全文获取类型
收费全文 | 24093篇 |
免费 | 2935篇 |
国内免费 | 1263篇 |
专业分类
电工技术 | 3596篇 |
技术理论 | 1篇 |
综合类 | 2650篇 |
化学工业 | 567篇 |
金属工艺 | 568篇 |
机械仪表 | 2103篇 |
建筑科学 | 234篇 |
矿业工程 | 447篇 |
能源动力 | 231篇 |
轻工业 | 277篇 |
水利工程 | 115篇 |
石油天然气 | 600篇 |
武器工业 | 606篇 |
无线电 | 8640篇 |
一般工业技术 | 1583篇 |
冶金工业 | 401篇 |
原子能技术 | 205篇 |
自动化技术 | 5467篇 |
出版年
2024年 | 117篇 |
2023年 | 306篇 |
2022年 | 536篇 |
2021年 | 596篇 |
2020年 | 667篇 |
2019年 | 486篇 |
2018年 | 508篇 |
2017年 | 784篇 |
2016年 | 869篇 |
2015年 | 1097篇 |
2014年 | 1566篇 |
2013年 | 1390篇 |
2012年 | 1950篇 |
2011年 | 1992篇 |
2010年 | 1514篇 |
2009年 | 1405篇 |
2008年 | 1534篇 |
2007年 | 1982篇 |
2006年 | 1666篇 |
2005年 | 1434篇 |
2004年 | 1119篇 |
2003年 | 900篇 |
2002年 | 701篇 |
2001年 | 634篇 |
2000年 | 508篇 |
1999年 | 413篇 |
1998年 | 303篇 |
1997年 | 281篇 |
1996年 | 198篇 |
1995年 | 163篇 |
1994年 | 145篇 |
1993年 | 136篇 |
1992年 | 81篇 |
1991年 | 61篇 |
1990年 | 49篇 |
1989年 | 41篇 |
1988年 | 35篇 |
1987年 | 19篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 8篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1963年 | 4篇 |
1962年 | 2篇 |
1959年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Javier Ramírez Antonio García Uwe Meyer-Bäse Fred Taylor Antonio Lloris 《The Journal of VLSI Signal Processing》2003,33(1-2):171-190
Currently there are design barriers inhibiting the implementation of high-precision digital signal processing (DSP) objects with field programmable logic (FPL) devices. This paper explores overcoming these barriers by fusing together the popular distributed arithmetic (DA) method with the residue number system (RNS) for use in FPL-centric designs. The new design paradigm is studied in the context of a high-performance filter bank and a discrete wavelet transform (DWT). The proposed design paradigm is facilitated by a new RNS accumulator structure based on a carry save adder (CSA). The reported methodology also introduces a polyphase filter structure that results in a reduced look-up table (LUT) budget. The 2C-DA and RNS-DA are compared, in the context of a FPL implementation strategy, using a discrete wavelet transform (DWT) filter bank as a common design theme. The results show that the RNS-DA, compared to a traditional 2C-DA design, enjoys a performance advantage that increases with precision (wordlength). 相似文献
3.
基于直升机目标旋转部件的调制模型,本文针对防空雷达提出了分析直升机信号特征的一种新方法——WVD法,并对直升机目标旋转部件调制回波信号在不同噪声情况下加以仿真分析,结果表明:用WVD分析雷达回波中直升机信号特征是一种非常有效的方法。 相似文献
4.
Ying Tan 《The Journal of VLSI Signal Processing》2002,32(1-2):45-54
In this paper, we propose a new approach for signal detection in wireless digital communications based on the neural network with transient chaos and time-varying gain (NNTCTG), and give a concrete model of the signal detector after appropriate transformations and mappings. It is well known that the problem of the maximum likelihood signal detection can be described as a complex optimization problem that has so many local optima that conventional Hopfield-type neural networks fail to solve. By refraining from the serious local optima problem of Hopfield-type neural networks, the NNTCTG makes use of the time-varying parameters of the recurrent neural network to control the evolving behavior of the network so that the network undergoes the transition from chaotic behavior to gradient convergence. It has richer and more flexible dynamics rather than conventional neural networks only with point attractors, so that it can be expected to have much ability to search for globally optimal or near-optimal solutions. After going through a transiently inverse-bifurcation process, the NNTCTG can approach the global optimum or the neighborhood of global optimum of our problem. Simulation experiments have been performed to show the effectiveness and validation of the proposed neural network based method for the signal detection in digital communications. 相似文献
5.
6.
二次型时频分析技术的开发与应用 总被引:1,自引:1,他引:0
基于二次型的时频分析是高分辨率时频分析技术的有效方法之一,该项技术能够有效反映时变信号的频谱特性,具有分辨率高、能量集中和跟踪瞬时频率的特点。从时变信号的特点出发,阐述了二次型时频分析技术的基本方法原理,采用正演模型分析验证了该方法的有效性,并在实际地震资料中应用于识别物源方向、划分沉积相带、预测储层结构以及相对厚度等诸多方面,均取得了较好的效果。 相似文献
7.
杨之纬 《网络安全技术与应用》2014,(10):83-83
本文主要研究CDMA系统对GSM系统的上行干扰,通过实验以及理论计算分析CDMA干扰对GSM系统的影响,并结合天线隔离度分析两系统之间的安全距离. 相似文献
8.
混合交通下右转机动车信号配时方法 总被引:1,自引:0,他引:1
为了减少右转机动车与直行自行车之间的干扰,提高交叉口的运行效率,本文分析了两相位信号控制交叉口右转机动车与自行车之间的冲突规律以及自行车交通流的行驶特性,确定设置右转机动车信号的直行自行车流量临界值.以减少冲突和提高交叉口运行效率为目标,确定右转机动车相位绿灯起亮时刻和绿灯时长,并建立了相应的参数标定模型.以实际调查数据为基础,应用VISSIM模拟软件进行模拟验证,结果表明,设置右转机动车信号后,右转机动车延误和机非冲突明显减少. 相似文献
9.
To explore the effect of puerarin on insulin receptor (IR), insulin receptor substrate-1 (IRS-1) and protein expression of protein kinase B(PKB) in the P13K pathway of the glucose consumption, transportation and insulin signal transduction in 3T3-L1 adipocytes with insulin resistance. The insulin resistance 3T3-L1 adipocytes model was established by free fatty acid induction. The model cells were managed with puerarin in different concentrations. Glucose consumption was detected with glucose oxidase method, glucose transportation rate was determined by 2-deoxy-3H glucose ingesting method, and the IR, IRS-1 and PKB expression were determined by Western blot. Glucose consumption and transportation were significantly decreased in the model adipocytes, but increased after treated with puerarin (P<0.01). Moreover, the level of tyrosine phosphorylation of IR subunit β was higher in the puerarin treated groups, and that of IRS-1 was higher in the group treated with low dose puerarin than that in the model group. The 3T3-L1 adipocytes of insulin resistance model could be induced by free fatty acid successfully, puerarin could promote the glucose utilization in them to alleviate the insulin resistance, which may be related with the action in advancing the tyrosine phosphorylation of IR and IRS-1. 相似文献
10.