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   30065篇
  免费   2564篇
  国内免费   898篇
电工技术   386篇
技术理论   17篇
综合类   3253篇
化学工业   2730篇
金属工艺   244篇
机械仪表   726篇
建筑科学   2515篇
矿业工程   244篇
能源动力   170篇
轻工业   12749篇
水利工程   438篇
石油天然气   212篇
武器工业   48篇
无线电   1268篇
一般工业技术   1528篇
冶金工业   1062篇
原子能技术   193篇
自动化技术   5744篇
  2025年   232篇
  2024年   677篇
  2023年   705篇
  2022年   1223篇
  2021年   1452篇
  2020年   1023篇
  2019年   1178篇
  2018年   1037篇
  2017年   1146篇
  2016年   930篇
  2015年   975篇
  2014年   1670篇
  2013年   1673篇
  2012年   1783篇
  2011年   1807篇
  2010年   1658篇
  2009年   1573篇
  2008年   1595篇
  2007年   1869篇
  2006年   1669篇
  2005年   1423篇
  2004年   1190篇
  2003年   971篇
  2002年   759篇
  2001年   545篇
  2000年   436篇
  1999年   384篇
  1998年   301篇
  1997年   237篇
  1996年   199篇
  1995年   175篇
  1994年   162篇
  1993年   127篇
  1992年   130篇
  1991年   66篇
  1990年   73篇
  1989年   48篇
  1988年   38篇
  1987年   36篇
  1986年   39篇
  1985年   33篇
  1984年   25篇
  1983年   31篇
  1982年   16篇
  1981年   18篇
  1980年   11篇
  1964年   13篇
  1957年   17篇
  1956年   11篇
  1955年   23篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Buffalo milk Cheddar cheese samples of different ages were analysed for compositional attributes (CA), ripening indices (RI) and Instron Textural Profile (ITP). All samples were compositionally alike, except for pH and salt-in-moisture (SM) contents. RI showed significant variations. CA and RI showed highly significant correlations within themselves and with each other, except for moisture with pH, SM with moisture, MNFS, Fat and FDM and Fat with MNFS. The ITPs of cheeses showed significant variations and had highly significant intercorrelations indicating their interdependence. CA (except moisture and MNFS) and RI showed a highly significant correlationship with ITPs. Moisture content showed a highly significant correlationship with all ITPs, except cohesiveness and springiness, where it was significant. MNFS content showed significant correlations only with hardness and brittleness. Stepwise regression analysis revealed that MI was the most predominant factor influencing cheese texture, followed by pH, SM, FDM and TVFA. Knowing Ca and RI, the textural properties of cheeses can be forecast through mathematical equations. Similarly the age of cheese can also be predicted if RI and/or textural properties are known.  相似文献   
3.
A mini spray dryer has been used to investigate morphological changes that occur to milk particles during the spray drying process. We have found that the mini spray dryer is ideal for such investigations, because phenomena such as skin and vacuole formation in particles can be analyzed without the added complication of particle agglomeration, which only occurs in much larger spray dryers where particle number concentrations are higher. We have confirmed observations made by various researchers that the bulk density of spray-dried milk powder is greatly affected by the drying temperature, due to the strong influence of the latter on the porosity of the particles. In addition, we have attempted to explain observations made by various workers that fat accumulates preferentially at the surface of a particle during drying by postulating that fluid fat is transported towards the surface, via a network of cracks and pores, by the development of a vacuole overpressure which is also responsible for the inflation of the particle. Finally, we have shown that milk powders can be spray dried a second time, by reconstitution with water, with no change to the thermodynamic characteristics of the resultant powder. Thus, milk concentrates for spray drying research can be prepared from already-spray-dried milk powders rather than using the more arduous evaporation method to concentrate unprocessed milk.  相似文献   
4.
Vibro-fluidized beds are widely used in drying sticky powders and agglomerated materials as milk powder. Using a vibro-fluidized laboratory scale dryer, this work is aiming at analyzing preliminarily the effect of its operational variables on the drying kinetics and characteristics of whole milk powder. The full-factorial design technique with three replications at the central point has been employed to generate data and correlations to quantify the effect of inlet air temperature, air flow rate, and vibration bed amplitude on the drying curves and the milk powder properties related to its faster reconstitution in water (as tapped density, Hausner cohesion ratio, agglomerate size distribution, and internal pore concentration). Results obtained are analyzed and discussed to identify the adequate operation condition for final drying whole milk powder in vibro-fluidized beds, assuring a high product quality.  相似文献   
5.
Cladosporium herbarum grown as a surface culture in a chemically defined medium of sucrose and inorganic salts gave a high yield of fat (29.2%). The component acids of this fat have been found to be palmitic (34.2%); oleic (15.9%); linoleic (34.2%) and linolenic (15.7%). The combined proportion of linoleic and linolenic acids being about 50 per cent, the fat will be of great value for the manufacture of oil-modified resins as the films produced by such resins do not become yellow with age.  相似文献   
6.
To study the conservation of peroxisomal targeting signals, we have determined the intracellular localization of human peroxisomal catalase when expressed in yeast. Using immunofluorescence, differential centrifugation and immunoelectron microscopy, we show that the protein is targeted to the peroxisomes of the heterologous cell and assembled in its active tetrameric form. These data show the conservation of the catalase targeting signal and import specificity between human and yeast peroxisomes.  相似文献   
7.
以推动人类文明进步发展的观念为先导,以详实的地质学、岩石学、石文化史料为切入点,介绍了我国观赏石文化的起源、发展及现状;阐述了赏石审美的本质、形式、石体标准、传统性、现代性等理论要点及其以小见大、以丑为美的审美理念。对赏石修身养性、以石陶情及赏石文化与道教情结的学术价值进行了评述;对从古至今的中华文化名人为赏石理论的创立、鉴赏、收藏和发展作出的不可磨灭的历史贡献进行了评价。  相似文献   
8.
在高校开展少数民族传统优秀体育项目教学,不仅能使少数民族传统体育走向规范化、科学化,较好地展现学生的运动能力,培养民族文化情感,激发民族热情,更重要的是还能提高学生的身心健康和综合素质,有利于对民族传统体育的继承、发展和广泛地传播。  相似文献   
9.
当前,医院的信息化建设飞速发展,很多中医院具备一流的网络设施和计算机设备,但是“信息孤岛”的现象却广泛存在,究其原因就是缺乏统一的信息系统标准。本文分析了中医院信息系统标准化建设存在的问题,问题出现的原因,初步探讨了解决中医院信息系统标准化建设的办法。  相似文献   
10.
近年来,正当许多发达国家努力发展本土文化的时候,我国在很多方面特别是艺术设计教育领域却忽视了具有5000年历史的中国传统文化。传统文化在现代设计教育中缺失的问题,表面上是教育体系、教育方法的问题,实际是教育理念的问题。面对西方文化巨大冲击,完善我国现代设计教育体系,确保民族文化根脉的活力,是我们必须面对、也必须尽快解决的问题。  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