首页 | 官方网站   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   363449篇
  免费   3976篇
  国内免费   1449篇
工业技术   368874篇
  2021年   2261篇
  2019年   2196篇
  2018年   11491篇
  2017年   12022篇
  2016年   8373篇
  2015年   3103篇
  2014年   4697篇
  2013年   12713篇
  2012年   9853篇
  2011年   17966篇
  2010年   15354篇
  2009年   15399篇
  2008年   15663篇
  2007年   17547篇
  2006年   8393篇
  2005年   11129篇
  2004年   9463篇
  2003年   8998篇
  2002年   7895篇
  2001年   7475篇
  2000年   7102篇
  1999年   7293篇
  1998年   18087篇
  1997年   12757篇
  1996年   9809篇
  1995年   7474篇
  1994年   6555篇
  1993年   6633篇
  1992年   4704篇
  1991年   4499篇
  1990年   4380篇
  1989年   4349篇
  1988年   4017篇
  1987年   3617篇
  1986年   3610篇
  1985年   3965篇
  1984年   3648篇
  1983年   3398篇
  1982年   3185篇
  1981年   3195篇
  1980年   3167篇
  1979年   2944篇
  1978年   2970篇
  1977年   3366篇
  1976年   4435篇
  1975年   2508篇
  1974年   2456篇
  1973年   2478篇
  1972年   2087篇
  1971年   1829篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
121.
A simple but comprehensive model considering homogeneous and micellar nucleation, coagulation, entry of radicals to particles and to micelles and radicals' exit from particles, is presented. The model is validated, in a starved semicontinuous heterophase polymerization of ethyl methacrylate, at three monomer addition rates. The model accurately describes the overall and instantaneous conversion, the average particle density and diameter, and the number and weight average molar masses evolutions over time. It is found that even though the average number of radicals is much smaller than 0.5, the system is not 0-1. An empirical function was used to describe the gel effect. The homogeneous nucleation was the prevailing mechanism for particle formation and large exit rates of radicals were observed. POLYM. ENG. SCI., 60: 223–232, 2019. © 2019 Society of Plastics Engineers  相似文献   
122.
Technical Physics Letters - The C–V characteristics of Au/Al2O3/In0.52Al0.48As and Au/SiO2/In0.52Al0.48As metal–insulator–semiconductor structures have been studied. It has been...  相似文献   
123.
124.
125.
This study evaluated several physical and sensory parameters of different types of cheese available in the Polish market. The measurements of textural properties were conducted in an Instron universal testing machine, while the colour properties of cheeses were measured using a Minolta chromameter. The chemical composition was determined by means of the near‐infrared spectroscopy (NIRs). Moreover, a trained sensory panel was invited to assess the cheese texture‐related properties. Generally, cheeses with reduced fat content were characterised by higher hardness, adhesiveness, cohesiveness and elasticity. Texture‐related parameters of cheese with canola oil were comparable to that of most of full‐fat cheeses. The correlation analysis between physical and sensory attributes related to cheese textural properties indicated the potential applications of TPA, shear and penetration tests (= 0.766, = 0.75 and = 0.765, respectively) for the evaluation of sensory properties related to the hardness. Meanwhile, the elasticity of cheese obtained from sensory evaluation was strongly correlated with the elasticity determined from the shear test (= 0.722) and moderately correlated with the elasticity from penetration test (= 0.588), indicating a need to refine the method of penetration test. In addition, cheeses exhibited higher meltability during convection heating at 230 °C than microwave heating. The values of meltability for cheese with reduced fat content were lower than those of full‐fat cheese.  相似文献   
126.
127.
128.
129.
130.
Many e-commerce companies collect users’ personal data for marketing purposes despite privacy concerns. Information-collecting companies often offer a monetary reward to users to alleviate privacy concerns and ease the collection of personal information. This study focused on the negative effects of monetary rewards on both information privacy concerns (IPC) and information disclosure. A survey approach was used to collect data and 370 final responses were analysed using a two-way analysis of variance and a binomial logistic regression model. The results show that monetary rewards increase IPC when an information-collecting company requires sensitive information. Additional results indicate that building trust is a more effective way of collecting personal data. This study identifies how organisations can best execute information-collection activities and contributes additional insights for academia and practitioners.  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-23

京公网安备 11010802026262号