USB标准下图像数据长度转换的实现

数字图像传感器的量化长度往往与USB接口的要求不匹配。为了节省带宽并提高传输效率,需要对数据进行长度转换。采用可编程器件对数据进行转换,可以适应各种不同的数据长度并且有较好的灵活性和高速性。为此提出了一种基于目前主流芯片的高效解决方案。     

Insights on evolution of virulence and resistance from the whole-genome analysis of a predominant methicillin-resistantStaphylococcus aureus clone sequence type 239 in China

Earlier, we reported that ST239 was the 15-year predominant methicillin-resistant Staphylococcus aureus （MRSA） clone in China. In this study, MRSA strain CN79 belonging to ST239 and isolated from blood was used to determine the whole tive genomics analysis was genome sequence. Compara- done between MRSA CN79 and 25 sequenced S. aureus in the NCBI GenBank data- base. A total of 2,734 protein-encoding genes were iden- tified in the MRSA CN79 genome, which carries 11 antibiotic resistance genes and 65 virulence genes. Two prophages phiCN79A and phiNM3-1ike were found on the MRSA CN79 genome. MRSA CN79 carries 30 specific genes that are absent from the 25 sequenced S. aureus genomes. Most of them were prophage-related genes. Several antibiotic resistance genes, such as [3-1actamase and ABC-type multidrug transport system gene, were located on the genomic island vSal3. The antibiotic resis- tance genes, such as tet （M）, ermA1, and blaZ, were also located on different transposons. The virulence genes sea,map, hlb, and sak are located on phiNM3-1ike prophage and the exotoxin genes are carried on the genomic island vSaa. These results suggest that ST239 MRSA strains are widespread owing to horizontal acquisition of the mobile genetic elements harbored antibiotic resistance genes and virulence genes in response to environmental selective pressures, such as antibiotics and the human immune sys- tem during evolution.     

浅谈地域文化在景观设计中的意义

地域文化是景观设计的创作源泉,在全球化的背景下,文章探讨了怎样处理好景观设计中地域文化的继承与创新问题.     

甲烷催化燃烧催化剂的研究进展

甲烷催化燃烧的目的是通过催化作用降低其起燃温度(T_(10))和完全转化温度(T_(90)),加深其氧化程度,从而提高燃料的利用率。简述了甲烷催化燃烧反应的机理,从种类、制备方法以及催化性能等方面详细介绍了甲烷催化燃烧催化剂的最新进展。贵金属催化剂的催化性能优越,但高成本以及热稳定性差等因素极大地限制了其应用;非贵金属催化剂尤其是复合金属氧化物催化剂(例如钙钛矿型复合金属氧化物催化剂和六铝酸盐系列催化剂等)拥有较高的催化活性,因其成本低,有更好的发展前景。提高非贵金属催化剂的低温催化活性和高温热稳定性是今后甲烷催化燃烧催化剂的主要研究方向。     

Trust-based context-aware mobile social network service recommendation

The service recommendation mechanism as a key enabling technology that provides users with more proactive and personalized service is one of the important research topics in mobile social network (MSN). Meanwhile, MSN is susceptible to various types of anonymous information or hacker actions. Trust can reduce the risk of interaction with unknown entities and prevent malicious attacks. In our paper, we present a trust-based service recommendation algorithm in MSN that considers users’ similarity and friends’ familiarity when computing trustworthy neighbors of target users. Firstly, we use the context information and the number of co-rated items to define users’ similarity. Then, motivated by the theory of six degrees of space, the friend familiarity is derived by graph-based method. Thus the proposed methods are further enhanced by considering users’ context in the recommendation phase. Finally, a set of simulations are conducted to evaluate the accuracy of the algorithm. The results show that the friend familiarity and user similarity can effectively improve the recommendation performance, and the friend familiarity contributes more than the user similarity.     

齐墩果酸C-28位修饰物的合成与表征及其抑菌活性研究

齐墩果酸属于五环三萜类化合物,在自然界广泛分布,并且显示出多种生物活性,如：抗菌、抗炎、抗病毒及抗肿瘤等。但对其衍生物抑菌活性研究方面的报道较少。为了更为深入地研究齐墩果酸及其衍生物的构效关系,我们以具有较好生物活性的齐墩果酸为先导化合物,通过对其C-28位进行结构修饰,设计合成了6种未见报道的齐墩果酸衍生物。目标化合物的结构经IR和1HNMR表征确证,并对金黄色葡萄球菌、抗甲氧西林金黄色葡萄球菌、抗喹诺酮金黄色葡萄球菌、变形链球菌和大肠杆菌进行抑菌活性测试。结果表明,经修饰后的齐墩果酸衍生物对变形链球菌的抗菌活性较母体化合物有不同程度的提升。     

一个不适定问题的频域对称截断正则化方法

如下问题　　　　　　ut+ux=uxxu(1,t) =g(t)u(x,0 ) =0　　0≤ x<∞　 0 相似文献   

潜江凹陷蚌湖地区潜江组超压成因机理

蚌湖向斜带位于潜江凹陷中部,其潜江组普遍发育超压系统.综合超压成因机理的各种分析方法,基于测井曲线特征和烃源岩成熟度特征,从压实不均衡和生烃作用两方面对蚌湖地区的超压成因机理进行了系统分析.研究结果表明,1在超压段泥岩声波时差曲线偏离正常压实线,其拐点深度为2150~3180 m,蚌湖地区储层实测超压顶界面深度约为2200 m,在埋深较浅地区,超压成因以不均衡压实作用为主,在埋深较大地区,超压成因为不均衡压实和生烃共同作用;2超压顶界面埋深与生烃门限表现出较好的一致性,在2200 m深度其镜质体反射率Ro值为0.55%,说明生烃作用对蚌湖地区超压的发育亦具有一定的贡献,由此认为,压实不均衡和生烃增压作用是蚌湖地区超压发育的主要机理.     

5,5′-二硫硝基苯甲酸分光光度法测定微生物酶法转化液中的L-半胱氨酸

以5,5′-二硫硝基苯甲酸(DTNB)分光光度法测定微生物法转化液中的L-半胱氨酸,测定波长为412 nm,L-半胱氨酸在5～40μg/mL浓度范围内呈良好的线性关系(R2>0.999 3),高、中、低浓度水平的L-半胱氨酸加标回收率为99.2%～102.5%,RSD为2.3%.该法准确、简单、快速,可以用于对微生物转化进行实时检测.     

三角形受压缘钢梁腹板的屈曲荷载

本文将三角形受压缘钢梁腹板假设成上边固定另三边简支的弹性矩形薄板,按浅梁理论计算腹板的中面力,用配点法求解腹板的屈曲荷载。对结果进行分析后得知,在弹性范围内屈曲荷载的理论值与试验值的误差一般不超过6%。本文还在理论和试验研究的基础上,提出了三种较好的实用计算方法:电算法、查表法和近似公式计算法。电算法具有输入数据少、电算时间短、结果精度高等优点,查表法和近似公式计算法比电算法更实用且能求得较好的结果。