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   563683篇
  免费   11948篇
  国内免费   3360篇
电工技术   12005篇
技术理论   3篇
综合类   3202篇
化学工业   85106篇
金属工艺   22110篇
机械仪表   17584篇
建筑科学   15620篇
矿业工程   3400篇
能源动力   15620篇
轻工业   49638篇
水利工程   5991篇
石油天然气   11836篇
武器工业   416篇
无线电   64703篇
一般工业技术   106321篇
冶金工业   105204篇
原子能技术   10959篇
自动化技术   49273篇
  2022年   4664篇
  2021年   6926篇
  2020年   4985篇
  2019年   5682篇
  2018年   9153篇
  2017年   9018篇
  2016年   9088篇
  2015年   7218篇
  2014年   11374篇
  2013年   26442篇
  2012年   17315篇
  2011年   23054篇
  2010年   18374篇
  2009年   19849篇
  2008年   20381篇
  2007年   19817篇
  2006年   17484篇
  2005年   15931篇
  2004年   14703篇
  2003年   14340篇
  2002年   13541篇
  2001年   13623篇
  2000年   12650篇
  1999年   13537篇
  1998年   33539篇
  1997年   23465篇
  1996年   17988篇
  1995年   13485篇
  1994年   11662篇
  1993年   11221篇
  1992年   8143篇
  1991年   7590篇
  1990年   7388篇
  1989年   7110篇
  1988年   6550篇
  1987年   5817篇
  1986年   5696篇
  1985年   6299篇
  1984年   5928篇
  1983年   5195篇
  1982年   4923篇
  1981年   4986篇
  1980年   4726篇
  1979年   4620篇
  1978年   4419篇
  1977年   5345篇
  1976年   6979篇
  1975年   3803篇
  1974年   3554篇
  1973年   3677篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
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   
62.
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   
63.
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   
64.
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   
65.
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   
66.

Surface integrity characterization of manufactured component is very important as it significantly affects the in-service performance of the component. Till now, surface integrity was evaluated using conventional measurement technique like microhardness tester, X-ray diffraction, optical microscopy and surface roughness tester. But, this technique being laboratory based cannot be used for in-service monitoring of the surface integrity. The present study focuses on the characterization of surface integrity upon electric discharge machined sample using non-destructive magnetic Barkhausen noise technique. Electric discharge machining was performed in die-sinking mode on die steel using copper–tungsten electrode (negative polarity). Experiment was performed by selecting different levels of peak current, gap voltage and pulse on time. Surface integrity characteristics like microhardness change, residual stress, microstructural alteration and surface roughness were analysed using microhardness tester, X-ray diffraction, optical microscopy and surface roughness tester, respectively, and were then correlated with magnetic parameter like root mean square value and peak value obtained from Barkhausen noise signal. The results show a good correlation between magnetic parameter (RMS and Peak value) of Barkhausen noise with the microhardness and surface roughness of the machined sample.

  相似文献   
67.
Yan  Jing  Zhu  Rongying  Wu  Fan  Zhao  Ziyin  Ye  Huan  Hou  Mengying  Liu  Yong  Yin  Lichen 《Nano Research》2020,13(10):2706-2715
Nano Research - Insufficient intratumoral penetration greatly hurdles the anticancer performance of nanomedicine. To realize highly efficient tumor penetration in a precisely and spatiotemporally...  相似文献   
68.
69.
70.
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