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   107篇
  免费   9篇
电工技术   4篇
化学工业   35篇
金属工艺   6篇
机械仪表   7篇
矿业工程   1篇
能源动力   2篇
轻工业   7篇
无线电   18篇
一般工业技术   17篇
冶金工业   15篇
原子能技术   1篇
自动化技术   3篇
  2023年   1篇
  2022年   4篇
  2021年   4篇
  2020年   2篇
  2019年   2篇
  2018年   1篇
  2017年   3篇
  2016年   8篇
  2015年   2篇
  2014年   7篇
  2013年   8篇
  2012年   4篇
  2011年   2篇
  2010年   3篇
  2009年   3篇
  2008年   5篇
  2007年   6篇
  2006年   3篇
  2005年   5篇
  2004年   5篇
  2003年   3篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1999年   3篇
  1998年   7篇
  1997年   5篇
  1996年   2篇
  1994年   3篇
  1987年   1篇
  1983年   2篇
  1982年   1篇
  1980年   2篇
  1972年   1篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
排序方式: 共有116条查询结果,搜索用时 15 毫秒
31.
To allow detection of meat from the most popular game species in Poland, we developed a PCR-based method for identification of roe deer (Capreolus capreolus), red deer (Cervus elaphus), and hare (Lepus europaeus). The designed primers were based on the noncoding, mitochondrial D-loop region. Amplicon sizes ranged from 116 to 255 bp. The primers exhibited no cross-reactivity with the DNA from common slaughter and other game species. The detection limit of the assay was established to be below 0.001 % in raw red deer (C. elaphus) and hare (L. europaeus) meat, and below 0.01 % in raw roe deer (C. capreolus) meat, whereas <0.5 % of hare and red deer meat in processed samples could be detected. The PCR-based assay was used for authentication of 17 samples of raw game meat and 32 samples of game meat-containing products available in Polish markets. Analysis of all tested raw meat and processed products revealed the presence of DNA of investigated species in concordance with producers’ declarations.  相似文献   
32.
The fruits of the mulberry tree (Morus alba L.), known as white mulberry, have been consumed in various forms, including tea, beverages, and desserts, worldwide. As part of an ongoing study to discover bioactive compounds from M. alba fruits, the anti-inflammatory effect of compounds from M. alba were evaluated in lipopolysaccharide (LPS)-stimulated mouse RAW 264.7 macrophages. Phytochemical analysis of the ethanol extract of the M. alba fruits led to the isolation of 22 compounds. Among the isolated compounds, to the best of our knowledge, compounds 1, 3, 5, 7, 11, 12, and 14–22 were identified from M. alba fruits for the first time in this study. Inhibitory effects of 22 compounds on the production of the nitric oxide (NO) known as a proinflammatory mediator in LPS-stimulated RAW 264.7 macrophages were evaluated using NO assays. Western blot analysis was performed to evaluate the anti-inflammatory effects of cyclo(L-Pro-L-Val) (5). We evaluated whether the anti-inflammatory effects of cyclo(L-Pro-L-Val) (5) following LPS stimulation in RAW 264.7 macrophages occurred because of phosphorylation of IκB kinase alpha (IKKα), IκB kinase beta (IKKβ), inhibitor of kappa B alpha (IκBα), nuclear factor kappa B (NF-κB) and activations of inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). Cyclo(L-Pro-L-Val) (5) significantly suppressed phosphorylations of IKKα, IKKβ, IκBα, and NF-κB and activations of iNOS and COX-2 in a concentration-dependent manner. Taken together, these results indicate that cyclo(L-Pro-L-Val) (5) can be considered a potential therapeutic agent for the treatment of inflammation-associated disorders.  相似文献   
33.
Structural and optical properties of InGaN/GaN triangular-shaped multiple quantum well (QW) structures were investigated under various conditions of growth parameters such as growth temperature, flow rate of Ga and/ or In composition, and well and barrier widths. The optical properties affected by the growth parameters were well correlated with an In band gap, which is determined by the potential depth and the In composition in the well region. The emission peak energy was almost independent of the barrier width due to the relaxation of the piezoelectric fields in the triangular-shaped QWs. Photoluminescence spectra of the InGaN/GaN multiple QW structures showed a parabolic curve centered at 2.66 eV. The optical property of the triangular-shaped multiple QWs was substantially improved due to formation of quantum dot-like In composition fluctuations.  相似文献   
34.
We have tried to stress that mutant oncogenes or overexpressed, nonmutated proto-oncogenes, in addition to their direct affect on promoting aberrant tumor cell proliferation (and survival), may possess a crucial indirect means of stimulating tumor cell growth through regulation of angiogenesis. This effect would never be observed in tissue culture studies of oncogene function using pure cultures of tumor cells, which probably helps explain why the pro-angiogenic function of oncogenes has not been appreciated until only relatively recently. Indeed, the very first indication of a possible contributory role of oncogenes, such as ras and myc, to tumor angiogenesis was first reported by Thompson et al. in 1989, who used reconstituted organ cultures of the mouse prostate gland for their studies (69). This potentially important contribution of oncogenes to tumor growth and development may prove to have an impact on how various signal transduction inhibitors that are now in early phase clinical trials, e.g., monoclonal neutralizing antibodies to the human EGF receptor (70), function in vivo as anti-tumor agents.  相似文献   
35.
A process for production of asymmetric porous structures of filtering elements by the method of vibration molding of a mixture of powders with different granulometric compositions is described. Theoretical and experimental curves of segregation modes versus vibration parameters are given. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 3, pp. 362–367, May–June, 1997.  相似文献   
36.
Powder injection moulding (PIM) is a rapidly growing technology for producing complex geometry, net shaped components from ceramics, metals, hard metals, and intermetallics. The shaping of ceramic powders using injection moulding has a highly creative aspect with regard to the complexity of the structural parts. This permits the most near-net shaping possible. Therefore, costly finishing of the sintered components can be reduced to a minimum or totally eliminated. This potential for ceramic injection moulding (CIM) has led in the recent past to intensified international research and development activities. A number of new binder systems have been developed, i.e., polyacetate based, PEG-polymer based, acrylic-polymer based, agarose-based, etc. The development in the area of new binder composition was in parallel assisted by a significant improvement in debinding processes. New debinding systems have been developed, i.e., computer assisted thermal debinding, extraction debinding, catalytic debinding, or even freeze drying or microwave assisted drying, which significantly shortened the debinding time from days to hours and lowered the emission of undesirable volatile organic by-products to a minimum. The formation of defects during the debinding process was also practically eliminated. Nitherlands Enegy Research Foundation ECN. Published in Poroshkovaya Metallurgiya, Nos. 3–4(406), pp. 16–23, March–April, 1999.  相似文献   
37.
There exists a need to quantify the radiological information contained in the digital measurements of the imaging technologies. These imaging technologies include computed tomography, nuclear medicine examinations, diagnostic ultrasound imaging, computer radiography and digitization of radiographic film images. A rapidly growing number of studies suggest that useful quantitation of radiographic information includes linear measurements for organ estimation, estimation of surface areas and volumes, estimation of tissue density, and the visualization of three-dimensional organ sites.  相似文献   
38.
Ternary Pt45Ru45Mn10/C, Pt45Ru45Mo10/C and Pt45Ru45W10/C catalysts were synthesized and physical and electrochemical properties were characterized. Particle sizes of the catalysts were determined by X-ray diffraction to be 3.9, 4.8 and 4.6 nm for the Mn, Mo and W incorporated catalysts, respectively. Electrochemically active surface areas were calculated from CO stripping results, which were 17.7, 17.2 and 15.7 m2/g catal for the Pt45Ru45Mn10/C, Pt45Ru45Mo10/C and Pt45Ru45W10/C catalysts, respectively. In methanol electro-oxidation, the Pt45Ru45W10/C catalyst showed highest mass and specific activities of 2.78 A/g cat. and 177 mA/m2, respectively, which were 22 and 100% higher than those of commercial PtRu/C. In the case of ethanol electro-oxidation, the Pt45Ru45Mo10/C catalyst exhibited highest mass and specific activities of 4.8 A/g catal and 280 mA/m2, respectively. Specific activity of the Pt45Ru45Mo10/C catalyst was 56% higher than that of the commercial PtRu/C.  相似文献   
39.
Rak  Jacek 《Wireless Networks》2015,21(2):673-684
Wireless Networks - Wireless mesh networks (WMNs) are considered as a promising alternative to wired local, or metropolitan area networks. However, owing to their exposure to various disruptive...  相似文献   
40.
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