全文获取类型
收费全文 | 711篇 |
免费 | 21篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 5篇 |
综合类 | 1篇 |
化学工业 | 102篇 |
金属工艺 | 22篇 |
机械仪表 | 14篇 |
建筑科学 | 4篇 |
矿业工程 | 1篇 |
能源动力 | 31篇 |
轻工业 | 38篇 |
石油天然气 | 1篇 |
无线电 | 98篇 |
一般工业技术 | 199篇 |
冶金工业 | 99篇 |
原子能技术 | 3篇 |
自动化技术 | 121篇 |
出版年
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 16篇 |
2017年 | 14篇 |
2016年 | 17篇 |
2015年 | 10篇 |
2014年 | 25篇 |
2013年 | 44篇 |
2012年 | 32篇 |
2011年 | 48篇 |
2010年 | 32篇 |
2009年 | 22篇 |
2008年 | 36篇 |
2007年 | 32篇 |
2006年 | 16篇 |
2005年 | 20篇 |
2004年 | 10篇 |
2003年 | 31篇 |
2002年 | 22篇 |
2001年 | 19篇 |
2000年 | 13篇 |
1999年 | 17篇 |
1998年 | 30篇 |
1997年 | 20篇 |
1996年 | 19篇 |
1995年 | 17篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有739条查询结果,搜索用时 10 毫秒
1.
Ferrite particles coated with biocompatible phases can be used for hyperthermia treatment of cancer. We have synthesized substituted
calcium hexaferrite, which is not stable on its own but is stabilized with small substitution of La. Hexaferrite of chemical
composition (CaO)0.75(La203)0.20(Fe2O3)6 was prepared using citrate gel method. Hydroxyapatite was prepared by precipitating it from aqueous solution of Ca(NO3)2 and (NH4)2HPO4 maintaining pH above 11. Four different methods were used for coating of hydroxyapatite on ferrite particles. SEM with EDX
and X-ray diffraction analysis shows clear evidence of coating of hydroxyapatite on ferrite particles. These coated ferrite
particles exhibited coercive field up to 2 kOe, which could be made useful for hysteresis heating in hyperthermia. Studies
by culturing BHK-21 cells and WBC over the samples show evidence of biocompatibility. SEM micrographs and cell counts give
clear indication of cell growth on the surface of the sample. Finally coated ferrite particle was implanted in Kasaulli mouse
to test its biocompatibility. The magnetic properties and biocompatibility studies show that these hydroxyapatite coated ferrites
could be useful for hyperthermia. 相似文献
2.
3.
Michael Osterman Abhijit Dasgupta 《Journal of Materials Science: Materials in Electronics》2007,18(1-3):229-236
The transition from lead (Pb) bearing solder to Pb-free solder has arisen in response to government restrictions on the use
of lead (Pb) by the European Union. As a result, electronic manufacturers have sought a material comparable to the conventional
63Sn37Pb solder that has been traditionally used to assemble electronic hardware. Based on extensive review of various solder
combination, the majority of electronic manufacturers appear to be adopting a tin–silver–copper (SAC) solder as a popular
Pb-free solder replacement. Significant investments have been made by many researchers to characterize the material behavior
and durability of this solder system. While the exact composition of the SAC solder is still in question, it now appears that
the 96.5Sn3.0Ag0.5Cu (SAC305) solder is gaining wider acceptance as the favored Pb-free replacement, for surface mount assemblies
that are going to be subjected predominantly to cyclic thermal environments. This paper presents a review of our current understanding
of the life expectancy of Pb-free SAC solder interconnects for electronic hardware. To this end, the paper focuses on material
characterization of SAC solder, as well as its temperature cycling and vibration fatigue reliability. From this review, SAC
solder interconnects are shown to be suitable for providing adequate life expectancies for temperature cycling in electronic
hardware. However, it is clear that there are differences between SAC and the conventional Sn37Pb solder, that need to be
understood in order to design reliable electronic hardware. 相似文献
4.
5.
Dasgupta U. Wooi Gan Yeoh Chun Geik Tan Sheng Jau Wong Mori H. Singh R. Itoh M. 《Microwave Theory and Techniques》2002,50(11):2443-2452
An implementation of the IF section of WCDMA mobile transceivers with a set of two chips fabricated in an inexpensive 0.35-/spl mu/m two-poly three-metal CMOS process is presented. The transmit/receive chip set integrates quadrature modulators and demodulators, wide dynamic range automatic gain control (AGC) amplifiers, with linear-in-decibel gain control, and associated circuitry. This paper describes the problems encountered and the solutions envisaged to meet stringent specifications, with process and temperature variations, thus overcoming the limitations of CMOS devices, while operating at frequencies in the range of 100 MHz-1 GHz. Detailed measurement results corroborating successful application of the new techniques are reported. A receive AGC dynamic range of 73 dB with linearity error of less than /spl plusmn/2 dB and spread of less than 5 dB for a temperature range of -30/spl deg/C to +85/spl deg/C in the gain control characteristic has been measured. The modulator measurement shows a carrier suppression of 35 dB and sideband/third harmonic suppression of over 46 dB. The core die area of each chip is 1.5 mm/sup 2/. 相似文献
6.
Two techniques for designing function-dependent easily testable programmable logic arrays are presented. The techniques can detect all the multiple stuck-at, crosspoint and bridging faults, as compared with most of the existing techniques where some of the faults, especially bridging faults, remain undetected.<> 相似文献
7.
8.
Sheetal Rani Basundhara Dasgupta Gaurav Kumar Bhati Kalpana Tomar Dr. Sabyasachi Rakshit Dr. Subhabrata Maiti 《Chembiochem : a European journal of chemical biology》2021,22(7):1113-1113
Evolutionarily elderly proteins commonly feature greater catalytic promiscuity. Cytochrome c is among the first set of proteins in evolution to have known prospects in electron transport and peroxidative properties. Here, we report that cyt c is also a proficient proton-transfer catalyst and enhances the Kemp elimination (KE; model reaction to show proton transfer catalytic property) by ∼750-fold on self-organized systems like micelles and vesicles. The self-organized systems mimic the mitochondrial environment in vitro for cyt c. Using an array of biophysical and biochemical mutational assays, both acid–base and redox mechanistic pathways have been explored. The histidine moiety close to hemin group (His18) is mainly responsible for proton abstraction to promote the concerted E2 pathway for KE catalysis when cyt c is in its oxidized form; this has also been confirmed by a H18A mutant of cyt c. However, the redox pathway is predominant under reducing conditions in the presence of dithiothreitol over the pH range 6–7.4. Interestingly, we found almost 750-fold enhanced KE catalysis by cyt c compared to aqueous buffer. Overall, in addition to providing mechanistic insights, the data reveal an unprecedented catalytic property of cyt c that could be of high importance in an evolutionary perspective considering its role in delineating the phylogenic tree and also towards generating programmable designer biocatalysts. 相似文献
9.
R. Maji S. Bhattacharyya S. Dasgupta S. Bandyopadhyay R. Mukhopadhyay A. S. Deuri 《应用聚合物科学杂志》2007,104(4):2735-2742
The basic objective of this article is to improve the polymer blend properties by changing mixing sequence. Blending of two elastomers does not lead to a molecularly homogeneous blend (true solution), but to a heterogeneous system in which both polymer phases are present. In this article, the detailed study of heterogeneous distribution of carbon black as well as blend inhomogenity and the physicomechanical including dynamic mechanical properties of the blend has been carried out. The choice of the blend was natural rubber/polybutadiene rubber as 85:15. Heterogeneous carbon black distribution study was also performed in differential scanning calorimeter. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2735–2742, 2007 相似文献
10.
Sorption of sulfur dioxide (SO2) was carried out on calcium‐based sorbents under dynamic conditions in a fixed bed. The experimental conditions were reaction temperature (700 to 1000°C), SO2 concentration (1000‐10 000 ppm), sorbent particles size (1 to 2 mm) and the types of sorbents (hydroxide or carbonate). The sorption process was found to be effective at low concentration levels (less than 10 000 ppm) as the breakthrough time significantly decreased with increase in concentration. The maximum removal of SO2 was observed at a reaction temperature of 950°C. The hydroxide‐based sorbents of relatively smaller particle size were found to exhibit superior sorption performance in terms of longer breakthrough time and higher sulfate conversion. A mathematical model developed, assuming a porous structure of the sorbent materials, attributed the low sulfation conversion during SO2 sorption due to a pore diffusion mechanism. 相似文献