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   95199篇
  免费   9379篇
  国内免费   3048篇
耳鼻咽喉   594篇
儿科学   1508篇
妇产科学   1193篇
基础医学   10219篇
口腔科学   2315篇
临床医学   11841篇
内科学   19733篇
皮肤病学   1082篇
神经病学   9020篇
特种医学   1897篇
外国民族医学   1篇
外科学   9228篇
综合类   12386篇
现状与发展   13篇
一般理论   3篇
预防医学   6816篇
眼科学   956篇
药学   10267篇
  61篇
中国医学   6150篇
肿瘤学   2343篇
  2024年   390篇
  2023年   1986篇
  2022年   3339篇
  2021年   4754篇
  2020年   4502篇
  2019年   4057篇
  2018年   3771篇
  2017年   4193篇
  2016年   4497篇
  2015年   4415篇
  2014年   6552篇
  2013年   8091篇
  2012年   5501篇
  2011年   6199篇
  2010年   4798篇
  2009年   4696篇
  2008年   4591篇
  2007年   4309篇
  2006年   3857篇
  2005年   3150篇
  2004年   2730篇
  2003年   2352篇
  2002年   1965篇
  2001年   1699篇
  2000年   1428篇
  1999年   1119篇
  1998年   981篇
  1997年   938篇
  1996年   841篇
  1995年   708篇
  1994年   643篇
  1993年   535篇
  1992年   497篇
  1991年   423篇
  1990年   382篇
  1989年   357篇
  1988年   289篇
  1987年   245篇
  1986年   244篇
  1985年   332篇
  1984年   245篇
  1983年   166篇
  1982年   184篇
  1981年   177篇
  1980年   120篇
  1979年   98篇
  1978年   86篇
  1977年   61篇
  1976年   57篇
  1975年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
目的:从血清生化,病毒学,肝纤维化指标以及肝脏组织病理学改变的角度分析拉米夫定(LMD)治疗慢性乙型肝炎的疗效.方法:慢性乙型肝炎患者21例,给予口服LMD100 mg/d,连用1 a,动态观察服药0,24和48 wk肝功能、乙肝五项、HBV-DNA定量、血清肝纤维化指标透明质酸(HA)、层黏蛋白(LN)、Ⅲ型前胶原(PⅢP)和Ⅳ型胶原(ⅣC)的变化,通过肝组织穿刺活检,观察用药前后肝脏组织病理学的改变.结果:LMD治疗48 wk,可显著抑制HBV-DNA(copy/L)复制(6.13×109±4.03×105 vs 9.01×105±4.89×103,P<0.01),使大多数患者肝功能(nkat/L,ALT:1697±907 vs550±503;AST:1787±717 vs 498±430)恢复正常(P<0.01),显著降低血清肝纤维化指标水平(P<0.01).减轻肝细胞坏死,汇管区炎细胞浸润及纤维化.结论:LMD是治疗慢性乙型肝炎的一种较为切实有效的措施.  相似文献   
42.
The emergence of a near-haploid clone of cells in blast phase chronic myelogenous leukemia is an unusual event. We report such a case and review eight other cases described in the English literature. The significance of the substantial loss of genetic material is discussed as is the phenotypic and genotypic heterogeneity observed in this group of patients.  相似文献   
43.
Background Oxidative stress and increased inflammation have been reported to be increased in subjects with diabetes and to be involved in the pathogenesis of cardiovascular complications after myocardial infarction (MI). It is well recognized that red wine has antioxidant and anti‐inflammatory activities. We examined the effects of moderate red wine intake on echocardiographic parameters of functional cardiac outcome in addition to inflammatory cytokines and nitrotyrosine (oxidative stress marker), in subjects with diabetes after a first uncomplicated MI. Methods One hundred and fifteen subjects with diabetes who had sustained a first non‐fatal MI were randomized to receive a moderate daily amount of red wine (intervention group) or not (control group). Echocardiographic parameters of ventricular dys‐synchrony, circulating levels of nitrotyrosine, tumour necrosis factor‐α (TNF‐α), interleukin‐6 (IL‐6), interleukin‐18 (IL‐18) and C‐reactive protein (CRP) were investigated at baseline and 12 months after randomization. Results After 1 year of diet intervention, concentrations of nitrotyrosine (P < 0.01), CRP (P < 0.01), TNF‐α (P < 0.01), IL‐6 (P < 0.01) and IL‐18 (P < 0.01) were increased in the control group compared with the intervention group. In addition, myocardial performance index (P < 0.02) was higher, and transmitral Doppler flow (P < 0.05), pulmonary venous flow analysis (P < 0.02) and ejection fraction (P < 0.05) were lower in the control group, indicating ventricular dys‐synchrony. The concentrations of nitrotyrosine, CRP, TNF‐α and IL‐6 were related to echocardiographic parameters of ventricular dys‐synchrony. Conclusions In subjects with diabetes, red wine consumption, taken with meals, significantly reduces oxidative stress and pro‐inflammatory cytokines as well as improving cardiac function after MI. Moderate red wine intake with meals may have a beneficial effect in the prevention of cardiovascular complications after MI in subjects with diabetes.  相似文献   
44.
Irritability is often a problem for patients with Post-Traumatic Stress Disorder (PTSD). We describe two cases that illustrate the use of lithium in the treatment of veterans with PTSD who complained of serious problems with irritability or angry outbursts. These cases are discussed in the context of evidence that lithium may be useful in other patients with disorders of impulse control. The evidence linking disorders of anger and impulse control to a dysregulation in neurotransmitter regulation, particularly in serotonergic pathways, supports a psychopharmacologic approach to treatment. These findings should lead to further study of the role of lithium in the treatment of this symptom complex in patients with PTSD.  相似文献   
45.
The synthesis of nerve growth factor (NGF) by the hippocampus raises the possibility that NGF may play a role in the regulation of the hypothalamic-pituitary-adrenal axis (HPAA). Subchronic cold stress has been shown to activate the HPAA in a mild noninvasive manner, to stimulate serum glucocorticoid levels, and to perturb NGF binding in hippocampus and basal forebrain. One or repeated episodes of cold stress increased NGF mRNA levels in the hippocampus and p75NGFR mRNA levels in the basal forebrain. These changes were not due to elevated serum glucocorticoid levels since treatment with exogenous corticosterone had no effect on NGF and p75NGFR mRNA levels. Adrenalectomy did not prevent the stress induced increases in NGF and p75NGFR mRNA. © 1993 Wiley-Liss, Inc.  相似文献   
46.
47.
通过42例重型肺心病、7例轻型肺心病、16例肺心病伴发冠心病患者和30例正常人在静息状态下的左右心脏射血分数及其临床资料的分析表明,重型肺心病患者在病情的急性发作期,存在有不同程度的左心功能不全,而轻型肺心病患者则无左心功能不全的表现。表明慢性肺心病仅在病程晚期,才由以右心为主的疾病发展成为全心病。本文还对重型肺心病与肺心病伴发冠心病患者的左心功能进行比较,结果表明,肺心病伴发冠心病患者左室功能受损程度更为明显,双重病因导致的左室功能减退,常造成心肌更严重的损害而且不容易恢复。  相似文献   
48.
慢性硬膜下血肿及其发病机制探讨:150例临床分析   总被引:1,自引:0,他引:1  
岳树元  马喜 《天津医药》1993,21(4):212-215
  相似文献   
49.
硝基胍的毒性研究   总被引:2,自引:1,他引:1  
目的对硝基胍的毒性进行研究,为制订卫生标准提供依据.方法包括急性毒性试验、蓄积毒性试验及亚慢性毒性试验.结果硝基胍大鼠经口LD50为8 066 mg/kg,小鼠经口LD50为10 044 mg/kg,蓄积系数大于5.3.亚慢性毒性试验中,高剂量组雄性大鼠在染毒第3周和第8周,体重有明显的负增长(P<0.05);高剂量组雄性大鼠睾丸脏器系数明显高于对照组(P<0.05);红细胞免疫功能测定结果显示,中、高剂量组大鼠红细胞受体花环率分别为10.00±2.37和7.50±2.66,明显低于对照组(P<0.05,P<0.01).其余各项指标未见明显改变.结论硝基胍属于微毒级毒物,轻度蓄积,亚慢性毒性试验对动物有一定的影响.  相似文献   
50.
Abstract Several methods have been used to predict successful weaning and extubation among chronic obstructive pulmonary disease (COPD) patients. The objective of this study is to determine whether carbon dioxide recruitment threshold (PCO2RT) can be used as adjunct to conventional weaning parameters to predict early weaning and successful extubation. Twelve COPD patients who were ready to be extubated based on conventional weaning parameters were divided into group A ( n = 7) and group B ( n = 5). Group A were those patients with better weaning parameters and hence a higher probability of successful extubation as compared to group B. Carbon dioxide apnoeic threshold (PCO2AT) was obtained by hyperventilating the patient using an increment of two breaths per min until apnoea occurs. At this point, the PCO2AT or the PaCO2 during said apnoeic period was recorded. A dead space of 150 cc is then added to the circuit until the patient starts to breathe as evidenced by the sensitivity trigger indicator. The PCO2 obtained at this period is termed PCO2RT. After weaning for 30 min on a T-tube, another arterial blood gas is determined and this is called the PCO2SB or the CO2 level after 30 min on spontaneous breathing. If the PCO2SB-PCO2RT difference is high with a sensitivity of 85.71% and specificity of 100% vs sensitivity of 57.14% and specificity of 60% using the conventional weaning parameters. Thus an increase in PCO2SB at 30 min T-tube is indicative of impending respiratory pump failure and that other causes of failure to wean must be investigated.  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