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971.
K. Suzuki M. Takahashi M. Saitoh 《Applied Physics A: Materials Science & Processing》1999,69(7):S263-S266
This paper presents for the first time experimental results which show a crucial role of the local Si-H bonding structures in Si precursors for crystallinity of polycrystalline silicon (p-Si), obtained by an excimer laser crystallization (ELC) process. This role was revealed in the distinct differences among (111) lattice plane spacings of p-Si according to deposition and dehydrogenation conditions of the precursors. It was also found that preablation behaviors, especially ebullition of the melt, are highly sensitive to the precursors. These results provide an important guide for the selection of the most adequate precursor in production, and also contribute an understanding of the mechanism of the ELC process. 相似文献
972.
Shin-Ichi Ohno Katsutoshi Furukawa Masamitsu Taguchi Hideki Namba Hiroshi Watanabe 《Radiation Physics and Chemistry》1999,55(5-6):503-506
Experimental data on the spatial distribution of the energy deposited around an energetic heavy ion, from 1 MeV proton to 5.9 MeV/n uranium ion, which have been reported in the literature were documented to obtain a scaled radial dose distribution; (β/Z*)2 D(Z*, β,t)=200 (for t=0–1), 200/t2 (for t=1tc), and 200 tc/t3 (for t>tc) where Z* and β are the effective charge and velocity relative to c, the velocity of light, of the incident ion, respectively, D the dose in unit of Gy, t the radial distance in unit of nm, tc the critical distance empirically determined.
Then, if we know the yield of any chemical reaction as a function of dose from the results of experiments using γ-radiations or fast electrons or theoretical calculations, we can calculate the probability for the yield of the chemical reaction in the system bombarded with a heavy ion of the effective charge Z* and velocity β. The results of the present calculation of the LET-values and of G(Fe3+) in the ferrous sulfate acidic solution are presented and compared with reported experimental results. 相似文献
973.
Keiko Doi-Kawano Etsuko Nishimoto Yoshiaki Kouzuma Daisuke Takahashi Shoji Yamashita Makoto Kimura 《Journal of fluorescence》2009,19(4):631-639
The steady-state and time-resolved fluorescece spectroscopy is one of the most powerful method to detect and analyze subtle
conformation change and interaction between peptide elements in protein. Phytocystatin Scb isolated from sunflower seeds includes
a single Trp residue at position 85. In an attempt to investigate the interaction of the N-terminal region of Scb with the
first and second hairpin loops by fluorescence spectroscopy of Trp residue, two Scb mutants in which single Trp locates at
position 52 and 58, respectively, and their N-terminal removed mutants were generated. The N-terminal truncation changed the
fluorescence decay kinetics of Trp52 from the triple exponential to double. Furthermore, the time-resolved fluorescence anisotropy
residue indicated that the segmental motion of Trp52 was significantly enhanced by its N-terminal truncation. In contrast,
Trp58 and Trp85 had little influence. The N-terminal successive truncations of Scb and its mutants resulted in the weaken
inhibitors to papain. These results suggested that the N-terminal region of Scb interacts with the peptide segment preceding
the first hairpin loop, thereby stabilizing the conformation of the hairpin loop structure. 相似文献
974.
975.
976.
Taichi Nakano Takashi Miyamoto Takanori Endoh Makoto Shimotani Naoki Ashida Toshishige Morioka Yutaka Takahashi 《应用有机金属化学》2004,18(2):65-67
The palladium‐catalyzed silastannation of acetylenes with tributyl(trimethylsilyl)stannane in the presence of triethylphosphite is reported for the first time. The reaction occurs at room temperature to give (Z)‐silyl(stannyl)ethenes in high yields. The protodemetallation of the resulting adducts with HCl–tetraethylammonium chloride is described first, which demonstrates that the reaction is governed only by the stability of a carbonium ion arising from the protonation to (Z)‐silyl(stannyl)ethenes rather than the hard and soft acid and base principle, i.e. the β‐cation stabilization effect (σ–π stabilization one) of a stannyl group in the carbonium ion is rather significant. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
977.
197Au and125Te Mössbauer spectroscopy has been applied for the low-temperature β-phases of Ag3AuX2 (X=S, Se, and Te). The values of I. S. and Q. S. for197Au suggest that the gold atoms, linearly coordinated by two chalcogen atoms in these phases, exist as monovalent cations. The125Te Mössbauer spectra suggest that the tellurium atoms are substantially ionic for both Ag2Te and Ag3AuTe2. The nature of X-Au-X bonds is discussed on the basis of the Mössbauer data and the bond distances. 相似文献
978.
Polycatenar materials composed of a four-aromatic-ring core, with either a bulky or end-branched perfluorinated moiety attached at one end through a methylene spacer group, and three peripheral alkoxy chains of varying length (the carbon number n = 4, 6, 8, 10, 12, 14, 16) on the other end-ring, were synthesized to investigate the roles of the chemical structure of the compositional segments in relation to liquid crystalline phase formation. It was found that a homologous series of polycatenar materials exhibited a variety of liquid crystalline phases strongly dependent on the length of the peripheral alkyl chains. Moreover it was shown that changes in the spacer group and in the structure of the perfluorinated segment had a significant influence on mesophase formation. 相似文献
979.
Satoshi Kadowaki Hiroshi Suzuki Hideaki Kobayashi 《Proceedings of the Combustion Institute》2005,30(1):169-176
The unstable behavior of cellular premixed flames induced by intrinsic instability is studied by two-dimensional unsteady calculations of reactive flows. In the present numerical simulation, the compressible Navier–Stokes equation including a one-step irreversible chemical reaction is employed. We consider two basic types of phenomena to account for the intrinsic instability of premixed flames, i.e., hydrodynamic and diffusive-thermal effects. The hydrodynamic effect is caused by the thermal expansion through the flame front; the diffusive-thermal effect is caused by the preferential diffusion of mass versus heat. A disturbance with several wavelength components is superimposed on a planar flame, and the formation of a cellular flame induced by hydrodynamic and diffusive-thermal effects is numerically simulated. After the cellular-flame formation, the combination and division of cells are observed. The behavior of cellular-flame fronts becomes more unstable when the Lewis number is lower than unity, since the diffusive-thermal effect has a great influence on the unstable behavior. The cell size changes with time, and its average is greater than the critical wavelength and becomes smaller by decreasing the Lewis number. The flame velocity of cellular flames depends strongly on the length of computational domain in the direction tangential to the flame front. As the length of computational domain increases, the flame velocity becomes larger. This is because the long-wavelength components of disturbances play an important role in the shape of cellular flames, i.e., in the flame-surface area. 相似文献
980.
M Tanaka M Takahashi E Kuwahara O Koyama K Ohkubo T Yotsuyanagi 《Chemical & pharmaceutical bulletin》1992,40(6):1559-1562
The effects of dipotassium glycyrrhizinate (GLYK) on the dissolution behavior and bioavailability of amphotericin B (AMB) were investigated. The mixtures of AMB and GLYK were prepared at different molar ratios by lyophilization. Lyophilization resulted in amorphous AMB either alone or in the mixture. Dissolution rates of AMB of the mixtures were markedly faster than that of lyophilized AMB alone, which was followed by a decrease of dissolution. The initially-enhanced dissolution rate was likely to be due to the improvement of surface wettability of drug particles with GLYK rather than the amorphous state of AMB. A phase solubility study of AMB with GLYK indicated that the increasing solubility was caused by micellar solubilization. The in vitro release rate of AMB from suppositories containing the lyophilized mixtures was significantly accelerated by increasing the amount of GLYK. The rectal absorption of AMB from suppositories containing either the drug alone, a physical mixture or a lyophilized mixture was studied using rabbits. The absorption of the mixture (AMB/GLYK = 1/9) was about 35 times greater in the area under the serum concentration-time curve (0-24 h) than that of lyophilized AMB alone. These results suggest that GLYK is useful for improving the dissolution property of AMB and the bioavailability of the drug incorporated in suppositories. 相似文献