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51.
A new procedure for the reduction of Preston tube data is introduced, based on the van Driest transformation. It appears to give results agreeing with the better calibration experiments, although a significant assumption in its derivation is violated.List of Symbols
M
s
Mach number sensed by Preston tube
-
M
Friction Mach number (=u/wall sound speed)
-
R
Gas constant
-
T
w
Wall temperature
-
d
Diameter of Preston tube
-
h
Height of effective centre of Preston tube
-
p
Preston tube pressure difference reading
-
p
i
Equivalent incompressible Preston tube reading
-
p
w
Wall pressure
-
r
Recovery factor (=0.896)
- u
Friction velocity (=[w/wall density]1/2)
-
Empirical constant allowing for departure from Crocco temperature-velocity correlation (=0.975)
-
Specific heat ratio
-
Fluid kinematic viscosity
-
w
Wall shear-stress 相似文献
52.
D. J. Mowbray L. Harris P. W. Fry A. D. Ashmore S. R. Parnell J. J. Finley M. S. Skolnick M. Hopkinson G. Hill J. Clark 《Physica E: Low-dimensional Systems and Nanostructures》2000,7(3-4)
The gain characteristics of InAs–GaAs self-assembled quantum dot lasers are studied using two complementary techniques. The modal gain is derived from a measurement of the normal incidence, inter-band photoconductivity. For a device containing a single layer of dots the maximum modal gain of the ground state transition is found to be insufficient for lasing action. As a consequence lasing occurs for excited state transitions, which have a larger oscillator strength, with the precise transition being dependent upon the device cavity length. The second technique uses the Hakki–Paoli method to determine the spectral and current dependence of the gain. A quasi-periodic modulation of the below threshold gain is observed. This modulation is shown to be responsible for the form of the lasing spectra, which consist of groups of lasing modes separated by non-lasing spectral regions. Possible mechanisms for this behaviour are discussed. 相似文献
53.
A. Kress F. Hofbauer N. Reinelt H.J. Krenner M. Bichler D. Schuh R. Meyer G. Abstreiter J.J. Finley 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):351
We demonstrate our ability to control and manipulate the optical modes in 2D Photonic Crystal Defect cavities and investigate their coupling to InGaAs self-assembled quantum dots. Our results enable us to probe the nature of individual cavity modes and directly investigate cavity QED phenomena. For the lowest mode volume cavities investigated, consisting of a single missing air hole within a hexagonal lattice, we have measured a clear Purcell enhancement of the light-matter interaction in the weak coupling regime. For QDs on-resonance with localized cavity modes this translates to a shortening of the quantum dot spontaneous emission lifetime by a factor 2 when compared to off-resonance dots. 相似文献
54.
Allgeier DE Herbert SA Nee R Schlecht KD Finley KT 《The Journal of organic chemistry》2003,68(12):4988-4990
The addition of arylsulfinic acids to 2-methyl-1,4-benzoquinone provides high yields of sulfones in a wide variety of solvents. The distribution of isomeric products obtained is strongly influenced by either (1) the acidity of aqueous solvents or (2) the water content of alcohol solvents. The distribution of isomeric products does not change in the various anhydrous, aprotic solvents examined. 相似文献
55.
A new perturbation approach is proposed that enhances the low‐order, perturbative convergence by modifying the zeroth‐order Hamiltonian in a manner that enlarges any small‐energy denominators that may otherwise appear in the perturbative expansion. This intruder state avoidance (ISA) method can be used in conjunction with any perturbative approach, but is most applicable to cases where small energy denominators arise from orthogonal‐space states—so‐called intruder states—that should, under normal circumstances, make a negligible contribution to the target state of interests. This ISA method is used with multireference Møller–Plesset (MRMP) perturbation theory on potential energy curves that are otherwise plagued by singularities when treated with (conventional) MRMP; calculation are performed on the 13Σ state of O2; and the 21Δ, 31Δ, 23Δ, and 33Δ states of AgH. This approach is also applied to other calculations where MRMP is influenced by intruder states; calculations are performed on the 3Πu state of N2, the 3Π state of CO, and the 21A′ state of formamide. A number of calculations are also performed to illustrate that this approach has little or no effect on MRMP when intruder states are not present in perturbative calculations; vertical excitation energies are computed for the low‐lying states of N2, C2, CO, formamide, and benzene; the adiabatic 1A1–3B1 energy separation in CH2, and the spectroscopic parameters of O2 are also calculated. Vertical excitation energies are also performed on the Q and B bands states of free‐base, chlorin, and zinc–chlorin porphyrin, where somewhat larger couplings exists, and—as anticipated—a larger deviation is found between MRMP and ISA‐MRMP. © 2002 Wiley Periodicals, Inc. J Comput Chem 10: 957–965, 2002 相似文献
56.
57.
Aguilar-Arevalo AA Bazarko AO Brice SJ Brown BC Bugel L Cao J Coney L Conrad JM Cox DC Curioni A Djurcic Z Finley DA Fleming BT Ford R Garcia FG Garvey GT Green C Green JA Hart TL Hawker E Imlay R Johnson RA Kasper P Katori T Kobilarcik T Kourbanis I Koutsoliotas S Laird EM Link JM Liu Y Liu Y Louis WC Mahn KB Marsh W Martin PS McGregor G Metcalf W Meyers PD Mills F Mills GB Monroe J Moore CD Nelson RH Nienaber P Ouedraogo S Patterson RB Perevalov D Polly CC Prebys E Raaf JL Ray H Roe BP 《Physical review letters》2008,100(3):032301
58.
59.
Muhammad Ghufran Rafique Dr. Jacob M. Remington Finley Clark Haochen Bai Dr. Violeta Toader Prof. Dmytro F. Perepichka Prof. Jianing Li Prof. Hanadi F. Sleiman 《Angewandte Chemie (International ed. in English)》2023,62(24):e202217814
Two-dimensional (2D) assemblies of water-soluble block copolymers have been limited by a dearth of systematic studies that relate polymer structure to pathway mechanism and supramolecular morphology. Here, we employ sequence-defined triblock DNA amphiphiles for the supramolecular polymerization of free-standing DNA nanosheets in water. Our systematic modulation of amphiphile sequence shows the alkyl chain core forming a cell membrane-like structure and the distal π-stacking chromophore block folding back to interact with the hydrophilic DNA block on the nanosheet surface. This interaction is crucial to sheet formation, marked by a chiral “signature”, and sensitive to DNA sequence, where nanosheets form with a mixed sequence, but not with a homogeneous poly(thymine) sequence. This work opens the possibility of forming well-ordered, bilayer-like assemblies using a single DNA amphiphile for applications in cell sensing, nucleic acid therapeutic delivery and enzyme arrays. 相似文献