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   91篇
  免费   5篇
  国内免费   9篇
电工技术   7篇
化学工业   18篇
金属工艺   2篇
机械仪表   3篇
建筑科学   6篇
能源动力   10篇
轻工业   18篇
水利工程   12篇
石油天然气   3篇
无线电   5篇
一般工业技术   15篇
冶金工业   3篇
原子能技术   1篇
自动化技术   2篇
  2024年   4篇
  2023年   2篇
  2022年   4篇
  2021年   9篇
  2020年   2篇
  2019年   3篇
  2018年   5篇
  2017年   8篇
  2016年   3篇
  2015年   3篇
  2014年   6篇
  2013年   6篇
  2012年   10篇
  2011年   6篇
  2010年   5篇
  2008年   4篇
  2007年   4篇
  2003年   6篇
  1998年   3篇
  1997年   3篇
  1996年   1篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1991年   1篇
排序方式: 共有105条查询结果,搜索用时 31 毫秒
1.
Elucidation of the biological functions of extracellular vesicles (EVs) and their potential roles in physiological and pathological processes is an expanding field of research. In this study, we characterized USC–derived EVs and studied their capacity to modulate the human immune response in vitro. We found that the USC–derived EVs are a heterogeneous population, ranging in size from that of micro–vesicles (150 nm–1 μm) down to that of exosomes (60–150 nm). Regarding their immunomodulatory functions, we found that upon isolation, the EVs (60–150 nm) induced B cell proliferation and IgM antibody secretion. Analysis of the EV contents unexpectedly revealed the presence of BAFF, APRIL, IL–6, and CD40L, all known to play a central role in B cell stimulation, differentiation, and humoral immunity. In regard to their effect on T cell functions, they resembled the function of mesenchymal stem cell (MSC)–derived EVs previously described, suppressing T cell response to activation. The finding that USC–derived EVs transport a potent bioactive cargo opens the door to a novel therapeutic avenue for boosting B cell responses in immunodeficiency or cancer.  相似文献   
2.
台阶地形上波浪运动的数值研究   总被引:4,自引:0,他引:4  
波浪在水深剧变地形上的传播,可以简化为波浪在台阶地形上的传播.利用二维数值波浪水槽可以很好地模拟这一过程,特别是对波浪在台阶上的非线性变形.数值计算结果与实验测量进行了比较,结果吻合良好.  相似文献   
3.
为解决云制造模式下企业服务能力有限性及客户需求不确定性问题,深入分析云制造企业群多时序生产服务模式,基于服务时间、成本和质量构建差异化产品生产优化模型,结合客户需求的偏好性与模糊性,引入三角模糊及广义诱导有序加权平均算子针对客户模糊需求给出区间型组合供应算法,确定协同制造企业群的最优组合.以包含4类差异制造需求的产品为例,进行MATLAB仿真实验,验证了所提模型与算法的有效性与可行性.结果表明,差异化产品增强了云制造服务流程的复杂性,多时序生产可较好地分解与重组制造任务,嵌入客户模糊化需求,从而提高云制造服务平台的运作效率及应用效果.  相似文献   
4.
这是曾被称为。就其数量、执着的程度,以及坚持艺术直接与普通大众对话这点而言,唯罗子丹最为突出”的实验艺术家罗子丹先生的文章。  相似文献   
5.
PMMA and PMMA films doped with different contents of azo dye have been made by using the casting technique. The absorption spectral analysis showed that the doped films have two absorption bands attributed to the π‐π* and n‐π* transition of chromophore groups. These bands disappear upon UV‐irradiation, suggesting that the studied system undergoes a photo degradation process. The absorption coefficient and optical energy gap (Eg) have been obtained from the absorption edge in the 200–900 nm range. It was found that Eg decreases with increasing doping levels, whereas it increases with increasing irradiation time. The width of the tail of localized states in the band gap (ΔE) was evaluated using the Urbach edge method. Some optical parameters were determined from the reflection and transmission spectra in the spectral range of 200–2500 nm. The dependence of the refractive index on irradiation time and doping level have been discussed. It was found that the photo‐induced refractive index changes are very large. These changes suggest the applicability of the studied system in optical devices. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   
6.
以粉红黏帚霉菌株总RNA为模板,采用RT-PCR技术克隆得到玉米赤霉烯酮降解酶基因cD-NA序列,插入pPIC9K载体后,转化毕赤酵母。经MD板筛选,得到His+型重组子,进行甲醇诱导表达,并进行了降解玉米赤霉烯酮能力测定。克隆得到的cDNA序列全长795 bp,连续编码编码264个氨基酸;阳性克隆子在甲醇诱导培养3~5 d后,HPLC检测证实,经表达后的酶液能完全降解液体中玉米赤霉烯酮(ZEN)。  相似文献   
7.
Wastes from agricultural industry are often disposed. Nevertheless, these wastes contain nutraceuticals and functional compounds. Xylooligosaccharide (XOS) was extracted from two sugarcane wastes (SW); rind (SR) and pith (SP), and the prebiotic properties of both XOS were examined. SR and SP had different mixture of XOS and were resistant towards α-amylase and gastric juice digestion in vitro. Although the growth of Lactobacillus casei Shirota (LcS) and Bifidobacterium animalis subsp. Lactis ATCC® 700541™ increased significantly in both XOS after 48 h of incubation, XOS from SR showed better enrichment of probiotics growth. Both XOS were found to be more fermentable by LcS and acetic acid was the predominant end product of the fermentation. Since XOS composition was different between SR and SP and such difference can affect their prebiotic properties, it is important to choose the appropriate parts of SW to extract XOS with high fermentable properties and obtain the best synbiotics combination.  相似文献   
8.
Poly(vinyl alcohol) (PVA) films filled with different amounts of CrF3 and MnCl2 were prepared by the casting method. Differential scanning calorimetry (DSC) and X‐ray diffraction (XRD) analysis were used to study the changes in the structure properties that occurred because of filling. The changes occurring in the measured parameters with increasing filler contents were interpreted in terms of the structural modification of the PVA matrix. All the studied samples had a main melting temperature due to the main crystalline phase of PVA. The intensity and position of this peak depended on the filling level. However, the samples of CrF3‐filled PVA films with a filling level greater than or equal to 10 wt % revealed another melting temperature, which indicated the presence of a new crystalline phase in addition to the main crystalline phase. The changes that occurred in the degree of crystallinity of the studied samples were examined. The calculated degree of crystallinity was formulated numerically to be an exponential function of the filling level. The XRD patterns of the studied samples confirmed the DSC results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1115–1120, 2003  相似文献   
9.
Mobile Health (mHealth) applications are readily accessible to the average user of mobile devices, and despite the potential of mHealth applications to improve the availability, affordability and effectiveness of delivering healthcare services, they handle sensitive medical data, and as such, have also the potential to carry substantial risks to the security and privacy of their users. Developers of applications are usually unknown, and users are unaware of how their data are being managed and used. This is combined with the emergence of new threats due to the deficiency in mobile applications development or the design ambiguities of the current mobile operating systems. A number of mobile operating systems are available in the market, but the Android platform has gained the topmost popularity. However, Android security model is short of completely ensuring the privacy and security of users’ data, including the data of mHealth applications. Despite the security mechanisms provided by Android such as permissions and sandboxing, mHealth applications are still plagued by serious privacy and security issues. These security issues need to be addressed in order to improve the acceptance of mHealth applications among users and the efficacy of mHealth applications in the healthcare systems. Thus, this paper presents a conceptual framework to improve the security of medical data associated with Android mHealth applications, as well as to protect the privacy of their users. Based on the literature review that suggested the need for the intended security framework, three-distinct and successive phases are presented, each of which is described in a separate section. First, discussed the design process of the first phase to develop a security framework for mHealth apps to ensure the security and privacy of sensitive medical data. The second phase is discussed who to achieve the implementation of a prototypic proof-of-concept version of the framework. Finally, the third phase ending discussed the evaluation process in terms of effectiveness and efficiency for the proposed framework.  相似文献   
10.
肌内结缔组织是肌肉的重要组成部分,与肌纤维共同影响肉品的感官品质。该文对结缔组织与肉品嫩度、多汁性、风味等感官品质指标的关系进行总结,并聚焦于结缔组织主要成分胶原蛋白,总结其在加热过程中变性、收缩和溶解等热特性的影响因素,分析其热特性和结缔组织蛋白聚糖降解的关系,以及其热特性与原料肉内源酶降解体系的关系,探讨结缔组织影响肉品品质的可能机制,以期为改变结缔组织的热特性,提高肉品的感官品质指明研究方向。  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