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71.
张鹏 《组合机床与自动化加工技术》2003,(4):38-39
根据棱体成形车刀的设计理论,提出了一种利用三维造型技术将刀具廓形复杂的计算转变为一种直接通过截面获得的精确设计方法;并结合参数化设计技术和CAD/CAM集成技术实现了刀具廓形全面参数化设计和制造。 相似文献
72.
本文提出了双回转送进二辊冷轧管机凸轮理论轮廓曲线的新设计方法 ,其轮廓曲线加速度与跃度呈梯形 ,且跃度边界连续 ,给出了针对双回转送进二辊冷轧管机的两个过渡段具有等加速度和跃度的设计准则 相似文献
73.
74.
Compared with grinding, hard turning is competitive in many cases, with substantial benefits. However, hard turning applications are not preferred, due to the existence of the process-induced white layer on the component surface, which is often assumed to be detrimental to component life. Nevertheless, white layer properties have not been well understood or clearly defined, especially the properties of the white layer induced in hard turning as against grinding. A clear understanding of white layer properties will provide a solid physics basis for product performance analysis and useful data for process selection. In this study, benchmark hard turning and cylindrical grinding experiments were conducted to generate thick white layers for reliable measurement. It was found that the properties of white and dark layers by hard turning and grinding are fundamentally different in four aspects: surface structure characteristics, microhardness, microstructures, and chemical composition. A white layer is not untempered martensite in terms of retained austenite. Additionally, a thick white layer can be produced in grinding under certain conditions. 相似文献
75.
Significant progress has already been achieved in green manufacturing including dry and hard, often high-speed, machining technologies. For instance, the demand for higher productivity has resulted in the wider application of ceramic and PCBN tools with special multi-radii (wiper) geometry. This paper reports some important characteristics of the surface roughness produced in the turning of a hardened low-chromium alloy steel using mixed alumina–titanium carbon (TiC) ceramic cutting tools equipped with both conventional and wiper inserts. The characteristic geometrical features of surfaces obtained in both these turning operations have been assessed by means of representative two-dimensional (2D) surface roughness parameters, and some 3D visualizations, which allowed more complete characterization of the surface topography and prediction of its service properties. Results show that keeping equivalent feed rates, i.e. 0.1 mm/rev for conventional and 0.2 mm/rev for wiper tools, the surfaces obtained have similar 3D height roughness parameters, and comparable values of skew and kurtosis. At defined cutting parameters, surfaces produced by wiper tools contain blunt peaks with distinctly smaller slopes resulting in better bearing properties. Only marginal changes of Ra parameter were recorded during 15 min machining trials. 相似文献
76.
77.
DEFORMATIONBEHAVIOUROFCu-Zn-AlALLOYSANDITSEFFECTONTRANSFORMATIONHYSTERESISWangMingpu;XuGenyin;YinZhiming(DepartmentofMaterial... 相似文献
78.
A mathematical model is developed to predict particle velocity and temperature during high-velocity oxyfuel (HVOF) spraying.
This model accounts for internal heat conduction in powder particles; particle heating, fusion, cooling, and solidification;
the influence of particle morphology on thermal behavior; and the composite structure of the particles. Analytical results
are obtained that describe particle velocity and temperature variations. The dependence of fluid velocity on particle density
and volume fraction is shown. The results agree with empirically established HVOF spraying practice.
Physical Metal-lurgy—Materials Science 相似文献
79.
A new thermomechanical model of cutting applied to turning operations. Part I. Theory 总被引:1,自引:0,他引:1
In this paper, an analytical approach is used to model the thermomechanical process of chip formation in a turning operation. In order to study the effects of the cutting edge geometry, it is important to analyse its global and local effects such as the chip flow direction, the cutting forces and the temperature distribution at the rake face. To take into account the real cutting edge geometry, the engaged part in cutting of the rounded nose is decomposed into a set of cutting edge elements. Thus each elementary chip produced by a straight cutting edge element, is obtained from an oblique cutting process. The fact that the local chip flow is imposed by the global chip movement is accounted for by considering appropriate interactions between adjacent chip elements. Consequently, a modified version of the oblique cutting model of Moufki et al. [Int. J. Mech. Sci. 42 (2000) 1205; Int. J. Mach. Tools Manufact. 44 (9) (2004) 971] is developed and applied to each cutting edge element in order to obtain the cutting forces and the temperature distributions along the rake face. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening, the thermomechanical coupling and the inertia effects are taken into account in the modelling. The model can be used to predict the cutting forces, the global chip flow direction, the surface contact between chip and tool and the temperature distribution at the rake face which affects strongly the tool wear. Part II of this work consists in a parametric study where the effects of cutting conditions, cutting edge geometry, and friction at the tool–chip interface are investigated. The tendencies predicted by the model are also compared qualitatively with the experimental trends founded in the literature. 相似文献
80.
本文叙述了提高伺服飞锯机定尺精度所采用的两种方法,这两种方法目前都已应用在实际生产中,伺服飞锯机的定尺精度高于国际上通用的标准. 相似文献