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421.
Cleavage of DNA pUC19 by [Cu(saldien)(NH3)]C12 (here, saldien=bis(salicylicdene)-diethylenetriamine) was investigated at different pHs, times, concentrations, and 37℃. It wasfound that the copper( Ⅱ ) complex could cleave DNA without added coreactants.  相似文献   
422.
文章从实际出发,在加强技术创新,开发新产品和转变机制及股份制改造等方面进行了论述。  相似文献   
423.
In previous paper and work, we reported the synthesis and cytotoxicity studies of a novel series of short chain peptide conjugates of the cytotoxic agent 2, 6-dimethoxyhydro -quinone-3-mercaptoacetic acid1 (DMQ-MA). The DMQ-MA is a derivative of 2,6-dimethoxybenzoquinone, which is a natural product of fermented wheat germ and found to have a wide spectrum of cytotoxicity against various tumor cell lines under the synergistic activation of L-ascorbic acid (AH2)2,3. Compared with DMQ, DMQ…  相似文献   
424.
An efficient strategy for CrCl3-mediated production of 5-hydroxymethylfurfural (HMF) in ca. 60% and 90% isolated yields from cellulose and glucose, respectively, in ionic liquid under microwave irradiation is presented.  相似文献   
425.
A new active fault tolerant control scheme based on active fault diagnosis is proposed to address the component/actuator faults for systems with state and input constraints. Firstly, the active fault diagnosis is composed of diagnostic observers, constant auxiliary signals, and separation hyperplanes, all of which are designed offline. In online applications, only a single diagnostic observer is activated to achieve fault detection and isolation. Compared with the traditional multi-observer parallel diagnosis methods, such a design is beneficial to improve the diagnostic efficiency. Secondly, the active fault tolerant control is composed of outer fault tolerant control, inner fault tolerant control and a linear-programming-based interpolation control algorithm. The inner fault tolerant control is determined offline and satisfies the prescribed optimal control performance requirement. The outer fault tolerant control is used to enlarge the feasible region, and it needs to be determined online together with the interpolation optimization. In online applications, the updated state estimates trigger the adjustment of the interpolation algorithm, which in turn enables control reconfiguration by implicitly optimizing the dynamic convex combination of outer fault tolerant control and inner fault tolerant control. This control scheme contributes to further reducing the computational effort of traditional constrained predictive fault tolerant control methods. In addition, each pair of inner fault tolerant control and diagnostic observer is designed integratedly to suppress the robust interaction influences between estimation error and control error. The soft constraint method is further integrated to handle some cases that lead to constraint violations. The effectiveness of these designs is finally validated by a case study of a wastewater treatment plant model.  相似文献   
426.
类风湿因子(RF)免疫吸附剂的制备及性能研究   总被引:1,自引:0,他引:1  
以球形纤维素为载体,经环氧氯丙烷活化后键联活性配基热聚人IgG,制备类风湿因子(RF)免疫吸附剂,可望用于血液灌流治疗类风湿关节炎。研究了配基的固定化条件及吸附剂的吸附性能。实验结果表明,吸附剂对IgGRF、IgMRF、IgARF的吸附率分别达到69.6%、70.3%、77.0%。  相似文献   
427.
Due to the importance of oxidative degradation of nucleic acids in mutagenesis, carcinogenesis, and aging, a large number of chemical and biological investigations have been recently published1. Artificial metallonucleases have been proven to be efficient tools for the footprinting and sequence-specific targeting of nucleic acids1,2. They usually require high concentrations of the complex and of an external reducing agent (such as dithiothreitol, DTT) to form a reactive species in situ, the f…  相似文献   
428.
疏水性多糖的合成及荧光法研究其在水中的自聚集行为   总被引:2,自引:0,他引:2  
由胆固醇与1,6-已二异氰酸酯反应合成了1,6-已二异氰酸酯胆固醇单脂(I),然后通过葡聚糖与(I)反应合成了具有自聚集性质的葡聚糖,测得葡聚糖主链上每100个糖环含有3-5个胆固醇。我们采用探针式超声波来制得胆固醇修饰葡聚糖「CHD」的水溶液,同时用N-苯基-α-萘胺「PNA」作为荧光探针来研究CHD自聚集过程。在实验中我们发现,每一种葡聚糖溶液,都存在着一个临界浓度。在此浓度之上,PNA的荧光  相似文献   
429.
Molecular modeling methods have been applied to the structural characterization of the interaction between chiral metal complexes [Co(phen)2dppz]3 (where phen = 1, 10-phenanthroline, dppz = dipyrido[3,2-a: 2', 3'-c]phenazine) and the oligonucleotide (B-DNA fragment). The natures of two kinds of the binding modes, which are currently intense controversy, have been explored. Barton proposed that there is enantio-selective DMA binding by the octahedral complexes and intercalative access by these complexes from the major groove; but Norden suggested that both enantiomers bind extremely strongly to DNA from the minor groove without any noticeable enantio-selectivity. Our results support and extend structural models based upon Norden's studies, and conflict with Barton's model.  相似文献   
430.
ZnCl2离子液体中高区域选择性合成对位柑菁醛   总被引:4,自引:0,他引:4  
 二烷基咪唑或烷基吡啶卤化物与ZnCl2构成一类新型的具有Lewis酸性的离子液体,以其为催化剂和反应介质,通过月桂烯与丙烯醛的Diels-Alder反应高区域选择性地合成了对位柑菁醛. 结果表明,与常规有机溶剂-ZnCl2催化体系相比,该体系不仅显著地加快了反应速率,而且明显提高了对位柑菁醛的区域选择性. 当ZnCl2与二烷基咪唑或烷基吡啶卤化物的摩尔比为2∶1,温度为15 ℃时月桂烯几乎可完全转化为柑菁醛,且对位柑菁醛的区域选择性p/m>18. 与氯铝酸盐离子液体相比,该离子液体对水和空气不敏感. 反应结束后,产物与离子液体自动分层,解决了传统均相催化体系中催化剂与产物不易分离的问题. 分离后的离子液体用正己烷清洗提纯后,重复使用4次,其催化活性和区域选择性基本保持不变.  相似文献   
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