全文获取类型
收费全文 | 222444篇 |
免费 | 17720篇 |
国内免费 | 7046篇 |
专业分类
耳鼻咽喉 | 1285篇 |
儿科学 | 7752篇 |
妇产科学 | 1604篇 |
基础医学 | 19919篇 |
口腔科学 | 3709篇 |
临床医学 | 23795篇 |
内科学 | 56371篇 |
皮肤病学 | 2777篇 |
神经病学 | 26320篇 |
特种医学 | 6358篇 |
外国民族医学 | 4篇 |
外科学 | 16972篇 |
综合类 | 30112篇 |
现状与发展 | 31篇 |
一般理论 | 9篇 |
预防医学 | 18414篇 |
眼科学 | 2440篇 |
药学 | 15260篇 |
191篇 | |
中国医学 | 10072篇 |
肿瘤学 | 3815篇 |
出版年
2024年 | 524篇 |
2023年 | 4458篇 |
2022年 | 8394篇 |
2021年 | 12192篇 |
2020年 | 11803篇 |
2019年 | 8417篇 |
2018年 | 8290篇 |
2017年 | 8234篇 |
2016年 | 8549篇 |
2015年 | 8254篇 |
2014年 | 15596篇 |
2013年 | 17067篇 |
2012年 | 12882篇 |
2011年 | 13948篇 |
2010年 | 10967篇 |
2009年 | 10506篇 |
2008年 | 10559篇 |
2007年 | 10169篇 |
2006年 | 9064篇 |
2005年 | 7502篇 |
2004年 | 6389篇 |
2003年 | 5510篇 |
2002年 | 4607篇 |
2001年 | 3998篇 |
2000年 | 3364篇 |
1999年 | 2861篇 |
1998年 | 2718篇 |
1997年 | 2394篇 |
1996年 | 2140篇 |
1995年 | 1932篇 |
1994年 | 1781篇 |
1993年 | 1520篇 |
1992年 | 1461篇 |
1991年 | 1282篇 |
1990年 | 1012篇 |
1989年 | 865篇 |
1988年 | 809篇 |
1987年 | 742篇 |
1986年 | 639篇 |
1985年 | 740篇 |
1984年 | 622篇 |
1983年 | 381篇 |
1982年 | 448篇 |
1981年 | 379篇 |
1980年 | 284篇 |
1979年 | 247篇 |
1978年 | 186篇 |
1977年 | 164篇 |
1976年 | 136篇 |
1975年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
肝脏螺旋CT动态增强扫描时肝动脉期肝实质一过性异常强化的研究 总被引:26,自引:1,他引:25
目的 研究肝脏螺旋CT动态增强扫描时肝动脉期肝实质一过性异常强化 (transienthepaticabnormalenhancement,THAE)的表现特征 ,探讨其产生原因及临床意义。方法 1999年 1月至2 0 0 1年 9月 92 6例患者因各种原因接受了肝脏或上腹部螺旋CT扫描。CT扫描常规先作全肝或上腹部螺旋CT平扫 ;注射对比剂开始后 2 5~ 3 0s行肝动脉期扫描 ,65~ 70s行门静脉期扫描 ;对部分病例还行病灶局部延迟扫描 ,延迟时间为 3、5及 10~ 15min。肝动脉期共检出 82例 (男 72例 ,女 10例 ;年龄 2 6~ 78岁 )具有THAE ,着重对其在平扫和增强各期图像上的表现、与肝内或肝外病灶的关系以及门静脉系统情况做详细观察和记录。结果 82例 (8 9% )共有 12 2处肝动脉期THAE ,其中 110处(90 2 % )平扫未显示THAE区域密度异常 ,12处 (9 8% )呈稍低密度 ;所有 12 2处THAE在肝动脉期都为均匀的高密度影 ;在门静脉期 ,10 9处 (89 3 % )转为等密度而不能分辨 ,余 13处 (10 7% )为均匀稍高密度影 (其中 10处作了延迟扫描 ,均转为等密度 )。 83处 (68 0 % )THAE呈边缘光滑的楔形或扇形 ,2 9处呈不规则形 (2 3 8% ) ,余为其他形状。THAE紧贴肝内肿瘤或其他病灶的有 46处 (3 7 7% ) ,邻近肝外肿瘤或其他病灶 2 0处 (16 4% ) ,余 5 6处 (45 相似文献
992.
Ullrich Wüllner Claudia M. Testa Maria Vincenza Catania Anne B. Young John B. Penney Jr. 《Brain research》1994,645(1-2)
We examined NMDA-sensitive [3H]glutamate, [3H]AMPA, [3H]kainate and metabotropic-sensitive [3H]glutamate binding sites in neostriatum and substantia nigra pars reticulata (SNr) in rats after unilateral 6-hydroxydopamine lesions of the medial forebrain bundle. One week after the lesion, NMDA, AMPA, kainate and metabotropic receptors were decreased in the ipsilateral neostriatum, whereas at three months NMDA receptors were increased while AMPA, kainate and metabotropic receptors were not changed. In the SNr at one week, only AMPA and metabotropic receptors were significantly decreased whereas three months after the lesion NMDA, AMPA and kainate binding sites were decreased. The early decrease of excitatory amino acid receptors in the striatum is likely to reflect degeneration of dopaminergic fibers, suggesting that specific subpopulations of excitatory amino acid binding sites are located on dopaminergic terminals. 相似文献
993.
Diabetic patients are at increased risk of cardiovascular disease, particularly when proteinuria is present. Lipoprotein(a)[Lp(a)] levels were assessed in 37 patients with insulin dependent (IDDM) and in 75 patients with non-insulin dependent (NIDDM) diabetes who showed varying degrees of proteinuria and glycaemic control. Median Lp(a) in 112 diabetic patients was significantly greater than in 116 healthy controls (113 vs 48 mg/L; p <0.01). 86 of the patients had first morning urine albumin concentration < 30 mg/L (normoalbuminuria = NA), 16 patients 30–200 mg/L (microalbuminuria = MA) and ten patients < 200 mg/L (albuminuria = ALB). There was no significant difference in median Lp(a) concentration between the three groups (NA = 108, MA = 163, ALB = 98 mg/L; p > 0.5). No significant difference in median Lp(a) concentration was found between patients with IDDM, NIDDM treated with insulin, or NIDDM treated with oral agents and/or diet (120, 98, 115 mg/L respectively; p > 0.7). When the 86 NA patients were divided on the basis of median fructosamine concentration (357 umol/L), no significant difference was found in median Lp(a) levels between those grouped below or above this median (98 mg/L vs 118 mg/L; p < 0.5). Across all diabetics studied there was no significant correlation present between Lp(a) and urinary protein or glycaemic control. These cross-sectional results suggest that median Lp(a) concentration is increased in both IDDM and NIDDM patients, but this increase is not related to the degree of proteinuria or short-term glycaemic control. 相似文献
994.
We investigated the distribution of prion protein (PrP) in 14 German patients with sporadic Creutzfeldt-Jakob disease (CJD) and compared it with that observed in Japanese patients. Immunohistochemical study revealed diffuse gray matter stainings including synaptic structures in all cases. In addition, 4 patients showed plaque-type deposition which was very rarely observed among sporadic Japanese patients without known mutation of the PrP gene but with valine at codon 129. A higher incidence of PrP plaques in German sporadic CJD may be related to the racial difference in the PrP gene. 相似文献
995.
用蝮蛇抗栓酶对7例急性心肌梗塞患者进行早期治疗,收到显著的效果.心绞痛消失时间1天~3天,平均1.5天.心电图ST段复位到基线时间1天~16天,平均10.2天.治疗后血液粘稠度下降. 相似文献
996.
在耳鼻咽喉科手术中应用颈外动脉栓塞法10例,形成栓塞组,并把单纯颈外动脉结扎10例作为对照组。结果表明:栓塞组较对照组术中出血量显著减少,有利于病灶彻底清除,因而有提高治愈率减少复发率的作用。掌握栓塞位置、栓塞剂用量和注射速度是防止并发症的关键。 相似文献
997.
Wilson's disease tremor is associated with magnetic resonance imaging lesions in basal ganglia structures. 总被引:1,自引:0,他引:1
Martin Südmeyer Andreas Saleh Lars Wojtecki Mathias Cohnen Joachim Gross Markus Ploner Harald Hefter Lars Timmermann Alfons Schnitzler 《Movement disorders》2006,21(12):2134-2139
Wilson's disease (WD) is an inherited disorder of copper metabolism yielding marked motor deficits, including a severely disabling tremor. As a structural correlate of the disease, a variety of cerebral abnormalities has been revealed. However, the relationship between motor deficits and cerebral lesions has remained largely unknown. Here, we investigated correlation between WD tremor and cerebral magnetic resonance imaging (MRI) findings. Cerebral MRI abnormalities in 6 symptomatic WD patients were compared to findings in 6 asymptomatic WD patients and 10 healthy controls. All patients were treated with long-term copper chelating therapy. Motor symptoms including tremor were determined by Unified Parkinson's Disease Rating Scale Part III (UPDRS-III). MRI findings in symptomatic WD patients revealed significant symmetric T2*-weighted hypointense signal alterations of globus pallidus, head of the caudate nucleus, and substantia nigra. In contrast, MRI of asymptomatic WD patients did not differ from healthy controls. Correlation analysis revealed a significant positive correlation between MRI basal ganglia lesions and UPDRS action tremor score. Our results demonstrate for the first time that Wilson's disease tremor is associated with lesions of the globus pallidus, the head of the caudate nucleus, and the substantia nigra. 相似文献
998.
目的:评估早期Alzheimer病患者语义记忆损害。方法:自编语义记忆测试工具,对22例Alzheimer病患者语义记忆损害评估作了纵向的研究.其中男10例,女12例。同时进行简明精神状况量表评定。结果:AD患者的2次MMSE评分明显差于正常对照组(P〈O.001)。在两个词的并列关系中,AD患者语义性启动操作起初并不同步。在并列条件测试中.先出现高启动效应.然后下降。在特征条件测试中,始终呈低启动效应。结论:AD病患者有着显著的动态语义记忆退化。 相似文献
999.
1000.
The objective of this study was to test the impact of entacapone (ENT) addition to levodopa with a decarboxylase inhibitor (LD) in full-time-employed patients with Parkinson's disease (PD), focusing on retirement rates, medical absenteeism, self-perception of disability, as well as motor assessments of parkinsonism, motor fluctuations, and dyskinesias. Thirty full-time-employed PD patients (disease onset before age 60 years) and on optimized monotherapy with LD exhibiting minor motor fluctuations or dyskinesias were entered into a 2-year randomized double-blind placebo-controlled study of ENT adjunctive therapy. The outcome measures were the number of full-time-employed patients at study end, cumulative days of medical absenteeism, patient-completed disability assessments, diary records, and the Unified Parkinson's Disease Rating Scale-based measures of motor fluctuations and dyskinesias. LD + ENT treatment was associated with a lower retirement rate (2 [17%] of 12 vs. 6 [50%] of 12; P = 0.12), lower absenteeism rate (21.5 vs. 43.5 days; P < 0.0001), improved self-perception of disability progression over 2 years (change score 1.0 vs. 4.5; P < 0.0001), and lower scores for both motor fluctuations and dyskinesia assessments compared to LD monotherapy. In this pilot study, LD with ENT adjunctive therapy positively influenced employment rate over 2 years; this effect was associated with reduced motor complications and patient perceptions of stabilized disability. 相似文献