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991.
Two formulas were developed for use in computing 1-tailed upper limits for future HorRat values obtained from the collaborative study of materials. One formula is applicable when a future sample HorRat value H [formula: see text] is computed based on a known concentration (e.g., C = spike level and RSD(R) is the sample relative reproducibility standard deviation) and the other formula is applicable when the true concentration (C) is unknown and a future sample HorRat value [formula: see text] is computed using the sample mean (e.g., y, the collaborative study overall mean for an analyte). A Monte Carlo simulation procedure was developed using the Statistical Analysis System (SAS) software to assess the accuracy of the 2 developed formulas. Based on the degree of closeness between the simulated and calculated limits, the formulas for computing upper limits for future sample HorRat values will prove to be useful to Study Directors in determining worst case scenarios concerning a method's reproducibility precision relative to that predicted using the "Horwitz equation". We also define the current empirical HorRat limits as 1-tailed 100p% upper limits to assess the statistical consequence, in a probability sense, of their application as an analytical methods screening tool. 相似文献
992.
Taegweon Lee Il Jung Soo-Hyoung Lee Jaejung Ko 《Journal of organometallic chemistry》2006,691(9):1887-1896
A novel series of blue emitting silylene-spaced diphenylanthracene derivatives have been synthesized and characterized. The rhodium-catalyzed hydrosilylation of bis[4-(dimethylsilyl)phenyl]anthracene 3-4 yielded stable 9,10-disubstituted (E)-divinylsilylene-diphenylanthracene products 7-10 and salt elimination reaction of bis[4-(chlorodimethylsilyl)phenyl]anthracene 5-6 gave 9,10-disubstituted disilyldiphenylanthracene compounds 11-14. They are fluorescent in the blue region with good quantum efficiencies. The rhodium-catalyzed polyaddition including 2-tert-butyl-9,10-bis[4-(dimethylsilyl)phenyl]anthracene (4) afforded the nonconjugated copolymer 15. 相似文献
993.
The new dinuclear half-sandwich complexes of titanium with xylene bridge, [Ti(η5-cyclopentadienyl)Cl2L]2[CH2-C6H4-CH2] (L = Cl (3), L = O-2,6-iPr2C6H3 (4), L = N(SiMe3)(2,6-Me2C6H3) (5)), have been synthesized. The complexes 4 and 5 have been prepared by the reaction of the complex 3 with the corresponding lithium salts of aryloxy and anilide. Structure of these complexes has been characterized by 1H and 13C NMR. The change of substituent from chloride, 3, to anilide, 5, at titanium resulted in chemical shift change of cyclopentadienyl protons from 6.92 and 6.79 to 6.13 and 5.95 ppm probably due to the positive electron density delivery from the anilide group. It was found that all three half-titanocenes were effective catalyst for the generation of SPS (syndiotactic polystyrene). Xylene bridged dinuclear catalyst (4) with aryloxy substituent exhibited very high activity (458 kg of SPS/(mol of [Ti])h), at 40 °C, whereas the analogous hexamethylene bridged dinuclear half-titanocene catalyst (7) showed a lower activity (80.7 kg of SPS/(mol of [Ti])h) under the same conditions. While the catalyst 3 was the most active catalyst among three complexes less than 40 °C the catalyst 5 exhibited the highest activity at 70 °C. Xylene linkage was suggested to be too stiff to permit any kind of intramolecular interaction between two active centers. Lack of steric disturbance due to the rigidity of the xylene bridge might give rise to the similar properties of dinuclear metallocene to the corresponding mononuclear metallocene to result in not only the facile coordination of monomer at the active center to lead high activity but also the easier β-H elimination comparing to the dinuclear catalysts with the flexible bridge to result in the formation of lower molecular weight polymer. 相似文献
994.
Jum Suk Jang Sang Min Ji Jong Hyeon Jung Jae Sung Lee 《Journal of solid state chemistry》2006,179(4):1067-1075
Amorphous precursors to nitrogen-doped TiO2 (NTP) and pure TiO2 (ATP) powders were synthesized by hydrolytic synthesis and sol-gel method (SGM), respectively. Corresponding crystalline phases were obtained by thermally induced transformation of these amorphous powders. From FT-IR and XPS data, it was concluded that a complex containing titanium and ammonia was formed in the precipitate stage while calcination drove weakly adsorbed ammonium species off the surface, decomposed ammonia bound on surface of precipitated powder and led to substitution of nitrogen atom into the lattice of TiO2 during the crystallization. The activation energies required for grain growth in amorphous TiO2−xNx and TiO2 samples were determined to be 1.6 and 1.7 kJ/mol, respectively. Those required for the phase transformation from amorphous to crystalline TiO2−xNx and TiO2 were determined to be 129 and 142 kJ/mol, respectively. A relatively low temperature was required for the phase transformation in NTP sample than in ATP sample. The fabricated N-doped TiO2 photocatalyst absorbed the visible light showing two absorption edges; one in UV range due to titanium oxide as the main edge and the other due to nitrogen doping as a small shoulder. TiO2−xNx photocatalyst demonstrated its photoactivity for photocurrent generation and decomposition of 2-propanol (IPA) under visible light irradiation (). 相似文献
995.
Jae-Chul Jung 《Tetrahedron letters》2006,47(45):7969-7972
A simple and efficient synthesis of cyclic urethanes and related oxazinanones 1a-l from diazoketones 3a-l is described. The transformation involves generation of carbenes by activation of diazo groups using metal triflates in intramolecular diazocarbonyl insertion reactions in high overall yields. 相似文献
996.
Walter Jung 《无机化学与普通化学杂志》2006,632(15):2461-2466
Mg3Ir3Si8, a New Magnesium Iridium Silicide with Si4 Tetrahedra and Si12 Truncated Tetrahedra The ternary silicide Mg3Ir3Si8 (cubic, a = 1221.4(1) pm, space group , 8 formula units per unit cell) was prepared by reaction of the elemental components in a sealed molybdenum container (1000 °C, 1 d, cooled with 100 °/h). The crystal structure was determined from single crystal data. Short distances in the three‐dimensional iridium silicon network indicate strong Ir‐Si‐bonding (d(Ir‐Si) = 240.5(2) and 245.6(1) pm). In addition, homonuclear bonding seems to be important, resulting in the formation of Si4‐tetrahedra (d(Si‐Si) = 257(1) pm), and Mg centered Si12‐polyhedra with the shape of truncated tetrahedra (d(Si‐Si) = 241(1) and 261.0(9) pm). Furthermore, Mg4‐tetrahedra with Mg‐Mg‐distances of 355(2) pm are formed. The structure may be derived from the structure of the isotypic compounds Mg5Pd10Si16 and Mg5Pt10Si16 by adding a Mg siteset and subtracting a platinum metal siteset. It can be described by an expanded cubic “close” packing of MgIr6‐octahedra in which Si4‐tetrahedra reside in the octahedral holes while Mg4‐tetrahedra and MgSi12‐units occupy one half of the tetrahedral holes each. 相似文献
997.
Sang‐Hoon Ji Wan Pyo Hong Seung Ho Ko Kee‐Jung Lee 《Journal of heterocyclic chemistry》2006,43(3):799-801
A new synthesis of 4‐carbomethoxynaphtho[2,1‐c]isoxazoles 4a‐d from methyl 3‐(alkynylphenyl)‐2‐nitromethyl‐2‐propenoates 2a‐d by the intramolecular nitrile oxide cycloaddition is described. The latter are readily obtained from 2‐alkynylbenzaldehydes through the Baylis‐Hillman adduct acetates 1a‐d followed by nucleophilic substitution of nitrite anion. 相似文献
998.
For the first time, a simple and facile approach for the synthesis of diblock codendrimers by fusion between the azide focal point functionalized Fréchet-type polyether and the propargyl focal point functionalized Tomalia-type PAMAM dendrons has been described based on click chemistry, i.e., the copper-catalyzed cycloaddition reaction between alkyne and azide. 相似文献
999.
Fourier-domain low-coherence interferometry for differential mode delay analysis of an optical fiber
We propose a novel mode analysis and differential mode delay measurement method for an optical fiber using Fourier-domain low-coherence interferometry. A spectral interferometer based on a Mach-Zehnder interferometer setup was used with a broadband source and an optical spectrum analyzer to detect relative temporal delays between the guided modes of a few-mode optical fiber by analyzing spectral interference signals. We have shown that experimental results of the proposed method agree well with those results obtained by using a conventional time-domain measurement method. We have demonstrated that this new mode analysis technique has high sensitivity (<60 dB) and very good resolution (<1 ps/m). 相似文献
1000.
Dumbbell‐shaped amphiphiles based on an elongated rod segment can self‐assemble into planar networks with in‐plane hexagonally ordered pores in aqueous solution. On increasing temperature, the 2D networks change into hollow capsules passing through the closed sheets as an intermediate structure due to a LCST behavior of the oligoether dendritic exterior. The primary driving force for this interesting feature seems to originate from a consequence of the energy balance between hydrophobic interactions of anisotropic rod segments and alkyl chains, and repulsive interactions between dissimilar blocks. This dynamic structural variation triggered by external stimuli in a self‐assembling system can provide a useful strategy to create smart supramolecular materials and biomimetic systems.