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1.
Exact solutions of the field equations of Nordtvedt’s theory for spatially flat FRW models with constant deceleration parameter
have been obtained. Singular solutions with (i) power-law (ii) exponential expansion have been studied in Nordtvedt’s theory
where the coupling parameterω is a function of the scalar fieldφ. 相似文献
2.
Experimental investigations on the ferroelectric liquid crystal, R-4′(1-butoxycarbonyl-1-ethoxy) phenyl 4-(4-octyloxy phenyl) benzoate (1BC1EPOPB) of large spontaneous polarization (P S(+) = 240?nC?cm?2), using dielectric and calorimetric techniques, are reported. The temperature range of 25.0–125.0°C has been chosen for dielectric measurements. Dielectric dispersion studies are carried out in the temperature range 45.0–75.0°C and in the frequency range 2?Hz to 2?MHz for the smectic A, smectic C* and smectic X phases. A new phase called ‘smectic X’ has been found around 56.3°C. The transition temperatures identified by the dielectric dispersion studies for different phases and those given by DSC techniques are in close agreement. 相似文献
3.
Summary Synthesis of MBAMT (3-methyl-4-benzylideneamino-5-mercapto-1,2,4-triazole) and its IR and NMR spectral data are reported. The high stability of the characteristically coloured chelates with Cu(II), Co(II), Ni(II), Pd(II), Pt(IV) and Rh(III) has been made the basis for their efficient ascending TLC separations on silica gel G layers, when present together. Results of four different solvent systems are included to assess efficient resolution of the chelates along with their limits of identification and separation. TLC separations, followed by the ring colorimetric determination of the six metal ions (as ternary mixtures) are tabulated.MBAMT=3-methyl-4-benzylideneamino-5-mercapto-1,2,4-triazole. 相似文献
4.
Consider a tandem queue model with a single server who can switch instantaneously from one queue to another. Customers arrive according to a Poisson process with rate λ . The amount of service required by each customer at the ith queue is an exponentially distributed random variable with rate μi. Whenever two or more customers are in the system, the decision as to which customer should be served first depends on the optimzation criterion. In this system all server allocation policies in the finite set of work conserving deterministic policies have the same expected first passage times (makespan) to empty the system of customers from any initial state. However, a unique policy maximizes the first passage probability of empty-ing the system before the number of customers exceeds K, for any value of K, and it stochastically minimizes (he number of customers in the system at any time t > 0 . This policy always assigns the server to the non empty queue closest to the exit 相似文献
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Microchimica Acta - Rapid separation and determination of chromium and vanadium valence states inμg quantities from their mixed solutions have been accomplished by the Weisz ring oven. Aqueous... 相似文献
7.
Yu Wang Guojun Liu Heng Hu Terry Yantian Li Amer M. Johri Xiaoyu Li Jian Wang 《Angewandte Chemie (International ed. in English)》2015,54(48):14291-14294
The dispersion into water of nanocapsules bearing a highly hydrophobic fluorinated internal lining yielded encapsulated air nanobubbles. These bubbles, like their micrometer‐sized counterparts (microbubbles), effectively reflected ultrasound. More importantly, the nanobubbles survived under ultrasonication 100‐times longer than a commercial microbubble sample that is currently in clinical use. We justify this unprecedented stability theoretically. These nanobubbles, owing to their small size and potential ability to permeate the capillary networks of tissues, may expand the applications of microbubbles in diagnostic ultrasonography and find new applications in ultrasound‐regulated drug delivery. 相似文献
8.
A method is reported here for calculating unsteady aerodynamics of hovering and flapping airfoil for two-dimensional flow
via the following improved methodologies: (a) a correct formulation of the problem using stream function (ψ) and vorticity
(ω) as dependent variables; (b) calculating loads and moment by a new method to solve the governing pressure Poisson equation
(PPE) in a truncated part of the computational domain on a nonstaggered grid; (c) accurate solution using high accuracy compact
difference scheme for the vorticity transport equation (VTE) and (d) accelerating the computations by using a high-order filter
after each time step of integration. These have been used to solve Navier–Stokes equation for flow past flapping and hovering
NACA 0014 and 0015 airfoils at typical Reynolds numbers relevant to the study of unsteady aerodynamics of micro air vehicle
(MAV) and insect/bird flight. 相似文献
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