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   187篇
  免费   31篇
  国内免费   2篇
电工技术   3篇
化学工业   63篇
金属工艺   1篇
机械仪表   4篇
建筑科学   5篇
能源动力   8篇
轻工业   43篇
水利工程   5篇
石油天然气   1篇
无线电   12篇
一般工业技术   37篇
冶金工业   5篇
自动化技术   33篇
  2024年   1篇
  2023年   3篇
  2022年   9篇
  2021年   30篇
  2020年   15篇
  2019年   25篇
  2018年   27篇
  2017年   16篇
  2016年   17篇
  2015年   11篇
  2014年   16篇
  2013年   22篇
  2012年   9篇
  2011年   12篇
  2010年   3篇
  2008年   2篇
  2005年   1篇
  2004年   1篇
排序方式: 共有220条查询结果,搜索用时 31 毫秒
41.
Although yoghurt butter oil as a fermented dairy product is widely consumed in several countries, its metabolic effects have not been fully elucidated. In this study, male Wistar rats were treated with standard diet, standard diet enriched with 10% or 20% (W/W) of either cow yoghurt butter oil (CYBO), sheep yoghurt butter oil (SYBO) or cottonseed oil (COT) for 20 weeks. Treatment of rats with CYBO or SYBO (at both concentrations) did not significantly influence haematological parameters, plasma lipids and liver histological structure. However, in contrast to popular belief, COT treatment at the higher dose induced leukocytosis, dyslipidaemia and liver steatosis.  相似文献   
42.

Stability and convergence analysis have been previously accomplished for some population-based search and swarm intelligence algorithms like Particle Swarm Optimization and Gravitational Search Algorithm. However, there is no adequate theoretical analysis for Bat Algorithm (BA) in the literature. The BA is a type of optimization algorithms which is inspired by the motion of small bats searching for hunting their preys. In this study, stability and convergence of the particle dynamics in the standard version BA are analyzed, and some restrictions are described. Then, new updating relations have been proposed. Also the dynamics of the algorithm have been investigated, and sufficient conditions for stability have been derived using Lyapunov stability analysis. Extensive simulation is used to examine the findings. The results confirm the theoretical predictions and indicate the stability and convergence of the proposed updating relations.

  相似文献   
43.
44.
In this study, magnetic nanoparticles (MNPs) coated with L-aspartic acid (F-Asp NPs) were synthesized through a co-precipitation method and conjugated with paclitaxel (PTX) (F-Asp-PTX NPs) by esterification reaction between the carboxylic acid end groups on MNPs surface and the hydroxyl groups of the PTX and studied its cytotoxic effect in vitro. The successful conjugating of PTX onto the nanoparticles (NPs) was confirmed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM) techniques. The results showed that the average size was 46.11?±?7.8 (mean?±?SD (n?=?25)) nm. The cytotoxicity of void of PTX and F-Asp-PTX NPs were compared to each other by MTT assay of the treated MCF-7 cell line. The F-Asp-PTX NPs showed pH-dependent drug release behavior. These studies specify that F-Asp-PTX NPs have a very remarkable anticancer effect, for breast cancer cell line.  相似文献   
45.
Local drug release in close vicinity of solid tumors is a promising therapeutic approach in cancer therapy. Implantable drug delivery systems can be designed to achieve controlled and sustained drug release. In this study, ultrathin porous membranes of silicon wafer were employed as compatible drug reservoir models. An anticancer model drug, curcumin (CUR), was successfully loaded into porous silicon containers (8.94?±?0.72% w/w), and then, cerium oxide nanocapping was performed on the open pores for drug protection and release rate prolongation. Next, layer-by-layer surface coating of the drug container with anionic (alginate) and cationic (chitosan) polymers rendered pH-responsivity to the device. The drug release profile was studied using reflectometric interference Fourier transform spectroscopy at different pH conditions. It was determined that faster decomposition of the polymeric layers and subsequent CUR release occur in acidic buffer (pH 5.5) compared to a neutral buffer. Various characterization studies, including dynamic light scattering, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy, contact angle measurement, ultraviolet–visible spectroscopy, and X-ray powder diffraction revealed that our system has the required physicochemical properties to serve as a novel pH-sensitive drug delivery implant for cancer therapy.  相似文献   
46.
We report, for the first time, binary ZnO/MnWO4 nanocomposites with p-n heterojunction fabricated by a simple ultrasonic-calcination route. The phase structure, morphology, and optical along with textural properties were comprehensively characterized. The photocatalytic performance was studied via degradations of rhodamine B, methyl blue and methyl orange (RhB, MB, MO), and fuchsine pollutants under visible-light illumination. The ZnO/MnWO4 nanocomposites exhibited better photocatalytic performance than their single components and the nanocomposite with 30?wt% MnWO4 showed the highest activity. Photocatalytic performance of this nanocomposite is 22.5, 17.7, 26.8, and 23.9 times higher than that of the ZnO sample in degradations of RhB, MB, MO, and fuchsine dyes, respectively. The improved photocatalytic performance was ascribed to the formation of p-n heterojunction between ZnO and MnWO4 with high charge separation efficiency as well as strong visible-light absorption ability. The possible mechanism for the improved photocatalytic performance was proposed. This study revealed that the novel ZnO/MnWO4p-n heterojunction can act as a promising visible-light-active photocatalyst for environmental applications.  相似文献   
47.
Hydrodynamic characteristics of a gas-solid semi-cylindrical fluidized bed was experimentally investigated and compared with that of a cylindrical bed by analysis of pressure fluctuations. Pressure fluctuations were analyzed in time and frequency domains using standard deviation, power spectral density function and discrete wavelet transform methods. Experiments were carried out in two semi-cylindrical and cylindrical fluidized beds of 14?cm in diameter each, operating in the bubbling fluidization regime at ambient pressure and temperature. Both beds were filled with glass beads of various sizes (120, 290 and 450?µm). The superficial gas velocity was varied in the range of 0.2–0.8?m/s. Results showed that although the minimum fluidization velocity is influenced by the particle size, it is not affected by the geometry of the bed. It was shown that the hydrodynamics of both beds are very similar and the difference is negligible. Number of large bubbles is slightly larger in the semi-cylindrical bed as compared with the cylindrical bed. Also, increase in the particle size and superficial gas velocity result in a greater difference between the number of large bubbles in both beds and the number of large bubbles in the semi-cylindrical bed increases slightly faster than in the cylindrical bed.  相似文献   
48.
Multimedia Tools and Applications - Extensive use of three dimensional models in various areas indicates the importance of 3D data retrieval accuracy. In this paper, a directional graph, is...  相似文献   
49.
Many applications such as location-based services and wireless sensor networks generate and deal with uncertain time series (UTS), where the “exact” value at each timestamp is unknown. Traditional correlation analysis and search techniques developed for standard time series are inadequate for UTS data analysis required in such applications. Motivated by this need, we propose suitable concepts and techniques for UTS correlation analysis. We formalize the notion of normalization and correlation for UTS in two general settings based on the available information at each timestamp: (1) PDF-based UTS (having probability density function) and (2) multiset-based UTS (having multiset of observed values). For each case, we formulate correlation as a random variable and develop techniques to determine the underlying probability density function. For setup (2), we also present probabilistic pruning and sampling techniques to speed up the search process. We conducted numerous experiments to evaluate the performance of the proposed techniques under different configurations using the UCR benchmark datasets. Our results indicate effectiveness of the proposed techniques. For setup (2), in particular, our results show significant improvement in space utilization and computation time. We believe the proposed ideas and solutions lend themselves to powerful tools for UTS analysis and search tasks.  相似文献   
50.
In this study, modification of poly(L-lactic acid) (PLLA) electrospun nanofibrous scaffolds blending with polyethylenimine (PEI) in different blend ratios was performed. The sample with 85:15 blend ratio revealed most promising results, and was selected for further modification with gelatin. It was found that the presence of PEI could enhanced porosity, mechanical properties, surface/bulk hydrophilicity and also gelatin grafting density about five times with positive effect on cell behavior. The results indicated that the limitations of PLLA electrospun nanofibers for potential application as a functional tissue engineering scaffold (i.e., poor cell adhesion and necrosis of host tissues as a result of providing acidic environment while degradation) could be overcome through blending with PEI and grafting with gelatin.  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