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81.
Exposure of 3-phenylpropyl ethers to an activated iodosylbenzene monomer·18-crown-6 complex [PhI(OH)BF(4)·18C6] in the presence of BF(3)-Et(2)O and water results in the para-selective monofluorination of benzene ring via neighboring alkoxy group participation and directly affords 3-(4-fluorophenyl)propyl ethers regioselectively in good yields. 相似文献
82.
Makoto Obata Yurie Tanaka Naoko Araki Shiho Hirohara Shigenobu Yano Kazunori Mitsuo Keisuke Asai Masafumi Harada Toyoji Kakuchi Chikara Ohtsuki 《Journal of polymer science. Part A, Polymer chemistry》2005,43(14):2997-3006
Pressure‐sensitive paint (PSP), which consists of luminescent molecules embedded in an oxygen‐permeable polymer, has been developed for use in wind‐tunnel experiments. To improve the PSP technique, a novel luminescent methacrylate monomer, 5‐[4‐(2‐methacryloyloxyethoxycarbonyl)phenyl]‐10,15,20‐triphenylporphinato platinum(II), was synthesized and copolymerized with isobutyl methacrylate and 2,2,2‐trifluoroethyl methacrylate to produce a dye‐pendant copolymer ( 2 ). The introduction of 5,10,15,20‐tetraphenylporphinato platinum(II) (PtTPP) dye into 2 was confirmed by ultraviolet–visible spectroscopy and extended X‐ray absorption fine structure measurements. The extent of PtTPP dye incorporation in 2 was proportional to the molar fraction of the PtTPP‐pendant methacrylate monomer in the feed. The oxygen‐sensing property of 2 was compared with that of a PSP consisting of PtTPP dye embedded in poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate). Although the simple mixture of PtTPP and poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate) showed a marked deviation from a single Stern–Volmer relation, novel copolymer 2 gave a highly linear Stern–Volmer plot. This was unequivocal evidence of dye conjugation on the oxygen‐sensing polymer film. © 2005Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2997–3006, 2005 相似文献
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85.
Toshihiko Nagamura Kazunori Fukitani Motowo Takayanagi 《Journal of Polymer Science.Polymer Physics》1975,13(8):1515-1532
The micromechanism of tensile deformation of poly[p-(2-hydroxyethoxy)benzoic acid] fibers is discussed on the basis of a detailed esr study of radical formation. The concentration of primary phenoxy radicals, which were detected during deformation at room temperature as a direct indicator of main-chain rupture, was determined by extrapolating the radical decay curves at various strains to zero time. The relation between the initial radical concentration and the strain is well expressed by the cumulative normal distribution curve. By use of this relation and a model of fiber structure, the distribution of the contour length of tie chains was determined. No radicals were detected during a second stretching cycle until the maximum strain in the first run was exceeded. The deformation model which includes alternating crystalline and amorphous regions connected by tie chains, a distribution of contour lengths of tie chains, and a phase transformation of molecular chains in the crystalline region accounted fairly well for the observed stress–strain behavior of monofilaments in first and second stretching cycles. The comparison between the observed and the calculated radical concentration suggests that statistical factors and other deformation mechanisms have to be taken into account. 相似文献
86.
Kiyoshi Tanaka Tomoya Okada Fumio Yoneda Tomohisa Nagamatsu Kazunori Kuroda 《Tetrahedron letters》1984,25(16):1741-1742
1,5-Dihydro-5-deazaflavin derivatives possessing a chiral substituent at N(3) position were synthesized, with which moderate asymmetric induction was observed in the reduction of ethyl benzoylformate. 相似文献
87.
Maeda Y Miyashita J Hasegawa T Wakahara T Tsuchiya T Feng L Lian Y Akasaka T Kobayashi K Nagase S Kako M Yamamoto K Kadish KM 《Journal of the American Chemical Society》2005,127(7):2143-2146
The chemical reduction and oxidation of M@C82 (M = Y, La, and Ce) afford the corresponding anion and cation, respectively, which show unique and interesting chemical reactivities. It is found that the successful reversible gain or loss of electrons by ionization is useful for controlling the stability and reactivity of M@C82 toward both nucleophiles and electrophiles. 相似文献
88.
Ochiai M Takeuchi Y Katayama T Sueda T Miyamoto K 《Journal of the American Chemical Society》2005,127(35):12244-12245
Reported here for the first time is the iodobenzene-catalyzed alpha-oxidation of ketones, in which diacyloxy(phenyl)-lambda3-iodanes generated in situ act as real oxidants of ketones and m-chloroperbenzoic acid serves as a terminal oxidant. Oxidation of a ketone with m-chloroperbenzoic acid in acetic acid in the presence of a catalytic amount of iodobenzene, BF3.Et2O, and water at room temperature under argon affords an alpha-acetoxy ketone in good yield. p-Methyl- and p-chloroiodobenzene also serve as efficient catalysts in this direct oxidation. We found that when the reaction was carried out in the absence of a catalytic amount of iodobenzene, Baeyer-Villiger oxidation of a ketone took place. It is noted that use of water and BF3.Et2O is crucial to the success of this alpha-acetoxylation. 相似文献
89.
The method of measuring f(I) values is proposed as a measure of the adsorption capacity of adsorbents. The f(I) value, a characteristic figure for a particular system, can be obtained chromatogiaphically by measuring the progression rate of zone and the degree of packing of the column. For a system involving a unit concentration of trasns-p-methoxyazobenzene in benzene as standard solution and alumina as adsorbent, optimum conditions for the measurement of f(I) were established. The effects of day-light, pretreatment of column, temperature, flow rate of solution, amount of adsorbent and degree and mode of packing were studied Under optimum conditions, the value of f(I) was reproducible within ±2%. 相似文献
90.
The structure of the 1,3,4,6-tetrakis(isopropylthio)thieno[3,4-c]thiophene dication ( 2 ) prepared from 1,3,4,6-tetrakis(isopropylthio)thieno[3,4-c]thiophene ( 1 ) by two-electron oxidation was investigated by X-ray crystallographic analysis. The results revealed that the positive charges are largely delocalized on the two i-PrS-C-C-C-SPr-i moieties. 相似文献