全文获取类型
收费全文 | 5126篇 |
免费 | 132篇 |
国内免费 | 39篇 |
专业分类
电工技术 | 93篇 |
综合类 | 5篇 |
化学工业 | 992篇 |
金属工艺 | 122篇 |
机械仪表 | 199篇 |
建筑科学 | 97篇 |
能源动力 | 193篇 |
轻工业 | 231篇 |
水利工程 | 27篇 |
石油天然气 | 4篇 |
无线电 | 905篇 |
一般工业技术 | 913篇 |
冶金工业 | 564篇 |
原子能技术 | 25篇 |
自动化技术 | 927篇 |
出版年
2024年 | 9篇 |
2023年 | 31篇 |
2022年 | 111篇 |
2021年 | 108篇 |
2020年 | 35篇 |
2019年 | 56篇 |
2018年 | 66篇 |
2017年 | 76篇 |
2016年 | 101篇 |
2015年 | 102篇 |
2014年 | 177篇 |
2013年 | 374篇 |
2012年 | 269篇 |
2011年 | 323篇 |
2010年 | 232篇 |
2009年 | 266篇 |
2008年 | 271篇 |
2007年 | 241篇 |
2006年 | 229篇 |
2005年 | 197篇 |
2004年 | 162篇 |
2003年 | 157篇 |
2002年 | 126篇 |
2001年 | 116篇 |
2000年 | 86篇 |
1999年 | 99篇 |
1998年 | 250篇 |
1997年 | 150篇 |
1996年 | 114篇 |
1995年 | 72篇 |
1994年 | 96篇 |
1993年 | 61篇 |
1992年 | 45篇 |
1991年 | 54篇 |
1990年 | 36篇 |
1989年 | 45篇 |
1988年 | 53篇 |
1987年 | 39篇 |
1986年 | 32篇 |
1985年 | 24篇 |
1984年 | 28篇 |
1983年 | 24篇 |
1982年 | 11篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 18篇 |
1976年 | 34篇 |
1974年 | 7篇 |
排序方式: 共有5297条查询结果,搜索用时 15 毫秒
81.
Optimizing the orthopaedic screws can greatly improve their biomechanical performances. However, a methodical design optimization approach requires a long time to search the best design. Thus, the surrogate objective functions of the orthopaedic screws should be accurately developed. To our knowledge, there is no study to evaluate the strengths and limitations of the surrogate methods in developing the objective functions of the orthopaedic screws. Three-dimensional finite element models for both the tibial locking screws and the spinal pedicle screws were constructed and analyzed. Then, the learning data were prepared according to the arrangement of the Taguchi orthogonal array, and the verification data were selected with use of a randomized selection. Finally, the surrogate objective functions were developed by using either the multiple linear regression or the artificial neural network. The applicability and accuracy of those surrogate methods were evaluated and discussed. The multiple linear regression method could successfully construct the objective function of the tibial locking screws, but it failed to develop the objective function of the spinal pedicle screws. The artificial neural network method showed a greater capacity of prediction in developing the objective functions for the tibial locking screws and the spinal pedicle screws than the multiple linear regression method. The artificial neural network method may be a useful option for developing the objective functions of the orthopaedic screws with a greater structural complexity. The surrogate objective functions of the orthopaedic screws could effectively decrease the time and effort required for the design optimization process. 相似文献
82.
Bio-chemical networks are often modeled as systems of ordinary differential equations (ODEs). Such systems will not admit closed form solutions and hence numerical simulations will have to be used to perform analyses. However, the number of simulations required to carry out tasks such as parameter estimation can become very large. To get around this, we propose a discrete probabilistic approximation of the ODEs dynamics. We do so by discretizing the value and the time domain and assuming a distribution of initial states w.r.t. the discretization. Then we sample a representative set of initial states according to the assumed initial distribution and generate a corresponding set of trajectories through numerical simulations. Finally, using the structure of the signaling pathway we encode these trajectories compactly as a dynamic Bayesian network.This approximation of the signaling pathway dynamics has several advantages. First, the discretized nature of the approximation helps to bridge the gap between the accuracy of the results obtained by ODE simulation and the limited precision of experimental data used for model construction and verification. Second and more importantly, many interesting pathway properties can be analyzed efficiently through standard Bayesian inference techniques instead of resorting to a large number of ODE simulations. We have tested our method on ODE models of the EGF-NGF signaling pathway [1] and the segmentation clock pathway [2]. The results are very promising in terms of accuracy and efficiency. 相似文献
83.
Valley J.K. Jamshidi A. Ohta A.T. Hsan-Yin Hsu Wu M.C. 《Journal of microelectromechanical systems》2008,17(2):342-350
Optoelectronic tweezers (OET) are a powerful light-based technique for the manipulation of micro- and nanoscopic particles. In addition to an optically patterned dielectrophoresis (DEP) force, other light-induced electrokinetic and thermal effects occur in the OET device. In this paper, we present a comprehensive theoretical and experimental investigation of various fluidic, optical, and electrical effects present during OET operation. These effects include DEP, light-induced ac electroosmosis, electrothermal flow, and buoyancy-driven flow. We present finite-element modeling of these effects to establish the dominant mode for a given set of device parameters and bias conditions. These results are confirmed experimentally and present a comprehensive outline of the operational regimes of the OET device. 相似文献
84.
Chueh-Yu Li Chiou-Ting Hsu 《Multimedia, IEEE Transactions on》2008,10(3):447-456
This paper presents a graph-theoretic approach for interactive region-based image retrieval. When dealing with image matching problems, we use graphs to represent images, transform the region correspondence estimation problem into an inexact graph matching problem, and propose an optimization technique to derive the solution. We then define the image distance in terms of the estimated region correspondence. In the relevance feedback steps, with the estimated region correspondence, we propose to use a maximum likelihood method to re-estimate the ideal query and the image distance measurement. Experimental results show that the proposed graph-theoretic image matching criterion outperforms the other methods incorporating no spatially adjacent relationship within images. Furthermore, our maximum likelihood method combined with the estimated region correspondence improves the retrieval performance in feedback steps. 相似文献
85.
A confidence-based framework for business to consumer (B2C) mobile commerce adoption 总被引:1,自引:0,他引:1
The Technology Acceptance Model (TAM) has been considered to be fundamental in determining the acceptance of new technology
in the past decades. The two beliefs, ease of use and usefulness, in the model may not, however, fully explain the consumers’
behavior in an emerging environment, such as mobile commerce (m-commerce). This paper aims to develop a framework for m-commerce
adoption in consumer decision-making processes. In this paper TAM has been adopted and extended to analyze successful m-commerce
adoption. The key elements of the proposed confidence-based framework for B2C m-commerce adoption include psychological and
behavioral factors. Psychological factors include history-based confidence, institution-based confidence and personality-based
confidence. Behavioral factors include perceived ease of use and perceived usefulness of the mobile application and technology. 相似文献
86.
Cheng-Hsing Hsu Po-Chuang Chen Kuang-Yuan Kung Chuan Lai 《The International Journal of Advanced Manufacturing Technology》2007,31(7-8):673-681
The flow field of a long bubble steadily expelling a viscous fluid confined by two closely located parallel plates is examined.
In order to investigate the influence of bubble size on the flow field, a theoretical bubble profile is used to replace the
complicated procedure for computing simultaneously the interface between the gas surface and fluid flows. The present study
showed the two typical flow patterns and also a third flow pattern of the stagnation point moving in the region of the bubble
tip front during transformation of the two typical flow patterns. The vorticity patterns are also drawn for various bubble
profiles and are examined for their effect on the flow. The velocity field is also presented from two different viewpoints
and the phenomena is examined. The stagnation point located on the center line between the bubble tip to the upstream is only
found in the small range of in a channel, where λ is ratio of the bubble width to the distance between two parallel plates. 相似文献
87.
88.
Jian WS Hsu CY Hao TH Wen HC Hsu MH Lee YL Li YC Chang P 《Computer methods and programs in biomedicine》2007,88(2):102-111
Traditional electronic health record (EHR) data are produced from various hospital information systems. They could not have existed independently without an information system until the incarnation of XML technology. The interoperability of a healthcare system can be divided into two dimensions: functional interoperability and semantic interoperability. Currently, no single EHR standard exists that provides complete EHR interoperability. In order to establish a national EHR standard, we developed a set of local EHR templates. The Taiwan Electronic Medical Record Template (TMT) is a standard that aims to achieve semantic interoperability in EHR exchanges nationally. The TMT architecture is basically composed of forms, components, sections, and elements. Data stored in the elements which can be referenced by the code set, data type, and narrative block. The TMT was established with the following requirements in mind: (1) transformable to international standards; (2) having a minimal impact on the existing healthcare system; (3) easy to implement and deploy, and (4) compliant with Taiwan's current laws and regulations. The TMT provides a basis for building a portable, interoperable information infrastructure for EHR exchange in Taiwan. 相似文献
89.
Guo Y Hsu S Sawhney HS Kumar R Shan Y 《IEEE transactions on pattern analysis and machine intelligence》2007,29(5):824-839
This paper addresses the problem of matching vehicles across multiple sightings under variations in illumination and camera poses. Since multiple observations of a vehicle are separated in large temporal and/or spatial gaps, thus prohibiting the use of standard frame-to-frame data association, we employ features extracted over a sequence during one time interval as a vehicle fingerprint that is used to compute the likelihood that two or more sequence observations are from the same or different vehicles. Furthermore, since our domain is aerial video tracking, in order to deal with poor image quality and large resolution and quality variations, our approach employs robust alignment and match measures for different stages of vehicle matching. Most notably, we employ a heterogeneous collection of features such as lines, points, and regions in an integrated matching framework. Heterogeneous features are shown to be important. Line and point features provide accurate localization and are employed for robust alignment across disparate views. The challenges of change in pose, aspect, and appearances across two disparate observations are handled by combining a novel feature-based quasi-rigid alignment with flexible matching between two or more sequences. However, since lines and points are relatively sparse, they are not adequate to delineate the object and provide a comprehensive matching set that covers the complete object. Region features provide a high degree of coverage and are employed for continuous frames to provide a delineation of the vehicle region for subsequent generation of a match measure. Our approach reliably delineates objects by representing regions as robust blob features and matching multiple regions to multiple regions using Earth Mover's Distance (EMD). Extensive experimentation under a variety of real-world scenarios and over hundreds of thousands of Confirmatory Identification (CID) trails has demonstrated about 95 percent accuracy in vehicle reacquisition with both visible and Infrared (IR) imaging cameras. 相似文献
90.