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   531208篇
  免费   27806篇
  国内免费   497篇
耳鼻咽喉   6685篇
儿科学   16984篇
妇产科学   12624篇
基础医学   92829篇
口腔科学   12357篇
临床医学   48600篇
内科学   95725篇
皮肤病学   11881篇
神经病学   34103篇
特种医学   19780篇
外国民族医学   53篇
外科学   78166篇
综合类   7640篇
现状与发展   2篇
一般理论   111篇
预防医学   38687篇
眼科学   11956篇
药学   41515篇
  1篇
中国医学   1128篇
肿瘤学   28684篇
  2019年   3907篇
  2018年   5757篇
  2017年   4140篇
  2016年   4880篇
  2015年   5380篇
  2014年   7131篇
  2013年   10527篇
  2012年   15627篇
  2011年   17443篇
  2010年   9980篇
  2009年   8842篇
  2008年   15758篇
  2007年   17493篇
  2006年   16994篇
  2005年   16314篇
  2004年   15911篇
  2003年   15301篇
  2002年   14812篇
  2001年   22456篇
  2000年   23005篇
  1999年   18960篇
  1998年   5238篇
  1997年   4374篇
  1996年   4415篇
  1995年   4139篇
  1992年   14448篇
  1991年   15850篇
  1990年   15968篇
  1989年   15667篇
  1988年   14334篇
  1987年   14225篇
  1986年   13189篇
  1985年   12717篇
  1984年   9423篇
  1983年   8025篇
  1982年   4205篇
  1979年   8958篇
  1978年   6397篇
  1977年   5173篇
  1976年   5519篇
  1975年   6628篇
  1974年   7431篇
  1973年   7176篇
  1972年   6613篇
  1971年   6321篇
  1970年   5898篇
  1969年   5484篇
  1968年   5170篇
  1967年   4633篇
  1966年   3970篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Summary Eight patients with malignant gliomas verified on CT scan, received an intravenous injection of 50 mg of Adriamycin R, 24 hours prior to surgical removal of the tumour. Peroperatively, both tumour and surrounding tissue specimens were obtained for determination of the tissue concentrations of Adriamycin and its reduced metabolite Adriamycinol. It was found that Adriamycin could be detected in tumour tissue from all patients. The concentration varied between 0,9 and 4,6 nmol/g tissue. In contrast, Adriamycin could only be detected in surrounding brain tissue from one patient.In anin vitro study a human malignant glioma cell line (U-251 MG) was exposed to various concentrations of Adriamycin for 24 hours. It was found that an intracellular drug concentration above 30 nmol/g cells caused a concentration dependent inhibition of cell growth. Thus, it is likely that the poor effect of Adriamycin on patients with malignant gliomas is due to an ineffective drug accumulation in the tumour tissue.  相似文献   
72.
73.
OBJECTIVE: To determine the most frequent clinical causes of a prolonged activated partial thromboplastin time (APTT) result, and to determine whether a new heparin-removal device (the Hepchek, Pall Biomedical, Glen Cove, NY 11542) is capable of efficiently detecting the causes of these values. DESIGN: A combination of chart review and laboratory testing comparing the criterion standard--the heparin chromogenic substrate assay--with the Hepchek. Laboratory investigations were blinded and controlled. SETTING: Inpatient, acute-care hospital. PATIENTS: A total of 1,000 hospital patients with a variety of hemostatic disorders. MAIN OUTCOME MEASURE: The extent to which the Hepchek accurately identified the etiology of a prolonged APTT result. RESULTS: The APTT was prolonged in 25.2% of samples. The presence of heparin in the sample was confirmed by chromogenic assay or by using the Hepchek heparin-removal filter. The presence of heparin was confirmed in 12.8% of all samples and in more than 50% of all abnormal samples. The cause of the abnormal APTT was often unappreciated by the clinician. Bayesian analysis of the Hepchek's ability to diagnose heparin correctly as the cause of the abnormal APTT showed a sensitivity of 100% and specificity of 99.9%. CONCLUSION: Use of the Hepchek in the routine clinical laboratory is an efficient and rapid method of detecting heparin as a cause of isolated prolonged APTT results, and should reduce demands for unwarranted coagulation analyses and inappropriate treatment with blood products.  相似文献   
74.
Using hierarchical cluster analysis, applied to 47 cases of Guillain-Barre Syndrome (GBS) incident in South-West Stockholm (SWS) during the period from January 1973 to June 1992, we identified three major clinicoepidemiological subgroups. The first subgroup, 25.5% of the cases (26.7 ± 6.7 years), recorded a peak incidence at ages 20–29 years and presented significant differences from other subgroups, a high proportion of cases with onset at low age preceded by respiratory infection (83.3%) and with normal motor conduction velocity (50.0%). Also found, were less affected biological parameters, a rapidly progressive course and independence in gait at one month after onset. A second subgroup, 27.7% of cases, was severely affected, clinically and functionally. It consisted predominantly of young individuals (22.7 ± 11.1 years), with a high incidence (69.2% of cases) in autumn. A third subgroup, comprising 40.47; of cases, was older (61.1 ± 11.0 years) and, in general, also severely affected. The incidence of this form appeared to be invariant with time.  相似文献   
75.
76.
In experiments on albino rats it was established that three administrations of indomethacin in a dose of 0.01 g/kg body weight induced a severe damage of the liver characterized by disturbances of hepatocytic membranes, bile-producing and protein-producing functions of the liver, an enhancement of lipid peroxidation, a decrease of reduced glutathione pool. Antioxidants (tocopherol acetate, essentiale, legalon, flacumin) limit manifestations of indomethacin, hepatotoxicity, as a result of which tha functional-biochemical disorders in the liver show up to a lesser degree. During the combined use of antioxidants in indomethacin-induced lesions of the liver their hepatoprotective activity increases.  相似文献   
77.
To determine the potential effect of screening on referral patterns, an adult population sample (4,404 men, 5,164 women, 20-69 years of age) was systematically recruited and screened for hypercholesterolemia and then analyzed by different cholesterol referral recommendations. Using levels suggested by the Lipid Research Clinics Coronary Primary Prevention Trial (greater than or equal to 265 mg/dL), 7.3% of men and 5.8% of women would be referred for follow-up. With the suggested recommendations of the National Cholesterol Education Program (NCEP), (greater than or equal to 200 mg/dL), 49.2% of men and 40.2% of women would be referred. The use of age-related definitions of the NIH Consensus Conference on Lipid Lowering results in 28.0% referrals in men and 21.8% in women. From this population, hypercholesterolemia subjects (greater than or equal to 265 mg/dL at screening; n = 624) were invited for a second cholesterol determination (58% returned), which found 36% below the 265 mg/dL level. Population screening for cholesterol is likely to produce large numbers of patients for follow-up, with the actual numbers strongly dependent on cutoff levels and age-sex distributions. Referral and follow-up of these patients may place a significant load on an unprepared health care community.  相似文献   
78.
79.
80.
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