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   1075290篇
  免费   71587篇
  国内免费   1366篇
耳鼻咽喉   15015篇
儿科学   34608篇
妇产科学   28627篇
基础医学   153417篇
口腔科学   29555篇
临床医学   94949篇
内科学   203727篇
皮肤病学   24396篇
神经病学   81452篇
特种医学   42966篇
外国民族医学   201篇
外科学   163230篇
综合类   21706篇
现状与发展   1篇
一般理论   263篇
预防医学   74600篇
眼科学   24536篇
药学   86125篇
  7篇
中国医学   2805篇
肿瘤学   66057篇
  2019年   7760篇
  2018年   11298篇
  2017年   8910篇
  2016年   10100篇
  2015年   11268篇
  2014年   15275篇
  2013年   22202篇
  2012年   30560篇
  2011年   32302篇
  2010年   18957篇
  2009年   17819篇
  2008年   29958篇
  2007年   32084篇
  2006年   32712篇
  2005年   31046篇
  2004年   29738篇
  2003年   28563篇
  2002年   27548篇
  2001年   60030篇
  2000年   61487篇
  1999年   50943篇
  1998年   12447篇
  1997年   11004篇
  1996年   11017篇
  1995年   10323篇
  1994年   9347篇
  1993年   8858篇
  1992年   37801篇
  1991年   36283篇
  1990年   35749篇
  1989年   34294篇
  1988年   30869篇
  1987年   30000篇
  1986年   28225篇
  1985年   26455篇
  1984年   19192篇
  1983年   16117篇
  1982年   8825篇
  1979年   17032篇
  1978年   11407篇
  1977年   10233篇
  1976年   8839篇
  1975年   10068篇
  1974年   11652篇
  1973年   11274篇
  1972年   10755篇
  1971年   10093篇
  1970年   9255篇
  1969年   8940篇
  1968年   7917篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Burkitt’s lymphoma is a high-grade, rapidly growing B-cell neoplasm. It is recognized by its aggressive course, brief median survival, and low rates of long-term survival. The authors discuss the case of a patient who acutely presented with intraabdominal complications from a new onset of Burkitt’s lymphoma. The clinical and pathological features, staging, treatment options, and survival data are reviewed. In addition, the role of surgical intervention is carefully analyzed.  相似文献   
152.
Glutathione-S-transferase (GST) genes encode a family of detoxification enzymes that offer protection against endogenous and exogenous sources of reactive oxygen species (ROS). Germline variations in GST genes may alter the catalytic efficiency of GST isoenzymes leading to a potential increase in susceptibility to the genotoxic effects of ROS and electrophilic substances. A nested case-control study design was used to examine the association between the polymorphic GST genes and prostate cancer risk among Finnish male smokers of the ATBC Cancer Prevention Study. A case-case analysis was used to determine the association between these genetic polymorphisms and prostate cancer progression. Germline DNA was obtained from 206 prostate cancer cases and 194 controls frequency matched on age, intervention group and study clinic. Cases and controls were genotyped for three GST genes using MALDI-TOF mass spectrometry or multiplex polymerase chain reaction (PCR). Relative to the wild-type genotype, we observed a 36% reduction in prostate cancer risk associated with the GST-M1-null genotype (odds ratio (OR) 0.64, 95% confidence interval (CI) 0.43, 0.95). Unlike GST-M1, GST-T1-null (OR 0.74, 95% CI 0.42, 1.33) and GST-P1*B (OR 1.10, 95% CI 0.72, 1.69) were not strongly associated with prostate cancer risk. We did not observe any significant associations between the selected polymorphic GST genes and tumour grade or stage. In conclusion, we did not observe a direct association between polymorphic GST-T1 or GST-P1 and prostate cancer risk. Our observation of a relatively strong inverse association between the GST-M1-null genotype and prostate cancer risk needs to be confirmed in larger association studies.  相似文献   
153.
Levels of the soluble form of the triggering receptor expressed on myeloid cells (sTREM)-1 are elevated in severe sepsis. However, it is not known whether sTREM-1 measurements can distinguish milder bacterial infections from noninfectious inflammation. The present authors studied whether serum sTREM-1 levels differ in community-acquired pneumonia, exacerbations of chronic obstructive pulmonary disease (COPD), asthma and controls, and whether sTREM-1 may be used as a surrogate marker for the need for antibiotics. Serum sTREM-1 levels in 150 patients with pneumonia, COPD and asthma exacerbations and 62 healthy controls were measured. Serum sTREM-1 levels were significantly elevated in pneumonia (median 295.2 ng x mL(-1)), COPD (280.3 ng x mL(-1)) and asthma exacerbations (184.0 ng x mL(-1)) compared with controls (83.1 ng x mL(-1)). Levels were higher in pneumonia and Anthonisen type 1 COPD exacerbations than in type 2 and 3 COPD and asthma exacerbations. The area under the receiver operating characteristics curve for sTREM-1 as a surrogate marker for the need for antibiotics was 0.77. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 were elevated predominantly in pneumonia and Anthonisen type 1 COPD exacerbations versus type 2 and 3 chronic obstructive pulmonary disease exacerbations, asthma and controls. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 has moderate but insufficient accuracy as a surrogate marker for the need for antibiotics in lower respiratory tract infections.  相似文献   
154.
Sugar and tooth decays are bound closely. The mechanisms of destruction of the tooth from the glycolyse are known. The role played by the food in the development of the caries is unique. Foods sweetened of all ways, rich in sucrose are responsible of the intervening of the carious lesions. The transformation of the fermentable sugars in lactic with the absence of hygiene and the action conjugated of the bacteria leads to tooth decays in temporary and permanent denture that evolve very quickly in the absence of treatment. Reasons for which the authors put in evidence in this survey, the influence of the food sweetened on the teeth at the children while showing the cases of caries and its complications due to the excessive consumption of fermentable hydrates of carbon.  相似文献   
155.
156.
157.
158.
We have recently shown that HPV-positive tonsillar carcinoma in young patients exhibits nonkeratinizing basaloid morphology and a characteristic immunophenotype. The purpose of this study was to review a large number of cases of oropharyngeal carcinomas, in all age groups, and to identify tumors with nonkeratinizing morphology. Using polymerase chain reaction (PCR) the prevalence and type of HPV DNA was determined in representative cases and in a control group of conventional keratinizing squamous cell carcinomas. The tumors were further characterized with a panel of immunohistochemical stains. A total of 235 carcinomas were reviewed; 141 of the tonsils and 94 in the base of tongue. Ninety (36%) of the tonsillar and 30 (32%) of the base of tongue carcinomas were nonkeratinizing (NKCa) with basal cell features; the rest were classical keratinizing squamous cell carcinomas (KSCC). HPV DNA, particularly type 16, was identified in 10 (100%) of 10 of NKCA and in only 2 (20%) of 10 of KSCC (P = .0014). NKCas were strongly reactive to p16 antibodies while KSCC showed weak and focal reactivity. Higher Ki67 and lower p53 staining scores were observed in NKCa as compared to KSCC. It is concluded that NKCa of the tonsils and base of tongue is a distinct subtype of squamous cell carcinoma of the head and neck with high prevalence of HPV DNA and a characteristic immunophenotype.  相似文献   
159.
160.
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