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   18306篇
  免费   1955篇
  国内免费   574篇
耳鼻咽喉   141篇
儿科学   535篇
妇产科学   280篇
基础医学   1826篇
口腔科学   418篇
临床医学   1776篇
内科学   3765篇
皮肤病学   423篇
神经病学   1510篇
特种医学   348篇
外国民族医学   1篇
外科学   1551篇
综合类   2584篇
预防医学   815篇
眼科学   357篇
药学   2351篇
  26篇
中国医学   1669篇
肿瘤学   459篇
  2024年   121篇
  2023年   568篇
  2022年   1011篇
  2021年   1344篇
  2020年   1273篇
  2019年   1027篇
  2018年   919篇
  2017年   968篇
  2016年   879篇
  2015年   765篇
  2014年   1200篇
  2013年   1557篇
  2012年   982篇
  2011年   979篇
  2010年   750篇
  2009年   750篇
  2008年   730篇
  2007年   695篇
  2006年   639篇
  2005年   580篇
  2004年   447篇
  2003年   416篇
  2002年   339篇
  2001年   309篇
  2000年   257篇
  1999年   166篇
  1998年   164篇
  1997年   139篇
  1996年   127篇
  1995年   95篇
  1994年   96篇
  1993年   59篇
  1992年   62篇
  1991年   64篇
  1990年   53篇
  1989年   50篇
  1988年   31篇
  1987年   36篇
  1986年   25篇
  1985年   24篇
  1984年   28篇
  1983年   16篇
  1982年   23篇
  1981年   16篇
  1980年   14篇
  1979年   13篇
  1978年   14篇
  1976年   6篇
  1974年   2篇
  1972年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
凝血机制紊乱在SIRS发展中的作用   总被引:2,自引:0,他引:2  
凝血机制紊乱在全身炎症反应综合症(SIRS)发展、恶化过程中起重要作用.对SIRS时凝血系统紊乱的形成机制、在SIRS发生发展过程中的作用及其对病情危重程度的预测价值作一综述.  相似文献   
43.
本文应用磁性磷酸酶-抗碱性磷酸酶桥联酶标技术(APAAP),对27例原发性肾小球疾病患者外周血T淋巴细胞亚群进行观察。结果表明:本组病例表现为CD细胞升高,CD细胞减少,和CD/CD比值增加。提示原发性肾小球疾病可导致细胞免疫功能改变,T淋巴细胞亚群的变化,是肾组织损害的一个间接证据,可作为临床诊断一个有价值的参考指标。  相似文献   
44.
45.
Objective:To assess the sensitivity and the specifity of predicting idiopathic AF with P wave dura-tion and P wave dispersion. Methods: The maximum P wave duration and P wave dispersion in 36 patients with idio-pathic AF were measured and compared with those of sex-and age-matched healthy subjects. Results:The maxi-mum P wave duration and P wave dispersion were higher in patients with idiopathic Af than in control group. Themaximum P wave duration >110ms or P wave dispersion >40ms was used to differentiate patients from healthy  相似文献   
46.
目的回顾采用椎弓根钩和螺钉CD技术治疗特发性脊柱侧凸King型和型患者,分析选择性缩短融合节段的治疗效果。方法2000年3月~2003年1月,治疗58例特发性脊柱侧凸单胸弯患者,男17例,女41例,年龄12~18岁,平均14岁。其中King型40例,King型18例。胸弯Cobb角平均64°(50~83°),柔韧性62%;腰弯Cobb角平均37°(16~48°),柔韧性105%。腰弯腰骶角平均为17°(10~22°)。所有患者C7重力垂线均不同程度地偏离骶骨中线。采用椎弓根钩和螺钉CD技术矫形治疗,以中立椎为基础选择远端融合椎,所有远端融合节段均未超过中立椎。术后随访摄站立前后位和侧位X线片,观察各项指标的变化。结果患者均获随访1年8个月~3年2个月,平均2.4年,均未出现明显的躯干侧方移位和双肩不平衡。术后Cobb角平均丢失3.1°(-1~5°);最后随访时,胸弯矫正率68%;除2例C7重力垂线偏离骶骨中线1~2cm外,其余均通过骶骨中线;腰弯腰骶角减少至平均8°(2~13°),矫正率为53%;48例远端融合椎为非稳定椎者术后成为稳定椎。与Harrington远端融合椎选择原则相比,患者远端融合椎平均节省1.4个节段(1~2个节段)。结论采用三维节段性器械内固定系统治疗特发性单胸弯时,以中立椎为基础选择远端融合椎,可获得较好的临床效果。  相似文献   
47.
AIMS: Type 2 diabetes mellitus (DM) and coronary artery disease (CAD) are both associated with endothelial dysfunction and elevated oxidative and inflammatory state. We examined the effect of vitamin C on endothelial function and levels of soluble vascular cell adhesion molecule (sVCAM-1), interleukin-6 (IL-6) and tumour necrosis factor (TNF-alpha), in DM patients with or without CAD and in non-diabetic subjects. METHODS: Thirty-seven patients with DM + CAD, 17 patients with DM without CAD and 21 non-diabetic subjects were divided into groups receiving vitamin C 2 g/day or no anti-oxidant for 4 weeks. Forearm blood flow was determined using venous occlusion gauge-strain plethysmography. Forearm vasodilatory response to reactive hyperemia was considered as index of endothelium-dependent dilation. RESULTS: Baseline levels of IL-6 and TNF-alpha were significantly higher in patients with DM + CAD compared with patients with DM (P < 0.01) or non-diabetic subjects (P < 0.01). IL-6 and TNF-alpha levels were also higher in DM compared with non-diabetic subjects (P < 0.05). sVCAM-1 levels were lower in non-diabetic controls compared with DM + CAD (P < 0.05) or DM (P < 0.05). Reactive hyperaemia was higher in non-diabetic controls compared with DM + CAD (P < 0.001) or DM (P < 0.001). Vitamin C significantly increased reactive hyperaemia only in the DM + CAD group, while it had no effect on serum levels of sVCAM-1, TNF-alpha and IL-6 in any of the groups. CONCLUSIONS: Type 2 diabetes mellitus is associated with impaired endothelial function and increased levels of TNF-alpha, IL-6 and sVCAM-1, especially in patients with DM and CAD. Vitamin C significantly increased forearm vasodilatory response to reactive hyperaemia only in patients with combined DM and CAD.  相似文献   
48.
Inflammation and the Aging Process: Devil or Angel   总被引:1,自引:0,他引:1  
Inflammation is often viewed as a pathologic mechanism leading to tissue damage and interference with function, such as the process of chronic tissue scarring or fibrosis. However, it is important to note that inflammation is a crucial component of normal tissue repair as well as being fundamental to the body's defense against infection. Considering inflammation as a "causative agent in aging" belies the underlying mechanisms whereby the acute inflammatory response is necessary for survival, and efforts to reduce and control the inflammatory response leave the host susceptible to infectious agents and improper healing. Chronic inflammation inevitably has initiating mechanisms that include immune, autoimmune, and metabolic pathways, leading to the activation and presence of the host-protective response. It is more appropriate to target the underlying initiating conditions than the inflammatory process that ensues and treat the basic mechanisms of disease rather than interfere in a very important protective mechanism of the host.  相似文献   
49.
Background : Nonsteroidal anti–inflammatory drugs (NSAIDs) inhibit prostaglandin synthesis which may result in impaired platelet function. Because NSAIDs have different abilities to inhibit cyclo–oxygenases we compared the effect of intravenous ketoprofen, ketorolac and diclofenac on platelet function in volunteers. Methods : Ten healthy male volunteers were given ketoprofen 1.4 mg kg-1, ketorolac 0.4 mg kg-1 and diclofenac 1.1 mg kg-1 in saline i.v. on three different occasions, at more than one–week intervals, in a randomized double–blind crossover study. Platelet function was evaluated before (sample 0), 2 (sample 2) and 24 h (sample 3) after the beginning of the infusion. Results : Two of the volunteers had no secondary platelet aggregation in their aggregation curves before the experiment (sample 0, studied three times) and their results were excluded from the final analysis. Diclofenac inhibited adrenaline (0.9 μg–ml-1) induced platelet aggregation less (median maximal aggregation 22.5%) than ketoprofen (18.3%) and ketorolac (15.7%) (P<0.05) in sample 2. In the ketorolac group in sample 3 an impairment of adrenaline (0.9 ng ml-1) induced platelet aggregation was still seen (26.7%) (P<0.05) but not in the other groups. Diclofenac did not affect adenosine diphosphate (ADP) induced platelet aggregation. However, ketorolac caused an impairment in ADP (3 μM and 6 μM) induced platelet aggregation and ketoprofen in ADP (6 μM) induced platelet aggregation in sample 2. Bleeding time was prolonged (P<0.05) after ketoprofen and ketorolac (sample 2) but not after diclofenac. Platelet retention on glass beads was unaffected by the tested drugs. Conclusion : Ketoprofen, ketorolac and diclofenac caused a reversible platelet dysfunction. Diclofenac had the mildest effect, while platelet dysfunction was still seen 24 h after the beginning of ketorolac.  相似文献   
50.
Abstract Idiopathic Parkinson’s disease (IPD) patients have abnormal visual evoked potentials (VEPs) and pattern electroretinograms (PERGs), attributed to dopaminergic transmission deficiency in visual pathway, probably the retina. VEP abnormalities are not reported in multiple system atrophy (MSA). The aim of this study was to investigate and compare chromatic (Ch) red-green (R-G) and blue-yellow (B-Y), and luminance yellow-black (Y-Bk) PERGs in patients with MSA and IPD. We investigated 6 MSA patients (mean age: 62±7.4 years) not undergoing any pharmacological treatment, as well as 12 early IPD patients (mean age: 60.1±8.3 years) and 12 age-matched normal observers. ChPERGs were recorded monocularly in response to full-field equiluminant R-G, B-Y and Y-Bk horizontal gratings. In MSA only responses to R-G stimuli showed minimal insignificant changes (slight but not significant amplitude reduction without any significant latency delay); no significant abnormality was detected for B-Y and luminance Y-Bk stimuli. By contrast, in IPD all responses were reduced in amplitude and delayed in latency, above all for B-Y stimuli. Present data indicate that both chromatic and achromatic PERGs are virtually unaffected in MSA, whereas in early IPD they are clearly impaired, suggesting different pathogenic retinal mechanisms and a useful simple tool for distinguishing MSA from IPD.  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