首页 | 官方网站   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   237篇
  免费   13篇
  国内免费   1篇
工业技术   251篇
  2023年   3篇
  2022年   10篇
  2021年   12篇
  2020年   6篇
  2019年   13篇
  2018年   12篇
  2017年   12篇
  2016年   19篇
  2015年   8篇
  2014年   9篇
  2013年   23篇
  2012年   19篇
  2011年   16篇
  2010年   10篇
  2009年   8篇
  2008年   5篇
  2007年   5篇
  2006年   6篇
  2005年   1篇
  2004年   2篇
  2003年   5篇
  2002年   4篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   7篇
  1997年   6篇
  1996年   4篇
  1994年   2篇
  1993年   4篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1987年   2篇
  1981年   1篇
  1980年   3篇
  1978年   2篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1961年   1篇
排序方式: 共有251条查询结果,搜索用时 15 毫秒
91.
In this study, the dispersion of multi‐walled carbon nanotubes (MWCNTs) in epoxy was facilitated by an anionic surfactant, linear alkyl benzene sulfonic acid. Different types of composites were prepared using a fixed amount of MWCNTs (0.5 wt%), in absence of solvent/surfactant, in presence of solvent and solvent/surfactant. The composites were characterized using Fourier transform infrared spectrophotometer, thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), universal testing machine, pendulum impact system, X‐ray diffraction, and scanning electron microscope. The epoxy/MWCNTs nanocomposite exhibited significantly higher mechanical properties due to the better dispersion in the presence of the surfactant. The tensile strength and flexural strength were increased by 75% and 108%, respectively. The thermal, structural, and morphological analyses were also excellent as a result of the better dispersion. In addition, the solvent‐surfactant behavior was hypothesized for the epoxy/MWCNTs system. POLYM. ENG. SCI., 59:E80–E87, 2019. © 2018 Society of Plastics Engineers  相似文献   
92.
The distribution of aflatoxin M1 (AFM1) has been investigated in samples of whey, curd and a typical hard and long maturing cheese like Grana Padano (ripened for twelve months), produced with naturally contaminated milk in a range of 30–98 ng AFM1/kg. AFM1 determinations were carried out on 25 samples of each product by reverse-phase HPLC and fluorescence detection with post-column derivatisation, after a preliminary C18-SPE clean-up. Experimental results show that, in comparison to milk, AFM1 concentration levels increased both in curd (3-fold) and in long maturing cheese (4.5-fold), while AFM1 occurrence in whey decreased by 40%.  相似文献   
93.
This research aims to enhance the interaction between a structure and its architectural form. Having a qualitative approach, the present work discovers some successfully used geometrical features of the Iranian ancient architecture in terms of the architectural-structural interaction. We define four qualitative criteria for this assessment, i.e., construction-ability, cost effectiveness, participation of the structure in fulfillment of the visual, and functional-semantic needs of the architectural form. For this purpose, two case studies including the Jamé Mosque of Isfahan and the Soltaniyeh building are investigated. The outcomes of this research help designers to not only design efficient structures by adapting non-load bearing elements with the general form of the structure, but also meet concepts such as the unity or perfectionism in the structure.  相似文献   
94.
Food authenticity and safety are major concerns for researchers, consumers, and particularly the meat industry. Meat products are targets for species substitution and adulteration due to their market value. Presently, the demand for halal products is witnessing a substantial increase. Therefore, it is essential to use appropriate science-based methods for determining the species origin of halal meat. DNA barcoding is a useful technique for the molecular identification of biological specimens, and raw and processed foods. The potential of using DNA barcoding is increasingly applied as an authentication tool for halal animal and meat products. Our review will bring together all DNA-based techniques that have been developed for the authenticity of meat derived from halal and non-halal animals and also their derivatives. Additionally, the present paper will highlight the possibility of using the DNA barcoding approach for halal meat authenticity.  相似文献   
95.
In this work, microwave-assisted digestion using the diluted nitric acid procedure for trace elements determination in rice samples by inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) was investigated in a multivariate way. The response surface methodology (RSM), based on the Box–Behnken design, was employed to obtain the optimum conditions of the significant parameters. The optimal conditions, for 250 mg of sample, could be obtained at a temperature of 200 °C, digestion time of 20 min, and 4.5 mol L?1 for nitric acid concentration. The accuracy of the optimized method was evaluated by analysis of the rice flour certified reference materials (NIST SRM 1568a) and spike recoveries. The results showed good agreement with the reference values of the CRM samples. The analytical method was applied to the determination of Al, As, Ca, Cd, Cu, Fe, K, Mg, Mn, Mo, Se, and Zn in rice samples. Considering some critical parameters such as cost, green chemistry, and analyst safety, the proposed method has advantages compared to classical microwave-assisted digestion procedures based on concentrated acids.  相似文献   
96.
In this work, we investigate the optical solitons to the non-linear Shrödinger’s equation with spatio-temporal dispersion. There are two types of non-linear media studied in this paper. They are Kerr law and parabolic law. By adopting a complex amplitude ansatz method composed of the addition of bright and dark optical solitons, we present the exact dark, bright and dark-bright or combined optical solitons to the model. Numerical results and discussions are also presented.  相似文献   
97.
Bioceramic scaffolds have a promising application in bone-tissue engineering field. However, bioceramic scaffolds exhibit low fracture toughness; hence, to overcome this problem, hierarchical bioceramic scaffold or bioceramic scaffolds coated with polymer are produced. Starting with the fundamental requirements for bioceramic scaffold, this article provides detailed information on recent developments of method to produce porous bioceramics scaffold and hierarchical bioceramic scaffold. Chemical modifications to enhance interfacial adhesion and formation of interpenetrating network structures between the bioceramic scaffold and the natural polymer layer are discussed in this article. Areas of future research are highlighted at the end of this review.  相似文献   
98.
This paper presents a new enhancement technique using the fuzzy set theory for low contrast and nonuniform illumination images. A new parameter called the contrast factor which will provide information on the difference among the gray-level values in the local neighborhood is proposed. The contrast factor is measured by both local and global information to ensure that the fine details of the degraded image are enhanced. This parameter is used to divide the degraded image into bright and dark regions. The enhancement process is applied on gray-scale images wherein the modified Gaussian membership function is employed. The process is performed separately according to the image’s respective regions. The performance of the proposed method is comparable with other state-of-the-art techniques in terms of processing time. The proposed method exhibits the best performance and defeats other methods in terms of preserving brightness and details without amplifying existing noises.  相似文献   
99.
100.
The dynamics of the microflora in the foci of surgical infection in 54 patients was studied. Staphylococci and streptococci prevailed among the primarily isolated causative agents. In complicated forms of surgical infection of soft tissues the change of causative agents, mainly to gram-negative opportunistic microflora with a higher level of resistance to antibiotics and high antilysozyme activity, was observed more often than in noncomplicated forms of such infection.  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-23

京公网安备 11010802026262号