全文获取类型
收费全文 | 133篇 |
免费 | 10篇 |
国内免费 | 10篇 |
专业分类
航空 | 96篇 |
航天技术 | 41篇 |
综合类 | 7篇 |
航天 | 9篇 |
出版年
2024年 | 1篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 10篇 |
2011年 | 7篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 13篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1990年 | 1篇 |
1984年 | 2篇 |
排序方式: 共有153条查询结果,搜索用时 296 毫秒
51.
52.
对生产增强氟塑料的原材料P202和FR104两种聚四氟乙烯树脂性能进行了对比,采用“干法”制备工艺并对工艺参数进行改进,生产出FS-20d和FS-35d增强氟塑料。生产制品测试结果表明:“干法”制备工艺配方稳定、生产工艺稳定,制品的耐磨性能、耐高温性能、致密性、均匀性和相分散性均优于“湿法”制备工艺制品。 相似文献
53.
Leen Decin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Cool objects glow in the infrared. The gas and solid-state species that escape the stellar gravitational attraction of evolved late-type stars in the form of a stellar wind are cool, with temperatures typically ?1500 K, and can be ideally studied in the infrared. These stellar winds create huge extended circumstellar envelopes with extents approaching 1019 cm. In these envelopes, a complex kinematical, thermodynamical and chemical interplay determines the global and local structural parameters. Unraveling the wind acceleration mechanisms and deriving the complicated structure of the envelopes is important to understand the late stages of evolution of ∼97% of stars in galaxies as our own Milky Way. That way, we can also assess the significant chemical enrichment of the interstellar medium by the mass loss of these evolved stars. The Herschel Space Observatory is uniquely placed to study evolved stars thanks to the excellent capabilities of the three infrared and sub-millimeter instruments on board: PACS, SPIRE and HIFI. In this review, I give an overview of a few important results obtained during the first two years of Herschel observations in the field of evolved low and intermediate mass stars, and I will show how the Herschel observations can solve some historical questions on these late stages of stellar evolution, but also add some new ones. 相似文献
54.
The Dark Matter Particle Explorer (DAMPE) mission is one of the five scientific space science missions within the framework of the Strategic Pioneer Program on Space Science of the Chinese Academy of Science (CAS) approved in 2011. The main scientific objective of DAMPE is to detect electrons and photons in the range of 5GeV-10TeV with unprecedented energy resolution (1.5% at 100GeV) in order to identify possible Dark Matter (DM) signatures. It will also measure the flux of nuclei up to above 500TeV with excellent energy resolution (40% at 800GeV), which will bring new insights to the origin and propagation high energy cosmic rays. With its excellent photon detection capability, the DAMPE mission is well placed for new discoveries in high energy-ray astronomy as well. 相似文献
55.
以某型带缘板阻尼块涡轮叶片为对象,采用二维整体-局部统一滑动模型,编制涡轮叶片振动响应分析程序。在此基础上系统地计算不同参数时带缘板阻尼块叶片的振动响应,分析了正压力、外激励对减振效果的影响。算例分析表明:同一外激励下,存在一最佳正压力可以使系统减振效果比较好;正压力不变时,外激励幅值大小的变化对叶片减振效果有较大影响;另外阻尼块对叶片起到调频作用。 相似文献
56.
带弹支干摩擦阻尼器的转子振动控制 策略和方法 总被引:4,自引:3,他引:1
根据弹支干摩擦阻尼器的特点,提出弹支干摩擦阻尼器控制转子振动的方案,建立了基于主动弹支干摩擦阻尼器的比例积分控制(PI控制)和连续增益调度比例积分控制(连续GSPI控制)方法,对两种控制方法控制转子通过临界转速的振动进行了理论分析、数值仿真和试验验证,并分析了其特点. 相似文献
基于接触力学理论和线性互补问题(LCP)的算法,给出了一种含接触、碰撞以及对称和非对称Coulomb干摩擦的平面运动刚体动力学的建模与数值计算方法.将研究对象视为刚体,考虑物体接触点的局部变形,将物体间的法向接触力表示成嵌入量与嵌入速度的非线性函数;物体间的摩擦定律采用对称或非对称Coulomb干摩擦模型.首先,为了用数值方法确定粘滞与滑移(stick-slip)运动状态的切换,本文利用摩擦余量、接触点的正向和负向相对加速度等概念,给出了该摩擦定律的互补条件和互补关系式.然后,利用事件驱动法,将由于摩擦引起的stick-slip运动状态切换的判断及粘滞(stick)状态下接触点静摩擦力的计算问题转化成线性互补问题的求解.最后,通过数值算例分析了含对称与非对称Coulomb干摩擦平面运动刚体的动力学特性,并说明了该算法的有效性. 相似文献
58.
In this paper, we give a review of direct detection searches reported by the DAMA (China as a Co-I), and indirect detection searches reported by the ATIC (China as a Co-I). We also outline the future plans of dark matter search in China. 相似文献
59.
O.V. Melnyk I.B. Vavilova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
We have analyzed a sample of 7000 galaxies in the Local Supercluster (LS) (V < 3100 km/s) selected from the LEDA database [Makarov, D.I., Karachentsev, I.D. A new catalogue of multiple galaxies in the local supercluster small galaxy groups. Small Galaxy Groups ASP Confer. Ser. 209, 40–46, 2000]. We have derived physical properties of poor LS groups selected by dynamical and 3D-Voronoi tessellation methods. Median values of mass-to-luminosity ratios for poor LS groups selected by these methods are 50 M⊙/L⊙ and 34 M⊙/L⊙, respectively. Physical parameters of LS galaxy triplets in comparison with other samples were evaluated. We suggest that the Dressler effect is present even in such poor groups as galaxy triplets. The data suggest that dark matter haloes are associated with the individual galaxies for LS triplets, which we find are dynamically younger systems. This contrasts with the properties of the Interacting and Northern & Southern triplet samples. For these two samples, the data suggest that the dark matter resides in a common halo. The median values of the mass-to-luminosity ratios for LS triplets, Northern & Southern triplets, and Interacting triplets are 35 M⊙/L⊙, 47 M⊙/L⊙, and 13 M⊙/L⊙, respectively. 相似文献
60.
提出一种高效的多谐波分析方法,以用于研究失谐对带有叶间干摩擦阻尼的叶盘系统共振特性的影响规律.该方法可准确预测叶盘系统在频域的受迫响应,其有效性用数值积分法进行了验证.利用该方法对带有叶间干摩擦阻尼的叶盘受迫振动响应进行了仿真计算,分析了叶盘系统在谐调和失谐两种情况下受耦合强度、黏性阻尼和干摩擦阻尼等系统参数影响下的共振特性.结果表明,提出的多谐波分析法能够高效地研究失谐对带有叶间干摩擦阻尼的叶盘系统共振响应的影响特征,尤其适合考虑各种系统参数的综合影响. 相似文献