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   722128篇
  免费   20027篇
  国内免费   7475篇
电工技术   19010篇
技术理论   9篇
综合类   9256篇
化学工业   108392篇
金属工艺   33520篇
机械仪表   28124篇
建筑科学   23150篇
矿业工程   6485篇
能源动力   18439篇
轻工业   56840篇
水利工程   8927篇
石油天然气   18316篇
武器工业   1083篇
无线电   80234篇
一般工业技术   136752篇
冶金工业   115999篇
原子能技术   14639篇
自动化技术   70455篇
  2022年   6981篇
  2021年   10762篇
  2020年   7821篇
  2019年   8203篇
  2018年   17812篇
  2017年   18405篇
  2016年   15599篇
  2015年   11181篇
  2014年   16026篇
  2013年   32287篇
  2012年   25329篇
  2011年   35314篇
  2010年   29452篇
  2009年   30350篇
  2008年   30493篇
  2007年   31178篇
  2006年   22401篇
  2005年   22476篇
  2004年   19447篇
  2003年   18968篇
  2002年   17573篇
  2001年   16909篇
  2000年   15429篇
  1999年   15697篇
  1998年   35170篇
  1997年   24850篇
  1996年   19229篇
  1995年   14597篇
  1994年   12597篇
  1993年   12062篇
  1992年   8927篇
  1991年   8319篇
  1990年   8117篇
  1989年   7773篇
  1988年   7132篇
  1987年   6363篇
  1986年   6174篇
  1985年   6759篇
  1984年   6368篇
  1983年   5607篇
  1982年   5344篇
  1981年   5425篇
  1980年   5135篇
  1979年   5101篇
  1978年   4934篇
  1977年   5817篇
  1976年   7467篇
  1975年   4277篇
  1974年   4024篇
  1973年   4122篇
排序方式: 共有10000条查询结果,搜索用时 600 毫秒
91.
92.
93.
94.
This study aimed to evaluate the physicochemical characteristics and sensory attributes of beef burgers with the addition of pea fibre as a partial substitute of meat or fat. Three formulations were prepared: control (CON) – similar to the commercial formulation; fibre/less meat (FLM)—5% meat reduction and addition of 1% pea fibre; fibre/less fat (FLF)—7% fat reduction and addition of 1% pea fibre. Non-significant differences were obtained for pH, colour parameters (L* and b*), texture profile, cooking loss and size reduction among formulations. Moreover, sensory analysis with consumers of beef burgers did not indicate differences among the formulations for all the analysed attributes. Therefore, pea fibre is a promising partial replacer for meat and fat in beef burgers due to the preservation of technological parameters and sensory acceptance.  相似文献   
95.
The role of the following factors in the selection of technological bases for manufacturing is considered: the accessibility of the machined surfaces; their parameters and dimensional relationships; their position relative to the forces acting; and the uniformity of the margin distribution.  相似文献   
96.
Theoretical Foundations of Chemical Engineering - New research results, as well as those published earlier by the authors, on the synthesis of azo compounds based on nitroanilines obtained by the...  相似文献   
97.
The price of cobalt has increased by some 450% in the past two years, mainly due to increasing demand for lithium–ion batteries. With an official 2017 production of 64 kt, the Democratic Republic of Congo produces more than half of the world’s cobalt. African Copperbelt operations have traditionally focused on copper production; however, it has now become imperative to also consider cobalt recovery from these ores. A plethora of processing routes is possible. Most hydrometallurgical flowsheets recover cobalt from the raffinate of the low-grade copper solvent-extraction circuit. Downstream purification processes include sequential precipitation with a variety of reagents, solvent extraction, and ion exchange. Product choices include hydroxide, carbonate, sulfate, and metal cathode. This study assesses technical and economic advantages and limitations of various approaches to the hydrometallurgical processing of cobalt in an African context.  相似文献   
98.
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave...  相似文献   
99.
The proliferating need for sustainability intervention in food grain transportation planning is anchoring the attention of researchers in the interests of stakeholders and environment at large. Uncertainty associated with food grain supply further intensifies the problem steering the need for designing robust, cost-efficient and sustainable models. In line with this, this paper aims to develop a robust and sustainable intermodal transportation model to facilitate single type of food grain commodity shipments while considering procurement uncertainty, greenhouse gas emissions, and intentional hub disruption. The problem is designed as a mixed integer non-linear robust optimisation model on a hub and spoke network for evaluating near optimal shipment quantity, route selection and hub location decisions. The robust optimisation approach considers minimisation of total relative regret associated with total cost subject to several real-time constraints. A version of Particle Swarm Optimisation with Differential Evolution is proposed to tackle the resulting NP-hard problem. The model is tested with two other state-of the art meta-heuristics for small, medium, and large datasets subject to different procurement scenarios inspired from real time food grain operations in Indian context. Finally, the solution is evaluated with respect to total cost, model and solution robustness for all instances.  相似文献   
100.
Fang  Zhiwei  Xing  Qiyu  Fernandez  Desiree  Zhang  Xiao  Yu  Guihua 《Nano Research》2020,13(5):1179-1190

Two-dimensional (2D) nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004, due to their intriguing physicochemical properties and wide-ranging applications in catalysis, energy-related devices, electronics and optoelectronics. To maximize the potential of 2D nanomaterials for their technological applications, controlled assembly of 2D nanobulding blocks into integrated systems is critically needed. This mini review summarizes the reported strategies of 2D materials-based assembly into integrated functional nanostructures, from in-situ assembly method to post-synthesis assembly. The applications of 2D assembled integrated structures are also covered, especially in the areas of energy, electronics and sensing, and we conclude with discussion on the remaining challenges and potential directions in this emerging field.

  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