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   38723篇
  免费   2090篇
  国内免费   140篇
耳鼻咽喉   387篇
儿科学   936篇
妇产科学   758篇
基础医学   5041篇
口腔科学   1732篇
临床医学   2733篇
内科学   9825篇
皮肤病学   838篇
神经病学   3380篇
特种医学   796篇
外科学   5653篇
综合类   320篇
一般理论   14篇
预防医学   2887篇
眼科学   1088篇
药学   2090篇
中国医学   158篇
肿瘤学   2317篇
  2024年   29篇
  2023年   290篇
  2022年   602篇
  2021年   1320篇
  2020年   712篇
  2019年   1069篇
  2018年   1312篇
  2017年   836篇
  2016年   853篇
  2015年   1131篇
  2014年   1509篇
  2013年   1889篇
  2012年   3082篇
  2011年   3184篇
  2010年   1753篇
  2009年   1609篇
  2008年   2743篇
  2007年   2819篇
  2006年   2597篇
  2005年   2401篇
  2004年   2051篇
  2003年   1848篇
  2002年   1754篇
  2001年   277篇
  2000年   198篇
  1999年   273篇
  1998年   322篇
  1997年   245篇
  1996年   197篇
  1995年   181篇
  1994年   180篇
  1993年   142篇
  1992年   124篇
  1991年   109篇
  1990年   90篇
  1989年   86篇
  1988年   77篇
  1987年   73篇
  1986年   67篇
  1985年   64篇
  1984年   84篇
  1983年   70篇
  1982年   77篇
  1981年   87篇
  1980年   44篇
  1979年   43篇
  1978年   59篇
  1977年   53篇
  1976年   46篇
  1973年   37篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
81.
82.
INTRODUCTION : In patients with common bile duct (CBD) stones, the diameter of the CBD is usually dilated. After surgery, the behavior of CBD diameter is not clearly known. OBJECTIVE : To determine at a late follow-up the width of CBD before and after choledochostomy for CBD stones. MATERIAL AND METHODS : In this prospective study, 39 patients with gallstones and CBD stones were included. They were 30 women and 9 men with a mean age of 52.6 years. In all ultrasound, determination of the CBD caliber before and 12 years after surgery was performed. RESULTS : The mean value of the inner diameter of the CBD before surgery was 11.6 and 12.3 mm in patients below or above 60 years, respectively. Measurement 12 years after surgery showed a mean decrease of nearly 50% of preoperative values, which was highly significant (p < 0.0001). However, either below or above 60 years, only 75% of the patients showed this decrease, whereas 25% remained unchanged. CONCLUSION : The dilated preoperative CBD returns to normal or near normal values in 3/4 of the patients after surgical exploration of the CBD and extraction of the stones.  相似文献   
83.
84.
K B Saunders  S S Fernando  H R Dalton    A Joseph 《Thorax》1994,49(7):725-727
A 37 year old patient with chronic active hepatitis progressing to cirrhosis presented with increasing breathlessness and was found to be hypoxic with finger clubbing. A progressive exercise study with measurement of oxygen saturation (SaO2) showed abnormally high ventilation and desaturation to 81% at 100 W. Serial studies over nearly two years showed, first, deterioration, then improvement with lower ventilation and higher saturation levels at all work loads. This could not be correlated with any change in treatment with azathioprine, prednisolone, or propranolol.  相似文献   
85.
We studied 12 non-demented PD patients in on state before and 3 months after posteroventral pallidotomy (PVP), in order to evaluate the effects of surgery upon an unconstrained, multijoint skilled movement as well as a single joint, repetitive, ballistic movement. A Selspot II System was used for three-dimensional data acquisition, processing and reconstruction of limb trajectories. Specific wrist kinematic features of spatial accuracy (linearity and planarity), temporal attributes (acceleration and velocity), spatiotemporal relationships (velocity-curvature coupling), and joint kinematic variables (relationships between wrist and elbow velocities and relative arm angle amplitudes) for each cycle of movement were graphically and numerically analysed. QMC was applied to single joint, repetitive, ballistic movements. QMC significantly improved after PVP (P < 0.0006). However, wrist as well as joint kinematic variables of the gestural movements failed to change significantly after PVP. The lack of improvement of the kinematic abnormalities of the gestural movement in PD patients would indicate that they are unrelated to the basic motor deficit; most likely they are the result of a disruption of a complex of sensorimotor integration processes due to abnormal parieto-frontal basal ganglia interaction.  相似文献   
86.
The effects were studied of a toxin (Bainh) isolated from the secretion of the Caribbean sea anemone Bunodosoma granulifera on electrical and mechanical activities of rat ventricular muscle. The effects on the ionic currents of single rat and dog ventricular cardiomyocytes were studied using the whole-cell recording patch-clamp technique. In the concentration range from 1 to 10 mg/ml, Bainh increased the force of contraction and induced an increase in action potential duration of ventricular multicellular preparations. In single cardiomyocytes, at concentrations up to 10 mg/ml Bainh showed no significant effects on the sodium current. However, at 0.5–1 mg/ml it increased the L-type Ca current (ICaL) by 25–50%. This increase in ICaL was not voltage dependent and was reversible after washout. The transient outward current was not significantly affected by Bainh (1–10 mg/ml). In this concentration range, Bainh markedly (≈75%) increased the inward-going rectifier current, IK1. This effect that was not voltage dependent and was fully reversible upon returning to control solution. It is suggested that these effects on ionic currents could explain the positive inotropic action of Bainh on cardiac multicellular preparations.  相似文献   
87.
In this study, we report that 5-HT(1A) receptors are already present in fractions of axonal growth cones, from the normal rat fetal brain (E-17). Also, in utero undernourished (UN) rat pups at birth show a noteworthy enhancement in the B(max) of [3H]5-hydroxytryptamine (5-HT) and [3H]8-hydroxy-(2-N,N-dipropilamin)-tetralin (([3H])8-OH-DPAT), in the brainstem and cerebral cortex up to the second week after birth. Afterwards, there is a significant decrease in the binding of these ligands. [125I]Cyanopindolo binding in the cerebral cortex only showed a decrease in the same period. An elevation of brain serotonin in both regions was also present. These findings together, suggest that the mechanisms of regulation of serotonergic receptors' expression during the period studied, may not depend on the amount of neurotransmitter in the synaptic cleft, because in the early UN brain it would be expected only a lower receptor's density due to the chronic serotonin increase. On this basis, we propose that developmental activation of brain serotonin biosynthesis observed in early UN animals may disrupt the mechanism regulating the expression of 5-HT receptors during development.  相似文献   
88.
The aim of this study was to evaluate the rate of alcohol recidivism after orthotopic liver transplantation (OLT) for alcoholic liver disease (ALD) and its influence on the allograft and patient survival, as well as the development of comorbidities and de novo cancers. The study was performed on 54 subjects previously analyzed and transplanted in our center for ALD, whose follow-up was prolonged to a mean of 99.2 (SD 31.7) months (range, 14-155). Medical records were reviewed, and data on alcohol consumption, therapeutic compliance, graft evolution, rejection, infections, comorbidities, rates of de novo malignancies and other clinical events, and survival were collected. Comparisons between groups were performed by the Fisher's exact test, and survival was assessed by the Kaplan-Meier method. Survival curves were compared using the Mantel-Cox statistic. The risk of death resulting from alcohol recidivism was analyzed with a Cox proportional hazards model. Fourteen patients who underwent transplantation for ALD (25.9%) returned to alcohol use between 5.0 and 86.9 months after OLT (median, 47.5). There was no significant association between the presence or absence of alcohol recidivism and the occurrence of graft rejection, infections, associated comorbidities after OLT, or compliance. The 5- and 10-year survival rates for patients with alcohol recidivism were 92.9% and 45.1%, respectively, compared with 92.4% and 85.5%, respectively, for patients without alcohol recidivism. These figures show significantly lower survival rates in recidivistic patients after 10 years (P < 0.01, Mantel-Cox). The fact that patients who resumed alcohol consumption have a worse 10-year survival rate might be attributed to a higher frequency of deaths, primarily from cancer and cardiovascular events.  相似文献   
89.
90.
Older age is not considered a contraindication for liver transplantation, but age-related morbidity may be a cause of mortality. Survival and the incidence of the main post-transplant complications were assessed in 111 adult liver transplant recipients. They were divided in two groups according to their age (patients younger than 60 years, n=54; patients older than 60 years, n=57) and both groups were compared. Older patients were more frequently transplanted for hepatitis C (p= 0.03) and hepatocellular carcinoma (p= 0.05) and their liver disease was less advanced (Child-Pugh and MELD scores were significantly lower; p=0.004 and p=0.05, respectively). After transplantation, older patients had a significantly lower survival (p=0.02). Higher age was independently associated with mortality (hazard ratio for each 10-year increase: 2.1; 95% confidence interval: 1.1- 4.0; p=0.02). The incidence of de novo neoplasia and nonskin neoplasia were higher in older patients (p=0.02 and p =0.007, respectively). Malignancy was the cause of death in one patient younger than 60 years and in 12 patients older than 60 years (p =0.002). In multivariate analysis, a higher age and smoking were independently associated with a higher risk of dying of de novo neoplasia. In conclusion, older liver transplant recipients have a significantly lower survival than younger patients. Malignancy is responsible for this decreased survival.  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