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   66篇
  免费   2篇
电工技术   2篇
化学工业   23篇
金属工艺   1篇
机械仪表   2篇
轻工业   11篇
水利工程   2篇
无线电   2篇
一般工业技术   13篇
冶金工业   4篇
自动化技术   8篇
  2022年   4篇
  2021年   12篇
  2019年   2篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2015年   1篇
  2014年   1篇
  2013年   4篇
  2012年   1篇
  2011年   2篇
  2010年   5篇
  2009年   3篇
  2008年   1篇
  2007年   2篇
  2006年   4篇
  2004年   3篇
  2003年   3篇
  2002年   1篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1995年   1篇
  1994年   2篇
  1990年   1篇
  1989年   1篇
  1982年   1篇
  1977年   1篇
  1972年   2篇
  1969年   1篇
  1966年   1篇
  1959年   1篇
排序方式: 共有68条查询结果,搜索用时 562 毫秒
1.
Multimedia data from two probability-based exposure studies were investigated in terms of how missing data and measurement-error imprecision affected estimation of population parameters and associations. Missing data resulted mainly from individuals'refusing to participate in certain measurement activities, rather than from field or laboratory problems; it suggests that future studies should focus on methods for maximizing participation rates. Measurement error variances computed from duplicate-sample data were small relative to the inherent variation in the populations; consequently, adjustments in nonparametric percentile estimates to account for measurement imprecision were small. Methods of adjustment based on lognormality assumptions, however, appeared to perform poorly.  相似文献   
2.
The design and synthesis of heparin mimetics with high anticancer activity but no anticoagulant activity is an important task in medicinal chemistry. Herein, we present the efficient synthesis of five Glc-GlcA-Glc-sequenced and one Glc-IdoA-Glc-sequenced non-glycosaminoglycan, heparin-related trisaccharides with various sulfation/sulfonylation and methylation patterns. The cell growth inhibitory effects of the compounds were tested against four cancerous human cell lines and two non-cancerous cell lines. Two d -glucuronate-containing tetra-O-sulfated, partially methylated trisaccharides displayed remarkable and selective inhibitory effects on the growth of ovary carcinoma (A2780) and melanoma (WM35) cells. Methyl substituents on the glucuronide unit proved to be detrimental, whereas acetyl substituents were beneficial to the cytostatic activity of the sulfated derivatives.  相似文献   
3.
4.
A novel electrophoretic alpha-lactalbumin (alpha-la) variant was detected in the Italian water buffalo breed. The isoelectric point of the variant, labelled A, was lower than the most frequent variant B. It presented an allelic frequency of 0.5% compared with the 97.1% of the BB allele. From Liquid Chromatography-Electrospray Ionization/Mass spectrometry, the molecular mass of the two alpha-la A and B variants were measured as 14,235.1+/-0.8 and 14,236.1+/-0.9 Da, respectively. The two proteins were sequenced and differentiated from one another by a single amino acid substitution, Asn45(B)-->Asp45(A). As this amino acid substitution altered the N-glycosylation sequence consensus Asn45-X-Ser46 it may be deduced that the protein glycosylation level of the alpha-la A would decrease.  相似文献   
5.
A comparison study of three different multi-component Lattice Boltzmann models is carried out to explore their capability of describing binary immiscible fluid systems. The Shan–Chen pseudo potential model, the Oxford free energy model and the colour gradient model are investigated using the multi-relaxation time scheme (MRT) algorithm to study the flow of binary immiscible fluids. We investigate Poiseuille flow of layered immiscible binary fluids and capillary fingering phenomena and evaluate the results against analytical solutions. In addition, we examine the capability of the various models to simulate fluids with significant viscosity and density contrast and suitable interface thickness. This is of great importance for large scale flow in porous media applications, where it is important to minimise the interfacial thickness from a computational point of view. We find that the Shan–Chen model can simulate high density ratios up to 800 for binary fluids with the same viscosity. Imposing a viscosity contrast will lead to highly diffusive interfaces in the Shan–Chen model and therefore this will affect significantly the numerical stability. The Free Energy model and the colour gradient model have similar capabilities on this point: they can simulate binary fluids having the same density but with significant viscosity contrast. This is of great importance to study the flow of water, supercritical CO2 and oil in porous media, for CO2 storage and Enhanced Oil Recovery (EOR) operations.  相似文献   
6.
The gross chemical composition and functional properties (solubility, emulsifying and foaming properties) of different amaranth protein preparations were studied in model systems and were compared to those of casein and soy protein isolates. Preparations of alkaline-soluble total protein, albumin, globulin, and glutelin-like alkaline-soluble residual protein were produced from two different types of defatted amaranth meals by extraction and fractionation. Although similarity can be shown between protein patterns of legumes (including soy) and amaranth, the emulsifying and foaming properties of amaranth protein preparations are relatively poor in comparison to the reference proteins, except foaming properties of albumin preparations. Nevertheless, taking in mind that these properties depend on interactions with other food components and textural requirements of individual food products, the amaranth protein preparations may be treated as potential protein sources and food ingredients.  相似文献   
7.
This paper deals with the design of car bodies from the first sketches to the master model, ie to the last stage before mass manufacture. Close scrutiny of the various steps needed in drawing, control and construction make it possible to determine which of them can be replaced by modern automatic procedures.  相似文献   
8.
Hernia is a defect of the abdominal wall. Treatment is principally surgical mesh implantation. Non‐degradable surgical meshes produce numerous complications and side‐effects such as inflammatory response, mesh migration and chronic pain. In contrast, the biodegradable, poly (vinyl alcohol) (PVA) based polymers have excellent chemical, mechanical and biological properties and after their degradation no chronic pain can be expected. The toxicology of PVA solution and fibers was investigated with Human dermal fibroblast‐ Adult cell line. Implantation tests were observed on long‐term contact (rat) and large animal (swine) models. To measure the adhesion formation, Diamond and Vandendael score were used. Macroscopical and histological responses were graded from the samples. In vitro examination showed that PVA solution and fibers are biocompatible for the cells. According to the implantation tests, all samples were integrated into the surrounding tissue, and there was no foreign body reaction. The average number of adhesions was found on the non‐absorbable suture line. The biocompatibility of the PVA nanofiber mesh was demonstrated. It has a non‐adhesive, non‐toxic and good quality structure which has the potential to be an alternative solution for the part of the hernia mesh.  相似文献   
9.
A facility location allocation model for reusing carpet materials   总被引:1,自引:0,他引:1  
Re-using the huge quantities of carpet waste that are yearly generated has become a must. A facility location–allocation model for the collection, preprocessing and redistribution of carpet waste is presented. This model differs from other mathematical models for supporting the design of the logistic structure of reuse networks among others in a completely free choice of the locations for preprocessing and in explicitly taking into account depreciation costs. Two applications of the model, one in Europe and one in the United States of America, are described.  相似文献   
10.
This study provides insights into consumers' decision-making when purchasing green wine, and the market perceptions regarding green wines in terms of price, quality, trendiness and acceptance of green terms such as ‘carbon neutral'. Data were collected from 191 South African wine consumers through an online survey. Although greening is indeed recognised by the consumer as a social responsibility image cue that shapes their choices, its importance is relatively low compared with that of other conventional cues. Some of the most common green marketing strategies, such as green certification, were of relatively low significance to the consumer. Green wines were generally regarded as trendy and fashionable but are unlikely to play a significant role in the pricing of these wines. Consumer demographics are an important determinant regarding the relevance of greening as a purchasing consideration, with females attributing more significance to this purchasing factor. This study is of value to academic researchers and wine industry practitioners alike. It contributes to the knowledge base by providing new perspectives on consumer perception of green wines, the social responsibility aspects and its marketing, and is the first of its kind conducted in the South African environment.  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