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   12935篇
  免费   447篇
  国内免费   58篇
电工技术   268篇
综合类   16篇
化学工业   2325篇
金属工艺   374篇
机械仪表   361篇
建筑科学   221篇
矿业工程   73篇
能源动力   709篇
轻工业   1174篇
水利工程   190篇
石油天然气   82篇
无线电   1640篇
一般工业技术   2822篇
冶金工业   1559篇
原子能技术   201篇
自动化技术   1425篇
  2024年   41篇
  2023年   183篇
  2022年   511篇
  2021年   520篇
  2020年   418篇
  2019年   413篇
  2018年   571篇
  2017年   522篇
  2016年   492篇
  2015年   284篇
  2014年   453篇
  2013年   891篇
  2012年   529篇
  2011年   683篇
  2010年   548篇
  2009年   543篇
  2008年   485篇
  2007年   394篇
  2006年   342篇
  2005年   267篇
  2004年   246篇
  2003年   221篇
  2002年   181篇
  2001年   146篇
  2000年   150篇
  1999年   156篇
  1998年   357篇
  1997年   231篇
  1996年   252篇
  1995年   219篇
  1994年   182篇
  1993年   172篇
  1992年   143篇
  1991年   152篇
  1990年   114篇
  1989年   108篇
  1988年   130篇
  1987年   110篇
  1986年   89篇
  1985年   115篇
  1984年   94篇
  1983年   107篇
  1982年   99篇
  1981年   88篇
  1980年   78篇
  1979年   54篇
  1978年   46篇
  1977年   56篇
  1976年   76篇
  1975年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Multimedia Tools and Applications - In the way of communication, facial expression act as non-verbal communication and play an important role in social interaction by providing some contextual...  相似文献   
22.
Effect of debittered salmon frame hydrolysate (DSFH) at various levels (0, 5, 10, 15, 20 and 25 g/100 g) on physicochemical, textural, sensory and nutritional properties of biscuits was investigated. The highest thickness was obtained for the sample with 25 g/100 g DSFH (P < 0.05). There was no difference in diameter among all the biscuit samples (P > 0.05). The samples added with DSFH had lower weight, water activity and moisture content than the control (CONT, without DSFH) (P < 0.05). DSFH at 15 g/100 g showed no detrimental effect on sensory properties of resulting biscuits (DSFH-15). The DSFH-15 biscuit showed reduction in cutting force and fracturability. Scanning electron microscopic and cross-sectional images showed that DSFH-15 biscuit had more porous structure, compared to the CONT. The biscuits fortified with 15 g/100 g DSFH had higher protein but had lower energy value, fat and carbohydrate content than the CONT.  相似文献   
23.
Clean Technologies and Environmental Policy - Manufacturing organizations are under continuous pressure to implement sustainability in their activities. There is a need to identify the...  相似文献   
24.
The patterning of contact holes by selecting out-of-focus image plane (defocus) using attenuated phase shift masks (APSM) has been studied. Defocus is found to enhance the image modulation at low partial coherence for contact holes with negative local average of mask function. Semi-dense holes up to 130 nm in 8% APSM have been printed by 0.5 μm defocus at a partial coherence of 0.31 using KrF scanner with highest numerical aperture of 0.68. However, these holes were closed with in-focus imaging. Defocus is also found to be beneficial for patterning the pitches that have extensive side lobes with in-focus imaging.  相似文献   
25.
The nature of pairing mechanism as well as transition temperature of yttrium cuprates is discussed using the strong coupling theory. An interaction potential has been developed for the layered structure with two conducting CuO2(a–b) layers in a unit cell. The interaction potential properly takes care of electron-electron, electron-phonon and electron-plasmon interactions. Furthermore, the electron-phonon coupling parameter (λ), the modified Coulomb repulsive parameter (μ*) and the 2D acoustic phonon (plasmon) energy as a function of oxygen deficiency is worked out. Finally, the superconducting transition temperature (T c) is then evaluated by using these coupling parameters and obtainedT c = 95(92)K for Y(Yb)Ba2Cu3O7−δ superconductors withδ = 0·0. The model parameters estimated from the layered structure approach are consistent with the strong coupling theory. The result deduced on the variation ofT c withδ are in fair agreement with the earlier reported data on yttrium cuprates. The analysis of the above results are discussed.  相似文献   
26.
27.
The electrochemical and corrosion behaviour of a nickel base super alloy (C-263) has been investigated in the deaerated binary and ternary solution mixture of concentrated phosphoric acid, acetic acid, sulphuric acid, nitric acid or water using potentiostatic technique at 35°C. The possibilities of electropolishing of this alloy in these solution mixtures have been also explored. The alloy showed distinct active, passive and transpassive behaviour in the experimental solutions. The alloy remained active and turned passive in the negative potential region. Transpassive dissolution of the alloy is observed and electropolishing is achieved in this region. The best electropolishing is obtained in 50% H3PO4 + 40% CH3COOH + 10% H2SO4. Higher content of water in the electrolytic solution is not useful for electropolishing of the alloy The experimental results also suggest that a current plateau in the transpassive potential region is not a sufficient condition to achieve electropolishing.  相似文献   
28.
The physicochemical and functional properties of convection oven- and freeze-dried gluten meals of two corn varieties were evaluated. The physicochemical properties (water solubility index, water absorption index, Hunter color parameters, and bulk density) and functional properties (water absorption, oil absorption, least gelation concentration, protein solubility, and emulsification properties) of convection-oven and freeze-dried corn gluten meals were compared with each other and soy flour. Freeze-dried corn gluten meals was observed to have lower bulk density (0.244-0.263 kg/m3) and was lighter in color (high L and ΔE) compared to their counterpart convection oven-dried gluten meals. Freeze-dried gluten meals from both corn varieties showed significantly higher oil absorption, water absorption, pH, emulsification, and protein solubility compared to oven-dried corn gluten meals. The gluten meals from both corn varieties had lower water absorption and bulk density but higher oil absorption than soy flour, suggesting the hydrophobic nature of corn proteins. Corn gluten meals formed thin (pourable) emulsions compared to soy flour emulsions, which were thick salad dressing type. Freeze- and convection oven-dried corn gluten meals showed significantly lower protein solubility measured at different pH than soy flour.  相似文献   
29.
Dielectric relaxation behaviour of (1 − x)PMN − xPZ, for x = 0.10, 0.30 and 0.40 have been studied. The nature of relaxational behaviour was found to change with PZ concentration. A crossover from a static freezing to critical slowing down like behaviour is observed with increase in Zr4+ concentration. We have used Glazounov and Tangastev criterion to distinguish freezing and critical slowing down like behaviour.  相似文献   
30.
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