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   2530篇
  免费   96篇
  国内免费   14篇
电工技术   84篇
综合类   4篇
化学工业   604篇
金属工艺   85篇
机械仪表   94篇
建筑科学   67篇
矿业工程   2篇
能源动力   204篇
轻工业   250篇
水利工程   30篇
石油天然气   31篇
无线电   279篇
一般工业技术   455篇
冶金工业   207篇
原子能技术   16篇
自动化技术   228篇
  2024年   5篇
  2023年   35篇
  2022年   55篇
  2021年   116篇
  2020年   78篇
  2019年   76篇
  2018年   113篇
  2017年   88篇
  2016年   97篇
  2015年   68篇
  2014年   89篇
  2013年   249篇
  2012年   173篇
  2011年   164篇
  2010年   118篇
  2009年   108篇
  2008年   96篇
  2007年   80篇
  2006年   75篇
  2005年   54篇
  2004年   48篇
  2003年   56篇
  2002年   45篇
  2001年   45篇
  2000年   48篇
  1999年   31篇
  1998年   68篇
  1997年   45篇
  1996年   38篇
  1995年   38篇
  1994年   20篇
  1993年   30篇
  1992年   7篇
  1991年   15篇
  1990年   13篇
  1989年   12篇
  1988年   23篇
  1987年   21篇
  1986年   15篇
  1985年   12篇
  1984年   15篇
  1983年   7篇
  1982年   5篇
  1981年   5篇
  1980年   4篇
  1979年   7篇
  1978年   4篇
  1976年   6篇
  1975年   6篇
  1973年   3篇
排序方式: 共有2640条查询结果,搜索用时 15 毫秒
61.
Variability and sensitivity of a portable electronic nose (32 sensors) was assessed by considering different variables for measurement (i.e., reference, standard, first and second purges, sample draw time, waiting time for the volatiles released in the headspace, and mass of sample or headspace volume of the jar containing sample). In this study, dried date-pits were used a model sample. The highest stability was achieved when both reference and standard (i.e., dried date-pits, no heating treatment) were used before test sample measurement. Higher sample draw time more than 10 s significantly decreased the stability, whereas optimum second purge was observed at 50 s. Optimum time to generate volatile was observed as 24 h. A sample of 100 g increased the signal intensity compared to the 50 g sample for the 60°C and 100°C treated samples, while an opposite trend was observed for the 150°C treated sample. Finally, the responses of volatile components in date-pits heated at different temperatures (60°C, 100°C, and 150°C) were measured using the optimum operating conditions. Principal component analysis explored the relationships between the volatile features and classified date-pits heated at different temperatures. The results showed that an electronic nose was able to classify date-pits based on their volatile components generated by different degrees of heating (93.3% accuracy).  相似文献   
62.
Multimedia Tools and Applications - Adaptive Media Playout (AMP) controls adapt playout rate to prevent buffer outage and to reduce delay in playout. Most AMP techniques use buffer fullness or its...  相似文献   
63.
Microsystem Technologies - This study considers a novel compound fast fractional integral sliding mode control and adaptive PI control (APIFFOISMC) of a MEMS gyroscope. MEMS gyroscope has been...  相似文献   
64.
Khare  Kshitij  Oh  Sang-Yun  Rahman  Syed  Rajaratnam  Bala 《Machine Learning》2019,108(12):2061-2086
Machine Learning - Covariance estimation for high-dimensional datasets is a fundamental problem in machine learning, and has numerous applications. In these high-dimensional settings the number of...  相似文献   
65.
Most of the applications related to security and biometric rely on skin region detection such as face detection, adult 3D objects filtering, and gesture recognition. In this paper, we propose a robust method for skin detection on 3D coloured point clouds. Then, we extend this method to solve the problem of 3D face detection. To do so, we construct a weighted graph from initial coloured 3D point clouds. Then, we present a linear programming algorithm using a predictive model based on a data mining approach to classify and label graph vertices as skin and non-skin regions. Moreover, we apply some refinement rules on skin regions to confirm the presence of a face. Furthermore, we demonstrate the robustness of our method by showing and analysing some experimental results. Finally, we show that our method deals with many data that can be represented by a weighted graph such as 2D images and 3D models.  相似文献   
66.
67.
68.
69.
University students spend most of their time in classrooms, mostly in a sitting position. Prolonged sitting on ill-fitted furniture and the resulting bad posture is making students suffer from different musculoskeletal disorders (MSDs). This study evaluates the potential mismatch between furniture dimensions and anthropometric measurements. To determine potential mismatch, 13 anthropometric measurements of 550 students and 11 dimensions of two types of classroom furniture (mounted-desktop and chair-with-table) were measured and then compared. Additionally, chi-square test was performed to compare the relation between anthropometry and relevant furniture dimensions. Results showed that a significant number of mismatches emerged between anthropometric measurements and furniture dimensions. For both types of furniture, seat height was too high and seat depth was too deep. Moreover, for mounted desktop, desk height is almost appropriate for all students whereas for chair and table, it was too high for the males. These circumstances may lead to increase discomfort and increase MSDs problems among all students. It can be concluded that the dimensions of both types of classroom furniture were not appropriate for users according to anthropometric measurements. This analysis recommends the measurements of furniture dimensions based on participants’ anthropometric measurements to avoid or minimise discomfort and MSDs problems.  相似文献   
70.
High‐pressure treatment, which is an effective means of enhancing enzymatic reactions, was implemented during beer mashing to increase the production yield of fermentable sugar (FS). The malt solution was heated (62, 67, and 72°C) under pressure [0.1 (1 atm), 2, 50 and 100 MPa], and the FS was measured. The amount of FS reached an equilibrium level, which was the highest at 67°C and at 2 MPa. The pressures were 2, 50, 100, and 0.1 MPa in decreasing order of FS amount at 67°C. The temperatures were 67, 72 and 62°C in decreasing order of FS amount at 2 MPa. With a mechanistic approach, only the effect of pressure on gelatinization was analysed. The gelatinization degrees were also higher at pressures higher than 0.1 MPa. This observation highlights the positive effect (increasing the FS yield) of high‐pressure treatment on beer mashing. Copyright © 2015 The Institute of Brewing & Distilling  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