全文获取类型
收费全文 | 11186篇 |
免费 | 980篇 |
国内免费 | 447篇 |
专业分类
电工技术 | 518篇 |
综合类 | 669篇 |
化学工业 | 1941篇 |
金属工艺 | 573篇 |
机械仪表 | 785篇 |
建筑科学 | 886篇 |
矿业工程 | 300篇 |
能源动力 | 339篇 |
轻工业 | 1044篇 |
水利工程 | 217篇 |
石油天然气 | 395篇 |
武器工业 | 53篇 |
无线电 | 1309篇 |
一般工业技术 | 1377篇 |
冶金工业 | 587篇 |
原子能技术 | 176篇 |
自动化技术 | 1444篇 |
出版年
2024年 | 46篇 |
2023年 | 197篇 |
2022年 | 403篇 |
2021年 | 467篇 |
2020年 | 378篇 |
2019年 | 283篇 |
2018年 | 346篇 |
2017年 | 379篇 |
2016年 | 371篇 |
2015年 | 479篇 |
2014年 | 626篇 |
2013年 | 741篇 |
2012年 | 748篇 |
2011年 | 802篇 |
2010年 | 650篇 |
2009年 | 705篇 |
2008年 | 628篇 |
2007年 | 563篇 |
2006年 | 589篇 |
2005年 | 463篇 |
2004年 | 312篇 |
2003年 | 307篇 |
2002年 | 331篇 |
2001年 | 255篇 |
2000年 | 225篇 |
1999年 | 229篇 |
1998年 | 203篇 |
1997年 | 127篇 |
1996年 | 149篇 |
1995年 | 107篇 |
1994年 | 87篇 |
1993年 | 66篇 |
1992年 | 56篇 |
1991年 | 52篇 |
1990年 | 41篇 |
1989年 | 32篇 |
1988年 | 22篇 |
1987年 | 17篇 |
1986年 | 14篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1981年 | 10篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1973年 | 4篇 |
1969年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
莫雁林 《计算机光盘软件与应用》2010,(12)
随着网络的不断发展,网络数据库安全日益凸显,目前网络数据库安全问题存在许多的威胁,本文就针对网络数据库安全策略提出了一些见解,而这些策略对网络数据库安全提供良好的保证. 相似文献
102.
We introduce a simple, linear time algorithm for recognizing trivially perfect (TP) graphs. It improves upon the algorithm of Yan et al. [J.-H. Yan, J.-J. Chen, G.J. Chang, Quasi-threshold graphs, Discrete Appl. Math. 69 (3) (1996) 247–255] in that it is certifying, producing a P4 or a C4 when the graph is not TP. In addition, our algorithm can be easily modified to recognize the complement of TP graphs (co-TP) in linear time as well. It is based on lexicographic BFS, and in particular the technique of partition refinement, which has been used in the recognition of many other graph classes [D.G. Corneil, Lexicographic breadth first search—a survey, in: WG 2004, in: Lecture Notes in Comput. Sci., vol. 3353, Springer, 2004, pp. 1–19]. 相似文献
103.
多工作模式产品配色意象的灰色评价方法 总被引:1,自引:0,他引:1
针对产品开发过程中的色彩规划问题,考虑多工作模式产品的配色特征,构建一种多工作模式产品的配色意象评价模型.基于灰色关联分析法建立产品方案色彩与意象之间的关联模型,运用灰色聚类法判断产品配色方案的意象值;将产品各工作模式下的配色意象同时作为评价属性并赋予相应的权值,进行综合评价.文中方法兼顾了多工作模式产品色彩面积的可变性和消费者主观意象的不确定性,将多工作模式产品的配色意象评价方法置于灵活、直观的框架中.最后以工程机械产品为应用实例,证明该方法较单属性评价方法更为贴近消费者的主观意象. 相似文献
104.
粒子群优化算法的发展趋势 总被引:3,自引:1,他引:2
分析优化算法的发展历程,指出粒子群优化算法(PSO)是基于群体智能的一种算法,简单易行,可调参数少,研究广泛且发展迅速.结合图形给出算法的个体极值和整体极值的搜优运动过程.研究总结算法的研究现状及特点,认为PSO还需要完善和继续研究.提出将算法应用于复杂的约束优化、随机优化与最优控制问题是算法应用研究的方向,并指出对该算法完整的收敛性分析是算法成熟的标志. 相似文献
105.
基于TMS320F2812的液晶显示模块接口设计 总被引:3,自引:0,他引:3
为适应工业应用现场以及智能化仪器仪表前端显示的需要,阐述了TMS320F2812DSP和QH2001液晶显示模块的原理及特性,提出了一种基于高速DSP处理器控制低速液晶显示模块的接口设计方案,并对该方案的硬件接口电路和软件驱动程序进行了设计,同时给出了软、硬件实现的相应电路图、程序流程图以及具体程序段;实验调试表明,设计方案结构简单、成本低、抗干扰能力强、显示性能稳定可靠,达到设计要求,能够有效解决高速DSP对低速LCD的驱动及显示问题,并取得了良好的显示效果,对其它便携式系统显示终端的设计也具有一定参考价值。 相似文献
106.
地下管线被视为城市的生命线。分析了地下管线定位仪的基本原理,并在此基础上详细介绍了基于ATmega 128单片机的数字化地下管线定位仪的硬件实现和软件实现,重点分析了基于磁保持继电器的分时供电电源电路。ATmega 128单片机实现了地下管线定位仪的数字化,使得定位仪能快速、准确地对地下管线进行水平定位和垂直定深。 相似文献
107.
Woon Jeung Park Rhee Man Kil 《Neural Networks, IEEE Transactions on》2009,20(10):1659-1673
The output of a classifier is usually determined by the value of a discriminant function and a decision is made based on this output which does not necessarily represent the posterior probability for the soft decision of classification. In this context, it is desirable that the output of a classifier be calibrated in such a way to give the meaning of the posterior probability of class membership. This paper presents a new method of postprocessing for the probabilistic scaling of classifier's output. For this purpose, the output of a classifier is analyzed and the distribution of the output is described by the beta distribution parameters. For more accurate approximation of class output distribution, the beta distribution parameters as well as the kernel parameters describing the discriminant function are adjusted in such a way to improve the uniformity of beta cumulative distribution function (CDF) values for the given class output samples. As a result, the classifier with the proposed scaling method referred to as the class probability output network (CPON) can provide accurate posterior probabilities for the soft decision of classification. To show the effectiveness of the proposed method, the simulation for pattern classification using the support vector machine (SVM) classifiers is performed for the University of California at Irvine (UCI) data sets. The simulation results using the SVM classifiers with the proposed CPON demonstrated a statistically meaningful performance improvement over the SVM and SVM-related classifiers, and also other probabilistic scaling methods. 相似文献
108.
Jae Kyeong Jeong Jong Han Jeong Hui Won Yang Tae Kyung Ahn Minkyu Kim Kwang Suk Kim Bon Seog Gu Hyun‐Joong Chung Jin‐Seong Park Yeon‐Gon Mo Hye Dong Kim Ho Kyoon Chung 《Journal of the Society for Information Display》2009,17(2):95-100
Abstract— A full‐color 12.1‐in.WXGA active‐matrix organic‐light‐emitting‐diode (AMOLED) display was, for the first time, demonstrated using indium‐gallium‐zinc oxide (IGZO) thin‐film transistors (TFTs) as an active‐matrix backplane. It was found that the fabricated AMOLED display did not suffer from the well‐known pixel non‐uniformity in luminance, even though the simple structure consisting of two transistors and one capacitor was adopted as the unit pixel circuit, which was attributed to the amorphous nature of IGZO semiconductors. The n‐channel a‐IGZO TFTs exhibited a field‐effect mobility of 17 cm2/V‐sec, threshold voltage of 1.1 V, on/off ratio >109, and subthreshold gate swing of 0.28 V/dec. The AMOLED display with a‐IGZO TFT array is promising for large‐sized applications such as notebook PCs and HDTVs because the a‐IGZO semiconductor can be deposited on large glass substrates (larger than Gen 7) using the conventional sputtering system. 相似文献
109.
The maximum entropy principle (MEP) is used to generate a natural probability distribution among the many possible that have
the same moment conditions. The MEP can accommodate higher order moment information and therefore facilitate a higher quality
PDF model. The performance of the MEP for PDF estimation is studied by using more than four moments. For the case with four
moments, the results are compared with those by the Pearson system. It is observed that as accommodating higher order moment,
the estimated PDF converges to the original one. A sensitivity analysis formulation of the failure probability based on the
MEP is derived for reliability-based design optimization (RBDO) and the accuracy is compared with that by finite difference
method (FDM). Two RBDO examples including a realistic three-dimensional wing design are solved by using the derived sensitivity
formula and the MEP-based moment method. The results are compared with other methods such as TR-SQP, FAMM + Pearson system,
FFMM + Pearson system in terms of accuracy and efficiency. It is also shown that an improvement in the accuracy by including
more moment terms can increase numerical efficiency of optimization for the three-dimensional wing design. The moment method
equipped with the MEP is found flexible and well adoptable for reliability analysis and design. 相似文献
110.