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991.
A. V. Samodurov S. V. Vosel’ A. M. Baklanov A. A. Onishchuk V. V. Karasev 《Colloid Journal》2013,75(4):397-408
Homogeneous nucleation of ibuprofen vapor is studied in a nucleation flow chamber, a horizontal quartz tube equipped with an external heater. The area of the chamber where the nucleation proceeds most efficiently is determined, and the volume of this area is estimated. The temperature and supersaturation are determined and the homogeneous nucleation rate is calculated for this area. Saturation vapor pressure over liquid ibuprofen is measured in a temperature range of 353–383 K. Using an exact formula that has recently been derived for the nucleation rate based on the works by Kusaka, Reiss, as well as the Frenkel liquid-kinetics theory, surface tension and the radius of surface of tension of a critical nucleus σ= 25.9 mN/m and R s = 1.6 nm, respectively, are calculated at 318 K. The measurement of the surface tension of an ibuprofen planar surface shows that, at 318 K, σ∞ = 24.38 mN/m; i.e., σ is higher than σ∞ by 6%. A critical nucleus is established as containing nearly 36 ibuprofen molecules. 相似文献
992.
D. G. Filatova I. F. Seregina K. B. Osipov L. S. Foteeva V. V. Pukhov A. R. Timerbaev M. A. Bol’shov 《Journal of Analytical Chemistry》2013,68(2):106-111
A procedure for the determination of gallium in biological fluids by inductively coupled plasma mass spectrometry was developed. The detection limits of gallium calculated from the 3s value were 60 ng/L for urine, 32 ng/L for a model solution of intestinal juice, and 50 ng/L for serum. The accuracy of the procedure was tested using a standard addition method. The nature of a background signal on the masses of gallium isotopes was studied with the use of a high-resolution mass spectrometer, and the background concentration of gallium in biological fluids was evaluated (5–7 ng/L). It was found that a background level in measurements performed on a quadrupole mass spectrometer depends on the interfering influence of polyatomic ions with close m/z ratios rather than on the background concentration of gallium. The procedure makes it possible to study the stability of pharmaceutical preparations based on gallium in biological media, their metabolism, and the excretion of preparations from the body. 相似文献
993.
E. V. Tret’yakov V. G. Vasil’ev A. S. Bogomyakov G. V. Romanenko M. V. Fedin I. S. Antipin S. E. Solov’eva A. I. Konovalov R. Z. Sagdeev V. I. Ovcharenko 《Russian Chemical Bulletin》2013,62(2):543-547
A reaction of calix[4]arene tetraaldehyde with 2,3-bis(hydroxyamino)-2,3-dimethylbutane in DMF resulted in the corresponding 1,3-dihydroxyimidazolidine tetraadduct, whose oxidation gave a calix[4]arene (1,3-alternate) bearing four nitronyl nitroxyl-containing substituents at the upper rim. 相似文献
994.
A. A. Volod’kin L. N. Kurkovskaya G. E. Zaikov S. M. Lomakin 《Russian Chemical Bulletin》2013,62(10):2265-2265
995.
O. B. Belskaya N. N. Leont’eva T. I. Gulyaeva S. V. Cherepanova V. P. Talzi V. A. Drozdov V. A. Likholobov 《Russian Chemical Bulletin》2013,62(11):2349-2361
Influence of the nature of a doubly charged cation in the layered double hydroxides (LDH) on the conditions of formation and properties of mixed oxide phase MAlO x (M = Mg2+, Zn2+ and Ni2+), its ability to reconstruct the structure of the original precursor under contact with water has been studied. Hydrotalcite-like compounds and corresponding oxides with different M2+: M3+ ratio were investigated by XRD, TEM, TG-DTG-DTA, 27Al NMR, N2 adsorption, and differentiating dissolution. It has been found that the nature of the cation M2+ influences the conditions of LDH thermal decomposition, structural and textural characteristics of the formed mixed oxides. The obtained data can be used to synthesize the oxide supports with desired acid-base and adsorption properties. 相似文献
996.
1,1,2,2-Tetramethyl-3-trimethylsilyl-1,2-disilacyclobutane: synthesis and spontaneous polymerization
L. E. Gusel’nikov V. V. Volkova E. N. Buravtseva N. V. Ushakov V. G. Lakhtin L. A. Parshkova E. A. Chernyshev 《Russian Chemical Bulletin》2013,62(6):1462-1464
Gas-phase dehalogenation of 1,2-bis[chloro(dimethyl)silyl]-2-trimethylsilylethane with alkali metals gave 1,1,2,2-tetramethyl-3-trimethylsilyl-1,2-disilacyclobutane (3). Its spontaneous ring-opening polymerization at room temperature afforded an amorphous linear polymer with T g = ?8.9°C, M w = 3.47·105–3.85·105, and M w /M n = 2.43—2.86. According to spectroscopic data (IR and 1H, 13C, and 29Si NMR), the backbone of the polymer consists of alternating monomer units joined in the “head-to-tail” ([Me2SiCH(SiMe3)CH2SiMe2SiMe2CH-(SiMe3)CH2SiMe2]) and “head-to-head” ways ([Me2SiCH2CH(SiMe3)SiMe2SiMe2CH-(SiMe3)CH2SiMe2]). 相似文献
997.
R. M. Islamova O. I. Ishkinina S. V. Nazarova O. N. Chupakhin I. A. Utepova N. M. Andriyashina A. O. Terent’ev 《Russian Chemical Bulletin》2013,62(5):1282-1285
Cyclic peroxides as initiators for the radical polymerization of methyl methacrylate were proposed. The initial rates, initiation rates, and effective activation energies of polymerization initiated by cyclic peroxides and cyclic peroxide-1-pyridyl-2-ferrocene systems were determined. The radical yields to the volume upon the thermal decomposition of cyclic peroxides and their catalytic decomposition in the presence of 1-pyridyl-2-ferrocene were determined. In combination with 1-pyridyl-2-ferrocene cyclic peroxides form efficient initiating systems favoring an increase in the polymerization rate, a decrease in the molecular weights, and an increase in syndiotacticity of the synthesized poly(methyl methacrylate). 相似文献
998.
I. A. Khotina A. I. Kovalev N. S. Kushakova M. A. Babushkina Yu. V. Vasil’ev A. S. Peregudov 《Russian Chemical Bulletin》2013,62(10):2234-2244
A series of model cyclotrimers was studied by NMR spectroscopy using 2D COSY, HSQC, and HMBC correlations to establish the structures of branched oligophenylenes, whose branching center is the 1,3,5-triphenyl-substituted benzene ring. 相似文献
999.
E. V. Shchegol’kov Ya. V. Burgart V. I. Saloutin O. N. Chupakhin 《Russian Chemical Bulletin》2013,62(1):220-222
Fluorinated 2-amino-5-phenyl-1,3,4-thiadiazines were obtained for the first time. A study of their tautomeric structures revealed that trifluoromethyl-containing 1,3,4-thiadiazines exist as the 4H-tautomer in both solutions and the solid state, while their monofluoroaryl analogs exist as the 6H-tautomer. 相似文献
1000.
A. G. Medvedev A. A. Mikhailov P. V. Prikhodchenko T. A. Tripol’skaya O. Lev A. V. Churakov 《Russian Chemical Bulletin》2013,62(8):1871-1876
The crystal structures of new peroxosolvates of the following pyridinemonocarboxylic acids were studied: picolinic 2-C5H4NCOOH·H2O2 (1), nicotinic 3-C5H4NCOOH·H2O2 (2), and isonicotinic 4-C5H4NCOOH·2H2O2 (3). In these compounds, the acids exist exclusively as zwitterions, as opposed to non-solvated crystals. In compounds 1–3, the hydrogen peroxide molecules form two donor hydrogen bonds and, in some cases, one additional acceptor hydrogen bond. Peroxosolvate 2 can be considered as a novel drug formulation of vitamin B3. 相似文献