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   6995篇
  免费   352篇
  国内免费   31篇
耳鼻咽喉   138篇
儿科学   129篇
妇产科学   76篇
基础医学   965篇
口腔科学   179篇
临床医学   469篇
内科学   1864篇
皮肤病学   60篇
神经病学   473篇
特种医学   278篇
外科学   994篇
综合类   29篇
预防医学   191篇
眼科学   255篇
药学   629篇
中国医学   9篇
肿瘤学   640篇
  2023年   38篇
  2022年   50篇
  2021年   108篇
  2020年   68篇
  2019年   89篇
  2018年   96篇
  2017年   60篇
  2016年   126篇
  2015年   115篇
  2014年   141篇
  2013年   168篇
  2012年   250篇
  2011年   276篇
  2010年   186篇
  2009年   139篇
  2008年   292篇
  2007年   282篇
  2006年   283篇
  2005年   320篇
  2004年   315篇
  2003年   308篇
  2002年   299篇
  2001年   308篇
  2000年   303篇
  1999年   255篇
  1998年   91篇
  1997年   69篇
  1996年   69篇
  1995年   55篇
  1994年   51篇
  1993年   40篇
  1992年   200篇
  1991年   161篇
  1990年   169篇
  1989年   163篇
  1988年   158篇
  1987年   148篇
  1986年   128篇
  1985年   109篇
  1984年   95篇
  1983年   69篇
  1982年   42篇
  1981年   39篇
  1979年   75篇
  1978年   54篇
  1976年   44篇
  1972年   44篇
  1971年   41篇
  1970年   42篇
  1968年   45篇
排序方式: 共有7378条查询结果,搜索用时 46 毫秒
991.
N Mori  K Oka  T Hanada  A Iizuka  M Kojima 《Cancer》1988,61(11):2231-2238
Leukemic cells from 25 cases of non-T-acute lymphocytic leukemia (ALL) in children were investigated for intracellular immunoglobulin by the use of immunoelectron microscopic study (immuno-EM). As a result, 12 cases were negative for both heavy and light chains of the immunoglobulin in the neoplastic cells. Of these, one case that was also negative for common ALL antigen (CALLA) was defined as null cell type. The remaining 11 cases were defined as common ALL type. Six cases were defined as pre-B-cell type because they were positive for cytoplasmic mu chain but negative for cytoplasmic light chains. Seven cases were defined as B-cell type, all of which possessed lambda light chains in the neoplastic cells. Immunohistologic studies using monoclonal antibodies showed that most non-T-ALL cases were positive for CALLA and B4, whereas about 50% of them were positive for B1. Our immuno-EM study suggests that it is one of the effective ways of subclassifying non-T-ALL in children.  相似文献   
992.
993.
994.
The rate of presence of surface immunoglobulins (sIg) and incidence of the surface receptors (SRBC-receptor, Fc-receptor and C3 receptor) were examined on the constituent cells of secondary nodules enucleated from human tonsils and foated in suspension. As most of the rosette-forming cells for SRBG-receptor were judged to belong to small round cells, the germinal center was considered to be a "non-T-cell region." The coronal B-lymphocytes and small germinal center cells were fairly matured B-cells because both bore sIg (100%), Fc receptor (25%) and C3 receptor (90-80%), while the former cells were thought to be more matured on the basis of their possession of surface δ-chain. As the large germinal center cells bore sig (50%) and carried Fc receptor (25%) and C3 receptor (50%), they seemed to be the major immature cells among the cell constituents of the secondary nodules. Moreover, it is presumed that the majority of the large germinal center cells are able to differentiate into coronal B-lymphocytes, probably memory cells, and a minor population of them into cIg-containing cells.  相似文献   
995.
Multiple aneurysms of the gastroepiploic artery and the ileocecal branch of the superior mesenteric artery were found in a 68-year-old male patient by angiography. The patient presented with one-hour postprandial epigastric pain of 10 years duration. Abdominal bruit was auscultated at the two different sites, one of which shifted downwards upon upright position. From the freely movable nature of the great omentum, this bruit, migrating upon postural change, was most likely from the gastroepiploic artery aneurysms. The aneurysms were excised and the abdominal bruit disappeared. The etiology of the aneurysms was suggested to be arterial fibrodysplasia histologically. From this experience, it was stressed that postural change should be added to a routine physical examination to rule out an aneurysm from the freely movable great omentum.  相似文献   
996.
We report a case of superficial esophageal carcinoma in a patient with esophageal varices. Esophagogram revealed a 2 cm large irregular mucosal elevation during work-up for esophageal varices which was acertained on endoscopical examination to be carcinoma. Biopsy material showed moderately differentiated squamous cell carcinoma. Subtotal esophagectomy was performed followed by reconstruction by cervical esophagogastrostomy through the retrosternal route. Few resected cases of esophageal carcinomas accompanied by esophageal varices have been reported because 1) early radiographic abnormalities of small superficial esophageal carcinomas can be overlooked in the case of large varices and 2) the number of operable cases is limited because of associated liver cirrhosis.  相似文献   
997.
Since the introduction of the CT scan in 1976, we have experienced 6 cases of the isolated fourth ventricle among 244 hydrocephalic patients (2.5%). Age at diagnosis of the isolated fourth ventricle ranged from 1 year 8 months to 13 years (mean age, 8 years, 6 months). The time interval between the first shunting procedure and the diagnosis of the isolated fourth ventricle varied from 1 year 5 months to 7 years 4 months (mean interval, 4 years 1 months). The prior hydrocephalus were due to intraventricular hemorrhage in two patients, meningomyelocele in a patient and brain tumor in three patients. Two patients had history of cerebrospinal fluid (CSF) infection and five cases underwent multiple shunt revisions. Posterior fossa signs were evident in all cases. It was quite easy to make a diagnosis of the isolated fourth ventricle with CT scan, which demonstrated a large rounded or pear-shaped midline cyst in the posterior fossa. Slit-like lateral ventricles were noted in three cases, while the remaining three had enlarged lateral ventricles. Ventriculography confirmed the isolation of the fourth ventricle in 5 cases. Metrizamide which had been injected into the fourth ventricle was diluted when CT scan was performed 48 hours later, and contrast medium disappeared since then. Magnetic resonance imaging (MRI) well showed the characteristic findings of the isolated fourth ventricle: cystic dilatation of the fourth ventricle, compression and distortion of the brain stem, upward tentorial herniation, occlusion of the aqueduct, downward displacement of the occipital lobe, septum formation of the fourth ventricle and accompanied anomalies such as, Chiari malformation or syringomyelia.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
998.
Bioavailabilities of morphine after rectal administration of three different morphine.HCl suppositories were evaluated in dogs, whose rectum was lavaged or non-lavaged. The suppositories were prepared with three fatty bases (Witepsol H-15, Witepsol W-35, Suppocire AT) by the fusion method. The release of morphine from the suppositories was examined after stored for two weeks at 30 degrees C. The plasma concentrations of morphine and its metabolites, morphine-3-glucuronide and morphine-6-glucuronide, were determined by high-performance liquid chromatography. The bioavailabilities of morphine after rectal administration were compared with those after intravenous and oral administration of morphine++.HCl solution. In the case of rectal lavaged dogs, the plasma levels of morphine after rectal administration of morphine.HCl solution were higher than those after oral administration of morphine.HCl solution. The release of morphine from Witepsol H-15 suppository was more rapid than those from other suppositories. Morphine after rectal administration of Witepsol H-15 suppository was rapidly absorbed in the rectum, and the inter-animal variation of its plasma levels was smaller than those of other suppositories. In rectal non-lavaged dogs, the bioavailabilities of morphine after rectal administration of morphine.HCl solution and suppositories decreased more than those of rectal lavaged dogs. Although the bioavailability of morphine after rectal administration of morphine.HCl was decreased by the influence of contents in the rectum, morphine from Witepsol H-15 suppository was more rapidly absorbed in the rectum, and the inter-animal variation of its plasma levels was smaller. These results indicate that, among their suppositories, Witepsol H-15 suppository is available for the terminal care of malignant disease.  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