全文获取类型
收费全文 | 101573篇 |
免费 | 9854篇 |
国内免费 | 3022篇 |
专业分类
耳鼻咽喉 | 697篇 |
儿科学 | 2835篇 |
妇产科学 | 788篇 |
基础医学 | 6389篇 |
口腔科学 | 578篇 |
临床医学 | 15266篇 |
内科学 | 23393篇 |
皮肤病学 | 574篇 |
神经病学 | 4659篇 |
特种医学 | 4248篇 |
外国民族医学 | 9篇 |
外科学 | 9191篇 |
综合类 | 20188篇 |
现状与发展 | 4篇 |
预防医学 | 6397篇 |
眼科学 | 966篇 |
药学 | 10039篇 |
131篇 | |
中国医学 | 5948篇 |
肿瘤学 | 2149篇 |
出版年
2024年 | 151篇 |
2023年 | 1727篇 |
2022年 | 2799篇 |
2021年 | 4779篇 |
2020年 | 4978篇 |
2019年 | 4046篇 |
2018年 | 3828篇 |
2017年 | 4293篇 |
2016年 | 4356篇 |
2015年 | 3954篇 |
2014年 | 7306篇 |
2013年 | 7502篇 |
2012年 | 6141篇 |
2011年 | 6361篇 |
2010年 | 5251篇 |
2009年 | 4765篇 |
2008年 | 4714篇 |
2007年 | 4917篇 |
2006年 | 4387篇 |
2005年 | 3768篇 |
2004年 | 3063篇 |
2003年 | 2683篇 |
2002年 | 2252篇 |
2001年 | 2101篇 |
2000年 | 1705篇 |
1999年 | 1460篇 |
1998年 | 1141篇 |
1997年 | 1057篇 |
1996年 | 967篇 |
1995年 | 1015篇 |
1994年 | 917篇 |
1993年 | 699篇 |
1992年 | 748篇 |
1991年 | 590篇 |
1990年 | 524篇 |
1989年 | 440篇 |
1988年 | 422篇 |
1987年 | 388篇 |
1986年 | 322篇 |
1985年 | 356篇 |
1984年 | 331篇 |
1983年 | 192篇 |
1982年 | 221篇 |
1981年 | 158篇 |
1980年 | 130篇 |
1979年 | 127篇 |
1978年 | 122篇 |
1977年 | 71篇 |
1976年 | 76篇 |
1975年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
91.
Susan C. Fox Jane A. May Natalia Dovlatova Jackie R. Glenn Andrew Johnson Ann E. White 《Platelets》2019,30(3):290-295
Measurement of P-selectin on activated platelets as a means of measuring platelet function utilizing the technology described here has the advantage of not requiring immediate access to specialist equipment and expertise. Blood samples are activated, fixed, stored, and transported to a central laboratory for flow cytometric analysis. Here we have compared P-selectin with other more traditional approaches to measuring platelet function in blood and/or platelet-rich plasma (PRP) from patients with acute coronary syndromes on treatment for at least 1 month with either aspirin and clopidogrel or aspirin with prasugrel. The comparators were light transmission aggregometry (LTA), VerifyNow and Multiplate aggregometry (for determining the effects of aspirin) and LTA, VerifyNow and Multiplate together with the BioCytex VASP phosphorylation assay (for the P2Y12 antagonists). The P-selectin Aspirin Test revealed substantial inhibition of platelet function in all but three of 96 patients receiving aspirin with clopidogrel and in none of 51 patients receiving aspirin and prasugrel. The results were very similar to those obtained using LTA. There was only one patient with high residual platelet aggregation and low P-selectin expression. The same patients identified as “non-responders” to aspirin also presented with the highest residual platelet activity as measured using the VerifyNow system, although not quite as well separated from the other values. With the Multiplate test only one of these patients clearly stood out from the others. The results obtained using the P-selectin P2Y12 Test in 102 patients taking aspirin and clopidogrel were similar to the more traditional approaches in that a wide scatter of results was obtained. Generally, high values seen with the P-selectin P2Y12 Test were also high with the LTA, VerifyNow, Multiplate, and BioCytex VASP P2Y12 Tests. Similarly, low residual platelet function using the P2Y12 test was seen irrespective of the testing procedure used. However, there were differences in some patients. Prasugrel was always more effective than clopidogrel in inhibiting platelet function with none of 56 patients (P-selectin and VerifyNow), only 2 of 56 patients (Multiplate) and only 3 of 56 patients (Biocytex VASP) demonstrating high on-treatment residual platelet reactivity (HRPR) defined using previously published cut-off values. The exception was LTA where there were 11 of 56 patients with HRPR. It remains to be seen which experimental approach provides the most useful information regarding outcomes after adjusting therapies in treated patients. 相似文献
92.
Yoh Sugawara Yusuke Mizuno Shinya Oku Takahisa Goto 《British journal of anaesthesia》2019,122(4):437-447
Background
A pulmonary hypertensive crisis (PHC) can be a life-threatening condition. We established a PHC model by exposing rats with monocrotaline (MCT)-induced pulmonary hypertension to acute hypoxia, and investigated the effects of vasopressin, phenylephrine, and norepinephrine on the PHC.Methods
Four weeks after MCT 60 mg kg?1 administration i.v., right ventricular systolic pressure (RVSP), systolic BP (SBP), mean BP (MBP), cardiac index (CI), and pulmonary vascular resistance index (PVRI) were measured. PHC defined as an RVSP exceeding or equal to SBP was induced by changing the fraction of inspiratory oxygen to 0.1. Rats were subsequently treated by vasopressin, phenylephrine, or norepinephrine, followed by assessment of systemic haemodynamics, isometric tension of femoral and pulmonary arteries, cardiac function, blood gas composition, and survival.Results
PHC was associated with increased RV dilatation and paradoxical septal motion. Vasopressin increased MBP [mean (standard error)] from 52.6 (3.8) to 125.0 (8.9) mm Hg and CI from 25.4 (2.3) to 40.6 (1.8) ml min?1 100 g?1 while decreasing PVRI. Vasopressin also improved RV dilatation, oxygenation, and survival in PHC. In contrast, phenylephrine increased MBP from 54.8 (2.3) to 96.8 (3.2) mm Hg without improving cardiac pump function. Norepinephrine did not alter MBP. Vasopressin contracted femoral but not pulmonary arteries, whereas phenylephrine contracted both arterial beds. Hence, improvements with vasopressin in PHC might be associated with decreased PVRI and selective systemic vasoconstriction.Conclusions
In this rat model of a PHC, vasopressin, but not phenylephrine or norepinephrine, resulted in better haemodynamic and vascular recovery. 相似文献93.
94.
The main aim of the paper is to discuss current knowledge on how Age Related Macular Degeneration (AMD) affects Dark Adaptation (DA). The paper is divided into three parts. Firstly, we outline some of the molecular mechanisms that control DA. Secondly, we review the psychophysical issues and the corresponding analytical techniques. Finally, we characterise the link between slowed DA and the morphological abnormalities in early AMD.Historically, DA has been regarded as too cumbersome for widespread clinical application. Yet the technique is extremely useful; it is widely accepted that the psychophysically obtained slope of the second rod-mediated phase of the dark adaptation function is an accurate assay of photoreceptor pigment regeneration kinetics. Technological developments have prompted new ways of generating the DA curve, but analytical problems remain. A simple potential solution to these, based on the application of a novel fast mathematical algorithm, is presented. This allows the calculation of the parameters of the DA curve in real time.Improving current management of AMD will depend on identifying a satisfactory endpoint for evaluating future therapeutic strategies. This must be implemented before the onset of severe disease. Morphological changes progress too slowly to act as a satisfactory endpoint for new therapies whereas functional changes, such as those seen in DA, may have more potential in this regard. It is important to recognise, however, that the functional changes are not confined to rods and that building a mathematical model of the DA curve enables the separation of rod and cone dysfunction and allows more versatility in terms of the range of disease severity that can be monitored. Examples are presented that show how analysing the DA curve into its constituent components can improve our understanding of the morphological changes in early AMD. 相似文献
95.
《Journal of the American Medical Directors Association》2022,23(8):1375-1382.e3
ObjectivesTo identify the optimal cutoff points for poor physical function [measured by a 5-times sit-to-stand (5-STS) test] associated with slowness in community-dwelling older adults and to validate the 5-STS cut points by determining whether they predicted future slowness and clinically relevant health outcomes over a 2-year-follow-up period.DesignCross-sectional and longitudinal analyses of a cohort study.Setting and ParticipantsWe conducted cross-sectional (n = 2977) and prospective 2-year follow-up analyses (n = 2515) among participants aged 70-84 years enrolled in the nationwide Korean Frailty and Aging Cohort Study (KFACS).MethodsClassification and regression tree (CART) analysis was used to identify the 5-STS cut points for poor performance in terms of slowness (eg, gait speed ≥1.0 m/s, gait speed >0.8 m/s and <1.0 m/s, gait speed ≤0.8 m/s) at baseline. Multinomial logistic regression models were used to evaluate the prevalence and incidence of slowness and clinical outcomes according to the three 5-STS categories (normal, intermediate, and poor) in the cross-sectional and longitudinal analyses.ResultsThe overall prevalence of slowness in our study sample was 9.0% for a gait speed of ≤0.8 m/s and 32.1% for a gait speed of <1.0 m/s. The CART model identified 5-STS cut points of 10.8 seconds and 12.8 seconds for intermediate and poor physical function, respectively. In the adjusted model, the cut point of 12.8 seconds had a significantly increased likelihood of incident slowness and clinically relevant health outcomes (ie, mobility limitation, disability, frailty, sarcopenia risk, and falls) over the 2-year-follow-up period (all, P < .05).Conclusions and ImplicationsOur study established 5-STS test cutoff points for poor physical function. Thresholds of 10.8 and 12.8 seconds (intermediate and poor physical function, respectively) for a 5-STS test might help identify individuals at risk of physical function impairments and, thus, help design preventive interventions in community health care settings. 相似文献
96.
97.
98.
99.
目的:基于突触可塑性观察电针曲池、足三里对大脑中动脉闭塞(MCAO)大鼠运动障碍的改善。方法:将60只雄性SD大鼠随机分为假手术组、模型组、穴位组、非穴组,每组15只。采用Zea Longa线拴法制备MCAO大鼠模型,电针曲池、足三里,干预14 d。通过神经功能评分判断大鼠的神经功能缺损情况;CatWalk步态分析比较各组大鼠运动功能,TTC染色观察脑梗死体积,透射电镜观察突触超微结构和数量,免疫荧光检测缺血侧运动皮层突触相关因子突触后致密物-95(PSD-95)、突触蛋白的表达情况。结果:干预14 d后,与模型组比较,穴位组大鼠神经功能评分降低(P<0.05);步行速度提高、双足支撑时间缩短(P<0.05);脑梗死体积减少(P<0.05);突触超微结构改善明显,突触数量增加(P<0.05),突触相关因子突触蛋白、PSD-95表达上调(P<0.05)。Catwalk步态参数、脑梗死体积与突触超微结构改善有一致性。结论:电针曲池、足三里穴可改善MCAO大鼠运动障碍,其机制可能与上调突触相关因子的表达,改善突触可塑性有关。 相似文献
100.
淋巴管作为循环系统的重要组成部分之一,具有调节机体体液稳态,协助免疫监视和肠道脂质吸收等重要作用。淋巴管新生是机体生理和病理过程中维持脉管系统结构和功能正常的重要手段,淋巴管新生调控对于防治肿瘤、心血管等诸多疾病有着潜在的临床转化意义;淋巴回流功能则与关节炎症等疾病发病机制关系密切。在循环系统中,相较于中医药调控血管相关疾病的发病机制已取得很大进展,近年来对于淋巴管的研究则明显相对滞后。本文从中医药作用于淋巴管新生及回流功能角度对这一领域的研究进展作一综述,以期为临床上中医药治疗相关疾病提供新的思路与方法。 相似文献