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   805篇
  免费   19篇
  国内免费   5篇
电工技术   113篇
化学工业   189篇
金属工艺   14篇
机械仪表   19篇
建筑科学   10篇
矿业工程   2篇
能源动力   28篇
轻工业   83篇
水利工程   2篇
石油天然气   2篇
无线电   80篇
一般工业技术   144篇
冶金工业   68篇
原子能技术   27篇
自动化技术   48篇
  2023年   4篇
  2022年   5篇
  2021年   19篇
  2020年   6篇
  2019年   14篇
  2018年   13篇
  2017年   5篇
  2016年   14篇
  2015年   20篇
  2014年   14篇
  2013年   54篇
  2012年   33篇
  2011年   47篇
  2010年   34篇
  2009年   39篇
  2008年   46篇
  2007年   48篇
  2006年   39篇
  2005年   27篇
  2004年   26篇
  2003年   32篇
  2002年   17篇
  2001年   13篇
  2000年   22篇
  1999年   15篇
  1998年   33篇
  1997年   26篇
  1996年   12篇
  1995年   10篇
  1994年   10篇
  1993年   16篇
  1992年   6篇
  1991年   6篇
  1990年   10篇
  1989年   5篇
  1988年   8篇
  1987年   7篇
  1986年   10篇
  1985年   10篇
  1984年   6篇
  1983年   10篇
  1981年   10篇
  1980年   4篇
  1979年   2篇
  1978年   5篇
  1977年   5篇
  1976年   5篇
  1975年   2篇
  1971年   1篇
  1968年   1篇
排序方式: 共有829条查询结果,搜索用时 15 毫秒
71.
Phosphorylation is a useful method for improving the functional properties of food proteins. In this article, various methods of phosphorylation are reviewed. Dry-heating phosphorylation, a method developed recently, is also introduced. Some characteristics of phosphate groups are involved, and the effects of phosphorylation on the structural changes, the functional properties, and the physiological functions in vitro of food proteins, are discussed. The types of phosphate linkages and the phosphopeptides from phosphorylated proteins are identified. The molten (partially unfolded) conformations of food proteins formed by phosphorylation are discussed. The phosphorylation of food proteins improved a number of functional properties, including heat stability, emulsifying properties, foaming properties, gelling properties, water absorption capacity, oil absorption capacity, and calcium phosphate-solubilizing ability. In vitro physiological function studies of protein (α-lactoalbumin) indicated that the digestibility (ovalbumin) was improved and the inflammatory response (α-lactoalbumin) was suppressed by phosphorylation. Experiments with animals are necessary to evaluate the toxicity and physiological functions of phosphorylated proteins.  相似文献   
72.
高档的通信设备曾一度只能在办公环境中才能使用,然而现在这种情况已经改变,家庭中已经普遍具备了互连能力,许多家用电子设备现在通过Ipv6和其他技术已经具备了上网能力。随着宽带通信应用的增加,调制解调器、各种DSL接入复用器以及其他类似设备的安装已经遍及办公室和家庭,消费者可以方便获得价廉的通信设备。对于设备制造商来说,这些装置必须满足安全标准,如IEC60950(InternationalElectrotechnicalCommission第三版),它要求在与数据通信线连接的设备上实现电话网络高压电路的隔离。一般情况下,人们采用传统的电磁通信继电器来开关内…  相似文献   
73.
74.
75.
Any solution for an inverse heat conduction problem makes the estimation of surface temperature and surface heat flux worsen in the case where these values behave like a triangular shape change with time. In order to compensate for this defect, Monde and colleagues, who succeeded in obtaining analytical inverse solutions using the Laplace transform technique, introduce a new idea where these changes over the entire measurement time can be split into several parts depending on the behavior. Therefore, an approximate equation to trace the measured temperature change can be derived, resulting in good estimation of surface temperature and surface heat flux even in the case of the triangular shape change and sharp change. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(7): 630–638, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10117  相似文献   
76.
曹长娥 《焊管》1997,20(6):57-61
试验了彩色聚乙烯涂覆钢管的耐腐蚀性和耐气候性,由于聚乙烯涂层隔绝水的作用,聚乙烯涂覆钢管具有优良的耐腐蚀性能,电阻绝缘值和优良的机械性能。建立了一个新的方式去研究分析聚乙烯抗老化剂消耗和在聚乙烯中的扩散。用有效测定的方法定量地预测彩色聚乙烯涂覆层的寿命,应用这些分析结果,不仅可使新的有色聚乙烯涂覆钢管在恶劣腐蚀环境介质情况下具有高的耐腐蚀性,而且有长的耐气候性。  相似文献   
77.
We have studied a new timing circuit in which the input signal is put out at the same time as the clock signal. This is a key element for the realisation of Josephson vortex logic. We propose a new device structure which consists of two Josephson transmission lines connected by a resistor and a vortex trapping site (VTS). In this device a signal vortex is trapped in the VTS and it is repropagated to the output when the clock signal vortex propagates to the turning point. The quasistatic operation of this device is confirmed experimentally.  相似文献   
78.
A Chen-type correlation for flow boiling heat transfer of R-134a in horizontal tubes was modified taking into account the effect of tube diameter. The effect of tube diameter on flow boiling heat transfer coefficient was characterized by the Weber number in gas phase. Results showed that this correlation could be applied to a wide range of tube diameters (0.5–11-mm-ID). In addition, the dryout point and the heat transfer characteristics after the dryout point were also investigated based on the annular flow model. The proposed experimental expressions to predict both the dryout quality and the post-dryout heat transfer coefficient could also be applied to a wide range of tube diameter (0.5–11-mm-ID).  相似文献   
79.
An analytical method using Laplace transformation has been developed for one‐dimensional heat conduction. This method succeeded in explicitly deriving the analytical solution by which the surface temperature for the first kind of boundary condition can be well predicted. The analytical solutions for the surface temperature and heat flux are applied to the second and third of the boundary conditions. These solutions are also found to estimate the corresponding surface conditions with a high degree of accuracy when the surface conditions smoothly change. On the other hand, when these conditions erratically change such as the first derivative of temperature with time, the accuracy of the estimation becomes slightly less than that for a smooth condition. This trend in the estimation is similar irrespective of any kind of boundary condition. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(1): 29–41, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10069  相似文献   
80.
The deposition of gold ions from atomic force microscope cantilever tips onto bulk insulating substrates with nearby surface electrodes is discussed. Numerical models of the potential distribution are used to estimate potential barriers for the desorption process. These models indicate deposition height thresholds of 7-10 nm with the tip 20-25 nm from the metallic electrode edge over a KBr surface but greater than 20 nm high for InP/GaAs/InP substrates with a two-dimensional electron gas (2DEG) as the back electrode. Experimental results for the deposition of gold clusters over KBr surfaces near metal electrodes in ultra-high vacuum (UHV) are presented and show promising agreement with calculations of the deposition threshold heights. Deposition of clusters over InP is discussed for comparison and indicates similar trends.  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