全文获取类型
收费全文 | 1992篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
航空 | 988篇 |
航天技术 | 368篇 |
综合类 | 2篇 |
航天 | 637篇 |
出版年
2022年 | 5篇 |
2021年 | 22篇 |
2019年 | 10篇 |
2018年 | 170篇 |
2017年 | 149篇 |
2016年 | 48篇 |
2015年 | 31篇 |
2014年 | 36篇 |
2013年 | 49篇 |
2012年 | 75篇 |
2011年 | 167篇 |
2010年 | 152篇 |
2009年 | 182篇 |
2008年 | 158篇 |
2007年 | 156篇 |
2006年 | 22篇 |
2005年 | 78篇 |
2004年 | 37篇 |
2003年 | 28篇 |
2002年 | 20篇 |
2001年 | 39篇 |
2000年 | 21篇 |
1999年 | 12篇 |
1998年 | 27篇 |
1997年 | 11篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 26篇 |
1993年 | 15篇 |
1992年 | 18篇 |
1991年 | 4篇 |
1989年 | 14篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 26篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 16篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1972年 | 8篇 |
1968年 | 6篇 |
1967年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有1995条查询结果,搜索用时 46 毫秒
961.
The method of improving the positional accuracy of the airborne vehicle that moves along a great circle path is considered due to the analytical three-dimensional projection of its current coordinate position, determined from the measurements of the satellite navigation system under the conditions of high-amplitude noise to the true guide path. 相似文献
962.
Thermal and electric structures of diffusion coaxial jet flames determined experimentally are presented. The Burke-Shumann
problem is solved taking into account electrostatic forces appearing under imposition of an external electric field on the
flame. The excessive concentration of negative charges in the flame plasma with oxidizer deficiency is evaluated. 相似文献
963.
Yu.A. Berkovich S.O. SmolyaninaN.M. Krivobok A.N. ErokhinA.N. Agureev N.A. Shanturin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
A Manned Mars Mission scenario had been developed in frame of the Project 1172 supported International Science & Technology Center in Moscow. The Mars transit vehicle (MTV) supposed to have a crew of 4–6 with Pilot Laboratory compartment volume of 185 m3 and with inner diameter of 4.1 m. A vegetable production facility with power consumption up to 10 kW is being considered as a component of the life support system to supply crew members by fresh vegetables during the mission. Proposed design of conveyor-type plant growth facility (PGF) comprised of 4-modules. Each module has a cylindrical planting surface and spiral cylindrical LED assembly to provide a high specific productivity relative to utilized onboard resources. Each module has a growth chamber that will be from 0.7 m to 1.5 m in length, and a crop illuminated area from 1.7 m2 to 4.0 m2. Leafy crops (cabbage, lettuce, spinach, chard, etc.) have been selected for module 1, primarily because of the highest specific productivity per consumed resources. Dietitians have recommended also carrot crop for module 2, pepper for module 3 and tomato for module 4. The maximal total PGF light energy estimated as 1.16 kW and total power consumption as about 7 kW. The module 1 characteristics have been calculated using own experimental data, information from the best on ground plant growth experiments with artificial light were used to predict crop productivity and biomass composition in the another modules. 4-module PGF could produce nearly 0.32 kg per crew member per day of fresh edible biomass, which would be about 50% of recommended daily vegetable supplement. An average crop harvest index is estimated as 0.75. The MTV food system could be entirely closed in terms of vitamins C and A with help of the PGF. In addition the system could provide 10–25% of essential minerals and vitamins of group B, and about 20% of food fibers. The present state of plant growth technology allows formulating of requirements specification for the flight-qualified modules. 相似文献
964.
There have been many significant advances in understanding magnetic field reconnection as a result of improved space measurements
and two-dimensional computer simulations. While reviews of recent work have tended to focus on symmetric reconnection on ion
and larger spatial scales, the present review will focus on asymmetric reconnection and on electron scale physics involving
the reconnection site, parallel electric fields, and electron acceleration. 相似文献
965.
A. A. Inozemtsev V. G. Avgustinovich V. V. Tsatiashvili 《Russian Aeronautics (Iz VUZ)》2010,53(4):436-442
Results of numerical simulation and principles of designing a mixer in the secondary zone of the flame tube when adjusting
the rich-lean combustion chamber emission in the gas turbine engines are presented. 相似文献
966.
We experimentally confirmed the effect when the wave resistance of rough-wall plane channels, generated while the walls are
streamlined by a supersonic gas flow, reaches the extreme values. The experiments were conducted on a differential setup by
comparing the tests of flat and round sonic nozzles. The results of the experiment justified the developed method of calculating
the wave resistance of the plane channel with sawtooth wall relief. 相似文献
967.
The information on the project being developed in Brazil for a flight to binary or triple near-Earth asteroid is presented.
The project plans to launch a spacecraft into an orbit around the asteroid and to study the asteroid and its satellite within
six months. Main attention is concentrated on the analysis of trajectories of flight to asteroids with both impulsive and
low thrust in the period 2013-2020. For comparison, the characteristics of flights to the (45) Eugenia triple asteroid of
the Main Belt are also given. 相似文献
968.
D. Sh. Shirapov 《Cosmic Research》2009,47(5):361-367
Dynamics of changes of the electric fields in the daytime and nighttime sectors of the high-latitude ionosphere is studied.
The following facts are demonstrated: (a) With the onset of active phases of substorms, a decrease occurs in the value of the electric potential difference in the
daytime sector. It is especially abrupt with the onset of the expansion phase, which is related to a decrease and the end
of reconnection at the dayside magnetopause. (b) With the onset of active phases of substorms, an increase in the value of the electric potential difference in the nighttime
sector occurs. It is sharply intensified with the onset of the expansion phase, this fact being caused by the intensification
of the reconnection in the nighttime magnetotail. (c) There exists a relation, close to a functional dependence, between the values of the electric potential differences in the
nighttime sector and | AL | index. 相似文献
969.
Kopytenko Yu. A. Petrova A. A. Guriev I. S. Labetsky P. V. Latysheva O. V. 《Cosmic Research》2021,59(3):143-156
Cosmic Research - This paper presents the results of a study of the informativity of the anomalies of the modulus and components of the Earth’s magnetic field in near-Earth space in the... 相似文献
970.