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   1298篇
  免费   145篇
  国内免费   49篇
耳鼻咽喉   9篇
儿科学   100篇
妇产科学   17篇
基础医学   104篇
口腔科学   44篇
临床医学   113篇
内科学   396篇
皮肤病学   30篇
神经病学   24篇
特种医学   198篇
外科学   124篇
综合类   98篇
预防医学   75篇
眼科学   9篇
药学   72篇
中国医学   3篇
肿瘤学   76篇
  2023年   16篇
  2022年   13篇
  2021年   25篇
  2020年   21篇
  2019年   9篇
  2018年   21篇
  2017年   43篇
  2016年   39篇
  2015年   29篇
  2014年   66篇
  2013年   78篇
  2012年   31篇
  2011年   28篇
  2010年   65篇
  2009年   70篇
  2008年   29篇
  2007年   71篇
  2006年   43篇
  2005年   35篇
  2004年   28篇
  2003年   22篇
  2002年   19篇
  2001年   36篇
  2000年   22篇
  1999年   27篇
  1998年   86篇
  1997年   68篇
  1996年   61篇
  1995年   54篇
  1994年   46篇
  1993年   44篇
  1992年   16篇
  1991年   6篇
  1990年   18篇
  1989年   22篇
  1988年   29篇
  1987年   16篇
  1986年   22篇
  1985年   20篇
  1984年   11篇
  1983年   14篇
  1982年   9篇
  1981年   5篇
  1980年   9篇
  1979年   5篇
  1978年   6篇
  1977年   5篇
  1976年   12篇
  1975年   10篇
  1969年   3篇
排序方式: 共有1492条查询结果,搜索用时 15 毫秒
91.
92.
Recent observations suggest that first degree relatives of patients with an abdominal aortic aneurysm (AAA) are also at risk for the development of this disorder. The first degree relatives of 130 adults with known AAA were invited to attend for an ultrasound examination. Fifty-two eligible relatives (mean age 53 years, range 41–73) from 38 families underwent sonographic screening. Using standard ultrasound criteria no participants were identified with an asymptomatic AAA. Thus, ultrasound of families of patients with AAA has a low yield and may not be useful for screening purposes.  相似文献   
93.
OBJECTIVE: This study was undertaken to investigate the degeneration and calcification of valved bovine jugular vein segments for right ventricular outflow tract reconstruction in juvenile sheep. METHODS: Seven valved bovine jugular vein conduits (Contegra model 220; VenPro Corporation, Irvine, Calif) and 3 control conduits (MH100; Medtronic, Inc, Minneapolis, Minn) were implanted in the pulmonary artery in young sheep. After 20 weeks the conduits were explanted and qualitatively analyzed by epicardial echocardiography, gross examination, x-ray analysis, light microscopy, and transmission electron microscopy. Calcification was determined quantitatively by flame atomic absorption spectrometry. RESULTS: Two Contegra conduits could not be analyzed because of endocarditis. All other Contegra conduits functioned well, with preserved structure and minimal calcification. The control MH100 conduits exhibited extensive fibrous sheathing, with calcification of the aortic wall portion and the commissural part of the Hancock valve. CONCLUSIONS: The Contegra conduit's performance was clearly superior to that of the control MH100 conduit when implanted in the pulmonary artery position in juvenile sheep for 5 months.  相似文献   
94.
A 54-year-old patient with myelofibrosis developed paresis of the legs, and bladder dysfunction due to extramedullary haematopoiesis in the spinal channel. He was given palliative radiotherapy but died shortly afterwards. Although rare, the possibility of extramedullary haematopoiesis in the central nervous system should be considered when neurological symptoms appear in a patient with myelofibrosis, because good palliation is possible with timely radiotherapy.  相似文献   
95.
96.
97.
Hemolytic uremic syndrome spontaneously arises in a few patients with advanced cancer, but it is more commonly related to the use of certain chemotherapeutic agents. Mitomycin-C is, etiologically, the most common causative agent inducing hemolytic uremic syndrome, in a dose dependent manner. We report this syndrome, attributable to mitomycin-C at a cumulative dose of 40 mg/m2, in a gastric cancer patient. A 42-year-old female with stage III gastric cancer underwent radical gastrectomy and was given mitomycin-C at 10 mg/m2 intravenously every four weeks as adjuvant therapy. Hemolytic uremic syndrome was diagnosed three months after the last dose of mitomycin-C administration. The most prominent symptoms included pallor, hypertension and anasarca, with laboratory evidence of microangiopathic hemolytic anemia, azotemia and hyperkalemia. Her disease was progressive, but fortunately stabilized after staphylococcus column A dialysis. Her disease remained in remission for 24 months from the time of diagnosis, and then relapsed in the form of peritoneal carcinomatosis with partial intestinal obstruction.   相似文献   
98.
The benefits of achieving a long term event free survival of 60-70% by using increasingly intense treatment regimens must be weighed against the increased risk of treatment toxicity. From 1985 to 1990, 1612 children with childhood acute lymphoblastic leukaemia (ALL) in the UK were treated on MRC UKALL X with intensive induction therapy, central nervous system directed therapy (cranial irradiation and intrathecal methotrexate), and continuing treatment for two years. There was a randomisation to receive blocks of additional intensification treatment at five weeks, 20 weeks, not at all, or both. The five year disease free survival was 71% for children randomised to two blocks of intensification, a 14% improvement on children randomised to no intensification treatment. Treatment related mortality in this national multicentre study has been analysed for induction and first remission (including those after intensification treatment). There were 38 induction deaths, 2.3% and 53 deaths in first remission, 3.3% (including those from a second malignancy). Thirty one (84%) of the induction deaths followed an infection: bacterial in 22 and fungal in nine. Thirty seven infective remission deaths occurred: bacterial in 11, viral in 16, fungal in seven, and three caused by Pneumocystis carinii pneumonia. Ten of these deaths followed a block of intensification treatment. The majority of noninfective remission deaths followed the development of a second tumour. Risk analysis for an induction death showed girls and children with Down's syndrome to be at greater risk. For deaths in first remission analysis showed an increased risk for bone marrow transplant (BMT) patients and children with Down's syndrome. There was no effect of age and leucocyte count for either group. Most significantly when BMT patients were excluded from the analysis, intensification treatment did not increase the risk of remission death.  相似文献   
99.
100.
1. 5-Hydroxytryptamine (5-HT) exerts both contractile and relaxant effects in the marmoset isolated aorta, actions that are unaffected by the 5-HT2 antagonist ketanserin. The aim of the present study was to define the receptors mediating the contractile activity of 5-HT in the marmoset aorta.
2. Contractile responses were elicited in aortic rings that were either: (i) precontracted submaximally with the thromboxane A2 agonist U44069 in order to amplify the responses; or (ii) exposed to N ω-nitro- L -arginine (100 μmol/L) plus LY 53857 (0.1 μmol/L; a 5-HT2 receptor antagonist shown previously to inhibit relaxation). The effect of 5-HT on adenosine 3',5'-cyclic monophosphate (cAMP) formation was also investigated.
3. The effects of agonists and antagonists comprised: (i) agonist potencies in the order 5-carboxamidotryptamine > 5-HT > sumatriptan > 8-hydroxy-2-(di- n -propylamino)tetralin; (ii) inhibition of contractile action of 5-HT by the 5-HT1D antagonist GR 127935; (iii) a contractile response to methysergide; (iv) a lack of effect of tropisetron, an antagonist of 5-HT3 and 5-HT4 receptors; and (v) inhibition of forskolin-stimulated cAMP formation by 5-HT (in the presence of LY 53857), indicative of negative coupling to adenylate cyclase.
4. The above effects fulfil the criteria for a 5-HT1-like receptor. In view of the previous finding that this contractile response is insensitive to ketanserin, it is concluded that the contractile effects of 5-HT in the marmoset aorta are mediated exclusively by a 5-HT1-like receptor.  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