全文获取类型
收费全文 | 1257篇 |
免费 | 69篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 13篇 |
综合类 | 3篇 |
化学工业 | 272篇 |
金属工艺 | 17篇 |
机械仪表 | 41篇 |
建筑科学 | 33篇 |
能源动力 | 65篇 |
轻工业 | 52篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 220篇 |
一般工业技术 | 218篇 |
冶金工业 | 117篇 |
原子能技术 | 13篇 |
自动化技术 | 268篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 21篇 |
2021年 | 40篇 |
2020年 | 27篇 |
2019年 | 26篇 |
2018年 | 30篇 |
2017年 | 41篇 |
2016年 | 55篇 |
2015年 | 47篇 |
2014年 | 42篇 |
2013年 | 101篇 |
2012年 | 71篇 |
2011年 | 76篇 |
2010年 | 57篇 |
2009年 | 63篇 |
2008年 | 80篇 |
2007年 | 70篇 |
2006年 | 37篇 |
2005年 | 40篇 |
2004年 | 39篇 |
2003年 | 35篇 |
2002年 | 31篇 |
2001年 | 31篇 |
2000年 | 20篇 |
1999年 | 11篇 |
1998年 | 39篇 |
1997年 | 29篇 |
1996年 | 22篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 19篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1972年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有1335条查询结果,搜索用时 11 毫秒
61.
High Sensitivity,Wearable, Piezoresistive Pressure Sensors Based on Irregular Microhump Structures and Its Applications in Body Motion Sensing 下载免费PDF全文
Zongrong Wang Shan Wang Jifang Zeng Xiaochen Ren Adrian J. Y. Chee Billy Y. S. Yiu Wai Choi Chung Yong Yang Alfred C. H. Yu Robert C. Roberts Anderson C. O. Tsang Kwok Wing Chow Paddy K. L. Chan 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(28):3827-3836
A pressure sensor based on irregular microhump patterns has been proposed and developed. The devices show high sensitivity and broad operating pressure regime while comparing with regular micropattern devices. Finite element analysis (FEA) is utilized to confirm the sensing mechanism and predict the performance of the pressure sensor based on the microhump structures. Silicon carbide sandpaper is employed as the mold to develop polydimethylsiloxane (PDMS) microhump patterns with various sizes. The active layer of the piezoresistive pressure sensor is developed by spin coating PEDOT:PSS on top of the patterned PDMS. The devices show an averaged sensitivity as high as 851 kPa?1, broad operating pressure range (20 kPa), low operating power (100 nW), and fast response speed (6.7 kHz). Owing to their flexible properties, the devices are applied to human body motion sensing and radial artery pulse. These flexible high sensitivity devices show great potential in the next generation of smart sensors for robotics, real‐time health monitoring, and biomedical applications. 相似文献
62.
Chiung Ching Ho Hu Ng Wooi-Haw Tan Kok-Why Ng Hau-Lee Tong Timothy Tzen-Vun Yap Pei-Fen Chong C. Eswaran Junaidi Abdullah 《Pattern recognition letters》2013
This paper describes the baseline corpus of a new multimodal biometric database, the MMU GASPFA (Gait–Speech–Face) database. The corpus in GASPFA is acquired using commercial off the shelf (COTS) equipment including digital video cameras, digital voice recorder, digital camera, Kinect camera and accelerometer equipped smart phones. The corpus consists of frontal face images from the digital camera, speech utterances recorded using the digital voice recorder, gait videos with their associated data recorded using both the digital video cameras and Kinect camera simultaneously as well as accelerometer readings from the smart phones. A total of 82 participants had their biometric data recorded. MMU GASPFA is able to support both multimodal biometric authentication as well as gait action recognition. This paper describes the acquisition setup and protocols used in MMU GASPFA, as well as the content of the corpus. Baseline results from a subset of the participants are presented for validation purposes. 相似文献
63.
64.
Hongyi Yang Jingying Charlotte Lim Yuchan Liu Xiaoying Qi Yee Ling Yap Vishwesh Dikshit 《Virtual and Physical Prototyping》2017,12(1):95-103
The purpose of this paper is to quantitatively evaluate the performance of a multi-material jetting 3D printer, ProJet 5500X, especially the capability for micro manufacturing. Unlike other single material 3D printer, ProJet 5500X uses photopolymers as the build material and wax as the support material. The building performance was evaluated by building a modified version of the standard benchmark model with a high-resolution printing mode. The dimensional error, forming quality and surface roughness of the printed parts have been measured and analysed using a microscope, a 3D coordinate measuring machine and a surface profilometer. Using wax as the support material, fine features as small as 0.25?mm, lateral features and sharper edges could all be properly built, despite the rough side surfaces observed in the printed part. Identical features (3?mm pins) were precisely built with an accuracy of 15?µm. The research provides first-hand detailed performance knowledge in the ProJet system for understanding the working principle and comparison with other 3D printing systems. 相似文献
65.
People involved in business are increasingly aware of the online social phenomenon and its potential as a marketing tool. Building upon the marketing, social psychology, and information system literature, this study empirically examines a set of functional determinants derived from the technology acceptance model and socio-psychological determinants drawn from the theory of reasoned action and social cognitive theory that may be responsible for the motivations of participants in online social networks. We propose a model by integrating functional, social, and psychological factors in predicting attitude and online social network usage. The survey outcomes from a cross-sectional study among 387 Facebook users in Malaysia support the hypothesised model. This study contributes by extending the cognitive learning theories in predicting online social networking usage. Particularly, this research presents a different perspective on online social networking by exploring the mediating effect of attitude and the moderating role of individual characteristics. This study demonstrates that desirable changes in the perception of functional benefits, self-efficacy, and need for cognition as well as perceptions of social pressure from significant others might lead to corresponding changes in attitude towards online social networking. Results of the study support the model efficacy and predictive ability of the proposed integrative model which may serve as a theoretical foundation for future researchers interested in examining other virtual community engagements such as blogging, online advertising, and online public relations activities. 相似文献
66.
Noraini Nordin Samikannu Kanagesan Nur Rizi Zamberi Swee Keong Yeap Nadiah Abu Subramani Tamilselvan Mansor Hashim Noorjahan Banu Alitheen 《IET nanobiotechnology / IET》2017,11(3):343
In this study, nanocrystalline magnesium zinc ferrite nanoparticles were successfully prepared by a simple sol–gel method using copper nitrate and ferric nitrate as raw materials. The calcined samples were characterised by differential thermal analysis/thermogravimetric analysis, Fourier transform infrared spectroscopy and X‐ray diffraction. Transmission electron microscopy revealed that the average particle size of the calcined sample was in a range of 17–41 nm with an average of 29 nm and has spherical size. A cytotoxicity test was performed on human breast cancer cells (MDA MB‐231) and (MCF‐7) at various concentrations starting from (0 µg/ml) to (800 µg/ml). The sample possessed a mild toxic effect toward MDA MB‐231 and MCF‐7 after being examined with MTT (3‐[4, 5‐dimethylthiazol‐2‐yl]‐2, 5 diphenyltetrazolium bromide) assay for up to 72 h of incubation. Higher reduction of cells viability was observed as the concentration of sample was increased in MDA MB‐231 cell line than in MCF‐7. Therefore, further cytotoxicity tests were performed on MDA MB‐231 cell line.Inspec keywords: sol‐gel processing, nanoparticles, nanofabrication, magnesium compounds, zinc compounds, toxicology, biological organs, cancer, cellular biophysics, nanomedicine, calcination, differential thermal analysis, Fourier transform infrared spectra, X‐ray diffraction, transmission electron microscopy, particle size, organic compoundsOther keywords: sol‐gel method, cytotoxic effects, breast cancer cell line, MDA MB‐231 in vitro, nanocrystalline magnesium zinc ferrite nanoparticles, copper nitrate, ferric nitrate, raw materials, calcined samples, differential thermal analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, average particle size, cytotoxicity testing, human breast cancer cells, mild toxic effect, 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5 diphenyltetrazolium bromide) assay, cell viability, MCF‐7, MDA MB‐231 cell line, size 17 nm to 41 nm 相似文献
67.
Tensile Strength Characteristics of Unsaturated Sands 总被引:5,自引:0,他引:5
Tensile strength characteristics of unsaturated sands are examined through a combined theoretical and experimental study. The characteristics of tensile strength in all three water retention regimes of pendular, funicular, and capillary are examined. A simple direct tensile strength apparatus is employed to determine tensile strength for sands with a broad range of particle sizes from silty sand to fine sand and medium sand over a full range of degree of saturation. Tensile strength characteristic curves (TSCC) are established experimentally for these sands and are used to validate the existing theories for tensile strength in the pendular regime. The TSCC for sand characteristically exhibits two zeros at 0 and near 100% saturation, and two peak values occurring in the pendular and capillary regimes, respectively. A minimum tensile strength is observed in the dense fine sand, indicating that either water bridges or pore pressure contributes exclusively to the tensile strength in the funicular regime of this sand. The maximum tensile strength for the silty sand is 1,448?Pa, the fine sand is 1,416?Pa, and the medium sand is 890?Pa. Comparison between the soil–water characteristic curves obtained for these sands indicates that the peak tensile strength in the capillary regime is highly correlated to the air-entry pressure. Photographs of the failure surfaces clearly delineate distinct geometric characteristics for different water retention regimes. Analysis of the patterns of failure surfaces in different water retention regimes indicates that the effective stress principle is valid for tensile stress failure in unsaturated sands. 相似文献
68.
Joxan Jaffar Michael J. Maher Peter J. Stuckey Roland H. C. Yap 《New Generation Computing》1993,11(3-4):449-469
The presentation of constraints in a usable form is an essential aspect of Constraint Logic Programming (CLP) systems. It is needed both in the output of constraints, as well as in the production of an internal representation of constraints for meta-level manipulation. Typically, only a small subset \(\tilde x\) of the variables in constraints is of interest, and so an informal statement of the problem at hand is: given a conjunction \(c(\tilde x,\tilde y)\) of constraints, express the projection \(\exists \tilde y c(\tilde x,\tilde y)\) ofc onto \(\tilde x\) in the simplest form. In this paper, we consider the constraints of the CLP(R) system and describe the essential features of its projection module. One main part focuses on the well-known problem of projection inlinear arithmetic constraints. We start with a classical algorithm and augment it with a procedure for eliminating redundant constraints generated by the algorithm. A second part discusses projection of the other object-level constraints: equations over trees and nonlinear equations. The final part deals with producing a manipulable form of the constraints, which complicates the projection problem. 相似文献
69.
Sub‐Micron Anisotropic InP‐based III–V Semiconductor Material Deep Etching for On‐Chip Laser Photonics Devices 下载免费PDF全文
Doris Keh‐Ting Ng Chee Wei Lee Vivek Krishnamurthy Qian Wang 《Advanced Engineering Materials》2018,20(2)
70.