全文获取类型
收费全文 | 148466篇 |
免费 | 12514篇 |
国内免费 | 6995篇 |
专业分类
耳鼻咽喉 | 1026篇 |
儿科学 | 4440篇 |
妇产科学 | 3277篇 |
基础医学 | 17823篇 |
口腔科学 | 3437篇 |
临床医学 | 13571篇 |
内科学 | 23438篇 |
皮肤病学 | 2057篇 |
神经病学 | 10502篇 |
特种医学 | 3285篇 |
外国民族医学 | 43篇 |
外科学 | 13756篇 |
综合类 | 24080篇 |
现状与发展 | 21篇 |
预防医学 | 11205篇 |
眼科学 | 4391篇 |
药学 | 13970篇 |
47篇 | |
中国医学 | 5839篇 |
肿瘤学 | 11767篇 |
出版年
2024年 | 377篇 |
2023年 | 1776篇 |
2022年 | 3976篇 |
2021年 | 5126篇 |
2020年 | 4529篇 |
2019年 | 4362篇 |
2018年 | 4339篇 |
2017年 | 4851篇 |
2016年 | 5064篇 |
2015年 | 5160篇 |
2014年 | 9069篇 |
2013年 | 10367篇 |
2012年 | 9122篇 |
2011年 | 10247篇 |
2010年 | 8575篇 |
2009年 | 8296篇 |
2008年 | 8570篇 |
2007年 | 8598篇 |
2006年 | 7629篇 |
2005年 | 6840篇 |
2004年 | 5802篇 |
2003年 | 4996篇 |
2002年 | 4124篇 |
2001年 | 3584篇 |
2000年 | 3025篇 |
1999年 | 2562篇 |
1998年 | 2172篇 |
1997年 | 1919篇 |
1996年 | 1788篇 |
1995年 | 1577篇 |
1994年 | 1344篇 |
1993年 | 1102篇 |
1992年 | 978篇 |
1991年 | 794篇 |
1990年 | 744篇 |
1989年 | 574篇 |
1988年 | 442篇 |
1987年 | 389篇 |
1986年 | 358篇 |
1985年 | 502篇 |
1984年 | 424篇 |
1983年 | 280篇 |
1982年 | 370篇 |
1981年 | 249篇 |
1980年 | 235篇 |
1979年 | 154篇 |
1978年 | 127篇 |
1977年 | 112篇 |
1976年 | 105篇 |
1975年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Terry Reed 《Clinical genetics》1991,39(5):391-395
Evidence from the literature is reviewed to suggest that when fingertip dermal ridge patterns in chromosomal deletion syndromes are characteristic of the opposite spectrum of the developmental scale from patterns found in cases trisomic for the same chromosomal region, the association may be a consequence of loci with growth regulatory functions. Evidence is presented that DNA markers at 18q21 should be the first candidate sequences to be used to test this hypothesis in families with fingertip arches segregating in an apparent autosomal dominant fashion. 相似文献
72.
An atypical variant of reflex sympathetic dystrophy (RSD) is presented in a 45 year old female with a vascular malformation
of the right arm and chest wall. The mechanism was thought to be compression of the brachial plexus by the malformation. The
unique scintigraphic features of this presentation of RSD in the ulnar arterial distribution are illustrated. 相似文献
73.
74.
75.
Paul J. J. M. Plasmans Martin A. van 't Hof 《Community dentistry and oral epidemiology》1987,15(4):192-196
The treatment times for the fabrication of Extensive Amalgam Restorations (EAR) as recorded in a longitudinal clinical trial at the Dental School in Nijmegen were analyzed. 269 EAR's with different retention methods were made on molars by three operators. A mean total treatment time of 60 min was found. The factor operator had a significant influence on all treatment phases resulting in a 26% difference in total treatment time between operators. Also significant influences were found in some treatment phases for the factor retention, side location of the tooth and extension of the restoration. The results of this study with regard to treatment times must be considered from the perspective of the quality of the care provided. 相似文献
76.
Bone mineral “density” (BMD) measured by dual-energy X-ray absorptiometry (DEXA) does not represent the volumetric density (grams per cubic centimeter), but rather the areal density (grams per square centimeter). This distinction is important during growth. The purpose of this study was to measure vertebral dimensions in cadavers of young pigtail macaques (Macaca nemestrina), and to derive equations to predict the volumetric bone density from noninvasive measurements. We measured the areal bone density by DEXA, vertebral volume by underwater weighing, mineral content by ashing, dimensions of lumbar vertebrae by calipers, and dimensions of vertebrae by radiography. Somatometric measurements of the female lumbar vertebral bodies showed that the shape changed during growth. The bone mineral content from the densitometer correlated significantly with the ash weight (r = 0.99, error 8.7%). The correlation coefficient between the volumetric bone mineral density and areal BMD measurement was significant (r = 0.68, p < 0.0001) with a 9.5% error; this improved significantly to 0.82 (7.2% error) when the BMD was divided by the vertebral depth from the radiograph. Areal BMD showed a strong correlation with age (r = 0.82, p < 0.0001), with an average increase of 7.4%/year. In contrast, volumetric mineral density showed a weak relationship with age (r = 0.43, p < 0.01), for an average increase of 1.5%/year. When studying bone mineral density during growth, the differences between volumetric and areal bone mineral density should be taken into consideration. ( 相似文献
77.
An infant is presented who at birth met criteria consistent with hypoplastic left heart syndrome. He was followed clinically and by 11 weeks of age demonstrated substantial growth of the left ventricle. He underwent successful repair of coarctation of the aorta and continues to do well with moderate aortic stenosis. The difficulties of predicting left ventricular growth and function are discussed, and management options are reviewed. 相似文献
78.
穹隆-海马伞切断对大鼠脑内TrkA表达的影响 总被引:1,自引:0,他引:1
①目的 探讨穹隆 海马伞切断对大鼠脑内不同部位神经生长因子受体TrkA表达的影响及临床意义。②方法 成年健康雌性Wistar大鼠 10只 ,随机分为穹隆 海马伞切断模型组和假手术组。两组大鼠均常规取海马CA1区、皮质区、杏仁复合体区、基底前脑Meynert核等部位脑组织与假手术组比较TrkA阳性细胞表达情况。③结果 假手术组大脑各观察区有基础水平的TrkA表达。模型组大脑海马CA1区、大脑皮质区、杏仁复合体区以及Meynert核区TrkA阳性细胞数明显减少 (t=3.94 4~ 8.4 4 2 ,P <0 .0 5 )。 ④结论 穹隆 海马伞切断可致大鼠脑内多部位TrkA表达减少 ,其可能是导致认知和情绪损伤的原因之一。 相似文献
79.
肺癌组织中血管内皮生长因子受体Flt1及KDR的表达及其与肿瘤转移和预后的关系 总被引:1,自引:1,他引:0
①目的 探讨肺癌中血管内皮生长因子受体Flt1、KDR的表达与其转移及预后的关系。②方法 应用免疫组织化学PowerVisionTM PV90 0 0法 ,测定 75例肺癌标本中Flt1、KDR的表达。③结果 肺癌组织中Flt1、KDR的表达较为广泛 ,主要位于肿瘤细胞胞浆及胞膜上 ,纤维母细胞和血管内皮细胞胞浆中亦有表达。Flt1、KDR在肿瘤细胞中的阳性率均显著高于在间质纤维母细胞中的表达 (χ2 =6 .0 7、5 .88,P <0 .0 5 )。肿瘤细胞及纤维母细胞中该两种受体的阳性率在不同年龄、不同性别及不同病理类型、不同病理分级之间差异均无显著性 (χ2 =0 .0 1~4 .84 ,P >0 .0 5 ;P =0 .2 9~ 0 .79)。肿瘤细胞中Flt1、KDR的阳性表达率在 3组不同大小的肿瘤间差异均有显著性(χ2 =1 0 .35、7.2 9,P <0 .0 5 ) ,而纤维母细胞中差异均无显著性 (χ2 =2 .86、2 .5 6 ,P >0 .0 5 ) ;肿瘤细胞及纤维母细胞中Flt1、KDR的阳性率在淋巴结有、无转移两组间的差异均有显著性 (χ2 =4 .72~ 9.32 ,P <0 .0 5 ) ,在 3组不同术后生存时间病人间亦均有显著性差异 (χ2 =8.81~ 1 9.1 9,P <0 .0 5 )。肿瘤细胞中Flt1、KDR的表达呈极显著性正相关 (r =0 .4 4 ,P <0 .0 1 )。④结论 肺癌的生长主要依赖自分泌机制 ,联合检测Flt1、KDR可能对肺癌转移 相似文献
80.
参附注射液对肠缺血-再灌注大鼠肿瘤坏死因子α的影响 总被引:5,自引:0,他引:5
目的观察肿瘤坏死因子α(TNF-α)在大鼠肠缺血-再灌注损伤过程中的作用及参附注射液对TNF-α的影响,探讨参附注射液防治肠缺血-再灌注损伤机制。方法 SD大鼠随机分为肠缺血-再灌注组(IR组)、参附注射液预处理组(SF组)和假手术组(C组)。采用阻断肠系膜上动脉(SMA)的方法制造肠缺血-再灌注模型。分别测定各组动物血浆、肠组织TNF-α含量及血液动力学变化;光镜观察肠粘膜损伤情况。结果IR组再灌注后MAP下降,与C组和SF组比有显著性差异(P<0.01);SF组肠粘膜损伤程度减轻,与IR组比有显著性差异(P<0.01);SF组血浆及肠组织TNF-α水平降低,与IR组比有显著性差异(P<0.01)。结论参附注射液可明显防治大鼠肠缺血-再灌注导致的肠粘膜损伤,这种作用可能是通过抑制TNF-α的释放实现的。 相似文献