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   207篇
  免费   8篇
  国内免费   2篇
教育   158篇
科学研究   15篇
体育   29篇
综合类   13篇
信息传播   2篇
  2022年   6篇
  2021年   3篇
  2020年   1篇
  2019年   7篇
  2018年   5篇
  2017年   6篇
  2016年   4篇
  2015年   2篇
  2014年   13篇
  2013年   17篇
  2012年   15篇
  2011年   14篇
  2010年   11篇
  2009年   10篇
  2008年   7篇
  2007年   25篇
  2006年   10篇
  2005年   11篇
  2004年   12篇
  2003年   8篇
  2002年   8篇
  2001年   9篇
  2000年   2篇
  1999年   2篇
  1998年   3篇
  1996年   3篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
排序方式: 共有217条查询结果,搜索用时 15 毫秒
141.
Best-practice guidelines have incorporated ultrasound in diagnostic and procedural medicine. Due to this demand, the Arizona College of Osteopathic Medicine initiated a comprehensive integration of ultrasound into its first-year anatomy course attended by more than 280 students. Ultrasound workshops were developed to enhance student conceptualization of musculoskeletal (MSK) anatomy through visualizing clinically important anatomical relationships, a simulated lumbar puncture during the back unit, carpal tunnel and shoulder evaluations during the upper limb unit, and plantar fascia, calcaneal tendon, and tarsal tunnel evaluations during the lower limb unit. A 5-point Likert scale survey evaluated if ultrasound improved students' self-perceived anatomical and clinical comprehension of relevant anatomy, improved students' ability to orient to ultrasound imagery, and prompted further independent investigation of the anatomical area. Ultrasound examination questions were added to the anatomy examinations. Two-tailed one-sample t-tests for the back, upper limb, and lower limb units were found to be significant across all Likert survey categories (P < 0.001). Positive student responses to the Likert survey in conjunction with examination question average of 84.3% (±10.3) demonstrated that the ultrasound workshops are beneficial to student education. Ultrasound enhances medical students' clinical and anatomical comprehension and ability to orient to ultrasound imagery for MSK anatomy. This study supports early ultrasound education as a mechanism to encourage students' independent learning as evidenced by many undertaking voluntary investigation of clinical concerns associated with MSK anatomy. This study establishes the successful integration of MSK ultrasound into a large medical school program and its benefit to student clinical education.  相似文献   
142.
目的:利用经颅多普勒超声技术(TCD)得到的搏动指数(PI),分析其与颅内小血管疾病局部血流动力学诊断指标之间的相关性,探讨轻度认知障碍(MCI)患者的相关因素,为MCI的早期诊断提供更好的依据。方法:通过对某社区参与老龄化研究,选取其中符合轻度认知障碍诊断标准205名老年居民进行经颅多普勒和磁共振成像检查。分析大脑中动脉搏动指数(MCA PI)与脑白质病变(WML)、腔隙性脑梗及脑内微出血等疾病的诊断指标之间的关系。结果:Logistic多元回归分析发现,大脑中动脉搏动指数(MCA PI)与重度脑白质病变(WML)相关,比值比(OR值)1.33,95%置信区间1.04~1.70,P=0.02。在最优截止MCA PI处,曲线下方面积为0.70(95%置信区间0.60~0.80),重度WML的阳性预测值和阴性预测值分别为34.9%和85.6%。大脑动脉搏动指数(MCA PI)与腔隙性脑梗、脑内微出血等疾病的诊断指标之间没有相关性。结论:大脑中动脉搏动指数(PI)与MCI有一定相关性。经颅多普勒超声能为社区中进行选择性磁共振成像扫描检测WML提供指导。  相似文献   
143.
从带教难点、具体带教方法、带教考评体系和带教注意事项等方面总结中山大学附属第三医院超声科产前超声诊断教学中积累的经验,期望在今后的实习生、进修生带教中取得更好的教学效果。  相似文献   
144.
通过对举重运动员和无训练一般正常青年人的超声心动图(U·C·G)的分析,探讨长期从事举重训练对运动员左心形态和功能的影响,同时尝试对其机理加以探讨。  相似文献   
145.
超声图像广泛应用于工业,海洋,医学等领域并且在诸多领域起到不可替代的重要作用。但大规模乘性噪声严重影响了超声图像的成像质量。无法精准判读超声图像,制约着超声图像应用的发展。为此,提出超声图像大规模乘性噪声干扰的过滤算法,通过对超声图像成像像素进行像块分解重组重构出大规模乘性噪声部分,运用滤波函数公式提取出大规模乘性噪声干扰量,建立超声图像大规模乘性噪声过滤模型将乘性噪声干扰进行过滤计算,重构更为清晰的超声图像的过程。仿真实验证明,超声图像大规模乘性噪声干扰过滤算法有效的抑制了大规模乘性噪声对图像质量的影响,更好的保留了超声图像的细节信息。  相似文献   
146.
超声生物效应已经引起人们的广泛关注,如低频超声能够促进生物体细胞的生长和增殖、超声使细胞膜通透性发生改变、超声的热效应能够杀死癌变细胞等。大量研究表明:超声的生物效应与声强、频率、生物细胞内部生长因子、pH值及细胞膜中“电压门”构象密切相关,并且符合声吸收方程:αα=2ωsin[(ωΓlnγ)/2(1+ω^2Γ^2)^1/2]/c.由于生命科学的复杂性与实验手段的局限性,超声对生物体的基因调控、蛋白质表达等复杂问题仍然摆在我们面前.有待于进一步探索与研究。  相似文献   
147.
Effect of high intensity ultrasound on the allergenicity of shrimp   总被引:4,自引:0,他引:4  
The tropomyosin fraction of shrimp proteins is potentially responsible for allergic reaction in individuals with genetic predisposition to allergy. However, there are no efficient and safe methods to reduce its allergenicity. High intensity ultrasound is known to change the structure of proteins. This study is aimed at assessing high intensity ultmsound's effect on the allergenicity of shrimp allergen. Shrimp and purified shrimp allergen were treated with high intensity ultrasound for 30-180 min. Extracts of treated samples were analyzed by enzyme-linked immunosorbent assay (ELISA) with pool serum of shrimp allergy patients and polyclonal anti-allergen antibodies and by immunoblotting after polyacrylamide gel electrophoresis. Shrimp treated with high intensity ultrasound showed a decrease in allergenicity measured with ELISA. A linear relationship between the immune response induced by treated shrimp allergen and the applied treatment time was observed. The decrease in allergenicity was confirmed by immunoblot assays with shrimp allergic patients serum. Allergenicity of shrimp allergen extracted from treated shrimp was higher than that of purified shrimp allergen with the same treatment time. Gel-filtration HPLC was applied for analysis of shrimp allergen after treatment with high intensity ultrasound. Some fractions were appeared with increasing treatment time. The results suggested that high intensity ultrasound could be used to reduce the allergenicity of shrimp.  相似文献   
148.
目的:探讨实时动态四维超声在胎儿畸形产前诊断的应用价值。方法:应用E8、VOLUSON730四维超声对38679例妊娠18~37周胎儿进行常规二维和实时四维超声检查。结果:38679例胎儿中共检出胎儿畸形235例,其中胎儿神经系统畸形65例,颜面部畸形28例,颈部(颈部淋巴水囊瘤)畸形14例,心脏畸形39例,胸部畸形14例,膈疝10例;腹部畸形12例,泌尿系统畸形17例,四肢骨骼畸形36例。结论:四维超声成像较二维超声能提供更丰富的诊断信息,全面直观地显示胎儿畸形,提高了产前诊断胎儿畸形的准确率,具有重要的应用价值。  相似文献   
149.
Decomposition mechanism of chloramphenicol under electron beam irradiation   总被引:1,自引:0,他引:1  
The purpose of this study was to evaluate the potential of electron beam to decompose chloramphenicol (CAP) in aqueous solutions. At the absorbed dose of 15 kGy, the decomposition rate of CAP was 95.24%. The degradation of CAP under electron beam irradiation followed pseudo-first-order kinetics. Redox reactions of CAP aqueous solutions with hydroxyl radicals (.OH), hydrated electrons (eaq) and hydrated atoms (·H) were studied. The increase of the additives would result in the decrease of the degradation efficiency. The concentration of Cl- and NO3- in aqueous solution increased after electron beam irradiation. On the basis of the experimental results, a photocatalytic mechanism was discussed. The rate constant for reactions of .OH and CAP was 9.36×10^7 L/(mol.s) and for reaction of eaq and CAP was 7.33×10^7 L/(mol.s)..OH was supposed to play the key role in the radiation system of aqueous solution. Other free radicals like eaq and .H could also initiate the degradation.  相似文献   
150.
提出一种新型的液体除湿系统——超声雾化液体除湿系统,该系统用超声雾化技术取代了传统塔式除湿过程中的填料,避免了由填料带来的溶液耗量大和阻力大的缺点.建立了数学模型来预测在理想条件下液体除湿过程的效率及耗液量.通过对比计算结果和传统塔式除湿的实验数据,发现后者的溶液耗量远大于理想情况下的耗量.另外,在提出的系统中除湿过程发生在通过超声作用产生的微小除湿剂液滴表面,等量的除湿剂能够产生更大的反应表面积;整个新系统中没有喷嘴和溶液泵,系统阻力和能耗相应降低.因此,该方法比塔式除湿方式更接近于理想情况.  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