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341.
Takehiko Yamato Carol Pérez Casas Hideo Yamamoto Mark R. J. Elsegood Sophie H. Dale Carl Redshaw 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):261-269
Regioselective synthesis of bis[(2-pyridylmethyl)oxy]tetrathiacalix[4]arenes was accomplished by a protection–deprotection method using benzyl groups as a protecting group. The conformational studies of distal-bis[(2-pyridylmethyl)oxy]thiacalix[4]arenes in solution and solid state are described. The two-phase solvent extraction data indicated that bis[(2-pyridylmethyl)oxy]tetrathiacalix[4]arenes show strong Ag+ (E%, 97%) affinity. In contrast, no significant E% is observed for K+. A good Job plots proves 1:1 coordination of 1,3-alternate
-3 with Ag+ cation. 1H-NMR Titration of 1,3-alternate-
3 with AgSO3CF3 also clearly demonstrates that a 1:1 complex is formed with retention of the original symmetry. The conformational changes of pyridine moiety from the original outward orientation of the ring nitrogen to the inside orientation toward the thiacalixarene cavity were observed in the process of Ag+ complexation. The down-field shifts of the benzene protons of the benzyl group were also observed and attributed to the conformational deviation from the original face to face overlapping. 相似文献
342.
Yuki Tanaka Kiichi Sato Masayuki Yamato Teruo Okano Takehiko Kitamori 《Analytical sciences》2004,20(3):411-413
A microchip-based cell response assay system to an anticancer agent was developed. The hepatoma cell line HepG2 was used to assess the effects of an anticancer agent, doxorubicin. The required cell number was reduced by two orders, and the observation of the time course of cell response became possible. The system clearly showed that treatment with higher doses of the drug or longer exposure times gave more effects to cells. The possibilities of novel drug response studies or toxicity assay system were demonstrated. 相似文献
343.
Copper(I)‐Catalyzed Enantio‐ and Diastereodivergent Borylative Coupling of Styrenes and Imines 下载免费PDF全文
Dr. Taisuke Itoh Yamato Kanzaki Dr. Yohei Shimizu Prof. Dr. Motomu Kanai 《Angewandte Chemie (International ed. in English)》2018,57(27):8265-8269
We report copper(I)‐catalyzed enantio‐ and diastereodivergent borylative coupling of styrenes and imines to produce enantiomerically‐enriched α,β‐dibranched γ‐boryl amine derivatives. Each of the four possible stereoisomers of the products, derived from the two contiguous stereocenters, was selectively accessible by choosing a proper chiral ligand for the copper catalyst. This method, which combines catalyst‐controlled stereodivergency and constitutional divergency derived from the lynchpin motif (i.e., the C?B bond), offers a strategy for addressing the construction of molecular structural diversity concomitant with precise chirality control. 相似文献
344.
Indanol‐Based Chiral Organoiodine Catalysts for Enantioselective Hydrative Dearomatization 下载免费PDF全文
Prof. Dr. Takuya Hashimoto Yuto Shimazaki Yamato Omatsu Prof. Dr. Keiji Maruoka 《Angewandte Chemie (International ed. in English)》2018,57(24):7200-7204
Rapid development in the last decade has rendered chiral organoiodine(I/III) catalysis a reliable methodology in asymmetric catalysis. However, due to the severely limited numbers of effective organoiodine catalysts, many reactions still give low to modest enantioselectivity. We report herein a solution to this issue through the introduction of a pivotal indanol scaffold to the catalyst design. Our catalyst architecture exhibits the advantage of high modularity and thereby expedites catalyst optimization. The catalyst was optimized for the challenging and highly sought‐after hydrative dearomatization of 2‐substituted phenols at the 4‐position. 相似文献
345.
Dr. Jiang‐Lin Zhao Dr. Xue‐Kai Jiang Dr. Chong Wu Dr. Chuan‐Zeng Wang Prof. Xi Zeng Prof. Carl Redshaw Prof. Dr. Takehiko Yamato 《Chemphyschem》2016,17(20):3217-3222
A series of anthracene‐containing derivatives have been synthesised and characterised. The photochemical behaviour of these derivatives have been investigated by 1H NMR spectroscopy. An unprecedented photolysis reaction for anthracene‐containing derivatives was observed in the case of anthracenes directly armed with a ‐CH2O‐R group upon UV irradiation. The photolysis reaction process has been demonstrated to occur in three steps. Firstly, the anthracene‐containing derivatives are converted into the corresponding endoperoxide intermediate upon UV irradiation in the presence of air; then, the endoperoxide intermediate is decomposed to the corresponding starting compound and 9‐anthraldehyde; finally, 9‐anthraldehyde is further oxidised to anthraquinone. Additionally, the photolysis reaction of anthracene‐containing derivatives is significantly promoted in the presence of a thiacalix[4]arene platform. 相似文献
346.
Keiko Sumitomo Takahisa Ito Motoyasu Sasaki Yoshinori Yamaguchi 《Chromatographia》2008,67(9-10):715-721
Capillary electrophoresis of crude biological samples with time-resolved fluorescence (TRF) detection enables elimination of interference from organic fluorophores and from light scattering. Because the fluorescence lifetime of biological substances and impurities overlaps the fluorescence lifetime of conventional labeling dyes, TRF detection with conventional organic labeling dyes suffers from background fluorescence. In this work, we synthesized a luminescent lanthanide chelating reagent to covalently bind the 5′-end of DNA through its dichroic functional group while retaining the unique luminescent properties of the lanthanide chelate, i.e. large Stokes shift, sharp emission, and a long luminescence lifetime in the microsecond to millisecond range. The luminescence of lanthanide chelates is inherently quenched by dissociation of the central metals in typical biological buffers containing a strong chelator, for example EDTA or phosphate; the synthesized Eu3+ chelate reagent, however, was stable even in EDTA solutions. In addition to stability in biological buffer solution, the synthesized Eu3+ chelate reagent enabled direct labeling of single-stranded oligonucleotides, and was used for DNA hybridization assay by time-resolved capillary gel electrophoresis. DNA hybridization assay in fetal bovine serum was also demonstrated. 相似文献
347.
Tanaka Y Sato K Shimizu T Yamato M Okano T Manabe I Nagai R Kitamori T 《Lab on a chip》2008,8(1):58-61
We have demonstrated the working principle of a bio-microactuator using smooth muscle cells (SMCs) by driving micropillars coupled to cultured SMCs and controlled pillar displacements by chemical stimuli; the generated driving force was estimated to be over 1.1 microN. 相似文献
348.
Thermal imprinting of transparent tin phosphate glass was performed at 250 degrees C using a fine-patterned silica mold. The glass sample was prepared by a conventional melt-quenching method and polished with a roughness of < or =10 nm for imprinting experiments. The imprinting temperature is optimized based on experimental viscosity data. Scanning electron microscope and atomic force microscope observations revealed that a square grid pattern has a surface roughness of < or =10 nm and 5 microm x 5 microm squares with ~1 microm intervals and 90-100 nm depth. Diffraction spots due to the micropattern are demonstrated by illuminating He-Ne laser light. 相似文献
349.
Yoshinori Tokuda Takeshi Irimoto Naoki Nishikawa Yutaro Katsuyama Shunsuke Kobayashi Tomoharu Tokunaga Takahisa Yamamoto 《Surface and interface analysis : SIA》2022,54(3):212-217
Herein, we investigated the surface of an (La0.3Sr0.7)(Al0.65Ta0.35)O3 (LSAT) single crystal via scanning transmission electron microscopy (STEM) after annealing in air. We found amorphous mounds and atomically flat surfaces formed on the surface of the (100) LSAT single crystal subsequent to heat treatment. These surface mounds mainly constituted SrO, including ~50 at.% Al. The atomically flat surface showed a B-site termination determined by the direct surface observation at the atomic scale through HAADF-STEM. The atomic arrangements on the surface were accommodated by surface-mound formation and La evaporation. Consequently, the ordered structure disappeared because of the increase in the Ta content at the terminated B-site layer. 相似文献
350.