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141.
A 100 MWt reactor design has been conceived to support flux level of the order of 1015 n/cm2/s in selected flux trap zones. The physics design considers high enriched metallic alloy fuel in the form of annular plates
placed in a D2O moderator tank in a hexagonal lattice arrangement. By choosing a tight lattice pitch in the central region and double the
lattice pitch in the outer region, it is possible to have both high fast flux and thermal flux trap zones. By design the flux
level in the seed fuel has been kept lower than in the high flux trap zones so that the burning rate of the seed is reduced.
Another important objective of the design is to maximize the time interval of refueling. As against a typical refueling interval
of a few weeks in such high flux reactor cores, it is desired to maximize this period to as much as six months or even one
year. This is possible to achieve by eliminating the conventional control absorbers and replacing them with a suitable amount
of fertile material loading in the reactor. Requisite number of seedless thorium-aluminum alloy plates are placed at regular
lattice locations vacated by seed fuel in alternate fuel layers. It is seen that these thorium plates are capable of acquiring
asymptotic fissile content of 14 g/kg in about 100 days of irradiation at a flux level of 8 × 1014 n/cm2/s. In summary, the core has a relatively higher fast flux in the central region and high thermal flux in the outer region.
The present physics design envisages a flat core excess reactivity for the longest possible cycle length of 6 months to one
year. It is also possible to modify the design for constant subcriticality for about the same period or longer duration by
considering neutron spallation source at the centre and curtailing the power density in the inner core region by shielding
it with a layer of thoria fuel loading.
相似文献
142.
Mrinmay Pal Somnath Bandyopadhyay Palas Biswas Rimlee Debroy M. C. Paul Ranjan Sen Kamal Dasgupta S. K. Bhadra 《Optical and Quantum Electronics》2007,39(14):1231-1243
In this paper, gain flatness is studied for simultaneous 16-ITU-T channel amplifications at C-band (1,532–1,558 nm) in a single
stage EDFA for WDM application at different average inversion levels. The inversion levels are varied due to the change of
the input signal levels from the targeted operating point and also for dropping few numbers of channels. Specially designed
gain flattening filter (GFF) is used in order to get the flat gain with gain variation ±0.5 dB for −20 dBm/ch input signal
power (total input signal power is −8.0 dBm) at a fixed average inversion level which is maintained by proper selection of
optimum fibre length and pump power. A specific loss spectrum of GFF is obtained by writing a chirped fibre Bragg grating
of length 20 mm. Gain variations are studied by changing the total input signal levels from −8.0 dBm to −20.0 dBm and maintained
within 20.0 ± 0.5 dB by using automatic gain control (AGC) circuit. About 15 out of 16 channels are dropped and observed ±
0.5 dB gain-variation which is an important parameter in optical network system. 相似文献
143.
M. Sreenivasulu K. Arun KumarK. Sateesh Reddy K. Siva KumarP. Rajender Kumar K.B. ChandrasekharManojit Pal 《Tetrahedron letters》2011,52(6):727-732
A rapid, economic, and high yielding methodology has been developed for hydroacylation/reduction of activated ketones by using 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride as a catalyst in combination with triethylamine. The reaction proceeded at an ambient temperature via generating N-heterocyclic carbene in situ that interacted with the (hetero)aryl aldehyde employed. While the reduction of ketones takes place in MeOH, the hydroacylation process was found to be effective in THF for both electron rich and deficient aldehydes. 相似文献
144.
We prove a uniqueness theorem for two non-constant meromorphic functions sharing three values which improves a recent result of T.C. Alzahary. As a consequence of our main result we also improve a theorem of G. Brosch. 相似文献
145.
146.
147.
148.
Low-temperature CO2 plasma is used for the treatment of poly-ethersulfone (PES), polyamide (PA) and poly-phenylene ethersulfone (PPE) ultrafiltration membranes. This has led to significant enhancement of the wetting characteristics of the membrane surface as is shown by contact angle measurements and Fourier transform infrared (FTIR) spectrum analysis of the treated membranes. Changes in the physical characteristics of the surface, such as tensile property, surface roughness, etc. are quantified by tensile strength measurement and atomic force microscopy (AFM), respectively. An increase in the measured values of the di-electric constants further highlights the hydrophilic modification of the surface. A series of ultrafiltration experiments using a BSA solution of known concentration under different operating conditions is performed and the deposition thicknesses over the membrane surface during ultrafiltration are measured directly using image analyzing microscopy. The results clearly demonstrate that a plasma treated PES membrane is more hydrophilic with smoother surface and resists fouling leading to significant enhancement of permeate flux. 相似文献
149.
Palash B Pal 《Pramana》2000,54(1):79-91
I start by defining the cosmological parameters H
0, Θ
m
and ΘA. Then I show how the age of the universe depends on them, followed by the evolution of the scale parameter of the universe
for various values of the density parameters. Then I define strategies for measuring them, and show the results for the recent
determination of these parameters from measurements on supernovas of type 1a. Implications for particle physics is briefly
discussed at the end. 相似文献
150.