全文获取类型
收费全文 | 43002篇 |
免费 | 14945篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 807篇 |
综合类 | 5篇 |
化学工业 | 18545篇 |
金属工艺 | 543篇 |
机械仪表 | 1216篇 |
建筑科学 | 1763篇 |
矿业工程 | 6篇 |
能源动力 | 1152篇 |
轻工业 | 7445篇 |
水利工程 | 295篇 |
石油天然气 | 46篇 |
无线电 | 7720篇 |
一般工业技术 | 12533篇 |
冶金工业 | 831篇 |
原子能技术 | 100篇 |
自动化技术 | 4954篇 |
出版年
2024年 | 5篇 |
2023年 | 91篇 |
2022年 | 48篇 |
2021年 | 430篇 |
2020年 | 1559篇 |
2019年 | 3300篇 |
2018年 | 3249篇 |
2017年 | 3575篇 |
2016年 | 4052篇 |
2015年 | 4086篇 |
2014年 | 4115篇 |
2013年 | 5316篇 |
2012年 | 3159篇 |
2011年 | 2885篇 |
2010年 | 3000篇 |
2009年 | 2871篇 |
2008年 | 2382篇 |
2007年 | 2139篇 |
2006年 | 1892篇 |
2005年 | 1585篇 |
2004年 | 1516篇 |
2003年 | 1500篇 |
2002年 | 1402篇 |
2001年 | 1215篇 |
2000年 | 1175篇 |
1999年 | 571篇 |
1998年 | 187篇 |
1997年 | 155篇 |
1996年 | 86篇 |
1995年 | 73篇 |
1994年 | 42篇 |
1993年 | 47篇 |
1992年 | 42篇 |
1991年 | 38篇 |
1990年 | 35篇 |
1989年 | 29篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 15篇 |
1985年 | 17篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1890年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
An Integrated Model of the Toyota Production System with Total Quality Management and People Factors
The Toyota production system (TPS), or lean production, has been associated with many benefits for manufacturing firms that implement the system. However, to implement the TPS successfully, it is necessary to integrate the so‐called “hard side” of the system (that is, the technical aspects of material handling) with the “soft side” of the program (that is, the aspects associated with human factors). The present study makes a contribution to such a holistic view of the TPS by proposing an integrated model that consists of the technical aspects of the TPS, together with elements associated with total quality management (TQM), human resources management (HRM), and certain identified “people factors.” The study then uses structural equation modeling (SEM) to test this holistic model using data obtained from a questionnaire survey of 153 Taiwanese manufacturing firms. The empirical study confirms the appropriateness of the causal model, which is evaluated by several goodness‐of‐fit methods. The study confirms the proposition that the inclusion of the “people factors” together with TQM and HRM significantly improves the realization of benefits associated with the TPS practices of “just‐in‐time” (JIT) and “autonomation.” The conclusion is that such an integrated model provides a much more effective “lean system” and has the potential to produce significantly enhanced benefits for firms that implement it. © 2012 Wiley Periodicals, Inc. 相似文献
942.
Capability of microstrip nonuniform transmission lines (MNTLs) for construction of dual‐band and broadband unequal Wilkinson power dividers with arbitrary‐way, arbitrary frequency band operations, and arbitrary power divisions is evaluated. Also, the MNTL transformers are introduced for dual‐band/broadband matching of the unequal output impedances of the MNTL power divider with arbitrary output terminal impedances. The strip width of MNTLs is considered variable and is written as a truncated Fourier series expansion. To show the validity of the design procedure, three experimental MNTL Wilkinson power dividers, which are dual‐band two‐ and three‐way power dividers with different power divisions working at 1 and 3.4 GHz and one broadband equal power divider working from 0.4 to 1.8 GHz, have been designed and fabricated. In the first ones with power division of 1.5, outputs isolation and ports matching of less than ?30 dB are achieved. Next, an extended recombinant structure is presented for achieving three‐way MNTL power dividers with dual‐band operation. The measured isolation between outputs and ports matching are better than 30 dB and measured forward transmissions are between ?4.87 and ?5.45 in two passbands of the divider. Also, for the proposed broadband divider, the measured isolation between the outputs is better than 13 dB in 127% desired bandwidth. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. 相似文献
943.
A novel parametric modeling technique is proposed to develop combined neural network and transfer function models for both time and frequency (TF) domain applications of passive components, where the neural network is trained to map geometrical variables to the coefficients of transfer functions. Built on our previous work, a new order‐changing module is developed to enforce stability of transfer functions and simultaneously guarantee continuity of coefficients. A constrained optimization strategy is introduced to enforce passivity of transfer functions through a neural network training process. A general equivalent circuit for two‐port passive components is generated directly from coefficients of arbitrary‐order transfer functions. Once trained, the parametric model can provide accurate and fast prediction of the electromagnetic behavior of passive components with geometrical parameters as variables. Compared to our previous work, the proposed method enables models to work well in the time domain providing good accuracy in challenging modeling applications. Two parametric modeling examples of spiral inductors and interdigital capacitors, and their application in both time and frequency domain simulations of a power amplifier are examined to demonstrate the validity of the proposed technique. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2013. 相似文献
944.
In this article, the neural network approach is exploited for development of bias‐dependent small‐signal and noise models of a class of microwave field effect transistor (FETs) made in the same technology but differing in the gate width. The prior knowledge neural approach is applied. Introducing gate width at the input of proposed neural networks, as well as the S/noise parameters of a device that belongs to the same class as the modeled device representing the prior knowledge, leads to very accurate scattering and noise parameters' modeling, as exemplified by modeling of class of pseudomorphic high electron mobility transistor (pHEMT) devices. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. 相似文献
945.
By etching slots in the low‐impedance section of the conventional stepped‐impedance resonator, a novel slotted stepped‐impedance resonator (SSIR) is proposed. As two examples, a fourth‐order bandpass filter (BPF) operating at 1 GHz with a size of 0.078 λg × 0.062 λg and a miniaturized diplexer operating at 0.9/1.57 GHz with a size of 0.054 λ0 × 0.086 λ0 are designed based on the proposed SSIR. The fabricated BPF exhibits a high selectivity and a wide ?30 dB rejection upper stopband from 1.13 f0 to 6.52 f0, while the fabricated diplexer has up to ?60 dB output isolation. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. 相似文献
946.
Nadia Magnenat Thalmann Igor Sunday Pandzic Jean‐Claude Moussaly 《Digital Creativity》2013,24(2):59-66
Abstract This paper describes the making of a short film on the Xian terra‐cotta soldiers using our integrated HU‐MANOID software. The method of creating and animating the soldiers’ faces is first presented. Then, we show how our approach, based on metaballs and spline surfaces, was used for designing and deforming soldiers’ bodies. For the animation of the bodies, we describe the motion control methods. Clothes for the soldiers are then described as well as horses and decor design. For the rendering, we explained our strategy using parallel machines. Finally, problems of integration are addressed. 相似文献
947.
Wolff‐Michael Roth 《Canadian Journal of Science, Mathematics, & Technology Education》2013,13(1):37-48
Abstract The shape and content of science education has always been articulated from the scientist's perspective. Recently, an increasing number of science educators have recognized the serious limitations of this perspective and have proposed to define scientific literacy from societal or citizenship perspectives. In this article, I argue that these alternatives will remain as limited as their predecessors unless the very structures of schooling are called into question. Furthermore, I argue that alternatives cannot be designed at the drawing board by theoreticians, but have to be grounded in praxis, thereby providing concrete trajectories along which science education can actually change. 相似文献
948.
Cui‐Zhen Yao 《Asian journal of control》2013,15(5):1531-1537
This article considers stabilization of a one‐dimensional Schrödinger equation with variable coefficient and boundary observation which suffers from an arbitrary given time delay. We design an observer and predictor to stabilize the system. The state is estimated in the time span where the observation is available, and also predicted in the time interval where the observation is not available. It is shown that the estimated state feedback stabilizes the system exponentially. A numerical simulation is presented to illustrate the effect of the stabilizing controller. 相似文献
949.
Chih‐Keng Chen 《Asian journal of control》2013,15(4):1036-1050
In this study, a genetic‐fuzzy control system is used to control a riderless bicycle where control parameters can adapt to the speed change of the bicycle. The equations of motion are developed for a bicycle with constraints of rolling‐without‐slipping contact condition between the wheels and ground. This controller consists of two loops: the inner is a roll‐angle‐tracking controller which generates steering torque to control the roll angle while guaranteeing the stability, and the outer is a path‐tracking controller which generates the reference roll angle for the inner loop. The inner loop is a sliding‐mode controller (SMC) designed on the basis of a linear model obtained from a system identification process. By defining a stable sliding surface of error dynamics and an appropriate Lyapunov function, the bicycle can reach the roll‐angle reference in a finite time and follow that reference without chattering. The outer loop determines the proper reference roll‐angle by using a fuzzy‐logic controller (FLC) in which previewing and tracking errors are taken into consideration. The robustness of the proposed controller against speed change and external disturbances is verified by simulations. 相似文献
950.
Tzung‐Feng Lin 《Asian journal of control》2013,15(4):1011-1020
Conventional Q‐learning requires pre‐defined quantized state space and action space. It is not practical for real robot applications since discrete and finite numbers of action sets cannot precisely identify the variances in the different positions on the same state element on which the robot is located. In this paper, a Q‐Learning composed continuous action generator, called the fuzzy cerebellar model articulation controller (FCMAC) method, is presented to solve the problem. The FCMAC displays continuous action generation by linear combination of the weighting distribution of the state space where the optimal policy of each state is derived from Q‐learning. This provides better resolution of the weighting distribution for the state space where the robot is located. The algorithm not only solves the single‐agent problem but also solves the multi‐agent problem by extension. An experiment is implemented in a task where two robots are taking action independently and both are connected with a straight bar. Their goal is to cooperate with each other to pass through a gate in the middle of a grid environment. 相似文献