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   404024篇
  免费   5411篇
  国内免费   1366篇
电工技术   7578篇
综合类   316篇
化学工业   60015篇
金属工艺   16446篇
机械仪表   13526篇
建筑科学   8364篇
矿业工程   2154篇
能源动力   11579篇
轻工业   28510篇
水利工程   4272篇
石油天然气   7915篇
武器工业   17篇
无线电   49385篇
一般工业技术   83168篇
冶金工业   75062篇
原子能技术   9188篇
自动化技术   33306篇
  2022年   2591篇
  2021年   3942篇
  2020年   2988篇
  2019年   3842篇
  2018年   6534篇
  2017年   6535篇
  2016年   6969篇
  2015年   4337篇
  2014年   7176篇
  2013年   20089篇
  2012年   11447篇
  2011年   15320篇
  2010年   12180篇
  2009年   13740篇
  2008年   14085篇
  2007年   13844篇
  2006年   12439篇
  2005年   11135篇
  2004年   10521篇
  2003年   10441篇
  2002年   9847篇
  2001年   9745篇
  2000年   9145篇
  1999年   9537篇
  1998年   24350篇
  1997年   16723篇
  1996年   12812篇
  1995年   9532篇
  1994年   8373篇
  1993年   8394篇
  1992年   6055篇
  1991年   5697篇
  1990年   5684篇
  1989年   5322篇
  1988年   5045篇
  1987年   4426篇
  1986年   4303篇
  1985年   4812篇
  1984年   4423篇
  1983年   3997篇
  1982年   3655篇
  1981年   3733篇
  1980年   3433篇
  1979年   3330篇
  1978年   3338篇
  1977年   3756篇
  1976年   4858篇
  1975年   2853篇
  1974年   2663篇
  1973年   2732篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
182.
183.
Wireless Personal Communications - Due to the widely spreading of fake news utilizing image manipulation and its bad effects, this paper investigates efficient image contents verification and...  相似文献   
184.
185.
186.
The objective of this study was to determine the effect of complexation of oxidised starch with mineral elements on its physicochemical properties. Corn starch was oxidised with sodium hypochlorite and, afterwards, modified with ions of potassium, magnesium and iron. Thus, native and modified starches were analysed for: contents of mineral elements, colour parameters (L*a*b*), water binding capacity and solubility in water at temperature of 60 and 80 °C. Thermodynamic characteristics of gelatinisation by DSC, molecular weight distribution by GPC, intrinsic viscosity and pasting properties by RVA were studied. The efficiency of incorporation of metal ions into oxidised corn starch was about 30%, 20% and 20% for potassium, magnesium and iron ions, respectively. The complexation with potassium ions caused the greatest changes in the molecular weight distribution and the intrinsic viscosity of starches and viscosity of starch pastes. Only modification of starch with iron ions affected the colour parameters of the starch. Incorporation of metal ions into starch resulted also in changes in its water binding capacity and solubility in water.  相似文献   
187.
188.
189.
The heat capacity of ytterbium orthovanadate was first measured by adiabatic calorimetry in the temperature range T?=?12.28–344.06?K. No obvious anomalies were observed on the curve obtained. The values of standard thermodynamic functions in the temperature range T?=?0–400 K were calculated. Based on low-temperature calorimetry data obtained, previously published data on the high-temperature heat capacity of ytterbium orthovanadate were corrected. The anomalous contribution to heat capacity for YbVO4 was compared with the data known for YbPO4.  相似文献   
190.
This research examined the male and female novice designers toward color associations for the concepts used for ‘warnings’, ‘action required’, and ‘signs and equipment status’ through a questionnaire‐based study. A total of 178 Hong Kong Chinese final year undergraduate design students (89 males and 89 females) participated in the study. The test used required the participants to indicate their choice of one of nine colors to associations with each of 38 concepts in a color‐concept table, so that any one color could be associated with any one of the concepts. For both male and female groups of novice designers, chi‐square tests revealed a strong color association for each concept tested in this study (< .05). The results showed males and females agreed on some color‐concept association stereotypes which were therefore gender neutral. The male and female novice designers had the same color associations and similar levels of stereotype strengths for 21 concepts. The nine strongest and therefore most useful color‐concept association stereotypes for both male and female novice designers were: red‐danger, red‐fire, red‐hot, red‐stop, red‐emergency, red‐error, blue‐cold, blue‐male, and green‐exit. However, the male and female novice designers had different color association stereotypes for the standby (green vs. yellow), emergency exit (green vs. red), and toxic (purple vs. black) concepts, and the strengths of the 14 remaining associations for both groups were not at equivalent levels. Overall, it is anticipated that the findings of this study will act as a useful reference for novice designers and other design practitioners to optimize color coding in the design of ‘warnings’, ‘action required’, and ‘signs and equipment status’ messages.  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