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21.
将虚拟仪器技术应用于教学实验是解决实验室仪器设备缺乏和陈旧老化等问题的有效途径。本文利用我院现有的美国NI公司虚拟仪器硬件和LabVIEW软件开发包,通过"基于虚拟仪器技术的纯弯曲梁正应力分布实验"项目的开发,在虚拟仪器技术应用于实验教学方面进行了尝试,取得了一定的成果。  相似文献   
22.
带式输送机液压拉紧装置   总被引:1,自引:0,他引:1  
文章介绍了两种新型的带式输送机拉紧装置,即普通液压传动拉紧装置及压缩空气驱动的液压拉紧装置。压缩空气驱动的液压拉紧装置是以压缩空气为动力源,驱动液压柱塞泵,实现对液压系统供油。  相似文献   
23.
本文作者利用自行研制的激光测氢装置,测量了焊接接头和U型试样中的氢分布,并且推导了U型试样弯曲部分(塑性变形区)的应变、残余应力计算公式。结果表明:在焊接接头中,1.沿熔深方向上,氢分布是不均匀的。最高氢含量在熔合线附近;2.氢的具体分布情况,取决于焊缝金属和母材原始含氢量,以及金相组织。在U型试样中,1.计算应变的公式ε_θ~ρ=(tθ)/(πr_0)和应力公式σ_θ=F((tθ)/(πr_0))~n可以用来计算无明显反弹的U型试样弯曲部分的应变量和残余应力值。1Cr18Ni9Ti(C.R.)钢的F=990MPa、n=0.146;2.氢分布明显受应力和应变的影响。应力、应变值愈大,含氢量愈高。  相似文献   
24.
SSR和ISSR分子标记已广泛应用于研究遗传行为和基因定位。在对水稻早世代稳定遗传特性的研究中,选用分布于水稻12条染色体上的168对多态性较好的SSR引物,对28个稳定株系的F_1、F_2、F_3及同组合的分离株系进行了SSR标记分析;选用26个多态性较好的ISSR引物对5个组合中出现的8个稳定株系及同组合的分离株系进行了ISSR分子标记。结果显示:稳定株系的标记带型出现三种类型:(1)母本带出现,父本带消失;(2)父本带出现,母本带消失;(3)出现非父母标记带型。分离株系表现为杂合标记带。推测水稻早世代稳定是在遗传因子作用下,在杂交受精或合子早期发育中发生了双亲染色体重排,形成纯合的F_1单株。  相似文献   
25.
本通过对金属丝电阻值与压力之间关系进行分析研究,探讨如何利用金属丝受力导致电阻值的变化,实现对压力这一非电物理量的电子测量、转换及在实际中的应用。  相似文献   
26.
通过理论推导,直接利用直角应变花的测量结果做出应变圆,并采用简单的方法解出主应变的大小和方向.  相似文献   
27.
球类活动中踝关节扭伤的防治与功能恢复训练   总被引:1,自引:0,他引:1  
球类运动的特点是人员密集,以抗激烈,加上踝关节的局部稳定性差,易发生扭伤。这不仅会影响学生的体育锻炼,更重要的是会对学生以后的生活造成严重的影响。本文采用文献资料法,实践观察法、问卷调查法和伤者访谈,对在球类活动中,引起学生颗关节损伤的原因及其原理进行了分析,同时提出了踝关节扭伤的治疗方法与功能训练的一些手段。  相似文献   
28.
Strain improvement and medium optimization to increase the productivity of spiramycin were carried out. Of oil tolerant mutant strains screened, one mutant, Streptomyces ambofaciens XC 2-37, produced 9% more spiramycin than the parent strain S. ambofaciens XC 1-29. The effects of soybean oil and propyl alcohol on spiramycin production with S. ambofaciens XC 2-37 were studied. The potency of S. ambofaciens XC 2-37 was improved by 61.8% with addition of 2% soybean oil in the fermentation medium and 0.4% propyl alcohol at 24 hours after incubation. The suitable time for feeding propyl alcohol is at 24 hours after incubation in flask fermentation and at 20 hours after incubation in fermentor fermentation. The new process with S. ambofaciens XC 2-37 was scaled up for industrial scale production of spiramycin in a 60 m3 fermentor in Xinchang Pharmaceutical Factory, Zhejiang Medicine Company, Ltd., China, and the potency and productivity of fermentation were improved by 42.9%.  相似文献   
29.
Strain improvement and medium optimization to increase the productivity of spiramycin were carried out. Of oil tolerant mutant strains screened, one mutant,Streptomyces ambofaciens XC 2–37, produced 9% more spiramycin than the parent strainS. ambofaciens XC 1–29. The effects of soybean oil and propyl alcohol on spiramycin production withS. ambofaciens XC 2–37 were studied. The potency ofS. ambofaciens XC 2–37 was improved by 61.8% with addition of 2% soybean oil in the fermentation medium and 0.4% propyl alcohol at 24 hours after incubation. The suitable time for feeding propyl alcohol is at 24 hours after incubation in flask fermentation and at 20 hours after incubation in fermentor fermentation. The new process withS. ambofaciens XC 2–37 was scaled up for industrial scale production of spiramycin in a 60 m3 fermentor in Xinchang Pharmaceutical Factory, Zhejiang Medicine Company, Ltd., China, and the potency and productivity of fermentation were improved by 42.9%.  相似文献   
30.
Objective: The aim of this study was to investigate subgingival infection frequencies ofPorphyromonas gingivalis and Actinobacillus actinomycetemcomitans strains with genetic variation in Chinese chronic periodontitis (CP) patients and to evaluate its correlation with clinical parameters. Methods: Two multiplex polymerase chain reaction (PCR) assays were developed to detect the 16SrDNA, collagenase (prtC) and fimbria (fimA) genes of P. gingivalis and the 16SrDNA, leukotoxin (lktA) and fimbria-associated protein (fap) genes ofA. actinomycetemcomitans in 60 sulcus samples from 30 periodontal healthy subjects and in 122 subgingival plaque samples from 61 patients with CP. The PCR products were further T-A cloned and sent for nucleotide sequence analysis. Results: The 16SrDNA,prtC andfimA genes ofP. gingivalis were detected in 92.6%, 85.2% and 80.3% of the subgingival plaque samples respectively, while the 16SrDNA, lktA andfap genes ofA. actinomycetemcomitans were in 84.4%, 75.4% and 50.0% respectively. Nucleotide sequence analysis showed 98.62%-100% homology of the PCR products in these genes with the reported sequences. P. gingivalis strains with prtC+/fimA+ and A. actinomycetemcomitans with lktA+ were predominant in deep pockets (〉6 mm) or in sites with attachment loss 〉5 mm than in shallow pockets (3-4 mm) or in sites with attachment loss 〈2 mm (P〈0.05). P. gingivalis strains withprtC+/fimA+ also showed higher frequency in gingival index (GI)=3 than in GI=1 group (P〈0.05). Conclusion: Infection ofP. gingivalis with prtC+/fimA+ and A. actinomycetemcomitans with lktA+ correlates with periodontal destruction of CP in Chinese. Nonetheless P. gingivalis fim4, prtC genes and A. actinomycetem- comitans lktA gene are closely associated with periodontal destruction, while A. actinomycetemcomitansfap gene is not.  相似文献   
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