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41.
Borovkov VV Lintuluoto JM Hembury GA Sugiura M Arakawa R Inoue Y 《The Journal of organic chemistry》2003,68(19):7176-7192
The complexation behavior, binding properties, and spectral parameters of supramolecular chirality induction in the achiral host molecule, syn (face-to-face conformation) ethane-bridged bis(zinc porphyrin), upon interaction with chiral bidentate guests (diamines and amino alcohols) have been studied by means of UV-vis, CD, fluorescence, (1)H NMR, and ESI MS techniques. It was found that the guest structure plays a decisive role in the chirogenesis pathway. The majority of bidentate ligands (except those geometrically unsuitable) exhibit two major equilibria steps: the first guest ligation leading to formation of the 1:1 host-guest tweezer structure (K(1)) and the second guest molecule ligation (K(2)) forming the anti bis-ligated species (1:2). The second ligation is much weaker (K(1) > K(2)) due to the optimal geometry and stability of the 1:1 tweezer complex. The enhanced conformational stability of the tweezer complex ensures an efficient chirality transfer from the chiral guest to the achiral host, consequently inducing a remarkably high optical activity in the bis-porphyrin. 相似文献
42.
The HO2 uptake coefficients (γ) for organic submicron aerosol particles were measured using an aerosol flow tube coupled with a chemical conversion/laser‐induced fluorescence technique under ambient conditions (760 Torr and 296 ± 2 K) and different values of relative humidity (RH) (28% and 68%). Determined uptake coefficients for succinic, glutaric, adipic, and pimelic acid aerosol particles at 28% RH were 0.07 ± 0.02, 0.07 ± 0.03, 0.02 ± 0.01, and 0.06 ± 0.03, respectively, whereas the γ values for those particles at 68% RH were 0.18 ± 0.07, 0.15 ± 0.04, 0.06 ± 0.01, and 0.13 ± 0.04, respectively. An increase in γ with increasing RH was observed for all the dicarboxylic acids, suggesting a contribution by water amount in the particle, aqueous phase chemistry, and uptake of HO2–H2O. The anomalously low γ values for adipic acid are likely related to its high crystallization RH and thus provide a new clue that the water amount and/or RH have a significant influence on HO2 uptake. 相似文献
43.
Alora Akimoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):1339-1347
Abstract The effect of hexamethyi phosphoric acid triamide on the rate of polymerization of AlEt3-initiated polymerization of epichloro-hydrin and methyl methacryiate was examined. Benzene was used as solvent and the experiments covered AlEt3 /hexamethyi phosphoric acid triamide ratios from 1:0 to 1:2. Rate of polymerization increased to a maximum at AlEt3/ hexamethyi phosphoric acid triamide ratio of 1:0.2 and then decreased. The reaction of hexamethyi phosphoric acid triamide with AlEt, appears to modify the catalytic nature and copolymeriza-tion of epichlorohydrin with methyl methacryiate as demonstrated by enhanced methyl methacryiate reactivity in the presence of hexamethyi phosphoric acid triamide. 相似文献
44.
45.
Tomonori Yuasa Ryosuke Honma Hideki Funamizu Izumi Nishidate Yoshihisa Aizu 《Optical Review》2014,21(3):369-372
We are developing a daily health monitoring system that uses mobile phones with cameras and analyzes physiological conditions from R, G, and B intensity levels. However, since it is affected by various imaging conditions of the image input, color correction is required for accurate health monitoring. Therefore, we developed and validated a colorcorrection algorithm to derive reliable color information by correcting the spectral reflectance using the Wiener estimation and a color chart. 相似文献
46.
Tohru TakeiTakumi Ohki Yosuke HaradaNaoto Kumagai Hiroki FukumotoTake-aki Koizumi Akihiro MaedaTakahiro Kojima Yoshihisa SeiKohei Shiramizu Masahiro AbeMasashi Oota Takakazu Yamamoto 《Tetrahedron letters》2012,53(44):5907-5910
Dibromopyridines or dibromopyridone with -(CH2)m-SO3Na group(s) has been prepared via the reactions of the corresponding dibromopyridines with -OH and -NH2 groups with sultone. These compounds were converted into polymers with the -(CH2)m-SO3H groups via organometallic polycondensation. The polymer showed proton conducting properties and high stability toward oxidation. 相似文献
47.
Abstract Calorimetric titrations have been performed in anhydrous acetonitrile at 25°C to give the complex stability constants (K s) and the thermodynamic parameters (ΔGΔ, ΔHΔ and ΔSΔ) for the complexation of light lanthanoid(III) nitrates (La-Gd) with N-benzylaza-21-crown-7 3. Data analyses, assuming 1:1 stoichiometry, were successfully applied to all light lanthanoid-azacrown ether combinations employed. Using the present and previous data on 15- to 21- membered N-benzylazacrown ethers 1–3, the effect of ring size upon complexation behavior was discussed comparatively and globally from the thermodynamic point of view. The complexation behaviors are analyzed in terms of the size-fit concept, N-substituent coordination numbers, and lanthanoid's surface charge density. Thermodynamically the complexation of light lanthanoids with azacrown ethers is enthalpy-driven, while the cation selectivity is generally entropy-driven in acetonitrile. 相似文献
48.
Atsushi Tarui Shoji Kondo Kazuyuki Sato Masaaki Omote Hideki Minami Yoshihisa Miwa Akira Ando 《Tetrahedron》2013,69(5):1559-1565
A highly diastereoselective cross-coupling reaction of an α-bromo-α-fluoro-β-lactam with a wide range of aryl Grignard reagents was catalyzed by Ni/bis(oxazoline) in yields of up to 98%. The product was obtained diastereoselectively as an anti-isomer. This is the first successful α-arylation of an α-fluoro-β-lactam to produce diverse α-aryl-α-fluoro-β-lactams. 相似文献
49.
Akimoto H Xia JS Candela D Mullin WJ Adams ED Sullivan NS 《Physical review letters》2007,99(9):095301
The viscosity is measured for a Fermi liquid, a dilute 3He-4He mixture, under extremely high magnetic field/temperature conditions (Bor=1.5 mK). The spin-splitting energy microB is substantially greater than the Fermi energy kBTF; as a consequence the polarization tends to unity and s-wave quasiparticle scattering is suppressed for T相似文献
50.
We study the electrical transport properties of well-contacted ballistic single-walled carbon nanotubes in a three-terminal configuration at low temperatures. We observe signatures of strong electron-electron interactions: the conductance exhibits bias-voltage-dependent amplitudes of quantum interference oscillation, and both the current noise and Fano factor manifest bias-voltage-dependent power-law scalings. We analyze our data within the Tomonaga-Luttinger liquid model using the nonequilibrium Keldysh formalism and find qualitative and quantitative agreement between experiment and theory. 相似文献