全文获取类型
收费全文 | 6558篇 |
免费 | 1207篇 |
国内免费 | 938篇 |
专业分类
电工技术 | 276篇 |
综合类 | 532篇 |
化学工业 | 1084篇 |
金属工艺 | 89篇 |
机械仪表 | 216篇 |
建筑科学 | 179篇 |
矿业工程 | 68篇 |
能源动力 | 135篇 |
轻工业 | 3624篇 |
水利工程 | 28篇 |
石油天然气 | 35篇 |
武器工业 | 25篇 |
无线电 | 681篇 |
一般工业技术 | 955篇 |
冶金工业 | 125篇 |
原子能技术 | 34篇 |
自动化技术 | 617篇 |
出版年
2024年 | 71篇 |
2023年 | 174篇 |
2022年 | 187篇 |
2021年 | 250篇 |
2020年 | 231篇 |
2019年 | 232篇 |
2018年 | 158篇 |
2017年 | 198篇 |
2016年 | 212篇 |
2015年 | 239篇 |
2014年 | 423篇 |
2013年 | 424篇 |
2012年 | 543篇 |
2011年 | 606篇 |
2010年 | 429篇 |
2009年 | 466篇 |
2008年 | 336篇 |
2007年 | 524篇 |
2006年 | 479篇 |
2005年 | 421篇 |
2004年 | 367篇 |
2003年 | 353篇 |
2002年 | 289篇 |
2001年 | 243篇 |
2000年 | 186篇 |
1999年 | 139篇 |
1998年 | 104篇 |
1997年 | 75篇 |
1996年 | 70篇 |
1995年 | 58篇 |
1994年 | 41篇 |
1993年 | 35篇 |
1992年 | 30篇 |
1991年 | 7篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1968年 | 2篇 |
1955年 | 4篇 |
排序方式: 共有8703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.
喷墨打印相纸及打印图像质量的分析 总被引:2,自引:1,他引:1
喷墨打印相纸随着数码相机的发展近几年在国内发展迅速。针对目前产品质量没有测量标准的现状,提出喷墨相纸的质量指标主要为4个,即白度、光泽度、油墨吸收性和防水性。给出了相应的测量方法。并指出相纸上油墨点的面积是衡量质量的第一重要指标,其次是点的圆度。另外对图像输出的质量介绍了一种科学的评价方法,即图像的逼真性分析。说明图像的打印墨点直径不应小于方形像素的对角线长,图像才能真实再现。 相似文献
3.
介绍了高可靠电镀Ni/Au工艺在PTFE微波印制电路上的应用,并分析了氨基磺酸盐镀软镍和亚硫酸盐镀软金工艺的影响因素及提高Ni/Au镀层之间附着力的措施。通过实验及应用证明了与直接镀金工艺相比,在软基材PTFE敷铜箔板上镀Ni/Au工艺能大大提高微波电路的可焊性,高温稳定性和长期可靠性,并且用其所制作的微波器件的高频性能也优于直接镀金工业。 相似文献
4.
P Sarkar D Ghosh D Bhattacharya R Kataky SJ Setford SF White APF Turner 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(12):1389-1394
Allergen levels in indoor environments, leading to many diseases, eg asthma, rhinitis and conjunctivitis, affect a large and increasing fraction of the population. A quite effective and inexpensive method of a rough but very rapid overall assessment of total allergen level in the environment has been developed. The method involved estimation of protein in allergen extracts by screen‐printed electrodes using two different techniques. The biosensor comprised a rhodinised carbon working electrode, a silver/silver chloride reference electrode and a carbon counter electrode. In the first method the enzyme protease reacted with allergen protein to release amino acid, which produced hydrogen peroxide in the presence of amino acid oxidase. This was detected amperometrically. The second method used potassium bromide as electrolyte and the electrode was subjected to dual potential. Bromine, released due to electrolysis at higher potential, was consumed by the allergen protein at lower potential. In the first method, a unique technique was used to microencapsulate the enzyme protease and immobilise it on the surface of the electrode by in‐situ polymerisation to avoid contact with the amino acid oxidase. A total of seven allergens were tested and the results gave a good correlation with the standard protein measurement method. Environmental specimens from indoors, schools and workplaces can be evaluated for the aeroallergens produced by dust mites, animal hairs, cockroach debris, pollens, etc as a means of determining the exposure risk. Copyright © 2005 Society of Chemical Industry 相似文献
5.
对2004年中国证券市场上的129家金属和非金属行业上市公司的会计账面盈利与现金流量的相关性进行实证研究后,发现两者的相关程度很低,很大一部分上市公司的账面盈利没有形成相应的现金流入,导致两者之间产生“滞脱”的效应.因此,笔者认为在对企业的财务状况进行评价时,不能仅仅局限于使用一些反映企业账面盈利的指标,应该还需要考虑一些反映企业创造现金流量能力的指标. 相似文献
6.
论科技论文英语摘要的表现形式 总被引:1,自引:0,他引:1
王定全 《武汉工业学院学报》2005,24(2):109-112
论述科技论文中英语摘要的文体风格、时态、语态和基本要求,并结合例句介绍了常用的表现形式,使之简洁、准确和流畅。 相似文献
7.
This article theoretically investigates the drying of uncoated paper with gas-fired infrared (IR) emitters installed within the drying section of a given commercial paper machine. Specifically, it presents the ideal location of two opposing IR emitters within the drying section. The ideal location of the two opposing IR emitters corresponds to the highest machine speed with specified average moisture content of paper sheet at the end of the drying section. This article also presents the average evaporation rate, temperature, and moisture content of the paper sheet as it travels through the drying section with the two opposing IR emitters operating at the optimum location. In addition, the temperature and moisture profiles in the sheet thickness direction, before and after the IR emitters, are provided. This article is not concerned with the potential effects of drying with IR emitters on paper sheet properties and machine runnability issues. 相似文献
8.
A series of long-chain quaternary ammonium halogen esters (UKK-chemicals), quaternary dimethyl tallow epoxypropyl ammonium
halogens (EPK1), quaternary ditallow methyl epoxypropyl ammonium halogens (EPK2), and EPK2 oligomers (EPK2P) were synthesized.
At acidic, neutral, or slightly basic conditions, EPK1-, EPK2-, EPK2P-, and UKK-chemicals operate as cationic chemicals. They
can be used, for example, as stock sizings, surface sizings, or fixatives. Stock sizing, surface sizing, and fixative experiments
indicate that EPK1-, EPK2-, EPK2P-, and UKK-chemicals function at least as well as or better than the corresponding synthetic
chemicals used in papermaking. 相似文献
9.
10.