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   32822篇
  免费   2299篇
  国内免费   334篇
耳鼻咽喉   337篇
儿科学   734篇
妇产科学   802篇
基础医学   4174篇
口腔科学   1024篇
临床医学   3382篇
内科学   6670篇
皮肤病学   327篇
神经病学   3140篇
特种医学   1100篇
外国民族医学   1篇
外科学   4518篇
综合类   1109篇
一般理论   33篇
预防医学   3120篇
眼科学   760篇
药学   2169篇
  4篇
中国医学   210篇
肿瘤学   1841篇
  2023年   237篇
  2022年   378篇
  2021年   783篇
  2020年   515篇
  2019年   648篇
  2018年   801篇
  2017年   651篇
  2016年   661篇
  2015年   823篇
  2014年   1041篇
  2013年   1422篇
  2012年   2037篇
  2011年   2360篇
  2010年   1424篇
  2009年   1215篇
  2008年   1882篇
  2007年   2138篇
  2006年   1891篇
  2005年   1860篇
  2004年   1797篇
  2003年   1689篇
  2002年   1559篇
  2001年   687篇
  2000年   606篇
  1999年   609篇
  1998年   369篇
  1997年   287篇
  1996年   247篇
  1995年   230篇
  1994年   216篇
  1993年   195篇
  1992年   321篇
  1991年   305篇
  1990年   277篇
  1989年   271篇
  1988年   253篇
  1987年   204篇
  1986年   195篇
  1985年   204篇
  1984年   156篇
  1983年   155篇
  1982年   121篇
  1981年   103篇
  1980年   88篇
  1979年   100篇
  1978年   109篇
  1977年   91篇
  1976年   77篇
  1975年   117篇
  1974年   91篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
BACKGROUND: Cardiac magnetic resonance (MR) images are often reviewed by non-cardiologists who are not trained in the interpretation of regional left ventricular (LV) function. We hypothesized that the use of still-frame parametric MR images of wall motion could aid in the assessment of regional LV function. METHODS: Dynamic, electrocardiogram-gated, steady-state free precession (FIESTA) short-axis images were obtained in 6 to 10 slices in 18 consecutive patients. Each loop was used to automatically generate a still-frame image, in which each pixel is assigned a value equal to the amplitude of cyclic variation in local intensity, resulting in higher intensity in pixels that change between blood and tissue during the cardiac cycle. The dynamic images were reviewed by an expert cardiologist who provided gold standard grades for regional wall motion and by four radiologists. Then the radiologists reviewed and graded the same MR images in combination with parametric images. Grades assigned to each segment in the two sessions were compared with the gold standard. RESULTS: According to expert interpretation, 6 patients had normal wall motion, and 12 had wall motion abnormalities. Parametric images showed a bright band in the area spanned by endocardial motion, with reduced brightness and thickness in areas of hypokinesis. The agreement between the radiologists' grades and the gold standard significantly improved by adding parametric images (from 77% to 81%), which also resulted in reduced interobserver variability (from 52% to 33%). CONCLUSIONS: Still-frame parametric images aid in the assessment of regional wall motion by non-cardiologists who are required to interpret cardiac images.  相似文献   
33.
目的观察急性冠状动脉综合征患者介入治疗后血小板活化指标CD62p、CD63及糖蛋白Ⅱb/Ⅲa受体复合物及内皮功能的改变。方法60例急性冠状动脉综合征患者在冠状动脉介入术前和术后即刻以及次日采用流式细胞仪检测血小板活化指标CD62p、CD63及糖蛋白Ⅱb/Ⅲa受体复合物;双抗体夹心固相酶联免疫吸附试验测定血浆假血友病因子的表达水平;放射免疫测定法测定血浆内皮素1表达水平;酶法测定血浆一氧化氮的含量;彩色多谱勒超声诊断仪测量内皮依赖性血管舒张功能。选择健康体检者和稳定型心绞痛患者各30例作对照,观察急性冠状动脉综合征患者冠状动脉介入前后指标的变化并与对照组比较。结果与健康对照组和稳定型心绞痛组比,急性冠状动脉综合征组CD62p、CD63及糖蛋白Ⅱb/Ⅲa受体复合物明显增高(P<0.05或0.01);急性冠状动脉综合征患者介入术后即刻CD62p、CD63和糖蛋白Ⅱb/Ⅲa受体复合物与术前相比明显增高(P<0.01),但术后24h较术前无明显变化(P>0.05)。与健康对照组和稳定型心绞痛组比,急性冠状动脉综合征组假血友病因子、内皮素1的表达水平明显增高(P<0.01),内皮依赖性血管舒张功能和一氧化氮降低(P<0.05或<0.01);急性冠状动脉综合征患者介入术后即刻血浆假血友病因子和内皮素1水平升高(P<0.05或P<0.01),内皮依赖性血管舒张功能和一氧化氮水平降低(P<0.05),且介入术后24h假血友病因子水平也较术前升高(P<0.05),内皮依赖性血管舒张功能降低(P<0.05),但内皮素1和一氧化氮水平与术前差异无显著性(P>0.05)。结论血小板活化和内皮功能的损伤在急性冠状动脉综合征发生和发展过程中起重要的作用,冠状动脉介入术后血管内皮受到一定损伤,血小板有一定程度的激活。  相似文献   
34.
OBJECTIVES: To present a single centers' 7-year experience in the endovascular treatment of acute traumatic lesions of the descending thoracic aorta (ATL of the DTA). MATERIALS & METHODS: Between March 1999 and December 2006, 34 consecutive acute traumatic lesions of the descending aorta (23 men, mean age 44 years) were treated endovascularly. Stentgrafts used were TAG Excluder, Zenith TX2 and Talent. In 23 patients the Left Subclavian Artery (LSA) was covered. Mean procedural duration was 20 to 75 minutes. RESULTS: Exclusion of the rupture site was achieved in all cases with no conversion to open surgery. Overall 30-day mortality was 8.8%. Two patients died on post operative day (pod) 1 and one on pod 22 from cranial injuries. No death or neurological deficit related to the endovascular treatment was reported. Four type I endoleaks required treatment either by balloon reexpansion (n=2) or by additional stentgraft implantation (n=2). In two patients the stentgraft collapsed totally several days postoperatively. Two patients required secondary surgical procedures (iliac access complication and revascularisation of the left subclavian artery n=1). The average follow-up was 43.8 months (1-93 months). No stentgraft related abnormality has been subsequently documented. CONCLUSIONS: The endovascular treatment of ATL of the DTA may offer the best means of therapy in a polytrauma patient.  相似文献   
35.
阴茎勃起神经再生模型和机制的研究   总被引:1,自引:0,他引:1  
探明神经性勃起功能障碍(NED)的分子生物学机制以期对该类疾病进行神经调控干预,是男科学研究的当务之急。本文回顾了急性神经损伤、前列腺癌、糖尿病和帕金森病所致的NED的研究进展。通过利用大鼠阴茎勃起神经的盆腔大神经节(MPG),在体外构建一个三维培养体系来研究各种生长因子和细胞信号通路对神经再生的影响。体外结果表明脑源性神经生长因子(BDNF)通过JAK/STAT信号通路可显著促进NED的恢复,并在体内证实了该效应。因此,通过调控JAK/STAT信号通路来达到神经调控干预措施预防治疗神经性勃起功能障碍成为可能。  相似文献   
36.
Objectives Cutaneous burns are dynamic injuries with a central zone of necrosis surrounded by a zone of ischemia. Conversion of this ischemic zone to full necrosis over the days following injury is due in part to highly reactive oxygen radicals. Curcumin is a component of the Oriental spice turmeric that has been shown to have antioxidant and antiapoptotic properties. The authors hypothesized that treatment of burns with curcumin would reduce the conversion of the ischemic zone to full necrosis. Methods This was a randomized controlled experiment. Twenty Sprague‐Dawley rats were used. Two burns were created on each animal's dorsum using a brass comb with four rectangular prongs preheated in boiling water and applied for 30 seconds, resulting in four rectangular 10 × 20–mm full‐thickness burns separated by three 5 × 20–mm unburned interspaces (zone of ischemia). Animals were randomized to curcumin or vehicle by oral gavage 30 minutes before injury and at 24, 48, and 72 hours after injury. Wounds were observed at one, two, and three days after injury for visual evidence of necrosis in the unburned interspaces. Full‐thickness biopsy specimens from the interspaces were evaluated with hematoxylin and eosin staining seven days after injury for evidence of necrosis. The percentage of interspaces that progressed to necrosis was compared with chi‐square tests. Results Forty comb burns with 120 unburned interspaces were created, evenly distributed between curcumin and vehicle alone. The percentage of interspaces that progressed to full‐thickness necrosis at one, two, three, and seven days after injury in the curcumin and vehicle groups were 30% versus 63% (p = 0.003), 30% versus 70% (p < 0.001), 63% versus 95% (p = 0.02), and 63% versus 95% (p = 0.02), respectively. Conclusions Pretreatment of rats with oral curcumin followed by once‐daily oral treatment for three days reduced the percentage of unburned skin interspaces that progressed to full necrosis.  相似文献   
37.
Government reform of the NHS in the UK has sought to increase the involvement of doctors (clinicians) in hospital management. Using frameworks from the psychological contract and organisational misbehaviour literatures, this paper examines the processes involved when clinicians assume management roles. This literature seeks to explain breaches to expectations regarding prior agreements with management and subsequent actions of 'getting even' as a result of breaches to the employment relationship. A qualitative methodology using interviews was undertaken, which identified two distinct groups of clinician-manager. Investors actively pursued a management opportunity as an alternative to clinical medicine, whilst reluctants tended to assume a management role to protect particular specialities from outside influence or from those they thought would be inappropriate clinician-managers. Investors and reluctants often had very little prior experience of management and managers and had problems reconciling their dual clinician-management role. Poor relationships with hospital managers who often had no understanding of their dual responsibilities led to tensions and conflict, which questions continued developments in this important area of UK health policy. Suggestions for improving this process are outlined.  相似文献   
38.
[目的]探讨外固定支架结合骨折端局部注射自体骨髓多能干细胞治疗桡骨远端粉碎性骨折的有效性。[方法]应用外固定支架结合骨折端局部注射自体骨髓多能干细胞治疗桡骨远端粉碎性骨折18例。[结果]随访6~15个月(平均8个月),优10例,良6例,可2例,差0例。优良率为88.9%。没有一例出现针道浅表感染等并发症。[结论]外固定支架结合骨折端局部注射自体骨髓多能干细胞是治疗桡骨远端粉碎性骨折的一种方便、有效的方法,不仅骨折愈合效果满意,而且固定确实可靠,并能早期功能调整和训练。  相似文献   
39.
目的 探讨慢性非细菌性前列腺炎(CNP)和前列腺痛(PD)的治疗方法。方法 应用体外短波热疗联合前列腺灸及α1A-肾上腺素能受体阻滞剂哈乐治疗CNP和PD患者26例,疗程8周。观察治疗前后前列腺炎症状评分(CPSI)与最大尿流率(MFR)变化。结果 有效率为80.8%。治疗前后CPSI和MFR均有显著改善(P〈0.05)。结论 体外短波热疗联合前列腺灸及哈乐治疗CNP和PD安全有效。  相似文献   
40.
An 11‐year‐old Gordon setter bitch was presented with a history of progressive weakness in the right hind limb associated with pain in the lumbar spine. Neurological deficits consisted of ataxia, monoparesis, muscle atrophy and spontaneous over‐knuckling of the affected limb. A large ‘juxtaarticular’ cyst located in a right dorsolateral position of the intervertebral foramen at L3–L4 was diagnosed by magnetic resonance imaging. The cyst was removed through a modified laminectomy. The dog recovered quickly and returned to the owners 4 days after surgery with slight neurological symptoms. During the follow‐up examination 2 and 6 months later, the Setter showed normal gait and neurological examination.  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