全文获取类型
收费全文 | 7615篇 |
免费 | 161篇 |
国内免费 | 35篇 |
专业分类
电工技术 | 515篇 |
综合类 | 20篇 |
化学工业 | 1915篇 |
金属工艺 | 202篇 |
机械仪表 | 179篇 |
建筑科学 | 230篇 |
矿业工程 | 1篇 |
能源动力 | 298篇 |
轻工业 | 644篇 |
水利工程 | 27篇 |
石油天然气 | 9篇 |
无线电 | 615篇 |
一般工业技术 | 1296篇 |
冶金工业 | 874篇 |
原子能技术 | 261篇 |
自动化技术 | 725篇 |
出版年
2023年 | 35篇 |
2022年 | 76篇 |
2021年 | 132篇 |
2020年 | 67篇 |
2019年 | 81篇 |
2018年 | 105篇 |
2017年 | 94篇 |
2016年 | 150篇 |
2015年 | 107篇 |
2014年 | 183篇 |
2013年 | 414篇 |
2012年 | 241篇 |
2011年 | 407篇 |
2010年 | 330篇 |
2009年 | 356篇 |
2008年 | 389篇 |
2007年 | 340篇 |
2006年 | 262篇 |
2005年 | 282篇 |
2004年 | 249篇 |
2003年 | 217篇 |
2002年 | 205篇 |
2001年 | 151篇 |
2000年 | 133篇 |
1999年 | 165篇 |
1998年 | 388篇 |
1997年 | 238篇 |
1996年 | 196篇 |
1995年 | 121篇 |
1994年 | 130篇 |
1993年 | 149篇 |
1992年 | 88篇 |
1991年 | 123篇 |
1990年 | 84篇 |
1989年 | 101篇 |
1988年 | 91篇 |
1987年 | 62篇 |
1986年 | 109篇 |
1985年 | 84篇 |
1984年 | 72篇 |
1983年 | 81篇 |
1982年 | 84篇 |
1981年 | 71篇 |
1980年 | 61篇 |
1979年 | 59篇 |
1978年 | 55篇 |
1977年 | 46篇 |
1976年 | 44篇 |
1975年 | 24篇 |
1973年 | 25篇 |
排序方式: 共有7811条查询结果,搜索用时 15 毫秒
1.
Masami Ikeda Susumu Fukumoto Hiroshi Takao Shinya Ohtsuka Eiichi Haginomori Masayuki Hikita 《Electrical Engineering in Japan》2002,141(4):16-24
This paper describes the dielectric breakdown characteristics of oil and oil‐impregnated paper for very fast transient (VFT) voltages. Blumlein circuits generate VFT voltages of 60 and 300 ns in a pulse width that simulates disconnecting switching surges in gas‐insulated switch gears. We measured the breakdown voltages of needle‐to‐plane, plane‐to‐plane oil gaps and several pieces of paper between plane electrodes for VFT and lightning impulse voltages. The measured data were formulated in V‐t characteristics and Weibull probability distributions. The inclination n of V‐t characteristics of insulating paper is 150, which is less than n = 13.7 of the plane‐to‐plane oil gap in the VFT time range. The shape parameters of Weibull distribution obtained in this study show that the scattering of breakdown voltages of paper is much less than that of oil. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 16–24, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10043 相似文献
2.
Hideo Sawada Hiroshi Kakehi Masashi Koizumi Yoshihiro Katoh Masashi Miura 《Journal of Materials Science》2007,42(17):7147-7153
Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [RF-(DOBAA)
n
-RF] reacted with tetraethoxysilane (TEOS) and silica nanoparticles in the presence of low-molecular weight biocides such as
hibitane, hinokitiol, and hinokioil under alkaline conditions to afford RF-(DOBAA)
n
-RF/silica nanocomposites-encapsulated these biocides in excellent to moderate isolated yields. Fluoroalkyl end-capped N,N-dimethylacrylamide oligomer [RF-(DMAA)
n
-RF] and acrylic acid oligomer [RF-(ACA)
n
-RF]/silica nanocomposites-encapsulated hibitane were obtained under similar conditions. Dynamic light scattering measurements
showed that the size of these fluorinated nanocomposites-encapsulated biocides thus obtained is nanometer size-controlled.
Additionally, these fluorinated nanocomposites were shown to have a good dispersibility and stability in methanol and water.
Of particular interest, these fluorinated nanocomposites-encapsulated biocides were found to have a good antibacterial activity
against Staphylococcus aureus, and these nanocomposites were applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate). 相似文献
3.
This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time‐consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct‐current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 7–15, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20310 相似文献
4.
Recently published studies indicate a potential clinical application of PET in head and neck tumors. In the preoperative staging phase, PET enables confirmation of regional lymph node extension and guides nodal neck dissection or systemic treatment. In this phase, a high negative predictive value, near 100%, could make it possible to avoid many negative neck dissections. This is a reliable technique for confirming or excluding the presence of recurrent/residual tumor and for obtaining an early evaluation of chemotherapeutic and radiotherapeutic response. PET imaging in many cases makes it possible to locate and guide histological study of tumors with an unknown primary. PET imaging for these indications is a perfect complementary method for clinical exploration and better than other imaging techniques. 相似文献
5.
Tadashi Hano Michiaki Matsumoto Takahisa Kawazu Takaaki Ohtake 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,62(1):60-63
The extraction equilibria of various di- and tripeptides with di-2-ethylhexylphosphoric acid (D2EHPA) were studied at low pH values. The complex extracted to organic phase consisted of one molecule of peptide and two molecules of D2EHPA dimer. The extraction constants of the peptides correlated well with the distribution coefficients of peptides between 1-octanol and water, which is a measure of hydrophobicity. The permeation rates of peptides through an emulsion liquid membrane were examined by using D2EHPA as a carrier, Span 80 as an emulsifier and kerosene as a diluent. The rates varied considerably with peptide type, depending upon the hydrophobicity. 相似文献
6.
A Ikeda K Fujimoto I Yoshii S Matsumoto K Nishitani K Ikeda 《Canadian Metallurgical Quarterly》1993,68(4):410-421
Ever since 1974, the cadaver has been embalmed by the arterial embalming method, using pre-embalming fluid with blood clot disperser and cell conditioner for the removal of blood clots and drainage of blood, at the Department of Anatomy of the Kawasaki Medical School. According to this method, the cadavers are always very well fixed so that they can be used for not only anatomical dissection but also research for the vascular system by vasography, kinematics of the joint and other histologic examinations. In this report we have described our embalming procedure concretely and its application to research. 相似文献
7.
Koichi Itagaki Md. Mortuza Ali Hiroshi Kitamura Takeo Maruyama 《Electrical Engineering in Japan》1992,112(2):1-10
Several sealed-off triggered vacuum gaps are connected in series to improve hold-off voltage. The characteristics of impulse breakdown voltage of these series-connected gaps are investigated experimentally. The sum hold-off voltage of series-connected gaps decreases to a unit hold-off voltage when the maximum value of voltage division ratio across the gaps increases to unity. Self-breakdown probability of the series-connected gaps is always higher than that of a single gap under the same conditions. Hence, stage efficiency of the multistage gap decreases with increasing number of stages. Its value is 90 percent with 2-stage gap and 75 percent with 5-stage gap, respectively, under the same voltage division ratio and the same gap length (2.0 mm) in each stage. Triggered breakdown voltage of 2- or 3- stage gap is several hundred volts when all gaps are triggered simultaneously at the peak of the main impulse wave and a working voltage range is nearly 100 percent in this case. The working voltage range decreases with number of stages. Its value is 45 percent with 3-stage gap and 15 percent with 5-stage gap, respectively, when one triggered gap is fired for switching. 相似文献
8.
Hiroshi Ito Takehiko Ishiguro Tokutaro Komatsu Nozomu Matsukawa Gunzi Saito Hiroyuki Anzai 《Journal of Superconductivity and Novel Magnetism》1994,7(3):667-669
The superconducting transition of the organic compoundsκ-(BEDT-TTF)2 X is studied by resistive measurement in a magnetic field up to 10 T applied normal to the conducting plane. For the salts withX=Cu[N(CN)2]Br andX=CuCN[N(CN)2] the transition shows fanshaped broadening caused by superconductivity fluctuation. For theX=Cu(NCS)2 salt the resistivity shows a peak in the transition region in a magnetic field below 4 T.This phenomenon is suppressed in defect-reduced samples for intralayer conduction. We discuss this peak in relation to the thermal fluctuation on the Josephson junction structures in this salt. 相似文献
9.
Toru Ikegami Hideyuki Negishi Dai Kitamoto Keiji Sakaki Tomohiro Imura Masayoshi Okamoto Yasushi Idemoto Nobuyuki Koura Tsuneji Sano Kenji Haraya Hiroshi Yanagishita 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(4):381-387
In order to produce highly concentrated bioethanol by pervaporation using an ethanol‐permselective silicalite membrane, techniques to suppress adsorption of succinic acid, which is a chief by‐product of ethanol fermentation and causes the deterioration in pervaporation performance, onto the silicalite crystals was investigated. The amount adsorbed increased as the pH of the aqueous succinic acid solution decreased. The pervaporation performance also decreased with decreasing pH when the ternary mixtures of ethanol/water/succinic acid were separated. Using silicalite membranes individually coated with two types of silicone rubber, pervaporation performance was significantly improved in the pH range of 5 to 7, when compared with that of non‐coated silicalite membranes in ternary mixtures of ethanol/water/succinic acid. Moreover, when using a silicalite membrane double‐coated with the two types of silicone rubber, pervaporation performance was stabilized at lower pH values. In the separation of bioethanol by pervaporation using the double‐coated silicalite membrane, removal of accumulated substances having an ultraviolet absorption maximum at approximately 260 nm from the fermentation broth proved to be vital for efficient pervaporation. Copyright © 2005 Society of Chemical Industry 相似文献
10.
Anju Sawada Takehiro Kubo Yosikazu Abe Kazuyuki Matsumoto 《Journal of Low Temperature Physics》1995,101(3-4):707-712
The isochoric pressure of bcc Solid3He in the vicinity of the triple point has been measured by changing the temperature stepwisely and waiting for thermal equilibrium. We observed anomalous pressure kinks of the temperature dependence in the paramagnetic region near the triple point. This anomaly appeared at 0.37 to 0.40 tesla, and disappeared below 0.36 tesla. Moreover, critical phenomena at the transition point from the paramagnetic phase (PP) to the high field phase was observed and the phase line curves toward the PP side. 相似文献