全文获取类型
收费全文 | 16646篇 |
免费 | 1244篇 |
国内免费 | 344篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 202篇 |
妇产科学 | 231篇 |
基础医学 | 773篇 |
口腔科学 | 506篇 |
临床医学 | 3260篇 |
内科学 | 1758篇 |
皮肤病学 | 252篇 |
神经病学 | 446篇 |
特种医学 | 962篇 |
外国民族医学 | 2篇 |
外科学 | 928篇 |
综合类 | 3511篇 |
一般理论 | 2篇 |
预防医学 | 2069篇 |
眼科学 | 473篇 |
药学 | 1477篇 |
101篇 | |
中国医学 | 574篇 |
肿瘤学 | 632篇 |
出版年
2024年 | 69篇 |
2023年 | 337篇 |
2022年 | 662篇 |
2021年 | 899篇 |
2020年 | 911篇 |
2019年 | 574篇 |
2018年 | 532篇 |
2017年 | 620篇 |
2016年 | 702篇 |
2015年 | 618篇 |
2014年 | 1334篇 |
2013年 | 1222篇 |
2012年 | 1115篇 |
2011年 | 1119篇 |
2010年 | 834篇 |
2009年 | 750篇 |
2008年 | 728篇 |
2007年 | 738篇 |
2006年 | 664篇 |
2005年 | 631篇 |
2004年 | 436篇 |
2003年 | 361篇 |
2002年 | 349篇 |
2001年 | 282篇 |
2000年 | 228篇 |
1999年 | 190篇 |
1998年 | 177篇 |
1997年 | 150篇 |
1996年 | 141篇 |
1995年 | 122篇 |
1994年 | 116篇 |
1993年 | 95篇 |
1992年 | 72篇 |
1991年 | 70篇 |
1990年 | 68篇 |
1989年 | 41篇 |
1988年 | 32篇 |
1987年 | 35篇 |
1986年 | 36篇 |
1985年 | 36篇 |
1984年 | 24篇 |
1983年 | 13篇 |
1982年 | 22篇 |
1981年 | 16篇 |
1980年 | 7篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1975年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
C Joseph Muniz Arthur C Fleischer Edwin F Donnelly Murray J Mazer 《Journal of ultrasound in medicine》2002,21(2):129-133
OBJECTIVE: To assess the accuracy of three-dimensional color Doppler sonography and uterine artery arteriography in depicting changes in fibroid vascularity before and after embolization. METHODS: Preembolization and postembolization three-dimensional color Doppler sonography and selective uterine artery arteriography were retrospectively compared in 15 patients who underwent uterine artery embolization for treatment of symptomatic fibroids. Three-dimensional color Doppler sonography was performed by using a scanner with color power angiographic imaging capability. Vascularity was quantified by using an estimation of power-weighted pixel density as described by our group in previously published studies. Uterine artery arteriography was performed by using a standard selective microcatheter embolization technique. For purposes of comparison, fibroids were classified as either hypervascular or hypovascular relative to myometrial vascularity before and minutes to several hours after uterine artery embolization. Changes in fibroid vascularity (i.e., from hypervascular to hypovascular) as depicted by three-dimensional color Doppler sonography were compared with those shown on uterine artery arteriography and classified as being in agreement or disagreement. RESULTS: In 13 (87%) of 15 patients there was agreement; in 2 (13%) of 15 there was disagreement. In both cases of disagreement, three-dimensional color Doppler sonography showed collateral flow not depicted by uterine artery arteriography The mean reduction in quantitated vascularity after uterine artery embolization was 44% (range, 19%-78%). CONCLUSIONS: Three-dimensional color Doppler sonography accurately depicts fibroid vascularity and in some cases can reveal collateral flow not depicted by uterine artery arteriography. 相似文献
62.
在心脏手术中应用多普勒彩色超声心动仪直接探测和观察19例患者,其中风湿性心瓣膜病11例、先天性心脏病7例、左心房粘液瘤1例。风心病及左房粘液瘤患者手术前、中检查的结果基本一致;先心病术前诊断符合率为84.2%(5/7),术中诊断符合率为100%。本文对检查结果作了分析讨论,并提出符合我国情况的有关检查设想。 相似文献
63.
64.
张军 《中华超声影像学杂志》1994,(1)
本文通过应用彩色多普勒及激光荧光染料显示射流方法研究了不同形状界面对射流的影响。结果表明对照组及平坦界面射流时,彩色多普勒与激光荧光染料两种方法无显著差异;在弯曲界面条件下,彩色多普勒射流小于激光荧光染料射流(P<0.01~0.0001)。彩色多普勒研究表明不同形状界面射流大小分别与每搏容量相关好(r=0.83~0.99),但射流大小明显不同。凹形界面射流面积最小,平坦及凸形界面射流面积也小于对照组。研究提示不同形状界面可以导致界面射流不同程度地减小,并且彩色多普勒也不易对弯曲界面的射流完全成像。在临床上应用彩色多普勒对返流定量时,需考虑上述影响。 相似文献
65.
66.
Magnetic susceptibility, as a physical property of materials, plays important roles in many physical, chemical, engineering, and medical applications. Its quantification becomes of significant interest when MRI becomes a commonly used technique in biomedical applications. A general method is presented here for quantifying arbitrary magnetic susceptibility distributions in a localized region on the basis of first principles of magnetic induction field distributions in space. A proof of the concept was demonstrated by computer simulations. The study establishes the methodological basis for quantitative magnetic susceptibility imaging with MR. 相似文献
67.
造影剂到达腹主动脉的峰值大小与患者因素的关系 总被引:3,自引:0,他引:3
目的探讨造影剂到达腹主动脉的峰值大小与患者因素之间的关系。方法108例患者以2.5ml/s注射欧乃派克(300mgI/ml)20ml,12s后采用testbolus技术在腹腔干水平同层动态扫描腹主动脉,用dynamic evaluation软件测得腹主动脉的峰值大小,采用单因素回归分析和多因素逐步回归分析法研究患者的性别、年龄、身高、体重、心率、血压、注射位点、达峰时间及是否有心脏病、糖尿病、或化疗史对造影剂到达腹主动脉峰值大小是否有影响及影响程度。结果造影剂到达腹主动脉峰值大小,在男性平均比女性低;其随年龄、身高、体重、达峰时间的增加而逐渐降低,注射位点在手背静脉其值平均比在肘部静脉低;其不受心率、血压、是否有心脏病、糖尿病或化疗史的影响。参考公式:峰值大小(HU)=383.8400-身高(cm)×1.0909-体重(kg)×0.6760 注射位点×16.7878-达峰时间(s)×1.6882。结论可根据患者的性别、年龄、身高、体重、注射位点和达峰时间来适当调整患者CT血管成像时造影剂用量。 相似文献
68.
目的用彩色多普勒超声观察穿刺性血管损伤的声像图特征。方法26例周围血管穿刺后出现局部肿块、血管杂音,用彩色多普勒超声显示肿块的形态、回声、与周围血管的关系,观察肿块内、破口处、肢体动脉和静脉内的血流信号。结果3例单纯性血肿,彩色血流成像肿块内无血流信号;19例假性动脉瘤,肿块内有低速的动脉血流信号,动脉与肿块的破口处有五彩镶嵌的彩色血流信号和收缩期高速湍流血流频谱;4例动静脉瘘,在瘘口处可见有一股五彩镶嵌的彩色血流信号和连续性高速分流频谱。结论彩色多普勒超声能为穿刺性血管损伤提供准确的诊断。 相似文献
69.
N R Hill P C Hindmarsh R J Stevens I M Stratton J C Levy D R Matthews 《Diabetic medicine》2007,24(7):753-758
AIM: As the practice of multiple assessments of glucose concentration throughout the day increases for people with diabetes, there is a need for an assessment of glycaemic control weighted for the clinical risks of both hypoglycaemia and hyperglycaemia. METHODS: We have developed a methodology to report the degree of risk which a glycaemic profile represents. Fifty diabetes professionals assigned risk values to a range of 40 blood glucose concentrations. Their responses were summarised and a generic function of glycaemic risk was derived. This function was applied to patient glucose profiles to generate an integrated risk score termed the Glycaemic Risk Assessment Diabetes Equation (GRADE). The GRADE score was then reported by use of the mean value and the relative percent contribution to the weighted risk score from the hypoglycaemic, euglycaemic, hyperglycaemic range, respectively, e.g. GRADE (hypoglycaemia%, euglycaemia%, hyperglycaemia%). RESULTS: The GRADE scores of indicative glucose profiles were as follows: continuous glucose monitoring profile non-diabetic subjects GRADE = 1.1, Type 1 diabetes continuous glucose monitoring GRADE = 8.09 (20%, 8%, 72%), Type 2 diabetes home blood glucose monitoring GRADE = 9.97 (2%, 7%, 91%). CONCLUSIONS: The GRADE score of a glucose profile summarises the degree of risk associated with a glucose profile. Values < 5 correspond to euglycaemia. The GRADE score is simple to generate from any blood glucose profile and can be used as an adjunct to HbA1c to report the degree of risk associated with glycaemic variability. 相似文献
70.
多层螺旋CT对冠状动脉粥样硬化斑块的显示结果及与超声结果的比较 总被引:6,自引:0,他引:6
目的评价多层螺旋CT(MSCT)探查无明显管腔狭窄的冠状动脉粥样硬化斑块的能力及准确性。方法共35例连续患者行冠状动脉内超声(IVUS)及16层MSCT检查,其中30例MSCT成像成功。对94支无明显狭窄的冠状动脉节段MSCT及IVUS图像行对照研究,逐一分析每支冠状动脉节段是否出现粥样硬化斑块。IVUS根据斑块回声特点将斑块分为钙化斑块、纤维斑块和软斑块,MSCT则测量斑块密度,以CT值表示。结果对照IVUS结果,MSCT对出现任何粥样硬化斑块节段的诊断敏感性为82.1%(46/56),特异性为89.5%(34/38)。对于含钙化斑块的节段,MSCT诊断敏感性为92.1%(35/38),特异性为96.4%(54/56)。对于含非钙化斑块的节段,MSCT诊断敏感性为73.2%(30/41),特异性为88.7%(47/53)。对于仅含非钙化斑块的节段,MSCT诊断敏感性为66.7%(12/18)。MSCT分析54个斑块平均CT值,按照IVUS分类,钙化斑块19个,纤维斑块19个,软斑块16个,对应CT值分别为:钙化斑块(489±169)HU(196~817HU),纤维斑块(69±21)HU(25~117HU)以及软斑块(23±18)HU(-12~47HU)。非参数Kruskal-Wallis检验显示3组斑块MSCT测量密度CT值间差异有统计学意义(P值均〈0.01);两种方法对斑块面积的测量具有相关性(r=0.58,P〈0.01),MSCT测定斑块平均面积为5.3mm^2,IVUS为5.6mm^2。结论MSCT对无明显管腔狭窄的冠状动脉粥样硬化斑块有良好的探查能力。根据斑块密度(CT值)差异,MSCT能区分不同类型冠状动脉粥样斑块。对斑块面积测量,MSCT与IVUS结果具有相关性。 相似文献