全文获取类型
收费全文 | 919篇 |
免费 | 31篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 93篇 |
化学工业 | 260篇 |
金属工艺 | 22篇 |
机械仪表 | 17篇 |
建筑科学 | 9篇 |
能源动力 | 39篇 |
轻工业 | 82篇 |
水利工程 | 1篇 |
无线电 | 60篇 |
一般工业技术 | 176篇 |
冶金工业 | 121篇 |
原子能技术 | 20篇 |
自动化技术 | 51篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 11篇 |
2017年 | 17篇 |
2016年 | 31篇 |
2015年 | 12篇 |
2014年 | 26篇 |
2013年 | 45篇 |
2012年 | 36篇 |
2011年 | 63篇 |
2010年 | 37篇 |
2009年 | 38篇 |
2008年 | 51篇 |
2007年 | 38篇 |
2006年 | 32篇 |
2005年 | 23篇 |
2004年 | 23篇 |
2003年 | 33篇 |
2002年 | 31篇 |
2001年 | 16篇 |
2000年 | 19篇 |
1999年 | 15篇 |
1998年 | 58篇 |
1997年 | 46篇 |
1996年 | 26篇 |
1995年 | 17篇 |
1994年 | 18篇 |
1993年 | 15篇 |
1992年 | 8篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 6篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有951条查询结果,搜索用时 15 毫秒
51.
Oki SekizawaTakuya Hasegawa Naoto KitamuraYasushi Idemoto 《Journal of power sources》2011,196(16):6651-6656
We investigated effects of delithiation on crystal, electronic structure, thermodynamic stability and physical property of LixNi0.5Mn0.5O2 by using a chemical delithiation treatment with ammonium peroxodisulfate, and compared the results with those of electrochemical delithiation. X-ray diffraction and thermodynamic data indicated that there was no phase transition in the samples after the chemical delithiation treatment within the lithium range of 0.50 ≤ x ≤ 1.00. From the ICP measurements and potentiometric titration, it was found that the chemical treatment successfully remove Li from the structure without any elution of Ni and Mn, but it accompanied O2 removal at an initial process of the delithiation, i.e. 0.80 ≤ x ≤ 1.00. Crystal and electronic structure analyses also suggested such a O2 removal at the lithium content range in the chemical delithiation method, although the estimated structure changes below x = 0.80 showed similar tendencies to those by the electrochemical delithiation. 相似文献
52.
Measurement of the flood discharge of a small-sized river using an existing digital video recording system 总被引:1,自引:0,他引:1
In this study, a closed-circuit television (CCTV) system, installed for surveillance purposes, is utilized to measure the flow rate during a flood. The procedure to determine both the angle and scale-factor of the camera is described. Then, image analysis techniques, namely the direct visual measurement method, Large-Scale PIV (LSPIV) and Space-Time Image Velocimetry (STIV), are applied to the video images recorded by the CCTV camera. The results of these methods and the conventional float measurement are compared. In addition, the accuracy of the respective methods is discussed. A set of low-quality video images of a flood during a thunderstorm that occurred under the dark ambient conditions (midnight) is analyzed using three image-based methods. The transition of the flow rate during the event is successfully estimated. 相似文献
53.
Sadamasu K Tabei Y Shinkai T Hasegawa M Kaneko S Hirai A Nakama A Ishizaki N Odagiri M Kamata S Yano K Kai A Morozumi S 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2006,47(1):1-8
A PCR method for the effective detection of Coxiella burnetii in commercially available mayonnaise was developed. Sample preparations were isolated from 50 g portions of each mayonnaise product by four successive extraction steps in phosphate buffer with 2.0 M NaCl. These extracts were then centrifuged at 20,000 x g for 60 min. DNA was isolated from the solution containing the precipitate with a commercial kit, and amplified quantitatively using real-time PCR that targeted the com1 region of C. burnetii. The recoveries of C. burnetii from 2 kinds of commercial mayonnaise specimens, with a baseline control of 1 x 10(7) particles of the Nine Mile phase II strain, were 85.0 +/- 6.0% and 72.0 +/- 0.4%, respectively. The determination limit of this method was 500 C. burnetii particles per 50 g of mayonnaise. The DNA specimens isolated from 50 different commercial mayonnaise samples sold in Tokyo using this method were amplified using both nested PCR and real-time PCR. No contamination by C. burnetii was detected in any of the mayonnaise samples. 相似文献
54.
Development and characterization of a photoautotrophic cell line of pak-bung hairy roots 总被引:1,自引:0,他引:1
Nagatome H Tsutsumi M Kino-Oka M Taya M 《Journal of Bioscience and Bioengineering》2000,89(2):151-156
A cell line of photoautotrophic pak-bung hairy roots was established from photomixotrophic ones by acclimation cultivations with a stepwise change of sucrose concentration in a medium with 3.0% CO2-enriched air supplied under continuous light irradiation. The derived photoautotrophic hairy roots had high chlorophyll content and activity of 1,5-ribulose-bisphosphate carboxylase/oxygenase, the values of which were 4.1- and 2.0-fold more than those of the parent photomixotroph, respectively. Electron microscopic observation revealed that the photoautotrophic hairy root cells possessed well-developed chloroplasts. The activities of ascorbate peroxidase and guaiacoal peroxidase found in the hairy roots were comparable to those found in the leaves and roots of parent plants of pak-bung, respectively. The elongation rate of growing points of the hairy roots was maximum at 5.0% CO2 concentration in gas phase and an incident light intensity of 10 W/m2 under the photoautotrophic conditions examined. Although light was indispensable for ensuring photoautotrophy of the hairy roots, it was found that exposure of the roots to strong light resulted in the reduction in the number of viable growing points governing the overall growth rate of the hairy roots. 相似文献
55.
Ferroelectric properties of ultrathin films of Nylon 11 were investigated. The thickness was in the range of 25 to 55 nm. Ferroelectric response was largely affected by thermal annealing and following cooling conditions. Thermal annealing at higher temperature followed by quenching in liquid nitrogen gave larger remanent polarization and smoother surface, whereas cooling down in an ambient atmosphere caused smaller remanent polarization and rough surface. Surface roughness strongly affected the polarization reversal and remanent polarization. Hydrogen bonding in crystal was also significantly related to the polarization reversal and thus remanent polarization. 相似文献
56.
57.
Naoto Kasahara Kyotada Nakamura Masaki Morishita Hiroshi Shibamoto Kazuhiko Inoue 《Nuclear Engineering and Design》2008,238(2):287-298
For realization of economical and reliable fast reactor (FR) plants, the Japan Atomic Energy Agency (JAEA) and the Japan Atomic Power Company (JAPC) are cooperating on the “Feasibility Study on Commercialized FR Cycle Systems”. To certify the design concepts through evaluation of the structural integrity of FR plants, the research and development of the “Elevated Temperature Structural Design Guide for Commercialized Fast Reactor (FDS)” is recognized as an essential theme. The FDS focuses on particular failure modes of FRs such as ratchet deformation and creep-fatigue damage due to cyclic thermal loads. For precise evaluation of these modes, the research and development for three main issues is in progress. First, the “Refinement of Failure Criteria” needs to be addressed for particular failure modes of FRs. Secondly, the development of “Guidelines for Inelastic Design Analysis” is conducted to predict elastic plastic and creep deformation under elevated temperature conditions. Lastly, efforts are being made toward preparing “Guidelines for Thermal Load Modeling” for the design of FR components where thermal loads are dominant. 相似文献
58.
Diah Permata Naoto Nagaoka 《IEEJ Transactions on Electrical and Electronic Engineering》2014,9(Z1):S37-S43
A method to measure a small capacitance with its loss resistance using a set of transient current waveforms is proposed in this paper. The parameters are obtained from the time constants in the time domain. The method has high resistance to extraneous noise, because a time‐to‐frequency transformation, which is sensitive to noise, is not required. The transient current waveforms are obtained by a voltage or current source, a current transformer, and a waveform recorder. The measured capacitance by the proposed method is not affected by the capacitance of the voltage probe, because it is obtained without any voltage information. The sheath surge impedance of the current injection cable, which is indispensable for the transient measurement, is corrected. The application of the method has the advantage in that it allows the modeling of a fast transient of a power apparatus, comparing it with the steady‐state measurement using an impedance measuring instrument. The proposed method is applied to create an equivalent circuit between electrodes implanted into a piece of wood, and its reliability is confirmed by comparison between the measured and calculated results. Stray capacitances of a miniature circuit breaker are also measured, and the results show that the proposed method is applicable to equipment in power systems. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
59.
An aqueous suspension system for phospholipase D-mediated synthesis of PS without toxic organic solvent 总被引:1,自引:2,他引:1
Yugo?Iwasaki Yukiko?Mizumoto Takahiro?Okada Takaya?Yamamoto Kentaro?Tsutsumi Tsuneo?YamaneEmail author 《Journal of the American Oil Chemists' Society》2003,80(7):653-657
Enzymatic synthesis of PS by phospholipase D (PLD)-mediated transphosphatidylation in an aqueous media was investigated. The
purpose of this study was to establish a novel synthetic method where no toxic organic solvents were used. An attempt to react
soybean lecithin (simply dispersed in an aqueous buffer) with an aqueous solution of l-serine and PLD was unsuccessful, giving only 20% of PS. By contrast, a suspension of lecithin adsorbed on fine powders such
as silica was effectively converted into PS in an aqueous solution of l-serine and PLD. After screening various powders for use as the lecithin adsorbent, calcium sulfate was found to be the best
with respect to lecithin conversion. In addition, calcium sulfate did not require prior adsorption of lecithin (i.e., the
reaction proceeded effectively simply by adding the powder to an aqueous mixture of lecithin, l-serine, and PLD). With this “aqueous suspension system” of calcium sulfate, up to 180 mg/mL lecithin was completely converted,
resulting in more than 80% PS in 24 h. The synthesized PS could easily be recovered from the powder by extracting with a mixture
of n-hexane, ethanol, and diluted HCl. 相似文献
60.
Kazuhiko Kandori Naoto Horigami Akemi Yasukawa Tatsuo Ishikawa 《Journal of the American Ceramic Society》1997,80(5):1157-1164
The texture of fibrous calcium hydroxyapatite (Ca10 -(PO4 )6 (OH)2 , CaHAP) particles that were prepared by the decomposition of calcium–ethylenediaminetetraacetic acid (calcium–EDTA) chelates at 100°C under various pH conditions (pH values of 5–10) was investigated by various means. Well-crystallized fibrous CaHAPs were produced at pH .6. The stoichiometry of the CaHAPs with a chemical formula of Ca10− x (HPO4 ) x (PO4 )6− x (OH)2− x (H2 O) x was improved by increasing the decomposition pH. All the CaHAPs had unit-cell dimensions of a = 0.9436 ± 0.0003 nm and c = 0.6881 ± 0.0006 nm, exhibiting an enlarged a value. The finding of mesoporosity of CaHAPs by nitrogen gas (N2 ) adsorption measurement indicated that the CaHAPs were produced by an agglomeration of primary particles. Furthermore, the nonstoichiometric CaHAPs that formed at pH 6 developed ultramicropores, which were accessible to water (H2 O) molecules but not to N2 molecules, by the elimination of H2 O molecules that were adsorbed in interstices of primary particles in less-orderly crystallized CaHAPs and/or by dehydration of HPO4 2− groups. These findings by gas adsorption techniques could give evidence for the agglomeration mechanism to attain a polycrystalline CaHAP, although they exhibited good crystallinity with large size. 相似文献