首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   117篇
  免费   20篇
电工技术   6篇
化学工业   40篇
金属工艺   6篇
建筑科学   4篇
能源动力   1篇
轻工业   33篇
石油天然气   1篇
无线电   10篇
一般工业技术   21篇
冶金工业   8篇
自动化技术   7篇
  2023年   1篇
  2022年   2篇
  2021年   1篇
  2019年   1篇
  2018年   3篇
  2017年   7篇
  2016年   8篇
  2015年   12篇
  2014年   5篇
  2013年   8篇
  2012年   6篇
  2011年   10篇
  2010年   8篇
  2009年   9篇
  2008年   4篇
  2007年   5篇
  2006年   4篇
  2005年   2篇
  2004年   6篇
  2003年   3篇
  2002年   1篇
  2001年   1篇
  1999年   6篇
  1998年   1篇
  1997年   3篇
  1996年   2篇
  1995年   1篇
  1994年   3篇
  1992年   2篇
  1991年   3篇
  1990年   3篇
  1989年   1篇
  1988年   2篇
  1985年   1篇
  1983年   2篇
排序方式: 共有137条查询结果,搜索用时 15 毫秒
121.
Enhancing adhesion is of primary importance in preparation of insert injection molded plastic–metal hybrids. Here, the combination of coupling agent application parameters and steel oxide microstructure effects on the adhesion in thermoplastic urethane–stainless steel hybrids was studied. The stainless steel oxide structure was first modified by electrolytical polishing and subsequent oxidation treatment, then the steel was coated with N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (γ-AEAPS) prior to overmolding with thermoplastic urethane. The properties of formed silane coatings and ultimately the thermoplastic urethane–stainless steel hybrids were determined by several microscopical methods, infrared spectroscopy and mechanical testing. The bond strength of hybrids depended on the silane layer thickness. Also the stainless steel surface oxide structure had a remarkable influence on the coating formation and the resulting hybrid bond strength.  相似文献   
122.
Forty-three primary mediastinal tumors or cysts were surgically treated in 41 patients during a 10-year period. These tumors consisted of 20 thymic tumors, 10 neurogenic tumors, 5 teratomas, 3 lymphoid tumors, 2 congenital cysts, 2 mediastinal thyroid tumors, and 1 chondroma. There were 16 male and 25 female patients. The mean age was 44 years with a range of 6 to 79 years. Sixteen patients (39%) were symptomatic. There were 20 thymic tumors including 13 thymomas, 5 thymic cysts, and 2 hyperplasia with myastenia. Additional radiation therapy was recommended for all but stage I thymomas. Only 1 of the 10 neurogenic tumors was malignant. Eight teratomas were all cystic and matured. Early operative intervention is mandatory in these cases.  相似文献   
123.
The separation of pinolenic acid from distilled tall oil fatty acid by the iodolactonization method was studied. The significance of prefractionation of tall oils and details of the iodolactonization procedure for the pinolenic acid purity achieved is discussed.  相似文献   
124.
A magnetic skyrmion is a nanometer‐scale magnetic vortex carrying an integer topological charge. Skyrmions show a promise for potential application in low‐power‐consumption and high‐density memory devices. To promote their use in applications, it is attempted to control the existence of skyrmions using low electric currents at room temperature (RT). This study presents real‐space observations for the current‐induced formation and annihilation of a skyrmion lattice (SkL) as well as isolated skyrmions in a microdevice composed of a thin chiral magnet Co8Zn9Mn3 with a Curie temperature, T C ≈ 325 K, above RT. It is found that the critical current for the manipulation of Bloch‐type skyrmions is on the order of 108 A m?2, approximately three orders of magnitude lower than that needed for the creation and drive of ferromagnetic (FM) domain walls in thin FM films. The in situ real‐space imaging also demonstrates the dynamical topological transition from a helical or conical structure to a SkL induced by the flow of DC current, thus paving the way for the electrical control of magnetic skyrmions.  相似文献   
125.
Physical vapor deposition polymerization was achieved by evaporating vinyl monomers followed by heat treatment. This technique was utilized for preparing a hole-transport layer (HTL) and emissive layers (EMLs) of organic light emitting diodes (OLEDs). Adivinyl derivative of tetraphenyldiaminobiphenyl, DvTPD, was used both for the HTL and for the host material of red phosphorescent EML. A vinyl derivative of bis(N-carbazolyl)benzene, vmCP, was used for the host material of blue phosphorescent EML. The ELMs were doped with red or blue-emitting phosphorescent iridium complexes modified with styril units. After characterizing the devices that have single EML of red or blue emission, an OLED having multilayered ELM was prepared by stacking these layers to achieve quasi-white emission. It was found that the deposition polymerization was effective to improve the emission efficiency. The improvement appeared to be related to the proper carrier balance in the EML.  相似文献   
126.
127.
128.
The total and individual sterol content in 21 oat samples (seven cultivars grown at three different locations in Sweden) were analysed by gas chromatography after acid hydrolysis. The total sterol content in these oat cultivars varied between 350–491 µg g−1 of dry weight of kernel. The most abundant phytosterol was β‐sitosterol (237–321 µg g−1) followed by campesterol (32–46 µg g−1), Δ5‐avenasterol (15–47 µg g−1) and stigmasterol (11–21 µg g−1). There was a statistically significant difference in total sterol content between cultivars (p < 0.05) but no effect was found for cultivation location. Furthermore when contents of Δ5‐avenasterol in hexane‐extracted oat oil and acid‐hydrolysed oat samples were compared, it was noticed that the content of Δ5‐avenasterol was lowered due to acid hydrolysis. © 1999 Society of Chemical Industry  相似文献   
129.
Toxicological and physiological effects of dehydroabietic acid (DHAA), a major poison to fishes in pulp and paper mill effluents, were studied by two experiments with rainbow trout, Salmo gairdneri Richardson: in the first, fish were acutely exposed for 4 days to an average DHAA concentration of 1.2 mg l−1 (Exp. I) and in the second for 30 days to an average of 20 μg DHAA l−1 (Exp. II).Compared to the controls, fish of Exp. I displayed a decreased relative weight of liver, an increased blood haematocrit, and increased haemoglobin as well as plasma protein concentrations. The aspartate aminotransferase activity of heart muscle was significantly elevated, as was also the lactate dehydrogenase (LDH) of white muscle tissue. In the blood plasma, the proportion of muscle type LDH activity was simultaneously increased. UDP-glucuronyl-transferase activities of liver and kidney were strongly decreased. Results suggest an increased and altered use of body energy reserves, decreased plasma volume and impaired liver function.Fish of Exp. II showed an increased relative weight of spleen. In addition, liver and gill LDH shifted towards heart-type. We conclude that 20 μg l−1 is close to the “minimum effective concentration” of DHAA to rainbow trout.  相似文献   
130.
Transition liquid phase (TLP) bonding has been conducted on a Hastelloy X using amorphous foil filler metals. The inserted fillers were made by rapid solidification of a Ni-15% Cr alloy containing 3 to 5 mass% boron as a melting point depressant. The microstructural change with isothermal bonding time from 2.4 to 38.4 ks was examined in the bond regions by optical microscopy and electron probe microanalysis (EPMA). An assessment of the bond strength was made by stress rupture tests performed at 1173 K. It was found that rupture strain and rupture life increased with increasing bonding time. A bond efficiency greater than 80% was achieved when the bonding time was 38.4 ks.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号