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531.
532.
提出了水平轴风力机叶片的优化设计模型,该模型以风轮平均年能量输出最大为设计目标,并将风速的概率分布考虑进来。为了获得较好的优化结果,首先采用PROPID程序对叶片进行反设计,获得较好性能的叶片几何,在此基础上,运用遗传算法进行搜索寻优,这样不仅减小了搜索的范围,也降低了搜索的时间。对叶片面积附加约束,以获得符合实际的叶片,采用5阶贝塞尔函数在设计点之间进行插值,以获得光滑的几何外形。利用该方法优化设计了600kW风力机叶片。与已有叶片相比,优化结果显示了明显的优越性,验证了该优化方法的有效性和实用性。 相似文献
533.
Two strategies extended the single-cascade methods from a compressible three-dimensional inverse method for radial and mixed flow turbomachines to two three-dimensional multi-cascade co-design methods for single-stage centrifugal compressors.These two three-dimensional methods and a typical quasi-three-dimensional streamline curvature through-flow inverse method were employed to design the same subsonic high-speed single-stage centrifugal compressors.The compressor performances were simulated by a commercial Reynolds averaged Navier-Stokes (RANS) equations solver.The studies show that two three-dimensional co-design methods are reasonable and feasible.It was found that:firstly the blade camber angle designed by the three-dimensional methods was larger than that designed by the quasi-three-dimensional method;and secondly with regard to two three-dimensional methods with different boundary conditions,the co-design result differences between the diffusers were small,but those between the deswirlers were relatively large. 相似文献
534.
《中国航空学报》2021,34(5):510-522
To strengthen Specific Energy-Absorption (SEA) behavior of Sandwich Composite Structure (SCS), a kind of light-weight vertical stiffener is proposed for the corrugated core. The vertical stiffener, embedded in the corrugated core, can not only absorb part of energy but also simultaneously enhance Energy-Absorption (EA) of other components. The Hashin damage model considering the shear stress and ductile damage model is adopted to predict the failure of carbon fiber face-sheets and aluminum-core, respectively. The perfect bonding is modeled for interfaces between the face-sheet and core due to little realistic debonding. The finite element model is verified by available data of conventional SCS. To obtain more design ideas, several stiffeners with different thicknesses, numbers, and positions are investigated. From the predicted results, both the flexural load and deformation of SCS correlate well with experimental results. It is highlighted that the SCSs with different vertical stiffeners exhibit 9.74%–58.48% higher SEA than the SCS without stiffener. The complex reinforcement mechanisms are extensively revealed by underlying coupling EA and deformation mechanisms. Structural parameter analysis shows that the thickness and number have significant effects on the flexural behavior and SEA of reinforced SCS. 相似文献
535.
536.
Jinlu Hu Liang Jin Xiaojuan Wang Wenkai Cai Yongding Liu Gaohong Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The present study investigated the physiological and biochemical characteristics of Scytonema javanicum, a pioneer species isolated from desert biological crusts, under salinity stress. Pigment analysis showed that salinity decreased chlorophyll a and phycocyanin content, while low salinity increased carotenoid concentration and high salinity decreased carotenoid concentration. Salinity also inhibited CO2 assimilation rate and photosynthetic oxygen evolution in this cyanobacterium. Chlorophyll a fluorescence transient parameters (φPo, φEo, ψO, RC/ABS, RC/CS, PIABS, and PICS) were decreased under salt stress, while dVo/dto(Mo), Vj and φDo were increased. The decrease of ETRmax and Yield and the change of chlorophyll a fluorescence transients showed that salt stress had an important influence on photosynthesis. These results indicated that the effects of salinity stress on photosynthesis in S. javanicum may depend on the inhibition of electron transport and the inactivation of the reaction centers, but this inhibition may occur in the electron transport pathway at the PSII donor and acceptor sites. 相似文献
537.
纤维增强树脂基复合材料的吸湿性和湿变形 总被引:3,自引:0,他引:3
阐述了纤维增强树脂基复合材料的吸湿与湿变形机理及其影响因素,从环境、材料和工艺3个方面,总结了环境温度、相对湿度、纤维、树脂基体、纤维-基体界面以及铺层方式对复合材料吸湿性与湿变形的影响,并提出了降低纤维增强树脂基复合材料吸湿率与湿变形的途径。 相似文献
538.
多目标自然层流翼型反设计方法 总被引:2,自引:0,他引:2
进行了基于扰动放大N-因子的目标压力分布设计方法的多目标自然层流(NLF)翼型反设计方法研究。流场分析和转捩位置计算用XFOIL程序,大大减少了计算花费。用N-因子设计方法进行有NLF范围要求和满足气动约束的目标压力计算,压力恢复段的压力分布用Stratford分离准则来进行设计。用基于响应面方法的优化方法来进行反设计计算,使用不含二阶交叉项的二次多项式模型的响应面模型,大大减少了构造模型所需的试验次数;设计空间内试验点的选取满足D-优化准则。根据设计目标的设计状态,进行了多目标翼型反设计。计算结果表明,设计结果的层流范围和设计目标基本吻合,该方法可以用于NLF翼型的多目标反设计中。 相似文献
539.
针对一类未知非线性大时延系统,利用SVM特有的表达任意非线性映射能力,辨识得到非线性系统的α阶逆模型,然后将其串在原系统前组成SVMα阶伪线性复合系统。以此复合系统为被控对象,用预测控制方法实现对其有效控制。该方法不仅将非线性系统简化成伪线性系统,而且具有良好的控制效果,控制器设计简单。 相似文献
540.
利用物体抓取任务中所有五个手指运动的运动学分析结果,结合LeapMotion 运动跟踪设备的特点和
逆运动学,提出了一种简单而有效的灵巧虚拟手抓取交互方法,使用户在虚拟环境中,通过一只灵巧的虚拟手
作为化身,在不进行手指弯曲运动跟踪的情况下,即可自然地到达并抓取数字三维物体。验证结果表明,所提
出的方法比传统的基于正向运动学的虚拟抓取方法具有一定的优势。 相似文献