全文获取类型
收费全文 | 448篇 |
免费 | 23篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
综合类 | 2篇 |
化学工业 | 101篇 |
金属工艺 | 9篇 |
机械仪表 | 10篇 |
建筑科学 | 6篇 |
矿业工程 | 2篇 |
能源动力 | 23篇 |
轻工业 | 56篇 |
水利工程 | 5篇 |
石油天然气 | 9篇 |
无线电 | 50篇 |
一般工业技术 | 93篇 |
冶金工业 | 25篇 |
原子能技术 | 10篇 |
自动化技术 | 64篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 26篇 |
2021年 | 25篇 |
2020年 | 26篇 |
2019年 | 23篇 |
2018年 | 25篇 |
2017年 | 21篇 |
2016年 | 28篇 |
2015年 | 20篇 |
2014年 | 23篇 |
2013年 | 39篇 |
2012年 | 22篇 |
2011年 | 21篇 |
2010年 | 9篇 |
2009年 | 16篇 |
2008年 | 19篇 |
2007年 | 21篇 |
2006年 | 8篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有472条查询结果,搜索用时 31 毫秒
451.
Ran Yan Abhinav Kranti Isabelle Ferain Chi-Woo Lee Ran Yu Nima Dehdashti Pedram Razavi Jean-Pierre Colinge 《Microelectronics Reliability》2011,51(7):1166-1171
The performances of the junctionless nanowire transistor (JNT) are evaluated under high-performance (HP) ITRS device technical requirements for the 25 nm technology node. The electrical characteristics of the devices are obtained from numerical simulations. The threshold voltage of JNT can be easily adjusted by changing different variable parameters such as fin width, fin thickness, doping concentration, gate oxide thickness and gate work function. The variation of threshold voltage with physical parameters is analyzed. The current drive is controlled by doping concentration and nanowire size. For gate length down to 25 nm, a 30-40% increase in drain current is also reported by using a fin aspect ratio of 2 instead of 1. Additional source and drain implantation can be applied to improve the current drive. 相似文献
452.
This paper presents an RF front-end architecture for wideband software defined radio to function in 400 MHz to 3.5 GHz frequency
range. The frequency range covers almost all the existing standards (like GSM, UMYS, CDMA, WiFi etc.) as well as future standards
(like WiMax which is still to be deployed). Although the 400 MHz–3.5 GHz band is taken, the architecture allows designers
to design the front-end for any range of frequencies. In wideband front-ends, devices with high linearity are used to lower
the level of intermodulation products. There are different front-end architectures available for catering to wideband operation.
However, some of these, particularly the wideband ones suffer with intermodulation problem. This paper presents a partitioning
mechanism that uses multiple medium bands to limit the intermodulation problem. The proposed frequency-partitioning scheme
makes it possible to suppress intermodulation products further for front-end using devices of given linearity. Thus this helps
in achieving better performance along with relaxing the linearity requirement of devices. 相似文献
453.
Dinesh Upadhyay Smita Mohanty Sanjay K. Nayak M. Rahail Parvaiz Bishnu P. Panda 《应用聚合物科学杂志》2011,120(2):932-943
A poly(trimethylene terephthalate) (PTT)/polypropylene (PP) blend and the nanocomposites were prepared with and without the addition of a compatibilizer precursor [maleic anhydride grafted polypropylene (MAPP)]. A reactive route was used for the compatibilization with the addition of MAPP during melt blending in a batch mixer. Organically modified nanoclays were used as nanoscale reinforcements to prepare the blend nanocomposites. Mechanical tests revealed optimum performance characteristics at a PTT/PP blend ratio of 80 : 20. Furthermore, incorporation of nanoclays up to 3 wt % showed a higher impact strength and higher tensile strength and modulus in the blend nanocomposites compared to the optimized blend. The nanocomposite formation was established through X‐ray diffraction and transmission electron microscopy (TEM). Thermal measurements were carried out with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC thermograms revealed an increase in the crystallization temperature in the presence of the nanoclays in the blend system containing Cloisite 30B. TGA thermograms also indicated that the thermal stability of blend increased with the incorporation of Cloisite 30B. Furthermore, dynamic mechanical analysis measurements showed that the Cloisite 30B nanocomposite had the maximum modulus compared to other nanocomposites. TEM micrographs confirmed an intercalated morphology in the blend nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
454.
Methanol extract and sub-fractions of Smilax sebeana rhizomes and roots were analyzed to evaluate the compounds involved in antioxidant activity. In all separated fractions of the different polarity solvents, ethyl acetate fraction showed the highest antioxidant activity and total phenolic content. This fraction was subjected to the sephadex LH-20 column and preparative HPLC for purification. Six phenolic compounds, chlorogenic acid (1), 4-formylphenol (2), epicatechin (3), cinchonain IIa (4), Ia (5) and Ib (6) were isolated and identified by spectroscopic analyses and further evaluated their potential antioxidant activities by DPPH and superoxide radical scavenging assays. Compared with synthetic antioxidant Trolox, except 4-formylphenol, the other isolated five compounds exhibited excellent antioxidant activities. This is the first report on the chemical constituents of S. sebeana which potentially involved in antioxidant activity. The results suggest that the ethyl acetate extract of S. sebeana might be used as a readily accessible source of natural antioxidant. 相似文献
455.
Pineapple stem has been extensively used for bromelain extraction; however, almost no attention has been given to the waste obtained during bromelain manufacturing. In this regard, antioxidant, antimicrobial, and inhibitions against 15-lipoxygenase and advanced glycation end product formations by pineapple stem waste (PSW) obtained during bromelain manufacturing process were studied. The PSW had moderate bioactivities in all the performed assays. It also showed a considerable inhibition against fungal growth, probably due to high amounts of the benzoic acid present in the sample. These results indicate that PSW could be utilized as an economic source of preventive or therapeutic agent in disease and in different functional food industries. PRACTICAL APPLICATION: A large amount of wastes are generated during bromelain manufacturing from pineapple stem. So far, these wastes are not utilized and are often considered as a burden while disposing them. However, we found some important phytochemicals with considerable bioactivities in these wastes. We believe that these wastes may have a promising usage as a cheap source of one of the ingredients in functional food based industries. 相似文献
456.
Kumar Abhinav Dubey Yatender K. Bhardwaj Chandrashekhar V. Chaudhari Sunil Sabharwal 《Polymer Composites》2011,32(5):737-746
Nanocomposites of low‐density polyethylene (LDPE)/ethyl vinyl acetate (EVA)/poly(chloroprene) rubber (PCR) blends and multiple walled carbon nanotubes (MWNT) were prepared in different compositions by melt mixing. The nanocomposites were subjected to different radiation doses and efficacy of radiation crosslinking and physic‐mechanical characteristics were analyzed in detail. Gel content and crosslinking density increased with dose and with the MWNT fraction in the nanocomposites. The elastic modulus of the nanocomposite increased, while elongation at break exhibited downward trend with radiation dose. Micromechanical modeling of elastic modulus indicated presence of agglomeration in the matrix. Bulk density of the nanocomposites increased with the addition of MWNT while the melt flow index of the nanocomposites decreased sharply. DSC, XRD and TGA investigations revealed the peculiarity of the MWNT led nucleation in LDPE/EVA/PCR/MWNT nanocomposites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers 相似文献
457.
458.
Iodine deficiency disorders (IDD) is still a major public health problem and iodized salt remains the most effective means to control IDD in India. Few reports indicate that vegans have inadequate iodine intake while at the same time concerns are being raised on the implementation of universal salt iodization in the country. Therefore, we investigated the iodine content in bread, milk and commonly used Indian recipes prepared without iodized salt and the retention of inherent iodine therein. Results showed considerable iodine content in bread (25 μg/100 g) and milk (303 μg/L) as a positive fallout of universal salt iodization. Iodine content in 38 vegetarian recipes prepared without iodized salt was very low (2.9 ± 2.4 μg/100 g). Retention of inherent iodine (65.6 ± 15.4%) and iodine from iodized salt (76.7 ± 10.3%) in the same recipes was comparable. Thus, universal salt iodization programme remains the single most important source of dietary iodine for the Indian population. 相似文献
459.
Upadhyay Shipra Pandey Amit Kumar Pandey Shailendra Kumar Gupta Tarun Kumar Pandey Digvijay 《SILICON》2022,14(15):9367-9378
Silicon - In this article, a novel silicon adiabatic circuit is proposed for low power applications. To achieve efficient performance, the charging and the discharging diodes in the energy recovery... 相似文献
460.
Silicon - The channel modulated junctionless gate all around (CM-JL-GAA) MOSFET improves the SCE’s with high graded doping of the channel region. Temperature effects on electrostatic and... 相似文献