全文获取类型
收费全文 | 365篇 |
免费 | 9篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 10篇 |
综合类 | 25篇 |
化学工业 | 78篇 |
金属工艺 | 23篇 |
机械仪表 | 33篇 |
建筑科学 | 50篇 |
矿业工程 | 4篇 |
能源动力 | 12篇 |
轻工业 | 21篇 |
石油天然气 | 10篇 |
无线电 | 31篇 |
一般工业技术 | 49篇 |
冶金工业 | 7篇 |
原子能技术 | 2篇 |
自动化技术 | 30篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 24篇 |
2012年 | 18篇 |
2011年 | 22篇 |
2010年 | 21篇 |
2009年 | 13篇 |
2008年 | 22篇 |
2007年 | 28篇 |
2006年 | 25篇 |
2005年 | 34篇 |
2004年 | 15篇 |
2003年 | 17篇 |
2002年 | 12篇 |
2001年 | 9篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有385条查询结果,搜索用时 15 毫秒
291.
292.
Fu Hongliang Feng Guangzeng 《电子科学学刊(英文版)》2006,23(2):161-164
Two blind multiuser detection algorithms for antenna array in Code Division Multiple Access (CDMA) system which apply the linearly constrained condition to the Least Squares Constant Modulus Algorithln (LSCMA) are proposed in this paper. One is the Linearly Constrained LSCMA (LC-LSCMA), the other is the Preprocessing LC-LSCMA (PLC-LSCMA). The two algorithms are compared with the conventional LSCMA. The results show that the two algorithms proposed in this paper are superior to the conventional LSCMA and the best one is PLC-LSCMA. 相似文献
293.
Shi Kun Zhang Xudong 《电子科学学刊(英文版)》2006,23(2):181-183
This paper investigates adaptive blind source separation and equalization for Multiple Input Multiple Output (MIMO) systems. To effectively recover input signals, remove Inter-Symbol Interference (ISI) and suppress Inter-User Interference (IUI), the array input is first transformed into the signal subspace, then with the derived orthogonality between weight vectors of different input signals, a new orthogonal Constant Modulus Algorithm (CMA) is proposed. Computer simulation results illustrate the promising performance of the proposed method. Without channel identification, the proposed method can recover all the system inputs simultaneously and can be adaptive to channel changes without prior knowledge about signals. 相似文献
294.
Fu Hongliang Feng Guangzeng 《电子科学学刊(英文版)》2006,23(4):501-505
A novel Least Squares Constant Modulus (LSCM) beam-forming algorithm in smart antenna Multi-Carrier Code Division Multiple Access (MC-CDMA) system is proposed in this paper. It adaptively beam-forms the multi-carrier antenna array signal using the LSCM Algorithm (LSCMA), and in the meantime, the beam-formed signals on every sub-carrier are combined by using Orthogonal Restore Combination (ORC), Equal Gain Combination (EGC) or Maximum Ratio Combination (MRC). Then the decision of the combined signals and the spread-code of the expected user are used to re-construct the signals on every sub-carrier. At last, the difference between the re-constructed signal and the output signal of the beam-former is used to control the coefficients of the beam-former. The bit error probability of the proposed algorithm is analyzed. We simulated and compared it with the conventional LSCM beam-forming algorithm. Simulation results show that the proposed algorithm is superior to the latter in Bit Error Rate (BER). 相似文献
295.
Q345钢中厚板热矫直变形抗力与弹性模量数学模型的研究 总被引:1,自引:0,他引:1
根据中厚板矫直力的理论公式和Q345钢22~40mm板500~630℃矫直的生产实测数据,以变形抗力和弹性模量数学模型中的待定系数为优化变量,以矫直力计算误差最小为目标函数,采用单纯形法对待定系数进行优化计算,建立了Q345钢中厚板矫直过程变形抗力和弹性模量数学模型,得出Q345钢中厚板在500~630℃矫直过程随温度(T)提高,变形抗力(σs)降低:σs=-1080.1+4.8547 T-0.0048115 T~2;随温度(T)提高,弹性模量(E)先增加后减少:E= (-6.4807×10~5) +2576.5 T-2.3875 T~2。结果表明,矫直力的计算值和测量值的相对误差小于5%。 相似文献
296.
The compression and compaction behaviour of bentonite, limestone and microcrystalline cellulose (MCC) — three cohesive powders widely used in industry were studied. Uniaxial compression was performed in a cylindrical die, 40 mm in diameter and 70 mm high, for three selected cohesive powder samples. The initial density, instantaneous density and tablet density were determined. The influence of maximum pressure and deformation rate was examined. The secant modulus of elasticity Esec was calculated as a function of deformation rate v, maximum pressure p and powder sample. After compaction experiments in hydraulic press at three pressures - p = 30, 45 and 60 MPa - and two different deformation rates, the strength of the produced tablets was examined in a material strength testing machine.From uniaxial compression tests performed on the universal testing machine for loading and unloading, the modulus of elasticity E was calculated on the basis of the first linear phase of unloading. The total elastic recovery of tablets was also obtained. 相似文献
297.
HAN Guangping LIU Kai WANG Xiuhong 《机械工程学报(英文版)》2006,19(2):290-293
Six kinds of micro bridge-beam specimens with different sizes are fabricated using photolithography technology for bending test. Beam specimens with trapezoidal section could be representatives of those with rectangle and square section, which are usually applied in MEMS. Nano indentation method used in bending test can be applied to both elastic and plastic materials. Also, some mechanical properties parameters such as the modulus of elasticity, hardness and the bending strength are obtained. The average modulus of elasticity of SCS is 170.295 0±2.485 0 GPa, showing no size effects, but the bending strength ranges from 3.24 GPa to 10.15 GPa, displaying strong size effects, and the average hardness is 9.496 7±1.753 3 GPa, in which no obvious size effects are observed. 相似文献
298.
该文提出一种基于预处理递归最小二乘恒模算法(PP-RLSCMA)的多径异步CDMA系统盲自适应接收技术。首先对接收信号进行自适应预处理,并分析了预处理器的复杂性和稳定性。预处理的目的是通过对干扰和噪声的部分抑制以提高恒模接收的性能,所提出的预处理方法只与多径信道的最大长度有关。鉴于统计恒模算法收敛速度慢的缺点,提出一种快速递归最小二乘恒模算法的盲自适应接收。仿真表明,该文算法的误码率及收敛性能比LCMMV,LCCMA好。 相似文献
299.
试验研究了不同机制砂取代率对PK-3型板用混凝土工作性、抗压强度、劈裂抗拉强度和弹性模量的影响,并对实测弹性模量进行了拟合分析.结果 表明:机制砂部分或全取代河砂,改善了混凝土的工作性,提高了混凝土抗压强度、劈裂抗拉强度和弹性模量;通过回归分析拟合出的弹性模量函数表达式与实测数据拟合度较好;采用机制砂混凝土生产的PK-... 相似文献
300.