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71.
72.
73.
Selective introducing of aryl and amino groups: reaction of benzanthrone and organometallic reagents
Rui Umeda Teruaki Namba Tomohiro Yoshimura Masamichi Nakatsukasa Yutaka Nishiyama 《Tetrahedron》2013,69(5):1526-1531
The reaction of benzanthrone and aryl magnesium bromides produced 6-aryl-substituted benzanthrones in moderate to good yields. Similarly, 6-alkylaminobenzanthrones were selectively prepared by the reaction of benzanthrone and lithium alkylamides. In contrast, for the lithium arylamides, the arylamino groups were selectively introduced at the 4-position of the benzanthrone. 相似文献
74.
Seiji Takahashi Masamichi Tsukagoshi Yuki Kitahara Márta Juhász Toshihiro Fujii 《Rapid communications in mass spectrometry : RCM》2010,24(17):2625-2630
We designed a simple evolved gas analysis (EGA) system to act as a sampler between solid samples at atmospheric pressure and the high vacuum inside a mass spectrometer. The newly designed stainless steel system is simple, small and rugged and fulfills all the basic requirements for EGA. The temperature is programmable with 60°C/min as the maximum heating rate and the temperature range is up to 600°C. With this system coupled with lithium ion attachment mass spectrometry (IAMS), it is possible to study the temperature‐programmed decomposition of a number of solid materials by detecting any chemical species on a real‐time basis. For illustrative purposes, EGA‐IAMS experiments of polyethylene polymers have been conducted. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
75.
Yuusaku Yokoyama Masamichi Nakakoshi Hiroaki Okuno Yohko Sakamoto Satoshi Sakurai 《Magnetic resonance in chemistry : MRC》2010,48(10):811-817
The reaction mechanism for the biomimetic synthesis of tryptophan from indole and serine in the presence of Ac2O in AcOH was investigated. Although the time‐course 1H‐NMR spectra of the reaction of 5‐methoxyindole with N‐acetylserine were measured in the presence of (CD3CO)2O in CD3CO2D, the reactive intermediate could not be detected. This reaction was conducted without 5‐methoxyindole in order to elucidate the reactive intermediate, but the intermediate could not be isolated from the reaction mixture. Since the intermediate would be expected to have a very short life time, and therefore be very difficult to detect by conventional analytical methods, the structure of the intermediate was elucidated using a 2D‐NMR technique, diffusion‐ordered spectroscopy (DOSY). Two intermediates were detected and confirmed to be 2‐methyl‐4‐methyleneoxazol‐5(4H)‐one and 2‐methyl‐4‐hydroxymethyloxazol‐5(4H)‐one. The present results demonstrated that DOSY is a powerful tool for the detection of unstable intermediates. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
76.
Stepwise application of the Pd-catalyzed S(N)2' reaction and the desilylative S(E)2' reaction to the ambivalent 2-bromo-1-silyl-1,3-dienes provides a novel route to the highly enantioselective construction of tertiary and quaternary propargylic stereogenic centers via axially chiral allenylsilanes. 相似文献
77.
78.
Species desorbing from indium oxides under exposure to atomic hydrogen (H) were observed with a quadrupole mass spectrometer. The desorption of InOH was detected at a temperature as low as 410°C, which is in contrast with the fact that, with molecular hydrogen, a much higher temperature (850°C) was required to generate InOH. Upon the interruption of H generation, the InOH signal disappeared immediately, suggesting that H is involved in the reactions leading to InOH desorption. Relevance to the low-temperature cleaning of an InP surface with H is discussed. 相似文献
79.
Morita M Koga T Otsuka H Takahara A 《Langmuir : the ACS journal of surfaces and colloids》2005,21(3):911-918
Micropatterned fluoroalkylsilane monolayer surfaces with liquidphilic/liquidphobic area (line width 1-20 microm) were prepared with few defects by vacuum ultraviolet (VUV) photolithography. The anisotropic wetting of a macroscopic droplet with a 0.5-5 mm diameter on the micropatterned surfaces was investigated. The strong anisotropy of the contact angle and the sliding angle and droplet distortion for fluoroalkylsilane/silanol patterned surfaces was attributed to the difference in the energy barrier of wetting between parallel and orthogonal lines. The wetting anisotropy decreased with decreases in the liquidphilic area. Fluoroalkylsilane/alkylsilane patterned surfaces with small differences in the surface free energies of the components showed anisotropic wetting only for the low-surface-tension liquids. 相似文献
80.
Sadahito Aoshima Hideshi Onishi Masamichi Kamiya Kenji Shachi Eiichi Kobayashi 《Journal of polymer science. Part A, Polymer chemistry》1994,32(5):879-887
In the living cationic polymerization of isobutyl vinyl ether (IBVE) by the CH3CH (OiBu) OCOCH3 ( 1 )/EtAlCl2 initiating system in the presence of the added base in hexane at +40°C, the stability of the initiating system 1 /EtAlCl2, which form initiating species CH3CH⊕ (OiBu) derived from 1 , was investigated. In the presence of the Lewis base such as ethyl acetate or 1,4-dioxane, the active species was stable for 300 min even at +40°C in the absence of IBVE, and the living polymers were quantitatively obtained by adding IBVE. However, the active species was partly consumed by side reactions during the standing time for 60 min in the presence of a less basic additive such as ethyl benzoate, and about 50% of the active species was deactivated in the presence of methyl chloroacetate. Consequently, in the case of a less basic additive such as methyl chloroacetate (which was effective for the fast living polymerization), it can be seen that the careful selection of polymerization conditions was required. The living polymerization rate was dependent on the second order of EtAlCl2 concentration. EtAlCl2 induced the cleavage of 1 into CH3CH⊕ (OiBu) and EtAl?Cl2(OCOCH3), and the reactivity of CH3CH⊕ (OiBu) and propagating carbocation may be controlled by EtAl?Cl2(OCOCH3) with the aid of other EtAlCl2. Et1.5AlCl1.5 exists as a bimetallic complex of EtAlCl2 and Et2AlCl, and it is expected that the polymers having a bimodal molecular weight distribution will be obtained due to two kinds of counteranions coming from EtAlCl2 and Et2AlCl. However, in the cationic polymerization of IBVE by 1 /Et1.5AlCl1.5 in the presence of ethyl acetate, the living polymer exhibiting a unimodal and very narrow molecular weight distribution was obtained. Thereby, it was suggested that the counteranions, EtAl?Cl2(OCOCH3) and Et2Al?Cl(OCOCH3), exchange rapidly with each other. © 1994 John Wiley & Sons, Inc. 相似文献