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991.
992.
《Tetrahedron: Asymmetry》2005,16(7):1393-1402
A series of chiral α-substituted cyclohexanones have been synthesized from chemoenzymatically produced chlorocyclohexadienediol. These highly functionalized ketones can be used in the total synthesis of diverse natural products, such as bengamides. A study of the reactivity of α-chlorooxiranes, common intermediates in the synthetic scheme, showed that under nucleophilic opening conditions an intermediate chloroketone may or may not form, depending on the nature of the nucleophiles present in the reaction medium. The stereochemical outcome of this reaction is presented. 相似文献
993.
《European Journal of Operational Research》2005,161(1):32-41
In most manufacturing and distribution systems, semi-finished jobs are transferred from one processing facility to another by transporters such as Automated Guided Vehicles, robots and conveyors, and finished jobs are delivered to warehouses or customers by vehicles such as trucks.This paper investigates two-machine flow shop scheduling problems taking transportation into account. The finished jobs are transferred from the processing facility and delivered to customers by truck. Both transportation capacity and transportation times are explicitly taken into account in these models. We study the class of flow shop problems by analysing their complexity. For the makespan objective function, we prove that this problem is strongly NP-hard when the capacity of a truck is limited to two or three parts with an unlimited buffer at the output of the each machine. This problem with additional constraints, such as blocking, is also proven to be strongly NP-hard. 相似文献
994.
Yi Ma Zhaohui Wang Min Zhang Zhihao Han Dan Chen Qiuyun Zhu Weidong Gao Prof. Dr. Zhiyu Qian Prof. Dr. Yueqing Gu 《Angewandte Chemie (International ed. in English)》2016,55(10):3304-3308
A molecular beacon‐based drug delivery system was designed for both detection of telomerase activity in living cells and telomerase‐triggered drug release for precise cancer treatment. This system is composed of a gold nanoparticle core densely packed with FITC‐labeled hairpin DNA sequences hybridized with telomerase primers. Molecules of the anticancer drug doxorubicin were intercalated into the stem region of the DNA sequence. The presence of telomerase will elongate the primers, leading to inner chain substitution followed by the release of the FITC fluorescence and the trapped doxorubicin. This molecular beacon could specifically distinguish tumor cells and normal cells based on telomerase activity, precisely release doxorubicin in response to telomerase activity in the tumor cells, and prevent toxicity to normal organs. 相似文献
995.
996.
We demonstrate a simple and cost-effective programmable aperture microscope to realize multi-modal computational imaging by integrating a programmable liquid crystal display (LCD) into a conventional wide-field microscope. The LCD selectively modulates the light distribution at the rear aperture of the microscope objective, allowing numerous imaging modalities, such as bright field, dark field, differential phase contrast, quantitative phase imaging, multi-perspective imaging, and full resolution light field imaging to be achieved and switched rapidly in the same setup, without requiring specialized hardwares and any moving parts. We experimentally demonstrate the success of our method by imaging unstained cheek cells, profiling microlens array, and changing perspective views of thick biological specimens. The post-exposure refocusing of a butterfly mouthpart and RFP-labeled dicot stem cross-section is also presented to demonstrate the full resolution light field imaging capability of our system for both translucent and fluorescent specimens. 相似文献
997.
998.
以二甲酰亚胺钾3a~3g与2-氯-5-氯甲基吡啶的N原子氧化后得到的2-氯-1-氧-5-氯甲基吡啶发生亲核取代反应, 用传统和微波两种方法合成了7种未见文献报到的化合物N-(2-氯-1-氧-5-吡啶甲基)二甲酰亚胺类化合物4a~4g. 对比两种合成方法, 在常压下, 微波辐射作为反应热源具有用时少、环境友好、易纯化和产率高的特点. 这些目标化合物4a~4g的结构经元素分析结果, IR, GC-MS, 1H NMR, 13C NMR确证. 初步的生物活性测定结果表明, N-(2-氯-1-氧-5-吡啶甲基)二甲酰亚胺类部分化合物具有良好的杀虫活性. 相似文献
999.
3-甲基吡唑-5-甲酸基Zn(Ⅱ)配合物的合成、晶体结构及荧光性质 总被引:2,自引:0,他引:2
A transition metal complex Zn(mpc)2(H2O)2 (Hmpc=3-methylpyrazole-5-carboxylic acid) has been synth-esized by the reaction of Hmpc with Zn(NO3)2·6H2O using hydrothermal method, which was characterized by IR spe-ctra, elemental analysis and single-crystal X-ray structure analysis. The structure reveals that the complex crystallizes in the trigonal space group R3c with the ZnⅡ atom on a threefold axis, composed of one ZnⅡ atom, two independent mpc- ligands and two coordinated water. Hydrogen bonds link the molecules into a three-dimensional supramolecular architecture. Fluorescent analysis in the dilute EtOH solution shows that the title complex exhibits a broad fluorescent band at 471 nm upon photoexcitation at 280 nm and has a bathochromic shift of the emission energy compared with the free ligand, possibly due to metal-to-ligand charge transfer (MLCT). CCDC: 682402. 相似文献
1000.
Self-organized TiO2 nanotube arrays with micro-scale length were prepared on fluorine-doped tin oxide (FTO) conducting glass in NH4F/glycerol electrolyte by electrochemical anodization of pure titanium films deposited by radio frequency magnetron sputtering (RFMS) at room temperature. The samples were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and photoelectrochemistry methods. The results showed that Ti films prepared at the condition of Ar pressure 0.5 Pa, power 150 W, and 0.5 h at room temperature possessed the zone T model structure with good homogeneity and high denseness. When the anodization time was prolonged from 1 to 3 h at the voltage of 30 V, the pore diameter of TiO2 nanotubes increased from 50 to 75 nm, and the length increased from 750 to 1100 nm and then gradually decreased to 800 nm, while their wall morphology changed from smooth to rough. Also with increasing the anodization voltage, the pore diameter became larger, and the remaining oxide layer reduced, which could be easily removed by ultrasonic-chemical cleaning in 0.05% (w, mass fraction) diluted HF solution. Moreover, the photocurrent response curves and electrochemical impedance spectroscopy (EIS) results indicated that UV-illumination clearly enhanced the effective separation of the electron-hole pairs and the crystallized electrodes from the annealing treatment of as-anodized electrodes at 450 °C exhibited a better photoelectrochemical performance. 相似文献