全文获取类型
收费全文 | 603篇 |
免费 | 12篇 |
专业分类
电工技术 | 32篇 |
综合类 | 2篇 |
化学工业 | 249篇 |
金属工艺 | 12篇 |
机械仪表 | 12篇 |
建筑科学 | 3篇 |
能源动力 | 21篇 |
轻工业 | 17篇 |
水利工程 | 1篇 |
无线电 | 44篇 |
一般工业技术 | 112篇 |
冶金工业 | 60篇 |
原子能技术 | 20篇 |
自动化技术 | 30篇 |
出版年
2023年 | 3篇 |
2022年 | 13篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 20篇 |
2013年 | 28篇 |
2012年 | 21篇 |
2011年 | 35篇 |
2010年 | 22篇 |
2009年 | 30篇 |
2008年 | 29篇 |
2007年 | 21篇 |
2006年 | 22篇 |
2005年 | 32篇 |
2004年 | 14篇 |
2003年 | 22篇 |
2002年 | 20篇 |
2001年 | 10篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1998年 | 36篇 |
1997年 | 20篇 |
1996年 | 15篇 |
1995年 | 4篇 |
1994年 | 12篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 13篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1966年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有615条查询结果,搜索用时 31 毫秒
41.
We study the problem of approximating the family of hard-decision frequency-shift keying demodulated correlated flat Rician fading channels via a recently introduced queue-based channel (QBC) model for binary communication channels with memory. For a given ldquodiscretizedrdquo fading channel, we construct a QBC whose noise process is statistically ldquocloserdquo in the Kullback-Leibler sense to the error or noise process that is generated by the fading channel, and the modeling accuracy is evaluated in terms of noise autocorrelation function (ACF) and channel capacity. Numerical results indicate that the QBC provides a good approximation of the fading channels for a wide range of channel conditions. Furthermore, it estimates the noise ACF more accurately than the finite-state Markov models that have been recently studied by Pimentel , while, at the same time, remaining mathematically tractable. 相似文献
42.
Yasuhiko Otsuki Toshihisa Kajiwara Kazumori Funatsu 《Polymer Engineering and Science》1997,37(7):1171-1181
Numerical viscoelastic simulations were carried out using a K-BKZ type of separable integral constitutive equation. Both reversible and irreversible models were tried for several types of damping functions to calculate the annular extrudate behavior of high-density polyethylene (HDPE). There are two aims in this study; first, to clarify the properties of these dumping functions, and second, to investigate the influence of rheological characteristics on annular extrudate swell. In these numerical simulations, relaxation spectrum and shear viscosity were fixed, and the other characteristics were varied. The reversional response of the damping function mainly has an effect on the magnitude of the area swell even if the die is straight. The irreversible model expresses the experimental results of annular extrudate swell better than the reversible model. The accurate fitting of N1 by the damping model is important for predicting it. The magnitude of N1 predicted from the Wagner exponential model is lower than that of the PSM model, and the area swell shows the same tendency as N1. A modified PSM model that allows the N1 curve to shift can fit the magnitude of area swell. The relationship between the diameter and thickness of the extrudate depends on N2/N1, and it was estimated by simple linear elasticity of solids. The time dependent viscosity varies with the type of damping function, and it influences the time-dependent swell. 相似文献
43.
44.
Pradyumna Gupta Himanshu Jain David B. Williams Tsuyoshi Honma Yasuhiko Benino Takayuki Komatsu 《Journal of the American Ceramic Society》2008,91(1):110-114
Using a novel, selective heating by Nd:YAG laser, a single-crystal architecture is created in a model glass system, Sm0.5 La0.5 BGeO5 , which devitrifies congruently into a ferroelectric phase of the same composition as the parent glass. The Sm3+ ions in glass absorb the light and heat the matrix locally resulting in devitrification. Initially, a polycrystalline spot is formed. However, with optimum laser power, scanning speed, and the depth of focus, one of the grains acts as the seed for further growth as a single crystal. By programming the relative displacement of the glass with respect to laser spot, desired single ferroelectric crystal architecture is created. The optical functionalities (guiding of light and second harmonic generation) of the architectures are shown, which demonstrate the viability of this method for constructing active elements in optical integrated circuits. The single-crystal nature of the architecture is confirmed from the electron backscattered diffraction results. 相似文献
45.
Tamio Iida Yasuhiko Takamido Shunsuke Ogawa Tomoki Narita Takashi Itoh 《Thin solid films》2008,516(5):807-809
TiO2 thin films prepared by Hot-Wire CVD method have been studied as a protecting material of transparent conducting oxide (TCO) against atomic hydrogen exposures for the fabrications of Si thin film solar cells. It was found that electrical conductivity of the films at room temperature reached a value of 0.4 S/cm. This value is 2-3 orders of magnitude higher than that of TiO2 films prepared by RF magnetron sputtering and electron-beam evaporation methods in our previous works. The conductivity improvement seems to be partly due to the enlargement of TiO2 crystallites. 相似文献
46.
Yasuyuki Koyama Ryuzo Takagi Yasuhiko Iwadate Kazuko Fukushima 《Journal of Alloys and Compounds》1997,260(1-2):75-79
A phase diagram of the EuCl2---NaCl system was determined by differential scanning calorimetry (DSC) and the activity coefficients of EuCl2 and NaCl in this system were estimated under some assumptions. According to DSC measurement, it was found that there were two phase transitions at 1123.9 K and 1016.8 K. In order to specify the melting point of EuCl2 we did Raman spectroscopy experiments. Thus, the melting point of EuCl2 was evaluated to be 1016.8 K which was detected as the lower peak in the DSC curve. Raman spectroscopy of this system suggested that complex species were not formed clearly in the EuCl2 poor system and the estimated activity coefficients of EuCl2 also supported this suggestion. 相似文献
47.
Takeshi Takahashi Kyosuke Kojima Wei Zhang Kanae Sasaki Masaru Ito Hironori Suzuki Masato Kawasaki Soichi Wakatsuki Terunao Takahara Hideki Shibata Masatoshi Maki 《International journal of molecular sciences》2015,16(2):3677-3699
ALG-2, a 22-kDa penta-EF-hand protein, is involved in cell death, signal transduction, membrane trafficking, etc., by interacting with various proteins in mammalian cells in a Ca2+-dependent manner. Most known ALG-2-interacting proteins contain proline-rich regions in which either PPYPXnYP (type 1 motif) or PXPGF (type 2 motif) is commonly found. Previous X-ray crystal structural analysis of the complex between ALG-2 and an ALIX peptide revealed that the peptide binds to the two hydrophobic pockets. In the present study, we resolved the crystal structure of the complex between ALG-2 and a peptide of Sec31A (outer shell component of coat complex II, COPII; containing the type 2 motif) and found that the peptide binds to the third hydrophobic pocket (Pocket 3). While amino acid substitution of Phe85, a Pocket 3 residue, with Ala abrogated the interaction with Sec31A, it did not affect the interaction with ALIX. On the other hand, amino acid substitution of Tyr180, a Pocket 1 residue, with Ala caused loss of binding to ALIX, but maintained binding to Sec31A. We conclude that ALG-2 recognizes two types of motifs at different hydrophobic surfaces. Furthermore, based on the results of serial mutational analysis of the ALG-2-binding sites in Sec31A, the type 2 motif was newly defined. 相似文献
48.
Liposome‐Based in Vitro Evolution of Aminoacyl‐tRNA Synthetase for Enhanced Pyrrolysine Derivative Incorporation
下载免费PDF全文
![点击此处可从《Chembiochem : a European journal of chemical biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Atsuko Uyeda Dr. Takayoshi Watanabe Dr. Yasuhiko Kato Prof. Hajime Watanabe Prof. Tetsuya Yomo Prof. Takahiro Hohsaka Dr. Tomoaki Matsuura 《Chembiochem : a European journal of chemical biology》2015,16(12):1797-1802
Methanosarcina species pyrrolysyl‐tRNA synthetase (PylRS) attaches Pyl to its cognate amber suppressor tRNA. The introduction of two mutations (Y384F and Y306A) into PylRS was previously shown to generate a mutant, designated LysZ‐RS, that was able to attach N‐benzyloxycarbonyl‐L ‐lysine (LysZ) to its cognate tRNA. Despite the potential of LysZ derivatives, further LysZ‐RS engineering has not been performed; consequently, we aimed to generate LysZ‐RS mutants with improved LysZ incorporation activity through in vitro directed evolution. Using a liposome‐based in vitro compartmentalization (IVC) approach, we screened a randomly mutagenized gene library of LysZ‐RS and obtained a mutant that showed increased LysZ incorporation activity both in vitro and in vivo. The ease and high flexibility of liposome‐based IVC should enable the evolution of not only LysZ‐RS that can attach various LysZ derivatives but also of other enzymes involved in protein translation. 相似文献
49.
Hideyuki Nakano Toru Takahashi Takahiro Tanino Yasuhiko Shirota 《Dyes and Pigments》2010,84(1):102-107
Novel azobenzene-based photo-responsive amorphous molecular materials, 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-cyanoazobenzene and 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-nitroazobenzene, have been synthesized and the formation of surface relief grating on their amorphous films has been investigated. It was found that a relatively large surface relief grating could be inscribed on both amorphous films upon interference exposure to the writing laser beams. The modulation depth of the surface relief grating inscribed on the amorphous film of the cyano-substituted material was found to be larger than that inscribed on the film of the nitro-substituted one and seemed to be comparable to that inscribed on the amorphous film of the parent material, 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene. These results were discussed from the viewpoint of their trans–cis photoisomerizations as amorphous films and glass-transition temperatures. 相似文献
50.
Mizuki Tsuta Yasuhiko Sasaki Ikuo Takeuchi Hideki Nakamoto Jun Ishikawa Susumu Kawasaki Junichi Sugiyama Kaori Fujita Masatoshi Yoshimura Mario Shibata Mito Kokawa 《LWT》2014
Flow cytometry (FCM) and aerobic plate count (APC) by the culture method were performed on green tea samples spiked with Escherichia coli type strain NCTC9001 (ATCC11775) solutions of different concentrations. In FCM, fluorescence signals from multiple stained bacteria and other fluorophores are detected using detector channels, and recorded as events with a voltage at each channel. FCM data were analyzed in two ways: conventional and multivariate analysis. In the former, the number of events with voltages larger than the defined threshold values was regarded as the predicted APC. In the latter, voltage histograms of all channels were obtained and merged horizontally to serve as explanatory variables. Then a partial least squares regression (PLSR) model was built to predict APC from the histogram data. The coefficient of determination (R2) and the root mean square error (RMSE) between APC by the culture method and that predicted by conventional FCM were 0.916 and 1.08 cfu/ml2. The APC values predicted by the PLSR model and those measured were in good agreement with R2 of 0.982 and RMSE of 0.417 cfu/ml, which verified the potential of the proposed method for improving APC prediction accuracy by FCM. 相似文献