全文获取类型
收费全文 | 552篇 |
免费 | 25篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 578篇 |
出版年
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 19篇 |
2016年 | 14篇 |
2015年 | 6篇 |
2014年 | 20篇 |
2013年 | 30篇 |
2012年 | 31篇 |
2011年 | 28篇 |
2010年 | 23篇 |
2009年 | 15篇 |
2008年 | 29篇 |
2007年 | 28篇 |
2006年 | 22篇 |
2005年 | 27篇 |
2004年 | 21篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 8篇 |
1998年 | 16篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1974年 | 4篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 5篇 |
排序方式: 共有578条查询结果,搜索用时 0 毫秒
1.
2.
Alain B. Kounga Njiwa Theo Fett Doru C. Lupascu Jürgen Rödel 《Journal of the American Ceramic Society》2003,86(11):1973-1975
Crack–opening displacement (COD) measurements were performed on a commercial lead zirconate titanate (PZT). The intrinsic fracture toughness (or crack–tip toughness) of this material was determined using a new evaluation procedure, which takes into account the near–tip CODs and complete crack profile CODs. The crack–tip toughness K I0 was determined from an extrapolation of COD data obtained at various loading stages, thus avoiding the complications caused by subcritical crack growth in PZT. Results for plane strain and plane stress condition are presented. 相似文献
3.
Keshun Liu Susan Seegers Wenming Cao Janitha Wanasundara Juxing Chen Alessandro Esteves da Silva Kristopher Ross Alexandra Lozano Franco Theo Vrijenhoek Pankaj Bhowmik Yonghui Li Xin Wu Scott Bloomer 《Journal of the American Oil Chemists' Society》2021,98(4):375-390
For determining trypsin inhibitor activity (TIA) in soy products, the American Oil Chemists' Society (AOCS) Method Ba 12-75 has been used. It measures differences in absorbance at 410 nm of bovine trypsin activity toward a synthetic substrate (Nα-benzoyl-DL-arginine-p-nitroanilide) in the absence and presence of an inhibitor. Recently, a significantly improved method was developed (JAOCS, 2019, 96:635–645), featuring 5 mL of total assay volume, enzyme-last sequence, and single inhibitor level in duplicate. It is proposed as the AOCS Method Ba 12a-2020. As a part of the AOCS method approval process, a collaborative study involving 12 international laboratories was conducted to evaluate the performance of the proposed method. The study involved measuring TIA in 10 selected test samples plus a blind duplicate. They included soybeans, pulses, cereals, and their processed products (flours, concentrates, and isolates). After rigorous statistical treatment of the data, only three outliers were removed from the data of two samples. Repeatability relative standard deviations (RSDr) for the 11 samples ranged from 0.99% to 5.52%. Reproducibility RSD (RSDR) ranged from 7.07% to 22.92%, with seven samples having RSDR around 10% or less. The remaining four samples had very low TIA, and their RSDR values ranged from 13.34% to 22.92%. The study has demonstrated reliable performance of the proposed AOCS method. Several collaborators carried out additional experiments addressing some aspects of the method, leading to further refinements. The proposed method is undergoing evaluation by the AOCS Uniform Methods Committee for adoption as an Official Method for measuring TIA in various legume and grain products. 相似文献
4.
Takeo Uchida Keita Abe Yuma Endo Shosei Ichiseki Satoru Akita Shiyun Liu Sho Aradachi Masataka Saito Akihiko Fukuchi Taiyo Kikkawa Theo Dammaretz Ibuki Kawamata Yuki Suzuki Shin‐ichiro M. Nomura Satoshi Murata 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(41)
A new kind of the Vernier mechanism that is able to control the size of linear assembly of DNA origami nanostructures is proposed. The mechanism is realized by mechanical design of DNA origami, which consists of a hollow cylinder and a rotatable shaft in it connected through the same scaffold. This nanostructure stacks with each other by the shape complementarity at its top and bottom surfaces of the cylinder, while the number of stacking is limited by twisting angle of the shaft. Experiments have shown that the size distribution of multimeric assembly of the origami depends on the twisting angle of the shaft; the average lengths of the multimer are decamer, hexamer, and tetramer for 0°, 10°, and 20° twist, respectively. In summary, it is possible to affect the number of polymerization by adjusting the precise shape and movability of a molecular structure. 相似文献
5.
Jose M. Álvarez Theo Gevers Antonio M. López 《International Journal of Computer Vision》2010,90(1):45-61
Color is a powerful visual cue in many computer vision applications such as image segmentation and object recognition. However,
most of the existing color models depend on the imaging conditions that negatively affect the performance of the task at hand.
Often, a reflection model (e.g., Lambertian or dichromatic reflectance) is used to derive color invariant models. However,
this approach may be too restricted to model real-world scenes in which different reflectance mechanisms can hold simultaneously. 相似文献
6.
The paper describes results of a longitudinal study of developments in the area of software product and process quality improvement within a Hungarian software company, IQSOFT Ltd. This company has been active in this area since 1993, trying to build, introduce and maintain an efficiently working quality management system which, e.g., fulfils the ISO 9001 requirements, allows steady software process improvement and, at the same time, conforms to company's own needs. Over the last eight years five phases could be distinguished. Each phase is described shortly, following the same structure, namely: basic starting points, key problem areas, literature consulted, activities and design executed, reflections on what happened and why. The lessons resulting from the analysis of this case have been formulated in terms of guidelines. We feel that these are applicable to any low maturity software development organisation embarking on a product or process quality improvement endeavour. These guidelines are developed around a framework containing the basic issues of software production (project management, technical processes and products). The guidelines advocate a careful step-by-step development of definitions, quality characteristics, and metrics related to these objects while at the same time developing and introducing the associated process. 相似文献
7.
Does the immersive design of an educational gaming environment affect learners’ virtual presence and how much do they learn? Does virtual presence affect learning? This study tries to answer these questions by examining the differences in virtual presence and learning outcomes in two different computer-based multimedia environments: a gaming environment with high immersive design vs. hypertext learning environment with low immersive design. As the main focus, the effect of virtual presence on learning is also explained and tested. By identifying virtual presence as a variable that may determine learning, it is argued that computer gaming environments present a new challenge for researchers to investigate, particularly, the effects of virtual presence on the immersive design of games in order to help designers to predict which instructional configurations will maximize learning performance. In general, results revealed that the high-immersive gaming environment leads to the strongest form of virtual presence but also decreased learning. Although regression analyses indicate that virtual presence positively influences trivial- and non-trivial learning outcomes, learners who learned in a low-immersive environment outperformed the gaming group. A mediation analysis showed that the relation between virtual presence and non-trivial learning outcomes is partly mediated through increased cognitive load. 相似文献
8.
Engineer Bainomugisha Jorge Vallejos Elisa Gonzalez Boix Pascal Costanza Theo D'Hondt Wolfgang De Meuter 《Software》2012,42(3):331-356
The iPhone SDK provides a powerful platform for the development of applications that make use of iPhone capabilities, such as sensors, GPS, Wi‐Fi, or Bluetooth connectivity. We observe that so far the development of iPhone applications has mostly been restricted to using Objective‐C. However, developing applications in plain Objective‐C on the iPhone OS suffers from limitations, such as the need for explicit memory management and lack of syntactic extension mechanism. Moreover, when developing distributed applications in Objective‐C, programmers have to manually deal with distribution concerns, such as service discovery, remote communication, and failure handling. In this paper, we discuss our experience in porting the Scheme programming language to the iPhone OS and how it can be used together with Objective‐C to develop iPhone applications. To support the interaction between Scheme programs and the underlying iPhone APIs, we have implemented a language symbiosis layer that enables programmers to access the iPhone SDK libraries from Scheme. In addition, we have designed high‐level distribution constructs to ease the development of distributed iPhone applications in an event‐driven style. We validate and discuss these constructs with a series of examples, including an iPod controller, a maps application, and a distributed multiplayer Scrabble‐like game. We discuss the lessons learned from this experience for other programming language ports to mobile platforms. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
9.
Together with the development of information systems research, there has also been increased interest in non-linear relationships between focal constructs. This article presents six Partial Least Squares-based approaches for estimating formative constructs’ quadratic effects. In addition, these approaches’ performance is tested by means of a complex Monte Carlo experiment. The experiment reveals significant and substantial differences between the approaches. In general, the performance of the hybrid approach as suggested by Wold (1982) is most convincing in terms of point estimate accuracy, statistical power, and prediction accuracy. The two-stage approach suggested by Chin et al (1996) showed almost the same performance; differences between it and the hybrid approach – although statistically significant – were unsubstantial. Based on these results, the article provides guidelines for the analysis of non-linear effects by means of variance-based structural equation modelling. 相似文献
10.
J. Theo Kloprogge Maarten Broekmans Loc V. Duong Wayde N. Martens Liesel Hickey Ray L. Frost 《Journal of Materials Science》2006,41(11):3535-3539
Lecontite, (NH4)Na(SO4).2H2O, was synthesised at room temperature in high purity compared to earlier work with a minor impurity of mascagnite, (NH4)2SO4. Rietveld refinement of the XRD results confirmed the crystal structure and unit cell dimensions as published earlier. Raman
and Infrared spectroscopy, in conjunction with factor group analysis, resulted in a complex pattern of overlapping sulphate,
NH and OH modes. The NH modes υ1 was observed around 2880 cm−1, υ2 around 1700 cm−1 overlapping with water OH-bending modes, υ3 around 3300 cm−1 overlapping with water OH-stretching modes around 3023, 3185 and 3422 cm−1, and υ4 around 1432, 1447 and 1462 cm−1. The sulphate group in the crystal structure displays a decrease in symmetry from Td as evidenced by the activation of the ν1 mode at 982 cm−1 and the ν2 mode around 452 cm−1 in the Infrared spectrum. The υ3 mode shows clear splitting in the infrared spectra with a strong band at 1064 cm−1 accompanied by two shoulders at 1107 and 1139 cm−1. The Raman spectra show three weak bands at 1068, 1109 and 1135 cm−1 with a shoulder at 1155 cm−1. Similar splitting was observed for the υ4 mode around 611 and 632 cm−1 in the Infrared and Raman spectra, respectively. 相似文献