全文获取类型
收费全文 | 25500篇 |
免费 | 2190篇 |
国内免费 | 685篇 |
专业分类
耳鼻咽喉 | 212篇 |
儿科学 | 251篇 |
妇产科学 | 603篇 |
基础医学 | 2927篇 |
口腔科学 | 523篇 |
临床医学 | 3272篇 |
内科学 | 2173篇 |
皮肤病学 | 190篇 |
神经病学 | 996篇 |
特种医学 | 1084篇 |
外国民族医学 | 3篇 |
外科学 | 1336篇 |
综合类 | 4111篇 |
现状与发展 | 6篇 |
一般理论 | 5篇 |
预防医学 | 3865篇 |
眼科学 | 313篇 |
药学 | 3350篇 |
74篇 | |
中国医学 | 2030篇 |
肿瘤学 | 1051篇 |
出版年
2024年 | 87篇 |
2023年 | 580篇 |
2022年 | 821篇 |
2021年 | 1384篇 |
2020年 | 1326篇 |
2019年 | 977篇 |
2018年 | 954篇 |
2017年 | 1021篇 |
2016年 | 1106篇 |
2015年 | 1090篇 |
2014年 | 2027篇 |
2013年 | 2280篇 |
2012年 | 1819篇 |
2011年 | 1859篇 |
2010年 | 1361篇 |
2009年 | 1245篇 |
2008年 | 1266篇 |
2007年 | 1081篇 |
2006年 | 943篇 |
2005年 | 771篇 |
2004年 | 655篇 |
2003年 | 566篇 |
2002年 | 443篇 |
2001年 | 373篇 |
2000年 | 283篇 |
1999年 | 230篇 |
1998年 | 197篇 |
1997年 | 179篇 |
1996年 | 160篇 |
1995年 | 155篇 |
1994年 | 141篇 |
1993年 | 86篇 |
1992年 | 111篇 |
1991年 | 85篇 |
1990年 | 86篇 |
1989年 | 61篇 |
1988年 | 72篇 |
1987年 | 75篇 |
1986年 | 41篇 |
1985年 | 75篇 |
1984年 | 66篇 |
1983年 | 52篇 |
1982年 | 42篇 |
1981年 | 36篇 |
1980年 | 38篇 |
1979年 | 19篇 |
1978年 | 8篇 |
1976年 | 8篇 |
1974年 | 7篇 |
1972年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Dmitri Artemov Zaver M. Bhujwalla Ross J. Maxwell John R. Griffiths Ian R. Judson Martin O. Leach Jerry D. Glickson 《Magnetic resonance in medicine》1995,34(3):338-342
The anticancer agent temozolomide labeled with 13C (8-Carbamoyl-3-13C-methylimidazo-[5,1-d]-1,2,3,5-tetrazin-4-(3H)-one), was noninvasively detected in subcutaneous RIF-1 tumors by a selective cross polarization 13C NMR method, at a field strength of 9.4T. Pharmacokinetics of the drug, at a dose of 150 mg/kg, were determined for intravenous and intraperitoneal modes of administration (three animals per mode). The half-life of the drug in the tumors was approximately 60 min. The uptake and clearance of the drug, however, varied significantly between individual hosts, for both modes of administration. These results demonstrate the feasibility of obtaining pharmacokinetics of anticancer agents for individual tumors without the need for a label that might modify drug activity (e.g., fluorine). The variability of the in vivo measurements, even within the same tumor model, demonstrates the necessity of directly monitoring the tumor to evaluate drug pharmacokinetics. 相似文献
62.
63.
我国学术期刊如何应对加入WTO后的机遇与挑战 总被引:4,自引:0,他引:4
针对目前我国学术期刊的发展现状及存在的问题,探讨入世对学术期刊出版的影响,并对我国学术期刊业如何应对入世的挑战提出相应的发展对策和措施。 相似文献
64.
新生儿呕吐性疾病的消化道造影研究 总被引:2,自引:0,他引:2
目的:研究新生儿呕吐性疾病的造影技术,探讨其影像特征。方法:对比剂引入方式采用吸吮法和插胃管抽液后再注入对比剂两种方法;选用对比剂有6 0 %~80 % (W/V)的硫酸钡混悬液30~4 0ml或30 %泛影葡胺30ml;采用不同体位多轴位观察摄片,并对5 4例造影表现进行分析。结果:5 4例新生儿消化道造影均满足诊断要求,其中先天性幽门狭窄11例(19 6 % ) ,胃食管反流34例(6 3 0 % ) ,环形胰腺9例(16 .7% )。经手术治疗2 0例均与术前X线诊断相一致。结论:传统的上消化道造影是诊断新生儿呕吐病因的有效方法,熟练掌握造影技术和特有的造影征像能够及时地明确诊断。 相似文献
65.
66.
OBJECTIVE: To indicate whether the double peaked N(1) to gaps in continuous white noise is a composite of onset and offset responses to transients or whether it reflects higher processing such as change or mismatch detection and to assess the role of attention in this process. METHODS: Evoked potentials were recorded to two binaural stimulus types: (1) gaps of different durations randomly distributed in continuous white noise; and (2) click pairs at intervals identical to those between gap onsets and offsets in the continuous noise stimulus. Potentials to these stimuli were recorded while subjects read a text and while detecting gaps in noise or click pairs. RESULTS: Potentials were detected to all click pairs and to gaps of 5 ms or longer, corresponding to the subjects' psychoacoustic gap detection threshold. With long gap durations of 200-800 ms, distinct potentials to gap onset and gap offset were observed. The waveforms to all click pairs and to offsets of long gaps were similar and single-peaked, while potentials to gaps of 10 ms and longer, and potentials to onsets of long gaps were double-peaked, consisting of two N(1) negativities, 60 ms apart, irrespective of gap duration. The first (N(1a)), was more frontal in its distribution and similar to that of clicks. The second (N(1b)) peak's distribution was more central/temporal and its source locations and time course of activity were distinct. No effects of attention on any of the varieties and constituents of N(1) were observed. CONCLUSIONS: Comparing potentials to gap onsets, to click pairs and to gap offsets, suggests that potentials to gap onsets involve not only sound onset/offset responses (N(1), N(1a)) but also the subsequent pre-attentive perception of the cessation of an ongoing sound (N(1b)). We propose that N(1b) is distinct from change or mismatch detection and is associated with termination of an ongoing continuous stimulus. We propose to call it the N(egation)-process. SIGNIFICANCE: A constituent of the N(1) complex is shown to be associated with the pre-attentive perception of termination of an ongoing stimulus and to have distinct scalp distribution and intracranial sources. 相似文献
67.
Willem G de Voogt Ben F M Vonk Bert A Albers Florian Hintringer 《Europace : European pacing, arrhythmias, and cardiac electrophysiology》2004,6(6):561-569
Automatic capture detection systems are currently available in several cardiac pacing devices. All current systems use low-polarization electrodes and no beat to beat detection system is available for all types of electrodes. In addition the success ratio for currently available systems is not always 100%. Failure to detect capture reliably is often related to the behaviour of the electrode-tissue interface under different circumstances. Pacemaker electrodes can be considered electrochemical cells with complicated characteristics depending on time, temperature and electrical charge. This electrochemical cell is disturbed when a charge is transferred across the electrode-tissue interface during pacing. Several measures can be taken in order to minimise this disturbance or pace polarization artefact (PPA) including the use of high active surface area electrodes and application of tri-phasic pacing pulses. Another factor influencing detection of evoked potentials is the input circuit of the pacemaker affecting the PPA and the evoked response. Positive PPAs can be falsely interpreted as evoked potentials due to the undershoot of the second order filters applied in modern cardiac pacemakers. This paper explains the behaviour of the interface between the electrode and the cardiac tissue in combination with the pacemaker output circuits and input amplifiers under different circumstances. 相似文献
68.
69.
70.
本文将聚乙二醇(PEG)比浊法和固相酶联免疫法(ELISA)结合,建立了—较灵敏的免疫复合物(IC)直接固相吸附抗原特异性检测法。利用牛清蛋白(BSA)为已知抗原组份的IC模型,分别对IC直接固相吸附的条件和影响因素、方法的灵敏度、重复性等进行了研究。结果发现IC在解离状态下直接固相吸附后的抗原特异性检测灵敏度明显高于未解离者。该法具有简单易行,灵敏度较高、适于临床测定大量血清样品等优点。 相似文献