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   45633篇
  免费   2344篇
  国内免费   365篇
耳鼻咽喉   475篇
儿科学   911篇
妇产科学   1383篇
基础医学   5459篇
口腔科学   1742篇
临床医学   3527篇
内科学   12686篇
皮肤病学   941篇
神经病学   4041篇
特种医学   1209篇
外科学   6959篇
综合类   176篇
一般理论   10篇
预防医学   2472篇
眼科学   725篇
药学   2456篇
中国医学   116篇
肿瘤学   3054篇
  2023年   303篇
  2022年   281篇
  2021年   1452篇
  2020年   817篇
  2019年   1154篇
  2018年   1593篇
  2017年   1047篇
  2016年   1145篇
  2015年   1339篇
  2014年   1822篇
  2013年   2418篇
  2012年   3709篇
  2011年   3680篇
  2010年   2074篇
  2009年   1790篇
  2008年   3134篇
  2007年   3240篇
  2006年   3014篇
  2005年   2980篇
  2004年   2675篇
  2003年   2397篇
  2002年   2126篇
  2001年   324篇
  2000年   229篇
  1999年   321篇
  1998年   381篇
  1997年   330篇
  1996年   218篇
  1995年   284篇
  1994年   220篇
  1993年   169篇
  1992年   157篇
  1991年   113篇
  1990年   113篇
  1989年   98篇
  1988年   78篇
  1987年   79篇
  1986年   87篇
  1985年   85篇
  1984年   82篇
  1983年   75篇
  1982年   92篇
  1981年   63篇
  1980年   72篇
  1979年   45篇
  1978年   57篇
  1977年   47篇
  1976年   44篇
  1975年   32篇
  1974年   37篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
OBJECTIVES: The aim of this study was to evaluate the safety and effectiveness of laparoscopic-assisted sigmoid colectomy for diverticulitis and to assess its postoperative advantages. METHODS: From 1999 to 2001, 5 patients were selectively operated on with a laparoscopic-assisted procedure for uncomplicated sigmoid diverticulitis. In the preceding period (September 1997 through December 1998), 4 patients underwent open procedures for the same pathology. The surgical indication with the same criteria was restrictive: at least 2 acute episodes had occurred that were treated with hospital admission and that were separated by an adequate period (2 months) of medical therapy. RESULTS: No conversions of laparoscopy to an open procedure were necessary. Age, sex, weight, morbidity, and mortality were similar between the 2 groups. Operative time was 180 minutes for laparoscopy and 120 minutes for laparotomy. Postoperative resumption of peristalsis was 24 hours versus 4 days, resumption of alimentation was on the second postoperative day versus the fifth postoperative day, and hospital stay was 7 days versus 12 days for laparoscopy and laparotomy, respectively. CONCLUSION: This study shows the feasibility and the advantages of elective laparoscopic-assisted colonic resection for uncomplicated sigmoid diverticulitis. The advantages of the laparoscopic approach are the lower need for analgesics and the more precocious ambulation, canalization, resumption of alimentation, and the shorter hospital stay.  相似文献   
62.
63.
Background Cold ischemia time and the presence of postoperative hepatic arterial thrombosis have been associated with biliary complications (BC) after liver transplantation. An ABO-incompatible blood group has also been suggested as a factor for predisposal towards BC. However, the influence of Rh nonidentity has not been studied previously. Materials Three hundred fifty six liver transplants were performed from 1995 to 2000 at our hospital. BC incidence and risk factors were studied in 345 patients. Results Seventy patients (20%) presented BC after liver transplantation. Bile leakage (24/45%) and stenotic anastomosis (21/30%) were the most frequent complications. Presence of BC in Rh-nonidentical graft–host cases (23/76, 30%) was higher than in Rh-identical grafts (47/269, 17%) (P = 0.01). BC was also more frequent in grafts with arterial thrombosis (9/25, 36% vs 60/319, 19%; P = 0.03) and grafts with cold ischemia time longer than 430 min (26/174, 15% vs 44/171, 26%; P = 0.01). Multivariate logistic regression confirmed that Rh graft–host nonidentical blood groups [RR = 2(1.1–3.6); P = 0.02], arterial thrombosis [RR = 2.6(1.1–6.4); P = 0.02] and cold ischemia time longer than 430 min [RR = 1.8(1–3.2); P = 0.02] were risk factors for presenting BC. Conclusion Liver transplantation using Rh graft–host nonidentical blood groups leads to a greater incidence of BC.  相似文献   
64.

Background  

Total hip arthroplasty is a successful surgery, that fails at a rate of approximately 10% at ten years from surgery. Causes for failure are mainly aseptic loosening of one or both components partially due to wear of articular surfaces and partially to design. The present analysis aimed to identify risk factors and quantify their effects on aseptic failure.  相似文献   
65.
We propose a new self-organizing neural model that performs principal components analysis. It is also related to the adaptive subspace self-organizing map (ASSOM) network, but its training equations are simpler. Experimental results are reported, which show that the new model has better performance than the ASSOM network.  相似文献   
66.
67.
This study aimed to determine whether a weight-adjusted dose of subcutaneous enoxaparin is as effective and safe as oral acenocoumarol for the secondary prophylaxis of pulmonary embolism. Three hundred and eighty consecutive noncancer outpatients hospitalized with an episode of symptomatic pulmonary embolism selected treatment with acenocoumarol or enoxaparin at a dose of 1 mg/kg once daily after being informed of the type of administration and expected frequency of laboratory monitoring for both medicinal products. Endpoints were symptomatic recurrent thromboembolic events evaluated by standard objective testing, and a composite endpoint of recurrent venous thromboembolism, major bleeding, and death from any cause. One hundred and ninety-nine patients (52%) chose acenocoumarol therapy and 181 chose enoxaparin monotherapy. Four patients in the enoxaparin group (2.2%) and six patients in the acenocoumarol group (3%) had an objective thromboembolic recurrence (hazard ratio, 1.35; 95% confidence interval, 0.38-4.79; P = 0.64). Nine patients in the enoxaparin group (5.0%) had a hemorrhagic complication compared with 11 in the acenocoumarol group (5.5%) (P = 0.81). The hospital length of stay was shorter with enoxaparin compared with acenocoumarol (11 versus 16 days, P = 0.0001). Enoxaparin is as effective and safe as acenocoumarol in the secondary prevention of recurrent thromboembolic disease and is associated with shorter hospitalization.  相似文献   
68.
69.
BACKGROUND: The HOXA1 gene plays a major role in brainstem and cranial morphogenesis. The G allele of the HOXA1 A218G polymorphism has been previously found associated with autism. METHODS: We performed case-control and family-based association analyses, contrasting 127 autistic patients with 174 ethnically matched controls, and assessing for allelic transmission disequilibrium in 189 complete trios. RESULTS: A, and not G, alleles were associated with autism using both case-control (chi(2) = 8.96 and 5.71, 1 df, p <.005 and <.025 for genotypes and alleles, respectively), and family-based (transmission/disequilibrium test chi(2) = 8.80, 1 df, p <.005) association analyses. The head circumference of 31 patients carrying one or two copies of the G allele displayed significantly larger median values (95.0th vs. 82.5th percentile, p <.05) and dramatically reduced interindividual variability (p <.0001), compared with 166 patients carrying the A/A genotype. CONCLUSIONS: The HOXA1 A218G polymorphism explains approximately 5% of the variance in the head circumference of autistic patients and represents to our knowledge the first known gene variant providing sizable contributions to cranial morphology. The disease specificity of this finding is currently being investigated. Nonreplications in genetic linkage/association studies could partly stem from the dyshomogeneous distribution of an endophenotype morphologically defined by cranial circumference.  相似文献   
70.
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