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   938篇
  免费   24篇
  国内免费   75篇
耳鼻咽喉   1篇
儿科学   46篇
妇产科学   13篇
基础医学   69篇
口腔科学   15篇
临床医学   130篇
内科学   227篇
皮肤病学   34篇
神经病学   25篇
特种医学   257篇
外科学   44篇
综合类   28篇
预防医学   41篇
眼科学   22篇
药学   44篇
中国医学   3篇
肿瘤学   38篇
  2023年   5篇
  2021年   2篇
  2020年   4篇
  2019年   7篇
  2018年   7篇
  2017年   4篇
  2016年   9篇
  2015年   12篇
  2014年   15篇
  2013年   14篇
  2012年   12篇
  2011年   14篇
  2010年   31篇
  2009年   48篇
  2008年   15篇
  2007年   47篇
  2006年   17篇
  2005年   20篇
  2004年   9篇
  2003年   12篇
  2002年   12篇
  2001年   19篇
  2000年   20篇
  1999年   9篇
  1998年   82篇
  1997年   70篇
  1996年   59篇
  1995年   51篇
  1994年   43篇
  1993年   44篇
  1992年   21篇
  1991年   15篇
  1990年   22篇
  1989年   34篇
  1988年   34篇
  1987年   26篇
  1986年   22篇
  1985年   22篇
  1984年   18篇
  1983年   11篇
  1982年   17篇
  1981年   9篇
  1980年   13篇
  1979年   5篇
  1978年   6篇
  1977年   16篇
  1976年   13篇
  1975年   13篇
  1958年   2篇
  1900年   2篇
排序方式: 共有1037条查询结果,搜索用时 0 毫秒
991.
992.
The effect of intravenous 1-deamino (8-D-arginine)vasopressin (DDAVP) administration on platelet interaction with human artery subendothelium was investigated with flowing blood from five normal individuals and 12 patients with von Willebrand's disease (vWD). Three of the patients were diagnosed as vWD subtype I, four as subtype IIa, and five as subtype IIb. DDAVP administration to normals enhanced platelet adherence, in parallel with increasing plasma levels of factor VIII- related antigen ( FVIIIR :Ag) and ristocetin cofactor activity ( FVIIIR :RCF). Platelet aggregate formation was transiently increased within 90 minutes. Platelet adherence in patient blood before DDAVP infusion was subnormal. In patients with subtype I, administration of DDAVP normalized the bleeding time, enhanced the platelet adherence, and transiently improved the platelet aggregate formation. The platelet adherence was more corrected than would have been expected on the basis of the FVIIIR :Ag and FVIIIR :RCF levels. In patients with subtype IIa, infusion of DDAVP increased the FVIIIR :Ag levels approximately threefold, without affecting the FVIIIR :RCF levels, and in only two of four patients was a transiently enhanced platelet adherence with a corresponding shortening of the bleeding time observed. In patients with subtype IIb, administration of DDAVP increased the FVIIIR :Ag levels about threefold and the FVIIIR :RCF levels five to tenfold, but decreased the platelet adherence significantly. The bleeding time values were not normalized. A close association between the bleeding time values and corresponding platelet adherence values before and after DDAVP infusion was observed. Normalization of the bleeding time was paralleled with normalization of platelet adherence. We conclude that DDAVP improves the primary hemostasis by causing enhanced FVIII- vWF-mediated platelet adherence. DDAVP has little or no effect on the bleeding time in patients with subtype IIa and subtype IIb, because the platelet adherence is not normalized.  相似文献   
993.
Acne-associated spondylarthropathy: radiographic features   总被引:3,自引:0,他引:3  
Ellis  BI; Shier  CK; Leisen  JJ; Kastan  DJ; McGoey  JW 《Radiology》1987,162(2):541-545
Experience with six patients with severe acne and associated axial and peripheral arthritis is described. Four of the patients had a dermatologic triad of severe acne, hidradenitis suppurativa, and dissecting cellulitis of the scalp, the so-called follicular occlusion triad. All were black men with episodic peripheral arthropathy and low back pain. One had inflammatory bowel disease. Rheumatoid factor and HLA-B27 were absent in five patients who had these determinations. An erosive and proliferative arthritis of the axial and appendicular skeleton is described. The radiographic findings were indistinguishable from those of the seronegative spondylarthropathies. We found no previous reports in the radiologic literature describing this articulocutaneous entity.  相似文献   
994.
995.
应用分析型超临界流体萃取测定苏合香丸中主要成分   总被引:8,自引:0,他引:8  
利用分析型超临界流体萃取技术和GC/MS,GC/FID非在线偶合的方法测定了中成药苏合香丸提取物中主要的挥发性组分及其含量。本工作对超临界流体动态萃取过程影响萃取效率的主要因素,如压力、流体流过样品的体积等进行了考察,确定了适宜的操作条件。与传统方法比较,本方法具有更多的优点。  相似文献   
996.
997.
PURPOSE/METHODS: We present the case of a 69 year-old male patient who developed an anterior pole ischemia syndrome in his right eye. He did not have any personal history of diabetes or previous ocular pathology. Indirect ophthalmoscopy did not show any pathological finding. RESULTS/CONCLUSIONS: Carotid Duplex scanning and Nuclear Magnetic Resonance detected a severe carotid stenosis on the same side, which explained the case. We reviewed different forms of presentation of venous stasis syndrome in carotid stenosis and present this uncommon case of anterior segment ischemia syndrome without posterior segment findings.  相似文献   
998.
999.
The search for the carbohydrate-deficient glycoprotein syndrome type I (CDG1) gene has revealed the existence of a family of phosphomannomutase (PMM) genes in humans. Two expressed PMM genes, PMM1 and PMM2 , are located on chromosome bands 22q13 and 16p13, respectively, and a processed pseudogene PMM2 psi is located on chromosome 18p. Mutations in PMM2 are the cause of CDG type IA whereas no disorder has been associated with defects in PMM1 as yet. Here, we describe the genomic organization of these paralogous genes. There is a 65% identity of the coding sequence, and all intron/exon boundaries have been conserved. The processed pseudogene is more closely related to PMM2 . Remarkably, several base substitutions in PMM2 that are associated with disease are also present at the corresponding positions in the pseudogene. Thus, mutations that occur at a slow rate in the active gene in the population have also accumulated in the pseudogene.   相似文献   
1000.
To determine the risks when the primary methotrexate (MTX) treatment of cervical pregnancy has an unsatisfactory outcome, we conducted a Medline search on relevant literature published from January 1983 to June 1997. The search yielded 28 publications of 48 cases of cervical pregnancy. These and four new cases from our institutions were used in our study. A cervical pregnancy that presented with a serum beta-human chorionic gonadotrophin concentration of > or = 10,000 mIU/ml [odds ratio (OR) 10.82, 95% confidence interval (CI) 2.59, 45.14], gestational age at > or = 9 weeks (OR 6.44, 95% CI 1.46, 28.52), embryonic cardiac activity (OR 14.29, 95% CI 2.95, 76.92), and crown- rump length of >10 mm (OR 13.33, 95% CI 1.46, 120.48) was considered to be associated with a higher unsatisfactory rate of primary MTX treatment. A concomitant feticide was found to enhance the therapeutic effect of MTX treatment if embryonic cardiac activity was evident (OR 0.13, 95% CI 0.02, 0.68). Administration of a high dose of MTX did not seem to be more effective than a lower one. Our findings supported some previous observations and, more importantly, provided useful clinical information in selecting appropriate candidates for MTX treatment in cases of cervical pregnancy.   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