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271.
LIANG Jianduan LIN Shuzhi Institute of Metal Research Academia Sinica Shenyang China Professor Institute of Metal Research Academia Sinica Shenyang China 《金属学报(英文版)》1989,2(10):284-289
Experiments clarified that application of the maximum entropy method to calculate the RDF(radial distribution function)of the Ni-P amorphous alloy from fewer data of its X-raydiffraction data shows a higher resolution and good consistent with known results.It is be-lieved that this method is available for the analysis of amorphous structure. 相似文献
272.
合金元素对Zr基大块非晶晶化行为的影响 总被引:4,自引:1,他引:4
利用准晶的共轭结构模型构造出了Zr基非晶合金中准晶相的原子结构模型,用递归方法研究了合金元素对非晶晶化过程的影响.结果表明:Zr基非晶合金析出的准晶相存在Zr6Ni,Ni6Zr2种结构,Ni6Zr结构优先析出;合金元素Ag,Pd,Pt,Au固溶于准晶中时,占据Cu,Ni原子的位置,增大近邻原子间的相互作用,这从电子理论角度解释了合金元素Ag,Pd,Pt,Au稳定地促进二十面体准晶(I)相析出的事实. 相似文献
273.
Dong-il Shin François Gitzhofer Christian Moreau 《Journal of Thermal Spray Technology》2007,16(1):118-127
Metal-based thermal barrier coatings (MBTBCs) have been produced using high frequency induction plasma spraying (IPS) of iron-based
nanostructured alloy powders. The study of MBTBCs has been initiated to challenge issues associated with current TBC materials
such as difficult prediction of their “in-service” lifetime. Reliability of TBCs is an important aspect besides the economical
consideration. Therefore, the study of MBTBCs, which should posses higher toughness than the current TBC materials, has been
initiated to challenge the mechanical problems of ceramic-based TBCs (CBTBCs) to create a new generation of TBCs. The thermal
diffusivity (TD) (α) properties of the MBTBCs were measured using a laser flash method, and density (ρ) and specific heat
(C
p) of the MBTBCs were also measured for their thermal conductivity (k) calculation (k = αρ
C
p). 相似文献
274.
研究了经不同低频脉冲电流密度退火的Co66.3Fe3.7Si12B18非晶薄带的巨磁阻抗(GMI)效应。结果表明,在低频脉冲电流下,巨磁阻抗效应的大小与退火电流密度密切相关。非晶带的GMI变化率△Z/Z先随退火电流密度的增加而增强,当电流密度为104A/mm^2时,△Z/Z达到最大值53.8%,此后随电流密度增大,GMI变化率开始减小。对脉冲电流退火影响巨磁阻抗效应的机制作了定性分析。并分析了由脉冲电流退火在材料内感生的横向各向异性场凤对GMI效应的影响,发现HK有利于提高GMI效应的峰值,但同时存在一个临界值,当超过这个值时,GMI效应的峰值减弱。 相似文献
275.
276.
Advances in fabricating superplastically formed and diffusion bonded components for aerospace structures 总被引:1,自引:0,他引:1
Larry D. Hefti 《Journal of Materials Engineering and Performance》2004,13(6):678-682
Superplastic forming and diffusion bonding (SPF/DB) production hardware is being fabricated today for aerospace applications.
Metal tooling is being used to bring the titanium sheets into contact so diffusion bonding can occur. However, due to material
sheet and tooling tolerances, good bond quality is difficult to achieve over large areas. A better method for achieving DB
is to use “stop-off” inside sealed sheets of titanium, which constitutes a pack, and then the pack is bonded using external
gas pressure. A good method for heating the pack for this process is to use induction heating. Components using “stop-off”
that were diffusion bonded first and then superplastically formed have shown much better bond quality than components that
were produced using matched metal tooling. This type of tooling has been successful at bonding small areas as long as the
exerted pressure is concentrated on the area where bonding is required. Finite element modeling is providing weight effect
solutions for titanium SPF/DB aerospace structures.
This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing
Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium
was organized by Daniel G. Sanders, The Boeing Company. 相似文献
277.
对本科生导师制的思考 总被引:4,自引:0,他引:4
实行本科生导师制可以改变中国高校人才培养模式 ,进一步深化中国高等教育教学改革 ,培养出大批具有丰富个性的杰出人才。本科生导师的主要责任是培养学生的自学和独立思考的能力。要成功地实施本科生导师制 ,必须进一步完善学分制 ,大力提高教师素质 ,加快高等教育信息化进程。 相似文献
278.
Effect of extrusion wheel angular velocity on continuous extrusion forming process of copper concave bus bar 总被引:2,自引:0,他引:2
The continuous extrusion forming process for producing large section copper concave bus bar under different extrusion wheel angular velocities was studied by three-dimensional finite element technology based on software DEFORM-3D. The rigid-viscoplastic constitutive equation was employed in the model. The numerical simulation results show that the deformation body flow velocity in the die orifice increases gradually with the increase of the extrusion wheel angular velocity. But slippage between the rod and extrusion wheel occurs when the extrusion wheel angular velocity is high. The effective stress near the die orifice enhances gradually with increasing extrusion wheel angular velocity. High stress is concentrated in adjacent regions of the flash gap. The effective strain gradient is greater near the abutment than that near the die orifice. The effective strain of the product increases gradually with increasing extrusion wheel angular velocity. In the deformation process, the deformation body temperature increases remarkably due to friction and deformation. So the cooling is necessary in the region of the die and tools. 相似文献
279.
圆锥形零件极限变形程度可用极限拉深系数[mzd]=[d2/D0]来表示。根据圆锥形零件与圆筒形零件的内在联系,经力学分析得出了便于实用的圆锥形零件极限拉深系数[mzd]的计算表达式,并由此给出了用[mzd]所表示的成形极限曲线和第一次拉深时的极限拉深系数。经实验验证表明所确定的成形极限是准确和可靠的。 相似文献
280.
对非晶态Ni-B镀层的组织结构和性能进行研究,结果表明:非晶态Ni-B镀层以层片状沉积,表面具有胞状结构。经300°×1h热处理,镀层已经晶化,并析出了细小的Ni_3B相;提高加热温度,Ni_3B粒子明显长大。非晶态Ni-B镀层的镀态硬度为HV_(0.1)632,热处理对其硬度和耐磨性有明显的影响,二者分别在经300℃×1h和500℃×1h热处理后达到峰值。 相似文献