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   231132篇
  免费   21261篇
  国内免费   13160篇
耳鼻咽喉   2210篇
儿科学   2515篇
妇产科学   3450篇
基础医学   29450篇
口腔科学   4545篇
临床医学   27993篇
内科学   36127篇
皮肤病学   3084篇
神经病学   13069篇
特种医学   8025篇
外国民族医学   103篇
外科学   25538篇
综合类   33104篇
现状与发展   40篇
一般理论   27篇
预防医学   14988篇
眼科学   6063篇
药学   24081篇
  190篇
中国医学   11623篇
肿瘤学   19328篇
  2024年   742篇
  2023年   3150篇
  2022年   8065篇
  2021年   10277篇
  2020年   7653篇
  2019年   6858篇
  2018年   7621篇
  2017年   6841篇
  2016年   6460篇
  2015年   9584篇
  2014年   11736篇
  2013年   11213篇
  2012年   16202篇
  2011年   17295篇
  2010年   10984篇
  2009年   8694篇
  2008年   11735篇
  2007年   11315篇
  2006年   10818篇
  2005年   10267篇
  2004年   6951篇
  2003年   6414篇
  2002年   5481篇
  2001年   7945篇
  2000年   8044篇
  1999年   7525篇
  1998年   3541篇
  1997年   3268篇
  1996年   2362篇
  1995年   2212篇
  1994年   1943篇
  1993年   1303篇
  1992年   3118篇
  1991年   2718篇
  1990年   2346篇
  1989年   2241篇
  1988年   1972篇
  1987年   1740篇
  1986年   1453篇
  1985年   1244篇
  1984年   751篇
  1983年   603篇
  1982年   323篇
  1981年   290篇
  1980年   210篇
  1979年   386篇
  1978年   129篇
  1977年   112篇
  1974年   119篇
  1973年   124篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
Delta hepatitis virus infection in China   总被引:1,自引:0,他引:1  
To assess the prevalence, epidemiological features and prognostic implications of hepatitis D (Delta) in Sichuan Province, The People's Republic of China, 649 sera (515 from HBsAg positive patients and 134 from HBsAg negative subjects) were tested by radioimmunoassay (RIA) for antibody to the hepatitis D virus (anti-HD). Forty-seven sera (7.2%) showed some degree of reactivity. Serial dilutions of these sera indicated that prozoning was not responsible for the equivocal results. Thirty-four of the 47 sera were submitted under code to a second laboratory for independent analysis. According to those results anti-HD antibodies were detected in four of these sera. The overall prevalence of anti-HD in the HBsAg positive patients therefore was 0.8% (4/515). On the basis of clinical, biochemical and histological data 427 HBsAg positive sera were further divided into acute Type B hepatitis, chronic Type B hepatitis, healthy carrier state and hepatocellular carcinoma (HCC) subgroups. Two of 65 (3.1%) anti-HD positive sera belonged to the acute Type B hepatitis group; one of 104 (0.9%), the chronic Type B hepatitis group and one of 246 (0.4%), the healthy carrier group. No antibody was detected in sera from 12 HBsAg positive HCC patients. All HBsAg negative patients were negative for anti-HD antibody. The results of this study indicate that despite a high prevalence of hepatitis B virus infection, positive serology for delta virus is uncommon in Sichuan Province, The People's Republic of China.  相似文献   
83.
以钒基核苷酸复合物为核酸酶抑制剂,从人胚组织中制备总RNA,所得产品几乎不含DNA和蛋白质,经过分离Poly(A)~ mRNA,证明制品有合成cDNA的完整功能,方法比较简捷,适于大量制备以满足分离mRNA 之需,并讨论了此法的优缺点。  相似文献   
84.
85.
X Dong  M He  X Song  B Lu  Y Yang  S Zhang  N Zhao  L Zhou  Y Li  X Zhu  R Hu 《Diabetic medicine》2007,24(12):1482-1486
AIMS: Our aim was to assess performances of the Cockcroft-Gault and simplified Modification of Diet in Renal Disease (MDRD) formulae in estimating glomerular filtration rate (GFR) in Chinese diabetic populations and their association with vascular risks. METHODS: A total of 1009 patients with Type 2 diabetes were categorized into low estimated GFR groups (GFR < 60 ml/min/1.73 m(2)) and control groups by the two equations. The performances of these formulae were assessed at different stages of kidney function. Carotid artery intima-media thickness (IMT) and the prevalence of diabetic retinopathy or albuminuria were compared among the groups. The ability of these formulae to identify established vascular risk markers using sensitivity, specificity, positive and negative predictive values were also compared. RESULTS: The prevalence of low estimated GFR was 32.7% with the Cockcroft-Gault formula and 5.2% with the MDRD formula, respectively. In low estimated GFR subjects by the MDRD formula, IMT was significantly thicker than those by the Cockcroft-Gault formula (1.2 mm vs. 1.0 mm; P < 0.05), with a higher prevalence of albuminuria (78.4 vs. 52.8%, P < 0.05) and diabetic retinopathy (46.5 vs. 30.5%; P < 0.05). The Cockcroft-Gault formula gave a specificity of 71.7% and a sensitivity of 37.0%, and the MDRD formula gave a specificity of 96.6% and a sensitivity of 7.9% in estimating low GFR relevant for established vascular risks. CONCLUSIONS: These formulae performed differently in Chinese diabetic populations. The simplified MDRD formula is minimally superior to the Cockcroft-Gault formula for its high specificity and positive predictive values in estimating low GFR relevant for vascular risks.  相似文献   
86.
A study on the pathologic findings after recession and resection of extraocular muscles in rabbits was performed. Fibrosis of the extraocular muscles increased with time, which showed no difference between the recessed and resected muscles. Inflammation and foreign body reaction decreased with time, which showed no difference between the recessed and resected muscles. Adhesions of extraocular muscles to the sclera were observed from one month after the operation. The resected muscles showed milder adhesion to the sclera than the recessed ones. The operated extraocular muscles showed atrophies at one month, which showed no difference between the recessed and resected muscles. According to our results, when reoperation is needed, fibrosis of the extraocular muscles after recession and resection should be considered when making a decision on the amount of muscle to be recessed and resected.  相似文献   
87.
88.
以曼氏血吸虫的虫卵和成虫免疫家兔后所产生的特异性抗体,可用以日本血吸虫虫卵、尾蚴和成虫为抗原分别进行的COP,CHR和ELACIEP测出,表明两种人体血吸虫存有显著的交叉抗原成分。应用此种血清交叉反应性,以检测抗异种人体血吸虫的抗体,似有效而可取的,可用以辅助诊断援外回国人员是否感染国外人体血吸虫病。  相似文献   
89.
The authors reviewed the radiographic manifestations of 17 cases of parosteal osteosarcoma, with pathologic correlation in 15. There were two types of parosteal osteosarcoma radiologically. The majority of cases were type I with uniformly dense masses which had regular borders. They often adhered to the cortex and showed no evidence of soft-tissue invasion which correlated with low-grade pathologic malignancy and a relatively benign clinical course. Type II involved the bone, soft-tissue and the medullary cavity. These lesions were poorly differentiated and frequently accompanied by metastatic lesions.
  相似文献   
90.
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