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   128篇
  免费   4篇
  国内免费   1篇
电工技术   1篇
化学工业   38篇
机械仪表   2篇
建筑科学   2篇
能源动力   2篇
轻工业   24篇
水利工程   1篇
无线电   16篇
一般工业技术   27篇
冶金工业   13篇
原子能技术   5篇
自动化技术   2篇
  2023年   1篇
  2022年   2篇
  2021年   9篇
  2018年   3篇
  2016年   2篇
  2015年   3篇
  2014年   1篇
  2013年   10篇
  2012年   7篇
  2011年   9篇
  2010年   5篇
  2009年   9篇
  2008年   8篇
  2007年   9篇
  2006年   10篇
  2005年   4篇
  2004年   2篇
  2003年   5篇
  2002年   5篇
  2001年   1篇
  2000年   2篇
  1999年   1篇
  1998年   3篇
  1997年   2篇
  1995年   2篇
  1993年   1篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1986年   1篇
  1985年   3篇
  1983年   2篇
  1982年   4篇
  1981年   1篇
  1980年   1篇
  1978年   2篇
排序方式: 共有133条查询结果,搜索用时 15 毫秒
71.
Scope: Tomato is one of the most common crops worldwide and contains many beneficial compounds that improve abnormalities of lipid metabolism. However, the molecular mechanism underlying the effect of tomato on lipid metabolism is unclear. It has been commonly accepted that peroxisome proliferator‐activated receptor α (PPARα) is one of the most important targets for ameliorating abnormalities of lipid metabolism. Therefore, we focused on the activation of PPARα and attempted to detect active compounds activating PPARα in tomato. Methods and results: To identify such active compounds, we screened fractions of tomato extracts using PPARα luciferase reporter assay. One fraction, rechromatographed‐fraction eluted in 57 min (RF57), significantly increased PPARα reporter activity, in which a single compound is detected by LC/MS analysis. On the basis of LC/MS and NMR analyses, we determined the chemical structure of the active compound in RF57 as 9‐oxo‐10(E),12(E)‐octadecadienoic acid (9‐oxo‐ODA). The RF57 fraction significantly increased the mRNA expression levels of PPARα target genes involved in fatty acid oxidation and O2 consumption in mouse primary hepatocytes. Furthermore, RF57 inhibited cellular triglyceride accumulation in the hepatocytes. Conclusion: These findings suggest that tomatoes containing 9‐oxo‐ODA that acts on PPARα are valuable for ameliorating abnormalities of lipid metabolism.  相似文献   
72.
Dried squid were prepared at 4 or 40 °C and softened first in water and then in alkaline solution. The physicochemical and structural changes in the dried squid during the softening treatment were examined. A significantly higher wet weight was observed for the 4 °C‐dried squid during the softening treatment compared with the 40 °C‐dried squid. The rupture stress and rupture energy of the 40 °C‐dried squid were significantly higher than those of the 4 °C‐dried squid during the softening treatment. The sodium dodecyl sulphate polyacrylamide slab gel electrophoresis (SDS‐PAGE) pattern of the 4 °C‐dried squid was almost the same as that of raw squid. The SDS‐PAGE pattern of the 40 °C‐dried squid showed many fragments of lower molecular weight. After soaking in distilled water the SDS‐PAGE pattern of the 40 °C‐dried squid did not change significantly; however, the SDS‐PAGE pattern of the 4 °C‐dried squid became the same as that of the 40 °C‐dried squid. Histological analysis by light microscopy showed the formation of muscle fibre bundles in the 40 °C‐dried squid. A higher water permeation was observed among the muscle fibres of the alkali‐softened 4 °C‐dried squid when compared with the alkali‐softened 40 °C‐dried squid. Copyright © 2003 Society of Chemical Industry  相似文献   
73.
A heat-shrinkable multilayer film is widely employed as labels of plastic bottles. A new heat-shrinkable multilayer film without an adhesive layer was designed in this study. The interfacial adhesive strength between the layers was controlled to avoid layer separation. We assumed a polyethylene terephthalate glycol-modified (PETG)/styrene-co-butadiene block copolymer/PETG shrinkable film substitute as the general poly(ethylene terephthalate) (PET)/polystyrene/PET shrinkable film. The interlayer adhesive strength between the layers was retained for industrial utilization even after drawing. Additional polybutadiene (PB) infiltrated the butadiene layer in the microphase-separated structure. Further addition of PB could not infiltrate the butadiene layer. The excessive PB contents coexisted with the interface between the layers, as observed by transmission electron microscopy (TEM). The segregated PB enhanced the interfacial adhesive strength. We concluded that the selective distribution of adhesive functional materials along the interface could appropriately retain its adhesive strength.  相似文献   
74.
The large helical device (LHD), which is the world largest helical confinement system, is a national project serving Japanese fusion community. In LHD, experiments of 7000 shots are carried out for 250 proposals every year. Efficient experiment arrangement is required in order to carry out many collaborators’ proposal. Sometimes collaborators who are not familiar to LHD stay at NIFS only a few day to join the experiment. Issues are as follows: how to reduce collaborator's effort, how to reduce manager's effort to optimize the schedule; how to publicize plan and results of the experiment. We have developed web systems of virtual printer, experimental proposal and scheduling by using Ruby on Rails (RoR), which encapsulates relational data base (RDB) and AJAX. RDB enables to make tables by searching and sorting data with key words. Web servers are equipped in the virtual computer system in order to minimize efforts and cost of maintenance. The LHD web portal has been also developed in order to provide collaborators an efficient and intuitive interface to access the above systems, to take LHD information, and to use tools for LHD data analysis. The web systems have reduced collaborators’ and managers’ efforts significantly.  相似文献   
75.
The error probability for MPSK detection is expressed here as a sum of a familiar upper-bound approximation and a correction term which is well suited for numerical integration. An asymptotic expansion of the correction term is derived, from which simple and extremely tight upper and lower bounds are obtained. Relative errors in using these bounds and approximations of them are graphed for cases of practical interest.  相似文献   
76.
A simple and rapid method using refractive index high-performance liquid chromatography (RI-HPLC) was developed for the determination of polysorbates (PS) in processed foods. PS were extracted with ethyl acetate containing 5% methanol. The extract was cleaned up on a multimode cartridge (300 mg) and an Alumina-N cartridge (500 mg) to remove fats and food color. HPLC separation was performed on a C18 column (4.6 i.d. x 150 mm) with methanol as the mobile phase. The recoveries of PS80 from nine kinds of foods fortified at the levels 1-5 g/kg were 80-99%. The limit of quantitation for PS80 in foods was 0.10 g/kg. The proposed method was applied to Worcestershire sauce that was PS-positive by TLC, and PS was confirmed to be present as PS80 at the concentration of 0.13 g/kg.  相似文献   
77.
To realize larger‐capacity “Hybrid‐core transformer: HBT”, this research has assembled a 30‐MVA three‐phase trial HBT and evaluated the loss performances. The hybrid‐core consisting of the wound amorphous‐ and the stacked silicon steel‐cores, is expected having advantages of lower iron loss of the iron‐based amorphous material and the higher mechanical strength and saturation magnetic flux density of the silicon steels simultaneously. Three‐dimensional finite‐element method analysis revealed that the silicon steel core prevented over‐saturation of the amorphous core. The hybrid configuration enabled the design to have an approximately 10% higher magnetic flux density than configurations with only an amorphous core. We then assembled a prototype 30‐MVA three‐phase HBT designed on the basis of our investigation results. Operation tests demonstrated that the HBT has 62%‐reduced iron loss and 0.10%‐higher 50%‐loaded power efficiency from the conventional silicon steel core transformer.  相似文献   
78.
A simple mechanism to prolong the life cycle of the network by balancing nodes’ energy consumption is to rotate the active dominating set (DS) through a set of legitimate DSs. This paper proposes a novel adaptive clustering algorithm named HREF (Highest Remaining Energy First). In the HREF algorithm, cluster formation is performed cyclically and each node can declare itself as a cluster head autonomously if it has the largest residual energy among all its adjacent nodes. The performance effectiveness of the HREF algorithm is investigated and compared to the D-WCDS (Disjoint Weakly Connected Dominating Set) algorithm. In this paper, we assume the network topology is fixed and does not require sensor mobility. This allows us to focus on the impact of clustering algorithms on communication between network nodes rather than with the base station. Simulation results show that in the D-WCDS algorithm energy depletion is more severe and the variance of the node residual energy is also much larger than that in the HREF algorithm. That is, nodes’ energy consumption in the HREF algorithm is in general more evenly distributed among all network nodes. This may be regarded as the main advantage of the HREF adaptive clustering algorithm.  相似文献   
79.
Calcium pyrophosphate dihydrate (CPPD) crystals are formed locally within the joints, leading to pseudogout. Although the mobilization of local granulocytes can be observed in joints where pseudogout has manifested, the mechanism of this activity remains poorly understood. In this study, CPPD crystals were administered to mice, and the dynamics of splenic and peripheral blood myeloid cells were analyzed. As a result, levels of both granulocytes and monocytes were found to increase following CPPD crystal administration in a concentration-dependent manner, with a concomitant decrease in lymphocytes in the peripheral blood. In contrast, the levels of other cells, such as dendritic cell subsets, T-cells, and B-cells, remained unchanged in the spleen, following CPPD crystal administration. Furthermore, an increase in granulocytes/monocyte progenitors (GMPs) and a decrease in megakaryocyte/erythrocyte progenitors (MEPs) were also observed in the bone marrow. In addition, CPPD administration induced production of IL-1β, which acts on hematopoietic stem cells and hematopoietic progenitors and promotes myeloid cell differentiation and expansion. These results suggest that CPPD crystals act as a “danger signal” to induce IL-1β production, resulting in changes in course of hematopoietic progenitor cell differentiation and in increased granulocyte/monocyte levels, and contributing to the development of gout.  相似文献   
80.
Salmonella contamination of eggshells, egg contents, reusable egg trays, and various environmental samples was assessed. Although the overall Salmonella contamination rate from egg farms was low (3.2%), over a quarter (26.7%) of egg trays from farms and more than one third (36.7%) of trays from the market were contaminated. Salmonella strains isolated from reusable egg trays were analyzed by serotyping, antimicrobial susceptibility test and XbaI pulsed-field gel electrophoresis (PFGE) typing. Five serovars (S. Braenderup, S. Emek, S. Weltevreden, S. Stanley, and S. Derby) were isolated, and half of the strains assessed were found to be resistant to one or more of the six antimicrobial agents examined. The overall resistance rates to nalidixic acid, trimethoprim-sulfamethoxazole, tetracycline, and ampicillin were 40.7%, 36.0%, 26.7% and 3.5%, respectively. The PFGE types were matched against sample location and drug resistance. S. Braenderup PFGE type A2 (susceptible to all tested drugs) was isolated from all sample sites; PFGE type A2 (resistant to nalidixic acid) was isolated from Farm C and the market. S. Braenderup PFGE type A1 (resistant to four drugs) was isolated from Farms A and C. S. Weltevreden PFGE type C3 (susceptible to all tested drugs) was isolated from Farms A and B and type C4 (susceptible to all tested drugs) was isolated from Farm A and the market. The distribution of the related genotypes and resistance patterns of Salmonella in egg farms and the market indicate drug-resistant strains of Salmonella may be spread on reusable egg trays.  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