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排序方式: 共有87条查询结果,搜索用时 312 毫秒
1.
利用SD对壳模型讨论了偶偶Pt核低激发态的集体性质. 结果发现在该模型下, 利用一个仅含有3个参数的哈密顿量, 可以很好地再现偶偶Pt核低激发谱的集体性质.  相似文献   
2.
运动对去卵巢大鼠骨元素代谢的影响   总被引:10,自引:7,他引:10  
用测定骨元素含量的方法,分析了运动对正常大鼠和切除双侧卵巢后的大鼠骨元素代谢的影响。将健康4个月龄雌性SD大鼠44只随机分成5组:(1)非去势非运动组;(2)非去势+运动组;(3)假去势非运动组;(4)去势非运动组;(5)去势+运动组。运动组用大鼠专用跑台中等运动强度训练,持续10周。结果表明,去卵巢大鼠骨Ca,Mg,S,Mn,Zn等含量显著降低,P含量显著增加。运动训练可使去卵巢大鼠降低的骨Ca,Mg,S,Mn,Zn等含量显著回升,骨P含量显著回降。提示中等强度运动训练可对抗由于去卵巢所引起的骨元素代谢紊乱。  相似文献   
3.
《中国化学会会志》2017,64(1):80-86
A convenient, practical, green, and environmentally friendly method was developed for the synthesis of benzothiazoles from 2‐aminothiophenol and various aldehydes. Bis‐benzothiazoles were synthesized in high yield under mild reaction conditions. Products were obtained in the presence of in situ prepared Fe(SD )3 [iron(III ) dodecyl sulfate] as a combined Lewis acid–surfactant catalyst (LASC ) in water under ultrasound irradiation.  相似文献   
4.
Resveratrol is a polyphenol that has numerous interesting biological properties, but, per os, it is quickly metabolized. Some of its metabolites are more concentrated than resveratrol, may have greater biological activities, and may act as a kind of store for resveratrol. Thus, to understand the biological impact of resveratrol on a physiological system, it is crucial to simultaneously analyze resveratrol and its metabolites in plasma. This study presents an analytical method based on UHPLC-Q-TOF mass spectrometry for the quantification of resveratrol and of its most common hydrophilic metabolites. The use of 13C- and D-labeled standards specific to each molecule led to a linear calibration curve on a larger concentration range than described previously. The use of high resolution mass spectrometry in the full scan mode enabled simultaneous identification and quantification of some hydrophilic metabolites not previously described in mice. In addition, UHPLC separation, allowing run times lower than 10 min, can be used in studies that requiring analysis of many samples.  相似文献   
5.
The development and characterization of a magnetic bead (MB)-quantum dot (QD) nanoparticles based assay capable of quantifying pathogenic bacteria is presented here. The MB-QD assay operates by having a capturing probe DNA selectively linked to the signaling probe DNA via the target genomic DNA (gDNA) during DNA hybridization. The signaling probe DNA is labeled with fluorescent QD565 which serves as a reporter. The capturing probe DNA is conjugated simultaneously to a MB and another QD655, which serve as a carrier and an internal standard, respectively. Successfully captured target gDNA is separated using a magnetic field and is quantified via a spectrofluorometer. The use of QDs (i.e., QD565/QD655) as both a fluorescence label and an internal standard increased the sensitivity of the assay. The passivation effect and the molar ratio between QD and DNA were optimized. The MB-QD assay demonstrated a detection limit of 890 zeptomolar (i.e., 10−21 mol L−1) concentration for the linear single stranded DNA (ssDNA). It also demonstrated a detection limit of 87 gene copies for double stranded DNA (dsDNA) eaeA gene extracted from pure Escherichia coli (E. coli) O157:H7 culture. Its corresponding dynamic range, sensitivity, and selectivity were also presented. Finally, the bacterial gDNA of E. coli O157:H7 was used to highlight the MB-QD assay's ability to detect below the minimum infective dose (i.e., 100 organisms) of E. coli O157:H7 in water environment.  相似文献   
6.
本文采用MVM 屈服准则,用相关联流动法则建立材料的本构关系.对于实际工程中常见的轴对称问题(平面应力、平面应变),进行弹塑性分析,给出求解问题的一组微分方程.采用Prager 假设,给出应力场和位移场.在分析中可以看出:对于平面应变问题,当v≠0.5时,求解应力场的问题是非静定的;当v=0.5或在平面应力问题中,求解应力的问题是静定的,方程组易于求解.通过数值计算考察SD 效应对结构的影响.结果表明,在压缩过程中,SD 效应增强了结构抵抗塑性变形的能力.  相似文献   
7.
运用高效液相色谱-电喷雾离子阱串联质谱(HPLC-ESI-MS/MS)技术,建立了快速、简单、灵敏的SD大鼠肺中N7-(2-羟乙基硫代乙基)鸟嘌呤(N7-HETEG)的检测方法。以N7-苯甲基鸟嘌呤为内标,用甲醇和水为流动相进行梯度洗脱,正离子模式检测,方法的检出限(信噪比(S/N)≥10)为300 pg/mL,定量限(S/N≥20)为850 pg/mL。在300 pg/mL~1.28 μg/mL的质量浓度范围内,N7-HETEG浓度与N7-HETEG和内标的峰面积比呈良好的线性关系(线性相关系数为0.9929)。高、中、低3个添加水平的日内测定精密度(以相对标准偏差(RSD)计)和日间测定精密度均小于10%(n=7),回收率为100%~132%。对SD大鼠背部皮肤染芥子气,剂量分别为5.5、11、22和45 mg/kg,染毒4 d后检测大鼠肺脏中N7-HETEG的含量。各个不同染毒剂量下,每克组织中分别检测到(0.56±0.16)、(0.67±0.12)、(1.36±0.68)和(5.14±0.92) ng N7-HETEG, N7-HETEG的含量随着染毒剂量的增大而增大,表明N7-HETEG可用作芥子气暴露的体内生物标志物。  相似文献   
8.
本文首先给出了一个右连续上鞅的SD提升,在引进S-上鞅和强S-上鞅概念之后,研究了一一致可积上鞅与S-上鞅,类上鞅与强S-上鞅之间的关系,并得到了S-上鞅与强S-上鞅的许多性质,作为其直接结果,给出了类上鞅的Doob-MNeyer分解。  相似文献   
9.
Efficient parallel algorithms are presented, on the CREW PRAM model, for generating a succinct encoding of all pairs shortest path information in a directed planar graphG with real-valued edge costs but no negative cycles. We assume that a planar embedding ofG is given, together with a set ofq faces that cover all the vertices. Then our algorithm runs inO(log2 n) time and employsO(nq+M(q)) processors (whereM(t) is the number of processors required to multiply twot×t matrices inO(logt) time). Let us note here that wheneverq<n then our processor bound is better than the best previous one (M(n)).O(log2 n) time,n-processor algorithms are presented for various subproblems, including that of generating all pairs shortest path information in a directedouterplanar graph. Our work is based on the fundamental hammock-decomposition technique of G. Frederickson. We achieve this decomposition inO(logn log*n) parallel time by usingO(n) processors. The hammock-decomposition seems to be a fundamental operation that may help in improving efficiency of many parallel (and sequential) graph algorithms.This work was partially supported by the EEC ESPRIT Basic Research Action No. 3075 (ALCOM) and by the Ministry of Industry, Energy and Technology of Greece.  相似文献   
10.
李林  袁也  刘红 《运筹与管理》2018,27(6):14-20
文章首先基于演化博弈理论,研究了无政府干预下协同创新主体采取合作策略的演化博弈规律;其次基于系统动力学理论,分析了政府干预下协同创新主体采取合作策略的演化博弈规律,并构建了系统动力学模型及运用Vensim软件作出了仿真分析。仿真发现,协同创新主体间的合作主要受政府惩罚力度、采取的惩罚机制以及创新主体采取投机行为所产生的生产成本的影响。因此,政府提高惩罚力度并采用动态惩罚机制,能促使协同创新主体更快地采取合作策略进行协同创新。  相似文献   
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