全文获取类型
收费全文 | 26988篇 |
免费 | 3570篇 |
国内免费 | 2743篇 |
专业分类
电工技术 | 2676篇 |
技术理论 | 1篇 |
综合类 | 3736篇 |
化学工业 | 2357篇 |
金属工艺 | 1950篇 |
机械仪表 | 1952篇 |
建筑科学 | 712篇 |
矿业工程 | 389篇 |
能源动力 | 405篇 |
轻工业 | 749篇 |
水利工程 | 213篇 |
石油天然气 | 369篇 |
武器工业 | 339篇 |
无线电 | 3622篇 |
一般工业技术 | 4597篇 |
冶金工业 | 516篇 |
原子能技术 | 188篇 |
自动化技术 | 8530篇 |
出版年
2024年 | 77篇 |
2023年 | 364篇 |
2022年 | 582篇 |
2021年 | 826篇 |
2020年 | 820篇 |
2019年 | 891篇 |
2018年 | 787篇 |
2017年 | 1066篇 |
2016年 | 1073篇 |
2015年 | 1293篇 |
2014年 | 1681篇 |
2013年 | 1957篇 |
2012年 | 1963篇 |
2011年 | 2062篇 |
2010年 | 1676篇 |
2009年 | 1853篇 |
2008年 | 1677篇 |
2007年 | 1947篇 |
2006年 | 1616篇 |
2005年 | 1428篇 |
2004年 | 1215篇 |
2003年 | 960篇 |
2002年 | 797篇 |
2001年 | 723篇 |
2000年 | 637篇 |
1999年 | 530篇 |
1998年 | 438篇 |
1997年 | 375篇 |
1996年 | 349篇 |
1995年 | 325篇 |
1994年 | 275篇 |
1993年 | 227篇 |
1992年 | 176篇 |
1991年 | 139篇 |
1990年 | 123篇 |
1989年 | 89篇 |
1988年 | 67篇 |
1987年 | 43篇 |
1986年 | 26篇 |
1985年 | 23篇 |
1984年 | 21篇 |
1983年 | 21篇 |
1982年 | 15篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Menglong YangAuthor Vitae Yiguang LiuAuthor VitaeZhisheng YouAuthor Vitae 《Neurocomputing》2011,74(17):3638-3645
The epipolar geometry is the intrinsic projective geometry between two views, and the algebraic representation of it is the fundamental matrix. Estimating the fundamental matrix requires solving an over-determined equation. Many classical approaches assume that the error values of the over-determined equation obey a Gaussian distribution. However, the performances of these approaches may decrease significantly when the noise is large and heterogeneous. This paper proposes a novel technique for estimating the fundamental matrix based on least absolute deviation (LAD), which is also known as the L1 method. Then a linear iterative algorithm is presented. The experimental results on some indoor and outdoor scenes show that the proposed algorithm yields the accurate and robust estimates of the fundamental matrix when the noise is non-Gaussian. 相似文献
992.
Bo ZhouAuthor VitaeQiankun SongAuthor Vitae Huiwei WangAuthor Vitae 《Neurocomputing》2011,74(17):3142-3150
By employing time scale calculus theory, free weighting matrix method and linear matrix inequality (LMI) approach, several delay-dependent sufficient conditions are obtained to ensure the existence, uniqueness and global exponential stability of the equilibrium point for the neural networks with both infinite distributed delays and general activation functions on time scales. Both continuous-time and discrete-time neural networks are described under the same framework by the reported method. Illustrated numerical examples are given to show the effectiveness of the theoretical analysis. It is noteworthy that the activation functions are assumed to be neither bounded nor monotone. 相似文献
993.
Emilia L. ApostolovaAuthor Vitae Anelia G. DobrikovaAuthor VitaeGeorgi D. RashkovAuthor Vitae Kolyo G. DankovAuthor VitaeRadka S. VladkovaAuthor Vitae Amarendra N. MisraAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(1):140-146
Freshly prepared pea thylakoid membranes were immobilized in bovine serum albumin-glutaraldehyde cross-linked matrix (BSA-GA matrix) and their stability under long term storage was analyzed by Pulse-Amplitude-Modulated (PAM) chlorophyll fluorescence and photosynthetic oxygen evolution measured by oxygen rate electrode. The thylakoid membranes stored at 4 °C showed prolonged stability in BSA-GA matrix and additional adsorption on nitrocellulose membrane filters gave them more stability. The sensitivity of the parameters of the oxygen evolution of thylakoid membranes to atrazine increased with immobilization. The half-inhibition time for oxygen evolution and quantum efficiency of photosynthesis could be prolonged to more than 15 days. These results suggest that the immobilized thylakoid membranes in BSA-GA matrix can be used as biological receptor in biosensors for a long period of time (up to 25 days) applying the proposed new method for atrazine detection by using polarographic oxygen rate electrode. This method is more sensitive, faster and easier to use than other methods for detection of herbicides based on determination of the photochemical activity of photosystem II. 相似文献
994.
Maciej PilarekAuthor Vitae Peter NeubauerAuthor VitaeUwe MarxAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(2):517-526
Bio-hybrid microsystems actuated by living cells, as micro-bio-actuators and micro-bio-pumps have been developed recently. In these devices biological cells may be powered without external energy sources and the movement or the contraction of muscle cells trigger off the flow of fluid (i.e. culture medium or blood) through microchannels in micro-multi-bioreactor systems. Isolated and in vitro cultured cardiomyocytes (cardiac cells) are the most promising bio-material, which can be used to design a micro-bio-pump/actuator. These spontaneously contracting cells are autonomously powered with glucose as an energy source without any external power supply or stimulus, unlike conventional micro-actuators/micro-pumps. Cardio-micro-bio-pumps/actuators are using collective, synchronous contracting forces of cardiac cells or cardiac cell sheets to drive the flow of fluid. The feasibility of building such actuators was demonstrated in a few examples of bio-hybrid microsystems actuated by single or sheeted cardiomyocytes. 相似文献
996.
属性约筒是粗糙集理论的重要研究内容之一,以浓缩树结构存储区分矩阵中的非空数据项,对IReductBtree算法进行了一些改进.它是根据树结构特点结合特殊的启发式策略,删除树中结点,直到树空最后得到信息系统的一个约简.最后,通过一个实例完整演示了该方法证实其有效性. 相似文献
997.
998.
999.
基于二维混合模型和状态观测器的重复控制设计 总被引:1,自引:0,他引:1
针对一类正则线性系统, 提出一种基于状态观测器和二维混合模型的重复控制系统设计方法. 首先, 通过构造一个状态观测器来重构系统的状态, 建立基于重构状态的线性控制律. 然后, 通过独立地考虑重复控制系统的连续控制过程与离散学习行为, 给出基于状态观测器和重构状态反馈的连续/离散二维混合模型. 针对这个混合模型, 运用二维Lyapunov泛函方法, 以线性矩阵不等式(Linear matrix inequality, LMI)的形式给出重复控制系统存在重复控制器和状态观测器的充分条件, 所给条件可用Matlab工具箱方便地求解. 数值仿真验证了本文所提方法的有效性. 相似文献
1000.