全文获取类型
收费全文 | 3614篇 |
免费 | 187篇 |
国内免费 | 81篇 |
专业分类
耳鼻咽喉 | 71篇 |
儿科学 | 55篇 |
妇产科学 | 32篇 |
基础医学 | 791篇 |
口腔科学 | 51篇 |
临床医学 | 469篇 |
内科学 | 438篇 |
皮肤病学 | 17篇 |
神经病学 | 412篇 |
特种医学 | 88篇 |
外科学 | 397篇 |
综合类 | 453篇 |
现状与发展 | 1篇 |
预防医学 | 130篇 |
眼科学 | 33篇 |
药学 | 191篇 |
1篇 | |
中国医学 | 221篇 |
肿瘤学 | 31篇 |
出版年
2023年 | 36篇 |
2022年 | 56篇 |
2021年 | 96篇 |
2020年 | 114篇 |
2019年 | 64篇 |
2018年 | 85篇 |
2017年 | 70篇 |
2016年 | 89篇 |
2015年 | 71篇 |
2014年 | 174篇 |
2013年 | 164篇 |
2012年 | 131篇 |
2011年 | 173篇 |
2010年 | 145篇 |
2009年 | 182篇 |
2008年 | 170篇 |
2007年 | 168篇 |
2006年 | 153篇 |
2005年 | 157篇 |
2004年 | 115篇 |
2003年 | 123篇 |
2002年 | 113篇 |
2001年 | 117篇 |
2000年 | 106篇 |
1999年 | 102篇 |
1998年 | 131篇 |
1997年 | 109篇 |
1996年 | 92篇 |
1995年 | 100篇 |
1994年 | 97篇 |
1993年 | 52篇 |
1992年 | 51篇 |
1991年 | 43篇 |
1990年 | 25篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 28篇 |
1986年 | 15篇 |
1985年 | 19篇 |
1984年 | 14篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1974年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有3882条查询结果,搜索用时 15 毫秒
1.
《Neuro-Chirurgie》2022,68(4):414-425
Intraoperative monitoring of cerebral blood flow (CBF) has become an invaluable adjunct to vascular and oncological neurosurgery, reducing the risk of postoperative morbidity and mortality. Several technologies have been developed during the last two decades, including laser-based techniques, videomicroscopy, intraoperative MRI, indocyanine green angiography, and thermography. Although these technologies have been thoroughly studied and clinically applied outside the operative room, current practice lacks an optimal technology that perfectly fits the workflow within the neurosurgical operative room. The different available technologies have specific strengths but suffer several drawbacks, mainly including limited spatial and/or temporal resolution. An optimal CBF monitoring technology should meet particular criteria for intraoperative use: excellent spatial and temporal resolution, integration in the operative workflow, real-time quantitative monitoring, ease of use, and non-contact technique. We here review the main contemporary technologies for intraoperative CBF monitoring and their current and potential future applications in neurosurgery. 相似文献
2.
3.
目的明确高呼气末正压(PEEP)条件下肺泡微循环的变化情况以及液体复苏在高PEEP情况下对肺泡微循环的影响。
方法选用北京当地的15条健康成年杂种狗进行实验,分别观察基线(PEEP 5 cmH2O,1 cmH2O=0.098 kPa)、高PEEP(平均动脉压下降≥20 mmHg,1 mmHg=0.133 kPa)及液体复苏后的呼吸、系统循环及肺泡微循环情况,肺泡微循环利用旁流暗视野成像(SDF)技术进行观察、留取视频结果,线下利用AVA3.2软件进行分析,不同条件下的实验数据之间的差异利用Wilcoxon秩和检验进行分析。
结果高PEEP可导致中心静脉压(CVP)升高(P=0.001)及心输出量(CO)下降(P=0.002),肺泡微循环表现为总微血管数量(TVDa,P=0.036)、灌注血管数量(PVDa,P=0.002)、灌注血管比例(PPVa,P=0.003)、血流状态(MFIa,P=0.002)显著下降,肺泡周围毛细血管密度下降不明显(TVDs,P=0.319);液体复苏恢复整体循环后,微循环参数均无显著改善。
结论过高的PEEP水平可导致肺泡微循环的显著恶化,通过液体复苏不能改善由此产生的微循环障碍。 相似文献
4.
Fang Xing Xin Fang Xiang-Dan Gong Xin Zhao Ying Du Zheng-Liang Ma Xiao-Ping Gu Tian-Jiao Xia 《中国神经再生研究》2020,(6):1094-1101
Sleep-wake rhythm disturbances,which are characterized by abnormal sleep timing or duration,are associated with cognitive dysfunction.Photoacoustic treatments including light and sound stimulation have been found to be effective in modulating sleep patterns and improving cognitive behavior in abnormal sleep-wake pattern experiments.In this study,we examined whether light and sound interventions could reduce sleep-wake pattern disturbances and memory deficits in a sleep rhythm disturbance model.We established a model of sleep rhythm disturbance in C57 BL/6 J mice via a sleep deprivation method involving manual cage tapping,cage jostling,and nest disturbance.We used a Mini Mitter radio transmitter device to monitor motor activity in the mice and fear conditioning tests to assess cognitive function.Our results indicated that an intervention in which the mice were exposed to blue light(40-Hz flickering frequency)for 1 hour during their subjective daytime significantly improved the 24-hour-acrophase shift and reduced the degree of memory deficit induced by sleep deprivation.However,interventions in which the mice were exposed to a 40-Hz blue light at offset time or subjective night time points,as well as 2 Hz-blue light at 3 intervention time points(subjective day time,subjective night time,and offset time points),had no positive effects on circadian rhythm shift or memory deficits.Additionally,a 2000-Hz sound intervention during subjective day time attenuated the24-hour-acrophase shift and memory decline,while 440-Hz and 4000-Hz sounds had no effect on circadian rhythms.Overall,these results demonstrate that photoacoustic treatment effectively corrected abnormal sleep-wake patterns and cognitive dysfunction associated with sleep-deprivation-induced disturbances in sleep-wake rhythm.All animal experiments were approved by the Experimental Animal Ethics Committee of Drum Tower Hospital Affiliated to the Medical College of Nanjing University,China(approval No.20171102)on November20,2017. 相似文献
5.
《Sleep medicine》2020
BackgroundTo date, no previous studies have evaluated the relationship between sleep duration and quality of life (QOL) or depression in the general population after controlling for daytime sleepiness and sleep disturbances.MethodsA web-based cross-sectional survey was conducted with 8698 subjects aged 20–69 years. We examined the relationships between weekday sleep duration and daytime sleepiness, sleep disturbance, QOL and depression, using the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index (without the item for sleep duration), 8-item Short Form and Center for Epidemiological Studies Depression Scale (CES-D).ResultsDaytime sleepiness tended to increase in proportion to shorter weekday sleep durations. Sleep disturbances, physical and mental QOL, and CES-D scores were worse in both the shorter and longer sleep groups compared with the group with 7–8 h of sleep. Hierarchical logistic regression analyses revealed that short sleep duration but not long sleep duration was significantly associated with reduction of both physical and mental QOL, even after controlling for the presence of daytime sleepiness and sleep disturbance. Both short and long sleep duration were independently and significantly correlated with depression after controlling for daytime sleepiness; however, there was no statistically significant association after adjusting for the effects of sleep disturbance.ConclusionsThe results suggested adverse effects of short sleep but not long sleep on both physical and mental QOL. In addition, the negative impact of specific types of sleep disturbance on depression may be greater than the impact of shortening of sleep duration. 相似文献
6.
7.
《Sleep medicine》2020
Study objectivesTo analyze the association between sleep-related symptoms and sleep length in parents and their children in relation to other risk factors in both generations.MethodThe participants were parents (n = 5,855, age 54.3 ± 6.5 years, 45.2% men) who participated in the community-based Respiratory Health in Northern Europe (RHINE) study and one random member of their adult offspring (n = 5,855, age 30.2 ± 7.7 years, 41.5% men) who participated in the Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) study. Both generations responded to identical questionnaires on sleep symptoms, including difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), early morning awakening (EMA), snoring, nocturnal sweating, nocturnal gastroesophageal reflux (nGER), sleep time and excessive daytime sleepiness (EDS). Insomnia was defined as either, or both, DIS and DMS in combination with EDS.ResultsAll sleep variables except nocturnal sweating were more common in offspring whose parents had reported the same symptom. After adjusting for age, gender, BMI, smoking, physical activity, education, center and parents' total number of children, there were independent associations between sleep symptoms in parents and offspring for DIS (adj. OR, 95% CI: 1.52, 1.20–1.93), DMS (1.34, 1.15–1.56), snoring (1.45, 1.15,1.83), nGER (1.65, 1.15–2.37), insomnia (1.39, 1.13–1.73), short sleep time (<6 h/night) (2.51, 1.72–3.68) and EDS (1.48, 1.26,1.72). There were no independent relationships between symptoms in parents and offspring for EMA, nocturnal sweating or long sleep time (>9 h/night).ConclusionThe familiar aggregation of many sleep disturbances was not explained by investigated lifestyle and environmental factors. This supports a heritable factor in sleep problems. 相似文献
8.
甲襞微循环监测在嗜铬细胞瘤术前准备中的应用 总被引:2,自引:0,他引:2
目的:探讨甲襞微循环监测在嗜铬细胞瘤术前药物准备中的临床意义。方法:采取前瞻性自身对照研究,对20例嗜铬细胞瘤患者术前用竹林胺药物准备前、后,以及术后2~3个月,通过WXT-4型微循环图象计算机分析系统监测甲襞微循环,在微循环形态、血管流态、血管周围的情况三方面共22项指标进行定量分析与t检验。结果:20例患者经药物准备前后,在血管襻清晰度、管襻数、输入支管径、输出支管径、管襻长度、红细胞聚集程度、血色、形态积分、流态积分、总积分这10项微循环指标的统计学检验显示差异均有统计学意义(P<0.05或P>0.01);而手术前后微循环各项指标间差异无统计学意义。结论:甲襞微循环可以较好地反映全身微循环的状况,甲襞微循环监测可作为嗜铬细胞瘤术前准备的一项重要指标应用于临床。 相似文献
9.
目的 :探讨遏制急性胰腺炎向重症转化的非手术治疗策略。方法 :将4年间收治的286例轻型急性胰腺炎分为对照组和治疗观察组。对照组采取常规非手术治疗措施;观察组加用改善胰腺微循环,防治细胞钙超载和抑制胰酶的治疗方法。结果 :对照组144轻型有20例转化为重症胰腺炎,14例发生全身性并发症;观察组142例轻型有8例转化为重症,2例出现全身性并发症。观察组重症患者血C-反应蛋白和Balthazar CT严重度指数在治疗后各时点较对照组明显降低。结论 :在常规治疗的基础上加用改善胰腺微循环,防治细胞钙超载和抑制胰酶的治疗措施可能有助于阻止轻型急性胰腺炎向重症化发展。 相似文献
10.
内脏器官激光多谱勒血流灌注图象的显示 总被引:5,自引:0,他引:5
目的显示内脏器官血流灌注和分布的图象,探讨激光多谱勒血流成像技术在内脏微循环检测中的价值。方法应用激光多谱勒血流灌注成像仪(LDPI),对大鼠和家兔腹部脏器(肝、脾、肾、膀胱、胃、大小肠和肠系膜等)的血流灌注进行扫描和血流图显示。结果在体内脏器官显像清晰,肝、肾、脾、膀胱等微循环血流的整体分布较均匀;而胃、肠系膜、回盲肠等激光多谱勒血流图上大血流线状显示极其显著;大鼠与家兔两种动物之间相同脏器血流图上的差异并不明显。结论LDPI能将内脏器官的微循环状态以图象的形式显示,该新技术方法在检测内脏血流方面将有一定的应用价值。 相似文献