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11.
The diamond chemical vapor deposition (CVD) process has been investigated theoretically and the morphological instabilities associated with the growth of diamond films have been examined with a model based on the continuum species conservation equation coupled to surface reaction kinetics. A linear stability analysis and numerical calculations have been carried out to determine critical parameters affecting the diamond deposition layer morphology. A two-dimensional model describes the evolution of the gas-solid interface. The dynamic behavior of the interface depends on the reactants' diffusivity and surface kinetics. These factors depend upon the reactant material properties and film growth conditions such as the reactor temperature and pressure. From the analyses, it has been found that the ratio (
/k) of gas phase diffusivity (
) to the surface reaction rate constant (k) plays the critical role in promoting diamond morphological instabilities because the film morphology stabilizing processes of surface diffusion and re-evaporation are absent or negligible during diamond CVD. It is found that the film nonuniformity increases as the ratio (
/k) decreases. Increasing growth rates also result in increasing morphological instability, leading to rough surfaces. It is shown that increasing reactor pressure and decreasing gas-phase temperature and/or substrate temperature promote deposition layer nonuniformity. An approach to avoiding these instabilities is proposed. 相似文献
12.
T. Mahalingam Soonil Lee Hanjo Lim Hosun Moon Yong Deak Kim 《Solar Energy Materials & Solar Cells》2006,90(15):2456-2463
Gallium arsenide (GaAs) is one of the important materials used for the fabrication of light emitting diodes, solar cells, microwave devices, etc. In the present work, electrodeposition of GaAs was successfully carried out potentiostatically from an aqueous solution mixture of gallium chloride (GaCl3) and arsenic oxide (As2O3). The optimum deposition potential, pH and bath temperature to synthesize GaAs thin films are found to be −0.8 V versus SCE, 2.0±0.1 and 60 °C, respectively. The effects of solution pH, bath temperature and deposition potential on the gallium content of GaAs films are studied. Photoelectrochemical (PEC) solar cells using n-GaAs photo-anode in a polysulphide electrolyte is constructed and I–V, C–V studies are carried out. Various semiconductor parameters such as, flat-band potential, band bending, donor density, depletion layer width are evaluated and the results are discussed. 相似文献
13.
Mark Daley Ian McQuillan James M. McQuillan Kalpana Mahalingam 《Natural computing》2011,10(2):795-804
Transposable genetic elements are prevalent across many living organisms from bacteria to large mammals. Given the linear
primary structure of genetic material, this process is natural to study from a theoretical perspective using formal language
theory. We abstract the process of genetic transposition to operations on languages and study it combinatorially and computationally.
It is shown that the power of such systems is large relative to the classic Chomsky Hierarchy. However, we are still able
to algorithmically determine whether or not a string is a possible product of the iterated application of the operations. 相似文献
14.
Han Joon Kwon S. Thanikaikarasan Thaiyan Mahalingam Kyung Ho Park C. Sanjeeviraja Yong Deak Kim 《Journal of Materials Science: Materials in Electronics》2008,19(11):1086-1091
Iron diselenide (FeSe2) is an interesting p-type semiconductor with a band gap of 1 eV suitable for solar cell applications. Deposition of FeSe2 thin films by electrodeposition from aqueous solutions is a low temperature and inexpensive technique. In the present work,
FeSe2 thin films were deposited onto tin oxide coated conducting glass substrates by cathodic electrodeposition technique. The
deposited films were characterized by X-ray diffraction, Energy dispersive X-ray analysis, Scanning electron microscope and
optical absorption techniques. The effects of electrolyte concentration and deposition potential on the structural, compositional,
morphological and optical properties of FeSe2 thin films are studied. The experimental observations are discussed in detail. 相似文献
15.
TR Mahalingam S Vijayalakshmi RK Prabhu A Thiruvengadasami CK Mathews KR Shanmugasundaram 《Canadian Metallurgical Quarterly》1997,57(3):191-206
Blood is one of the widely used specimens for biological trace element research because of its biological significance and ease of sampling. We have conducted a study of the blood of the Kalpakkam township population for trace and minor elements. For this purpose, analytical methods have been developed and standardized in our laboratory for the elemental analysis of blood plasma and red cells. Inductively coupled plasma-mass spectrometry (ICP-MS), a relatively new technique, has been applied for the analysis of trace elements. Details regarding spectral interference and matrix interference encountered in the analysis of blood and the methods of correcting them have been discussed. Flame atomic absorption spectrometry (AAS)/atomic emission spectrometry (AES) has been applied for the determination of minor elements. Precision and accuracy of these methods have also been discussed. 相似文献
16.
17.
Zachary Lingley Krishnamurthy Mahalingam Siyuan Lu Gail J. Brown Anupam Madhukar 《Nano Research》2014,7(2):219-227
We report on a cross-sectional high resolution transmission electron microscope study of lead sulfide nanocrystal quantum dots (NCQDs) dispersed on electron-transparent silicon nanopillars that enables nearly atomically-resolved simultaneous imaging of the entire composite: the quantum dot, the interfacial region, and the silicon substrate. Considerable richness in the nanocrystal shape and orientation with respect to the substrate lattice is observed. The average NCQD-substrate separation is found to be significantly smaller than the length of the ligands on the NCQDs. Complementary photoluminescence measurements show that light emission from PbS NCQDs on silicon is effectively quenched which we attribute to intrinsic mechanisms of energy and charge transfer from PbS NCQDs to Si. 相似文献
18.
Kuppani Sathish Hemalatha Mahalingam Kadiri Padmaja Ramesh Makala N. Rama Krishnaiah 《International Journal of Communication Systems》2024,37(9):e5776
In the case of future access networks, such as 6G-based applications, the free-space optical communication (FSO) technology is an efficient solution. FSO in 6G is extremely popular because of its unique properties, which include ease of installation, high bandwidth, high security, license-free long range, and interference resistance. However, environmental disturbances have a negative impact on the FSO system's functioning. Because of these atmospheric turbulences, the optical information gets restricted, which in turn reduces the link reliability, power density, and distance. This paper proposes a hybrid FSO strategy for improving system efficiency to address these problems. Signal creation is fundamental to every successful communication system. The FSO system consists of three components: the transmitter, the channel medium, and the receiver. The transmitter section includes a continuous wave laser, a Mach–Zehnder modulator, a nonreturn to zero transpose Walsh code generator, and a nonreturn to zero pulse generator. Wavelength division multiplexing-optical code division multiple access-spectrum slicing (WDM-OCDMA-SS) is used to facilitate efficient data transfer after signals have been generated by alternate mark inversion (AMI). In order to boost a weak signal, fused Raman erbium amplifiers (Fuse-RE) are used. Q factor and log bit error rate (BER) are used to assess the performance of the suggested approach. The proposed model has obtained a log BER of −15.3291 for clear air and a Q factor of 8.2922, whereas the performances are implemented using Python. The proposed approach achieves better performance when compared to the existing methodologies. 相似文献
19.
H Mahalingam J Vaughn J Novotny JR Gruber RM Niles 《Canadian Metallurgical Quarterly》1996,168(3):549-558
Serotonergic neuronal networks are important for food intake and body weight regulation. Dexfenfluramine (dF), a serotonin releaser and reuptake inhibitor, was used to investigate changes in food intake, body weight development, energy expenditure, respiratory quotient, and substrate oxidation rates for 12 days. Rats, which had been made obese by early postnatal overfeeding, received an energy-controlled mash diet and water ad lib and were intraperitoneally injected daily with either saline, 5 or 10 mg dF/kg. Compared to controls, food intake, body weight development, and energy expenditure were decreased in a dose-dependent manner, especially during the first 6 days. Lipid oxidation was increased while oxidation of carbohydrates was decreased. Pair-feeding experiments over 2 days revealed that this was not solely a result of diminished food intake but also an additional metabolic effect of dF, different from its anorectic effect. At the end of these experiments, plasma glucose and liver glycogen were unchanged after dF, but plasma free fatty acids were significantly decreased. Insulin-sensitivity was probably improved, indicated by decreased insulin levels and increases in muscle glycogen contents and activities of muscle pyruvate kinase. Liver-glutamine and contents of valine, leucine, and isoleucine in the muscle were significantly decreased after dF-treatment, the latter indicating a diminished proteolysis. The plasma tryptophan/large neutral amino acids ratio of the dF-rats was unchanged but that of the paired-fed rats was changed, despite similar changes in food intake. It is concluded that both increased oxidation of endogenous fat and reduced food intake could mediate the body weight reducing effect of dF. 相似文献
20.
Pucha R.V. Hegde S. Damani M. Tunga K. Perkins A. Mahalingam S. Ramakrishna G. Lo G.C. Klein K. Ahmad J. Sitaraman S.K. 《Advanced Packaging, IEEE Transactions on》2004,27(2):438-452
The next-generation convergent microsystems, based on system-on-package (SOP) technology, require up-front system-level design-for-reliability approaches and appropriate reliability assessment methodologies to guarantee the reliability of digital, optical, and radio frequency (RF) functions, as well as their interfaces. Systems approach to reliability requires the development of: i) physics-based reliability models for various failure mechanisms associated with digital, optical, and RF Functions, and their interfaces in the system; ii) design optimization models for the selection of suitable materials and processing conditions for reliability, as well as functionality; and iii) system-level reliability models understanding the component and functional interaction. This paper presents the reliability assessment of digital, optical, and RF functions in SOP-based microsystems. Upfront physics-based design-for-reliability models for various functional failure mechanisms are presented to evaluate various design options and material selection even before the prototypes are made. Advanced modeling methodologies and algorithms to accommodate material length scale effects due to enhanced system integration and miniaturization are presented. System-level mixed-signal reliability is discussed thorough system-level reliability metrics relating component-level failure mechanisms to system-level signal integrity, as well as statistical aspects. 相似文献