全文获取类型
收费全文 | 1717篇 |
免费 | 183篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 33篇 |
儿科学 | 50篇 |
妇产科学 | 12篇 |
基础医学 | 116篇 |
口腔科学 | 10篇 |
临床医学 | 183篇 |
内科学 | 280篇 |
皮肤病学 | 31篇 |
神经病学 | 462篇 |
特种医学 | 265篇 |
外科学 | 187篇 |
综合类 | 49篇 |
现状与发展 | 20篇 |
预防医学 | 81篇 |
眼科学 | 26篇 |
药学 | 57篇 |
中国医学 | 3篇 |
肿瘤学 | 52篇 |
出版年
2024年 | 7篇 |
2023年 | 45篇 |
2021年 | 19篇 |
2020年 | 24篇 |
2019年 | 13篇 |
2018年 | 55篇 |
2017年 | 48篇 |
2016年 | 35篇 |
2015年 | 52篇 |
2014年 | 54篇 |
2013年 | 68篇 |
2012年 | 36篇 |
2011年 | 57篇 |
2010年 | 62篇 |
2009年 | 84篇 |
2008年 | 63篇 |
2007年 | 59篇 |
2006年 | 68篇 |
2005年 | 36篇 |
2004年 | 50篇 |
2003年 | 47篇 |
2002年 | 50篇 |
2001年 | 65篇 |
2000年 | 56篇 |
1999年 | 50篇 |
1998年 | 47篇 |
1997年 | 50篇 |
1996年 | 78篇 |
1995年 | 57篇 |
1994年 | 30篇 |
1993年 | 45篇 |
1992年 | 27篇 |
1991年 | 30篇 |
1990年 | 37篇 |
1989年 | 43篇 |
1988年 | 35篇 |
1987年 | 30篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1984年 | 8篇 |
1983年 | 16篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 18篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1975年 | 12篇 |
1964年 | 5篇 |
排序方式: 共有1917条查询结果,搜索用时 15 毫秒
61.
Analysis of expression of cholecystokinin in dopamine cells in the ventral mesencephalon of several species and in humans with schizophrenia. 总被引:3,自引:0,他引:3
M Schalling K Friberg K Seroogy P Riederer E Bird S N Schiffmann P Mailleux J J Vanderhaeghen S Kuga M Goldstein et al. 《Proceedings of the National Academy of Sciences of the United States of America》1990,87(21):8427-8431
The ventral mesencephalons of hamster, guinea pig, cat, monkey, and several humans with and without the diagnosis of schizophrenia were analyzed with in situ hybridization and immunohistochemistry. Extensive codistribution of cholecystokinin mRNA and tyrosine hydroxylase [L-tyrosine, tetrahydropteridine: oxygen oxidoreductase (3-hydroxylating), EC 1.14.16.2] mRNA was observed in cats and monkeys as well as in all five human subjects with the diagnosis of schizophrenia and in two out of five control brains. Double labeling revealed coexistence of the two markers in cat, monkey, and human. No cholecystokinin mRNA or cholecystokinin peptide was detected in the substantia nigra/ventral tegmental area of the hamster or guinea pig, even after acute and chronic neuroleptic treatment. 相似文献
62.
Andrea K. Vaags PhD Sarah Bowdin BM MSc MRCPCH Mary‐Lou Smith PhD Brigitte Gilbert‐Dussardier MD Katja S. Brocke‐Holmefjord MD Katia Sinopoli PhD CPsych Cindy Gilles MSc Tove B. Haaland MD Catherine Vincent‐Delorme MD Emmanuelle Lagrue MD Radu Harbuz MD Susan Walker PhD Christian R. Marshall PhD Gunnar Houge MD PhD Vera M. Kalscheuer PhD Stephen W. Scherer PhD Berge A. Minassian MD 《Annals of neurology》2014,76(5):758-764
Synaptic function is central to brain function. Understanding the synapse is aided by studies of patients lacking individual synaptic proteins. Common neurological diseases are genetically complex. Their understanding is likewise simplified by studies of less common monogenic forms. We detail the disease caused by absence of the synaptic protein CNKSR2 in 8 patients ranging from 6 to 62 years old. The disease is characterized by intellectual disability, attention problems, and abrupt lifelong language loss following a brief early childhood epilepsy with continuous spike‐waves in sleep. This study describes the phenotype of CNKSR2 deficiency and its involvement in systems underlying common neurological disorders. Ann Neurol 2014;76:758–764 相似文献
63.
V Aerra M Kuduvalli AN Moloto AK Srinivasan AD Grayson BM Fabri AY Oo 《Journal of cardiothoracic surgery》2006,1(1):6-5
Background
Atrial fibrillation can occur in up to 40% of patients undergoing coronary surgery. 相似文献64.
65.
Dependence of venous enhancement on the field of view in 3D contrast-enhanced MRA using the elliptical centric view order. 总被引:1,自引:0,他引:1
The dependence of venous suppression on the acquisition field of view (FOV) in elliptical centric 3D contrast-enhanced magnetic resonance angiography (CE-MRA) is studied theoretically and experimentally. It is hypothesized that a reduced FOV in an arterial phase acquisition results in improved venous suppression. An expression is derived linking the k-space representation of a vein to venous return time and acquisition parameters. For a y x z FOV reduction from 24 cm x 7.2 cm to 18 cm x 3.6 cm, equivalent voxel size, and venous return times ranging from 0-7 s, the mean improvement in venous suppression ranged from 7.0% for the 19-mm-diameter vein to 32.1% in the 6-mm-diameter vein, assuming a step function-shaped venous enhancement profile. Decreased venous enhancement with reduced FOV is also observed for scans with equivalent acquisition times, although the degree of suppression is dependent on the shape of the venous enhancement curve. 相似文献
66.
Tara S Beattie Parinita Bhattacharjee Shajy Isac HL Mohan Milena Simic-Lawson BM Ramesh James F Blanchard Stephen Moses Charlotte H Watts Lori Heise 《Journal of the International AIDS Society》2015,18(1)
Introduction
Female sex workers (FSWs) frequently experience violence, harassment and arrest by the police or their clients, but there is little evidence as to the impact that such factors may have on HIV risk or whether community interventions could mitigate this impact.Methods
As part of the evaluation of the Avahan programme in Karnataka, serial integrated behavioural and biological assessment (IBBA) surveys (four districts) (2005 to 2011) and anonymous polling booth surveys (PBS) (16 districts) (2007 to 2011) were conducted with random samples of FSWs. Logistic regression analysis was used to assess 1) changes in reported violence and arrests over time and 2) associations between violence by non-partners and police arrest and HIV/STI risk and prevalence. Mediation analysis was used to identify mediating factors.Results
5,792 FSWs participated in the IBBAs and 15,813 participated in the PBS. Over time, there were significant reductions in the percentages of FSWs reporting being raped in the past year (PBS) (30.0% in 2007, 10.0% in 2011, p<0.001), being arrested in the past year [adjusted odds ratio (AOR) 0.57 (0.35, 0.93), p=0.025] and being beaten in the past six months by a non-partner (clients, police, pimps, strangers, rowdies) [AOR 0.69 (0.49, 0.95), p=0.024)] (IBBA). The proportion drinking alcohol (during the past week) also fell significantly (32.5% in 2005, 24.9% in 2008, 16.8% in 2011; p<0.001). Violence by non-partners (being raped in the past year and/or beaten in the past six months) and being arrested in the past year were both strongly associated with HIV infection [AOR 1.59 (1.18, 2.15), p=0.002; AOR 1.91 (1.17, 3.12), p=0.01, respectively]. They were also associated with drinking alcohol (during the past week) [AOR 1.98 (1.54, 2.53), p<0.001; AOR 2.79 (1.93, 4.04), p<0.001, respectively], reduced condom self-efficacy with clients [AOR 0.36 (0.27, 0.47), p<0.001; AOR 0.62 (0.39, 0.98), p=0.039, respectively], symptomatic STI (during the past year) [AOR 2.62 (2.07, 3.30), p<0.001; AOR 2.17 (1.51, 3.13), p<0.001, respectively], gonorrhoea infection [AOR 2.79 (1.51, 5.15), p=0.001; AOR 2.69 (0.96, 7.56), p=0.060, respectively] and syphilis infection [AOR 1.86 (1.04, 3.31), p=0.036; AOR 3.35 (1.78, 6.28), p<0.001, respectively], but not with exposure to peer education, community mobilization or HIV testing uptake. Mediation analysis suggests that alcohol use and STIs may partially mediate the association between violence or arrests and HIV prevalence.Discussion
Violence by non-partners and arrest are both strongly associated with HIV infection among FSWs. Large-scale, comprehensive HIV prevention programming can reduce violence, arrests and HIV/STI infection among FSWs. 相似文献67.
68.
Joshua D. Trzasko Clifton R. Haider Eric A. Borisch Norbert G. Campeau James F. Glockner Stephen J. Riederer Armando Manduca 《Magnetic resonance in medicine》2011,66(4):1019-1032
Cartesian Acquisition with Projection‐Reconstruction‐like sampling is a SENSE‐type parallel 3DFT acquisition paradigm for 4D contrast‐enhanced magnetic resonance angiography that has been demonstrated capable of providing high spatial and temporal resolution, diagnostic‐quality images at very high acceleration rates. However, Cartesian Acquisition with Projection–Reconstruction‐like sampling images are typically reconstructed online using Tikhonov regularization and partial Fourier methods, which are prone to exhibit noise amplification and undersampling artifacts when operating at very high acceleration rates. In this work, a sparsity‐driven offline reconstruction framework for Cartesian Acquisition with Projection‐Reconstruction‐like sampling is developed and demonstrated to consistently provide improvements over the currently‐employed reconstruction strategy against these ill‐effects. Moreover, the proposed reconstruction strategy requires no changes to the existing Cartesian Acquisition with Projection–Reconstruction‐like sampling acquisition protocol, and an efficient numerical optimization and hardware system are described that allow for a 256 × 160 × 80 volume contrast‐enhanced magnetic resonance angiography volume to be reconstructed from an eight‐channel data set in less than 2 min. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc. 相似文献
69.
Simultaneous image acquisition utilizing hybrid body and phased array receiver coils. 总被引:2,自引:0,他引:2
A Kocharian J P Felmlee K P McGee S J Riederer R L Ehman 《Magnetic resonance in medicine》2000,44(4):660-663
In clinical MR imaging the design and selection of receiver coil is an important step in ensuring the highest image quality. Often this choice is based on selecting a receiver coil characterized by high spatial uniformity such as the body and head volume receiver coils or a surface coil (or array of coils) that provide high signal-to-noise ratio (SNR). In the past, it has been difficult to accomplish both high SNR and spatial uniformity as both coil types achieve one of these characteristics at the expense of the other. The purpose of this study was to achieve both high SNR and spatial uniformity through the simultaneous acquisition of the MR signal using the body and a surface coil array. Results indicate that this hybrid system can provide uniformity and SNR values comparable to those achieved by the body and surface coil arrays, respectively. 相似文献
70.