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   866470篇
  免费   11351篇
  国内免费   2231篇
电工技术   15996篇
综合类   769篇
化学工业   134582篇
金属工艺   33943篇
机械仪表   26875篇
建筑科学   21338篇
矿业工程   4983篇
能源动力   22335篇
轻工业   75058篇
水利工程   9257篇
石油天然气   16386篇
武器工业   52篇
无线电   99104篇
一般工业技术   170359篇
冶金工业   155041篇
原子能技术   18474篇
自动化技术   75500篇
  2021年   7315篇
  2019年   6994篇
  2018年   11874篇
  2017年   12121篇
  2016年   12813篇
  2015年   8531篇
  2014年   14190篇
  2013年   40337篇
  2012年   22695篇
  2011年   31253篇
  2010年   24892篇
  2009年   27812篇
  2008年   28792篇
  2007年   28682篇
  2006年   25195篇
  2005年   22942篇
  2004年   22177篇
  2003年   21628篇
  2002年   20908篇
  2001年   20569篇
  2000年   19424篇
  1999年   19711篇
  1998年   45606篇
  1997年   33223篇
  1996年   25994篇
  1995年   20166篇
  1994年   18124篇
  1993年   17631篇
  1992年   13520篇
  1991年   12956篇
  1990年   12730篇
  1989年   12303篇
  1988年   11812篇
  1987年   10415篇
  1986年   10171篇
  1985年   11942篇
  1984年   11026篇
  1983年   10091篇
  1982年   9263篇
  1981年   9301篇
  1980年   8887篇
  1979年   8932篇
  1978年   8633篇
  1977年   9828篇
  1976年   12707篇
  1975年   7579篇
  1974年   7249篇
  1973年   7208篇
  1972年   6121篇
  1971年   5600篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
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   
94.
95.
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   
96.
In the future, hydrogen will be an important energy carrier and industrial raw material. Catalytic steam reforming of bio-oils is a promising and economically viable technology for hydrogen production. However, during the reforming process, the catalysts are rapidly deactivated due to coke formation and sintering. Thus, maintaining the activity and stability of catalysts is the key issue in this process. Optimized operation conditions could extend the catalyst lifetime by affecting the coke morphology or promoting coke gasification. This article summarizes the recent developments in the field of catalytic steam reforming of bio-oils, focusing on the operation conditions, the properties of the catalysts, and the effects of the catalyst supports. The expected insights into the catalytic steam reforming of bio-oils will provide further guidance for hydrogen production from bio-oils.  相似文献   
97.
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with...  相似文献   
98.
At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st  相似文献   
99.
Debittered trub (brewing waste) is an important source of protein source (70.26%). Trub and whey protein were used for 5% protein enrichment of ice cream frozen by liquid nitrogen. Three formulations were elaborated: ice cream standard (ICS), ice cream with whey protein (ICW) and ice cream with trub (ICT). Chemical composition, rheological properties, texture, overrun, melting rate, scanning electron microscopy and a sensorial test were performed. Results showed that ICT presented a higher viscosity, obtained on the upward curve up to 6.76 Pa s−1, consistency index (22.96 (Pa s−1)n), hysteresis area (140.40 mPa s−1) and hardness (31113.33 g) but a lower melting rate (0.38 g min−1), overrun (13.92%) and sensorial acceptability than the other formulations. The addition of trub debittered for protein enrichment improved ice cream properties and demonstrated that it could be used as a food ingredient.  相似文献   
100.
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   
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