全文获取类型
收费全文 | 1541篇 |
免费 | 142篇 |
国内免费 | 66篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 39篇 |
妇产科学 | 6篇 |
基础医学 | 227篇 |
口腔科学 | 20篇 |
临床医学 | 136篇 |
内科学 | 221篇 |
皮肤病学 | 4篇 |
神经病学 | 282篇 |
特种医学 | 40篇 |
外科学 | 59篇 |
综合类 | 200篇 |
预防医学 | 59篇 |
眼科学 | 21篇 |
药学 | 243篇 |
中国医学 | 164篇 |
肿瘤学 | 16篇 |
出版年
2023年 | 19篇 |
2022年 | 27篇 |
2021年 | 81篇 |
2020年 | 74篇 |
2019年 | 47篇 |
2018年 | 60篇 |
2017年 | 54篇 |
2016年 | 75篇 |
2015年 | 69篇 |
2014年 | 111篇 |
2013年 | 118篇 |
2012年 | 91篇 |
2011年 | 105篇 |
2010年 | 71篇 |
2009年 | 70篇 |
2008年 | 63篇 |
2007年 | 73篇 |
2006年 | 60篇 |
2005年 | 49篇 |
2004年 | 39篇 |
2003年 | 29篇 |
2002年 | 30篇 |
2001年 | 31篇 |
2000年 | 25篇 |
1999年 | 27篇 |
1998年 | 22篇 |
1997年 | 24篇 |
1996年 | 17篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 16篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 16篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1749条查询结果,搜索用时 234 毫秒
1.
《Cancer cell》2022,40(10):1223-1239.e6
2.
目的:建立黄芪与板蓝根2种根类药材醇沉絮体的分形维数测定方法。方法:分别以黄芪、板蓝根的水提醇沉絮体为研究对象,采用大津算法对醇沉絮体原始显微图像进行二值化处理,运用周长-面积法分别考察沉淀絮体取样体积、稀释倍数、图像放大倍数及图像采集位点数对分形维数的影响。结果:黄芪与板蓝根醇沉絮体均具有分形特征;确定这2个醇沉絮体取样体积在600~800μL,样品稀释至5~20倍,显微图像放大200倍或400倍,选取4个图像采集位点时,能够得到稳定可靠的醇沉絮体分形维数。结论:建立的测定方法稳定可行,可为根类药材醇沉絮体的分形理论研究提供参考。 相似文献
3.
《European journal of surgical oncology》2020,46(1):155-159
IntroductionElectrostatic precipitation Pressurized IntraPeritoneal Aerosol Chemotherapy (ePIPAC) has shown superior penetration depth and tissue uptake compared to standard PIPAC. We investigated the feasibility and objective tumor response to ePIPAC with 1 min of precipitation in patients with peritoneal metastasis (PM).Materials and methodsPatients with PM from various abdominal cancers were included in an amendment to the ongoing prospective PIPAC-OPC2 trial. Colorectal and appendiceal PM were treated with oxaliplatin, patients with PM from other primaries were treated with a combination of cisplatin and doxorubicin. Three ePIPAC procedures were planned in each patient including repeated peritoneal biopsies for response evaluation. After emission to the peritoneal cavity, the aerosolized chemotherapeutics were precipitated for 1 min followed by immediate exsufflation and abdominal closure. Histological regression from the first to the third ePIPAC was evaluated according to the Peritoneal Regression Grading Score (PRGS) and compared to data from the PIPAC-OPC1 trial. Complications and toxicities were recorded according to Dindo-Clavien and CTCAE.ResultsSixty-five ePIPAC procedures were performed in 33 patients (median 2, range 1–6). Ten patients were eligible for response evaluation based on biopsies from the first and third ePIPAC procedure. Four patients had disease progression, four patients had regressive disease, and two patients had stable disease according to PRGS. No life threatening adverse reactions and no mortality was observed following ePIPAC.ConclusionOne minute ePIPAC was feasible and safe, but the histological tumor response was insufficient compared to standard PIPAC directed therapy with 30 min passive diffusion time. 相似文献
4.
《Clinical neurophysiology》2019,130(1):128-137
ObjectiveHigh frequency oscillations (HFO) between 80–500 Hz are markers of epileptic areas in intracranial and maybe also scalp EEG. We investigate simultaneous recordings of scalp and intracranial EEG and hypothesize that scalp HFOs provide important additional clinical information in the presurgical setting.MethodsSpikes and HFOs were visually identified in all intracranial scalp EEG channels. Analysis of correlation of event location between intracranial and scalp EEG as well as relationship between events and the SOZ and zone of surgical removal was performed.Results24 patients could be included, 23 showed spikes and 19 HFOs on scalp recordings. In 15/19 patients highest scalp HFO rate was located over the implantation side, with 13 patients having the highest scalp and intracranial HFO rate over the same region. 17 patients underwent surgery, 7 became seizure free. Patients with poor post-operative outcome showed significantly more regions with HFO than those with seizure free outcome.ConclusionsScalp HFOs are mostly located over the SOZ. Widespread scalp HFOs are indicative of a larger epileptic network and associated with poor postsurgical outcome.SignificanceAnalysis of scalp HFO add clinically important information about the extent of epileptic areas during presurgical simultaneous scalp and intracranial EEG recordings. 相似文献
5.
以低平均气道压和小潮气量为主要特征的高频震荡通气(HFOV),自出现以来备受医务、科研人员的关注。本文就HFOV通气技术方面的研究现状与发展趋势进行了分析和展望,重点介绍与分析了有关HFOV的通气模型、通气机制和通气模式方面的研究现状。并藉此提出,在未来一段时期内,对HFOV通气技术的研究将主要集中在三个方面:建立多级、高阶、非线性的黏性阻力、惯性阻力和顺应性(RIC)通气模型;更为充分地揭示HFOV之所以能够有效通气的机制;研究实现低风险的无创HFOV。对HFOV通气技术的研究与发展,将为呼吸系统疾病患者提供一种不同于常频通气的通气方式。 相似文献
6.
Na Ta Muhammad Umer Bilal Ines Husler Alaukik Saxena Yueh-Yu Lin Felix Schleifer Michael Fleck Uwe Glatzel Birgit Skrotzki Reza Darvishi Kamachali 《Materials》2021,14(5)
The effects of anisotropic interfacial properties and heterogeneous elasticity on the growth and ripening of plate-like θ′-phase (Al2Cu) in Al-1.69 at.% Cu alloy are studied. Multi-phase-field simulations are conducted and discussed in comparison with aging experiments. The precipitate/matrix interface is considered to be anisotropic in terms of its energy and mobility. We find that the additional incorporation of an anisotropic interfacial mobility in conjunction with the elastic anisotropy result in substantially larger aspect ratios of the precipitates closer to the experimental observations. The anisotropy of the interfacial energy shows comparably small effect on the precipitate’s aspect ratio but changes the interface’s shape at the rim. The effect of the chemo-mechanical coupling, i.e., the composition dependence of the elastic constants, is studied as well. We show that the inverse ripening phenomenon, recently evidenced for δ’ precipitates in Al-Li alloys (Park et al. Sci. Rep. 2019, 9, 3981), does not establish for the θ′ precipitates. This is because of the anisotropic stress fields built around the θ′ precipitates, stemming from the precipitate’s shape and the interaction among different variants of the θ′ precipitate, that disturb the chemo-mechanical effects. These results show that the chemo-mechanical effects on the precipitation ripening strongly depend on the degree of sphericity and elastic isotropy of the precipitate and matrix phases. 相似文献
7.
目的:通过系统评价研究低频重复经颅磁刺激(low frequency repetitive transcranial magnetic stimulation,LF-rTMS)对脑卒中后失语症(post stroke aphasia,PSA)患者语言功能的干预疗效。方法:计算机检索Pubmed、Embase、Cochrane library、中国知网(CNKI)、万方数据库(WanFang)、维普数据库(VIP)和中国生物医学文献数据库(CBM)中关于rTMS治疗PSA的随机对照试验,文献检索时限限定为从建库至2020年11月。由2名研究员独立按照纳入、排除标准筛选文献,并完成提取数据,核对数据和质量评价等过程,最终采用RevMan 5.3软件进行Meta分析以及相关结果展示。结果:本研究共纳入11篇随机对照试验,共纳入301例PSA患者。试验组干预措施为:常规言语康复训练结合LF-rTMS,对照组干预措施为:常规言语康复训练结合LF-rTMS假刺激。分析结果显示:相较于对照组,经LF-rTMS治疗后,试验组听理解评分(SMD=0.37,95%CI(0.07,0.67),P=0.02)、复述评分(SMD=0.36,95%CI(0.09,0.64),P=0.01)、命名评分(SMD=0.40,95%CI(0.17,0.63),P=0.00007)均显著提高(P<0.05);试验组与对照组相比具有统计学意义。结论:总结已有相关研究,LF-rTMS治疗对改善PSA患者的语言功能具有明显的效果,对于听理解、复述、命名能力均有显著改善效果。但总体样本量较小,仍需大样本、多中心、以及科学规范化的高质量随机对照试验,进一步完善LF-rTMS治疗PSA患者语言功能的疗效验证。 相似文献
8.
9.
《Brain stimulation》2019,12(5):1261-1270
BackgroundThe motor potentials evoked by transcranial magnetic stimulation (TMS) over the motor hand area (M1-HAND) show substantial inter-trial variability. Pericentral mu-rhythm oscillations, might contribute to inter-trial variability. Recent studies targeting mu-activity based on real-time electroencephalography (EEG) reported an influence of mu-power and mu-phase on the amplitude of motor evoked potentials (MEPs) in a preselected group with strong pericentral mu-activity. Other studies that determined mu-power or mu-phase based on post-hoc trial sorting according in non-preselected individuals were largely negative.ObjectivesTo reassess if cortico-spinal activity is modulated by the mu-rhythm, we applied single-pulse TMS to the M1-HAND conditional on the phase of the intrinsically expressed pericentral mu-rhythm in 14 non-preselected healthy young participants.MethodsTMS was given at 0, 90, 180, and 270° of the mu-phase. Based on the absence of effects of mu-phase or mu-power when analyzing the mean MEP amplitudes, we also computed a linear mixed effects model, which included mu-phase, mu-power, inter-stimulus interval (ISIs) as fixed effects, treating the subject factor as a random effect.ResultsMixed model analysis revealed a significant effect of mu-power and ISI, but no effect of mu-phase and no interactions. MEP amplitude scaled linearly with lower mu-power or longer ISIs, but these modulatory effects were very small relative to inter-trial MEP variability.ConclusionOur largely negative results are in agreement with previous offline TMS-EEG studies and point to a possible influence of ISI. Future research needs to clarify under which circumstances the responsiveness of human the M1-HAND to TMS depends on the synchronicity with mu-power and mu-phase. 相似文献
10.
《Brain stimulation》2021,14(1):55-65
BackgroundTemporal interference (TI) stimulation of the brain generates amplitude-modulated electric fields oscillating in the kHz range with the goal of non-invasive targeted deep brain stimulation. Yet, the current intensities required in human (sensitivity) to modulate deep brain activity and if superficial brain region are spared (selectivity) at these intensities remains unclear.ObjectiveWe developed an experimentally constrained theory for TI sensitivity to kHz electric field given the attenuation by membrane low-pass filtering property, and for TI selectivity to deep structures given the distribution of modulated and unmodulated electric fields in brain.MethodsThe electric field threshold to modulate carbachol-induced gamma oscillations in rat hippocampal slices was determined for unmodulated 0.05–2 kHz sine waveforms, and 5 Hz amplitude-modulated waveforms with 0.1–2 kHz carrier frequencies. The neuronal effects are replicated with a computational network model to explore the underlying mechanisms, and then coupled to a validated current-flow model of the human head.ResultsAmplitude-modulated electric fields are stronger in deep brain regions, while unmodulated electric fields are maximal at the cortical regions. Both experiment and model confirmed the hypothesis that spatial selectivity of temporal interference stimulation depends on the phasic modulation of neural oscillations only in deep brain regions. Adaptation mechanism (e.g. GABAb) enhanced sensitivity to amplitude modulated waveform in contrast to unmodulated kHz and produced selectivity in modulating gamma oscillation (i.e. Higher gamma modulation in amplitude modulated vs unmodulated kHz stimulation). Selection of carrier frequency strongly affected sensitivity to amplitude modulation stimulation. Amplitude modulated stimulation with 100 Hz carrier frequency required ∼5 V/m (corresponding to ∼13 mA at the scalp surface), whereas, 1 kHz carrier frequency ∼60 V/m (∼160 mA) and 2 kHz carrier frequency ∼80 V/m (∼220 mA) to significantly modulate gamma oscillation. Sensitivity is increased (scalp current required decreased) for theoretical neuronal membranes with faster time constants.ConclusionThe TI sensitivity (current required at the scalp) depends on the neuronal membrane time-constant (e.g. axons) approaching the kHz carrier frequency. TI selectivity is governed by network adaption (e.g. GABAb) that is faster than the amplitude-modulation frequency. Thus, we show neuronal and network oscillations time-constants determine the scalp current required and the selectivity achievable with TI in humans. 相似文献