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671.
High-performance thin-layer chromatography (HPTLC) is a separation technique commonly used to identify and quantify compounds in chemical mixtures. Preliminary experiments indicated that Lichrospher silica gel 60 F254s HPTLC sheets were the most suitable for analyzing vitamin B12 compounds. This study revealed the advantages of miniaturized Lichrospher HPTLC for analyzing authentic vitamin B12 compounds as short migration distances (5 cm) and short development times (<45 min) in combination with high separation efficiency and sensitivity (>25 pmol at 254 nm). The practicability of using miniaturized HPTLC was demonstrated by the separation and identification of vitamin B12 compounds purified from foods using an immunoaffinity column. 相似文献
672.
Kohei Iwai Hiroshi Yamagishi Colin Herzberger Yuji Sato Hayato Tsuji Ken Albrecht Kimihisa Yamamoto Fumio Sasaki Hiroyasu Sato Aswin Asaithambi Axel Lorke Yohei Yamamoto 《Angewandte Chemie (International ed. in English)》2020,59(31):12674-12679
Microcrystallites are promising minute mirrorless laser sources. A variety of luminescent organic compounds have been exploited along this line, but dendrimers have been inapplicable owing to their fragility and extremely poor crystallinity. Now, a dendrimer family that overcomes these difficulties is presented. First‐, second‐, and third‐generation carbazole (Cz) dendrimers with a carbon‐bridged oligo(phenylenevinylene) (COPV2) core (GnCOPV2, n=1–3) assemble to form microcrystals. The COPV2 cores align uni/bidirectionally in the crystals while the Cz units in G2‐ and G3COPV2 align omnidirectionally. The dendrons work as light‐harvesting antennas that absorb non‐polarized light and transfer it to the COPV2 core, from which a polarized luminescence radiates. Furthermore, these crystals act as laser resonators, where the lasing thresholds are strongly coupled with the crystal morphology and the orientation of COPV2, which is in contrast with the conventional amorphous dendrimers. 相似文献
673.
Fumio Hamada Yoshihiko Kondo Kyoko Ishikawa Hideaki Ito Iwao Suzuki Tetsuo Osa Akihiko Ueno 《Journal of inclusion phenomena and macrocyclic chemistry》1994,17(3):267-275
Sodium anthranilate-modified-cyclodextrin (1) has been prepared as a sensor for detecting organic compounds including terpenoids and steroids.1 shows a pure monomer fluorescence whose intensity is increased or decreased upon addition of the guest species examined. In this system, the sodium anthranilate moiety acts either as a spacer, which enables the cyclodextrin to form a 11 guest complex by narrowing the-cyclodextrin cavity or acts as a hydrophobic cap.1 shows a higher sensitivity for terpenoids than for steroids, but has a higher selective molecular recognition ablity for steroids than for terpenoids. 相似文献
674.
Mino R. Caira Luigi R. Nassimbeni Janet L. Scott Fumio Toda 《Journal of chemical crystallography》1994,24(8):545-552
The crystal structures and thermal analyses of the host compound, N,N,N,N-tetracyclohexylfumaride, witho-cresol,p-cresol and water are reported and compared to that of them-cresol complex previously reported in an attempt to elucidate the reasons for host selectivity. 相似文献
675.
The refractive indices of LiNb1?yTayO3 single crystals grown by the Czochralski method were determined in the wavelength range 5893 to 10600 Å at 20 ± 0.5°C. The results indicate that a single crystal (0.95 < y < 0.96) has zero birefringence. Such composition is independent of the wavelength. 相似文献
676.
Giseop Kwak Ken-Ichi Sumiya Fumio Sanda Toshio Masuda 《Journal of polymer science. Part A, Polymer chemistry》2003,41(22):3615-3624
Polymerization of p-(dimethylsilyl)phenylacetylene in toluene at 25 and 80 °C with RhI(PPh3)3 catalyst afforded highly regio- and stereoregular poly(dimethylsilylene-1,4-phenylenevinylene)s [cis- and trans-poly( 1a )s] containing 98% cis- and 99% trans-vinylene moieties, respectively. The trans-type polymers exhibited redshifts and hyperchromic effects in the ultraviolet–visible spectrum as compared with the cis-type counterparts. Photoirradiation of cis- and trans-poly( 1a )s gave cis-rich mixtures at equilibrium states. The trans and cis polymers exhibited different emission properties, for example—trans polymer, emissn λmax = 400 nm, quantum yield: 3.4 × 10−3 and cis polymer, emissn λmax = 380 nm, quantum yield: 1.5 × 10−3. Besides poly( 1a ), poly(dimethylsilylenearylenevinylene)s containing biphenylene and phenylenesilylenephenylene units [poly( 3 )] were prepared. The extent of conjugation in these polymers decreased in the orders of biphenylene > phenylene > phenylenesilylenephenylene as well as trans-vinylene > cis-vinylene. The quantum yield of the trans-rich polymer with biphenylene moiety was fairly large and 0.15. Polyaddition of 1,4-bis(dimethylsilyl)benzene and three types of diethynylarenes (4,4′-diethynylbiphenyl, 2,7-diethynylfluorene, and 2,6-diethynylnaphthalene) catalyzed by RhI(PPh3)3 provided novel regio- and stereoregular polymers [poly( 6 )]. These polymers displayed blue light emission with high quantum yields (4–81%). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3615–3624, 2003 相似文献
677.
Dmitry A. Kukuruznyak Jerome G. Moyer Nam T. Nguyen Edward A. Stern Fumio S. Ohuchi 《Journal of Electron Spectroscopy and Related Phenomena》2006,150(2-3):275-281
Local atomic and crystal structures around Cu and Mn atoms in Mn1.68Cu0.6Ni0.48Co0.24O4 spinel samples fabricated by metal–organic decomposition synthesis at different annealing temperatures were investigated by X-ray absorption fine structure analysis. There are two distinct copper cations, Cu1+ and Cu2+, both of which maintain tetrahedral coordination. The bond-length distances are Cu1+–O = 2.00 Å and Cu2+–O = 1.80 Å. The manganese cations are for the most part octahedral. The spinels prepared at low temperature (600 °C) contain smaller (Mn4+–O = 1.88 Å) undistorted MnO6 octahedrons corresponding to Mn4+ valence, whereas the manganese octahedrons in high-temperature materials (800 °C and higher) were larger and had a pronounced tetragonal distortion pertaining to Mn3+ oxidation state (Mn3+–O = 1.93 Å and 2.11 Å). By rising the fabrication temperatures, relative concentration of the species of Mn4+ and Mn3+ varies as a result of the reaction represented by Cu1+ + Mn4+ Cu2+ + Mn3+, implying irreversible temperature-induced structural transformation. Atomic coordinates in the low-temperature phase are similar to those found in the ideal cubic spinel with oxygen parameter u = 0.27, whereas local environments of the Cu and Mn atom correspond to the tetragonal CuMn2O4 phase (space group I41/amd). Unlike in CuMn2O4, orientation of the lattice distortions is random, however, the long-range cubic spinel structure is retained at all time. 相似文献
678.
Tadao Nozawa Fumio MorimotoRikio Harazono Norimoto Nouchi 《Journal of magnetism and magnetic materials》2006
The possibility of achieving soft magnetization in semi-hard magnetic films such as Fe, Fe93.5Si6.5, Fe50Co50 and Fe70Co30 is investigated by depositing films on an Fe20Ni80 underlayer by oblique-incidence evaporation. The magnetic anisotropy of the underlayer is strengthened to a depth of several lattice parameters by vapor deposition of the film at an oblique angle to the substrate surface. This method also allows magnetic anisotropy to be induced in strongly isotropic semi-hard magnetic overlayers to a thickness of a few thousands Angstroms. The coercive force of bilayer films measured along the hard-axis is reduced remarkably by this process, and the strength of the anisotropy field is demonstrated to be readily controllable. When magnetic anisotropy exists in both magnetic layers, a significant change is observed in the magnetization processes of the semi-hard magnetic layer and the coercive forces in the hard magnetization direction is dramatically reduced. Soft magnetization of the semi-hard magnetic layer cannot be achieved when magnetic anisotropy exists in only one of the magnetic layers. 相似文献
679.
Hiroto Sato Hideo Fujikake Hiroshi Kikuchi Taiichiro Kurita Fumio Sato 《Liquid crystals》2005,32(2):221-227
This paper describes a flexible monostabilized ferroelectric liquid crystal (FLC) device using molecularly aligned polymer walls and networks, which are sequentially formed with a two-step photopolymerization-induced phase separation. When ultraviolet (UV) light was irradiated through a photomask onto a heated nematic phase solution of FLC and monomer, monomer molecules that had flowed into the irradiated areas were photopolymerized, and polymer walls aligned along the rubbing direction of the polyimide alignment layers on plastic film substrates were formed. After uniform UV irradiation without a photomask, polymer networks aligned along the rubbing direction were formed in the FLC. The FLC molecules were monostabilized in the rubbing direction by the strong anchoring of the polymer networks. The device, which was sandwiched between crossed polarizers, exhibited a monostable electro-optic characteristic with a high contrast ratio of over 100:1 and a response time of less than 1 ms. The FLC device exhibited spatially uniform operation even when it was rolled up with a radius of curvature of 1.5 cm. 相似文献
680.
We present a diode-pumped, chirped-pulse Yb:S-FAP regenerative amplifier. This regenerative amplifier was developed as a first amplifier in an all-solid-state Yb:S-FAP laser system for laser-Compton X-ray generation. The amplifier delivers pulse energies above 24 mJ at a repetition rate of 50 Hz. Pulse compression reduces pulse widths to approximately 2.0 ps. 相似文献