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   1131篇
  免费   83篇
  国内免费   10篇
电工技术   28篇
综合类   10篇
化学工业   260篇
金属工艺   25篇
机械仪表   38篇
建筑科学   43篇
矿业工程   5篇
能源动力   40篇
轻工业   43篇
水利工程   7篇
石油天然气   22篇
武器工业   13篇
无线电   181篇
一般工业技术   241篇
冶金工业   67篇
原子能技术   4篇
自动化技术   197篇
  2024年   3篇
  2023年   23篇
  2022年   51篇
  2021年   58篇
  2020年   55篇
  2019年   55篇
  2018年   60篇
  2017年   48篇
  2016年   58篇
  2015年   48篇
  2014年   38篇
  2013年   67篇
  2012年   58篇
  2011年   73篇
  2010年   52篇
  2009年   57篇
  2008年   45篇
  2007年   47篇
  2006年   40篇
  2005年   24篇
  2004年   19篇
  2003年   32篇
  2002年   19篇
  2001年   13篇
  2000年   18篇
  1999年   10篇
  1998年   21篇
  1997年   19篇
  1996年   14篇
  1995年   10篇
  1994年   10篇
  1993年   14篇
  1992年   9篇
  1991年   2篇
  1990年   6篇
  1989年   4篇
  1988年   3篇
  1987年   2篇
  1986年   4篇
  1985年   5篇
  1984年   7篇
  1983年   4篇
  1982年   5篇
  1981年   4篇
  1977年   2篇
  1975年   2篇
  1973年   1篇
  1971年   1篇
  1969年   1篇
  1965年   1篇
排序方式: 共有1224条查询结果,搜索用时 593 毫秒
31.
We present in this paper a fuzzy clustering algorithm which can handle spatially constraint problems often encountered in pattern recognition. The proposed method is based on the notions of hyperplanes, the fuzzy c-means, and spatial constraints. By adding a spatial regularizer into the fuzzy hyperplane-based objective function, the proposed method can take into account additionally important information of inherently spatial data. Experimental results have demonstrated that the proposed algorithm achieves superior results to some other popular fuzzy clustering models, and has potential for cluster analysis in spatial domain.  相似文献   
32.
Reducing noise in medical images has been an important issue of research and development for medical diagnosis, patient treatment, and validation of biomedical hypotheses. Noise inherently exists in medical and biological images due to the acquisition and transmission in any imaging devices. Being different from image enhancement, the purpose of image restoration is the process of removing noise from a degraded image in order to recover as much as possible its original version. This paper presents a statistically supervised approach for medical image restoration using the concept of multiple-point geostatistics. Experimental results have shown the effectiveness of the proposed technique which has potential as a new methodology for medical and biological image processing.  相似文献   
33.
Lecontite, (NH4)Na(SO4).2H2O, was synthesised at room temperature in high purity compared to earlier work with a minor impurity of mascagnite, (NH4)2SO4. Rietveld refinement of the XRD results confirmed the crystal structure and unit cell dimensions as published earlier. Raman and Infrared spectroscopy, in conjunction with factor group analysis, resulted in a complex pattern of overlapping sulphate, NH and OH modes. The NH modes υ1 was observed around 2880 cm−1, υ2 around 1700 cm−1 overlapping with water OH-bending modes, υ3 around 3300 cm−1 overlapping with water OH-stretching modes around 3023, 3185 and 3422 cm−1, and υ4 around 1432, 1447 and 1462 cm−1. The sulphate group in the crystal structure displays a decrease in symmetry from Td as evidenced by the activation of the ν1 mode at 982 cm−1 and the ν2 mode around 452 cm−1 in the Infrared spectrum. The υ3 mode shows clear splitting in the infrared spectra with a strong band at 1064 cm−1 accompanied by two shoulders at 1107 and 1139 cm−1. The Raman spectra show three weak bands at 1068, 1109 and 1135 cm−1 with a shoulder at 1155 cm−1. Similar splitting was observed for the υ4 mode around 611 and 632 cm−1 in the Infrared and Raman spectra, respectively.  相似文献   
34.
赵团  张俊卿  何青明 《稀土》2006,27(1):47-49
化选矿经硫酸浸出,在合适的酸度、温度、反应时间条件下,稀土浸出率为90%。  相似文献   
35.
36.
37.
We consider the problem of identifying unknown nonstationary piecewise linear parameters for a linear regression model. A new algorithm is proposed that allows, in the case of a number of assumptions on the elements of the regressor, to provide an estimate of unknown non-stationary parameters. We analyze in detail the case with two unknown parameters, which makes it possible to understand the main idea of the proposed approach. We also consider a generalization to the case of an arbitrary number of parameters. We give an example of computer simulation that illustrates the efficiency of the proposed approach.  相似文献   
38.
39.
European Journal of Wood and Wood Products - The fundamental material properties of coconut wood cross-laminated timber (CLT) were experimentally evaluated with a focus on the effect of the...  相似文献   
40.
Apolipoprotein A-V encoded by apolipoprotein 5 (APOA5) gene plays an important role in lipid metabolism, especially in the regulation of plasma triglycerol levels. The study aimed to evaluate the association of the APOA5-rs662799 polymorphism with dyslipidemia in Vietnamese children and the potential modification of obesity-related traits (body mass index, waist circumference, hip circumference, and waist-to-hip ratio) on this association. A case–control study was conducted with a total of 154 dyslipidemia cases and 389 controls at the age of 6 to 10 recruited at 31 primary schools in Hanoi city of Vietnam. Genotype for APOA5-rs662799 polymorphism was determined by the restriction fragment length polymorphism analysis. The association of APOA5-rs662799 polymorphism with dyslipidemia adjusting for age, sex, residence, and obesity-related traits was analyzed by binary logistic regression analysis. The results showed that in comparison with T/T and T/C carriers, the C/C carriers had a higher concentration of serum TAG in cases (p =0.049). Carriers of the C allele (C/C + T/C) had higher risk for developing dyslipidemia and hypertriglyceridemia than subjects with T/T genotype (odds ratio, OR = 1.7, p =0.0062 and OR = 1.6, p = 0.026, respectively). The association remained significant after adjusting for age, gender, residence, and obesity status (OR = 1.75, p = 0.006 and OR = 1.53, p = 0.049, respectively) or other obesity-related traits. The study suggested that the APOA5-rs662799 polymorphism may be a determinant of dyslipidemia and hypertriglyceridemia in Vietnamese children, independent of obesity-related traits.  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