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41.
42.
从制备方法着手综述了近年来聚苯胺/聚合物导电材料研制开发的最新成果,并简介了聚苯胺/聚合物导电材料的应用情况。 相似文献
43.
B C Goss K P McGee E C Ehman A Manduca R L Ehman 《Magnetic resonance in medicine》2006,56(5):1060-1066
Magnetic resonance elastography (MRE) is a phase-contrast technique that can spatially map shear stiffness within tissue-like materials. To date, however, MRE of the lung has been too technically challenging-primarily because of signal-to-noise ratio (SNR) limitations and phase instability. We describe an approach in which shear wave propagation is not encoded into the phase of the MR signal of a material, but rather from the signal arising from a polarized noble gas encapsulated within. To determine the feasibility of the approach, three experiments were performed. First, to establish whether shear wave propagation within lung parenchyma can be visualized with phase-contrast MR techniques, MRE was performed on excised porcine lungs inflated with room air. Second, a phantom consisting of open-cell foam filled with thermally polarized (3)He gas was imaged with MRE to determine whether shear wave propagation can be encoded by the gas. Third, preliminary evidence of the feasibility of MRE in vivo was obtained by using a longitudinal driver on the chest of a normal volunteer to generate shear waves in the lung. The results suggest that MRE in combination with hyperpolarized noble gases is potentially useful for noninvasively assessing the regional elastic properties of lung parenchyma, and merits further investigation. 相似文献
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45.
目的分析并比较NE系列的两种冲击波源碎石机治疗输尿管结石的疗效、碎石时的疼痛程度、碎石时间及副作用。方法回顾性分析应用NE-IV型液电冲击波源碎石机治疗输尿管结石患者1290例及应用NE-VB型电磁冲击波源碎石机治疗输尿管结石患者1196例的临床资料,并进行疗效、碎石时间、碎石时的疼痛程度及副作用的比较。结果应用电磁冲击波源碎石机治疗输尿管上段结石患者的总有效率为85.4%,治疗时间23~60min,平均(35.3±5.7)min;输尿管下段结石患者的总有效率为94.6%,治疗时间3~60min,平均(30.5±6.1)min。碎石时患者的疼痛感觉轻。液电冲击波源碎石机治疗的输尿管上段结石患者的总有效率为75.7%,治疗时间25~110min,平均(38.0±9.8)min;输尿管下段结石为85.7%,治疗时间4~90min,平均(35.8±7.7)min。碎石时患者的疼痛感觉明显。此外,肾绞痛、血尿、恶心、呕吐、皮肤瘀斑等副作用明显高于电磁冲击波源碎石机治疗组。结论电磁冲击波源碎石机治疗输尿管结石疗效优于液电冲击波源碎石机,而且更安全、有效、痛苦小。 相似文献
46.
Pseudo-Oversensing of the T Wave by an Implantable Cardioverter Defibrillator: A Nonclinical Problem
DAVID W. FRAZIER MARSHALL S. STANTON 《Pacing and clinical electrophysiology : PACE》1994,17(7):1311-1315
Two patients are described who had pseudo-oversensing of T waves during follow-up testing of the Medtronic PCD. Each patient exhibited appropriate T wave sensing following closely coupled spontaneous QRS complexes to subthreshold stimuli without having T wave sensing following sensed or paced complexes. One patient also revealed T wave sensing following fusion beats. The occurrence of T wave sensing in these unique clinical situations was due to the auto-adjusting sensitivity threshold function used by the PCD. Recognition of this normal sensing function will prevent inappropriate reprogramming of the sensitivity or postpace refractory period, interventions that could potentially lead to ventricular tachyarrhythmia undersensing. 相似文献
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48.
Summary. Background: Pathological shear stress induces platelet aggregation that is dependent on von Willebrand factor (VWF) binding to glycoprotein (Gp)Ib‐IX‐V and phosphatidylinositol 3‐kinase activation. We tested the hypothesis that pathological shear stress stimulates phosphatidylinositol 3,4,5‐trisphosphate (PIP3) synthesis by directing the assembly of a molecular signaling complex that includes class IA phosphatidylinositol 3‐kinase (PI 3‐KIA). Methods: Platelets were subjected to 120 dynes cm?2 shear stress in a cone‐plate viscometer. Resting and sheared platelets were lyzed, immunoprecipitations of PI 3‐KIA performed, or lipids extracted for PIP3 measurements. α‐Actinin was incubated with phosphatidylinositol 4,5‐bisphosphate (PIP2), immunoprecipitated, and used as a substrate for in vitro PI 3‐KIA activity. Results: Pathological shear stress induces biphasic PIP3 production. In resting platelets, PI 3‐KIA associates with α‐actinin and PIP2. After exposure to shear stress, α‐actinin and PIP2 rapidly disassociate from PI 3‐KIA. PI 3‐KIA then gradually re‐associates with PIP2 and α‐actinin, and this complex becomes linked to GpIbα through the cytoskeleton. PIP3 production and the observed changes in the association between α‐actinin, PIP2, and PI 3‐KIA are inhibited when VWF binding to GpIbα is blocked. In a cell‐free system, α‐actinin binds PIP2 and when the α‐actinin–PIP2 complex is added to platelet PI 3‐KIA, PIP3 production is stimulated. Conclusions: These results suggest that pathological shear‐induced VWF binding to GpIb‐IX‐V stimulates PIP3 production through the assembly of an α‐actinin‐based complex that colocalizes PI 3‐KIA with substrate PIP2. 相似文献
49.
枣花丹合剂对失眠症夜间慢波睡眠影响的研究 总被引:1,自引:0,他引:1
目的:观察枣花丹合剂对失眠症夜间慢波睡眠的影响。方法:选择无器质性病变,每天睡眠少于240~300min为主症者64例患者随机分为两组。枣花丹合剂组在08:00和19:00时分别服用枣花丹合剂200mL。对照组在08:00和19:00时服同量红糖水,连服4周。睡眠监测的数据包括记录时间、非快动眼睡眠期、快动眼睡眠期、睡眠时间、觉醒时间、睡眠比、觉醒比。结果:枣花丹合剂组与对照组相比,夜间睡眠Ⅰ、Ⅱ期减少,Ⅲ、Ⅳ期增加;夜间觉醒次数减少,总睡眠时间明显增加;SWS睡眠结构比改变,SWS睡眠的连续性好、周期性显著,明显优于对照组改变,差异有统计学意义(P<0.05)。结论:枣花丹合剂可以增加失眠症夜间慢波睡眠,是治疗失眠症的一种有效和较好治疗方法。 相似文献
50.
目的探讨缺氧诱导因子-1α(HIF-1α)在ESWL致肾脏损伤中的作用及黄芪是否通过调节HIF-1α的表达而发挥对肾脏的保护作用。方法45只家兔随机分为对照组、ESWL损伤组和黄芪治疗组,每组15只,除对照组外,所有动物接受ESWL处理(18kV,1 500次)。黄芪治疗组家兔于冲击前3d至后2d,每天注射黄芪注射液2.0g/kg。2周后处死家兔,取肾脏HE染色观察肾组织形态学改变,免疫组织化学染色观察HIF-1α在肾脏中的表达。结果ESWL处理后肾小管上皮细胞肿胀、脱落,小管内可见大量管型,肾间质大量炎细胞浸润;黄芪治疗组以上病变显著减轻。ESWL损伤组HIF-1α显著表达于肾小管上皮细胞及间质,黄芪能够明显抑制HIF-1α的表达。结论HIF-1α参与了ESWL对肾脏的损伤,黄芪可能通过抑制HIF-1α的表达发挥对肾脏的保护作用。 相似文献