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131.
Yasuhiro Tanoue Akari Hara Norihisa Kai Kazunori Sakata Mamoru Hashimoto Takeshi Nagai 《Journal of heterocyclic chemistry》2007,44(5):1135-1137
The synthetic scheme of 6,6′‐dibromoindirubin ( 2 ) was investigated in detail. The reaction of 6‐fluoro‐3‐acetoxyindole ( 7 ) with isatin ( 8 ) in methanol with Na2CO3 produced 6′‐fluoroindirubin in moderate yields. Its structure determination was mainly undertaken using 1H NMR spectroscopy. On the basis of this result, the synthetic scheme of 2 reported by Cooksey was revised. 相似文献
132.
An investigation was carried out on decay time of the 2.09 eV emission of S2–vacancy pair centers in NaCl crystals. When the crystal was excited by a pulsed 337 nm light from an N2 laser, the 2.09 eV yellow luminescence principally decayed with the lifetime of 14.2 μs at low temperatures, and exhibited a weak thermal quenching with an activation energy of 51.3 meV above about 150 K. Such S2--vacancy pair centers responsible for the 2.09 eV luminescence were thermally stable at room temperature, and not bleached even when exposed to ultraviolet lights below about 5 eV. Thus, the 2.09 eV emission center possibly can be used as a solid-state laser active center working at room temperature. 相似文献
133.
There has been a great demand in the field of kitchen appliances to develop transparent water repellent films which have high heat-resistance around 300°C. However, those films have not been obtained by conventional sol–gel methods. In this paper, we propose a new method for fabricating transparent water repellent films with high heat-resistance using the sol–gel method, in which silicon or germanium substrates were coated with a solution including tetraethoxysilane (Si(OC2H5)4) and (2-perfluorooctyl)ethyltrimethoxysilane (CF3(CF2)7C2H4Si(OCH3)3), followed by ‘ammonia-treatment' and annealed at 300°C. The contact angles of water on the ammonia-treated film maintained its initial value, 110° after the heat treatment at 300°C for 250 h while those on the untreated film decreased to 70°, indicating that the ammonia-treatment improves heat-resistance on the film. The mechanism of ammonia-treatment was inferred from FT-IR results; the ammonia-treatment should accelerate hydrolysis and polymerization of FAS and TEOS molecules, resulting in high density of siloxane bonds between FAS and silica glass. These bonds suppress the evaporation of FAS molecules from the film during the heat treatment at 300°C, thus the film has high heat-resistance. 相似文献
134.
To clarify the kinetics and mechanisms of o/w microemulsion polymerization, the o/w microemulsion polymerizations of styrene were carried out with different kinds and types of initiators and surfactants. The number of polymer particles and the molecular weight of polymer formed were not affected by the kinds and types of initiators and surfactants. The rate of polymerization with different kinds of azo-type oil-soluble initiators with widely different water-solubility was almost the same, but was much lower than that with KPS. A kinetic model proposed by us could mostly explain the kinetic behavior except for the difference in the polymerization rate with KPS and that with oil-soluble initiators. 相似文献
135.
136.
Yu Chen Zu-En Huang Rui-Fang Cai Bo-Cheng Yu Osamu Ito Jun Zhang Wei-Wen Ma Chao-Fan Zhong Li Zhao Yu-Fen Li Lei Zhu Mamoru Fujitsuka Akira Watanabe 《Journal of Polymer Science.Polymer Physics》1997,35(8):1185-1190
The phenomena of aggregation and coalescence of fullerenes in the UV-laser ablation time-of-flight mass spectrometric investigation of C60-modified poly(N-vinylcarbazole) both in the positive and in the negative ion channels have been observed. The results indicate that in C60 chemically modified PVK (C60–PVK) copolymer the nascent fullerene fragments ruptured from main chain can easily coalesce into large fullerenes through collisions, whereas in the C60-doped PVK the aggregation and coalescence of C60 were relative weak due to nonbounding action and incomplete charge transfer behavior between C60 and PVK. Furthermore, the photoinduced electron transfer behavior between C60 and carbazole units in the C60 chemically modified poly(N-vinylcarbazole) in benzonitrile by laser flash photolysis at 355 nm has also been investigated. Efficiency of the anion radical of C60 in copolymer at 1080 nm is higher than that of the C60-doped poly(N-vinylcarbazole) polymers. The formation of a C60 radical anion may be ascribed to photoinduced electron transfer between C60 pendanted on the main chain backbone and the inter-, and intrachain carbazole units in the copolymer. © 1997 John Wiley & Sons, Inc. 35 : 1185–1190, 1997 相似文献
137.
Fumiko Kimura Tsunehisa Kimura Akira Sugisaki Mamoru Komatsu Hiroaki Sata Eiko Ito 《Journal of Polymer Science.Polymer Physics》1997,35(16):2741-2747
In situ Fourier transform infrared (FTIR) measurements were carried out to elucidate conformation changes occurring during the isothermal melt crystallization of poly(ethylene-2,6-naphthalate) (PEN). Based on the band assignments for the components of the amorphous, α-crystal form, and β-crystal form of PEN in film samples, the in situ data was analyzed in terms of the amorphous- and crystal-trans conformations. It was observed at a higher isothermal crystallization temperature that the formation of amorphous-trans conformations precedes the growth of crystals. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2741–2747, 1997 相似文献
138.
139.
The photopatternability of various silyl hydride containing organosilicone resins containing the photobase generators N‐methylnifedipine or O‐(2‐nitrobenzyl)‐N‐octyl carbamate have been examined, with the goal of identifying potential photopatternable compositions with high thermal stability after cure. Two different categories of silicone resins have been prepared from combinations of diphenylsiloxane and methyl and hydrogen silsesquioxane units and a combination of phenyl and hydrogen silsesquioxane monomer units. The photobase generators were incorporated into these resins at concentrations up to 10 weight percent. UV‐irradiation of micrometer thick silicone resin‐photobase films through a photomask, under an air atmosphere, yielded micrometer scale features after development. Photopatternable compositions have been identified with photosensitivities of less than 50 mJ/cm2. The photopatterning process is believed to proceed by base‐catalyzed reaction of resin‐based silanol groups with neighboring silyl hydride groups to yield thermally stable siloxane crosslinks. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
140.