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   3137543篇
  免费   222533篇
  国内免费   8400篇
耳鼻咽喉   42996篇
儿科学   99858篇
妇产科学   85656篇
基础医学   441133篇
口腔科学   88197篇
临床医学   284841篇
内科学   616072篇
皮肤病学   73624篇
神经病学   255849篇
特种医学   120903篇
外国民族医学   800篇
外科学   475519篇
综合类   63017篇
现状与发展   5篇
一般理论   1146篇
预防医学   235603篇
眼科学   71020篇
药学   231560篇
  10篇
中国医学   6544篇
肿瘤学   174123篇
  2019年   24022篇
  2018年   34206篇
  2017年   26340篇
  2016年   30466篇
  2015年   34311篇
  2014年   47130篇
  2013年   70490篇
  2012年   93674篇
  2011年   99002篇
  2010年   59586篇
  2009年   57223篇
  2008年   93213篇
  2007年   98818篇
  2006年   100722篇
  2005年   96635篇
  2004年   93125篇
  2003年   89700篇
  2002年   86951篇
  2001年   155604篇
  2000年   159594篇
  1999年   134652篇
  1998年   37541篇
  1997年   33156篇
  1996年   33397篇
  1995年   32272篇
  1994年   29623篇
  1993年   27729篇
  1992年   104460篇
  1991年   100356篇
  1990年   97348篇
  1989年   94040篇
  1988年   86123篇
  1987年   84415篇
  1986年   79117篇
  1985年   75554篇
  1984年   55902篇
  1983年   47348篇
  1982年   27356篇
  1981年   24335篇
  1979年   49465篇
  1978年   34445篇
  1977年   29463篇
  1976年   26946篇
  1975年   28853篇
  1974年   34291篇
  1973年   32479篇
  1972年   30490篇
  1971年   28404篇
  1970年   26460篇
  1969年   25327篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Effects of human recombinant TNF on the tumor blood vessels and on the thrombus formation were investigated in relation to its mode of antitumor action against Meth-A sarcoma transplanted in BALB/c mice. The extent of the blood vessel lesion was evaluated by using transparent chamber placed in the mouse skin. Bleeding, hyperemia and congestion were observed at 1-2h, 4-6h and 24h after TNF (1 X 10(4)U/mouse) administration, respectively. In contrast, no histological changes in the normal blood vessels were observed microscopically following TNF injection. Thrombus formation was evoked in the tumor vessels 4h after TNF injection. However, when thrombus formation was prevented by heparin, no difference was observed among antitumor action of TNF against Meth-A fibrosarcoma necrotic response and the rate of complete cure. These results suggest that the direct effects of TNF causing lesions in the tumor blood vessels plays an important role in its antitumor action.  相似文献   
992.
Clinical and biological data were evaluated using Desu univariate analyses or Cox multivariate analyses in a series of 1,777 chronic lymphocytic leukemia (CLL) patients from an Italian Cooperative Group. In univariate analyses, age and sex of patients, presence of bone marrow (BM; greater than or equal to 50%), and peripheral blood (PB; greater than or equal to 60,000/microL) lymphocytosis, anemia (hemoglobin [Hb] less than 11 g/dL), thrombocytopenia (less than 100,000/microL), direct Coombs' test positivity, hepatomegaly, splenomegaly, and extent of lymph node involvement were shown to be of significant prognostic value. Multivariate analyses, through a stepwise procedure, showed that the most important prognostic variables are Hb, hepatomegaly, lymph node involvement, PB lymphocytosis, and age and sex of patients. Further covariates would produce an improvement having a nonsignificant P value. Based on the results of multivariate analyses, a four-step staging using the significant variables of the Cox model is proposed.  相似文献   
993.
The records of 29 consecutive patients treated by a pure, open, anterior acromioplasty were reviewed retrospectively. Excluded from consideration were patients with the following pathologic diagnoses or histories: (1) previously attempted acromioplasty on the same shoulder; (2) intraoperatively confirmed rotator cuff tear; (3) any surgically treatable biceps tendon or acromioclavicular abnormality; (4) lost to follow-up study. Three different techniques were employed to perform the acromioplasties. The first technique required partial deltoid origin detachment with an osteotome. The second technique spared the deltoid origin, while again using an osteotome to perform the acromioplasty. The third technique also spared the deltoid origin but used a high-speed burr to perform the acromioplasty. Evaluated in terms of patient satisfaction, residual pain, length of convalescence, suboptimal results, and complications, the first technique proved to be the least effective. The second technique produced early, excellent results. The third technique, in which a burr was employed through an intact deltoid origin, was most effective; technically, the method was also relatively simple and reliable.  相似文献   
994.
995.
996.
A case of Goldenhar’s Syndrome in a 10 year old girl is reported. The unusual features are the absence of epibulbar dermoid which is one of the major hallmarks of the Syndrome and the presence of an associated Cyanotic Heart disease.  相似文献   
997.
The present paper deals with a Finnish long-term prospective study, the objective of which is to shed light on adjustment to retirement and old age. In this phase, only the preliminary findings of the initial survey carried out in 1982 are available. For the purposes of the study, a random sample of 200 individuals was drawn from among Turku inhabitants born in 1920. Another sample, consisting of 189 persons of the same age, was drawn from rural municipalities in the neighborhood of Turku. An extensive structured psychosocial interview could be conducted with a total of 339 subjects. The research methods used included e.g. the 36-item version of Goldberg's General Health Questionnaire (GHQ). Relatively little mental disturbance was revealed in the interview, and no major differences occurred between the urban and the rural sample. Somewhat over one-third of both samples were probable psychiatric cases as defined according to the GHQ.  相似文献   
998.
Surgically-obtained tissue specimens from 41 patients with ventricular aneurysm were studied electron microscopically. The tissue from the resected aneurysms showed substantially varied morphological differences. In some, there were extensive regions of scar containing increased fibrotic material and few cells, in others there were also larger contiguous regions of myocardium with an essentially normal appearance. In the preserved myocardial regions, the cardiac cells showed moderate hypertrophy. There was an increase in contractile substance in parallel with an increase in mitochondria and enlargement of the nucleus with frequent waves and invaginations in the cell membrane. The cells at the marginal regions between fibrous tissue and preserved myocardium were frequently isolated from adjacent cells. In particular, when the isolated cells were completely surrounded by fibrous tissue, clear degeneration was apparent. These cells showed mainly a fibrillolysis with dissolution of the cross-bands and loss of the entire contractile apparatus. In compensation, occasionally there was proliferation of other cell structures, especially the free sarcoplasmatic reticulum. The hypertrophy of the still intact myocardial cells is considered compensatory for the infarct-incurred loss of tissue. The degenerative appearance is mainly attributable to fibrous tissue invasion. The diminished oxygen supply, compromised or abolished impulse conduction, loss of function and passive stretch during systole may be regarded as causes of the degeneration.  相似文献   
999.
1000.
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