用小测度集上的小Riemann和刻划Lebesgue积分和Henstock积分

在小测度集上用小Ｒｉｅｍａｎｎ和刻划了Ｌｅｂｓｇｕｅ积分和Ｈｅｎｓｔｏｃｋ积分的实质．     

一种遗传算法在集合覆盖问题中的应用研究

利用遗传算法的思想把集合覆盖问题进行适当的转化并提出了一种适用于求解该问题的改进遗传算法,通过对种群中的染色体进行启发式改进和遗传参数的选取,来达到求解的目的.     

Recruitment of cytosolic proteins to a secretory granule membrane depends on Ca2+-calmodulin

An increase in free calcium triggers catecholamine secretion from chromaffin cells and calmodulin is strongly implicated as the intracellular Ca2+ receptor. In our recent studies of calmodulin action in the chromaffin cell, micromolar Ca2+ concentrations resulted in calmodulin and cytosolic proteins becoming bound to the chromaffin granule membranes. We now report that calmodulin is bound with high affinity to granule membrane proteins of molecular weights (Mrs) 25,000 and 22,000 (25K and 22K) at low Ca2+ (less than 10(-8) M) and to proteins with Mrs 69K and 50K at high Ca2+ (greater than 1 microM). Other cytosolic components (Mrs 70K, 36K, 34K and 32K) require calmodulin for their interfraction with membrane. These proteins separately bound to calmodulin-Sepharose at high Ca2+ concentrations. Although the functions of these adrenal proteins have not been established, the 34K and 32K Mr components co-migrate with clathrin light chains isolated from medullary coated vesicles and the Mr 34K components from both sources share the same one-dimensional peptide map. These interactions were observed at micromolar Ca2+ levels at 'intracellular' conditions of pH and ionic strength and would be expected to occur during secretion from the chromaffin cell.     

基于佳点集遗传算法的边缘检测

为了提高遗传算法应用于边缘检测的收敛速度,提出了一种基于佳点集遗传算法(GGA)的边缘检测方法.该方法利用佳点集理论构造交叉操作使得子代保留最能代表其家族性能的双亲共同基因以提高算法收敛速度.在用遗传算法进行边缘检测之前,将图像的灰度值特征空间转换为模糊熵特征空间,然后运用模糊熵理论对图像进行相异性增强处理,滤去非边缘像素以便缩小解空间规模,为提高算法的收敛速度提供了另一个有效的途径.实验结果表明,所提出的图像边缘检测方法具有较好收敛效率,所检测出的图像边缘细节丰富、单边缘、定位准确.     

桑树遗传转化技术中抗生素的浓度优化研究

调查了抗生素对根癌农杆菌介导的桑品种“新一之濑”遗传转化不同培养阶段外植体生长、分化或生根的影响及其对农杆菌的抑制效果 ,并确定 :在叶盘 (或茎尖 )转化筛选培养阶段 ,Kan (卡那霉素 )和 Cab (羧苄青霉素 )适宜浓度分别为 3 0～ 40 mg/ L和 2 0 0～40 0 mg/ L (或 6 0～ 80 mg/ L和 2 0 0～ 6 0 0 mg/ L ) ,在抗性芽继代 (或生根 )培养阶段 ,Kan和Cab分别为 40～ 5 0 mg/ L和 1 0 0～ 2 0 0 mg/ L (或 5～ 1 0 mg/ L和 5 0～ 1 0 0 mg/ L) .Cef(头孢霉素 )对桑树各种外植体的影响效果与 Cab相似 ,但两者的抑菌效果因农杆菌菌株、外植体类型以及培养阶段的不同而存在差异 ,用含 Kan、Rif(利福平 )和 Str(链霉素 )的 LB培养基浸渍叶盘则出现分化率下降、褐化死亡较严重的现象 .     

用遗传算法进行RFD装置优化设计

免维修流体输送装置RFD由压缩空气做动力,通过气液换能驱动被输送液体间歇性出料。该装置不含运动部件,其优化设计是关系到装置高效稳定运行的关键理论。文中分析了传统枚举法和边际效用法在方案搜索中存在的问题,重点讨论了遗传算法在多目标高维优化问题中的应用,通过计算实例比较了3种方法的计算结果,得出遗传算法在本问题求解中的优势。最后,针对流量和扬程需求,采用遗传算法进行了装置的系列化设计,并分析了有关结构参数和运行参数的变化规律,进一步给出了不同密度和粘度下,RFD装置输送流量的换算关系,为RFD装置的工业设计打下坚实的基础。     

Template-directed synthesis of a genetic polymer in a model protocell

Contemporary phospholipid-based cell membranes are formidable barriers to the uptake of polar and charged molecules ranging from metal ions to complex nutrients. Modern cells therefore require sophisticated protein channels and pumps to mediate the exchange of molecules with their environment. The strong barrier function of membranes has made it difficult to understand the origin of cellular life and has been thought to preclude a heterotrophic lifestyle for primitive cells. Although nucleotides can cross dimyristoyl phosphatidylcholine membranes through defects formed at the gel-to-liquid transition temperature, phospholipid membranes lack the dynamic properties required for membrane growth. Fatty acids and their corresponding alcohols and glycerol monoesters are attractive candidates for the components of protocell membranes because they are simple amphiphiles that form bilayer membrane vesicles that retain encapsulated oligonucleotides and are capable of growth and division. Here we show that such membranes allow the passage of charged molecules such as nucleotides, so that activated nucleotides added to the outside of a model protocell spontaneously cross the membrane and take part in efficient template copying in the protocell interior. The permeability properties of prebiotically plausible membranes suggest that primitive protocells could have acquired complex nutrients from their environment in the absence of any macromolecular transport machinery; that is, they could have been obligate heterotrophs.     

Establishment of a genetic transformation system for maize inbred P9-10

It was found that the supplement of 10 -4 mol/L AgNO3 in N6 medium enhanced the induction of type Ⅰ embryogenic calli from immature embryos of maize inbred P9-10. After high-osmotic treatment, the induced calli was taken as transformation recipient to be bombarded with plasmid pMG6 carrying synthetic Bt gene by PDS-1000/He genegun. A total of 14 resistant calli were obtained after screening subsequently on the mediums with gradually increasing selective pressure. 10 plants were regenerated from the resistant calli on 3 different induction media, and 8 out of the 10 regenerated plants were confirmed to be integrated with Bt gene by PCR and Southern blotting analysis. Results of ELISA showed that the Bt-protein content in the leaves of the transgenic plants varied between 20-200 ng/g fresh weight.     

小波变换集遗传算法神经网络的径流预测建模

为获得更精确的径流预报结果,利用dmey小波变换对径流时间序列分解为高频信号和低频信号,再使用遗传算法优化的BP神经网络分别对其进行预测,最后利用dmey小波逆变进行重构,以此建立径流总量预测模型。通过对柳江径流总量进行实例分析,并与遗传算法优化的神经网络模型、BP神经网络模型及传统的时间序列分析方法对比,该方法获得更准确的预测结果。研究结果表明该模型能充分反映径流时间序列趋势,预报稳定性好,预报准确率高,为径流时间序列预测提供一个有效建模方法。     

基于μ综合的热轧动态设定型AGC鲁棒控制

通过对热轧动态设定型AGC控制系统模型进行理论分析,针对工程实际提出了一种基于μ综合的鲁棒控制方法.当系统中存在轧机刚度摄动时,热轧动态设定型AGC控制仍能实现期望的控制性能.通过引入表征系统性能的虚拟块,应用主环定理将动态设定型AGC系统在模型摄动下设计满足性能要求的控制器问题转换为广义系统的鲁棒稳定性问题,实现了系统鲁棒性能.它克服了使用H∞方法解决该问题的鲁棒性能缺点,其设计目标真实反映控制目标,方法更加有效.依据现场数据的仿真实验表明,基于μ综合的鲁棒控制方法比H∞方法具有更好的鲁棒性能.     

A hybrid genetic algorithm for reduct of attributes in decision system based on rough set theory

Knowledge reduction is an important issue when dealing with huge amounts of data. And it has been proved that computing the minimal reduct of decision system is NP-complete. By introducing heuristic information into genetic algorithm, we proposed a heuristic genetic algorithm. In the genetic algorithm, we constructed a new operator to maintaining the classification ability. The experiment shows that our algorithm is efficient and effective for minimal reduct, even for the special example that the simple heuristic algorithm can't get the right result.     

一种改进的Rough集属性约简启发式遗传算法

属性约简是知识发现中的关键问题之一 .为了能够有效地获取决策表中属性最小相对约简 ,提出了一种在优化初始群体基础上提高算法性能的启发式遗传算法 .首先 ,通过构造一个新的算子 ,将信息论角度定义的属性重要性度量作为启发式信息 ,来描述所选择的属性子集对论域中确定分类子集的影响 ;接着 ,以此为基础并结合遗传算法 ,选择一些经过优化的染色体作为初始群体 ,在加强局部搜索能力的同时保持了该算法全局寻优的特性 .最后 ,从理论上对算法做了分析 ,证明了新算子所选择的属性子集对原有属性分类能力保持不变 .试验分析表明 ,该算法能有效地对决策表属性进行约简     

纳米材料介导植物遗传转化的研究进展

植物遗传转化对于改善农作物的性状,培育高产、优质、多抗性的新品种,从而降低农药和肥料的使用量等至关重要.传统的遗传转化方法存在着诸多局限性,如物种的不普适性,植物组织易被破坏,成本高、耗时长和转化效率低等.近几年,纳米材料介导的植物遗传转化策略逐渐被研究和尝试,并显示出了不受物种限制、生物相容性良好和操作简单等一系列优势.文章对常用的传统遗传转化方法进行了总结,重点介绍了近年来多种纳米材料在植物遗传转化中的研究和应用进展,并讨论和展望了纳米材料在植物遗传转化应用领域的挑战和发展前景.     

农杆菌介导转化水稻方法的改进

采用培矮64S和9311两种籼稻为材料,研究了影响农杆菌介导转化的几种因素．研究结果表明,预培养4d的幼胚最适宜作为农杆菌介导转化的受体,其次是来源于幼胚和成熟胚的生长状态良好的胚性愈伤组织．以AAM培养基作为共培养培养基,对于农杆菌EHA105（pUblm）来说,菌液浓度为OD600值=0．8时,愈伤组织的转化率最高．在农杆菌侵染愈伤组织过程中,通过负压处理可明显提高愈伤组织的转化频率．在愈伤组织浸染后,以含一定浓度的Ca^2＋和表面活性剂Tween20的溶液处理可明显提高水稻愈伤组织的转化频率．     

雄性二倍体毛白杨再生体系的构建和遗传转化的研究

【目的】建立雄性二倍体毛白杨再生体系,构建稳定的遗传转化方法,为进一步研究毛白杨基因功能提供试验平台。【方法】以雄性二倍体毛白杨的幼嫩茎段和叶片为外植体,1/2 MS为基本培养基,通过调整6-BA、IAA和TDZ激素浓度进行再生体系筛选;采用农杆菌EHA105介导叶盘法,控制预培养时间、菌液浓度、侵染时间、共培养时间和卡那霉素筛选浓度,进行遗传转化;以幼嫩叶片原生质体为受体细胞,PEG介导转化荧光标记基因EGFP,进行瞬时表达。【结果】雄性二倍体毛白杨再生过程包括继代、芽伸长和生根3个阶段,其培养基组分分别为1/2 MS+0.5 mg/L 6-BA+0.5 mg/L NAA+0.005 mg/L TDZ、1/2 MS+0.5 mg/L 6-BA+0.3 mg/L NAA和1/2 MS+0.3 mg/L NAA+0.5 mg/L IBA,该条件下生根率为96.7%,增殖系数为4.47。遗传转化过程包括预培养、农杆菌侵染、共培养、抗性筛选和生根5个阶段,其中预培养为12 h、农杆菌浓度OD₆₀₀为0.4、侵染时间为20 min、共培养时间为24 h、卡那霉素(30 mg/L)筛选45 d和抗性苗生根20 d。试验共获得86株抗性植株,其中14株分子鉴定结果为阳性。在40% PEG4000的介导下,EGFP基因瞬间转化效率为50%。【结论】雄性二倍体毛白杨再生周期短、遗传转化稳定,是杨树基础研究的理想材料。本研究拓宽了杨树遗传转化体系,为杨树分子辅助育种提供了新途径。     

Reconstitution of active dimeric ribulose bisphosphate carboxylase from an unfoleded state depends on two chaperonin proteins and Mg-ATP.

In vitro reconstitution of active ribulose bisphosphate carboxylase (Rubisco) from unfolded polypeptides is facilitated by the molecular chaperones: chaperonin-60 from Escherichia coli (groEL), yeast mitochondria (hsp60) or chloroplasts (Rubisco sub-unit-binding protein), together with chaperonin-10 from E. coli (groES), and Mg-ATP. Because chaperonins are ubiquitous, a conserved Mg-ATP-dependent mechanism exists that uses the chaperonins to facilitate the folding of some other proteins.     

转基因玉米遗传转化的研究进展

转基因玉米是目前植物基因工程的研究热点之一,已有转基因抗虫玉米、抗除草剂玉米进入商品化生产。通过对转基因玉米遗传转化方法的研究,概括了目前在转基因玉米的遗传转化中所用的各种方法、及其优缺点,以及已取得的成果和遗传转化的检测分析方法的研究进展。     

Involvement of targeted proteolysis in plant genetic transformation by Agrobacterium

Genetic transformation of plant cells by Agrobacterium represents a unique case of trans-kingdom DNA transfer. During this process, Agrobacterium exports its transferred (T) DNA and several virulence (Vir) proteins into the host cell, within which T-DNA nuclear import is mediated by VirD2 (ref. 3) and VirE2 (ref. 4) and their host cell interactors AtKAP-alpha and VIP1 (ref. 6), whereas its integration is mediated mainly by host cell proteins. The factors involved in the uncoating of T-DNA from its cognate proteins, which occurs before integration into the host genome, are still unknown. Here, we report that VirF-one of the few known exported Vir proteins whose function in the host cell remains unknown-is involved in targeted proteolysis of VIP1 and VirE2. We show that VirF localizes to the plant cell nucleus and interacts with VIP1, a nuclear protein. VirF, which contains an F-box motif, significantly destabilizes both VIP1 and VirE2 in yeast cells. Destabilization of VIP1 in the presence of VirF was then confirmed in planta. These results suggest that VIP1 and its cognate VirE2 are specifically targeted by the VirF-containing Skp1-Cdc53-cullin-F-box complex for proteolysis. The critical role of proteasomal degradation in Agrobacterium-mediated genetic transformation was also evident from inhibition of T-DNA expression by a proteasomal inhibitor.     

基于真值表变换的可逆逻辑综合算法

为实现将给定的二元可逆函数快速综合为相应电路,并保持其结果的最优或较优,提出一种基于真值表变换的快速综合算法.可逆函数与置换同构,任意置换均可表示为若干对换的乘积,通过将可逆函数转化为一系列对换的乘积,从对换的乘积中综合电路.对于3bit逻辑电路只有28种对换,事先将28种对换的最优电路存入库中生成3bit电路综合基,通过在库中查找快速生成可逆电路.根据逻辑门可交换规则引入优化方法,完成快速综合算法.结果表明,该方法不但可以提高可逆逻辑综合的效率,而且结构简单,易于实现,可以O(4n)的时间效率快速综合任意3bit可逆逻辑电路,实现综合结果达到或接近最优.