全文获取类型
收费全文 | 755篇 |
免费 | 56篇 |
国内免费 | 28篇 |
专业分类
电工技术 | 60篇 |
综合类 | 19篇 |
化学工业 | 201篇 |
金属工艺 | 31篇 |
机械仪表 | 44篇 |
建筑科学 | 11篇 |
矿业工程 | 2篇 |
能源动力 | 25篇 |
轻工业 | 78篇 |
水利工程 | 7篇 |
石油天然气 | 9篇 |
无线电 | 76篇 |
一般工业技术 | 134篇 |
冶金工业 | 15篇 |
原子能技术 | 31篇 |
自动化技术 | 96篇 |
出版年
2023年 | 2篇 |
2022年 | 14篇 |
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 19篇 |
2018年 | 33篇 |
2017年 | 20篇 |
2016年 | 26篇 |
2015年 | 24篇 |
2014年 | 25篇 |
2013年 | 64篇 |
2012年 | 45篇 |
2011年 | 45篇 |
2010年 | 33篇 |
2009年 | 44篇 |
2008年 | 52篇 |
2007年 | 26篇 |
2006年 | 36篇 |
2005年 | 44篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 18篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1976年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1932年 | 2篇 |
排序方式: 共有839条查询结果,搜索用时 15 毫秒
831.
Kuypers JH Tanaka S Esashi M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2011,58(2):406-413
We have developed a wafer-level packaging solution for surface acoustic wave devices using imprinted dry film resist (DFR). The packaging process involves the preparation of an imprinted dry film resist that is aligned and laminated to the device wafer and requires one additional lithography step to define the package outline. Two commercial dry film solutions, SU-8 and TMMF, have been evaluated. Compared with traditional ceramic packages, no detectable RF parasitics are introduced by this packaging process. At the same time, the miniature package dimensions allow for wafer-level probing. The packaging process has the great advantage that the cavity formation does not require any sacrificial layer and no liquids, and therefore prevents contamination or stiction of the packaged device. This non-hermetic packaging process is ideal for passive antenna modules using polymer technology for low-cost SAW identification (ID)-tags or lidding in low-temperature cofired ceramic (LTCC) antenna substrates for high-performance wireless sensors. This technique is also applicable to SAW filters and duplexers for module integration in cellular phones using flip-chip mounting and hermetic overcoating. 相似文献
832.
针对数控车削加工中非圆曲线回转面的复杂外形零件,其编程难度大,加工轮廓不易控制的特点,采用宏程序编程方法的变量算术和逻辑运算功能以及转移、循环功能,编制复杂轮廓零件的加工程序。运用CAXA数控车削自动编程软件的零件建模、刀具路径生成、后置代码生成和模拟仿真加工验证功能,完成了复杂轮廓零件加工的自动编程。实践表明,宏程序编程灵活、精炼,修订方便,适应性强,简化了程序。CAXA数控车削自动编程简化了复杂曲面零件手工编程时繁琐的节点计算和指令的逐一输入工作,大大提高了加工效率。 相似文献
833.
目的 针对局部梯度编码算子(LGC)只能在固定大小邻域内提取图像纹理特征的不足,提出了一种非对称邻域LGC算子(AR-LGC)多尺度融合的表情特征提取方法。方法 首先,对归一化的表情图像进行Gauss滤波处理;然后,对图像进行分块,对每个子块图像中每一像素点,采用不同邻域大小的AR-LGC算子得到两个二进制序列,将两个序列作按位逻辑异或得到一个新的序列,对此序列进行编码,计算每个子块的直方图分布,级联各子块直方图构成人脸表情的特征;最后用SVM分类器进行表情分类识别。结果 该算法在JAFFE库和CK库上进行实验,分别取得了95.24%和96.83%的平均识别率,并与CBP(中心化二值模式)、LBP(局部二值模式)、LGC和AR-LBP(非对称局部二值模式)算法进行了比较,在JAFFE库的平均识别率分别比CBP、LBP、LGC、AR-LBP高5.6%、4.85%、3.71%、2.40%,在CK库的平均识别率分别比CBP、LBP、LGC、AR-LBP高3.66%、2.50%、2.17%、1.66%,实验结果表明,该算法可以较准确地进行人脸表情识别。结论 本文所提的表情特征提取方法通过融合不同梯度不同尺度子邻域间的强度关系,可以很好地表达图像的局部特征和全局特征,与典型的特征提取算法的对比实验也表明了本文算法的有效性,表明本文算法适用于静态人脸表情图像的识别。 相似文献
834.
Hirokatsu Umegami Kazuhiro Umetani Masayoshi Yamamoto Eiji Hiraki 《IEEJ Transactions on Electrical and Electronic Engineering》2015,10(Z1):S168-S170
Electric‐field coupling wireless power transfer has been commonly analyzed using the circuit model. However, the circuit behavior of this model is not necessarily apparent because their resonant modes can be far complicated than the basic LC oscillation. This issue is addressed in this paper by proposing a novel equivalent circuit for a basic wireless power transfer system. This equivalent circuit has a simpler topology than the conventional circuit model. Furthermore, the equivalent circuit allows intuitive understanding of three types of the resonant modes. Along with theoretical derivation of the proposed equivalent circuit, this paper also presents simulation results, which verified the appropriateness of the equivalent circuit. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
835.
Kenji Saito Tsuyoshi Ito Takashi Kuribayashi Kazumi Mochida Teruo Nakakuki Masaru Shibata Masayoshi Sugawara 《Starch - St?rke》2001,53(9):424-430
Resistant starch content of high‐amylose corn starch (HAS) was doubled by heat‐moisture treatment. Resistant starch content of HAS and heat‐moisture treated high‐amylose corn starch (HMT‐HAS) were 31.8 and 67.3%, respectively, as determined by enzymatic‐gravimetric method. Effects of the two types of high‐amylose corn starches, HAS and HMT‐HAS, on starch fermentation, microflora, pH, short chain fatty acid (SCFA) content and β‐glucuronidase activity in the cecal content have been investigated. Rats were given ordinary corn starch (OCS; control), HAS or HMT‐HAS at 10% level for 10 13 days. The cecal and colorectal content s weights were larger in HAS and HMT‐HAS groups than in the OCS group. The cecal content s weight did not differ between HAS and HMT‐HAS groups, while the colorectal content s weight was higher in the HMT‐HAS group than in the HAS group. The upper and lower small intestinal and cecal starch contents were significantly higher in the HAS and HMT‐HAS groups than in the OCS group, whereas there were no differences between colorectal starch content in group OCS and HAS. Starch excretion in feces was significantly higher in groups HAS and HMT‐HAS than in group OCS, the increase in the HMT‐HAS group was especially remarkable. The composition of the cecal microflora was not effected by the diet. β‐Glucuronidase activities in rats fed HAS or HMT‐HAS decreased. SCFA concentration was higher in groups HAS and HMT‐HAS than in group OCS, and the cecal pH was lower in groups HAS and HMT‐HAS than in group OCS. 相似文献
836.
Mamoru Sasaki Jun Imaoka Masayoshi Yamamoto Akira Nakano Koji Fuse 《Electrical Engineering in Japan》2023,216(2):e23439
A multiphase DC-DC converter consisting of a coupled inductor and fast switching devices enables power electronics equipment to achieve a high-power density. However, with such devices, the fast voltage transition generates substantial common mode (CM) noise. However, there are very few studies on CM noise reduction for multiphase converters using a coupled inductor. Therefore, in this paper, a CM noise reduction method is proposed for a multiphase DC-DC converter that hardly lowers the power density. 相似文献
837.
Masato Sasaki Hirokatsu Umegami Masayoshi Yamamoto 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(Z2):S144-S145
Silicon carbide schottky barrier diodes (SiC SBDs) have much better characteristic than Si PiN diode in high voltage applications because SiC SBDs do not have recovery effect. However, simple replacing is not the most effective way. In a boost converter, the power loss caused by the SiC SBD can be divided into the conduction loss of the SiC SBD and the loss caused by the energy stored in the junction capacitance of the SiC SBD. Therefore analysis of not only the conduction loss but also the loss caused by the energy stored in the junction capacitance of the SiC SBD can realize the SiC SBD selection to improve the efficiency of the boost converter. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
838.
Xin Kang Fuji Ren Yunong Wu 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(6):768-775
Learning emotions from texts has been an active research topic in affective computing. However, the lack of reliable connection between emotions and language features has caused severely biased emotion predictions. Moreover, the author‐specific patterns in emotion expression could potentially affect emotion predictions, which has never been studied. In this paper, we propose a semisupervised learning algorithm to learn emotional features from large‐scaled micro‐blog documents with a Bayesian network, and introduce an emotion transition factor to generate the author‐specific emotion predictions. We infer the author‐specific emotions in micro‐blog streams through belief propagation, and learn the emotional features through an expectation maximization estimation procedure. We report results of single‐label and multilabel emotion predictions on a micro‐blog stream corpus, and analyze the improvements achieved by the semisupervised feature learning strategy and the incorporation of emotion transition patterns. Finally, we perform personality analysis based on the authors' emotion distribution and examine emotion distributions in the learned features. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
839.
The effect of lubricants on deep drawability was studied for two types of zinc-coated steel sheets on a high-speed deep-drawing machine. The drawability of galvannealed steel sheet, GA, at low speeds is significantly improved by friction modifiers, due to reduction in frictional forces around the die radius. In contrast to the results for GA, double layered steel, GAE, which has an Fe-rich alloy coating on the top, and is superior to GA in terms of drawability, is insensitive to changes in the additives. This is mainly because the hardness of the upper coating layer of GAE decreases frictional resistance through a decline in the boundary contact area. 相似文献