改变,静息膜电位也不改变。这些结果提示,雌酮能增加神经-肌接头传递,且主要通过突触前机理的作用。  相似文献   
44.
As a part of our ongoing study on Alzheimer's disease (AD) in elderly African Americans, we obtained clinical assessment and apolipoprotein E (ApoE) genotype data on 288 individuals (including 60 with AD). The ApoE σ4 allele frequency was significantly increased in AD patients compared with controls. The age-adjusted odds ratio (OR) for AD in σ4 homozygotes was 4.83 (95% confidence interval [CI], 1.71–13.64) compared with the σ3/σ3 genotype, but the OR for AD with the σ3/σ4 genotype did not reach significance (1.20; 95% CI, 0.58–2.45). These findings suggest that the association between ApoE σ4 and AD is weaker in African Americans than in whites.  相似文献   
45.
Lyme disease presenting as urinary retention   总被引:1,自引:0,他引:1  
We report a case of Lyme disease that presented with urinary retention. The individual then experienced lower extremity paralysis. Paralysis and urinary retention resolved with intravenous ceftriaxone antibiotic. To our knowledge this is the first report of a urological manifestation as the initial clinical presentation of Lyme disease. Recognition of clinical symptoms and urological complications of Lyme disease also are discussed.  相似文献   
46.
47.
Canine cyclic hematopoiesis (CH) was first described in Gray Collies as the lethal gray syndrome, and was subsequently shown to be a counterpart of human cyclic neutropenia (CN). The disease is characterized by a recurrent cyclic change in the levels of neutrophils and other blood elements at approximately 12-day intervals. It is caused by an autosomally recessive gene with pleiotropic effects or a CH gene which is closely linked to a gray color gene. The infectious insult on affected animals is periodic but its clinical and pathologic effects are continual and cumulative Affected dogs die after weaning and rarely survive over 6 months of age. There is evidence of immunoregulatory defects in these dogs. Reciprocal bone marrow transplantation indicates that the defect resides in the bone marrow, but the actual site and mechanism of the defect has not been established. The disease in Gray Collies represents a unique model system for studying the mechanism of cyclic hematopoiesis and hematopoietic regulation. Studies of the disease have made conceptual contributions toward understanding and treatment of human cyclic neutropenia.  相似文献   
48.
BACKGROUND AND PURPOSE: Health-related quality of life (HRQOL) is primarily an assessment of how domains of life are affected by health. This study investigated the factors influencing HRQOL of Taiwanese patients with bronchial asthma. METHODS: A cross-sectional study was conducted to assess the factors influencing HRQOL. The sample consisted of 242 outpatients with bronchial asthma. The Chinese language version of the St. George's Respiratory Questionnaire was used to measure HRQOL. Data were analyzed using simple regression and multiple regression. RESULTS: Age, marital status, level of education, asthma severity, peak expiratory flow, and previous hospital admissions were found to be predictors of HRQOL. Gender, duration of disease, and history of emergency visits were not correlated with HRQOL. The variables entered in the HRQOL model accounted for 17.4% of the total variance (adjusted R(2)). The regression coefficients indicated that the mean scores increased 7.68 in patients with moderate to severe disease severity, and increased 7.34 in patients with a history of hospital admissions. The mean scores decreased 7.60 in married patients. CONCLUSION: This study found that marital status, asthma severity, and history of hospital admissions were major predictors of HRQOL in Taiwanese patients with bronchial asthma.  相似文献   
49.
Bulletin of Environmental Contamination and Toxicology -  相似文献   
50.
The measurement of amniotic fluid (AF) acetylcholinesterase isoenzyme (AChEI) is a relatively new method for early diagnosis of open neural tube defects (NTDs). As quantitative methods are of unproven reliability at present, the authors used a high resolving power qualitative method-vertical slab polyaerylamide gel electrophoresis. The benefits of this technique are: simplicity of operation, accuracy, unsophisticated equipment, and easily available reagents. Combined results of 9 NTDs studies revealed that samples from early pregnancy gave more accurate results than those from late pregnancy.  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