全文获取类型
收费全文 | 366篇 |
免费 | 17篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 13篇 |
化学工业 | 95篇 |
金属工艺 | 6篇 |
机械仪表 | 6篇 |
建筑科学 | 5篇 |
矿业工程 | 3篇 |
能源动力 | 14篇 |
轻工业 | 22篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 84篇 |
一般工业技术 | 64篇 |
冶金工业 | 26篇 |
原子能技术 | 1篇 |
自动化技术 | 43篇 |
出版年
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 19篇 |
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 20篇 |
2017年 | 16篇 |
2016年 | 9篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 26篇 |
2008年 | 11篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 10篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有385条查询结果,搜索用时 171 毫秒
51.
Wireless Personal Communications - gold-MUSIC based direction of arrival (DOA) estimation and multiuser detection (MUD) overcoming near–far problem are achieved concurrently for... 相似文献
52.
Success of a scientific entity generally undergoes myriad vicissitudes, resulting in different patterns of success trajectories. Understanding and characterizing the rise and fall of scientific success is important not only from the perspective of designing new mathematical models but also to enhance the quality of various real-world systems such as scientific article search and recommendation systems. In this paper, we present a large-scale study of the subject by analyzing the success of two major scientific entities—papers and authors—in Computer Science and Physics. We quantify “success” in terms of citations and in the process discover six distinct success trajectories which are prevalent across multidisciplinary datasets. Our results reveal that these trajectories are not fully random, but are rather generated through a complex process. We further shed light on the behavior of these trajectories and unfold many interesting facets by asking fundamental questions—which trajectory is more successful, how significant and stable are these categories, what factors trigger the rise and fall of trajectories? A few of our findings sharply contradict the well-accepted beliefs on bibliographic research such as “Preferential Attachment”, “first-mover advantage”. We believe that this study will argue in favor of revising the existing metrics used for quantifying scientific success. 相似文献
53.
Precise measurements on the electrical conductivity of solutions of sodium polystyrenesulphonate in methanol–water mixed solvent media containing 8, 16, 25, and 34 wt.% of methanol at 308.15, 313.15, 318.15, and 323.15 K are reported. The degree of substitution of sodium polystyrenesulphonate used was 1, and the concentrations were varied from ∼2.0 × 10−4 to ∼4.0 × 10−3 monomol l−1. The results showed a slight and monotonous increase in the equivalent conductivity with decreasing polyelectrolyte concentration. The applicability of the Manning’s theory for salt-free polyelectrolyte solution was examined and a major discrepancy against the theory was observed. The calculated values of the equivalent conductivity deduced on the basis of this theory were found to be lower than the experimental ones. Possible reasons for this discrepancy have been discussed. The effects of the temperature and relative permittivity of the medium on the equivalent conductivity were also investigated. Estimation of the fractions of uncondensed counterions provides important insight regarding the solution behavior of the polyelectrolyte in methanol–water mixtures. 相似文献
54.
Chethana Rao Syamantak Khan Navneet C. Verma Dr. Chayan Kanti Nandi 《Chembiochem : a European journal of chemical biology》2017,18(24):2385-2389
We present efficient labelling of several proteins with orange‐emissive carbon dots. N‐Hydroxysuccinimide was used to activate the carboxyl groups of carbon dots, which subsequently reacted with the lysine groups present on the protein. Labelling was confirmed by UV absorption spectroscopy, PAGE and fluorescence correlation spectroscopy. Protein‐conjugated carbon dots showed an enhancement in fluorescence lifetime and intensity owing to reduced intramolecular dynamic fluctuations. Single‐molecule fluorescence measurements showed reduced fluorescence fluctuations and higher photon budget after protein tagging. Our study opens up opportunities to use carbon dots as highly precise biolabelling probes. 相似文献
55.
Santosh Kumar Vinod Kumar R. K. Nandi T. S. Suresh Ramen Datta 《Journal of Failure Analysis and Prevention》2008,8(6):492-497
Silicomanganese grade billets are the most commonly used steels for manufacture of automobile leaf springs. However, Cr-Mn-B
grade steel known by trade name of SUP 11A grade is replacing the conventional silicomanganese grades such as 60Si7 or 65Si7
steels because it has become a competitive alternative in the market. Three heats of SUP11A grade spring steel were made through
BOF-VAD-CC route and continuously cast into 125 × 125 mm billets. Some of the billets contained blowholes and piping. Rolling
of selected billets into 85 × 15 mm flats revealed occasional slivers, seams, and a few shallow hairline surface cracks. A
detailed metallurgical investigation was carried out to understand the genesis of these defects. A pearlite-free ferritic
microstructure near the cracks combined with the presence of dispersed inclusions resulting from internal oxidation in the
vicinity of cracks and the presence of scales within the shallow discontinuous short-length longitudinal cracks indicated
that these defects resulted from pre-existing subsurface blowholes lying within 1 mm of billet surface. Reduction of the gas
content of liquid steel in the mold, optimization of electromagnetic stirring (EMS) current, and control of superheat are
some of the broad measures identified to improve the cast quality of SUP 11A spring steel billets and minimize the rejection
of rolled flats. 相似文献
56.
Single carrier (SC) code division multiple access (CDMA) with block transmission has been shown to be more effective while utilising a low-complexity equaliser to combat frequency-selective fading channels, when compared with conventional direct sequence CDMA technology. It also has lower peak-to-average power ratio and lower frequency sensitivity compared with multicarrier CDMA. The authors propose two blind channel estimation methods for uplink multiple input multiple output SC-CDMA systems with block transmisssion-one is the subspace-based method and the other is the so-called autocorrelation contribution method (ACM). Both the methods provide close performance to the case with perfect channel knowledge at high signal-to- noise ratio (SNR) without any training data required. It is shown that ACM yields a better performance than the subspace method at a lower SNR, and a similar performance at a high SNR, with the advantages of avoiding rank determination and noise power estimation as in the subspace method. In addition, the authors integrate layered space frequency equalisation with blind channel estimation, which provides improved performance over the conventional linear equalisation, by employing successive interference cancellation. 相似文献
57.
58.
Das S Panda SK Nandi P Chaudhuri S Pandey A Ranganathan R 《Journal of nanoscience and nanotechnology》2007,7(12):4447-4455
Ni nanoparticles embedded in SiO2 matrix were prepared by sol-gel process. The molar percentages of Ni were varied from 2 to 20% of total SiO2 present in the matrix. Transmission electron microscope (TEM) images revealed that particle sizes varied from 8.0-15.7 nm at an annealing temperature of 773 K with variation of concentration. The optical absorption spectra revealed that the surface plasmon resonance (SPR) peak in the UV region of the spectrum shifted with the particle diameter (D) from that at 247.3 nm for D = 8.0 nm to 250.7 nm for D = 15.7 nm. In hysteresis loop measurements the magnetizations (M) of the nanocomposites also increased with higher Ni content in the matrix and did not saturate in the measuring limit of the magnetic filed (H) of 4 KOe. The anhysteric curves for different samples were analyzed with the law of approach to saturation (LAS). The zero field cooled (ZFC) and field cooled (FC) magnetization measurements at 50 Oe showed increasing broadening of the ZFC curve with the higher Ni content. To calculate the average blocking temperature ((T(B a distribution of the blocking temperatures (T(B)) was assumed to initiate theoretical fittings and it was found to be increasing with the Ni concentration in the matrix. 相似文献
59.
Application of PCA-based hybrid Taguchi method for correlated multicriteria optimization of submerged arc weld: a case study 总被引:1,自引:1,他引:0
Saurav Datta Goutam Nandi Asish Bandyopadhyay Pradip Kumar Pal 《The International Journal of Advanced Manufacturing Technology》2009,43(3-4):276-286
Fluid dispensing is a method by which fluid materials, such as epoxy, adhesive, and encapsulant, are delivered in a controlled manner in electronics packaging. This paper presents a brief review of past and recent developments in the modeling and control of the time-pressure fluid dispensing process. In particular, the characterization of the fluid flow behavior is addressed by reviewing several promising models from both time-independent and time-dependent perspectives. In the modeling of the time-pressure fluid dispensing process, various approaches for representing the flow rate of fluid dispensed and the profile of fluid formed on target are examined; and the issues involved are identified. In the control of time-pressure dispensing process, a brief review of various control methods is presented along with their limitations. The challenges associated with this control problem are also discussed. This paper is concluded with the recommendations of research in the future. 相似文献
60.
G. Pal U. Bhunia J. Akhter C. Nandi A. Datta P.R. Sarma S. Roy S. Bajirao S. Bhattacharyya T.K. Bhattacharyya M.K. Dey C. Mallik R.K. Bhandari 《低温学》2012,52(12):730-738
The quadrupole magnets for FAIR Super FRS energy buncher have large usable aperture, high magnetic pole-tip field and high gradient field quality. The iron-dominated magnets with superconducting coils have to be used in this application. The NbTi coil, laminated iron, and support structure of about 22 tons is immersed in liquid helium. The 4.5 K helium chamber is completely covered with a thermal shield cooled by helium at 50–80 K on its outer and inner surface. The helium chamber and thermal shield is enclosed in a vacuum shell.The paper presents design details of the long quadrupole. Coupled thermal, magnetic and structural analysis was carried out to design the magnet iron, magnet coil, helium vessel and support links and ensure the required gradient field quality is achieved. The paper also presents the design of support links and outer vacuum chamber. 相似文献