全文获取类型
收费全文 | 21830篇 |
免费 | 1851篇 |
国内免费 | 989篇 |
专业分类
电工技术 | 1353篇 |
综合类 | 2454篇 |
化学工业 | 1860篇 |
金属工艺 | 2128篇 |
机械仪表 | 4163篇 |
建筑科学 | 2848篇 |
矿业工程 | 927篇 |
能源动力 | 396篇 |
轻工业 | 743篇 |
水利工程 | 604篇 |
石油天然气 | 713篇 |
武器工业 | 319篇 |
无线电 | 952篇 |
一般工业技术 | 2779篇 |
冶金工业 | 737篇 |
原子能技术 | 183篇 |
自动化技术 | 1511篇 |
出版年
2024年 | 73篇 |
2023年 | 230篇 |
2022年 | 438篇 |
2021年 | 573篇 |
2020年 | 611篇 |
2019年 | 544篇 |
2018年 | 510篇 |
2017年 | 728篇 |
2016年 | 806篇 |
2015年 | 881篇 |
2014年 | 1193篇 |
2013年 | 1273篇 |
2012年 | 1439篇 |
2011年 | 1625篇 |
2010年 | 1193篇 |
2009年 | 1253篇 |
2008年 | 1195篇 |
2007年 | 1538篇 |
2006年 | 1396篇 |
2005年 | 1151篇 |
2004年 | 968篇 |
2003年 | 875篇 |
2002年 | 699篇 |
2001年 | 602篇 |
2000年 | 552篇 |
1999年 | 495篇 |
1998年 | 308篇 |
1997年 | 351篇 |
1996年 | 274篇 |
1995年 | 229篇 |
1994年 | 159篇 |
1993年 | 111篇 |
1992年 | 86篇 |
1991年 | 66篇 |
1990年 | 55篇 |
1989年 | 58篇 |
1988年 | 54篇 |
1987年 | 24篇 |
1986年 | 11篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1959年 | 2篇 |
1958年 | 2篇 |
1957年 | 2篇 |
1956年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
溢流反弧段水流边界层有关概念的探讨 总被引:1,自引:1,他引:0
本文对溢流反孤段水流边界层的定义方法进行分析讨论。在分析及弧段流速分布的基础上提出离心力附加边界层厚度和粗糙度附加边界层厚度的概念,研究了壁面曲率和壁面粗糙度对溢流反弧段边界层发展的影响。 相似文献
72.
步行机攀登横杆的受力模型及分析 总被引:1,自引:1,他引:0
针对4足步行机器人的横杆攀登过程,在考虑弹性变形的基础上利用刚度矩阵建立其受力模型,并通过计算机仿真对攀登过程的不同情况进行了分析,其结果为具有攀登功能的步行机构结构设计及控制算法确定提供了理论依据。 相似文献
73.
Guo Dong Zhu Jing Xu Xue Jian Yan Jie Li Zhi Gang Zeng Miao Shen Li Zhang 《Thin solid films》2006,510(1-2):181-183
This paper introduces the Force Modulation technique to the study of crystallization process in ferroelectric vinylidene fluoride and trifluoroethylene copolymer films. Using this technique we have successfully visualized ferroelectric crystalline domains and observed that these ferroelectric domains grow out from amorphous phase, unite into strip-like structures, and finally congregate into a union. Force Modulation can weaken the influence of topography on imaging of ferroelectric domains, and reveal more details, which are difficult to be observed in topographical image. 相似文献
74.
75.
钢管机械扩径工艺研究 总被引:3,自引:0,他引:3
介绍了大口径直缝焊管机械扩径的优点,原理及扩径力的计算,找出影响扩径力及扩径头寿命的因素。 相似文献
76.
Human can handle a deformable object and damp its vibration with recognized skill. However, for an industrial robot, handling a deformable object with acute vibration is often a difficult task. This paper addresses the problem of active damping skill for handling deformable linear objects (DLOs) by using a strategy inspired from human manipulation skills. The strategy is illustrated by several rules, which are explained by a fuzzy and a P controller. A proportional-integral-derivative (PID) controller is also employed to explain the rules as a comparison. The interpretations from controllers are translated into high level commands in a robotic language V+. A standard industrial robot with a force/torque sensor mounted on the wrist was employed to demonstrate the skill. Experimental results showed the fuzzy based damping skill is quite effective and stable even without any previous acknowledge of the deformable linear objects.Category (5) 相似文献
77.
78.
A new curvature technique calculation for surface tension contribution in PLIC-VOF method 总被引:1,自引:0,他引:1
The volume of fluid (VOF) methods have been used for numerous numerical simulations. Among these techniques used to define
the moving interface, the piecewise linear interface reconstruction (PLIC-VOF) is one of the most accurate. A study of the
superficial tension impact on two-phase flow with free surface is presented. A new method based on direct staggered grid is
developped to include surface tension in PLIC-VOF. The new numerical curvature calculation method doesn't need smoothed colour
function and leads to less “spurious current”. This technique is applied to the calculus of surface tension force in the case
of the rise of air bubble in viscous liquid and the fall of liquid drop in the same liquid on free surface. Droplets, thin
layer and capillarity waves are observed after the free surface rupture for different Bond number. The influence of surface
tension calculus is then obvioused and when the drop hit the free surface, wavelets propagate toward the virtual boundaries
imposed. 相似文献
79.
A monolayer and a few layers of carbon sp2-bonded networks were torn and folded by the tip of an atomic force microscope at the steps on newly cleaved highly oriented pyrolytic graphite. It was found that the preferential breaking directions and folding axes are along the symmetry directions of the graphite hexagonal structure. Depending on the force exerted by the tip, breaking may occur along other directions. The torn part of the graphene sheet can even be stretched and deformed, and does not resume its original shape after release from the tip. 相似文献
80.
吴芳敏 《安徽冶金科技职业学院学报》2003,13(3):67-69
从企业营销工作实践和激励理论相结合的角度,论述了企业如何设计营销的激励和约束机制,提高销售人员的工作效率和积极性. 相似文献