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   1510篇
  免费   89篇
  国内免费   10篇
耳鼻咽喉   12篇
儿科学   83篇
妇产科学   25篇
基础医学   143篇
口腔科学   47篇
临床医学   155篇
内科学   325篇
皮肤病学   36篇
神经病学   56篇
特种医学   253篇
外科学   117篇
综合类   62篇
预防医学   107篇
眼科学   25篇
药学   103篇
中国医学   9篇
肿瘤学   51篇
  2021年   14篇
  2020年   7篇
  2019年   24篇
  2018年   21篇
  2017年   19篇
  2016年   12篇
  2015年   26篇
  2014年   48篇
  2013年   79篇
  2012年   50篇
  2011年   62篇
  2010年   48篇
  2009年   68篇
  2008年   40篇
  2007年   67篇
  2006年   49篇
  2005年   35篇
  2004年   31篇
  2003年   30篇
  2002年   32篇
  2001年   19篇
  2000年   28篇
  1999年   27篇
  1998年   80篇
  1997年   54篇
  1996年   64篇
  1995年   49篇
  1994年   51篇
  1993年   46篇
  1992年   18篇
  1991年   14篇
  1990年   16篇
  1989年   52篇
  1988年   36篇
  1987年   34篇
  1986年   24篇
  1985年   20篇
  1984年   22篇
  1983年   20篇
  1982年   20篇
  1981年   20篇
  1980年   13篇
  1979年   15篇
  1978年   12篇
  1977年   19篇
  1976年   13篇
  1975年   12篇
  1974年   6篇
  1973年   10篇
  1972年   10篇
排序方式: 共有1609条查询结果,搜索用时 15 毫秒
111.
Mammary tissue from nine Holstein cows was collected within 1 week of parturition and at 60 and at 180 days post partum. Blood samples were collected by puncture of the coccygeal vein or artery at 6-h intervals from 2 days before to 2 days after surgery. A membrane-enriched fraction of tissue homogenates was prepared by differential centrifugation. A microcomputer program (LIGAND) provided estimates of the dissociation constant (Kd) and receptor concentrations using Scatchard analysis of competition of radioiodinated human GH by bovine prolactin (NIH-bPRL-6), ovine prolactin (NIH-oPRL-15) and unlabelled human GH (NIH-hGH-I-1). Split-plot analysis of variance of hormone data indicated that mean prolactin concentrations during the periparturient period were greater than those at 60 or 180 days post partum. However, no differences were evident in prolactin content of blood samples collected immediately before biopsy. Analysis of variance of Scatchard data indicated that the Kd of the lactogenic hormone receptor did not differ at different stages of lactation, and averaged 89.7 nmol/l. Receptor concentrations were lower during the prepartum period than at 60 and 180 days post partum (0.65 vs 1.2 and 1.5 fmol/mg membrane protein respectively). The Kd of the lactogenic hormone receptor was similar when estimated with NIH-bPRL-6 or NIH-oPRL-15 competition, but 100-fold greater when estimated with NIH-hGH-I-1. It is concluded that lactogenic hormone receptor concentrations in bovine mammary tissue increase with the onset of lactation, with a pattern similar to that observed in non-ruminants.  相似文献   
112.
113.
Helms  CA; Sims  R 《Radiology》1986,160(1):153-154
A normal variant, the foraminal spur, is described in five patients. It was seen on computed tomographic studies as a bony process extending from either the pars or the pedicle into the neuroforamen dorsal to the nerve root. In four of the cases it was seen bilaterally. None of the patients had any symptoms related to these spurs. No associated disease of the neuroforamen or facet was present. These spurs most likely represent ossification of the ligamentum flavum at its point of insertion and should not be mistaken for osteophytes, free disk fragments that have calcified, or fracture fragments. Sagittal reformations are helpful in visualizing the extent of the foraminal spurs.  相似文献   
114.
115.

Background  

DNA fingerprinting of Mycobacterium tuberculosis isolates offers better opportunities to study links between tuberculosis (TB) cases and can highlight relevant issues in urban TB control in low-endemic countries.  相似文献   
116.
117.
Radioimmunoimaging of fresh canine venous thrombi with a murine monoclonal antibody specific for human and dog fibrin has been reported. Successful imaging of canine deep venous thrombi 1, 3, and 5 days old at the time of antibody injection is reported. Images were positive in all dogs, and the uptake of fibrin-specific antibody was equivalent to that of fresh thrombi.  相似文献   
118.
EJ Lee  ; CA Schiffer 《Transfusion》1989,29(5):384-389
Sixty consecutive patients with untreated acute leukemia alternately received either ABO-matched or ABO-mismatched random-donor platelet transfusions prepared from pooled platelet concentrate stored for 1 to 3 days. Patients were assigned randomly to receive matched or mismatched platelets as their first transfusion, and the first four transfusions were analyzed. In 40 evaluable patients, there was no significant difference (paired t test) between the 10-minute posttransfusion corrected count increments (CCI) of the initial transfusions of matched and mismatched platelets. In contrast, the second matched transfusion was significantly better than the second mismatched transfusion. This effect of ABO compatibility was particularly pronounced in a subset of patients. Six patients in whom mismatched transfusions were consistently inferior to matched transfusions had either a significant increase in anti-A or -B isoagglutinin titers following the first transfusion or elevated titers before or at the conclusion of the study. Conversely, in five patients in whom there was no apparent effect of ABO mismatching, only one had an increase in isoagglutinin titer. Platelet survival was not altered as the ratio of 18-hour to 10-minute posttransfusion CCl was 0.6 for both matched and mismatched platelet transfusions. These data demonstrate that ABO compatibility can affect the results of random-donor platelet transfusions and that patients who experience poor increments from ABO-mismatched platelets may benefit from a trial of ABO-compatible platelets before the initiation of HLA-matched platelet transfusion.  相似文献   
119.
SUMMARY Four cases of primary meningococcal conjunctivitis in children are reported. This represents an incidence of 2% of patients presenting with conjunctivitis to a paediatric A&E department. All were initially treated with topical chloramphenicol, followed by systemic rifampicin once the diagnosis had been established. No ocular or systemic complications developed, nor recolonisation of the conjunctiva or colonisation of the nasopharynx at follow-up (1–2 years).  相似文献   
120.
SUMMARY Clinically significant symptoms due to gastrointestinal metastases from primary lung cancers is rare. A case of life-threatening lower gastrointestinal haemorrhage secondary to metastatic squamous cell carcinoma of the lung is reported. Previous reports of such metastases are reviewed, with reference to management and prognosis. After resection of colonic metastases from squamous cell lung cancer, survival is similar to that for primary disease. It is suggested that patients with known or suspected squamous cell lung cancer presenting with lower gastrointestinal symptoms be managed as aggressively as those with no previous history of disease.  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