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   521243篇
  免费   34728篇
  国内免费   622篇
耳鼻咽喉   6938篇
儿科学   17057篇
妇产科学   13671篇
基础医学   86058篇
口腔科学   14586篇
临床医学   45235篇
内科学   95186篇
皮肤病学   12242篇
神经病学   36797篇
特种医学   18723篇
外国民族医学   63篇
外科学   78531篇
综合类   8667篇
一般理论   144篇
预防医学   39781篇
眼科学   12204篇
药学   41080篇
中国医学   1054篇
肿瘤学   28576篇
  2018年   5120篇
  2016年   4220篇
  2015年   4656篇
  2014年   6291篇
  2013年   9875篇
  2012年   13375篇
  2011年   14757篇
  2010年   8562篇
  2009年   8013篇
  2008年   14156篇
  2007年   15112篇
  2006年   15319篇
  2005年   14775篇
  2004年   14416篇
  2003年   13704篇
  2002年   13570篇
  2001年   24273篇
  2000年   25289篇
  1999年   20744篇
  1998年   5509篇
  1997年   4780篇
  1996年   5131篇
  1995年   4691篇
  1994年   4396篇
  1992年   15840篇
  1991年   16452篇
  1990年   16518篇
  1989年   15895篇
  1988年   14687篇
  1987年   14553篇
  1986年   13714篇
  1985年   13074篇
  1984年   9693篇
  1983年   8306篇
  1982年   4600篇
  1981年   4267篇
  1979年   9483篇
  1978年   6900篇
  1977年   5826篇
  1976年   5639篇
  1975年   6436篇
  1974年   7681篇
  1973年   7160篇
  1972年   7002篇
  1971年   6714篇
  1970年   6195篇
  1969年   5911篇
  1968年   5580篇
  1967年   5027篇
  1966年   4466篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
J Bódis  I Csaba  E Gács 《Orvosi hetilap》1992,133(1):47-48
The authors described a 7 weeks old cervical pregnant case, whome was administered 250 mg methotrexate in infusion to eliminate the throphoblastic tissue. 3 days later the HCG was negative in the urine. After the dilatation of cervix by laminaria, the collapsed amniotic sac came from the cervix with minimal hemorrhage. They suggest the method is suitable to prevent the serious complications of cervical pregnancy.  相似文献   
992.
HIV-1 infectivity of human carcinoma cell lines lacking CD4 receptors.   总被引:2,自引:0,他引:2  
Human immunodeficiency virus type 1 (HIV-1) prototype, HIV1 LAV, and a Zairian virus HIV1 NDK, an isolate highly cytopathic for CD4+ lymphocytes, were used to infect eleven different CD4 negative non-lymphoid human cell lines. Eight of the lines were derived from carcinomas wherein human papillomavirus was thought to have been etiologic. All these cell lines lacked CD4 receptor and CD4 specific mRNA. After cocultivation with sensitive CEM cells, HIV-1 LAV was rescued from six infected cell lines and HIV-1 NDK from nine. Shedding of free virus into the culture medium was observed in three cell lines infected by HIV-1 NDK and in only one cell line infected by HIV-1 LAV. The infectibility of CD4 negative cell lines indicates that both HIV-1 strains were able to use a CD4 independent mechanism to infect the cells; however, HIV-1 NDK showed the higher efficiency of infection. This virus was also able to overcome the intracellular block of viral reproduction. These results suggest that a broader spectrum of cell types of non-lymphoid origin lacking the CD4 receptor can serve as a viral reservoir. In some cases they are direct producers of infectious HIV-1 particles. This suggests, that in addition to immunosuppressive mechanisms, HIV-1 could play a more direct role in induction of neoplastic changes.  相似文献   
993.
The relationship between dietary fat intake and fasting plasma lipid levels was assessed in 35 female and 19 male adolescents recruited from two local education authority schools in Norwich, UK. Dietary intakes were assessed using a 7-day weighed dietary record method, coupled with the collection of duplicate diets. Fat and energy intakes calculated using food composition tables were compared with values obtained by direct analysis of duplicate diets. Fasting plasma lipid levels (total, HDL and LDL cholesterol and triglycerides) were measured and compared with total dietary lipids and fatty acid intakes. The average proportion of energy consumed as fat was higher than is currently considered desirable but lower than previous studies have reported for adults. Mean serum total cholesterol values were 4.2 (SEM 0.1) mmol for females and 4.5 (SEM 0.2) mmol for males; this difference was not statistically significant. In male subjects the dietary fatty acid profiles were significantly correlated with several parameters of plasma lipid status which are thought to be risk factors for coronary heart disease, and in particular with the ratio of total:HDL cholesterol.  相似文献   
994.
Translated from Khimiko-farmatsevticheskii Zhurnal, Vol. 26, No. 5, pp. 43–45, May, 1992.  相似文献   
995.
Ten adult humans were vaccinated with the Japanese acellular pertussis vaccine JNIH-3, containing detoxified pertussis toxin (PT), formaldehyde, and filamentous hemagglutinin. The vaccination induced a specific antibody response to PT and filamentous hemagglutinin, and a Western blot (immunoblot) analysis of the antibody response to PT revealed antibodies to PT subunits S1, S2, S3, S4 and S5. The response of peripheral lymphocytes to PT was assessed in an in vitro proliferation assay. A proliferative response to detoxified PT and PT dimers S2-S4 and S3-S4 was found, and it was further demonstrated that the proliferative response to detoxified PT and dimer S2-S4 was mediated by T cells of the CD4+ phenotype. The specificity of the proliferative response to subunit S4 was analyzed with a range of synthetic peptides synthesized on the basis of the primary sequence of subunit S4. The proliferative response to the peptides revealed two major and one minor T-cell epitope located in the NH2-terminal end of subunit S4.  相似文献   
996.
Scientific-Research Center of Biomedical Radioelectronics, Moscow. Translated from Meditsinskaya Tekhnika, No. 6, pp. 36–37, November–December, 1992.  相似文献   
997.
998.
What is clusterin?   总被引:1,自引:1,他引:0       下载免费PDF全文
  相似文献   
999.
Ultrasonography was performed in 661 dialysis patients and acquired cystic disease of the kidney was found in 156 (125 men and 31 women). A higher incidence of cystic disease was found in males. There was no significant difference between the patients with and those without acquired cystic disease in terms of average age, but the duration of haemodialysis in those with acquired cystic disease was significantly longer. There was an increased incidence of cystic disease in patients with glomerulonephritis and the duration of haemodialysis in these patients was significantly longer. This suggests that the increased incidence of acquired cystic disease of the kidneys in the patients with glomerulonephritis is simply related to the longer duration of treatment. Twelve patients with renal carcinoma were found in this study. The average age at diagnosis of renal carcinoma was not significantly different between the patients with and those without acquired cystic disease, but the duration of dialysis was significantly longer in renal carcinoma patients with acquired cystic disease. The incidence of renal carcinoma in dialysis patients with acquired cystic disease was 3.85% and in those without it was 1.19%. These rates are considerably higher than those found in the general population and indicate that the risk of renal carcinoma is higher in dialysis patients both with and without acquired cystic disease.  相似文献   
1000.
Ten patients with osteosarcomas and rotation plasties made themselves available for a psychological survey. The time elapsed after their operations was between two and ten years, giving an average of six years. All patients were free of tumours at the time of the follow-up examination. Both in personal interviews and in psychological tests, it was possible to observe a very positive development of these patients' attitudes. Contributory factors in this context were discussions with the doctors administering treatment, the cheerful atmosphere of the hospital and the nursing staff, the physicotherapists and ergotherapists, and the excellent social support which all those interviewed also received from their relatives. Continuous positive motivation, a favourable social dialogue and patients' ability to control their own lives would appear to be the key factors in helping patients to come to terms with their illness.  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