首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   297篇
  免费   18篇
  国内免费   10篇
  2023年   6篇
  2022年   13篇
  2021年   15篇
  2020年   15篇
  2019年   10篇
  2018年   15篇
  2017年   11篇
  2016年   12篇
  2015年   13篇
  2014年   22篇
  2013年   41篇
  2012年   9篇
  2011年   15篇
  2010年   12篇
  2009年   18篇
  2008年   13篇
  2007年   8篇
  2006年   16篇
  2005年   11篇
  2004年   7篇
  2003年   11篇
  2002年   5篇
  2001年   3篇
  1999年   2篇
  1998年   1篇
  1996年   3篇
  1995年   1篇
  1994年   3篇
  1993年   4篇
  1992年   1篇
  1991年   1篇
  1990年   3篇
  1989年   2篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
排序方式: 共有325条查询结果,搜索用时 406 毫秒
91.
以本实验室建立的CSFV39-PKl5持续感染细胞模型为实验材料,综合运用免疫荧光、RT-PCR、流式细胞仪,对其稳定性进行研究。实验结果均表明,该细胞模型有着良好的稳定性。即使在连续传至128代的CSFV39-PKl5传代细胞中,CSFV仍持续存在:呈免疫荧光抗体反应阳性和RT-PCR检测阳性。同时,该细胞与正常的PK-15细胞相比,细胞周期无显著差异。通过同段序列的同源性比较,发现CSFV39与CSFV石门株的同源性最高,达99.02%。  相似文献   
92.
The influence of psychosocial components on back and abdominal endurance tests in patients with persistent non-specific low back pain should be investigated to ensure the correct interpretation of these measures. Three-hundred and thirty-two patients (291 men and 41 women) from 19 to 63 years performed an abdominal and back muscle endurance test after completing some psychosocial questionnaires. During the endurance tests, surface electromyography signals of the internal obliques, the external obliques, the lumbar multifidus and the iliocostalis were recorded. Patients were dichotomized as underperformers and good performers, by comparing their real endurance time, to the expected time of endurance derived from the normalized median frequency slope. Independent t-tests were performed to examine the differences on the outcome of the questionnaires. In the back muscle endurance test, the underperformers had significantly lower (p < 0.05) scores on some of the physical subscales of the SF-36. The underperformers group of the AE test scored significantly higher on the DRAM MZDI (p = 0.018) and on the PCS scale (p = 0.020) and showed also significantly lower scores on the SF-36 (p < 0.05). Back muscle endurance tests are influenced by physical components, while abdominal endurance tests seem influenced by psychosocial components.  相似文献   
93.
94.
Traditional models of insect vision have assumed that insects are only capable of low-level analysis of local cues and are incapable of global, holistic perception. However, recent studies on honeybee (Apis mellifera) vision have refuted this view by showing that this insect also processes complex visual information by using spatial configurations or relational rules. In the light of these findings, we asked whether bees prioritize global configurations or local cues by setting these two levels of image analysis in competition. We trained individual free-flying honeybees to discriminate hierarchical visual stimuli within a Y-maze and tested bees with novel stimuli in which local and/or global cues were manipulated. We demonstrate that even when local information is accessible, bees prefer global information, thus relying mainly on the object''s spatial configuration rather than on elemental, local information. This preference can be reversed if bees are pre-trained to discriminate isolated local cues. In this case, bees prefer the hierarchical stimuli with the local elements previously primed even if they build an incorrect global configuration. Pre-training with local cues induces a generic attentional bias towards any local elements as local information is prioritized in the test, even if the local cues used in the test are different from the pre-trained ones. Our results thus underline the plasticity of visual processing in insects and provide new insights for the comparative analysis of visual recognition in humans and animals.  相似文献   
95.

Background

Recent evidence questions the role of intra-aortic balloon counterpulsation (IABP) in the treatment of acute myocardial infarction (AMI) complicated by cardiogenic shock (CS). An area of increasing interest is the use of IABP for persistent ischaemia (PI). We analysed the use of IABP in patients with AMI complicated by CS or PI.

Methods

From 2008 to 2010, a total of 4076 patients were admitted to our hospital for primary percutaneous coronary intervention (PCI) for AMI. Out of those, 239 patients received an IABP either because of CS or because of PI. Characteristics and outcome of those patients are investigated.

Results

The mean age of the study population was 64 ± 11 years; 75 % were male patients. Of the patients, 63 % had CS and 37 % had PI. Patients with CS had a 30-day mortality rate of 36 %; 1-year mortality was 41 %. Patients with PI had a 30-day mortality rate of 7 %; 1-year mortality was 11 %.

Conclusions

Mortality in patients admitted for primary PCI because of AMI complicated by CS is high despite IABP use. Outcome in patients treated with IABP for PI is favourable and mandates further prospective studies.  相似文献   
96.
Neurexins are cell adhesion proteins that interact with neuroligin and other ligands at the synapse. In humans, mutations in neurexin or neuroligin genes have been associated with autism and other mental disorders. The human neurexin and neuroligin genes are orthologous to the Caenorhabditis elegans genes nrx‐1 and nlg‐1, respectively. Here we show that nrx‐1‐deficient mutants are defective in exploratory capacity, sinusoidal postural movements and gentle touch response. Interestingly, the exploratory behavioral phenotype observed in nrx‐1 mutants was markedly different to nlg‐1‐deficient mutants; thus, while the former had a ‘hyper‐reversal’ phenotype increasing the number of changes of direction with respect to the wild‐type strain, the nlg‐1 mutants presented a ‘hypo‐reversal’ phenotype. On the other hand, the nrx‐1‐ and nlg‐1‐defective mutants showed similar abnormal sinusoidal postural movement phenotypes. The response of these mutant strains to aldicarb (acetylcholinesterase inhibitor), levamisole (ACh agonist) and pentylenetetrazole [gamma‐aminobutyric (GABA) receptor antagonist], suggested that the varying behavioral phenotypes were caused by defects in ACh and/or GABA inputs. The defective behavioral phenotypes of nrx‐1‐deficient mutants were rescued in transgenic strains expressing either human alpha‐ or beta‐NRXN‐1 isoforms under the worm nrx‐1 promoter. A previous report had shown that human and rat neuroligins were functional in C. elegans. Together, these results suggest that the functional mechanism underpinning both neuroligin and neurexin in the nematode are comparable to human. In this sense the nematode might constitute a simple in vivo model for understanding basic mechanisms involved in neurological diseases for which neuroligin and neurexin are implicated in having a role.  相似文献   
97.
Data mining techniques are highly useful in the study of various medical signals and images in order to obtain useful information to better predict the diagnosis or prognosis or treatment options for the patient. Study of the human walking pattern helps us understand the variability of motion during activities such as high performance walking and normal walking. A comparison of the parameters quantifying this variability in motion in normal young and elderly subjects and the subjects who need support will aid in better understanding of the relationship among walking patterns, age and disabilities. In this study, we measured the tri-axial acceleration along three directions: anteroposterior, lateral and vertical. We also measured gyrational pitch, roll and yaw. These parameters were obtained using sensors attached to the back, left thigh and right thigh of the three classes of subjects (normal, elderly and adults with support) during the three types of exercises: 10-m normal walk, 10-m high performance walk and stepping. These recorded signals were then subjected to wavelet packet decomposition, and three entropies, namely approximate entropy and two bispectral entropies, were obtained from the resultant wavelet coefficients. On analysing these entropies, we could observe the following: (1) the entropy steadily decreases with the increase in age and with the presence of impairments, and (2) the entropy decreases among all the three types of exercises, namely normal walking and high performance walking. We feel that the results of this work can help in the design of supporting devices for elderly subjects.  相似文献   
98.
99.
Catheter ablation for atrioventricular nodal re-entrant tachycardia (AVNRT) in patients with persistent left superior vena cava (PLSVC) is challenging because of anatomical abnormalities of Koch's triangle associated with the enlarged coronary sinus ostium. We present the Case of successful ablation in a patient with PLSVC using the cryoablation technique. The ablation was successfully performed without damaging the conduction system by virtue of “cryomapping” and “cryoadhesion.” Cryoablation is a safe and efficacious alternative to radiofrequency catheter ablation for the treatment of AVNRT associated with PLSVC.  相似文献   
100.
摘要 目的:探讨小醒脑针刺法联合度洛西汀对持续性姿势-知觉性头晕(PPPD)患者心理状态、睡眠质量及平衡功能的影响。方法:收集2017年1月~2019年6月期间我院收治的70例PPPD患者为研究对象。按门诊号单双数将研究对象分为对照组(n=35,度洛西汀治疗)和研究组(n=35,小醒脑针刺法联合度洛西汀治疗),对比两组头晕发作频次、头晕发作持续时间以及眩晕残障程度评定量表(DHI)评分、汉密尔顿抑郁量表(HAMD)评分、汉密尔顿焦虑量表(HAMA)评分、Berg平衡量表(BBS)评分、活动平衡信心量表(ABC)评分、微觉醒指数、入睡后清醒时间、睡眠分期转换次数、醒转次数、匹兹堡睡眠质量指数(PSQI)评分。结果:两组治疗后头晕发作频次、头晕发作持续时间、微觉醒指数、入睡后清醒时间、睡眠分期转换次数、醒转次数以及DHI、PSQI、HAMA、HAMD评分均较治疗前降低,且研究组较对照组低(P<0.05)。治疗后两组BBS、ABC评分均较治疗前升高,且研究组较对照组高(P<0.05)。结论:小醒脑针刺法联合度洛西汀治疗PPPD患者,可有效改善患者眩晕症状、心理状态、睡眠质量及平衡功能。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号