Parameters affecting the frequencies of transformation and co-transformation with synthetic oligonucleotides in yeast.

Factors influencing the direct transformation of the yeast Saccharomyces cerevisiae with synthetic oligonucleotides were investigated by selecting for cyc1 transformants that contained at least partially functional iso-1-cytochrome c. Approximately 3 x 10(4) transformants, constituting 0.1% of the cells, were obtained by using 1 mg of oligonucleotide in the reaction mixture. Carrier, such as heterogeneous oligonucleotides, enhanced transformation frequencies. Transformation frequencies were dramatically reduced if the oligonucleotides had a large number of mismatches or had terminally located mismatches. Transformation with oligonucleotides, but not with linearized double-strand plasmid, was efficient in a rad52- strain, suggesting that the pathway for transformation with oligonucleotides is different from that with linearized double-strand plasmid. We describe a procedure of co-transformation with two oligonucleotides, one correcting the cyc1 defect of the target allele in the host strain, and the other producing a desired amino acid alteration elsewhere in the iso-1-cytochrome c molecule; approximately 20% of the transformants obtained by co-transformation contained these desired second alterations.     

面向机器人装配设计与规划的集成框架

本文针对面向机器人装配的产品设计与装配规划中的关键问题,分析实际产品设计与装配规划的一般过程,提出了将面向机器人装配的产品设计与装配规划进行系统集成的框架,并对系统的各个模块的功能和实现作了研究探讨,通过在工程实践中的应用验证了其正确性和有效性．     

土壤取样测氡的可行性研究与实现

论述了土壤中氡的析出机理,通过设计实验验证了土壤取样测氡的可行性。运用活性炭吸附法、主动抽吸法和径迹蚀刻法分别测定了野外实地与土壤样品中的氡及其子体含量,并测定了土壤样品的镭含量。实验结果表明:运用土壤取样测氡的方法是可行的,其数据稳定性好于野外实测数据的稳定性;其次,野外测量会受到温度、湿度、降雨量、压强等气象条件的较大影响;此外,取样时要尽量避开雨后取样和在有断裂带、褶皱带等复杂地质构造的区域内取样。     

密闭腔体法准确测量建材氡析出率比较研究

密闭腔体法(closed chamber method)是目前建材氡析出率测量中使用较为广泛的一种方法。使用密闭腔体法测量建材氡析出率,在建材的前处理上,大体上将长方体建材分为完全裸露、包裹留下一面和留下两面三种方法进行测量。本文从建材氡析出率测量的基本理论模型出发,细致比较分析了不同包裹方法测量得到的氡析出率的真实涵义,并结合理论分析和实验验证,提出了合理的修正方法,认为包裹留一面和留两面适合作为建材氡析出率的测量方法。     

基于GIS的土地信息系统的设计与实现

土地信息系统是面向土地管理的地理信息系统,是由土地相关信息组成的数据库以及收集、描述、处理和分配这些数据的技术方法组成.文中介绍了一个土地信息系统的组成,并着重讨论了系统的技术要点及实现方法.     

Using a Fragment‐Based Approach To Target Protein–Protein Interactions

The ability to identify inhibitors of protein–protein interactions represents a major challenge in modern drug discovery and in the development of tools for chemical biology. In recent years, fragment‐based approaches have emerged as a new methodology in drug discovery; however, few examples of small molecules that are active against chemotherapeutic targets have been published. Herein, we describe the fragment‐based approach of targeting the interaction between the tumour suppressor BRCA2 and the recombination enzyme RAD51; it makes use of a screening pipeline of biophysical techniques that we expect to be more generally applicable to similar targets. Disruption of this interaction in vivo is hypothesised to give rise to cellular hypersensitivity to radiation and genotoxic drugs. We have used protein engineering to create a monomeric form of RAD51 by humanising a thermostable archaeal orthologue, RadA, and used this protein for fragment screening. The initial fragment hits were thoroughly validated biophysically by isothermal titration calorimetry (ITC) and NMR techniques and observed by X‐ray crystallography to bind in a shallow surface pocket that is occupied in the native complex by the side chain of a phenylalanine from the conserved FxxA interaction motif found in BRCA2. This represents the first report of fragments or any small molecule binding at this protein–protein interaction site.     

RAD7测量氡析出率的方法探讨

RAD7是一种性能优良的氡检测仪,常用来测量空气氡浓度。本文介绍了RAD7测氡仪的测量原理,并研究了应用RAD7测氡仪测量土壤、废石等表面介质氡析出率的方法,对集氡罩进行了改进,与常用的HDC-C测氡仪在氡析出率测量效果上进行了比较,结果令人满意。