全文获取类型
收费全文 | 50675篇 |
免费 | 3543篇 |
国内免费 | 860篇 |
专业分类
耳鼻咽喉 | 2371篇 |
儿科学 | 253篇 |
妇产科学 | 95篇 |
基础医学 | 3160篇 |
口腔科学 | 3282篇 |
临床医学 | 4477篇 |
内科学 | 1974篇 |
皮肤病学 | 123篇 |
神经病学 | 696篇 |
特种医学 | 2889篇 |
外国民族医学 | 3篇 |
外科学 | 18374篇 |
综合类 | 7947篇 |
现状与发展 | 2篇 |
预防医学 | 1537篇 |
眼科学 | 227篇 |
药学 | 2454篇 |
73篇 | |
中国医学 | 1845篇 |
肿瘤学 | 3296篇 |
出版年
2024年 | 644篇 |
2023年 | 1092篇 |
2022年 | 1884篇 |
2021年 | 2329篇 |
2020年 | 2487篇 |
2019年 | 2018篇 |
2018年 | 1700篇 |
2017年 | 1882篇 |
2016年 | 2041篇 |
2015年 | 1875篇 |
2014年 | 3674篇 |
2013年 | 3537篇 |
2012年 | 3153篇 |
2011年 | 3418篇 |
2010年 | 2770篇 |
2009年 | 2697篇 |
2008年 | 2405篇 |
2007年 | 2388篇 |
2006年 | 2070篇 |
2005年 | 1900篇 |
2004年 | 1583篇 |
2003年 | 1251篇 |
2002年 | 1009篇 |
2001年 | 871篇 |
2000年 | 671篇 |
1999年 | 602篇 |
1998年 | 528篇 |
1997年 | 446篇 |
1996年 | 296篇 |
1995年 | 261篇 |
1994年 | 216篇 |
1993年 | 197篇 |
1992年 | 153篇 |
1991年 | 119篇 |
1990年 | 75篇 |
1989年 | 77篇 |
1988年 | 72篇 |
1987年 | 67篇 |
1986年 | 62篇 |
1985年 | 71篇 |
1984年 | 65篇 |
1983年 | 63篇 |
1982年 | 75篇 |
1981年 | 68篇 |
1980年 | 55篇 |
1979年 | 43篇 |
1978年 | 35篇 |
1977年 | 26篇 |
1976年 | 23篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
为探讨细胞外间质主要成分透明质酸(HA)与层粘连蛋白(LN)在缺血性股骨头坏死(INFH)中的生理病理过程及临床价值,采用放射免疫分析法对45例不同病因的INFH患者进行了血清HA与LN的定量分析,并与30例正常人对照。结果显示,INFH患者血清HA含量极显著地高于对照组(t=3-29;P<0-01)。尤以激素性INFN增高最为显著(t=3-62;P<0-01)。INFH患者LN含量亦明显高于对照组(t=2-84;P<0-01)。同时,HA与LN含量增高与病程发展密切相关。故定量检测HA与LN可作为INFH早期诊断及判断预后的良好指标 相似文献
42.
Bulletin of Experimental Biology and Medicine - 相似文献
43.
44.
F. L. I. P. Drijber J. B. Finlay T. K. Moroz C. H. Rorabeck 《Medical & biological engineering & computing》1990,28(1):8-14
An investigation was conducted to determine what improvements in the resistance to slippage could be obtained in selected
interfaces (rod/clip torsional, cheek/bowl and cheek/clip) of the Hoffmann external fixator. The modification involved changing
the standard wing-nut clamp for a bolt with a thread of 7 mm and a 1 mm pitch and placing an FAG 28–303 thrust-bearing (needle
roller and cage assembly) between the bolt and the cheek. The results showed a significant improvement in the slippage values
of all interfaces; increases of approximately six times were obtained at all torque values of the wing-nut clamp or fastener
tested. Such improvements would markedly increase the reliability of external fixation systems and thus reduce the incidence
of loss-of-reduction of fracture due to slippage of the universal joint. 相似文献
45.
The anterior talofibular ligament is the most commonly injured ligament in the ankle. Despite considerable interest in the clinical outcome of treatment protocols, we do not know whether the distinctive pattern of localization of the injuries relates to regional differences in the structure and molecular composition of the ligament. To address this issue, ligaments were examined by histology and immunohistochemistry. Differences in the structure of its two attachments (i.e. entheses) were evaluated with quantitative, morphometric techniques, and regional differences in the distribution of collagens, glycosaminoglycans and proteoglycans were determined qualitatively by immunolabelling. Morphometric analyses showed that bone density was less at the fibular attachment, but that enthesis fibrocartilage was more prominent. Immunohistochemistry revealed the presence of a fibrocartilage (containing type II collagen and aggrecan) at the site where the ligament wraps around the lateral talar articular cartilage in a plantarflexed and inverted foot: the fibrocartilage is regarded as an adaptation to resisting compression. We propose that avulsion fractures are less common at the talar end of the ligament because (1) bone density is greater here than at the fibular enthesis, and (2) stress is dissipated away from the talar enthesis by the 'wrap-around' fibrocartilaginous character of the ligament near the talar articular facet. 相似文献
46.
47.
48.
The modulation of monosynaptic forelimb reflexes by tonic neck positions was investigated in cats with the head fixed.Lateral flexion of the body in a horizontal plane markedly facilitates reflexes of the deep radial nerve (DR) in the ipsilateral forelimb, while the antagonistic ulnar nerve (ULN) reflexes are strongly inhibited. Opposite effects are seen after contralateral body movement.Dorsiflexion of the body clearly increases DR-reflexes and exerts a reciprocal although more pronounced inhibition on ULN reflexes. Opposite effects appear after ventriflexion.The reflex modulation starts with head-body displacements of approximately 5° and increases with increasing angles. Furthermore reflex modulation does not depend on the intact cerebrum and cerebellum. The comparison of forelimb and hindlimb reflexes shows a decrease of the neck influences along the spinal cord.Supported by Sonderforschungsbereich Hirnforschung und Sinnes-physiology (SFB 70) der Deutschen Forschungsgemeinschaft (DFG).Essential parts of this paper will be submitted by A. F. as a thesis to the Faculty of Medicine, Freiburg/Breisgau, Germany. 相似文献
49.
Y. Yamagata B. J. Yates V. J. Wilson 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1991,84(2):461-464
Summary As part of our studies of the spinal circuitry of the tonic neck reflex, we have recorded extracellularly from Ia reciprocal inhibitory neurons of the decerebrate, labyrinthectomized cat. The activity of a majority of neurons driven by stimulation of the quadriceps nerve was modulated by sinusoidal rotation of the neck; such modulation was much less frequent in the case of neurons driven by stimulation of nerves to more distal muscles. The results suggest that some of the inhibition which is part of the tonic neck reflex is mediated by Ia reciprocal inhibitory neurons, but that other pathways must also play an important role. 相似文献
50.
Michael P. Cary Farica Zhuang Rachel Lea Draelos Wei Pan Sathya Amarasekara Brian J. Douthit Yunah Kang Cathleen S. Colón-Emeric 《Journal of the American Medical Directors Association》2021,22(2):291-296
ObjectivesTo evaluate a machine learning model designed to predict mortality for Medicare beneficiaries aged >65 years treated for hip fracture in Inpatient Rehabilitation Facilities (IRFs).DesignRetrospective design/cohort analysis of Centers for Medicare & Medicaid Services Inpatient Rehabilitation Facility–Patient Assessment Instrument data.Setting and ParticipantsA total of 17,140 persons admitted to Medicare-certified IRFs in 2015 following hospitalization for hip fracture.MeasuresPatient characteristics include sociodemographic (age, gender, race, and social support) and clinical factors (functional status at admission, chronic conditions) and IRF length of stay. Outcomes were 30-day and 1-year all-cause mortality. We trained and evaluated 2 classification models, logistic regression and a multilayer perceptron (MLP), to predict the probability of 30-day and 1-year mortality and evaluated the calibration, discrimination, and precision of the models.ResultsFor 30-day mortality, MLP performed well [acc = 0.74, area under the receiver operating characteristic curve (AUROC) = 0.76, avg prec = 0.10, slope = 1.14] as did logistic regression (acc = 0.78, AUROC = 0.76, avg prec = 0.09, slope = 1.20). For 1-year mortality, the performances were similar for both MLP (acc = 0.68, AUROC = 0.75, avg prec = 0.32, slope = 0.96) and logistic regression (acc = 0.68, AUROC = 0.75, avg prec = 0.32, slope = 0.95).Conclusion and ImplicationsA scoring system based on logistic regression may be more feasible to run in current electronic medical records. But MLP models may reduce cognitive burden and increase ability to calibrate to local data, yielding clinical specificity in mortality prediction so that palliative care resources may be allocated more effectively. 相似文献