全文获取类型
收费全文 | 5730篇 |
免费 | 246篇 |
国内免费 | 25篇 |
专业分类
电工技术 | 71篇 |
综合类 | 21篇 |
化学工业 | 1417篇 |
金属工艺 | 126篇 |
机械仪表 | 130篇 |
建筑科学 | 172篇 |
矿业工程 | 45篇 |
能源动力 | 223篇 |
轻工业 | 640篇 |
水利工程 | 55篇 |
石油天然气 | 32篇 |
武器工业 | 2篇 |
无线电 | 530篇 |
一般工业技术 | 732篇 |
冶金工业 | 964篇 |
原子能技术 | 50篇 |
自动化技术 | 791篇 |
出版年
2023年 | 52篇 |
2022年 | 157篇 |
2021年 | 225篇 |
2020年 | 143篇 |
2019年 | 113篇 |
2018年 | 157篇 |
2017年 | 141篇 |
2016年 | 151篇 |
2015年 | 136篇 |
2014年 | 210篇 |
2013年 | 343篇 |
2012年 | 286篇 |
2011年 | 323篇 |
2010年 | 258篇 |
2009年 | 239篇 |
2008年 | 258篇 |
2007年 | 241篇 |
2006年 | 176篇 |
2005年 | 160篇 |
2004年 | 132篇 |
2003年 | 133篇 |
2002年 | 125篇 |
2001年 | 100篇 |
2000年 | 85篇 |
1999年 | 80篇 |
1998年 | 265篇 |
1997年 | 178篇 |
1996年 | 155篇 |
1995年 | 109篇 |
1994年 | 76篇 |
1993年 | 94篇 |
1992年 | 43篇 |
1991年 | 51篇 |
1990年 | 34篇 |
1989年 | 36篇 |
1988年 | 29篇 |
1987年 | 31篇 |
1986年 | 29篇 |
1985年 | 39篇 |
1984年 | 24篇 |
1983年 | 25篇 |
1982年 | 27篇 |
1981年 | 23篇 |
1980年 | 24篇 |
1979年 | 25篇 |
1978年 | 16篇 |
1977年 | 33篇 |
1976年 | 33篇 |
1972年 | 14篇 |
1943年 | 23篇 |
排序方式: 共有6001条查询结果,搜索用时 9 毫秒
61.
Fengshuo Hu John J. La Scala Santosh Kumar Yadav James Throckmorton Giuseppe R. Palmese 《应用聚合物科学杂志》2021,138(24):50579
A series of bio-rubber (BR) tougheners for thermosetting epoxy resins was prepared by grafting renewable fatty acids with different chain lengths onto epoxidized soybean oil at varying molar ratios. BR-toughened samples were prepared by blending BRs with diglycidyl ether of bisphenol A resins, Epon 828 and Epon 1001F, at different weight fractions and stoichiometrically cured using an amine curing agent, 4, 4′-methylene biscyclohexanamine (PACM). Fracture toughness properties of the unmodified and BR toughened polymer samples—including critical strain energy release rate (GIc), and critical stress intensity factor (KIc)—were measured to investigate the toughening effect of prepared BRs. It was found that the degree of phase separation and toughening were more controllable relative to similar polymers cured using the aromatic curing agent Epikure W, and the use of higher molecular epoxy resins produces a synergistic effect increasing the toughness much more than similar polymers made with lower molecular weight epoxy resins. Average BR domain sizes ranging from 200 to 900 nm were observed, and formulations with GIc, values KIc as high as 1.0 kJ/m2 and 1.4 MPa m1/2 were attained respectively for epoxy systems with Tg greater than 130°C. 相似文献
62.
Fengshuo Hu Santosh Kumar Yadav John J. La Scala James Throckmorton Giuseppe R. Palmese 《应用聚合物科学杂志》2021,138(24):50570
A series of bio-rubber (BR) reactive tougheners for thermosetting epoxy resins was prepared by grafting renewable saturated fatty acids of different chain lengths (C6-C14) onto epoxidized soybean oil (ESO) at varying molar ratios. The tunable nature of the BR systems derives from the architecture and functionality of naturally occurring molecules. Control of BR reactivity and molecular weight by varying the degree of grafting and the chain length of the fatty acid was demonstrated. The BR-toughened samples were prepared by blending BRs with diglycidyl ether of bisphenol A (DGEBA), Epon 828, and stoichiometrically curing the mixture using an aromatic amine hardener, diethyl toluene diamine (Epikure W). Fracture surface morphology studies showed that tuning of phase separated particle sizes was possible depending on the BR type and weight fraction. The resulting toughening effect was evaluated by measuring the fracture toughness of control and toughened polymer samples. The use of BRs significantly improved the critical strain energy release rate and critical stress intensity factor values of thermosetting polymer samples without significantly reducing Tg and modulus. In addition to toughening and adding renewable content to petroleum-based thermosetting epoxy systems these new tougheners have low viscosity compared to common alternatives and aid ease of processing. 相似文献
63.
Caroline Cagnin Bruno Matheus Simões Fábio Yamashita Gizilene Maria de Carvalho Maria Victória Eiras Grossmann 《Polymer Engineering and Science》2021,61(2):388-396
This work aims to develop hydrogel films of starch and carboxymethyl cellulose (CMC) crosslinked with sodium trimetaphosphate (STMP) and to characterize some of their properties. Starch and STMP (S/T), starch and CMC (S/C), and mixed (S/T/C) films were prepared by casting. The degree of substitution, morphology, swelling degree, FTIR, mechanical properties, and sorption isotherms were studied. Reticulated samples (S/T and S/T/C) showed the same degree of substitution (0.050 ± 0.001). All films presented homogeneous morphology, but the mixed film showed greater roughness. Crosslinking increased the swelling capacity of the mixed hydrogel at pH 7, although it remained decreased concerning the S/T hydrogel. However, this property was sensitive to pH variations. The mixed film (S/T/C) showed greater mechanical resistance. The casting process was efficient to produce hydrogel films of starch/CMC crosslinked with STMP and the general results demonstrated the advantages of the mixed hydrogel. 相似文献
64.
65.
66.
Expert finding is an information retrieval task that is concerned with the search for the most knowledgeable people with respect to a specific topic, and the search is based on documents that describe people's activities. The task involves taking a user query as input and returning a list of people who are sorted by their level of expertise with respect to the user query. Despite recent interest in the area, the current state‐of‐the‐art techniques lack in principled approaches for optimally combining different sources of evidence. This article proposes two frameworks for combining multiple estimators of expertise. These estimators are derived from textual contents, from graph‐structure of the citation patterns for the community of experts and from profile information about the experts. More specifically, this article explores the use of supervised learning to rank methods, as well as rank aggregation approaches, for combining all of the estimators of expertise. Several supervised learning algorithms, which are representative of the pointwise, pairwise and listwise approaches, were tested, and various state‐of‐the‐art data fusion techniques were also explored for the rank aggregation framework. Experiments that were performed on a dataset of academic publications from the Computer Science domain attest the adequacy of the proposed approaches. 相似文献
67.
68.
69.
Fouzhan Hosseini Amir Fijany Saeed Safari Jean-Guy Fontaine 《Journal of Real-Time Image Processing》2013,8(4):421-435
In this paper, we present faster than real-time implementation of a class of dense stereo vision algorithms on a low-power massively parallel SIMD architecture, the CSX700. With two cores, each with 96 Processing Elements, this SIMD architecture provides a peak computation power of 96 GFLOPS while consuming only 9 Watts, making it an excellent candidate for embedded computing applications. Exploiting full features of this architecture, we have developed schemes for an efficient parallel implementation with minimum of overhead. For the sum of squared differences (SSD) algorithm and for VGA (640 × 480) images with disparity ranges of 16 and 32, we achieve a performance of 179 and 94 frames per second (fps), respectively. For the HDTV (1,280 × 720) images with disparity ranges of 16 and 32, we achieve a performance of 67 and 35 fps, respectively. We have also implemented more accurate, and hence more computationally expensive variants of the SSD, and for most cases, particularly for VGA images, we have achieved faster than real-time performance. Our results clearly demonstrate that, by developing careful parallelization schemes, the CSX architecture can provide excellent performance and flexibility for various embedded vision applications. 相似文献
70.
Fuzzy c-means (FCMs) is an important and popular unsupervised partitioning algorithm used in several application domains such as pattern recognition, machine learning and data mining. Although the FCM has shown good performance in detecting clusters, the membership values for each individual computed to each of the clusters cannot indicate how well the individuals are classified. In this paper, a new approach to handle the memberships based on the inherent information in each feature is presented. The algorithm produces a membership matrix for each individual, the membership values are between zero and one and measure the similarity of this individual to the center of each cluster according to each feature. These values can change at each iteration of the algorithm and they are different from one feature to another and from one cluster to another in order to increase the performance of the fuzzy c-means clustering algorithm. To obtain a fuzzy partition by class of the input data set, a way to compute the class membership values is also proposed in this work. Experiments with synthetic and real data sets show that the proposed approach produces good quality of clustering. 相似文献