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991.
Akio Toshimitsu Katsuhiro Nakano Kohei Tamao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):649-652
To prevent the racemization of the chiral carbon in the episelenonium ion intermediate bearing an aryl group on the selenium atom, both the bulky substituent(s) on the ortho position(s) of the aryl group and electron-with-drawing substituent(s) in the aryl group are found to play an important role. 相似文献
992.
Akito Takeuchi Shinobu Yamamoto Rie Narai Manami Nishida Mikio Yashiki Norihiro Sakui Akira Namera 《Biomedical chromatography : BMC》2010,24(5):465-471
A method for routinely determination of dimethyl sulfoxide (DMSO) and dimethyl sulfone (DMSO2) in human urine was developed using gas chromatography–mass spectrometry. The urine sample was treated with 2,2‐dimethoxypropane (DMP) and hydrochloric acid for efficient removal of water, which causes degradation of the vacuum level in mass spectrometer and shortens the life‐time of the column. Experimental DMP reaction parameters, such as hydrochloric acid concentration, DMP–urine ratio, reaction temperature and reaction time, were optimized for urine. Hexadeuterated DMSO was used as an internal standard. The recoveries of DMSO and DMSO2 from urine were 97–104 and 98–116%, respectively. The calibration curves showed linearity in the range of 0.15–54.45 mg/L for DMSO and 0.19–50.10 mg/L for DMSO2. The limits of detection of DMSO and DMSO2 were 0.04 and 0.06 mg/L, respectively. The relative standard deviations of intra‐day and inter‐day were 0.2–3.4% for DMSO and 0.4–2.4% for DMSO2. The proposed method may be useful for the biological monitoring of workers exposed to DMSO in their occupational environment. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
993.
994.
Kohei Sakata Kohei Tada Satoru Yamada Yasutaka Kitagawa Takashi Kawakami Shusuke Yamanaka 《Molecular physics》2014,112(3-4):385-392
Lately, it was found that the Au nanoclusters stabilised by poly(N-vinyl-2-pyrrolidone) [PVP; (C6H9ON)n], abbreviated to Au:PVP, can oxidise p-hydroxybenzyl alcohol selectively into the corresponding aldehyde in water without degradation. This observation indicates that Au cluster can exhibit high catalytic activity without any metal oxide supports. From previous works, it was found that the anionic Au clusters played an important role for the activation of oxygen molecule on the Au clusters. However, the catalytic activity of neutral Au clusters for the aerobic oxidation reaction of alcohol is not still investigated in detail. In order to examine the catalytic activity of neutral Au clusters, the aerobic oxidation of p-hydroxybenzyl alcohol to the corresponding aldehyde catalysed by Au6 has been investigated quantum chemically using density functional theory with the PBE0 functional. Possible reaction pathways are investigated taking account of full structure relaxation of the model systems. From the calculation results, it was found that the formations of both a hydroperoxyl anion and a hydride were the important steps for the aerobic oxidation of p-hydroxybenzyl alcohol over Au6 cluster. 相似文献
995.
Kohei Sanui Naoya Ogata Kazuyuki Kamitani Masayoshi Watanabe 《Journal of polymer science. Part A, Polymer chemistry》1993,31(3):597-602
Direct polycondensation of 3-substituted-4-hydroxybenzoic acid was carried out in solutions of styrene-butadiene block copolymers (SBS) at room temperature in the presence of triphenylphosphine and hexachloroethane as an initiator for the direct polycondensation of these monomers. Solution casting after the direct polycondensation provided opaque films in which the aromatic polyester was finely dispersed within the matrix of SBS. Mechanical properties of these films were examined by tensile tests. A great improvement of tensile strength was achieved by the incorporation of phenyl substituent in the resulting polyester. In-situ direct polycondensation leads to the formation of new composites of rigid polymers and flexible polymers. © 1993 John Wiley & Sons, Inc. 相似文献
996.
The119Sn—Mössbauer study on the vibrational study of some YBa2(Cu0.995·Sn0.005)3O7?γ superconductors has revealed that the ?n A?vs?T plot becomes constant below the Te(on)'s. This indicates that quenching of the Cu(1)-site vibration occurs around individual Te(on)'s of superconducting transition: 94.8, 60 and 49 K. On the contrary, the anomaly is not observed in semiconducting YBa2 (Cu0.995Sn0.005)3O7?γ (y?0.9); the vibration shows “normal” mode explained by the “combined Debye and Einstein model”. These results suggest that the slow Cu(1)-site vibration with a frequency less than 5.4×107 Hz is softened like a raman-active phonon mode (B1g) observed at 337 cm?1 in the CuO4 planars of Cu(2)O5 pyramids. 相似文献
997.
998.
Naoya Ogata Kohei Sanui Hozumi Tanaka Hajime Matsuo Fusako Iwaki 《Journal of polymer science. Part A, Polymer chemistry》1981,19(10):2609-2617
Polycondensation reactions of hydroxyl diesters such as dimethyl tartrate (DMT) and diethyl mucate (DEM) with hexamethylenediamine (HMD) were carried out in the presence of poly(vinyl pyridine) (P-VPy) and its copolymers with styrene of different compositions as matrix polymers in order to investigate the difference in interaction forces with monomers or the resulting polyamides owing to hydrogen bonding. It was found that matrix effects of poly(4-vinyl pyridine) (P-4VPy) on the rate enhancement and solution viscosity of the resulting polyamide became more pronounced with decreasing solvent polarity. This result suggests that the matrix effects of P-4VPy on polycondensation are due to hydrogen bonding interactions between hydroxyl diesters and P-4VPy. The addition of P-4VPy increased the molecular weight of the resulting polyamide to a higher extent than poly(2-vinyl pyridine) (P-2VPy), and the molecular weight of the resulting polyamide could be controlled according to the molecular weight of P-4VPy. Copolymer composition of 4-vinyl pyridine–styrene (4VPy/St) copolymers as matrix polymers also affected the molecular weight of the polyamide, which increased with increasing P-4VPy unit contents in the copolymers. 相似文献
999.
1000.
Kohei Fujiwara 《Czechoslovak Journal of Physics》2005,55(12):1639-1643
The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) is being upgraded with a novel four-layer silicon vertex
tracker. The detector will enhance the physics capabilities of PHENIX in the future phase of the heavy-ion and the polarized
proton-proton programs at RHIC. The silicon vertex tracker will allow the direct measurement of heavy quark production by
identifying displaced decay vertices, and will reconstruct jets with nearly full azimuthal coverage over |η| < 1.2. We are
developing a novel Silicon Pixel Detector for the inner two barrel layers of the silicon vertex tracker. In this paper, the
status of the development is reported.
for the PHENIX collaboration
Presented in the Poster Session “Future Experiments and Facilities” at the 18th International Conference “Quark Matter 2005”,
Budapest, Hungary, 4–9 August 2005. 相似文献