全文获取类型
收费全文 | 9139篇 |
免费 | 1510篇 |
国内免费 | 1212篇 |
专业分类
电工技术 | 829篇 |
综合类 | 929篇 |
化学工业 | 211篇 |
金属工艺 | 159篇 |
机械仪表 | 607篇 |
建筑科学 | 106篇 |
矿业工程 | 137篇 |
能源动力 | 58篇 |
轻工业 | 89篇 |
水利工程 | 68篇 |
石油天然气 | 334篇 |
武器工业 | 213篇 |
无线电 | 2277篇 |
一般工业技术 | 492篇 |
冶金工业 | 124篇 |
原子能技术 | 34篇 |
自动化技术 | 5194篇 |
出版年
2024年 | 60篇 |
2023年 | 141篇 |
2022年 | 252篇 |
2021年 | 355篇 |
2020年 | 424篇 |
2019年 | 336篇 |
2018年 | 341篇 |
2017年 | 416篇 |
2016年 | 456篇 |
2015年 | 529篇 |
2014年 | 701篇 |
2013年 | 629篇 |
2012年 | 770篇 |
2011年 | 802篇 |
2010年 | 605篇 |
2009年 | 597篇 |
2008年 | 639篇 |
2007年 | 706篇 |
2006年 | 571篇 |
2005年 | 417篇 |
2004年 | 338篇 |
2003年 | 307篇 |
2002年 | 233篇 |
2001年 | 222篇 |
2000年 | 149篇 |
1999年 | 124篇 |
1998年 | 127篇 |
1997年 | 114篇 |
1996年 | 97篇 |
1995年 | 58篇 |
1994年 | 58篇 |
1993年 | 58篇 |
1992年 | 38篇 |
1991年 | 27篇 |
1990年 | 18篇 |
1989年 | 19篇 |
1988年 | 10篇 |
1987年 | 4篇 |
1986年 | 16篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1975年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Massive Open Online Courses (MOOCs) are becoming an essential source of information for both students and teachers. Noticeably, MOOCs have to adapt to the fast development of new technologies; they also have to satisfy the current generation of online students. The current MOOCs’ Management Systems, such as Coursera, Udacity, edX, etc., use content management platforms where content are organized in a hierarchical structure. We envision a new generation of MOOCs that support interpretability with formal semantics by using the SemanticWeb and the online social networks. Semantic technologies support more flexible information management than that offered by the current MOOCs’ platforms. Annotated information about courses, video lectures, assignments, students, teachers, etc., can be composed from heterogeneous sources, including contributions from the communities in the forum space. These annotations, combined with legacy data, build foundations for more efficient information discovery in MOOCs’ platforms. In this article we review various Collaborative Semantic Filtering technologies for building Semantic MOOCs’ management system, then, we present a prototype of a semantic middle-sized platform implemented at Western Kentucky University that answers these aforementioned requirements. 相似文献
3.
Innumerable casualties due to intrauterine hypoxia are a major worry during prenatal phase besides advanced patient monitoring with latest science and technology. Hence, the analysis of foetal electrocardiogram (fECG) signals is very vital in order to evaluate the foetal heart status for timely recognition of cardiac abnormalities. Regrettably, the latest technology in the cutting edge field of biomedical signal processing does not seem to yield the desired quality of fECG signals required by physicians, which is the major cause for the pathetic condition. The focus of this work is to extort non-invasive fECG signal with highest possible quality with a motive to support physicians in utilizing the methodology for the latest intrapartum monitoring technique called STAN (ST analysis) for forecasting intrapartum foetal hypoxia. However, the critical quandary is that the non-invasive fECG signals recorded from the maternal abdomen are affected by several interferences like power line interference, baseline drift interference, electrode motion interference, muscle movement interference and the maternal electrocardiogram (mECG) being the dominant interference. A novel hybrid methodology called BANFIS (Bayesian adaptive neuro fuzzy inference system) is proposed. The BANFIS includes a Bayesian filter and an adaptive neuro fuzzy filter for mECG elimination and non-linear artefacts removal to yield high quality fECG signal. Kalman filtering frame work has been utilized to estimate the nonlinear transformed mECG component in the abdominal electrocardiogram (aECG). The adaptive neuro fuzzy filter is employed to discover the nonlinearity of the nonlinear transformed version of mECG and to align the estimated mECG signal with the maternal component in the aECG signal for annulment. The outcomes of the investigation by the proposed BANFIS system proved valuable for STAN system for efficient prediction of foetal hypoxia. 相似文献
4.
提出一种适用于DS-CDMA无线通信系统的低计算量而性能良好的信道估计算法。在DS-CDMA系统中,当接收信号经过解扩或多用户检测等时域预处理后,可以认为干扰大大减弱、期望信号在处理后的信号中占主要地位。这样,用预处理后信号相关阵的最大特征值对应的特征矢量可以很好地近似期望信号的信道矢量。但是,直接特征分解需要很大的计算量,特征跟踪计算量较低,但瞬态性能较差。本文提出一种基于相关矩阵列矢量平均的信道估计算法,该算法不需要特征分解或跟踪。仿真结果表明:新算法在降低计算量的情况下可以获得同直接特征分解方法几乎相同的性能。 相似文献
5.
6.
Multi-valued and universal binary neurons (MVN and UBN) are the neural processing elements with the complex-valued weights and high functionality. It is possible to implement an arbitrary mapping described by partially defined multiple-valued function on the single MVN. An arbitrary mapping described by partially defined or fully defined Boolean function, which can be non-threshold, may be implemented on the single UBN. The quickly converging learning algorithms exist for both types of neurons. Such features of the MVN and UBN may be used for solving the different problems. One of the most successful applications of the MVN and UBN is their usage as basic neurons in the Cellular Neural Networks (CNN). It opens the new effective opportunities in nonlinear image filtering and its applications to noise reduction, edge detection and solving of the super resolution problem. A number of experimental results are presented to illustrate the performance of the proposed algorithms.An erratum to this article can be found at 相似文献
7.
M. D. Beard M. J. S. Lowe 《International Journal of Rock Mechanics and Mining Sciences》2003,40(4):527-536
The research outlined in this paper is aimed at the development of a portable non-destructive testing instrument for evaluating the condition of rock bolts. In applications such as coal mine roof reinforcement, the opportunities for rock bolt inspection are currently limited to destructive techniques such as the pull-out test. It is proposed that guided ultrasonic waves can be used to solve this inspection problem, using a pulse-echo test carried out from the free end of the bolt. Suitable test frequencies have been identified through the use of modelling software, and successful laboratory and site trials have been undertaken. The research has shown that the proposed approach is capable of determining the bolt length, and of identifying major defects such as necking, deformation, and loss of resin encapsulation. 相似文献
8.
本文提出了一种直接把红外前视传感器的输出作为测量值来跟踪红外目标的扩展型卡尔曼滤波跟踪算法。在滤波处理时,设置可变的测量矩阵,其目的在于提高运算速度和抑制噪声干扰。通过具体的实例,对所提跟踪算法的特点和有效性进行了细致的分析。 相似文献
9.
太钢4号高炉喷煤站从1990年起采用MFD-Ⅲ型脉动反吹式布袋除尘器。这种除尘器采用脉动式反吹清灰设施,合理布置布袋间距,布袋支撑骨架及选用针呢材质的布袋,过滤面积大,反吹清灰效果好,设备运行平稳,除尘效率高达99.8%,排放浓度小于10mg/m^3,故障率低。 相似文献
10.
探讨了过滤器孔径对6063铝合金铸锭组织和性能的影响规律。在此基础上指出,在过滤工艺恰当时,不仅可以减少铸锭中的夹杂物,而且可以有效地防止裂纹、羽毛晶等连续铸锭中的常见缺陷。 相似文献