全文获取类型
收费全文 | 14487篇 |
免费 | 833篇 |
国内免费 | 651篇 |
专业分类
耳鼻咽喉 | 45篇 |
儿科学 | 242篇 |
妇产科学 | 135篇 |
基础医学 | 1637篇 |
口腔科学 | 185篇 |
临床医学 | 2425篇 |
内科学 | 1941篇 |
皮肤病学 | 120篇 |
神经病学 | 586篇 |
特种医学 | 477篇 |
外国民族医学 | 1篇 |
外科学 | 1704篇 |
综合类 | 2696篇 |
现状与发展 | 2篇 |
预防医学 | 615篇 |
眼科学 | 107篇 |
药学 | 2186篇 |
7篇 | |
中国医学 | 454篇 |
肿瘤学 | 406篇 |
出版年
2024年 | 18篇 |
2023年 | 143篇 |
2022年 | 294篇 |
2021年 | 493篇 |
2020年 | 397篇 |
2019年 | 333篇 |
2018年 | 374篇 |
2017年 | 372篇 |
2016年 | 373篇 |
2015年 | 415篇 |
2014年 | 813篇 |
2013年 | 981篇 |
2012年 | 799篇 |
2011年 | 801篇 |
2010年 | 764篇 |
2009年 | 688篇 |
2008年 | 748篇 |
2007年 | 775篇 |
2006年 | 726篇 |
2005年 | 695篇 |
2004年 | 611篇 |
2003年 | 566篇 |
2002年 | 462篇 |
2001年 | 363篇 |
2000年 | 318篇 |
1999年 | 291篇 |
1998年 | 251篇 |
1997年 | 247篇 |
1996年 | 243篇 |
1995年 | 227篇 |
1994年 | 167篇 |
1993年 | 137篇 |
1992年 | 113篇 |
1991年 | 113篇 |
1990年 | 112篇 |
1989年 | 82篇 |
1988年 | 68篇 |
1987年 | 58篇 |
1986年 | 47篇 |
1985年 | 76篇 |
1984年 | 64篇 |
1983年 | 42篇 |
1982年 | 58篇 |
1981年 | 42篇 |
1980年 | 46篇 |
1979年 | 31篇 |
1978年 | 25篇 |
1977年 | 20篇 |
1976年 | 25篇 |
1974年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
μ,δ,κ阿片受体在创伤失血性休克大鼠心血管功能抑制中的作用 总被引:3,自引:0,他引:3
目的探讨μ,δ和κ阿片受体与创伤失血性休克大鼠心血管功能抑制的关系。方法用大鼠创伤失血性休克模型,观察创伤失血性休克后大鼠心脏和脑μ,δ和κ阿片受体变化及其与血流动力学指标的变化的关系;观察δ和κ阿片受体特异性拮抗剂对创伤失血性休克大鼠血流动力学指标的影响。结果创伤失血性休克后,大鼠心脏和脑δ和κ阿片受体数目明显升高,亲和力无明显变化,心脏和脑的δ和κ阿片受体数目升高与创伤失血性休克后大鼠血流动力学指标下降呈显著负相关。δ和κ阿片受体特异性拮抗剂可明显逆转创伤失血性休克大鼠血流动力学指标的下降。结论δ和κ阿片受体在创伤失血性休克心血管功能抑制中起重要作用,参与了创伤失血性休克的发病过程 相似文献
62.
A. I. Shapoval 《Bulletin of experimental biology and medicine》1993,115(1):60-63
Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 115, No. 1, pp. 57–59, January, 1993. 相似文献
63.
Background and Objective: Flashlamp pumped dye (FPDL), Q-switched Nd:YAG, and alexandrite lasers are the most clinically used laser lithotriptors. Although calculi are fragmented by laser induced mechanical stresses for all lithotriptors, different fragment sizes and fragmentation efficiencies have been reported. In this work the effect of the pulse duration and pulse shape on the fragmentation processes is studied. Material and Methods: Fragmentation processes are characterized on model stones and on sensing target fibers. Stone fragmentation and cavitation bubble generation are observed by video flash photography. Shock wave occurrence and strength are monitored with an hydrophone. Results: For the FPDL, stone fragmentation is induced by the collapse of the large cavitation bubble formed. For the Q-switched Nd:YAG, fragmentation is already observed during the laser pulse, at the plasma onset, although further fragmentation can occur at the bubble collapse. For pulse durations corresponding to the alexandrite, an intermediate fragmentation regime is observed. Conclusion: For the first time the physical basis of the observed differences in the fragmentation efficiencies of current laser lithotriptors is described. For nanosecond durations the fragmentation processes are governed by plasma induced shock waves. On the contrary, for microsecond durations fragmentation is governed by cavitation. The high fragmentation efficiency of microsecond lasers is due to a high laser energy transfer into cavitation. © 1995 Wiley-Liss, Inc. 相似文献
64.
Hikaru Matsuda Yoshiyuki Taenaka Nobukazu Ohkubo Masakatu Ohtani Kyouichi Nishigaki Shigeaki Ohtake Takuya Miura Nobuyuki Taenaka† Hisateru Takano Hajime Hirose Yasunaru Kawashima 《Artificial organs》1988,12(5):423-430
Pneumatic ventricular assist device (VAD) was utilized for cardiogenic shock after intracardiac operation in two children with complex cardiac anomalies based with single ventricle. In the first case (a 10-year-old), after a modified Fontan operation, VAD was placed between the functional left atrium and ascending aorta, serving as a "artificial single ventricle" with neither pumping chamber nor artificial support in the right side of the heart. The systemic circulation was maintained by keeping relatively high central venous pressure. In another child (a 3-year-old) who underwent repair of incompetent atrioventricular valve leaving intracardiac lesions, VAD was placed between the common atrium and ascending aorta, serving as a pump for both pulmonary and systemic circulation with regulation of pulmonary blood flow through an aortopulmonary Gore-Tex shunt. The circulatory assist with VAD was utilized for 5 and 6 days, respectively. Although weaning from the device was not feasible in both patients because of the pulmonary dysfunction, these experience showed the possible use of VAD for cardiogenic shock after surgery in patients with complex cardiac anomalies. 相似文献
65.
背景 感染性休克患者存在肾脏血液灌注异常,严重时可诱发急性肾损伤(AKI),严重威胁患者生命安全;彩色多普勒超声(CDU)可用于评估肾脏血流变化,但有关其在感染性休克患者AKI评估中价值的研究较少。目的 通过CDU评价感染性休克患者AKI的发生情况及其血流动力学改变。方法 选取2019年6月至2021年7月徐州市中心医院收治的105例确诊为感染性休克的患者并纳入感染组,选取同期健康体检者58例并纳入对照组,收集受试者一般资料。采用CDU检查受试者肾脏血流动力学指标[肾动脉管腔内径(D)、收缩期血流峰值速度(Vs)、舒张末期血流速度(Vd)、阻力指数(RI)、搏动指数(PI)],比较感染组与对照组的一般资料及肾脏血流动力学指标。根据感染组患者入院72 h内发生AKI与否将其分为AKI组及非AKI组,比较AKI组与非AKI组肾脏血流动力学指标。应用受试者工作特征(ROC)曲线分析肾脏血流动力学指标对感染性休克患者发生AKI的预测价值。应用单因素分析及多因素Logistic回归分析探讨感染性休克患者发生AKI的影响因素。以AKI由轻到重的程度将患者分为AKIⅠ组、AKIⅡ组、AKIⅢ组,比较... 相似文献
66.
目的 比较不同能流密度的体外冲击波(extracorporeal shock wave, ESW)治疗肱骨外上髁炎(lateral epicondylitis, LE)的短期临床疗效,探索ESW的最佳治疗剂量。方法 将120例LE患者分为A、B、C和D 4组,均使用ESW治疗4周,各组的能流密度分别为0.06、0.08、0.10、0.12 mJ/mm2。分别在治疗前及治疗后4、24及48周,比较4组患者疼痛视觉模拟量表(visual analogue scale, VAS)评分、肱骨外上髁炎功能评估(patient-rated tennis elbow evaluation, PRTEE)评分及末次随访患者满意度和复发率。结果 按时间点比较,各组VAS评分治疗前最高,治疗后48周降至最低(P<0.05),4组患者满意度及复发率比较差异无统计学意义(P>0.05),但C组患者满意度(96.67%)明显高于A组(80%),差异具有统计学意义(P=0.04)。按组间比较观察,治疗前各组患肘VAS评分差异无统计学意义(P>0.05);治疗后4、24和48... 相似文献
67.
To evaluate the development of renal hypoxia during hemorrhagic shock, fourteen dogs were induced in this study. The animals were divided equally into a group in which mean arterial pressure (MAP) was kept at 50mmHg (group 1), and into another where MAP was kept at 40mmHg for 180mim (group 2). Renal tissue gas tensions were determined by a mass spectrometer. In the 50-mmHg group, renal tissue oxygen tension (PrO
2) dropped for 15min following hemorrhage, remained constant for 90min, then fell further for 150min before a plateau was established. In the 40-mmHg group, the PrO
2 dropped for 90min before reaching a plateau. The second PrO
2 decline occurred at the same level in both the 50-mmHg group and the 40-mmHg group. The point at which the same PrO
2 level occurred for each group suggests the cessation of oxygen consumption and the conditions of renal hypoxia. It is assumed that renal hypoxia occurs in 120min at a MAP of 50-mmHg and in 60min at a MAP of 40mmHg.(Murakawa K, Izumi R, Kobayashi A: Renal tissue gas tentions during hemorrhagic shock. J Anesth 3: 10–15, 1989) 相似文献
68.
Alessandro Daniotti Gaetano Povolo Agata Barchitta Aierken Abudureheman Paolo Cardaioli Cristina Basso 《Cardiovascular pathology》2004,13(6):330-333
A 51-year-old woman suffered rapidly irreversible cardiogenic shock with left hemiparesis. Transesophageal echocardiography, which represents an essential imaging tool in the emergency room, ruled out aortic dissection involving branch vessels but did not allow an in vivo diagnosis of spontaneous coronary dissection. The in vivo diagnosis of spontaneous coronary dissection is rather difficult because of the dramatic clinical presentation and selective coronary angiography requirement. 相似文献
69.
Bernd Schoel Ulrich Zügel Thomas Ruppert Stefan H. E. Kaufmann 《European journal of immunology》1994,24(12):3161-3169
The peptides recognized by an H-2Db-restricted CD8 cytotoxic T lymphocyte (CTL) clone which is specific for the 60-kDa mycobacterial heat shock protein (hsp) and cross-reacts with stressed host cells were characterized. None of the nonapeptides from hsp60 conforming to the H-2Db binding motif were able to sensitize target cells for lysis by this CTL clone. Sequence analysis of the stimulatory fraction from a trypsin digest of hsp60, together with synthetic peptide studies, defined a cluster of overlapping epitopes. Carboxy-terminal extension by at least one amino acid of the nonamer predicted to bind best to H-2Db was essential for CTL recognition. Two such elongated peptides, a 10-mer and a 12-mer stimulated the clone at similarly low concentrations in the 100 pM range. We assume that these two peptides comply best with the natural epitope. In contrast, the 11-mer was inactive. The stimulatory 10-mer bound to H-2Db with an efficacy similar to that of the nonapeptide corresponding to the H-2Db motif, as revealed by peptide induced major histocompatibility complex (MHC) surface expression on RMA-S cells and competitive blocking of epitope recognition by the nonamer. Binding of these carboxy-terminally extended peptides to the MHC groove can be explained by anchoring through the amino acid residue Asn in position 5 of the peptide and by intrusion of the hydrophobic carboxy-terminal Ala (10-mer) or Leu (12-mer), but not Gly (11-mer), into the hydrophobic pocket of the H-2Db cleft. Because the carboxy-terminal part is thus larger than predicted this region of the peptide may arch up from the binding groove. We assume that recognition of steric components of the MHC/peptide complex broaden the range of epitope specificity for a single T cell receptor. This flexibility not only promotes recognition of several overlapping peptides from a single antigen, but may also increase the chance of cross-reaction with similar peptides from unrelated proteins, including autoantigens. Consistent with this latter assumption, the T cell clone cross-recognizes mycobacterial hsp60 and stressed host cells. 相似文献
70.