全文获取类型
收费全文 | 230篇 |
免费 | 17篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 42篇 |
金属工艺 | 3篇 |
机械仪表 | 10篇 |
建筑科学 | 5篇 |
矿业工程 | 1篇 |
能源动力 | 12篇 |
轻工业 | 41篇 |
水利工程 | 1篇 |
石油天然气 | 6篇 |
无线电 | 31篇 |
一般工业技术 | 57篇 |
冶金工业 | 4篇 |
原子能技术 | 3篇 |
自动化技术 | 25篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 16篇 |
2020年 | 16篇 |
2019年 | 20篇 |
2018年 | 15篇 |
2017年 | 16篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 21篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 7篇 |
2009年 | 10篇 |
2008年 | 5篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 6篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1980年 | 1篇 |
1975年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有247条查询结果,搜索用时 31 毫秒
21.
J. F. Branthaver Muhammed Nazir J. C. Petersen S. M. Dorrence Michael J. Ryan 《Petroleum Science and Technology》1984,2(1):67-89
Four selected asphalts were blended with zero to five wt. percent of fractions rich in vamady cheltes prepared from two crude oils. The mixture was -coated in a teflon -support, and the whole was heated in an oven at. 113±2°C for 24 hours. The mixture then was analyzed for increases ketone, acid and anhydride functions.
in general, functions rich in vanady ponphyrims tended to promote asphalt oxidation, particularly as measured by increase in kentones. Corelation of vanadyl ponphyrim concentration with asphalt oxidation is observed to the direct only if asphalts are mixed with varying amounts of the same fraction derived from the same crude Possible reasons for this phenomenon are discussed in terms of oxidation susceptibility of aspha1ts, the importance of molecular associations, and the relative catalytic activities of metallaporphyrins and other metal chelates 相似文献
in general, functions rich in vanady ponphyrims tended to promote asphalt oxidation, particularly as measured by increase in kentones. Corelation of vanadyl ponphyrim concentration with asphalt oxidation is observed to the direct only if asphalts are mixed with varying amounts of the same fraction derived from the same crude Possible reasons for this phenomenon are discussed in terms of oxidation susceptibility of aspha1ts, the importance of molecular associations, and the relative catalytic activities of metallaporphyrins and other metal chelates 相似文献
22.
Advances in processing of superconductors has demonstrated that ceramic powders with exact composition, super-homogeneity,
and extremely fine particle size can be prepared by chemical processing to achieve high density and uniform microstructure.
The chemical processing routes have great advantage in preparing powder with high reactivity thus promoting solid state reactions
required to produce ‘purer’ superconducting phase. We have studied extensively the coprecipitation technique for the preparation
of superconducting ceramic powders. Chemical solution methods have been used in order to model several superconducting systems
and to predict optimum conditions for obtaining exact composition. Several improvements on the control of precipitation reaction
have been implemented in order to obtain powders of few nanometers in size. This has been done by carrying out the reaction
in the bulk of a solution or in microemlusion systems. The corecipitated precursor powder has been used for production of
20− 30 meter long Ag-clad tapes. These tapes require considerably reduced processing times. By controlled heat treatment conditions,
these tapes have been processed to carry transport critical current density, Jc <4 × 104 A/cm2 at 77K in zero applied field. 相似文献
23.
Mehmet Sagbas Umut E. Ayten Herman Sedef Muhammed Koksal 《AEUE-International Journal of Electronics and Communications》2009,63(5):423-427
In this letter, a new floating inductance simulator circuit is presented. The proposed structure consists of only one grounded capacitor without any external resistors and two different active elements. The active elements are dual-output current-controlled current conveyor (DO-CCCII) and operational transconductance amplifier (OTA). The proposed inductance simulator can be tuned electronically by changing the biasing current of the DO-CCCIIs or by changing the current of the OTA. Moreover, the circuit does not require any conditions of component matching. It has a good sensitivity performance with respect to tracking errors. As an application, the proposed inductance simulator is used to construct a fourth-order resistively terminated LC band-pass filter. The theoretical analysis is verified by the SPICE simulation results. 相似文献
24.
Muhammed A. Ibrahim Shahram Minaei Erkan Yuce 《International Journal of Circuit Theory and Applications》2012,40(5):477-488
In this paper, two new circuit configurations for realizing voltage‐mode (VM) all‐pass sections (APSs) are presented. The proposed circuits employ only two differential voltage current conveyors (DVCCs) and are cascadable with other VM circuits due to their high‐input and low‐output impedances. The first configuration uses a grounded resistor and a grounded capacitor without requiring matching constraints, whereas the second employs two grounded resistors and a grounded capacitor with a single matching condition. While the first configuration can realize only one all‐pass response, the second can provide inverting and non‐inverting all‐pass responses with selection of appropriate input port. Adding two grounded resistors to the proposed filters, variable gain APSs can also be obtained. As applications, two quadrature oscillators, each of which using one of the proposed all‐pass circuits, one grounded resistor and one grounded capacitor are presented. SPICE simulation results are included to verify the theory. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
25.
Muhammed Muhsin Varikkodan Chun-Chung Chen Tzong-Yuan Wu 《International journal of molecular sciences》2021,22(15)
Chikungunya virus (CHIKV) is a mosquito-transmitted infectious agent that causes an endemic or epidemic outbreak(s) of Chikungunya fever that is reported in almost all countries. This virus is an intense global threat, due to its high rate of contagion and the lack of effective remedies. In this study, we developed two baculovirus expression vector system (BEVS)-based approaches for the screening of anti-CHIKV drugs in Spodoptera frugiperda insect (Sf21) cells and U-2OS cells. First, structural protein of CHIKV was co-expressed through BEVS and thereby induced cell fusion in Sf21 cells. We used an internal ribosome entry site (IRES) to co-express the green fluorescent protein (EGFP) for identifying these fusion events. The EGFP-positive Sf21 cells fused with each other and with uninfected cells to form syncytia. We identified that ursolic acid has potential anti-CHIKV activity in vitro, by using this approach. Second, BacMam virus-based gene delivery has been successfully applied for the transient expression of non-structural proteins with a subgenomic promoter-EGFP (SP-EGFP) cassette in U-2OS cells to act as an in vitro CHIKV replicon system. Our BacMam-based screening system has identified that the potential effects of baicalin and baicalein phytocompounds can inhibit the replicon activity of CHIKV in U-2OS cells. In conclusion, our results suggested that BEVS can be a potential tool for screening drugs against CHIKV. 相似文献
26.
27.
The objective of this research was to investigate and compare the effect of different treatments including gaseous ozone (6-ppm/4-min), ultrasound (450 W/4 min) and coating of shellac, lysozyme–chitosan (L-C) on fresh eggs internal quality during storage for six weeks at ambient temperature. The internal quality attributes such as weight loss (WL), albumen viscosity, Haugh unit (HU), yolk index, total soluble solids, albumen and yolk's pH were monitored. Control groups had the worst HU (50.04), WL (8.35%), albumen pH (9.27) and viscosity (7.72 mPa·s) values after storage. The best interior qualities were obtained by shellac coating [HU (72.37), WL (1.37) and viscosity (30.10 mPa·s)] and sonication (albumen pH: 8.22). Thus, the shellac-coated eggs maintained all the internal quality parameters at the highest values, while the ozone and ultrasound only helped to keep the internal quality and enhance the shelf life of eggs. 相似文献
28.
Guzel Muhammed Huseyin Unal Recep Emre Onder Ahmet Sen Muhammed Arif Kose Faruk 《Journal of Mechanical Science and Technology》2021,35(3):1301-1308
Journal of Mechanical Science and Technology - The energy demand of world is increasing worldwide because of increasing population and developing technology. The use of environmentally friendly... 相似文献
29.
Cherakkathodi Sudheesh Kappat Valiyapeediyekkal Sunooj K.U. Anjali Basheer Aaliya Muhammed Navaf Sunny Kumar Vallayil Appukuttan Sajeevkumar Johnsy George 《International Journal of Food Science & Technology》2020,55(6):2391-2398
Physico-chemical, retrogradation, rheological properties and in vitro digestibility of lysine incorporated kithul starch modified by annealing, heat moisture treatment and its combinations were studied. LS-AHMT (annealed-heat moisture treated lysine incorporated kithul starch) exhibited lowest amylose leaching. LS-AHMT showed significantly (P ≤ 0.05) higher relative crystallinity. LS-ANS (annealed lysine incorporated kithul starch), LS-HMT (heat moisture treated lysine incorporated kithul starch) and LS-AHMT formed more weak gel by the effect of annealing, heat moisture treatment and its combination. LS-AHMT showed lowest pasting viscosities, G′ and G″ values among the modified kithul starch, which indicates its lower retrogradation properties. In vitro digestibility of kithul starch decreased after modifications and LS-ANS, LS-HMT and LS-AHMT showed significantly higher resistant starch content. The current study showed that annealing, heat moisture treatment and its combination on NS-LS (lysine incorporated kithul starch) effectively modified kithul starch properties. 相似文献
30.
Masoud Muhammed Hassan Haval Ismael Hussein Adel Sabry Eesa Ramadhan J. Mstafa 《计算机、材料和连续体(英文)》2021,68(2):1637-1659
Over the past few decades, face recognition has become the most effective biometric technique in recognizing people’s identity, as it is widely used in many areas of our daily lives. However, it is a challenging technique since facial images vary in rotations, expressions, and illuminations. To minimize the impact of these challenges, exploiting information from various feature extraction methods is recommended since one of the most critical tasks in face recognition system is the extraction of facial features. Therefore, this paper presents a new approach to face recognition based on the fusion of Gabor-based feature extraction, Fast Independent Component Analysis (FastICA), and Linear Discriminant Analysis (LDA). In the presented method, first, face images are transformed to grayscale and resized to have a uniform size. After that, facial features are extracted from the aligned face image using Gabor, FastICA, and LDA methods. Finally, the nearest distance classifier is utilized to recognize the identity of the individuals. Here, the performance of six distance classifiers, namely Euclidean, Cosine, Bray-Curtis, Mahalanobis, Correlation, and Manhattan, are investigated. Experimental results revealed that the presented method attains a higher rank-one recognition rate compared to the recent approaches in the literature on four benchmarked face datasets: ORL, GT, FEI, and Yale. Moreover, it showed that the proposed method not only helps in better extracting the features but also in improving the overall efficiency of the facial recognition system. 相似文献