全文获取类型
收费全文 | 58511篇 |
免费 | 6420篇 |
国内免费 | 4122篇 |
专业分类
电工技术 | 4296篇 |
综合类 | 5571篇 |
化学工业 | 8662篇 |
金属工艺 | 3947篇 |
机械仪表 | 3627篇 |
建筑科学 | 4101篇 |
矿业工程 | 1949篇 |
能源动力 | 1439篇 |
轻工业 | 7701篇 |
水利工程 | 1706篇 |
石油天然气 | 1960篇 |
武器工业 | 748篇 |
无线电 | 5529篇 |
一般工业技术 | 5702篇 |
冶金工业 | 2270篇 |
原子能技术 | 819篇 |
自动化技术 | 9026篇 |
出版年
2024年 | 362篇 |
2023年 | 957篇 |
2022年 | 2373篇 |
2021年 | 2960篇 |
2020年 | 2208篇 |
2019年 | 1643篇 |
2018年 | 1762篇 |
2017年 | 1919篇 |
2016年 | 1758篇 |
2015年 | 2787篇 |
2014年 | 3492篇 |
2013年 | 4181篇 |
2012年 | 5013篇 |
2011年 | 5268篇 |
2010年 | 4781篇 |
2009年 | 4470篇 |
2008年 | 4453篇 |
2007年 | 4346篇 |
2006年 | 3640篇 |
2005年 | 2811篇 |
2004年 | 2025篇 |
2003年 | 1345篇 |
2002年 | 1207篇 |
2001年 | 1035篇 |
2000年 | 818篇 |
1999年 | 369篇 |
1998年 | 191篇 |
1997年 | 136篇 |
1996年 | 103篇 |
1995年 | 86篇 |
1994年 | 72篇 |
1993年 | 53篇 |
1992年 | 47篇 |
1991年 | 35篇 |
1990年 | 39篇 |
1989年 | 43篇 |
1988年 | 30篇 |
1987年 | 37篇 |
1986年 | 31篇 |
1985年 | 22篇 |
1984年 | 17篇 |
1983年 | 18篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 19篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1976年 | 12篇 |
1959年 | 12篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
41.
42.
Juan Wang 《International journal of systems science》2016,47(12):2935-2944
Robust stabilisation and L2-gain analysis for a class of switched systems with actuator saturation are studied in this paper. The switching signal of the controllers lags behind that of the system modes, which leads to the asynchronous switching between the candidate controllers and the subsystems. By combining the piecewise Lyapunov function method with the convex hull technique, sufficient conditions in terms of LMIs for the solvability of the robust stabilisation and weighted L2-gain problems are presented respectively under the dwell time scheme. Finally, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed results. 相似文献
43.
Juan C. Granda Pelayo Nuño Julio Molleda Rubén Usamentiaga Daniel F. García 《Multimedia Systems》2016,22(5):543-557
Real-time interactive multimedia communications are becoming increasingly useful for education, business, e-commerce and e-government, providing an enriched user experience in teleconferencing, e-meetings, distance training and product demonstrations. Large corporations are usually located at several sites, so real-time multipoint sessions within corporations are especially difficult. IP multicast is available or feasible within each site of an organization. Thus, corporate networks can be considered as various multicast-capable networks interconnected through a wide area network without multicast connectivity. This paper proposes a resilient self-managed overlay network to support real-time multipoint interactive sessions within corporate networks. The proposed overlay takes advantage of the configuration of corporate networks to self-organize and provide an efficient media delivery service, making use of multicast communications wherever available. Various self-healing techniques are implemented allowing for the continuity of ongoing sessions in spite of network disruptions and entity failures. Extensive simulations and tests have been carried out to assess the performance and resilience of the overlay facing several types of disruptions. 相似文献
44.
Deng Juan Zhao Shu Wang Yan Wang Lei Wang Hong Sha Hong 《Multimedia Tools and Applications》2017,76(7):10097-10117
Multimedia Tools and Applications - Most of the existing image encryption algorithms based on compressive sensing are too complex to operate. An image compression-encryption scheme with simple... 相似文献
45.
介绍一个基于Android平台的人机交互设计方案:通过编程将手机变为PC的无线控制器,可提供PPT遥控、无线游戏手柄、远程关机及锁屏等功能。 相似文献
46.
Juan Francisco Gómez-Lopera José Martínez-Aroza Aureliano M. Robles-Pérez Ramón Román-Roldán 《Journal of Mathematical Imaging and Vision》2000,13(1):35-56
This work constitutes a theoretical study of the edge-detection method by means of the Jensen-Shannon divergence, as proposed by the authors. The overall aim is to establish formally the suitability of the procedure of edge detection in digital images, as a step prior to segmentation. In specific, an analysis is made not only of the properties of the divergence used, but also of the method's sensitivity to the spatial variation, as well as the detection-error risk associated with the operating conditions due to the randomness of the spatial configuration of the pixels. Although the paper deals with the procedure based on the Jensen-Shannon divergence, some problems are also related to other methods based on local detection with a sliding window, and part of the study is focused to noisy and textured images. 相似文献
47.
随着J2EE开发平台的流行,应用程序一般都需要解决业务对象的持久化.本文通过对南昌市房改信息管理系统数据持久层设计的阐述,探讨了利用Hibernate技术实现数据持久化访问的优缺点,并总结了一些开发方面的建议. 相似文献
48.
49.
Three-dimensional quantitative structure-activity relationship (3D-QSAR) models were developed using comparative molecular field analysis (CoMFA) and comparative molecular similarity analysis (CoMSIA) on a series of agonists of thyroid hormone receptor beta (TRbeta), which may lead to safe therapies for non-thyroid disorders while avoiding the cardiac side effects. The reasonable q(2) (cross-validated) values 0.600 and 0.616 and non-cross-validated r(2) values of 0.974 and 0.974 were obtained for CoMFA and CoMSIA models for the training set compounds, respectively. The predictive ability of two models was validated using a test set of 12 molecules which gave predictive correlation coefficients (r(pred)(2)) of 0.688 and 0.674, respectively. The Lamarckian Genetic Algorithm (LGA) of AutoDock 4.0 was employed to explore the binding mode of the compound at the active site of TRbeta. The results not only lead to a better understanding of interactions between these agonists and the thyroid hormone receptor beta but also can provide us some useful information about the influence of structures on the activity which will be very useful for designing some new agonist with desired activity. 相似文献
50.
Evaluation of amplitude-based sorting algorithm to reduce lung tumor blurring in PET images using 4D NCAT phantom 总被引:1,自引:0,他引:1
Wang J Byrne J Franquiz J McGoron A 《Computer methods and programs in biomedicine》2007,87(2):112-122
PURPOSE: develop and validate a PET sorting algorithm based on the respiratory amplitude to correct for abnormal respiratory cycles. METHOD AND MATERIALS: using the 4D NCAT phantom model, 3D PET images were simulated in lung and other structures at different times within a respiratory cycle and noise was added. To validate the amplitude binning algorithm, NCAT phantom was used to simulate one case of five different respiratory periods and another case of five respiratory periods alone with five respiratory amplitudes. Comparison was performed for gated and un-gated images and for the new amplitude binning algorithm with the time binning algorithm by calculating the mean number of counts in the ROI (region of interest). RESULTS: an average of 8.87+/-5.10% improvement was reported for total 16 tumors with different tumor sizes and different T/B (tumor to background) ratios using the new sorting algorithm. As both the T/B ratio and tumor size decreases, image degradation due to respiration increases. The greater benefit for smaller diameter tumor and lower T/B ratio indicates a potential improvement in detecting more problematic tumors. 相似文献