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   1180篇
  免费   39篇
  国内免费   3篇
电工技术   29篇
化学工业   215篇
金属工艺   31篇
机械仪表   37篇
建筑科学   10篇
能源动力   41篇
轻工业   125篇
水利工程   1篇
石油天然气   6篇
无线电   257篇
一般工业技术   248篇
冶金工业   111篇
原子能技术   5篇
自动化技术   106篇
  2023年   7篇
  2022年   19篇
  2021年   44篇
  2020年   22篇
  2019年   28篇
  2018年   29篇
  2017年   29篇
  2016年   21篇
  2015年   16篇
  2014年   39篇
  2013年   75篇
  2012年   46篇
  2011年   57篇
  2010年   69篇
  2009年   38篇
  2008年   48篇
  2007年   32篇
  2006年   26篇
  2005年   34篇
  2004年   33篇
  2003年   15篇
  2002年   13篇
  2001年   17篇
  2000年   20篇
  1999年   23篇
  1998年   38篇
  1997年   32篇
  1996年   19篇
  1995年   35篇
  1994年   31篇
  1993年   28篇
  1992年   23篇
  1991年   25篇
  1990年   25篇
  1989年   23篇
  1988年   18篇
  1987年   9篇
  1986年   11篇
  1985年   9篇
  1984年   10篇
  1983年   8篇
  1982年   9篇
  1981年   9篇
  1980年   14篇
  1979年   4篇
  1978年   6篇
  1977年   5篇
  1976年   13篇
  1975年   6篇
  1973年   3篇
排序方式: 共有1222条查询结果,搜索用时 0 毫秒
1.
Anup Bhat B  Harish SV  Geetha M 《ETRI Journal》2021,43(6):1024-1037
Mining high utility itemsets (HUIs) from transaction databases considers such factors as the unit profit and quantity of purchased items. Two-phase tree-based algorithms transform a database into compressed tree structures and generate candidate patterns through a recursive pattern-growth procedure. This procedure requires a lot of memory and time to construct conditional pattern trees. To address this issue, this study employs two compressed tree structures, namely, Utility Count Tree and String Utility Tree, to enumerate valid patterns and thus promote fast utility computation. Furthermore, the study presents an algorithm called single-phase utility computation (SPUC) that leverages these two tree structures to mine HUIs in a single phase by incorporating novel pruning strategies. Experiments conducted on both real and synthetic datasets demonstrate the superior performance of SPUC compared with IHUP, UP-Growth, and UP-Growth+ algorithms.  相似文献   
2.
When examined using continuous wave electron paramagnetic resonance and nuclear magnetic resonance spectrometers, the highT c superconductors give rise to intense, low field, ‘non-resonant’ absorption signals in the superconducting state. This phenomenon can be used as a highly sensitive, contactless technique for the detection and characterization of superconductivity even in samples containing only minute amounts of the superconducting phase. Further, it can also be applied to the determination of material parameters of interest such asJ c andH c2 in addition to being a powerful way of distinguishing between weak-link superconductivity and bulk superconductivity. The details of these aspects are discussed.  相似文献   
3.
The effect of enzymatic hydrolysis of proteins in milk using neutrase on the growth of the probiotic strain Bifidobacterium bifidus was evaluated by estimation of microbial growth, acidity, viscosity and flavour production. A significant increase in the growth of B bifidus was observed in neutrase‐hydrolysed milk. The setting time of bifidus‐cultured milk was advanced by about 12 h at 5% degree of hydrolysis. Enzymatic hydrolysis of proteins prior to cultivation also significantly increased the viscosity of the product. An approximately 60% increase in viscosity of the product was observed in neutrase‐hydrolysed milk. Production of steam‐volatile monocarbonyls as an indication of development of flavour was also higher in neutrase‐hydrolysed milk. The concentration of steam‐volatile monocarbonyls was 2.47 µmol per 100 ml in neutrase‐hydrolysed milk but only 1.84 µmol per 100 ml in control milk at the setting point of the curd. © 2002 Society of Chemical Industry  相似文献   
4.
Crystals of mixed NdLa heptamolybdates (max. size0.75×0.75×0.75 mm3) grown by silica gel technique were characterized using EDAX, IR, optical and scanning electron micrscopies.X-ray as well as electrn diffraction. The composition of the crystals was determined as (Nd1/2 La1/2 )2 Mo7O24·35H2O.The crystals exhibit varied morpholgies including square and octagonal platelets, cuboids, multifaceted crystal in coalesced and aggregated forms and spherulites.The XRD results indicate crystallinity of the grown material. Electron diffraction results suggest thermal instability of the material. IR results show the presence of peaks due to water and metal-oxygen bonds  相似文献   
5.
A discrete time domain model for the LCC-type parallel resonant power converter has been derived. This model has been used to predict the large signal behavior of the power converter. The peak component stresses and the dynamic response of the key state variables, as obtained from the large signal analysis, using PRO-MATLAB software are plotted. SPICE results are included to verify the analytical results. Experimental results are also presented to verify the theory  相似文献   
6.
监测正电源的电流时,通常使用高边检流放大器。然而,对于ISDN、电信电源,通常需要一个工作在负电源的检流放大器。本文介绍了一种采用MAX4460单电源仪表放大器设计负压检流放大器的方法。  相似文献   
7.
8.
Studies on the effect of nitrogen plasma on morphology and textile properties of mulberry silk fibers and fabrics have been conducted. The changes in the morphological structure have been monitored by transmission electron microscopy, X-ray diffraction, and internal reflection infrared spectroscopy. The changes in some of textile properties such as wettability, drying rate, and crease recovery owing to plasma treatment have also been investigated. It has been found that the surface of mulberry silk gets etched away, even affecting the crystalline region. This behavior is opposite to our findings on tassar silk. Therefore, an explanation of this differential behavior of mulberry with tasar on the basis of amino acid linkages vis-à-vis bonding, wettability, drying rate, and water retention capacity has been attempted. These results have been used to arrive at an understanding of internal structure of mulberry.  相似文献   
9.
Undoped and Te-doped gallium antimonide (GaSb) layers have been grown on GaSb bulk substrates by the liquid phase epitaxial technique from Ga-rich and Sb-rich melts. The nucleation morphology of the grown layers has been studied as a function of growth temperature and substrate orientation. MOS structures have been fabricated on the epilayers to evaluate the native defect content in the grown layers from theC-V characteristics. Layers grown from antimony rich melts always exhibitp-type conductivity. In contrast, a type conversion fromp- ton- was observed in layers grown from gallium rich melts below 400 C. The electron mobility of undopedn-type layers grown from Ga-rich melts and tellurium doped layers grown from Sb- and Ga-rich solutions has been evaluated. Paper presented at the poster session of MRSI AGM VI. Kharagpur. 1995  相似文献   
10.
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