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   271914篇
  免费   15136篇
  国内免费   7597篇
耳鼻咽喉   3119篇
儿科学   8954篇
妇产科学   3210篇
基础医学   22785篇
口腔科学   8025篇
临床医学   31146篇
内科学   43040篇
皮肤病学   3158篇
神经病学   12010篇
特种医学   16169篇
外国民族医学   22篇
外科学   51639篇
综合类   25284篇
现状与发展   27篇
预防医学   16420篇
眼科学   4492篇
药学   25630篇
  112篇
中国医学   5908篇
肿瘤学   13497篇
  2023年   2629篇
  2022年   5509篇
  2021年   12018篇
  2020年   6959篇
  2019年   12495篇
  2018年   7427篇
  2017年   6482篇
  2016年   8547篇
  2015年   11459篇
  2014年   20977篇
  2013年   18963篇
  2012年   21320篇
  2011年   18422篇
  2010年   16794篇
  2009年   16499篇
  2008年   15055篇
  2007年   15121篇
  2006年   13048篇
  2005年   9207篇
  2004年   5455篇
  2003年   4637篇
  2002年   3697篇
  2001年   3112篇
  2000年   2834篇
  1999年   2033篇
  1998年   2327篇
  1997年   2142篇
  1996年   1711篇
  1995年   1715篇
  1994年   1592篇
  1993年   1300篇
  1992年   1466篇
  1991年   1255篇
  1990年   1271篇
  1989年   1222篇
  1988年   1153篇
  1987年   1014篇
  1986年   849篇
  1985年   1762篇
  1984年   1883篇
  1983年   1346篇
  1982年   1474篇
  1981年   1440篇
  1980年   1243篇
  1979年   1102篇
  1978年   852篇
  1977年   844篇
  1976年   723篇
  1974年   472篇
  1973年   474篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
102.
103.

Background

Arterial vascular anomalies in patients undergoing kidney transplantation (KT) are correlated with a higher incidence of early surgical complications, potentially causing graft loss. Arterial reconstruction allows patients to overcome these surgical challenges, thus minimizing the risk of poor outcomes. The aim of the present study is to retrospectively investigate the safety and effectiveness of the multiple arterial reconstruction technique with a Teflon patch in case of an unavailable aortic patch: to do so, surgical complications, graft function, and patient survival were evaluated.

Methods

During the period January 2009 to August 2016, 202 adult deceased-donor KTs were performed at our center. Group A (n = 27; reconstruction of multiple arteries) and Group B (n = 175; control group) were compared.

Results

No differences were observed between the 2 groups in terms of early postoperative course, with no vascular complication observed in Group A. No vascular patch infections were reported, nor longer cold ischemia time rates. Similarly, long-term survival rates were similar between the 2 groups.

Conclusions

The Teflon-patch arterial reconstruction technique appears to be safe and effective, with an acceptable balance of benefits and potential risks of using a prosthetic material. Studies based on larger series are needed to further validate this approach.  相似文献   
104.
Patients with mechanic ankle instability experience increased tibiotalar and subtalar joint laxity. However, in vivo joint kinematics in functional ankle instability (FAI) patients and lateral ankle sprain (LAS) copers, especially during dynamic activities, are poorly understood. Ten FAI patients, 10 LAS copers, and 10 healthy controls were included in this study. A dual fluoroscopic imaging system was used to analyze the tibiotalar and subtalar joint kinematics during stair descent. Five key poses of stair descent were analyzed. Kinematic data from six degrees of freedom were calculated utilizing a solid modeling software. The range of motion and joint positions in each degree of freedom were compared among the three groups. The tibiotalar joints of FAI patients and LAS copers were significantly more inverted than those of healthy controls during the foot strike (p = 0.016, = 0.264). The subtalar joints of FAI patients were significantly more anteriorly translated (pose 2, p = 0.003, = 0.352; pose 3, p < 0.001, = 0.454; pose 4, p = 0.004, = 0.334), inverted (pose 4, p = 0.027, = 0.234; pose 5,p = 0.034, = 0.221), and externally rotated (pose 4, p = 0.037, = 0.217; pose 5; p = 0.004, = 0.331) than those of healthy controls during the mid‐stance and the heel off. The FAI patients showed excessive tibiotalar inversion and subtalar joint hypermobility during stair descent. Meanwhile, the LAS copers maintained subtalar joint stability, and only showed excessive tibiotalar inversion in foot strike. These data provide insight into the mechanisms behind the development of FAI after initial LAS. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1860–1867, 2019  相似文献   
105.
目的对中国精神分裂症患者采取家庭干预的研究文献进行综合回顾和系统评价, 比较不同条件下家庭干预效果的差异。方法在中国知网、维普、万方、中国生物医学文献数据库四大中文数据库及OVID Medline、Science Direct、Web of Science、EBSCO四大英文数据库中, 检索各数据库建库至2015年1月为止使用社会功能缺陷筛选量表(SDSS)、简明精神病(科)量表(BPRS)、阳性与阴性症状量表(PANSS)研究中国精神分裂症患者家庭干预效果的文献, 以标准化加权均数差( SMD)作为效应量, 采用meta分析比较不同干预时间、不同干预类型、对不同病程和不同严重程度的精神分裂症患者的家庭干预效果差异。 结果共纳入57篇符合标准的文献。SDSS、PANSS分析结果显示:① 干预时间越长干预效果越好( P < 0.0001、 P=0.0025);② 单独家庭干预比多个家庭合并单独家庭干预的效果更明显( P < 0.0001、 P=0.0131);③ 干预对于病情较重患者效果较好( P < 0.0001、 P=0.0280)。SDSS量表还显示家庭干预对于病程短的患者效果更好( P < 0.0001)。 结论家庭干预更适合病程较短的精神分裂症患者, 干预应实施较长时间; 单独家庭干预更有利于患者阴性症状的改善和社会功能的康复, 且对于病情较轻患者的阴性症状改善效果更好。  相似文献   
106.
ObjectivesThis study aimed to determine the effect of lower leg compression during cesarean section (CS) on post-spinal hypotension (PSH) and neonatal hemodynamic parameters.MethodsThis study is a nonrandomized controlled clinical trial conducted in the cesarean delivery unit of the National Medical institute, Damanhour, Egypt. The sample included 120 parturients (60 intervention and 60 control). The researchers developed three tools for data collection: sociodemographic data and reproductive history interview schedule, electronic monitoring of maternal hemodynamic parameters, and neonatal hemodynamic assessment sheet. All parturients received ordinary pre-operative care. For the intervention group, a long elastic stocking (ordinary pressure 20–30 mmHg, 1 mmHg = 0.133 kPa) was applied on both legs during cesarean section. The control group received the same care without the elastic stocking.ResultsSystolic blood pressure, diastolic blood pressure, and mean arterial blood pressure were significantly higher in the intervention group throughout the entire operation period except in the last 5–15 min. Heart rate was significantly lower in the intervention group. Only 13.3% of the intervention group took ephedrine compared with 45% of the control group. Apgar score was higher among neonates of intervention group compared with the control group at 1 min. Neonatal acidosis was significantly higher in the control group than in the contral group.ConclusionLower leg compression technique can effectively reduce PSH and neonatal acidosis.  相似文献   
107.
108.
The serrated pathway (SP) can be viewed as two parallel, but partially overlapping, arrays of colorectal precursor lesions, and their respective endpoint carcinomas, that are distinct from those of the conventional adenoma–carcinoma sequence (APC‐pathway). In this review we focus at the outset on the clinical impact, pathological features, molecular genetics and biological behaviours of the various SP cancers. Then we summarize the clinicopathological features, classification and molecular profiles of the two main precursor lesions that anchor the respective pathways: (i) sessile serrated adenoma/polyp (SSA/P), also called sessile serrated lesion (SSL), and (ii) traditional serrated adenoma (TSA). Activating mutations of the RAS–RAF–MAPK pathway initiate and sustain the lesions of the SP, and CpG island methylation of the promoter regions of tumour suppressor and DNA repair genes play the major role in their neoplastic progression. The SP includes microsatellite stable (MSS) carcinomas that are among the most biologically aggressive colorectal carcinomas (CRC), and also accounts for the great preponderance of sporadic hypermutated, mismatch repair (MMR)‐deficient or microsatellite instable (MSI) CRC. The identification, removal and appropriate classification of at‐risk SP precursors and surveillance of individuals who harbour these lesions present a challenge and opportunity for CRC prevention and mortality reduction.  相似文献   
109.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic.  相似文献   
110.
PurposeTo evaluate the potential differences in non-target embolization and vessel microsphere filling of a reflux-control microcatheter (RCM) compared to a standard end-hole microcatheter (SEHM) in a swine model.Materials and methodsRadiopaque microspheres were injected with both RCM and SEHM (2.4-Fr and 2.7-Fr) in the kidneys of a preclinical swine model. Transarterial renal embolization procedures with RCM or SEHM were performed in both kidneys of 14 pigs. Renal arteries were selectively embolized with an automated injection protocol of radio-opaque microspheres. Ex-vivo X-ray microtomography images of the kidneys were utilized to evaluate the embolization by quantification of the deposition of injected microspheres in the target vs. the non-target area of injection. X-ray microtomography images were blindly analyzed by five interventional radiologists. The degree of vessel filling and the non-target embolization were quantified using a scale from 1 to 5 for each parameter. An analysis of variance was used to compare the paired scores.ResultsTotal volumes of radio-opaque microspheres injected were similar for RCM (11.5 ± 3.6 [SD] mL; range: 6–17 mL) and SEHM (10.6 ± 5.2 [SD] mL; range: 4–19 mL) (P = 0.38). The voxels enhanced ratio in the target (T) vs. non-target (NT) areas was greater with RCM (T = 98.3% vs. NT = 1.7%) than with SEHM (T = 89% vs. NT = 11%) but the difference was not significant (P = 0.30). The total score blindly given by the five interventional radiologists was significantly different between RCM (12.3 ± 2.1 [SD]; range: 6–15) and the standard catheter (11.3 ± 2.5 [SD]; range: 4–15) (P = 0.0073), with a significant decrease of non-target embolization for RCM (3.8 ± 1.3 [SD]; range: 3.5–4.2) compared to SEHM (3.2 ± 1.5 [SD]; range: 2.9–3.5) (P = 0.014).ConclusionIn an animal model, RCM microcatheters reduce the risk of non-target embolization from 11% to 1.7%, increasing the delivery of microspheres of 98% to the target vessels, compared to SEHM microcatheters.  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