全文获取类型
收费全文 | 47046篇 |
免费 | 2705篇 |
国内免费 | 854篇 |
专业分类
耳鼻咽喉 | 277篇 |
儿科学 | 1639篇 |
妇产科学 | 987篇 |
基础医学 | 5520篇 |
口腔科学 | 1309篇 |
临床医学 | 2897篇 |
内科学 | 8526篇 |
皮肤病学 | 547篇 |
神经病学 | 3390篇 |
特种医学 | 1385篇 |
外国民族医学 | 2篇 |
外科学 | 5283篇 |
综合类 | 3567篇 |
一般理论 | 3篇 |
预防医学 | 4845篇 |
眼科学 | 532篇 |
药学 | 6155篇 |
22篇 | |
中国医学 | 2407篇 |
肿瘤学 | 1312篇 |
出版年
2023年 | 473篇 |
2022年 | 584篇 |
2021年 | 1109篇 |
2020年 | 996篇 |
2019年 | 2535篇 |
2018年 | 2373篇 |
2017年 | 1546篇 |
2016年 | 1058篇 |
2015年 | 1209篇 |
2014年 | 1988篇 |
2013年 | 2601篇 |
2012年 | 2050篇 |
2011年 | 2713篇 |
2010年 | 2276篇 |
2009年 | 1635篇 |
2008年 | 1413篇 |
2007年 | 1319篇 |
2006年 | 1192篇 |
2005年 | 985篇 |
2004年 | 815篇 |
2003年 | 741篇 |
2002年 | 662篇 |
2001年 | 603篇 |
2000年 | 448篇 |
1999年 | 354篇 |
1998年 | 245篇 |
1997年 | 254篇 |
1996年 | 191篇 |
1995年 | 157篇 |
1994年 | 175篇 |
1993年 | 146篇 |
1992年 | 129篇 |
1991年 | 115篇 |
1990年 | 105篇 |
1989年 | 78篇 |
1988年 | 79篇 |
1987年 | 75篇 |
1985年 | 1237篇 |
1984年 | 2063篇 |
1983年 | 1349篇 |
1982年 | 1468篇 |
1981年 | 1416篇 |
1980年 | 1217篇 |
1979年 | 1105篇 |
1978年 | 999篇 |
1977年 | 862篇 |
1976年 | 1023篇 |
1975年 | 805篇 |
1974年 | 745篇 |
1973年 | 754篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Edwin van der Pol Joshua A. Welsh Rienk Nieuwland 《Journal of thrombosis and haemostasis》2022,20(1):245-251
The Extracellular Vesicle Flow Cytometry Working Group ( http://www.evflowcytometry.org ) is formed by members of the International Society for Extracellular Vesicles (ISEV), the International Society for Advancement of Cytometry (ISAC), and the International Society on Thrombosis and Haemostasis (ISTH). This working group of flow cytometry experts develops guidelines for best practices regarding flow cytometry detection of extracellular vesicles. To improve rigor and standardization, this working group published a framework outlining the minimal information to report about a flow cytometry experiment on extracellular vesicles (MIFlowCyt-EV) in the Journal of Extracellular Vesicles, the ISEV journal, in 2020. In parallel, an article explaining MIFlowCyt-EV was published in Cytometry Part A, one of the ISAC journals, and now will be introduced to the ISTH as an SSC Communication in the Journal of Thrombosis and Haemostasis. The goal of this SSC Communication is to explain why flow cytometry is becoming the instrument of choice to characterize single extracellular vesicles, the obstacles that have been identified and (mostly) overcome by developing procedures to calibrate flow cytometers, and the relevance of reporting minimal information to improve reliability and reproducibility of experiments in which flow cytometers are used for characterization of extracellular vesicles. 相似文献
2.
3.
《Journal of the American Medical Directors Association》2022,23(3):379-386.e3
ObjectivesPreclinical and clinical studies indicate a role for MLC901 (NeuroAiD II) in Alzheimer's disease (AD). The primary aim was to investigate its safety as add-on therapy to standard treatment and the secondary aims its effect on cognition and slowing disease progression.DesignRandomized double-blind placebo-controlled delayed-start study.Setting and ParticipantPatients with mild to moderate probable AD by NINCDS-ADRDA criteria, stable on acetylcholinesterase inhibitors or memantine (n = 125), were randomized to receive MLC901 (early starters) or placebo (delayed starters) for 6 months, followed by a further 6 months when all patients received MLC901, in a delayed-start design (clinical trial registration: ClinicalTrials.gov, NCT03038035).MethodsThe primary outcome measure was occurrence of serious adverse events (SAEs) at 6 months. Secondary outcomes included the Alzheimer's Disease Assessment Scale–Cognitive subscale (ADAS-Cog) and other assessment scales.ResultsThere was no significant difference in the risk of SAEs between early and delayed starters at month (M) 6 (22.6% vs 27.0%, risk difference ?4.4%, 90% CI –16.9% to 8.3%). Similarly, there was no significant difference in the risk of adverse events and the occurrence of stroke or vascular events between early and delayed starters throughout the 12-month study period. Early starters did not differ significantly on ADAS-Cog from delayed starters at M6 [mean difference (MD) ?1.0, 95% CI –3.3 to 1.3] and M12 (MD –2.35, 95% CI –5.45 to 0.74) on intention-to-treat analysis. Other cognitive assessment scales did not show significant differences.Conclusions and ImplicationsThis study of 125 persons with dementia found no evidence of a significant increase in adverse events between MLC901 and placebo, thus providing support for further studies on both efficacy and safety. Analyses suggest the potential of MLC901 in slowing down AD progression, but this requires further confirmation in larger and longer studies using biomarkers for AD. 相似文献
4.
《Clinical breast cancer》2022,22(6):507-514
Breast cancer (BC) is a highly metastatic, pathological cancer that significantly affects women worldwide. The mortality rate of BC is related to its heterogeneity, aggressive phenotype, and metastasis. Recent studies have highlighted that the tumor microenvironment (TME) is critical for the interplay between metastasis mediators in BC. BC stem cells, tumor-derived exosomes, circulatory tumor cells (CTCs), and signaling pathways dynamically remodel the TME and promote metastasis. This review examines the cellular and molecular mechanisms governing the epithelial to mesenchymal transition (EMT) that facilitate metastasis. This review also discusses the role of cancer stem cells (CSCs), tumor-derived exosomes, and CTs in promoting BC metastasis. Furthermore, the review emphasizes major signaling pathways that mediate metastasis in BC. Finally, the interplay among CSCs, exosomes, and CTCs in mediating metastasis have been highlighted. Therefore, understanding the molecular cues that mediate the association of CSCs, exosomes, and CTCs in TME helps to optimize systemic therapy to target metastatic BC. 相似文献
5.
目的 银椴苷(Tiliroside,Tle)是一种天然产物,存在于结香花(Edgeworthia chrysantha Lindl.)、金英(Galphimia gracilis)、和Phlomoides spectabilis等生物体中。本文主要探讨Tle对脂多糖(lipopolysaccharide,LPS)激活的原代小胶质细胞的M1/M2极化的转化作用及其抑制神经炎症反应的影响。方法 MTT检测各浓度Tle对LPS激活的原代小胶质细胞活性的影响;Griess试剂检测LPS激活的原代小胶质细胞的一氧化氮(Nitric oxide,NO)产物生成量的影响;ELISA法检测Tle对LPS激活的原代小胶质细胞的肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)、白细胞介素-6(Interleukin-6,IL-6)蛋白水平的影响;qRT-PCR检测Tle对LPS激活的原代小胶质细胞的精氨酸酶-1(Arginase-1,Arg-1)和胰岛素生长因子-1(Insulin growth factor-1,IGF-1)的mRNA表达水平。结果 Tle(0-80 μmol·L-1)对LPS激活的原代小胶质细胞活性没有明显影响;Tle显著降低LPS激活的原代小胶质细胞亚硝酸盐的含量,并对炎症因子IL-6、TNF-α蛋白水平有显著抑制作用,同时显著提高抗炎因子Arg-1和IGF-1的mRNA水平。结论 Tle能够通过促进LPS激活的原代小胶质细胞M1型向M2型转化从而抑制神经炎症反应,因此Tle具有一定的神经保护作用。 相似文献
6.
《Clinical neurophysiology》2021,132(9):2003-2011
ObjectiveA large N20 and P25 of the median nerve somatosensory evoked potential (SEP) predicts short survival in amyotrophic lateral sclerosis (ALS). We investigated whether high frequency oscillations (HFOs) over N20 are enlarged and associated with survival in ALS.MethodsA total of 145 patients with ALS and 57 healthy subjects were studied. We recorded the median nerve SEP and measured the onset-to-peak amplitude of N20 (N20o-p), and peak-to-peak amplitude between N20 and P25 (N20p-P25p). We obtained early and late HFO potentials by filtering SEP between 500 and 1 kHz, and measured the peak-to-peak amplitude. We followed up patients until endpoints (death or tracheostomy) and analyzed the relationship between SEP or HFO amplitudes and survival using a Cox analysis.ResultsPatients showed larger N20o-p, N20p-P25p, and early and late HFO amplitudes than the control values. N20p-P25p was associated with survival periods (p = 0.0004), while early and late HFO amplitudes showed no significant association with survival (p = 0.4307, and p = 0.6858, respectively).ConclusionsThe HFO amplitude in ALS is increased, but does not predict survival.SignificanceThe enlarged HFOs in ALS might be a compensatory phenomenon to the hyperexcitability of the sensory cortex pyramidal neurons. 相似文献
7.
《Clinical neurophysiology》2021,132(10):2357-2364
ObjectivesTo investigate the subcortical somatosensory evoked potentials (SEPs) to electrical stimulation of either muscle or cutaneous afferents.MethodsSEPs were recorded in 6 patients suffering from Parkinson’s disease (PD) who underwent electrode implantation in the pedunculopontine (PPTg) nucleus area. We compared SEPs recorded from the scalp and from the intracranial electrode contacts to electrical stimuli applied to: 1) median nerve at the wrist, 2) abductor pollicis brevis motor point, and 3) distal phalanx of the thumb. Also the high-frequency oscillations (HFOs) were analysed.ResultsAfter median nerve and pure cutaneous (distant phalanx of the thumb) stimulation, a P1-N1 complex was recorded by the intracranial lead, while the scalp electrodes recorded the short-latency far-field responses (P14 and N18). On the contrary, motor point stimulation did not evoke any low-frequency component in the PPTg traces, nor the N18 potential on the scalp. HFOs were recorded to stimulation of all modalities by the PPTg electrode contacts.ConclusionsStimulus processing within the cuneate nucleus depends on modality, since only the cutaneous input activates the complex intranuclear network possibly generating the scalp N18 potential.SignificanceOur results shed light on the subcortical processing of the somatosensory input of different modalities. 相似文献
8.
Kari Gire Dahl Astrid Klopstad Wahl Kristin Hjorthaug Urstad Ragnhild S. Falk Marit Helen Andersen 《Patient education and counseling》2021,104(7):1814-1822
ObjectivesThe study aimed to identify changes in health literacy (HL) and associated variables during the first year following a kidney transplantation.MethodsA total of 196 transplant recipients were included in a prospective follow-up study. The patients answered the Health Literacy Questionnaire (HLQ) at 5 days, 8 weeks, 6 and 12 months following the kidney transplantation. Mixed linear models were used to analyze changes in HL and backward elimination was used to identify variables associated with HL.ResultsTwo main patterns of change were identified: a) HL increased during the first 8 weeks of close follow-up and b) in several domains, the positive increase from 5 days to 8 weeks flattened out from 5 days to 6 and 12 months. Self-efficacy, transplant-related knowledge, and general health were core variables associated with HL.ConclusionsOverall, HL increased during the 8 weeks of close follow-up following the kidney transplantation, while 6 months seem to be a more vulnerable phase. Furthermore, low self-efficacy, less knowledge, and low self-perceived health may represent vulnerable characteristics in patients.Practical implicationsFuture kidney transplant care should take into account patients’ access to and appraisal of health information and social support, and draw attention to potentially vulnerable groups. 相似文献
9.
10.
《Clinical neurophysiology》2021,132(2):315-322
ObjectivePrevious studies have demonstrated voluntary movement alterations as well as motor cortex excitability and plasticity changes in patients with mild cognitive impairment (MCI). To investigate the pathophysiology of movement abnormalities in MCI, we tested possible relationships between movement abnormalities and primary motor cortex alterations in patients.MethodsFourteen amnestic MCI (aMCI) patients and 16 healthy controls were studied. Cognitive assessment was performed using clinical scales. Finger tapping was recorded by a motion analysis system. Transcranial magnetic stimulation was used to test the input/output curve of motor evoked potentials, intracortical inhibition, and short-latency afferent inhibition. Primary motor cortex plasticity was probed by theta burst stimulation. We investigated correlations between movement abnormalities, clinical scores, and cortical neurophysiological parameters.ResultsMCI patients showed less rhythmic movement but no other movement abnormalities. Cortical excitability measures were normal in patients, whereas plasticity was reduced. Movement rhythm abnormalities correlated with frontal dysfunction scores.ConclusionOur study in MCI patients demonstrated abnormal voluntary movement and plasticity changes, with no correlation between the two. Altered rhythm correlated with frontal dysfunction.SignificanceOur results contribute to the understanding of pathophysiological mechanisms of motor impairment in MCI. 相似文献