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   67971篇
  免费   6357篇
  国内免费   4852篇
耳鼻咽喉   654篇
儿科学   709篇
妇产科学   623篇
基础医学   7977篇
口腔科学   1151篇
临床医学   9011篇
内科学   10042篇
皮肤病学   626篇
神经病学   3694篇
特种医学   2611篇
外国民族医学   34篇
外科学   7145篇
综合类   11583篇
现状与发展   16篇
一般理论   1篇
预防医学   4679篇
眼科学   1915篇
药学   7036篇
  76篇
中国医学   3529篇
肿瘤学   6068篇
  2025年   19篇
  2024年   847篇
  2023年   1448篇
  2022年   2836篇
  2021年   3520篇
  2020年   2693篇
  2019年   2236篇
  2018年   2342篇
  2017年   2091篇
  2016年   2018篇
  2015年   3143篇
  2014年   3792篇
  2013年   3237篇
  2012年   5086篇
  2011年   5635篇
  2010年   3647篇
  2009年   2691篇
  2008年   3395篇
  2007年   3533篇
  2006年   3432篇
  2005年   3545篇
  2004年   2267篇
  2003年   2132篇
  2002年   1769篇
  2001年   1415篇
  2000年   1586篇
  1999年   1615篇
  1998年   1079篇
  1997年   1010篇
  1996年   759篇
  1995年   707篇
  1994年   675篇
  1993年   394篇
  1992年   474篇
  1991年   426篇
  1990年   365篇
  1989年   313篇
  1988年   232篇
  1987年   227篇
  1986年   170篇
  1985年   114篇
  1984年   67篇
  1983年   59篇
  1982年   43篇
  1981年   31篇
  1980年   17篇
  1979年   24篇
  1978年   4篇
  1975年   4篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.

Purpose

To review the surgical techniques and mid-term results of mitral valve repair in children with moderate or severe mitral regurgitation (MR).

Methods

One hundred and seven children with moderate or severe MR, aged 19.6 ± 8.5 months, were enrolled in this study. The surgical techniques used for mitral valve repair varied according to the mitral valve morphology, and included annuloplasty, annuloplasty ring, cleft closure, reconstruction of the posterior leaflet, etc. The concomitant cardiac anomalies were treated simultaneously. The results of repair were evaluated by transesophageal echocardiography performed during the operation and by serial transthoracic echocardiography performed during the follow-up.

Results

One hundred and six cases had no more than mild regurgitation intraoperatively, whereas only one case had moderate regurgitation. This patient underwent redo repair immediately, and the subsequent regurgitation was trivial. The in-hospital mortality rate was 0.9 % (1/107). The average follow-up was 46.5 ± 8.2 months. One patient died of heart failure 10 months postoperatively. The freedom from moderate or severe regurgitation after mitral valve repair was 92.3 ± 3.3 %.

Conclusion

Pediatric patients with moderate or severe MR require early surgical treatment. The early and mid-term results of mitral valve repair in pediatric patients were satisfactory.  相似文献   
62.
目的探讨新型咽鼓管吹张法对儿童分泌性中耳炎的治疗效果。方法将90例分泌性中耳炎患儿按照随机数字表分为对照组和观察组各45例。观察组采用新型咽鼓管吹张法治疗,对照组采用传统的波氏球咽鼓管吹张法治疗,观察记录治疗3个月后两组患儿声阻抗检测变化及患儿的舒适度。结果治疗3个月后两组患儿的声阻抗检测结果及舒适度比较,差异有统计学意义(P0.05,P0.01)。结论新型咽鼓管吹张法能提高患儿操作时的舒适度,增加患儿治疗的信心,提高疾病治疗效果。  相似文献   
63.
Objective To identify novel biomarker for diabetic nephropathy (DN) by urinary proteomic methods, and to detect the expression of E-cadherin in urine and renal tissue of patients with DN. Methods Urine samples were collected from 12 cases of type 1 diabetic nephropathy patients (T1DN), 12 cases of type 2 diabetic nephropathy patients (T2DN), 12 cases of nephritic syndrome patients (NS), and 12 cases of healthy Controls. Comparative proteomic approach of two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) were employed to identify DN-related biomarker in urine samples. The differential expression of the identified biomarker in urine samples and renal biopsy specimens were detected by Western blotting and immunohistochemistry method. Results E-cadherin was identified by 2DE/MS, which was significantly up-regulated in T1DN and T2DN groups (all P< 0.01). Western blotting confirmed the expression of E-cadherin was significantly higher in T1DN and T2DN groups than in NS and Control groups (all P<0.01). Immunohistochemical stain showed E-cadherin was mainly expressed in the membrane and cytoplasm of renal tubular epithelial cell, and its expression was markedly decreased in DN kidneys compared with healthy Controls (P<0.05). Conclusions E-cadherin is identified as a novel DN-related biomarker, which is specifically increased in urine of DN patients.  相似文献   
64.
Photoacoustic tomography (PAT) is an emerging non-invasive imaging technique with great potential for a wide range of biomedical imaging applications. However, the conventional PAT reconstruction algorithms often provide distorted images with strong artifacts in cases when the signals are collected from few measurements or over an aperture that does not enclose the object. In this work, we present a total-variation-minimization (TVM) enhanced iterative reconstruction algorithm that can provide excellent photoacoustic image reconstruction from few-detector and limited-angle data. The enhancement is confirmed and evaluated using several phantom experiments.  相似文献   
65.
Dear Editor,
I am Dr. Hui-Rong Chen, from the Department of Urology in Shanghai First People's Hospital at Shanghai Jiao Tong UnNersity, Shanghai, China. Premature ejaculation (PE) is a common sexual dysfunction, affecting approximately 20%-30% of sexually active men. According to intravaginal ejaculatory latency time (IELT) of l min, the incidence is approximately 1%-3%.1 PE is significantly associated with many personal and negative consequences, such as distress, frustration, and avoidance of sexual intimacy due to the inability of successful delayed ejaculation, α1-adrenergic blockers were effective in delaying ejaculation in approximately 50%-67% of the cases.2,3 Recently, abnormal ejaculation, an adverse infrequent side effect associated with the use of α1A-adrenergic blockers such as silodosin or tamsulosin, has drawn significant attention. Clinical studies suggested that this represents a relative anejaculation rather than a retrograde ejaculation. We present here the study to investigate the role of urethral pressure profile (UPP) on treating PE by tamsulosin.  相似文献   
66.
The blood-testis barrier (BTB) is found between adjacent Sertoli cells in the testis where it creates a unique microenvironment for the development and maturation of meiotic and postmeiotic germ cells in seminiferous tubes. It is a compound proteinous structure, composed of several types of cell junctions including tight junctions (TJs), adhesion junctions and gap junctions (GJs). Some of the junctional proteins function as structural proteins of BTB and some have regulatory roles. The deletion or functional silencing of genes encoding these proteins may disrupt the BTB, which may cause immunological or other damages to meiotic and postmeiotic cells and ultimately lead to spermatogenic arrest and infertility. In this review, we will summarize the findings on the BTB structure and function from genetically-modified mouse models and discuss the future perspectives.  相似文献   
67.
乙肝病毒标志物定量检测与肝脏损害的相关性研究   总被引:1,自引:0,他引:1  
目的:探讨乙肝病毒标志物定量检测与肝脏损害的关系。方法:采用人院时第一份血清,应用时间分辨免疫荧光分析法(TRIFA)测定696例乙肝患者病毒标志物的含量,同步监测肝功能。结果:HBeAb与ALT呈负相关(r=-0.346,P〈0.05),HBeAg与TBIL呈负相关(r=-0.230,P〈0.05),而乙肝病毒标志物定量与AST、PAB、ALB、PT无关。结论:不能完全以乙肝病毒标志物的定量来判断患者肝功能的好坏。  相似文献   
68.
目的:观察能明显促进禽类等动物的生长发育,改善肉质的新型饲料添加剂N,O-羧甲基壳聚糖对昆明种小白鼠精子畸形的影响,分析其应用在畜牧生产中的安全性。方法:实验于2005-06-22/2005-08-06于南京农业大学动物医学院药理组实验室完成。挑选体质量25~28g的小鼠50只,以随机数字表法分为生理盐水组、环磷酰胺组、N,O-羧甲基壳聚糖(南京龙源天然多酚合成厂提供,商品名为毕罗喜,质量浓度为105g/kg)2,4,8g/kg剂量组,每组10只。N,O-羧甲基壳聚糖2,4,8g/kg剂量组分别给予相应剂量的N,O-羧甲基壳聚糖,溶于1mL生理盐水,2,4g/kg剂量1次灌服,8g/kg剂量分2次灌服,每次间隔约3h;生理盐水组给予生理盐水1mL;环磷酰胺组给予环磷酰胺0.04g/kg,溶于1mL生理盐水。给药前禁食10h,不禁水。连续灌胃5d,给药后30d麻醉下处死,取两侧附睾按Wyrobek方法涂片,观察小白鼠精子畸形状况。评估标准参照农业部兽药评审委员会办公室编写的兽药试验技术规范汇编(2001年)。评估内容参照沈建忠主编的动物毒理学(中国农业出版社,2002年),包括各种畸形的精子形态:不定形、胖头、香蕉头、无钩、双头(多头)和双尾(多尾)等,及其分类计数。每组随机选取5只小鼠,计算总畸形率。精子畸形率(%)=畸形精子总数/检查精子总数×100。结果:最终25只小鼠进入结果分析,每组5只。①环磷酰胺组的精子畸形率远高于生理盐水组和N,O-羧甲基壳聚糖2,4,8g/kg剂量组(6.10%,2.48%,2.46%,2.64%,2.78%,P<0.01);N,O-羧甲基壳聚糖2,4,8g/kg剂量组与生理盐水组比较,差异无显著性意义(P>0.05),且各剂量组之间差异也没有显著性意义(P>0.05)。②各组精子畸形主要表现为头部或尾部异常。以无定形和胖头居多,占35.48%(292/823)和29.28%(241/823);其次是无钩形及香焦形多见,占19.68%(162/823)和13.49%(111/823);偶尔可见双头双尾形,只占2.07%。结论:N,O-羧甲基壳聚糖精子畸形试验结果呈阴性,说明其对雄性生殖细胞没有明显的遗传毒性。  相似文献   
69.
放松训练配合理疗对高正常血压患者血压的影响   总被引:5,自引:0,他引:5  
目的 随着人们对高血压病的深入研究 ,越来越认识到血压增高对人体的危害。血压越高 ,持续时间越长 ,心、脑、肾等脏器损害出现的时间越早 ,程度越重。因此 ,早期发现和治疗高血压病日渐重要。本文通过对住院疗养的高正常血压患者 30例 ,经放松训练、松脂粉矿泉浸浴、高压电子的非药物治疗后 ,患者收缩压及舒张压均有下降 ,(P<0 .0 1)。为预防高血压病的发生 ,控制血压水平提供一条简便、易行的治疗方法。  相似文献   
70.
Rh2 is a rare ginsenoside and there are few reports of its effect on cognition compared with other similar molecules. This study aimed to establish the impact of Rh2 treatment on improving scopolamine (Scop)‐induced memory deficits in mice and illuminate the underlying mechanisms. First, memory‐related behavior was evaluated using two approaches: object location recognition (OLR), based on spontaneous activity, and a Morris water maze (MWM) task, based on an aversive stimulus. Our results suggested that Rh2 treatment effectively increased the discrimination index of the mice in the OLR test. In addition, Rh2 elevated the crossing numbers and decreased the escape latency during the MWM task. Moreover, Rh2 markedly upregulated the phosphorylation of the extracellular signal‐regulated kinase (ERK)‐cAMP response element binding (CREB)‐brain derived neurotrophic factor (BDNF) pathway in the hippocampus. Meanwhile, the administration of Rh2 significantly promoted the cholinergic system and dramatically suppressed oxidative stress in the hippocampus. Taken together, Rh2 exhibited neuroprotective effects against Scop‐induced memory dysfunction in mice. Rh2 activity might be ascribed to several underlying mechanisms, including its effects on modulating the cholinergic transmission, inhibiting oxidative stress and activating the ERK‐CREB‐BDNF signaling pathway. Consequently, the ginsenoside Rh2 might serve as a promising candidate compound for Alzheimer's disease.  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