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141.
Tatiana Moskalets Alexei Nurmagambetov 《The European Physical Journal C - Particles and Fields》2015,75(11):551
We establish solutions corresponding to AdS\(_4\) static charged black holes with inhomogeneous two-dimensional horizon surfaces of constant curvature. Depending on the choice of the 2D constant curvature space, the metric potential of the internal geometry of the horizon satisfies the elliptic wave/elliptic Liouville equations. We calculate the charge diffusion and transport coefficients in the hydrodynamic limit of gauge/gravity duality and observe the exponential suppression in the diffusion coefficient and in the shear viscosity-per-entropy density ratio in the presence of an inhomogeneity on black hole horizons with planar, spherical, and hyperbolic geometry. We discuss the subtleties of the approach developed for a planar black hole with inhomogeneity distribution on the horizon surface in more detail and find, among others, a trial distribution function, which generates values of the shear viscosity-per-entropy density ratio falling within the experimentally relevant range. The solutions obtained are also extended to higher-dimensional AdS space. We observe two different DC conductivities in 4D and higher-dimensional effective strongly coupled dual media and formulate conditions under which the appropriate ratio of different conductivities is qualitatively the same as that observed in an anisotropic strongly coupled fluid. We briefly discuss ways of how the Liouville field could appear in condensed matter physics and outline prospects of further employing the gauge/gravity duality in CMP problems. 相似文献
142.
Baishali Chakraborty Kumar S. Gupta Siddhartha Sen 《The European Physical Journal B - Condensed Matter and Complex Systems》2015,88(6):155
We analyze the screening of an external Coulomb charge in gapless graphene cone, which is taken as a prototype of a topological defect. In the subcritical regime, the induced charge is calculated using both the Green’s function and the Friedel sum rule. The dependence of the polarization charge on the Coulomb strength obtained from the Green’s function clearly shows the effect of the conical defect and indicates that the critical charge itself depends on the sample topology. Similar analysis using the Friedel sum rule indicates that the two results agree for low values of the Coulomb charge but differ for the higher strengths, especially in the presence of the conical defect. For a given subcritical charge, the transport cross-section has a higher value in the presence of the conical defect. In the supercritical regime we show that the coefficient of the power law tail of polarization charge density can be expressed as a summation of functions which vary log periodically with the distance from the Coulomb impurity. The period of variation depends on the conical defect. In the presence of the conical defect, the Fano resonances begin to appear in the transport cross-section for a lower value of the Coulomb charge. For both sub and supercritical regime we derive the dependence of LDOS on the conical defect. The effects of generalized boundary condition on the physical observables are also discussed. 相似文献
143.
周富军 《高校应用数学学报(英文版)》2006,21(2):143-151
§1Introduction Avarietyofpartialdifferentialequationmodelsfortumorgrowthortherapyhave beendevelopedinthelastthreedecades[see2,3,16-18,21-26].Mostofthosemodelsare informoffreeboundaryproblems,andareverydiversified.Rigorousmathematical analysisofsuchfreeboundaryproblemshasdrawngreatinterest,andmanyinteresting resultshavebeenestablished[4-15].Inthispaperwedealwithamathematicalmodeldescribingtumorchemotherapy.In thismodelthetumorisviewedasdenselypacked,radially-symmetricsphereofradiusR(t)contain… 相似文献
144.
Seddique M. Ahmed 《Journal of solution chemistry》2008,37(7):919-932
The chromaticity of poly(o-anisidine) (POAN) doped with different acids (HA), HA-doped POAN, has been studied by the spectrophotometric technique and
the results were substantiated by molecular mechanics (MM+) calculations. The observed absorbance decrease (λ around 720 nm, dark green coloration) with increasing concentration of the inorganic oxidizing agent (KMnO4) can be attributed to the oxidative hydrolysis mechanism. The oxidative hydrolysis constant (K
h) is highly dependent on the strength of the acid used. The HClO4-doped POAN matrix has the ability to store about 128.878 kJ⋅g−1 chromogenic energy (CE) at the wavelength 720 nm in a condensed lightweight form. MM+ calculations suggest that the potential
energy (PE) in kJ⋅mol−1 of the optimum molecular geometric (OMG) structure of the HClO4-doped POAN matrix is at least two (2.052) times more stable than the OMG of the base form (POAN-EB) of the POAN matrix. Kinetic
parameters of the oxidative hydrolysis reaction of the HA-doped POAN matrix were deduced from absorbance variations with time.
The results of computer-oriented kinetic analysis indicate that the rate-controlling step for HA-doped POAN oxidative hydrolysis
is governed by the Ginstling-Bronshein equation that represents three-dimensional diffusion (D4). Activation parameters for
the oxidative hydrolysis of the HClO4-doped POAN matrix were computed and discussed. 相似文献
145.
146.
147.
Anguo Ying Ming Zheng Haidan Xu Fangli Qiu Changhua Ge 《Research on Chemical Intermediates》2011,37(8):883-890
An efficient and facile protocol for aza-Michael addition of aliphatic and aromatic amines to electron-deficit alkenes using
[TMG][Lac] as catalyst under solvent-free conditions was established. 相似文献
148.
149.
Two samples of mussels (Mytilus edulis) were collected from the southwest of Ireland. One sample contained domoic acid, the other sample contained okadaic acid,
dinophysistoxin-2 and azaspiracid-1, -2 and -3. Wet and freeze-dried reference materials were prepared from each of the two
samples to test for differences in homogeneity, stability and extractability of the analytes in either condition. Wet materials
were homogenised, aliquoted and hermetically sealed under argon and subsequently frozen at −80 °C. Dry materials were similarly
homogenised but frozen in flat cakes prior to freeze-drying. After grinding, sieving and further homogenisation, the resulting
powder was aliquoted and hermetically sealed. Domoic acid materials were characterised using HPLC–UV, while LC–MS was used
for the determination of lipophilic toxins. The extractabilities of all phycotoxins studied were comparable for wet and freeze-dried
materials once a sonication step had been carried out for reconstitution of the freeze-dried materials prior to extraction.
Homogeneity was assessed through replicate analysis of the phycotoxins (n = 10), and was found to be similar for wet and freeze-dried materials, for both hydrophilic and lipophilic toxins. Water
contents were determined for both wet and freeze-dried materials, and particle size was determined for the freeze-dried materials.
Stability was evaluated isochronously over eight months at four temperatures (−20, +4, +20 and +40 °C). The freeze-dried material
containing domoic acid was stable over the whole duration at all temperatures, while in the wet material domoic acid degraded
to some extent at all temperatures except −20 °C. In freeze-dried and wet materials containing lipophilic toxins, okadaic
acid, dinophysistoxin-2, azaspiracid-1 and azaspiracid-2 were stable over the whole duration at all conditions, while concentrations
of azaspiracid-3 changed significantly in both materials at some storage temperatures.
Figure Aliquots of freeze-dried and wet mussel tissue reference materials containing the various shellfish toxins examined in the
study 相似文献
150.
Microwave-assisted thermal desorption (MAD) coupled to headspace solid-phase microextraction (HS-SPME) has been studied for
in-situ, one-step, sample preparation for PAHs collected on XAD-2 adsorbent, before gas chromatography with mass spectrometric
detection. The PAHs on XAD-2 were desorbed into the extraction solution, evaporated into the headspace by use of microwave
irradiation, and absorbed directly on a solid-phase microextraction fiber in the headspace. After desorption from the SPME
fiber in the hot GC injection port, PAHs were analyzed by GC–MS. Conditions affecting extraction efficiency, for example extraction
solution, addition of salt, stirring speed, SPME fiber coating, sampling temperature, microwave power and irradiation time,
and desorption conditions were investigated. Experimental results indicated that extraction of 275 mg XAD-2, containing 10–200 ng
PAHs, with 10-mL ethylene glycol–1 mol L−1 NaCl solution, 7:3, by irradiation with 120 W for 40 min (the same as the extraction time), and collection with a PDMS–DVB
fiber at 35 °C, resulted in the best extraction efficiency. Recovery was more than 80% and RSD was less than 14%. Optimum
desorption was achieved by heating at 290 °C for 5 min. Detection limits varied from 0.02 to 1.0 ng for different PAHs. A
real sample was obtained by using XAD-2 to collect smoke from indoor burning of joss sticks. The amounts of PAHs measured
varied from 0.795 to 2.53 ng. The method is a simple and rapid procedure for determination of PAHs on XAD-2 absorbent, and
is free from toxic organic solvents. 相似文献