全文获取类型
收费全文 | 2037篇 |
免费 | 142篇 |
国内免费 | 80篇 |
专业分类
电工技术 | 134篇 |
综合类 | 269篇 |
化学工业 | 56篇 |
金属工艺 | 76篇 |
机械仪表 | 312篇 |
建筑科学 | 62篇 |
矿业工程 | 24篇 |
能源动力 | 29篇 |
轻工业 | 22篇 |
水利工程 | 20篇 |
石油天然气 | 14篇 |
武器工业 | 33篇 |
无线电 | 283篇 |
一般工业技术 | 295篇 |
冶金工业 | 145篇 |
原子能技术 | 59篇 |
自动化技术 | 426篇 |
出版年
2024年 | 6篇 |
2023年 | 21篇 |
2022年 | 17篇 |
2021年 | 32篇 |
2020年 | 39篇 |
2019年 | 39篇 |
2018年 | 42篇 |
2017年 | 55篇 |
2016年 | 65篇 |
2015年 | 98篇 |
2014年 | 99篇 |
2013年 | 159篇 |
2012年 | 127篇 |
2011年 | 132篇 |
2010年 | 74篇 |
2009年 | 80篇 |
2008年 | 97篇 |
2007年 | 138篇 |
2006年 | 106篇 |
2005年 | 111篇 |
2004年 | 99篇 |
2003年 | 95篇 |
2002年 | 69篇 |
2001年 | 57篇 |
2000年 | 50篇 |
1999年 | 41篇 |
1998年 | 39篇 |
1997年 | 37篇 |
1996年 | 23篇 |
1995年 | 27篇 |
1994年 | 31篇 |
1993年 | 18篇 |
1992年 | 21篇 |
1991年 | 11篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 12篇 |
1987年 | 4篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1978年 | 3篇 |
1975年 | 3篇 |
1965年 | 6篇 |
1964年 | 3篇 |
1963年 | 3篇 |
1956年 | 3篇 |
排序方式: 共有2259条查询结果,搜索用时 0 毫秒
21.
以《中国大学生英汉汉英口笔译语料库》中的口语语料为数据来源,从2007年英语专八口语测试的汉译英部分,随机抽取100位考生的语料作为研究对象,分析考生口语输出中的错误,探究英语专业学生口语输出中言语错误的自我意识情况。 相似文献
22.
制造误差的灰自助动态预报 总被引:3,自引:0,他引:3
综合考虑灰色系统理论和Bootstrap统计理论的信息预报特点,建立制造误差的灰自助动态预报模型GBM(1,1),以解决信息预报中存在的一些问题。GBM(1,1) 在灰微分建模时进行Bootstrap再抽样,更多地挖掘系统信息,从而更准确地预报系统真值及其分布区间的瞬态变化状况。在计算机仿真中,研究了各种随机误差系统例如正态分布、瑞利分布、均匀分布、三角分布以及混合分布等系统的预报问题,也涉及到一些系统误差例如上升趋势、下降趋势和周期趋势等误差的预报问题。在实际试验中,研究了滚动轴承套圈磨削圆度误差的预报问题。计算机仿真和试验研究表明,GBM(1,1)允许小的数据样本以及各种类型的随机误差与系统误差存在,预报的准确率可以达到95%以上。 相似文献
23.
24.
在高度计绝对定标实验中,利用差分GPS(Differential GPS,DGPS)浮标进行现场海面高测量得到的海面高(Sea Surface Height,SSH)序列之中,除了包含有由风浪引起的高频噪声外,还包括了仪器误差造成的影响。前者可通过低通滤波方式消除,而后者由于是全频段的白噪声,不能通过低通滤波的方式消除。通过研究奇异谱分析(Singular Spectrum Analysis,SSA)的方法,确定了嵌入维数和截断长度的选取准则,并对其进行仿真,验证了该方法在消除海面高序列的仪器误差噪声中的有效性,同时也验证了嵌入维数和截断长度选取准则的有效性。最后,利用该方法处理了某次DGPS浮标实验获得的海面高序列,处理结果与原始序列相比较为平滑,且在精度上有一定的改善,验证了奇异谱分析方法的有效性。 相似文献
25.
26.
C语言是许多高校开设的第一门程序设计语言,使用方便灵活。根据C语言的特点,并结合实际教学,对在编程中经常遇到的错误进行分析、总结,为初学者尽快掌握C语言,提高程序设计水平提供借鉴。 相似文献
27.
Dharminder Dharminder Pradeep Kumar Dadsena Pratik Gupta Sathya Sankaran 《International Journal of Satellite Communications and Networking》2023,41(1):14-28
Satellite's communication system is used to communicate under significant distance and circumstances where the other communication systems are not comfortable. Since all the data are exchanged over a public channel, so the security of the data is an essential component for the communicating parties. Both key exchange and authentication are two cryptographic tools to establish a secure communication between two parties. Currently, various kinds of authentication protocols are available to establish a secure network, but all of them depend on number–theoretical (discrete logarithm problem/factorization assumption) hard assumptions. Due to Shor's and Grover's computing algorithm number theoretic assumptions are breakable by quantum computers. Although Kumar and Garg have proposed a quantum attack-resistant protocol for satellite communication, it cannot resist stolen smart card attack. We have analyzed that how Kumar and Garg is vulnerable to the stolen smart card attack using differential power analysis attack described in He et al and Chen and Chen. We have also analyzed the modified version of signal leakage attack and sometimes called improved signal leakage attack on Kumar and Garg's protocol. We have tried to construct a secure and efficient authentication protocol for satellites communication that is secure against quantum computing. This is more efficient as it requires only three messages of exchange. This paper includes security proof and performance of the proposed authentication and key agreement protocol. 相似文献
28.
29.
S. S. Kourehli 《Inverse Problems in Science & Engineering》2017,25(3):418-433
This paper presents novel approach to structural damage detection and estimation using incomplete static responses of a damaged structure and least squares support vector machine (LS-SVM). The presented method is based on the reduced stiffness matrix to formulate incomplete static responses as input parameters to the LS-SVM. The presented method is applied to a plane steel bridge, a four-span continuous beam and four-storey plane frame containing several damages. Also, the effect of the discrepancy in stiffness between the finite element model and the actual tested system has been investigated. The results show that the presented method is sensitive to the location and severity of the structural damage in spite of the incomplete noisy data and modelling errors. 相似文献
30.
H.S.J. Rashid C.S. Place G.R. Braithwaite 《International Journal of Industrial Ergonomics》2010,40(6):636-647
In this paper a statistical analysis of a sample of 58 helicopter maintenance-induced safety occurrences is conducted to study helicopter accidents and incidents’ survivability and the severity distribution of such occurrences. Analysis is also carried out to identify helicopter main and sub-systems mostly exposed to maintenance errors and to determine various types of such errors. Expected inherent relations between rotorcraft components affected and types of associated maintenance errors are investigated. Human factors-based triggers of these accidents and severe incidents are explored. The concept of Specific Failures (SFs) that immediately precede each of such occurrences is introduced for more detailed representation of the last breached individual and organizational safety barriers. Root causes of these safety occurrences were then sought utilizing the Human Factors Analysis and Classification System-Maintenance Extension (HFACS-ME) taxonomy with a refined focus on its third order categories’ list. The rotorcraft characteristics influencing individuals and organizational behaviours within Maintenance, Repair and Overhaul organizations (MROs) are discussed in the light of the root cause investigation results.