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   17702篇
  免费   1336篇
  国内免费   52篇
耳鼻咽喉   251篇
儿科学   404篇
妇产科学   260篇
基础医学   2140篇
口腔科学   276篇
临床医学   2020篇
内科学   3813篇
皮肤病学   250篇
神经病学   1460篇
特种医学   620篇
外科学   3296篇
综合类   217篇
一般理论   22篇
预防医学   1406篇
眼科学   336篇
药学   1139篇
中国医学   11篇
肿瘤学   1169篇
  2023年   210篇
  2022年   404篇
  2021年   874篇
  2020年   438篇
  2019年   666篇
  2018年   761篇
  2017年   502篇
  2016年   545篇
  2015年   628篇
  2014年   863篇
  2013年   962篇
  2012年   1544篇
  2011年   1554篇
  2010年   786篇
  2009年   633篇
  2008年   1096篇
  2007年   1041篇
  2006年   878篇
  2005年   792篇
  2004年   684篇
  2003年   633篇
  2002年   488篇
  2001年   147篇
  2000年   139篇
  1999年   130篇
  1998年   97篇
  1997年   74篇
  1996年   55篇
  1995年   45篇
  1994年   38篇
  1993年   50篇
  1992年   68篇
  1991年   78篇
  1990年   71篇
  1989年   69篇
  1988年   65篇
  1987年   61篇
  1986年   70篇
  1985年   77篇
  1984年   61篇
  1983年   55篇
  1982年   38篇
  1981年   47篇
  1980年   34篇
  1979年   46篇
  1978年   45篇
  1976年   45篇
  1974年   33篇
  1971年   35篇
  1966年   33篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
The Australian Leukaemia Study Group myeloma study (MM1) aimed to determine the prognostic significance of clinical and immunophenotypic markers in patients with multiple myeloma. All patients were treated with standard dose melphalan and prednisone. Seventy-four patients were entered and the median survival was 27 months. Serum beta 2-microglobulin (βM) and albumin levels were the only significant clinical factors influencing survival (p = 0.007 and p = 0.008, respectively). Patients with raised levels of CD38+ lymphocytes at presentation had a significantly shorter survival than patients with normal levels (p = 0.01, logrank test, median 19 months vs 33 months). CD38 antigen expression was independent of β2M but patients with raised levels of CD38 had significantly lower levels of albumin than patients with normal levels (p = 0.001) which may explain their poorer survival. Salmon and Durie stage was not associated with antigen expression. No other B-cell antigens (CD10, CD19, CD20, CD21, CD22, CD23, FMC1 or FMC7) or plasma cell antigens tested (PCA-1) were found to be associated with prognosis. Patients who achieved plateau phase had a better prognosis than those who did not (p = 0.04 in a landmark analysis). Patients who achieved plateau phase following an objective response appeared to have a better prognosis than those who were in plateau phase at presentation (p = 0.09 in a landmark analysis). Light chain isotype suppression (LCIS) was not associated with a significant survival advantage and did not correlate with any known prognostic indicator. We conclude that phenotypic analysis of peripheral blood lymphocytes for CD38 antigen at diagnosis may be useful as a prognostic indicator in patients with myeloma.  相似文献   
32.
Neonatal septicaemia (NNS) is a major cause of neonatal morbidity and mortality. Neonatal septicaemia was studied to determine the incidence, common bacterial aetiology and antibiotic susceptibility in Qatif Central Hospital, Saudi Arabia. Of 1,797 babies admitted into the unit over a 3 year period, 144 (8.0%) had documented neonatal septicaemia consisting of 94 (65%) late onset and 50 (35%) early onset septicaemia. The incidence was 8.2/1000 of the total live births in the hospital.

Gram negative bacteria were encountered in 66.2%, gram positive bacteria in 29.2% and Candida albicans in 4.4% of the case. Klebsiella spp., E. coli, and Pseudomonas accounted for 81.8 % of the gram negative while Staphylococcus epidermidis, Staphylococcus aureus and group B Beta haemolytic Streptococcus accounted for 73.9% of the gram positive bacteria.

Most of Gram negative bacteria had a high sensitivity to Aminoglycosides and third generation Cephalosporins. Coagulase negative staphylococci were frequently resistant to most antibiotics but always sensitive to Vancomycin. The overall mortality rate was 18.7%.  相似文献   
33.
The present study is a quantitative analysis of the unmyelinated fiber population in the fasciculus gracilis of the second cervical segment of cat and monkey. We find that unmyelinated fibers represent 13.7% of the total fiber population in this pathway in the cat and 18.9% in the monkey (Macaca fascicularis). The existence of such large numbers of these axons suggests that there may be a sizeable ascending fine primary afferent pathway in the fasciculus gracilis in cat and monkey whose destination is presumably the dorsal column nuclei. These findings are of interest in regard to classic ideas that the afferent fibers in the dorsal columns are large myelinated fibers that convey fine discriminative information to the dorsal column nuclei.  相似文献   
34.
35.
The case of a 57-year-old man with chondrosarcoma of the laryngeal cartilage is presented, occurring 16 years after radiation treatment for squamous cell carcinoma of the right true vocal cord. Chondrosarcoma of the larynx is an uncommon tumor. The location, grade, and time elapsed from initial treatment make it probably that this patient's chondrosarcoma is associated with his prior radiation treatment. However, it is a rare occurrence, this being the second case reported in the literature.  相似文献   
36.
37.
Background. The optimal management of patients with renal cell carcinoma with inferior vena cava tumor thrombus remains unresolved. Traditional approaches have included resection with or without the use of cardiopulmonary bypass. Chemotherapy has played a minor role except for biotherapeutic agents used for metastatic disease.

Methods. From January 1989 to January 1996, 37 patients with renal cell carcinoma and inferior vena cava tumor thrombus underwent surgical resection. The 27 men and 10 women had a median age of 57 years (range, 29 to 78 years). Thirty-six patients presented with symptoms; 21 had hematuria. Distant metastases were present in 12 patients. Tumor thrombi extended to the infrahepatic inferior vena cava (n = 16), the intrahepatic inferior vena cava (n = 16), the suprahepatic inferior vena cava (n = 3), and into the right atrium (n = 2). All tumors were resected by inferior vena cava isolation and, when necessary, extended hepatic mobilization and Pringle maneuver, with primary or patch closure of the vena cavotomy. Cardiopulmonary bypass was necessary in only 2 patients with intraatrial thrombus.

Results. Complications occurred in 11 patients, and 1 patient died 2 days postoperatively of a myocardial infarction (mortality, 2.7%). Twenty patients are alive; overall 2- and 5-year survival rates were 61.7% and 33.6%, respectively. For patients without lymph node or distant metastases (stage IIIa), 2- and 5-year survival rates were 74% and 45%, respectively. The presence of distant metastatic disease (stage IV) at the time of operation did not have a significant adverse effect on survival, as reflected by 2- and 5-year survival rates of 62.5% and 31.3%, respectively. Lymph node metastases (stage IIIc) adversely affected survival as there were no long-term survivors.

Conclusions. Resection of an intracaval tumor thrombus arising from renal cell carcinoma can be performed safely and can result in prolonged survival even in the presence of metastatic disease. In our experience, extracorporeal circulatory support was required only when the tumor thrombus extended into the heart.  相似文献   

38.
39.
40.
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