全文获取类型
收费全文 | 26607篇 |
免费 | 1856篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 194篇 |
儿科学 | 878篇 |
妇产科学 | 614篇 |
基础医学 | 3507篇 |
口腔科学 | 261篇 |
临床医学 | 3987篇 |
内科学 | 4688篇 |
皮肤病学 | 499篇 |
神经病学 | 2667篇 |
特种医学 | 489篇 |
外科学 | 2863篇 |
综合类 | 230篇 |
一般理论 | 41篇 |
预防医学 | 3475篇 |
眼科学 | 412篇 |
药学 | 1671篇 |
中国医学 | 20篇 |
肿瘤学 | 2016篇 |
出版年
2024年 | 31篇 |
2023年 | 249篇 |
2022年 | 362篇 |
2021年 | 796篇 |
2020年 | 587篇 |
2019年 | 763篇 |
2018年 | 913篇 |
2017年 | 672篇 |
2016年 | 705篇 |
2015年 | 714篇 |
2014年 | 1069篇 |
2013年 | 1521篇 |
2012年 | 2262篇 |
2011年 | 2338篇 |
2010年 | 1240篇 |
2009年 | 1092篇 |
2008年 | 1824篇 |
2007年 | 1919篇 |
2006年 | 1742篇 |
2005年 | 1625篇 |
2004年 | 1489篇 |
2003年 | 1299篇 |
2002年 | 1277篇 |
2001年 | 163篇 |
2000年 | 151篇 |
1999年 | 173篇 |
1998年 | 231篇 |
1997年 | 186篇 |
1996年 | 138篇 |
1995年 | 124篇 |
1994年 | 117篇 |
1993年 | 104篇 |
1992年 | 62篇 |
1991年 | 60篇 |
1990年 | 49篇 |
1989年 | 40篇 |
1988年 | 27篇 |
1987年 | 31篇 |
1986年 | 33篇 |
1985年 | 27篇 |
1984年 | 42篇 |
1983年 | 17篇 |
1982年 | 33篇 |
1981年 | 21篇 |
1980年 | 14篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1976年 | 18篇 |
1975年 | 15篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Peter MA Calverley Romain A Pauwels Paul W Jones Julie A Anderson J?rgen Vestbo 《INT J CHRONIC OBSTR》2006,1(3):209-218
Guidelines recommend that patients with COPD are stratified arbitrarily by baseline severity (FEV1) to decide when to initiate combination treatment with a long-acting β2-agonist and an inhaled corticosteroid. Assessment of baseline FEV1 as a continuous variable may provide a more reliable prediction of treatment effects. Patients from a 1-year, parallel-group, randomized controlled trial comparing 50 μg salmeterol (Sal), 500 μg fluticasone propionate (FP), the combination (Sal/FP) and placebo, (bid), were categorized post hoc into FEV1 <50% and FEV1 ≥50% predicted subgroups (n=949/513 respectively). Treatment effects on clinical outcomes – lung function, exacerbations, health status, diary card symptoms, and adverse events – were investigated. Treatment responses based on a pre-specified analysis explored treatment differences by severity as a continuous variable. Lung function improved with active treatment irrespective of FEV1; Sal/FP had greatest effect. This improvement appeared additive in milder disease; synergistic in severe disease. Active therapy significantly reduced exacerbation rate in patients with FEV1 <50% predicted, not in milder disease. Health status and breathlessness improved with Sal/FP irrespective of baseline FEV1; adverse events were similar across subgroups. The spirometric response to Sal/FP varied with baseline FEV1, and clinical benefits were not restricted to patients with severe disease. These data have implications for COPD management decisions, suggesting that arbitrary stratifications of baseline severity are not necessarily indicative of treatment efficacy and that the benefits of assessing baseline severity as a continuous variable should be assessed in future trials. 相似文献
62.
Robyn Stremler Ellen Hodnett Patricia Petryshen Bonnie Stevens Julie Weston Andrew R Willan 《分娩》2005,32(4):243-251
ABSTRACT: Background: Hands‐and‐knees positioning during labor has been recommended on the theory that gravity and buoyancy may promote fetal head rotation to the anterior position and reduce persistent back pain. A Cochrane review found insufficient evidence to support the effectiveness of this intervention during labor. The purpose of this study was to evaluate the effect of maternal hands‐and‐knees positioning on fetal head rotation from occipitoposterior to occipitoanterior position, persistent back pain, and other perinatal outcomes. Methods: Thirteen labor units in university‐affiliated hospitals participated in this multicenter randomized, controlled trial. Study participants were 147 women laboring with a fetus at ≥37 weeks’ gestation and confirmed by ultrasound to be in occipitoposterior position. Seventy women were randomized to the intervention group (hands‐and‐knees positioning for at least 30 minutes over a 1‐hour period during labor) and 77 to the control group (no hands‐and‐knees positioning). The primary outcome was occipitoanterior position determined by ultrasound following the 1‐hour study period and the secondary outcome was persistent back pain. Other outcomes included operative delivery, fetal head position at delivery, perineal trauma, Apgar scores, length of labor, and women's views with respect to positioning. Results: Women randomized to the intervention group had significant reductions in persistent back pain. Eleven women (16%) allocated to use hands‐and‐knees positioning had fetal heads in occipitoanterior position following the 1‐hour study period compared with 5 (7%) in the control group (relative risk 2.4; 95% CI 0.88–6.62; number needed to treat 11). Trends toward benefit for the intervention group were seen for several other outcomes, including operative delivery, fetal head position at delivery, 1‐minute Apgar scores, and time to delivery. Conclusions: Maternal hands‐and‐knees positioning during labor with a fetus in occipitoposterior position reduces persistent back pain and is acceptable to laboring women. Given this evidence, hands‐and‐knees positioning should be offered to women laboring with a fetus in occipitoposterior position in the first stage of labor to reduce persistent back pain. Although this study demonstrates trends toward improved birth outcomes, further trials are needed to determine if hands‐and‐knees positioning promotes fetal head rotation to occipitoanterior and reduces operative delivery. (BIRTH 32:4 December 2005) 相似文献
63.
64.
Julie C. Oki Pharm. D. 《Pharmacotherapy》1995,15(3):317-337
To characterize the lipid and lipoprotein abnormalities in patients with diabetes mellitus and evaluate the risks and benefits of marketed pharmacologic therapies, a MEDLINE search of the National Library of Medicine data base was performed of studies published from January 1966 to March 1994. Clinical trials assessing effects on lipids and lipoproteins, and adverse effects of marketed lipid-lowering agents were extracted. Reviews and other relevant articles were included if they provided information regarding lipid and lipoprotein metabolism or guidelines on the treatment of dyslipidemias in patients with diabetes mellitus. An extensive review of clofibrate was not included. The most common dyslipidemia in patients with poorly controlled insulin-dependent diabetes mellitus (IDDM) is combined elevated triglyceride and cholesterol levels, with reduced high-density lipoprotein (HDL) cholesterol (mixed hyperlipidemia). Hypertriglyceridemia combined with a reduced HDL cholesterol is the most common dyslipidemia in patients with noninsulin-dependent diabetes mellitus, but essentially any pattern of dyslipidemia may be present. Small and dense low-density lipoprotein (LDL), glycosylation of lipoproteins, and increased oxidized lipoproteins may be present in patients with diabetes mellitus; all contribute to accelerated atherosclerotic cardiovascular disease. Insulin therapy generally corrects quantitative lipid abnormalities in patients with IDDM, so drug treatment is seldom indicated. Diet, exercise, and insulin or oral sulfonylureas will improve hypertriglyceridemia and low HDL concentrations, but do not always return them to normal. Drug therapy is indicated when nonpharmacologic measures are inadequate. It is administered based on the effects of each agent on lipids and lipoproteins, patient age, adverse effect profile, patient tolerability, and drug-disease and drug-drug interactions. A fibric acid derivative is the drug of choice for marked hypertriglyceridemia in patients with diabetes mellitus. Niacin can worsen glycemic control, but it may be required in severe hypertriglyceridemia, hypercholesterolemia, or mixed hyperlipidemia. Bile-acid binding resins may accentuate hypertriglyceridemia but may be useful in selected patients with marked hypercholesterolemia and normal triglycerides. Hydroxymethylglutaryl coenzyme A reductase inhibitors are preferred in patients with elevated LDL cholesterol and mild hypertriglyceridemia. Patients with marked lipid abnormalities or mixed hyperlipidemias may require carefully dosed combinations of lipid-lowering drugs. 相似文献
65.
66.
67.
OBJECTIVES: To evaluate the demand for organs for transplantation and to recommend a reorganization of transplantation services in Quebec. DESIGN: Retrospective study. SETTING: Province of Quebec, 1988 to 1992. PATIENTS: All patients on waiting lists for organ transplantation and patients who received transplants registered in national data banks. MAIN OUTCOME MEASURES: The actual annual demand for organ transplantation and the rate of transplantations performed. RESULTS: The rates of heart transplantation were lower than the actual annual demand, which resulted in many patients dying while awaiting transplantation. The actual annual demand for heart transplantation decreased during the last 5 years from 10.9 per million people in 1987 to 6.7 in 1992. The rates of heart transplantation in Quebec were higher than the Canadian average. The actual demand for lung transplantation was only 2.9 per million people on average in 1992. Demand for liver transplantation increased annually, reaching 8.6 per million in 1992. The rate of transplantation increased likewise but remained insufficient. The demand for kidney transplantation reached 27.2 per million people in 1992, and the transplantation rate was 17.8. CONCLUSIONS: Taking into account the actual demand for and supply of organ transplantation, to insure high-quality service and to control costs associated with organ transplantation, we recommend that the present system in Quebec be reorganized so that transplantations are performed in 12 centres: 7 for kidney transplantation, 2 for hearts, 2 for livers and 1 for lungs. 相似文献
68.
69.
70.
Bertrand Marcheix Yoan Lamarche Pierre Perrault Raymond Cartier Denis Bouchard Michel Carrier Louis P. Perrault Philippe Demers 《European journal of cardio-thoracic surgery》2007,31(6):1004-1007
Objective: Whatever the surgical technique used, false aneurysm formation is one of the long-term complications of repair of aortic coarctation. Conservative management is associated with a 100% rate of rupture. The conventional surgical approach is complex and associated with high morbidity and mortality rates. We report our experience of endovascular management of pseudo-aneurysms after previous surgical repair of congenital aortic coarctation. Methods: Between October 2005 and 2006, stent-grafting of pseudo-aneurysms after previous surgical repair of congenital aortic coarctation was performed in four patients. Median age was 31.5 years (range: 24–38). Two patients had undergone two previous interventions. The last previous surgery consisted of graft interposition (N = 2), subclavian flap aortoplasty (N = 1) and aorto-aortic bypass (N = 1). Median size of the pseudo-aneurysm was 31.5 mm (range: 20–58). Mean time between the last surgery and endovascular treatment was 24 years (range: 3–32). One patient was treated emergently because of hemoptysis in relation with an aorto-bronchial fistula, the three other patients were treated electively. A transfemoral approach was used in all patients. The Zenith TX2® (Cook) thoracic stent-graft was used in all the patients, one patient underwent previous dilatation at the coarctation level. When present, the ostium of the left subclavian artery was always covered (N = 3). Results: No major complication occurred during the procedure and no patient died during the follow-up. One patient presented a type II endoleak which spontaneously healed during the first month. Another patient with his left subclavian artery covered presented claudication of the left arm requiring a carotid-subclavian bypass. After a median follow-up of 7.5 months (range: 1–12.9), the patients were asymptomatic and CT scans demonstrated complete exclusion of all treated postcoarctation aneurysms without recoarctation and without any stent-graft-related complication. Conclusions: The endovascular management of pseudo-aneurysms after previous surgical repair of congenital aortic coarctation is feasible. This approach was safe and effective. Long-term clinic and imaging follow-up is mandatory. 相似文献