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101.
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104.
M Kobayashi N K Lee H Shibuya T Momose I Kitagawa 《Chemical & pharmaceutical bulletin》1991,39(5):1177-1184
Five tridecapeptide lactones, named theonellapeptolides Ia (1), Ib (2), Ic (3), Id (4), and Ie (5), were isolated from the Okinawan marine sponge Theonella swinhoei. Following the structure elucidation of theonellapeptolide Id (4), the structures of theonellapeptolides Ia (1), Ib (2), Ic (3), and Ie (5) were determined on the basis of chemical and physicochemical evidence including high performance liquid chromatography and circular dichroism combined analysis of the amino acid compositions. Theonellapeptolides Ib (2), Ic (3), Id (4), and Ie (5) exhibit moderate cytotoxic activity towards for L1210 in vitro (IC50 1.6, 1.3, 2.4, and 1.4 micrograms/ml, respectively), and theonellapeptolide Ie (5) exhibits ion-transport activities for Na+ and K+ ions. 相似文献
105.
Toshiki Hara Yasushi Nomura Susumu Narita Tai-ichi Shibuya 《Chemical physics letters》1995,240(5-6):610-614
The role of the low-lying two-electron excited 1Ag states of C60 in contributing to its hyperpolarizability γ is investigated by singly and doubly excited CI calculations in the semi-empirical CNDO/S approximation. It is found that inclusion of the doubly excited configurations is essential in evaluating γ. The calculated values of γzzzz(−3ω; ω, ω, ω) at wavelengths of ∞, 1.9, 1.83 μm sufficiently far from the first resonance are in reasonable agreement with experiment. 相似文献
106.
I Kitagawa R Zhang K Hori K Tsuchiya H Shibuya 《Chemical & pharmaceutical bulletin》1992,40(8):2041-2043
Two new phenylpropanoids named pongapinone A (1) and pongapinone B (2) were isolated from the bark of Pongamia pinnata (Papilionaceae), an Indonesian medicinal plant, and their chemical structures have been elucidated on the basis of their physicochemical properties. Pongapinone A (1) was found to inhibit interleukin-1 production. 相似文献
107.
Tetsuji Kametani Shoji Hirata Shiroshi Shibuya Masahisa Shio 《Journal of mass spectrometry : JMS》1971,5(2):117-122
The electron-impact induced fragmentation of twenty 3-alkyl-1-phenyl-Δ2-1,2,4-triazolin-5-ones, three 1-phenyl-1,2,4-triazolin-3,5-diones and ten 2-alkyl-4-phenyloxadiazolin-5-ones has been studied by conventional mass spectrometry. The major cleavages take place in the 1-phenyl-Δ2-1,2,4-triazolin-5-one nucleus, producing three major fragment ions. 4-Phenyloxadiazolin-5-ones exhibit a similar fragmentation pattern to 1-phenyl-Δ2-1,2,4-triazolin-5-ones. Furthermore, several additional fragmentation processes are observed in the case of specific 1,2,4-triasolines. 相似文献
108.
Takehiro YamagishiTakanori Kusano Babak KaboudinTsutomu Yokomatsu Chiseko SakumaShiroshi Shibuya 《Tetrahedron》2003,59(6):767-772
The diastereoselective synthesis of β-substituted α-hydroxyphosphinates was achieved by hydrophosphinylation of α-oxy aldehydes and α-amino aldehydes with ethyl allylphosphinate catalyzed by lithium phenoxide. 相似文献
109.
C F Tseng S Iwakami A Mikajiri M Shibuya F Hanaoka Y Ebizuka K Padmawinata U Sankawa 《Chemical & pharmaceutical bulletin》1992,40(2):396-400
N-trans- and N-cis-Feruloyltyramines were isolated as the inhibitors of in vitro prostaglandin (PG) synthesis from an Indonesian medicinal plant, Ipomoea aquatica (Convolvulaceae). In order to clarify structure activity relationships, cinnamoyl-beta-phenethylamines with possible combinations of naturally occurring cinnamic acids and beta-phenethylamines were synthesized and tested for their inhibitory activities against PG synthetase and arachidonate 5-lipoxygenase. The compounds containing catechol groups such as N-caffeoyl-beta-phenethylamine (CaP) showed higher inhibitory effects on PG synthetase. The catechol group was found to be essential for the inhibition of arachidonate 5-lipoxygenase. The investigation of concentration dependent effects on PG biosynthesis revealed that CaP enhanced PG biosynthesis at a lower concentration range, whereas it inhibited the reaction at a higher concentration. The effects of CaP on each reaction step were investigated with purified PG endoperoxide synthase and microsomal PG synthetase. CaP inhibited the cyclooxygenase reaction, while it enhanced the hydroperoxidase reaction. N-Acyldopamines which contain catechol and lipophylic group were synthesized from dopamine and fatty acids to test their inhibitory effects on arachidonate 5-lipoxygenase. N-Linoleoyldopamine was the most active compound and its IC50 value was 2.3 nM in our assay system, in which an IC50 value of AA 861, a specific inhibitor of 5-lipoxygenase, was 8 nM. 相似文献
110.
M. Fujioka S. Shibuya N. Kawamura A. Matsumoto Y. Kimura S. Hayashibe T. Ishimatsu R. Coussement M. Rots L. Hermans 《Hyperfine Interactions》1983,16(1-4):1017-1020
The time-integral angular distribution was measured as a function of an external magnetic field for -rays from the 398-keV 9/2 state of69Ge populated by bombarding a Zn single crystal with a natural -beam from a cyclotron. Clear resonances of dispersion as well as Lorentz types having a natural width (=4 s) were observed at Bres=9.14 kG corresponding to the first level-crossing resonance of the 9/2 state due to the combined collinear magnetic and electric interactions. The effects of non-collinearity were also demonstrated, and compared with theory. 相似文献