全文获取类型
收费全文 | 455篇 |
免费 | 66篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 21篇 |
综合类 | 45篇 |
化学工业 | 72篇 |
金属工艺 | 5篇 |
机械仪表 | 27篇 |
建筑科学 | 57篇 |
矿业工程 | 14篇 |
能源动力 | 58篇 |
轻工业 | 40篇 |
水利工程 | 9篇 |
石油天然气 | 14篇 |
武器工业 | 1篇 |
无线电 | 76篇 |
一般工业技术 | 35篇 |
冶金工业 | 8篇 |
原子能技术 | 4篇 |
自动化技术 | 53篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 22篇 |
2015年 | 10篇 |
2014年 | 22篇 |
2013年 | 28篇 |
2012年 | 34篇 |
2011年 | 36篇 |
2010年 | 25篇 |
2009年 | 29篇 |
2008年 | 24篇 |
2007年 | 34篇 |
2006年 | 18篇 |
2005年 | 26篇 |
2004年 | 18篇 |
2003年 | 35篇 |
2002年 | 20篇 |
2001年 | 15篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 16篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有539条查询结果,搜索用时 31 毫秒
21.
滚轧直螺纹钢筋连接技术的应用和实践 总被引:1,自引:1,他引:0
通过新疆石河子天盛(北区)织染工业园一期一区厂房工程滚轧直螺纹钢筋连接技术的应用,制订了一套完整的施工、质量控制方案,通过实践证明取得了良好的质量经济效果。 相似文献
22.
For decades, numerous artificial muscles have been proposed in order to implement beneficial features of biological muscles into robotics. Unfortunately, traditional artificial muscles experienced difficulties in imitating properties of the biological muscles due to mechanical and control issues. Recently, twisted and coiled polymer actuators (TCP) have been shown to produce large mechanical power via thermal stimulations and strong linearity. In this paper, a high-performance TCP thermally cycled by electrical heating and forced convective liquid cooling is designed and associated control algorithms are presented. We elaborate the model of the TCP that is simple, yet provides insight into how the electrical heating and the forced convective liquid cooling contribute to the TCP actuation. The proposed model is verified by experimental studies. Based on the proposed model, we design a feedforward–feedback controller and switching laws, which actively control the TCP in both the heating and cooling cycles. Furthermore, we extend our control methodology to agonist–antagonist TCPs. From the experimental studies, the proposed method is shown to be effective in both single TCP and antagonistic TCPs. 相似文献
23.
We used the method of moments (MoM), which is a numerical electromagnetic field computation method, to study the surge characteristics of twisted pair single‐phase electric power lines. The results show that wires stranded with less than several turns per meter have almost the same surge characteristics as parallel lines, but the surge impedance decreases in tens of % when the number of strands increases. To verify the simulation results, we measured the surge characteristics of a model line of twisted pair experimentally, and there is good accordance between them. It is possible to simulate the surge in twisted pair covered with polymer dielectric insulators by MoM. Moreover, we studied the surge characteristics of twisted pair which is inserted into a metal tube. According to the results, the effect of the strand is smaller than that in free space without the metal pipe. There are two propagation modes in common mode: fast surge and slow surge. Few influences of the number of strands on the surge velocity occur in the fast propagation surge, but the increase of the surge impedance and the slowdown of the propagation speed are caused by twining in the slow propagation mode. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(3): 1–9, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20737 相似文献
24.
A. F. Ryzhkov L. Zhargalkhuu Nadir Saman M. Sharif A. D. Makhaev 《Journal of Engineering Physics and Thermophysics》2009,82(1):21-28
To estimate the thermohydraulic efficiency of different types of swirlers of heat exchange in pipes, we have generalized the
experimental data, which has made it possible to determine the optimal range of Reynolds numbers and the optimal geometric
sizes of swirlers.
Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 23–30, January–February, 2009. 相似文献
25.
提出一种新型的正反两个方向交替扭转的扭带模型,并基于ANSYS FLUENT软件在层流状态下(Re=400~18 00)对换热管中插入新型扭带的换热特性、流体阻力特性和综合性能指标进行数值模拟研究。对y=3.0,4.5,6.0三种扭率下的无缺口正反扭转扭带与传统单一方向扭带进行对比研究,并对扭率y=3.0的无缺口正反扭转扭带和带有三角、半圆及方形缺口的正反扭转扭带进行了对比计算。研究结果表明:插入不同扭率的扭带,换热管的努赛尔数Nu、摩擦系数f与综合性能PEC值均随着扭率的减小而增大;相同扭率下无缺口的正反扭转扭带在强化换热效果和综合性能表现上要优于传统扭带;扭率为3.0时,无缺口的正反扭转扭带比带三种缺口的正反扭转扭带换热效果好,而缺口的存在可以大幅度地降低插入扭带产生的摩擦阻力,且缺口的面积越大,摩擦和换热效果降低越多。 相似文献
26.
为探究扭旋叶片的结构参数--扭率变化率Tv对管道换热的影响,以水为介质,在Tv=-5~5范围内,采用实验和数值模拟方法研究了恒壁温条件下流体的传热和阻力特性,并分析了综合传热性能及强化传热机理。结果表明,沿流动方向Tv>0的扭旋叶片安装方式强化传热效果优于Tv=0,研究范围内Tv=2.5时综合强化传热比最高,相对Tv=0平均提高5.0%。而Tv<0时强化传热效果劣于Tv=0,应避免此种叶片安装方式。扭率的变化影响了流场结构,当Tv>0时,在近1/2流动区域内绕流旋涡的涡量和影响区域明显增加,同时,在绕流旋涡流动区域,压力、速度和温度的三场协同程度得到提高,进而强化了换热管道的传热效果。 相似文献
27.
Jianxi FAN Shukui ZHANG Wujun ZHOU Baolei CHENG Kenli LI 《Frontiers of Computer Science》2010,4(4):489
The dimensions of twisted cubes are only limited to odd integers. In this paper, we first extend the dimensions of twisted cubes to all positive integers. Then, we introduce the concept of the restricted faulty set into twisted cubes. We further prove that under the condition that each node of the n-dimensional twisted cube TQn has at least one fault-free neighbor, its restricted connectivity is 2n − 2, which is almost twice as that of TQn under the condition of arbitrary faulty nodes, the same as that of the n-dimensional hypercube. Moreover, we provide an O(NlogN) fault-free unicast algorithm and simulations result of the expected length of the fault-free path obtained by our algorithm, where N denotes the node number of TQn. Finally, we propose a polynomial algorithm to check whether the faulty node set satisfies the condition that each node of the n-dimensional twisted cube TQn has at least one fault-free neighbor. 相似文献
28.
阐述了螺旋扭状增强材料的螺旋效应表现,分析了螺旋扭状增强材料几何形态特征参数,提出了螺旋扭状增强材料粘结锚固力的机理模型,并进行了基本公式推导和敏感性分析.结果表明,减小螺旋扭状增强材料的节距对于其荷载-滑移曲线的第一峰值影响不大,但可明显提高其荷载-滑移曲线第二峰值, 这与冷轧扭钢筋和螺旋扭状钢纤维拉拔实验结果相吻合.另外,从理论上证明了螺旋扭状增强材料的螺旋效应具有必然性. 相似文献
29.
30.
采用RNG k-ε数值模拟方法研究一种新型内插松弛扭带波节管(CLT)的流动与传热特性。将数值模拟结果与自建实验台的实验结果进行了对比验证;比较了CLT和内插松弛扭带光管(SLT)的传热性能差异;考察了CLT中扭率和余隙比对流动和传热特性的影响规律。研究结果表明CLT相比于传统的SLT,传热性能最多提高1.17倍,综合传热性能的绝对数值最多增加0.15。CLT的综合传热性能随着扭率的增加而增加,而增加的幅度却逐渐减小,高Reynolds数时减小的程度更加显著。同时,综合传热性能随着余隙比的增大而降低并且降低的幅度也逐渐减小,在低Reynolds数时明显降低,而在高Reynolds数时略微降低。综合考虑,低Reynolds数时应该选择余隙比低的扭带,而高Reynolds数时则应选择余隙比高的扭带。 相似文献