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831.
A comprehensive numerical study of transient interchamber processes occurring when reaching the SPRE operational conditions
is carried out. A conjugate problem under consideration includes nonstationary operation of an igniter heating, ignition and
subsequent nonstationary and turbulent burning of a solid-propellant charge; nonstationary three-phase homo-heterogeneous
flow of combustion products in the combustion chamber, nozzle and downstream of the nozzle block of a rocket engine; motion
of a nozzle block cover. The calculation results are presented. 相似文献
832.
A numerical and analytical method for constructing a shape of the axisymmetric body streamlined with jet blowout by the specified
velocity distribution along its meridian section is proposed. The foundation of the method is the iteration process based
on the solutions of an inverse problem in the plane case and a primal problem for the axisymmetric body. A program realizing
the iteration process is set up and examples of numerical calculations are given. 相似文献
833.
A recursive method for calculating decoupling zeroes in the linear multiconnected dynamic system based on the application
of matrix canonization techniques is proposed. Its essence is that the problem dimension is successively decreased and reduced
to finding eigenvalues of some matrix. The results obtained can be used to check controllability and observability as well
as to calculate uncontrollable and unobservable modes of the dynamic system. 相似文献
834.
V. R. Rubinskii S. P. Khrisanfov V. Yu. Klimov A. V. Kretinin 《Russian Aeronautics (Iz VUZ)》2010,53(1):81-86
The numerical results are presented for the case of coaxial-jet supply at the different ratio of mass component velocities
at the combustion chamber inlet with the constant and variable relationship of oxygen-methane components. The experimental
investigations of coaxial-jet mixing elements as part of the model setup chamber operating on corrosive producer gas and gaseous
methane were carried out. A qualitative pattern of the $
\overline {\rho u}
$
\overline {\rho u}
parameter influence on the chamber economic feasibility was obtained: as $
\overline {\rho u}
$
\overline {\rho u}
decreases, the combustion efficiency coefficient grows. 相似文献
835.
Manabu Sugimoto Makoto Ishii Izumi C. Mori Shagimardanova Elena Oleg A. Gusev Makoto Kihara Takehiro Hoki Vladimir N. Sychev Margarita A. Levinskikh Natalia D. Novikova Anatoly I. Grigoriev 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Barley seeds were exposed to outer space for 13 months in a vented metal container without a climate control system to assess the risk of physiological and genetic mutation during long-term storage in space. The space-stored seeds (S0 generation), with an 82% germination rate in 50 seeds, lost about 20% of their weight after the exposure. The germinated seeds showed normal growth, heading, and ripening. The harvested seeds (S1 generation) also germinated and reproduced (S2 generation) as did the ground-stored seeds. The culm length, ear length, number of seed, grain weight, and fertility of the plants from the space-stored seeds were not significantly different from those of the ground-stored seeds in each of the S0 and S1 generation. Furthermore, the S1 and S2 space-stored seeds respectively showed similar β-glucan content to those of the ground-stored seeds. Amplified fragment length polymorphism analysis with 16 primer combinations showed no specific fragment that appears or disappears significantly in the DNA isolated from the barley grown from the space-stored seeds. Though these data are derived from nine S0 space-stored seeds in a single exposure experiment, the results demonstrate the preservation of barley seeds in outer space for 13 months without phenotypic or genotypic changes and with healthy and vigorous growth in space. 相似文献
836.
R. T. Ripetskyj N. A. Kit Ch. I. Chaban 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,23(12):2005-2010
In dark-grown plantlets of the moss, Pottia intermedia, negatively gravitropic secondary protonemata differentiate from the superficial cells of leafy shoots. When transferred to the light, distal parts of the protonemata nearest to the apical cells begin to ramify and the apical cells of the side branches as well as of the main protonemal filaments often differentiate as buds. Dark-grown protonemata were oriented horizontally and illuminated from below with white light of different intensities. Only light with an intensity of 4.5 μmol·m−2·s−1 was sufficient to induce: (a) phototropism in the apical cells, (b) light-directed initiation of branch primordia, and (c) directed growth of side branches and bud differentiation. Apical cells illuminated with light of lower (0.03–0.37 μmol·m−2·s−1) intensity grew upwards (i.e., away from the light). It was shown that this upward growth was determined by the action of gravity. Although initiation of branch primordia was only slightly affected, their growth was strongly stimulated on the upper side of the protonemata. 相似文献
837.
S I Bartsev V A Okhonin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,24(3):407-412
To develop and design Life Support Systems it is necessary to evaluate their reliability. However direct experiments take much time, are very expensive, and therefore are practically impossible. Promising way is to use approximate estimates of reliability, which need essentially fewer amounts of experimental data. Two types of estimates of Life Support System reliability--additive and multiplicative ones are considered in the paper. Additive estimate is based on the assumption that total system failure probability is low and therefore it can be considered as the sum of failure probability of separate units. Additive approach allows obtaining near lower-bounded estimate of failure probability. Multiplicative estimate allows evaluating the possibility of system catastrophe due to simultaneous effect of several factors when each of them separately is not dangerous. Evaluation shows that the possible error of reliability forecast increases with the increasing of number of external factors faster than exponential function. An illustration of the ecological similarity approach as promising tool for providing estimation of full-scale system reliability by means the set of small similar experimental models. 相似文献
838.
Crewmembers play an important role in ensuring the efficiency of "crew-spacecraft" system. However, despite of the fact that crewmembers are well trained and highly motivated persons, extreme flight factors may influence negatively on their reliability, and lead to human error occurrence. Therefore, working out methods of human error prevention is very significant to increase crewmember's performance reliability. Human error can occur in the operation of systems for a number of reasons. Within the framework of the present investigation, with use the data collected during "Mir" station missions, the significant (p<0.05) positive correlation of crewmembers errors (CE) frequency with their psychophysiological state (PPS), and work and rest schedule (WRS) intensity has been revealed. Differently, the higher WRS intensity, the crewmember's PPS is worse, and CE frequency is higher. This finding has been based on substantiations of the approach to human reliability management. Its essence will consist of the following: reducing WRS intensity, we thus can improve a crewmember's PPS and, accordingly, reduce CE frequency. This approach is discussed in the paper. 相似文献
839.
I.V. Arkhangelskaja 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,34(12):2723-2728
In the present work the possibility of the fractal analysis application for GRB temporal profiles was studied. We have analysed the 4B revised BATSE catalog: temporal profiles of GRB with t90 < 3 s (287 short and 100 intermediate) were studied on TTE data, a sample of 278 intermediate GRB with t90 3 s were studied on DISCSC data. An analysis of the background fractal dimension distributions obtained using TTE and DISCSC data (143 and 110 background regions, respectively), indicates that for both datasets background fractal dimensions Dbgr = 1.5 that the fractal dimension distributions obtained by using these data can be processed simultaneously. The change of the fractal index Dbgr for Poisson statistics – dominated sets with different coefficients of error in counting (up to 10) was studied and Dbgr = 1.5. The ranges of fractal dimension (0.80 D 2.25 for short and 0.85 D 2.01 for intermediate GRB) are shifted over range for theoretical fractal curve (1 < D < 2) due to the finite detector time resolution. There are four subgroups in fractal dimension distribution for short GRB (D = 1.05 ± 0.03, D = 1.31 ± 0.05, D = 1.51 ± 0.04, D = 1.90 ± 0.03) and six subgroups for intermediate one (D = 1.05 ± 0.09, D = 1.24 ± 0.08, D = 1.44 ± 0.07, D = 1.51 ± 0.08, D = 1.64 ± 0.07, D = 1.91 ± 0.1). Time profiles with fractal dimension smaller then background can be obtained by using models with many short chaotic processes in sources, for example, fireball model with shock waves. The range of fractal dimensions for the modelled temporal profiles is 1.213 D 1.400, which can correspond to subgroups of short and intermediate GRB with D = 1.31 and D = 1.24; moreover, the fractal dimension of a simulated indented event and GRB990208 are equal within the error limits for some model parameters and it is possible to obtain smooth temporal profiles with D = Dbgr. 相似文献
840.