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91.
Kobayashi S Ohmae M Ochiai H Fujikawa S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(23):5962-5971
Hyaluronidase (HAase) catalyzes multiple enzymatic polymerizations with controlling regio- and stereoselectivity perfectly. This behavior, that is, the single enzyme being effective for multireactions and retaining the enzyme catalytic specificity, is not usual, and hence, HAase is a supercatalyst. Various sugar oxazoline monomers prepared based on the concept "transition-state analogue substrate" were successfully polymerized and copolymerized with HAase catalysis, yielding natural and unnatural glycosaminoglycans. 相似文献
92.
Reported here for the first time are the stereoselective synthesis and reaction of simple silver (Z)-enethiolates, which serve as stabilized (Z)-enethiol storage. In contrast to labile enethiols, silver (Z)-enethiolates are stable even in solutions, and their isolation and purification are very simple. The method for synthesis of silver (Z)-enethiolates involves an unusual vinylic SN2 reaction of (E)-vinyl-lambda3-iodanes with thiobenzamides yielding the inverted (Z)-S-vinylthioimidonium salts, followed by their regioselective C-S bond cleavage with silver acetate. Alkylation, arylation, and Michael addition of silver (Z)-enethiolates yielding (Z)-vinyl sulfides were dramatically accelerated by the addition of Bu4NI (LiI), which probably generates reactive ammonium (Z)-enethiolates with an increased nucleophilicity. 相似文献
93.
A novel selectable one-dimensional (1D) or two-dimensional (2D) gas chromatography–mass spectrometry (selectable 1D/2D GC–MS) system with selective detection was developed by using capillary flow technology and low thermal mass GC (LTM-GC). The main advantages of this system are the simple and fast selection of 1D GC–MS or 2D GC–MS operation without any instrumental set-up change (e.g.2D GC–MS can be run just after 1D GC–MS run), and simultaneous mass spectrometric and olfactometry or element-specific detection for both 1D and 2D separation to assure selection of a heart-cut region and correct identification of compounds of interest. The feasibility and benefit of the proposed system with selective detection, e.g. olfactometry, nitrogen phosphorus detection (NPD), and pulsed flame photometric detection (PFPD), was demonstrated with an identification of trace amounts of aroma components in beverages (beer and coffee). Using stir bar sorptive extraction (SBSE) and selectable 1D/2D GC–Olfactometry/MS on a beer sample, β-damascenone could be determined at 1.9 ng mL−1 (RSD 3.1%, n = 6) as a potent aroma compound. In a coffee sample, two odor active compounds were clearly resolved from a 4.2 s heart-cut and were assigned probable identifications as 4,5-dimethyl thiazole and dimethyl trisulfide based on a NIST library search, dual linear retention indices (dual LRI) and elemental information obtained by SBSE in combination with selectable 1D/2D GC–NPD/PFPD/MS. 相似文献
94.
Bungo Ochiai Shin‐Ich Sato Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3400-3407
A polyurethane bearing methacrylate groups through urethane linkages was prepared by the addition of 2‐methacryloyloxyethyl isocyanate to the hydroxyl groups in poly(hydroxyurethane) prepared by the polyaddition of a bifunctional cyclic carbonate with 1,12‐diaminododecane. The urethanization proceeded quantitatively in the presence of a catalytic amount of di‐n‐butyltin dilaurate at an ambient temperature, whereas a crosslinked product was obtained from the reaction at 60 °C. The resulting linear polyurethane, bearing a methacrylate structure, was thermally crosslinkable. Its radical copolymerization with vinyl‐type monomers afforded the corresponding crosslinked polymers, whose low glass transition temperatures suggested the flexibility of the polymer chains in the crosslinked product. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3400–3407, 2007 相似文献
95.
Ochiai M Nishi Y Hashimoto S Tsuchimoto Y Chen DW 《The Journal of organic chemistry》2003,68(20):7887-7888
In the presence of triethylamine, (Z)-(2-acetoxy-1-alkenyl)phenyl-lambda(3)-iodanes react with thioureas or thioamides in MeOH to give 2,4-disubstituted thiazoles directly in good yields. The reaction probably involves generation of highly reactive alpha-lambda(3)-iodanyl ketones through ester exchange of the beta-acetoxy group with liberation of methyl acetate, followed by nucleophilic substitutions with thioureas or thioamides. 相似文献
96.
Aryl vinyl ketones are prepared by the reaction of aryl iodides and terminal acetylenes in the presence of a catalytic amount of PdCl2(PPh3)2, Cp2TiCl2 and a stoichiometric amount of Zn-Cu under an atmospheric pressure of carbon monoxide. 相似文献
97.
Ochiai M Suefuji T Miyamoto K Shiro M 《Chemical communications (Cambridge, England)》2003,(12):1438-1439
The single crystal X-ray structure of the supramolecular complex formed between diphenyl-lambda3-iodane (Ph2IBF4) or 1-alkynyl(phenyl)-lambda3-iodane [Bu(t)CCI(Ph)BF4] and 1,10-phenanthroline indicates a hitherto unknown distorted trigonal bipyramidal geometry around iodine(III), in which 1,10-phenanthroline acts as a bidentate ligand and occupies equatorial sites. 相似文献
98.
13C Fourier transform NMR of cis and trans 5 - t - butyl - 2 - methyl - 2 - cyclohexenol, 2 -methyl - 2 - cyclohexenol and their acetates has been examined indicating that the pseudo-axial orientation of the hydroxyl and the acetoxyl group at the allylic position is favoured in 2 - methyl - 2 -cyclohexenol and its acetate. 相似文献
99.
Masahito Ochiai Kazunori MiyamotoTakashi Suefuji Motoo ShiroShigeru Sakamoto Kentaro Yamaguchi 《Tetrahedron》2003,59(51):10153-10158
Slow evaporation of a solution of 1-decynyl(phenyl)(tetrafluoroborato)-λ3-iodane and 18-crown-6 in dichloromethane-diethyl ether-hexane gave a supramolecular 1:1 complex, while 3,3-dimethyl-1-butynyl- and phenylethynyl(phenyl)(tetrafluoroborato)-λ3-iodanes afforded 2:1 complexes. Complexation with 18-crown-6 increased the thermal stability of the phenylethynyl-λ3-iodane. Solid state and solution structures of these complexes were examined by single crystal X-ray analyses, 1H and 13C NMR spectra, and cold-spray ionization MS. Binding constants were measured by 1H NMR titrations. 相似文献
100.
Ochiai M Lin YS Yamada J Misawa H Arai S Matsumoto K 《Journal of the American Chemical Society》2004,126(8):2536-2545
Reaction of the platinum(III) dimeric complex [Pt(2)(NH(3))(4)((CH(3))(3)CCONH)(2)(NO(3))(2)](NO(3))(2) (1), prepared in situ by the oxidation of the platinum blue complex [Pt(4)(NH(3))(8)((CH(3))(3)CCONH)(4)](NO(3))(5) (2) with Na(2)S(2)O(8), with terminal alkynes CH[triple bond]CR (R = (CH(2))(n)CH(3) (n = 2-5), (CH(2))(n)CH(2)OH (n = 0-2), CH(2)OCH(3), and Ph), in water gave a series of ketonyl-Pt(III) dinuclear complexes [Pt(2)(NH(3))(4)((CH(3))(3)CCONH)(2)(CH(2)COR)](NO(3))(3) (3, R = (CH(2))(2)CH(3); 4, R = (CH(2))(3)CH(3); 5, R = (CH(2))(4)CH(3); 6, R = (CH(2))(5)CH(3); 7, R = CH(2)OH; 8, R = CH(2)CH(2)OH; 9, R = (CH(2))(2)CH(2)OH; 10, R = CH(2)OCH(3); 11, R = Ph). Internal alkyne 2-butyne reacted with 1 to form the complex [Pt(2)(NH(3))(4)((CH(3))(3)CCONH)(2)(CH(CH(3))COCH(3))](NO(3))(3) (12). These reactions show that Pt(III) reacts with alkynes to give various ketonyl complexes. Coordination of the triple bond to the Pt(III) atom at the axial position, followed by nucleophilic attack of water and hydrogen shift from the enol to keto form, would be the mechanism. The structures of complexes 3.H(2)O, 7.0.5C(3)H(4)O, 9, 10, and 12 have been confirmed by X-ray diffraction analysis. A competitive reaction between equimolar 1-pentyne and 1-pentene toward 1 produced complex 3 and [Pt(2)(NH(3))(4)((CH(3))(3)CCONH)(2)(CH(2)CH(OH)CH(2)CH(2)CH(3))](NO(3))(3) (14) at a molar ratio of 9:1, suggesting that alkyne is more reactive than alkene. The ketonyl-Pt(III) dinuclear complexes are susceptible to nucleophiles, such as amines, and the reactions with secondary and tertiary amines give the corresponding alpha-amino-substituted ketones and the reduced Pt(II) complex quantitatively. In the reactions with primary amines, the once formed alpha-amino-substituted ketones were further converted to the iminoketones and diimines. The nucleophilic attack at the ketonyl group of the Pt(III) complexes provides a convenient means for the preparation of alpha-aminoketones, alpha-iminoketones, and diimines from the corresponding alkynes and amines. 相似文献