全文获取类型
收费全文 | 224181篇 |
免费 | 21275篇 |
国内免费 | 11559篇 |
专业分类
电工技术 | 15896篇 |
技术理论 | 14篇 |
综合类 | 15268篇 |
化学工业 | 35708篇 |
金属工艺 | 12444篇 |
机械仪表 | 14193篇 |
建筑科学 | 17458篇 |
矿业工程 | 7030篇 |
能源动力 | 6611篇 |
轻工业 | 15846篇 |
水利工程 | 4517篇 |
石油天然气 | 12810篇 |
武器工业 | 2031篇 |
无线电 | 27133篇 |
一般工业技术 | 26282篇 |
冶金工业 | 10395篇 |
原子能技术 | 2359篇 |
自动化技术 | 31020篇 |
出版年
2024年 | 1249篇 |
2023年 | 4561篇 |
2022年 | 8637篇 |
2021年 | 11659篇 |
2020年 | 8592篇 |
2019年 | 6680篇 |
2018年 | 7346篇 |
2017年 | 8211篇 |
2016年 | 7347篇 |
2015年 | 9850篇 |
2014年 | 12074篇 |
2013年 | 14283篇 |
2012年 | 15759篇 |
2011年 | 16473篇 |
2010年 | 14115篇 |
2009年 | 13299篇 |
2008年 | 12755篇 |
2007年 | 11680篇 |
2006年 | 11564篇 |
2005年 | 9987篇 |
2004年 | 6572篇 |
2003年 | 5441篇 |
2002年 | 4883篇 |
2001年 | 4354篇 |
2000年 | 4193篇 |
1999年 | 4709篇 |
1998年 | 3812篇 |
1997年 | 3248篇 |
1996年 | 3021篇 |
1995年 | 2442篇 |
1994年 | 1996篇 |
1993年 | 1412篇 |
1992年 | 1139篇 |
1991年 | 859篇 |
1990年 | 617篇 |
1989年 | 504篇 |
1988年 | 396篇 |
1987年 | 274篇 |
1986年 | 239篇 |
1985年 | 140篇 |
1984年 | 125篇 |
1983年 | 88篇 |
1982年 | 95篇 |
1981年 | 74篇 |
1980年 | 73篇 |
1979年 | 40篇 |
1978年 | 25篇 |
1977年 | 25篇 |
1976年 | 26篇 |
1951年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Changbin Shao Xiaoning Song Xibei Yang Xiaojun Wu 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2016,20(8):3177-3187
The changes of face images with poses and polarized illuminations increase data uncertainty in face recognition. In fact, synthesized mirror samples can be recognized as representations of the left–right deflection of poses or illuminations of the face. Symmetrical face images generated from the original face images also provide more observations of the face which is useful for improving the accuracy of face recognition. In this paper, to the best of our knowledge, it is the first time that the well-known minimum squared error classification (MSEC) algorithm is used to perform face recognition on an extended face database using synthesized mirror training samples, which is titled as extended minimum squared error classification (EMSEC). By modifying the MSE classification rule, we append the mirror samples to the training set for gaining better classification performance. First, we merge original training samples and mirror samples synthesized from original training samples per subject as mixed training samples. Second, EMSEC algorithm exploits mixed training samples to obtain the projection matrix that can best transform the mixed training samples into predefined class labels. Third, the projection matrix is exploited to simultaneously obtain transform results of the test sample and its nearest neighbor from the mixed training sample set. Finally, we ultimately classify the test sample by combining the transform results of the test sample and the nearest neighbor. As an extension of MSEC, EMSEC reduces the uncertainty of the face observation by auxiliary mirror samples, so that it has better robustness classification performance than traditional MSEC. Experimental results on the ORL, GT, and FERET databases show that EMSEC has better generalization ability than traditional MSEC. 相似文献
992.
993.
Kangshun Li Yunshan Wei Zhen Yang Wenhua Wei 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2016,20(3):885-893
With the development of modern image processing techniques, the numbers of images increase at a high speed in network. As a new form of visual communication, image is widely used in network transmission. However, the image information would be lost after transmission. In view of this, we are motivated to restore the image to make it complete in an effective and efficient way in order to save the network bandwidth. At present, there are two main methods for digital image restoration, texture-based method and non-textured-based method. In the texture-based method, Criminisi algorithm is a widely used algorithm. However, the inaccurate completion order and the inefficiency in searching matching patches are two main limitations of Criminisi algorithm. To overcome these shortcomings, in this paper, an exemplar image completion based on evolutionary algorithm is proposed. In the non-textured-based method, total variation method is a typical algorithm. An improved total variation algorithm is proposed in this paper. In the improved algorithm, the diffusion coefficients are defined according to the distance and direction between the damaged pixel and its neighborhood pixel. Experimental results show that the proposed algorithms have better general performance in image completion. And these two new algorithms could improve the experience of network surfing and reduce the network communication cost. 相似文献
994.
Simon Pedersen Petar Durdevic Kasper Stampe Sandra Lindberg Pedersen Zhenyu Yang 《国际自动化与计算杂志》2016,13(1):81-88
Severe slugging flow is always challenging in oil & gas production, especially for the current offshore based production. The slugging flow can cause a lot of problems, such as those relevant to production safety, fatigue as well as capability. As one typical phenomenon in multi-phase flow dynamics, the slug can be avoided or eliminated by proper facility design or control of operational conditions. Based on a testing facility which can emulate a pipeline-riser or a gas-lifted production well in a scaled-down manner, this paper experimentally studies the correlations of key operational parameters with severe slugging flows. These correlations are reflected through an obtained stable surface in the parameter space, which is a natural extension of the bifurcation plot. The maximal production opportunity without compromising the stability is also studied. Relevant studies have already showed that the capability, performance and efficiency of anti-slug control can be dramatically improved if these stable surfaces can be experimentally determined beforehand. The paper concludes that obtaining the stable surface on the new developed map can significantly improve the production rate in a control scheme. Even though the production rate can be further improved by moving the stable surface using advanced control strategies, the constant inputs can in some cases be preferable due to the easier implementation. 相似文献
995.
996.
Li-Xiang Ye Xiu Lin Xiang Chen Juan He Rong-Can Yang Hong-Yu Liu 《Quantum Information Processing》2016,15(7):2785-2796
A scheme is proposed to generate three-atom GHZ states by applying the inversely engineered control method on the basis of Lewis–Riesenfeld invariants. In the proposal, three atoms that have different configurations are trapped in a bimodal cavity. Numerical simulations indicate that our protocol has an obvious improvement of speed for the generation of GHZ states. Moreover, the present scheme is robust against both parameter fluctuations and dissipation. 相似文献
997.
Jun Yang Wen-Pin Luo Yong-Hu Wang Jun Cheng 《International Journal of Control, Automation and Systems》2016,14(2):367-377
This paper is concerned with improved stability criteria for uncertain T-S fuzzy systems with interval time-varying delay by means of a new (m,N)-delay-partitioning approach. Based on an appropriate augmented LKF established in the framework of state vector augmentation, some tighter bounding inequalities (Seuret-Wirtinger’s integral inequality, Peng-Park’s integral inequality and the reciprocally convex approach) have been employed to deal with (time-varying) delay-dependent integral items of the derivative of LKF, therefore, less conservative delaydependent stability criteria can be obtained on account of none of any useful time-varying items are arbitrarily ignored. It’s worth mentioning that, when the delay-partitioning number m is fixed, less conservatism can be achieved by increase of another delay-partitioning number N, but without increasing any computing burden. Finally, one numerical example is provided to show that the proposed conditions are less conservative than existing ones. 相似文献
998.
999.
1000.
针对城市给水管线不同管段在灾后对于管网整体可靠度影响的差异性,为了能够较好地评价不同管段对管网系统连接可靠度的贡献,引入失效概率重要度和关键重要度,建立了基于历史经验方法的管网可靠度及管线失效概率重要度、关键重要度计算模型。实例计算结果表明,该模型计算的管网连接可靠度结果与其他文献方法的计算结果基本一致,验证了模型的合理性、有效性。进而应用该模型计算出各段管线的失效概率重要度、关键重要度,对管线防灾等级划分,给出了管网分割方法与管网震后恢复策略。研究结果为编制给水管网抗震防灾规划、震后管网恢复计划及制定出相应的抗灾应急措施提供依据。 相似文献