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991.
Z.Q. Li D.X. Zhang X.H. Zhang Y.Q. Gao X.J. Liu E.Y. Jiang 《Physics letters. A》2007,370(5-6):512-516
The charge ordering characteristics in Y0.5Ca0.5MnO3 manganite, prepared by sol–gel process, have been investigated experimentally. It is found that the superlattice diffractions appear in the electron diffraction patterns recorded at low temperatures, while only basic Brag diffraction spots can be observed when temperature is higher than 300 K. This provides direct evidence for the existence of charge ordering in Y0.5Ca0.5MnO3. The magnetization and specific heat measurements indicate the charge ordering temperature of Y0.5Ca0.5MnO3 is 290 K, around which both the magnetization and specific heat reveal anomalous behaviors. We also observed that the MnO bond length changed remarkably and the effective number of carriers reduced prominently with decreasing temperature around charge ordering temperature through transform infrared spectra measurements. 相似文献
992.
Z. Barticevic M. Pacheco C. A. Duque L. E. Oliveira 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(4):303-309
A theoretical study, within the effective-mass approximation, of the
effects of applied magnetic fields on excitons in disk-shaped
GaAs-Ga1-xAlxAs quantum dots is presented. Magnetic fields
are applied in the growth direction of the semiconductor
heterostructure. The parity of the excitonic envelope function
related to the simultaneous exchange of ze→-ze and
zh→-zh is a good quantum number and the wave
function, both the odd and even parity, can be expanded as
combination of products of the quantum well electron and hole
function that preserves the parity with appropriate Gaussian
functions. We have simultaneously obtained the energies of the
excitonic ground and excited states and discuss the behavior of
these energies as a function of the magnetic field. 相似文献
993.
Toshiki Yasokawa Ichirou Ishimaru Masahiro Kondo Shigeki Kuriyama Tsutomu Masaki Kaoru Takegawa Naotaka Tanaka 《Optical Review》2007,14(4):161-164
This paper describes a method for measuring the three-dimensional (3D) refractive-index distribution in a single cell. The
method can be used to observe the distribution of cell components without fluorescence staining. The two-dimensional optical
path length distributions from multiple directions are obtained by non-contact rotation of the cell. These optical path lengths
are converted into the line integrals of the refractive index, and the 3D refractive-index distribution is reconstructed by
means of computed tomography. The refractive-index distribution in a breast cancer cell can be measured using a phase-shifting
Mach—Zehnder interferometer in conjunction with proximal two-beam optical tweezers. 相似文献
994.
K. Jin Z. C. Wang Q. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):325-332
We study the absorption spectra of a degenerate V-type
atom, where a resonant driving field and a probe field drive
different branches of transitions and a dc field is applied to
drive the transition between two excited states. The effects of
vacuum induced coherence (VIC) on the absorption spectra are
investigated. It is demonstrated that in some special cases the
VIC can lead to the depression of absorption and narrow resonance.
The origin of these features are discussed. When the pump field
and the dc field have the same intensity, it is interesting to
find that the whole absorption spectrum comes mainly from the
absorptions induced by the interferences among different
transitions between dressed states. 相似文献
995.
V. S. Pavlovich 《Journal of Applied Spectroscopy》2007,74(2):180-187
The effect of dispersion interactions on the electronic spectra of organic compounds is analyzed within second-order perturbation
theory. A formula is obtained which makes is possible to determine the change in the polarizability of the molecules upon
excitation, Δαeg, using data on the effect of the bulk polarizability Pn of the solvent on the position of the electronic spectrum. It is shown that when the solutions are cooled, the long-wavelength
shift of the absorption spectra for the studied anthracenes in alcohols is mainly due to dispersion interactions and is caused
by an increase in Pn. The possibility of using the new formula for Δαeg is demonstrated for anthracenes as an example. It is found that for anthracene, 1-chloroanthracene, 9,10-dichloroanthracene,
9,10-dibromoanthracene, 9,10-diiodoanthracene Δαeg is 16.5, 16.9, 17.2, 18.6, and 20.2 Å3 respectively.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 162–168, March–April, 2007. 相似文献
996.
X. M. Chen J. X. Shao Z. H. Yang H. Q. Zhang Y. Cui X. Xu G. Q. Xiao Y. T. Zhao X. A. Zhang Y. P. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):281-286
Al K-shell X-ray yields are measured with highly charged Arq+ ions
(q=12–16) bombarding against aluminium. The energy range of the Ar
ions is from 180 to 380 keV. K-shell ionization cross sections of aluminium are also obtained from the yields data.
The experimental data is explained within the framework of 2pπ
-2pσ rotational coupling. When Ar ions with 2p-shell vacancies are
incident on aluminium, the vacancies begin to reduce. Meanwhile, collisions
against Al atoms lead to the production of new 2p-shell vacancies of Ar
ions. These Ar 2p-shell vacancies will transfer to the 1s orbit of an Al
atom via 2pπ-2pσ rotational coupling leading to the emission of
a K-shell X-ray of aluminiun. A model is constructed based on the base of
the above physical scenario. The calculation results of the model are in
agreement with the experimental results. 相似文献
997.
N. Stevanović D. Nikezić 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):397-406
Collision of swift ions with atoms was considered in this paper. The
projectile and target atoms were modeled as assemblies of quantum
oscillators and it was assumed that both, target and projectile could be
excited or ionized, without charge exchange. The model presented here is an
extension of the one given by Sigmund and Haagerup [Phys. Rev. A 34, 892 (1986)]. The number of electrons bound to the projectile, as a function of the projectile velocity,
was used from Cabrera-Trujillo et al. [Phys. Rev. A 55, 2864 (1997)]. Contributions to energy loss from excitation of the projectile and targets were separately considered. It
has been found that projectile excitation contributes up to 20% to the
total energy loss in the lower energy region. Comparisons with other
authors, including SRIM 2003, are also given and good agreement was found. 相似文献
998.
Rajesh Das 《Applied Surface Science》2007,253(14):6068-6073
Sn doped In2O3 films are deposited by rf-magnetron sputtering at 300 °C under Ar, Ar + O2 and Ar + H2 gas ambients. For the film prepared under argon ambient, electrical resistivity 6.5 × 10−4 Ω cm and 95% optical transmission in the visible region have been achieved optimizing the power and chamber pressure during the film deposition. X-ray diffraction spectra of the ITO film reveal (2 2 2) and (4 0 0) crystallographic planes of In2O3. With the introduction of 1.33% oxygen in argon, (2 2 2) peak of In2O3 decreases and resistivity increases for the deposited film. With further increase of oxygen in the sputtering gas mixture crystallinity in the film deteriorates and both the peaks disappeared. On the other hand, when 1.33% hydrogen is mixed with argon, the resistivity of the deposited film decreases to 5.5 × 10−4 Ω cm and the crystallinity remains almost unchanged. In case of reactive sputtering, the deposition rate is lower compared to that in case of non-reactive sputtering. HRTEM and first Fourier patterns show the highly crystalline structure of the samples deposited under Ar and Ar + H2 ambients. Crystallinity of the film becomes lower with the introduction of oxygen in argon but refractive index increases from 1.86 to 1.9. The surface morphology of the ITO films have been studied by high resolution scanning electron microscopy. 相似文献
999.
F. Pippig 《Applied Surface Science》2007,253(16):6817-6823
Some surface bonded and fluram labeled primary amines show a new red-shifted emission in their fluorescence spectrum. We compared the fluorescence of fluram bonded to various amine functionalized surfaces including tetraethylene pentamine (TEPA), 1,2-ethylene diamine (EDA), 3-aminopropyltriethoxy silane (APTES) and trimetylol-propanetris-(beta-aziridino)-propionate (ATA). All reactions were also monitored using XPS. It was found that the new spectral features seem to be related to the local density of amino groups on the surface. In order to verify this hypothesis we synthesized a surface bonded dendrimer with a step-wise increasing NH2 density. Using molecules with different lengths as branches in the dendrimer, the amine density can be varied. Only in the case of the highest density, the new fluorescence emission was detected. Consequently, the fluorescence of fluram coupled to amines at a surface can be used to quantify the concentration of these amines and the appearance of the red-shifted emission indicates a high local density of the amino groups. 相似文献
1000.
Present work explored a room temperature, simple and low cost chemical route for the preparation of hydrophilic cobalt oxide films from alkaline cobalt chloride (CoCl2:6H2O) and double distilled water precursor solutions. As-deposited cobalt oxide films showed amorphous nature, which is one of the prime requirements for supercapacitor, as confirmed from X-ray diffraction studies. Changes in direct band gap energy and electrical resistivity of as-deposited cobalt oxide films were confirmed after annealing. Spherical grains of about 40-50 nm diameters were uniformly distributed over the substrate surface. Surface wettability studied in contact with liquid interface, showed hydrophilic nature as water contact angle was <90°. Finally, presence of cobalt-oxygen covalent bond was observed from Raman shift experiment. 相似文献