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81.
S. M. Sergazina B. K. Kasenov E. S. Mustafin Zh. I. Sagintaeva S. Zh. Davrenbekov M. A. Akubaeva Sh. B. Kasenova R. Sh. Erkasov E. K. Zhumadilov 《Russian Journal of Inorganic Chemistry》2010,55(10):1607-1610
Ferrites of composition ErMIFe2O5 (MI = Li, Na, K, Cs) were synthesized by a solid-phase method. The structure of the ferrites was for the first time studied by X-ray powder diffraction. Crystal systems, unit cell parameters, and X-ray and pycnometric densities were determined. For ErLiFe2O5, a = 10.510 Å, c = 14.270 Å, V°= 1616.16 Å3, Z = 16, V subcell ° = 101.01 Å3, ρx = 6.01 g/cm3, ρpyc = 5.97 ± 0.04 g/cm3; for ErNaFe2O5, a = 10.519 Å, c = 15.510 Å, V° = 1759.56 Å3, Z = 16, V subcell ° = 109.90 Å3, ρx = 5.77 g/cm3, ρpyc = 5.72 ± 0.08 g/cm3; for ErKFe2O5, a = 11.050 Å, c = 15.480 Å, V° = 1937.33 Å3, Z = 16, V subcell ° = 121.08 Å3, ρx = 5.46 g/cm3, ρpyc = 5.41 ± 0.04 g/cm3; and for ErCsFe2O5, a = 10.78 Å, c = 16.01 Å, V° = 1905.37 Å3, Z = 16, V subcell ° = 119.09 Å3, ρx = 6.86 g/cm3, ρpyc = 6.61 ± 0.01 g/cm3. 相似文献
82.
R. G. Bulgakov S. P. Kuleshov Z. S. Valiullina B. A. Mustafin 《Russian Chemical Bulletin》1999,48(6):1091-1094
Chemiluminescence (CL) of triphenylmethyl organometallics (TPM), Ph3CNa, Ph3CMgCl, and Ph3CLnCl2 (Ln=Cd, Eu, and Dy), in THF and toluene during oxidation by O2 and the (NH4)2Ce(NO3)6 complex was found. The first CL is caused by the luminescence of two emitters: (Ph3C)*, emitting in the green spectral region (λmax=524, 550 nm), and an unstable product of substitution of the hydrogen atom in the phenyl ring of the Ph3C radical, emitting in the red region (λmax=580±20 nm). The emitter of the second CL, Ph3C.*, is generated in the elementary electron transfer from the Ph3C− anion to CeIV, reducing the latter to CeIII.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1102–1105, June, 1999. 相似文献
83.
Konenkov NV Korolkov AN Machmudov M 《Journal of the American Society for Mass Spectrometry》2005,16(3):379-387
Modulation of the voltages applied to a quadrupole mass filter (QMF), either RF or RF and DC, leads to splitting of the stability region into islands of stability. The ion optical properties, such as transmission, resolving power and peak tails of the first upper stability islands have been investigated by numerical simulation of ion trajectories. The dependence of the location of this island on the amplitude of the modulation and the parameter nu = omega/Omega = Q/P where omega is modulation frequency, Omega is main angular radio frequency, and Q and P are integers, is calculated in detail. Different methods of adjusting the QMF resolution are examined. It is found that operation at the upper and lower tips of the stability islands created by amplitude modulation of the RF voltage is preferred, because of the technical simplicity of this method and a reduction of the required separation time. Amplitude modulation improves the performance of a QMF constructed with round rods, in comparison to perfect quadrupole fields. For example, with amplitude modulation of the RF, to reach a resolution of R(0.1) = 1200 requires only about 75 RF cycles of ion motion in a quadrupole field created by round rods. 相似文献
84.
Gallyamov MO Tartsch B Khokhlov AR Sheiko SS Börner HG Matyjaszewski K Möller M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(18):4599-4605
Environment-controlled scanning force microscopy allowed us to study adsorption and desorption of single poly(methacrylate)-graft-poly(n-butyl acrylate) brush molecules on mica in real time. The molecules transform reversibly from a two-dimensional, extended wormlike state to a compact globular state. The dynamics of the conformational transition was sufficiently slow in order to allow its observation by scanning force microscope in real time. The reversible transformation is effected by coadsorption of water or ethanol, the latter introduces the collapse. Adsorbing ethanol and water from the vapour atmosphere results in a change of the surface properties of mica, either favouring adsorption or desorption of the graft polymer. When the extended, tightly adsorbed poly(n-butyl acrylate) brush molecules are exposed to ethanol vapour, the macromolecules swell and contract to form compact globules. Exchanging the ethanol vapour to a humid atmosphere caused the molecules to extend again to a wormlike two-dimensional conformation. Coexistence of collapsed and extended strands within the same molecule indicates a single-molecule first-order transition in agreement with observations on Langmuir films previously reported. 相似文献
85.
A. G. Mustafin I. N. Khalilov I. B. Abdakhmanov G. A. Tolstikov 《Chemistry of Natural Compounds》1989,25(6):693-695
A convenient route is described for the preparation of 1,4-dimethylcarbazole — the key compound in the synthesis of the antitumoral alkaloid ellipticine. The interaction of 2,5-xylidine with 3-chlorocyclohexene led to N-(cyclohex-2-enyl)-2,5-xylidine (I), the two-hour heating of which at 140–150°C gave the product of an amino-Claisen rearrangement, 6-(cyclohex-2-enyl)-2,5-xylidine (II) with a yield of 82%. The intramolecular cyclization of compound (II) in polyphosphoric acid (130–140°C, 5 h) led to 5,6,7,8,12,13-hexahydro-1,4-dimethylcarbazole (III) in a yield of 75%. The dehydrogenation of substance (III) by boiling in trimethylbenzene in the presence of Pd/C gave 1,4-dimethylcarbazole (IV) with a yield of 87%. The conditions for performing the reactions and the physicochemical constants of the compounds obtained are given. 相似文献
86.
The novel mixed-valence alkoxide [Eu3+(4)Eu2+O(OPri)12(HOPri)]HOPri (1) has been prepared and structurally and spectroscopically characterized. The three synthesis routes (i) metathesis of 4EuCl3, EuI2, and 14KOPri combined with hydrolysis with 1H2O, (ii) oxidation of 5[Eu4(OPri)10(HOPri)3]2HOPri with 1.5O2, and (iii) reduction of Eu5O(OPri)13 with 0.8[Eu4(OPri)10(HOPri)3]2HOPri all yielded pure 1, whereas (iv) reduction of Eu5O(OPri)13 with 0.36-0.5 mol of europium metal produced impure 1. The compound, having the average Eu oxidation number +2.8, is very sensitive toward further oxidation to Eu5O(OPri)13 and is part of a redox series of europium 2-propoxides with average oxidation states +2.5, +2.8, and +3. The square pyramidal molecular structure, containing an oxo-oxygen atom in the basal plane, is similar to that of the well-known Ln5O(OPri)13; the main difference is the substitution of an Eu3+(-)OPri pair for an Eu2+(-)HOPri pair in the basal plane. Fourier transform infrared (FT-IR) and UV-visible spectroscopy showed that the solid-state structure was retained on dissolution in hexane and toluene-HOPri. The compound was further characterized by differential scanning calorimetry and solubility studies. 相似文献
87.
Gunnar Westin Marat Moustiakimov Mikael Kritikos 《Journal of Sol-Gel Science and Technology》2003,26(1-3):115-118
A new chloro-oxo-alkoxide, Sr2Er2OCl(OPr
i
)7(HOPr
i
)4 has been prepared by reacting 4ErCl3 with 5Sr dissolved in toluene:HOPr
i
. The structure, determined by single-crystal X-ray techniques, is built from two polymer strands, each formed by repeating two molecular Sr2Er2O(OPr
i
)7(HOPr
i
)4 complexes, inter-tied by a chloro atom. The four independent, but very similar complexes contain two Er and two Sr ions, all binding to a central oxo ion. The great similarity of the FT-IR and UV-vis-NIR spectra of the solid and the hexane/toluene/2-propanol solutions shows that the molecular complexes have similar complex structures in the solid state and in solution. 相似文献
88.
Bogatyryova GV Fel'de CV Polyanskii PV Ponomarenko SA Soskin MS Wolf E 《Optics letters》2003,28(11):878-880
We propose and experimentally implement a method for the generation of a wide class of partially spatially coherent vortex beams whose cross-spectral density has a separable functional form in polar coordinates. We study phase singularities of the spectral degree of coherence of the new beams. 相似文献
89.
90.
A new reagent, 2,2-dicarboxydiphenylamine, vanadox, is proposed for the photometric determination of vanadium in steels, high temperature alloys and ferrotitanium ores. In strongly acidic medium the reagent is selective for vanadium(V) and only eerium(IV) interferes. 相似文献