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591.
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Complementary asymmetric alkylation reaction of the lithioenamine derived from 2-methoxycarbonylcyclohexanone and ()-valine -butyl ester was examined by employing the various electron pair donating additives in a toluene solvent, in order to clarify the factors controlling the diastereoface selectivity. 相似文献
594.
Kenji Nina Yuki Kimura Kaori Yokoyama Osamu Kido Gong Binyo Chihiro Kaito 《Physica E: Low-dimensional Systems and Nanostructures》2008,40(9):2995-2998
The formation process of MoO2 crystal from amorphous MoO3 film has been imaged by in situ observation with a transmission electron microscope. Selective growth of flower-shaped MoO2 crystals by heating above 673 K in vacuum was directly observed. Since the MoO2 crystal has metallic conductivity of the order of indium oxide film containing tin (ITO film), the thin film growth of the MoO2 phase has been discussed on the basis of a new substitute for ITO film. 相似文献
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We propose a novel method to fabricate a vertical alignment (VA) of liquid crystal (LC) molecules without using a conventional alignment layer such as polyimide film. The method produces the vertical alignment polymer layer (VAPL) by polymerisation of a monomer or mixed monomers including in the LC layer above TNI of the LC material. The VA mode LC cell with the VAPL (VAPL-LC cell) produced from the mixed monomers of acrylic acid 4-(4?-octyloxy-biphenyl-4-yloxy)-butyl ester and 1,2-bis-(4-methacryloxy-phenyl)-2,2-dimethoxy-ethane-1-one exhibited enough level of alignment state and electro-optical property with high voltage holding ratio. We can expect that the VAPL-LC cell is useful for next-generation displays such as flexible liquid crystal displays because the method does not need the process including high temperature over 200°C. 相似文献
597.
Isao Fujii Makoto Hashimoto Kaori Konishi Akiko Unezawa Haruka Sakuraba Kenta Suzuki Harue Tsushima Miho Iwasaki Satsuki Yoshida Akane Kudo Rina Fujita Aika Hichiwa Koharu Saito Takashi Asano Jun Ishikawa Daigo Wakana Yukihiro Goda Ayumi Watanabe Mamoru Watanabe Yui Masumoto Junichiro Kanazawa Hajime Sato Masanobu Uchiyama 《Angewandte Chemie (International ed. in English)》2020,59(22):8464-8470
Shimalactones A and B are neuritogenic polyketides possessing characteristic oxabicyclo[2.2.1]heptane and bicyclo[4.2.0]octadiene ring systems that are produced by the marine fungus Emericella variecolor GF10. We identified a candidate biosynthetic gene cluster and conducted heterologous expression analysis. Expression of ShmA polyketide synthase in Aspergillus oryzae resulted in the production of preshimalactone. Aspergillus oryzae and Saccharomyces cerevisiae transformants expressing ShmA and ShmB produced shimalactones A and B, thus suggesting that the double bicyclo‐ring formation reactions proceed non‐enzymatically from preshimalactone epoxide. DFT calculations strongly support the idea that oxabicyclo‐ring formation and 8π‐6π electrocyclization proceed spontaneously after opening of the preshimalactone epoxide ring through protonation. We confirmed the formation of preshimalactone epoxide in vitro, followed by its non‐enzymatic conversion to shimalactones in the dark. 相似文献
598.
Daisuke Uraguchi Yuto Tsuchiya Tsuyoshi Ohtani Takafumi Enomoto Shigeyuki Masaoka Daisuke Yokogawa Takashi Ooi 《Angewandte Chemie (International ed. in English)》2020,59(9):3665-3670
Unlike carbonyl compounds, it has long been common understanding that excited imines show virtually no photoreactivity, and hence their properties and potential utility in chemical science remain largely unexplored. Now, a strategy is presented for eliciting latent photoreactivity of imines based on the introduction of a donor–acceptor (D‐A) structure to extend the lifetime of their photoexcited states. A series of spectroscopic analyses and density functional theory calculations reveal unique photophysical properties of the D‐A‐type imines. Furthermore, the reactivity of the D‐A‐type imines is demonstrated by using them as a photoredox catalyst for atom‐transfer radical addition. These findings illuminate a previously neglected chemical space in the field of photochemistry, which will be exploited by taking advantage of the inherent structural modularity of imines. 相似文献
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600.
Mizuno T Murao K Tanabe Y Oda M Tanaka T 《Journal of the American Chemical Society》2007,129(37):11378-11383
Coordination of metal ions significantly contributes to protein structures and functions. Here we constructed a fusion protein, consisting of a de novo designed, metal-ion-binding, trimeric coiled-coil and a circularly permutated green fluorescent protein (cpGFP), where the fluorescent emission from cpGFP was induced by metal ion coordination to the coiled-coil. A circularly permutated GFP, (191)cpGFP(190), was constructed by connecting the original N- and C-termini of GFP(UV) by a GGSGG linker and cleaving it between Asp(190) and Gly(191). The metal-ion-binding coiled-coil, IZ-HH, was designed to have three alpha-helical structures, with 12 His residues in the hydrophobic core of the coiled-coil structure. IZ-HH exhibited an unfolded structure, whereas it formed the trimeric coiled-coil structure in the presence of divalent metal ions, such as Cu(2+), Ni(2+), or Zn(2+). The fusion protein (191)cpGFP(190)-IZ-HH was constructed, in which (191)cpGFP(190) was inserted between the second and third alpha-helices of IZ-HH. Escherichia coli cells, expressing (191)cpGFP(190)-IZ-HH, exhibited strong fluorescence when the Cu(2+) and Zn(2+) ions were present in the medium, indicating that they passed through the cell membrane and induced the proper folding of the (191)cpGFP(190) domain. This strategy, in which protein function is regulated by a metal-ion-responsive coiled-coil, should be applicable to the design of various metal-ion-responsive, nonnatural proteins that work both in vitro and in vivo. 相似文献