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71.
B. P. Sobolev A. M. Golubev L. P. Otroshchenko V. N. Molchanov R. M. Zakalyukin E. A. Ryzhova P. Herrero 《Crystallography Reports》2003,48(6):944-952
The structure of Ba0.75Lu0.25F2.25 crystals grown from melt has been studied by X-ray diffraction analysis (4729 measured reflections, 269 independent reflections with I > σ (I), R = 1.1%, R w = 0.7%). The crystals are crystallized in the cubic system, sp. gr. Pm $\bar 3$ m, with the lattice parameter a = 5.9870(9) Å. A new complex of defects is singled out—a supercluster of the composition {R 8[Ba6F71]}. This supercluster differs from the well-known rare earth octahedral supercluster of the composition {Ba8[R 6F68-69]} because its nucleus is formed not by RE cations but by an alkali earth cation, Ba. The {R 8[Ba6F71]} supercluster has a configuration close to that of the [B14F64] fragment of the fluorite structure and can replace the latter isomorphously. The model of the Ba0.75Lu0.25F2.25 crystals consisting of coherently intergrown isostructural microphases having different chemical compositions is characterized by the good agreement of the calculated and experimentally determined occupancies of the F1? positions. The comparison of the Ba0.8Yb0.2F2.2 (phase studied earlier) and Ba0.75Lu0.25F2.25 structures demonstrates the evolution of the defect structure along the series of rare earths with the corresponding change of the sp. gr. Fm $\bar 3$ m by the sp. gr. Pm $\bar 3$ m. 相似文献
72.
A. P. Dudka I. A. Verin V. N. Molchanov M. K. Blomberg O. A. Alekseeva N. I. Sorokina N. E. Novikova V. I. Simonov 《Crystallography Reports》2005,50(1):36-41
The structure of a K0.93Ti0.93Nb0.07OPO4 single crystal is studied at the temperature 30 K. The measurements are performed on a four-circle HUBER-5042 diffractometer with a DISPLEX DE-202 cryostat. Processing of the diffraction data and the preliminary refinement of the model are performed using the ASTRA program package. The final refinement of the structure model is made using the JANA2000 program complex. The refinement shows that the structure of a K0.93Ti0.93Nb0.07OPO4 crystal at T = 30 K is similar to its structure at room temperature. No phase transitions are revealed. Slight temperature-induced displacements of the potassium positions in the large cavities of the mixed framework are established. 相似文献
73.
Diev VV Stetsenko ON Tung TQ Kopf J Kostikov RR Molchanov AP 《The Journal of organic chemistry》2008,73(6):2396-2399
1,3-Dipolar cycloaddition of C-aryl,N-aryl (or N-methyl) nitrones with a number of 1,2-diphenylcyclopropenes substituted at the C(3) position occurs with the formation of expected "normal" cycloadducts (with N-methylnitrones) and products of their subsequent transformations. Among them are corresponding alpha-acetophenyl aziridines and tetra (or penta) -arylpyrroles. Aziridines and the normal cycloadducts can be also thermally converted to such arylpyrroles with moderate to good yields. Substitution at the C(3( position of cyclopropenes by an electron acceptor group decreases the reactivity of cyclopropenes. 相似文献
74.
S. P. Anikin V. F. Esipov V. Ya. Molchanov A. M. Tatarnikov K. B. Yushkov 《Optics and Spectroscopy》2016,121(1):115-122
An optical scheme of an acousto-optical imaging spectrometer for observing extended astrophysical objects with line emission spectra is proposed. The use of an additional prism with a specified angular dispersion makes it possible to separate images of an extended object at different emission lines and images generated by minor maxima of the acousto-optical filter transmission function. A prototype of the imaging spectrometer has been designed. 相似文献
75.
S.V. Golovkin A.P. Kozhevnikov V.P. Kubarovsky V.F. Kurshetsov L.G. Landsberg V.V. Molchanov V.A. Mukhin S.V. Petrenko V.A. Senko D.V. Vavilov V.A. Victorov V.Z. Kolganov G.S. Lomkatsi A.F. Nilov V.T. Smolyankin 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):409-416
New data for the diffractive reaction p+N→ [Σ0
K
+] +N at E
p= 70 GeV were obtained with partially upgraded SPHINX setup. The data are in a good agreement with the results of our previous
study of this reaction. In the mass spectrum M(Σ0
K
+) a structure at the threshold region with a mass ∼1810 MeV and a distinct X(2000) peak with M= 1989 ± 6 MeV and γ= 91 ± 20 MeV are observed. Unusual features of the massive X(2000) state (narrow decay width, anomalously
large branching ratio for the decay channel with strange particle emission) make it a serious candidate for cryptoexotic pentaquark
baryon with hidden strangeness |qqqsˉs>. We also present new results on the narrow threshold structure X(1810) with M= 1807 ± 7 MeV and γ= 62 ± 19 MeV which is produced in the region of very small P
2
T < 0.01 GeV2. The possibility of the Coulomb production mechanism for X(1810) is discussed.
Received: 28 April 1999 相似文献
76.
We study spectral properties of
the discrete Laplacian H on the half-space
with random boundary condition ;
the V(n) are independent random variables on a
probability
space and λ is the coupling constant.
It is known that if the
V(n) have densities, then on the interval
[-2(d+1), 2(d+1)] (=σ(H
0),
the spectrum of the
Dirichlet Laplacian) the spectrum of H is P-a.s.
absolutely continuous for all λ [JL1].
Here we show that if the random potential P
satisfies the
assumption of Aizenman–Molchanov [AM], then there
are constants λ
d
and
Λ
d
such that for
|λ|<lambda;
d
and |λ|>
Λ
d
the spectrum of
H outside σ(H
0)
is P-a.s. pure point with exponentially decaying
eigenfunctions.
Received: 3 December 1998 / Accepted: 27 May 1999 相似文献
77.
A. S. Demyanova T. L. Belyaeva A. N. Danilov Yu. A. Glukhov S. A. Goncharov S. V. Khlebnikov V. A. Maslov Yu. D. Molchanov Yu. E. Penionzkevich R. V. Revenko M. V. Safonenko Yu. G. Sobolev W. Trzaska G. P. Tyurin A. A. Ogloblin 《Physics of Atomic Nuclei》2009,72(10):1611-1616
We present new measurements of the α + 12C elastic and inelastic (to the states 4.44, 7.65, and 9.64 MeV) scattering at E lab = 110 MeV in the wide angular range from ~10° to 175°, which enable us to examine the condensate and cluster properties of the low-lying excited states in 12C. We present the diffraction-radius analysis of our data together with a considerable amount of the existing data. The magnitudes of the diffraction radii for the ground and the first excited (4.44 MeV) states are found to be equal, whereas they appear to be enhanced by ~0.6 fm both for 7.65 and 9.64 MeV states. This result shows that the radius of the Hoyle’s 0 2 + , 7.65 MeV state in 12C is by a factor of ~1.2–1.3 larger than that of the ground state. It is demonstrated that the direct transfer mechanism of 8Be dominates at the largest angles in all four reactions reported here. The configuration corresponding to the transfer of 8Be in its ground state (I π = 0+) with L = 0 turns out to be the most important for the 7.65 MeV state of 12C. Evidence of existence of some features of α-condensed structure of the Hoyle’s 0 2 + state in 12C was obtained: its enhanced radius and large contribution of α-particle configuration with L = 0. 相似文献
78.
The rheological properties of semidilute aqueous solutions containing long cylindrical micelles of an anionic surfactant, potassium oleate, are studied. It is shown that, at surfactant concentrations above 1 wt %, the rheological properties of the solutions are adequately described in terms of the simple Maxwell model of a viscoelastic liquid characterized by a single relaxation time. Based on the analysis of normalized dependences of the loss modulus on the storage modulus, the characteristic times of the processes governing the rheological properties of the above systems, i.e., the average breaking time and reptation time of micelles, are estimated. It is found that the breaking time of micelles decreases and relaxation time increases with increasing surfactant concentration due to lengthening of micellar chains. 相似文献
79.
Mariia M. Efremova Alexander P. Molchanov Anna G. Larina Galina L. Starova Rafael R. Kostikov Alexander V. Stepakov 《Helvetica chimica acta》2016,99(7):487-493
Treatment of several Diels–Alder adducts of cyclopropenecarboxylates and 1,3‐diarylisobenzofurans with a strong acid triggers a skeletal rearrangement resulting in 4,8b‐dihydro‐3aH‐indeno[1,2‐b]furans. 相似文献
80.
2-Bromo-2-fluoro-1-alkylidenecyclopropanes heated in polar solvents undergo isomerization into substituted 3-bromo-2-fluoro-1,3-butadienes. 2-Bromo-3-methyl-1-methylene-3-phenyl-2-fluorocyclopropane at heating afforded a mixture of substituted 1-(bromofluoromethylene)cyclopropane and isomeric 1-bromo-1-fluoro-1,3-butadienes. 相似文献