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   207篇
  免费   7篇
  国内免费   1篇
电工技术   7篇
化学工业   34篇
金属工艺   6篇
机械仪表   4篇
建筑科学   7篇
能源动力   7篇
轻工业   34篇
水利工程   2篇
石油天然气   1篇
无线电   6篇
一般工业技术   25篇
冶金工业   46篇
自动化技术   36篇
  2022年   7篇
  2021年   9篇
  2020年   3篇
  2019年   1篇
  2018年   11篇
  2017年   4篇
  2016年   7篇
  2015年   7篇
  2014年   12篇
  2013年   12篇
  2012年   14篇
  2011年   18篇
  2010年   8篇
  2009年   10篇
  2008年   6篇
  2007年   7篇
  2006年   9篇
  2005年   2篇
  2004年   5篇
  2003年   6篇
  2002年   3篇
  2001年   5篇
  2000年   3篇
  1999年   3篇
  1998年   12篇
  1997年   10篇
  1996年   3篇
  1995年   1篇
  1994年   4篇
  1993年   4篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1983年   2篇
  1982年   1篇
  1976年   2篇
  1957年   1篇
排序方式: 共有215条查询结果,搜索用时 15 毫秒
1.
Thraustochytrids, marine protists whose dominant genera are Thraustochytrium and Schizochytrium, belong to the kingdom Chromista and are known as an industrial source of DHA. We describe here that thraustochytrid strain KH105, isolated as a DHA producer, also accumulates significant levels of β-carotene and xanthophylls including canthaxanthin and astaxanthin. A4-d cultivation using a medium composed of 10% glucose and less than 0.3% of nitrogen sources in a half-concentration of seawater gave an astaxanthin production up to 6.1 mg/L, and canthaxanthin content reached more than 10 mg/L under conditions where a higher concentration of nitrogen sources (6%) was employed. It might be advantageous in mass production systems for these carotenoids to be extracted readily by simply suspending the cells with organic solvents such as acetone and chloroform. Analyses on the morphological and life history features of the KH105 strain revealed that it belongs to the genus Schizochytrium. This particular species of thraustochytrids is thus considered to be a promising source of xanthophylls as well as DHA for use in the food industry.  相似文献   
2.
Journal of Infrared, Millimeter, and Terahertz Waves - Millimeter waves (MMW) absorbed by skin or cornea may induce damage by heat. We have developed a 60 GHz MMW exposure-induced eye...  相似文献   
3.
4.
5.
Calibration samples for the Barkhausen noise (BN) method were produced with laser processing. A planet gear wheel used for production quality control was subjected to laser irradiation to verify the BN sensor output. Different samples were found to respond similarly to the laser processing although the laser parameters needed to be adjusted for different surface qualities separately. The surface optimization for laser processing was studied with different surface qualities of samples. The ground surface was compared with a sandblasted and vibratory ground surface. The ground and sandblasted surfaces were both amenable to the laser processing whereas the vibratory grinding process created inhomogeneous surfaces for laser beam absorption. Laser processing was found to produce uniform changes in the residual stress values in two perpendicular measuring directions. The root mean square value of the BN voltage signal exhibited linear correlations with the values of the residual stress and surface hardness.  相似文献   
6.
7.
An unusual clinical presentation of a patient with neuronal intestinal dysplasia is presented. A 46-year-old male noted a palpable mass in the right lower quadrant of his abdomen for two months. A computed axial tomographic scan showed a thickened wall of the cecum with a tumor-like appearance. The excised specimen consisted of a mass caused by the thickened, edematous wall of the dilated cecum and appendix. The wall of the cecum and appendix measured up to 2.5 and 0.8 cm, respectively, in thickness. Microscopic studies showed extensive hyperplasia and hypertrophy of the ganglia and nerve plexuses and hypertrophy of the muscularis propria, consistent with neuronal intestinal dysplasia.  相似文献   
8.
A protocol for the analysis of the positional distribution of fatty acids (FA) in solid triacylglycerols (TAG) was developed using sn-1(3) selective alcoholysis catalyzed by immobilized Candida antarctica lipase B (CALB). One part by weight of solid fat and ten parts by weight of ethanol (99.5 %) were warmed to liquefy the fat. After adding 0.44 parts by weight of CALB, the mixture was shaken at 50 °C for 10 min then at 30 °C for 2.8 h. The recovery of 2-MAG after the 3-h transesterification reaction was ca. 85 % of the maximum theoretical yield (33 mol%), with the loss of 15 % attributable to the acyl migration from sn-2 to sn-1(3). The recovery was similar to that of the solvent-free alcoholysis of structured lipids, 1,3-dipalmitoyl, 2-oleoyl glycerol and 1,3-dioleoyl, 2-palmitoyl glycerol, conducted at 30 °C for 3 h. In contrast, the acyl migration from sn-1(3) to sn-2 was hardly observed. Because the detected acyl migration was only in the direction of sn-2 to sn-1(3), and not vice versa, it is proposed to determine the FA composition of the sn-2 position of TAG by the gas chromatographic analysis of 2-MAG fraction recovered from the enzymatic reaction mixture, and the FA composition of sn-1(3) position by a mass balance using the FA composition of TAG and of the sn-2 position as inputs. The procedure was successfully applied to palm oil and shea butter, and docosahexaenoic acid (DHA)-rich single cell oil from Aurantiochytrium sp. KH105 for the first time.  相似文献   
9.
Residual stress of case-hardened steel samples is predicted in this paper with the linear multivariable regression model. The development of the prediction model is based on the huge set of features calculated from the Barkhausen noise measurement signal among which the most suitable ones are chosen. The selection uses a genetic algorithm with leave-multiple-out cross-validation in the objective function. The original feature set contains collinear features that make the selection task even more complex. Thus a feature elimination procedure based on the successive projections algorithm is studied in this paper. Also the standard genetic algorithm is slightly modified to better serve the feature selection task. The obtained results are good showing that the proposed procedures suit well for residual stress predictions. Also the applied feature elimination procedure is applicable and can be safely used to reduce the dimensionality of the selection problem.  相似文献   
10.
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