全文获取类型
收费全文 | 14104篇 |
免费 | 876篇 |
国内免费 | 506篇 |
专业分类
耳鼻咽喉 | 141篇 |
儿科学 | 293篇 |
妇产科学 | 102篇 |
基础医学 | 977篇 |
口腔科学 | 109篇 |
临床医学 | 969篇 |
内科学 | 998篇 |
皮肤病学 | 59篇 |
神经病学 | 230篇 |
特种医学 | 347篇 |
外科学 | 3305篇 |
综合类 | 2372篇 |
预防医学 | 996篇 |
眼科学 | 24篇 |
药学 | 2098篇 |
10篇 | |
中国医学 | 1962篇 |
肿瘤学 | 494篇 |
出版年
2024年 | 46篇 |
2023年 | 259篇 |
2022年 | 587篇 |
2021年 | 657篇 |
2020年 | 523篇 |
2019年 | 494篇 |
2018年 | 486篇 |
2017年 | 491篇 |
2016年 | 500篇 |
2015年 | 516篇 |
2014年 | 1032篇 |
2013年 | 920篇 |
2012年 | 1004篇 |
2011年 | 1027篇 |
2010年 | 743篇 |
2009年 | 724篇 |
2008年 | 719篇 |
2007年 | 789篇 |
2006年 | 592篇 |
2005年 | 543篇 |
2004年 | 423篇 |
2003年 | 313篇 |
2002年 | 260篇 |
2001年 | 246篇 |
2000年 | 211篇 |
1999年 | 167篇 |
1998年 | 141篇 |
1997年 | 109篇 |
1996年 | 93篇 |
1995年 | 103篇 |
1994年 | 94篇 |
1993年 | 81篇 |
1992年 | 64篇 |
1991年 | 64篇 |
1990年 | 52篇 |
1989年 | 38篇 |
1988年 | 50篇 |
1987年 | 43篇 |
1986年 | 29篇 |
1985年 | 31篇 |
1984年 | 32篇 |
1983年 | 45篇 |
1982年 | 31篇 |
1981年 | 26篇 |
1980年 | 22篇 |
1979年 | 20篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1975年 | 8篇 |
1973年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
The cold pressor test: Vascular and myocardial response patterns and their stability 总被引:2,自引:0,他引:2
PATRICE G. SAAB MARIA M. LLABRE BARRY E. HURWITZ NEIL SCHNEIDERMAN WILLIAM WOHLGEMUTH LYNN A. DUREL CLIFFORD MASSIE JOACHIM NAGEL 《Psychophysiology》1993,30(4):366-373
The purposes of the present study were to compare the cardiovascular response patterns evoked by three versions of the cold pressor test (either forehead stimulation or hand or foot immersion) and to determine the reproducibility of the responses over a 2-week interval. Blood pressure, heart rate, stroke volume, cardiac output, total peripheral resistance, and systolic time intervals were obtained during rest and during the cold pressor test in 42 young men. Across conditions, the pressor response was supported by peripheral resistance increases with concomitant stroke volume decreases. Although the response panerns were generally similar across sites, exceptions were apparent for heart rate. Forehead stimulation was characterized by no significant change in heart rate, whereas limb (hand or foot) immersion was associated with significant heart rate acceleration. The responses elicited by the three cold pressor test conditions were reliable and showed little evidence of attenuation over the test-retest interval. 相似文献
43.
44.
本文通过分析近5年来我院18例女性直肠癌全直肠系膜切除术后直肠阴道痿的临床资料。发现直肠阴道痿多发生于中低位直肠癌行全直肠系膜切除保肛手术的患者。痿的发生与肿瘤的位置、肿瘤的分期、肿瘤距肛门口的距离.以及手术技巧、手术难度、引流方法有关。而与是否进行预防性造口,以及是否采用腹腔镜手术无关。预防上强调应重视术中直肠前壁的锐性分离、结肠直肠吻合以及术后盆腔的负压引流。治疗上应首先进行保守治疗,即肠内营养,阴道冲洗。早期配合肠外营养、及全身或局部抗炎治疗,大部分直肠阴道痿通过保守治疗可以治愈。保守治疗无效时考虑结肠或回肠末端造口。若长期不愈应考虑吻合口肿瘤复发的可能。 相似文献
45.
为了验证冲击式二级粉尘采样对呼吸性粉尘与总粉尘浓度比值的影响,作者采用瞬时定点采样方法测定作业场所空气中呼吸性粉尘浓度与总粉尘浓度。结果表明,在采样体积相同的条件下,呼吸性粉尘的比值与总粉尘浓度间具有较好的从属共变关系(r>0.8),呼吸性粉尘的比值随着总粉尘浓度的升高而相应增大 相似文献
46.
Background
The effect of the changes in the femoral posterior condylar offset (PCO) on anterior–posterior (AP) translation and internal–external (IE) rotation in cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) remains unknown. The purpose of this study was to compare the kinematics in CR and PS TKA with respect to the difference in prosthetic design and PCO change through a computational simulation.Methods
We developed three-dimensional finite element models with the different PCOs of ± 1, ± 2 and ± 3?mm in the posterior direction using CR and PS TKA. We performed the simulation with different PCOs under a deep knee bend condition and evaluated the kinematics for the AP and IE in CR and PS TKA.Results
The more tibiofemoral (TF) translation in the posterior direction was found as PCO translated in posterior direction for both CR and PS TKA compared to the neutral position. However, the change of the AP translation with respect to the PCO change in CR TKA was greater than PS TKA. The more TF external rotation was found as PCO translated in the anterior direction for both CR and PS TKA compared to the neutral position. However, unlike the TF translation, the TF rotation was not influenced by the PCO change in both CR and PS TKA.Conclusion
The PCO magnitude was influenced by a postoperative change in the kinematics in CR TKA although a relatively smaller effect was observed in PS TKA. Hence, surgeons should be aware of the PCO change, especially for CR TKA. 相似文献47.
Boisgard S Moreau PE Descamps S Courtalhiac C Silbert H Moreel P Michel JL Levai JP 《Surgical and radiologic anatomy : SRA》2003,25(3-4):330-334
The epicondylar axis is a reliable reference to check the rotation of the femoral implant in total knee prostheses (TKPs). However, during the operation it seems easier to use the posterior condylar axis as a landmark. The angle between these two axes is called the posterior condylar angle (PCA). The aim of this study was to measure the PCA in arthritic knees to assess the reliability of the posterior condylar axis as a reference for the control of the rotation of the femoral implant and to look for correlation with other radiological measurements. This prospective study consisted of 103 arthritic knees (81 varus, 22 valgus) before a TKP had been done in 103 patients (75 women, 28 men). The assessment of the PCA was made by computed tomographic scanning (CT). The HKA, HKS and HKT angles were measured on the pangonogram. The posterior condylar axis was internally rotated with respect to the epicondylar axis. The average value for all the patients was 2.65° degrees with a range from 0° to 7°. The PCA was significantly increased in the valgus knees. There was no correlation between the angles on the pangonogram and the posterior condylar axis. While the preoperative assessment of the PCA by CT scanning is reliable, the results obtained indicate the marked variability in its value. If one wishes to use the posterior condylar axis as a guide for rotation, it is therefore necessary to assess the PCA for each patient using adjustable jigs according to the value obtained. No measurement on standard radiographs allowed an extrapolation of the value of the PCA, and CT scanning seems to be the preferable radiological examination.
Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at
Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at
Etude tomodensitométrique de l'angle condylien postérieur dans les genoux arthrosiques. Intérêt dans le positionnement en rotation de l'implant fémoral dans les prothèses totales de genou
Résumé L'axe épicondylien est une référence fiable pour le contrôle de la rotation de l'implant fémoral dans les prothèses totales de genou (PTG). Mais, lors de l'intervention, il semble plus facile d'utiliser l'axe condylien postérieur comme repère. L'angle entre ses deux axes est appelé angle condylien postérieur (ACP). Le but de cette étude était de mesurer l'ACP dans les genoux arthrosiques, d'évaluer la fiabilité de l'axe condylien postérieur comme référence pour le réglage de la rotation de l'implant fémoral, de rechercher une corrélation avec d'autres mesures radiologiques. Une étude prospective comportant 103 genoux arthrosiques (81 varus et 22 valgus), avant PTG a été effectuée, chez 103 patients (75 femmes et 28 hommes). L'évaluation de l'ACP a été faite par examen tomodensitométrique (TDM). Les angles HKA, HKS et HKT ont été mesurés sur le pangonogramme. L'axe condylien postérieur était en rotation interne par rapport à l'axe épicondylien. La valeur moyenne pour tous les patients était de 2.65°, avec des valeurs de 0 à 7°. La valeur de l'angle CP augmentait avec une différence significative dans le groupe des genu valgum. Il n'y avait pas de corrélation entre les angles du pangonogramme et l'ACP. Si l'évaluation pré-opératoire de l'ACP par TDM est fiable, les résultats obtenus mettent en évidence une variabilité importante de sa valeur. Il faut donc, si l'on veut utiliser l'axe condylien postérieur comme repère de rotation, évaluer pour chaque patient l'ACP, et utiliser un ancillaire réglable reportant la valeur obtenue. Aucune mesure sur des radiographies standard ne permettant d'extrapoler la valeur de l'ACP, la TDM semble l'examen radiologique de choix.相似文献
48.
Braakman R. Sipkema P. Westerhof N. 《Pflügers Archiv : European journal of physiology》1986,407(4):432-439
It has been reported that sodiumnitroprusside (SNP) decreases mean systemic pressure and simultaneously increases pressure pulse amplification towards the iliac periphery (Kenner and van Zwieten 1982). This unexpected finding was suggested to be due to a decrease in iliac peripheral resistance but an increase in iliac differential resistance. In order to investigate this apparent contradiction, the iliac periphery was hemodynamically isolated from the rest of the circulation and perfused with the dog's own blood by means of a pump. Perfusion pressure (P) and flow (F), femoral venous pressure (Pv), systemic pressure (Ps) and cardiac output (CO) were measured. Steady state pressure-flow relations of the isolated bed were obtained during control and during various i.v. infusion rates of SNP and adenosine (ADS) and were found to be straight (meanr=0.99). Their slope (P/F) was defined as differential resistance (Rd). Peripheral resistance (Rp) of the iliac bed was defined as Rp=(P-Pv)/F, calculated at the flow value where perfusion pressure equalled the prevailing systemic pressure. Total peripheral resistance (TPR) was defined as TPR=Ps/CO. The changes of Rd, Rp, Ps, CO and TPR with respect to control show that during low SNP infusion rates Rd and Rp were both increased while TPR was decreased. During all infusion rates of SNP CO did not change while Ps decreased. During low infusion rates of adenosine CO increased while Ps, Rd and Rp did not change and TPR decreased. During high infusion rates of ADS CO decreased again, Rd, Rp and Ps decreased, and TPR remained constant but at a decreased level.It is concluded that: (1) the suggestion of Kenner and van Zwieten is not supported, since SNP (as well as ADS) affects iliac peripheral and iliac differential resistance in a similar way; (2) SNP (as well as ADS) affects iliac peripheral resistance and total peripheral resistance in a differentiated way, and even in an opposite way during low infusion rates of SNP; (3) it is this opposite effect that explains the paradoxical observations of Kenner and van Zwieten; (4) for comparable reductions of TPR, CO is better maintained during infusion of SNP, while Ps is better maintained during infusion of ADS. 相似文献
49.
A new one-step computational procedure is presented for estimating the parameters of the nonlinear three-element windkessel
model of the arterial system incorporating a pressure-dependent compliance. The data required are pulsatile aortic pressure
and flow. The basic assumptions are a steadystate periodic regime and a purely elastic compliant element. By stating two conditions,
zero mean flow and zero mean power in the compliant element, peripheral and characteristic resistances are determined through
simple closed form formulas as functions of mean values of the square of aortic pressure, the square of aortic flow, and the
product of aortic pressure with aortic flow. The pressure across as well as the flow through the compliant element can be
then obtained so allowing the calculation of volume variation and compliance as functions of pressure. The feasibility of
this method is studied by applying it to both simulated and experimental data relative to different circulatory conditions
and comparing the results with those obtained by an iterative parameter optimization algorithm and with the actual values
when available. The conclusion is that the proposed method appears to be effective in identifying the three-element windkessel
even in the case of nonlinear compliance. 相似文献
50.
Dr. B. K. van Kreel N. Cox-Reyven P. Soeters 《Medical & biological engineering & computing》1998,36(3):337-345
Multifrequency bio-electronic impedance analysis (MF BIA) measurements are taken from a heterogeneous group of patients, varying
in size between obese and slim. The measuring system uses four electrodes: two current and two potential electrodes. Three
new models are developed to calculate total body water (TBW) from the BIA data, and the resulting TBW values are compared
with TBW determined by D2O dilution. The results demonstrate that the most simple model provides the best TBW values. For individual patients, TBW
can be determined by means of bioimpedance measurement with an accuracy of 3 litres. In the most simple model (model 1), the
body is electrically represented by a cylinder, and corrections are made for the amount of fat. This is an extension of the
model used by Xitron. In the more advanced models (2 and 3), the body is represented by a cylinder for the trunk, and truncated
cones represent the arms and legs. In model 2, ΔTBW amounts to 3 litres. It is shown that the resistance of the trunk is proportional
to the square root of the length. In model 3, it is assumed that subcutaneous fat is a poor conductor if electric current.
An equation is developed that describes the partition of subcutaneous fat, and the fat layer is then removed from the cones
representing arms and legs and from the cylinder that models the trunk. 相似文献