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排序方式: 共有74条查询结果,搜索用时 15 毫秒
1.
K. G. Satyanarayana K. K. Ravikumar K. Sukumaran P. S. Mukherjee S. G. K. Pillai A. G. Kulkarni 《Journal of Materials Science》1986,21(1):51-56
The stress-strain curves for pineapple leaf fibre have been analysed. Ultimate tensile strength (UTS), initial modulus (YM), average modulus (AM) and elongation of fibres have been calculated as functions of fibre diameter test length and test speed. UTS, YM, and elongation lie in the range of 362 to 748 MN m–2, 25 to 36 GN m–2, and 2.0 to 2.8%, respectively for fibres of diameters ranging from 45 to 205m. UTS Was found to decrease with increasing test lengths in the range 15 to 65 mm. Various mechanical parameters show marginal changes with change in speed of testing in the range of 1 to 50 mm min–1. The above results are explained on the basis of structural variables of the fibre. Scanning electron microscope studies of the fibres reveal that the failure of the fibres is mainly due to large defect content of the fibre bo1h along the fibre and through the cross-section, The crack is always initiated by the defective cells and further aggravated by the weak bonding material between the cells. 相似文献
2.
A. Sivashanmugam T. Prem kumar N. G. Renganathan S. Gopukumar 《Journal of Applied Electrochemistry》2004,34(11):1135-1139
In this work, we describe an evaluation of an Mg–Li alloy (Li: 13 wt %) for possible use in magnesium primary reserve batteries. Higher OCP for the Mg–Li alloy have been observed in 2 M MgCl2 and MgBr2 electrolyte. The corrosion rate of the Mg–Li alloy is found to be in the order: MgCl2 < Mg(COOCH3)2 < MgSO4 < MgBr2 < Mg(ClO4)2. Mg–Li alloys exhibit higher (81%) anodic efficiencies even when the current density is increased to 8.6 mA cm –2. It has been observed that Mg–Li/MgCl2/CuO cells offer higher operating voltage and capacity than those with the conventionally used Mg–Al alloy. 相似文献
3.
Sivashankaran Nair Sujatha Lekshmy Vijayam Sukumaran Nair Anitha PuthenKadathil Vargehese Thomas Kunjkunju Joy 《Journal of the American Ceramic Society》2014,97(10):3184-3191
Manganese‐doped tin oxide (SnO2:Mn) thin films were deposited on glass substrates by the sol–gel dip coating technique. The effect on structural, morphological, magnetic, electrical, and optical properties in the films with different Mn concentrations (0–5 mol%) were investigated. X‐ray diffraction patterns (XRD) showed the deterioration of crystallinity with increase in Mn‐doping concentration. Scanning electron microscopy (SEM) studies showed an inhibition of grain growth with an increase in Mn concentration. X ray photoelectron spectroscopy (XPS) revealed the presence of Sn4+ and Mn3+ in SnO2: Mn films. SnO2: Mn films show ferromagnetic and paramagnetic behavior. These SnO2:Mn films acquire n‐type conductivity for 0–3 mol% (SnO2 ‐ Sn0.97Mn0.03O2) ‐doping concentration and p type for 5 mol% Mn‐doping concentration(Sn0.95Mn0.05O2) in SnO2 films. An average transmittance of > 75% (in UV‐Vis region) was observed for all the SnO2:Mn films. Optical band gap energy of SnO2: Mn films were found to vary in the range 3.55 to 3.71 eV with the increase in Mn‐doping concentration. Photoluminescence (PL) spectra of the films exhibited an increase in the emission intensity with increase in Mn‐doping concentration which may be due to structural defects or luminescent centers, such as nanocrystals and defects in the SnO2. Such SnO2:Mn films with structural, magnetic and optical properties can be used as dilute magnetic semiconductors. 相似文献
4.
Layered LiMg0.1Co0.9O2 has been synthesized using microwave assisted solution technique. The precursor has been subjected to thermo-gravimetric/differential thermal analysis (TG/DTA) and calcined at 850 °C. The precursor and the calcined powders were characterized by X-ray diffraction (XRD) to confirm the formation of single-phase layered material. Fourier transform infrared (FTIR) studies were carried out to understand the nature of the metal-ligand bond and the observations were consistent with the XRD spectrum. Scanning (SEM) and transmission electron microscope (TEM) images have been obtained to understand the surface morphology and the grain orientation of the synthesized material. Coin cells of 2016 type have been assembled using the synthesized layered material as the cathode active material, lithium foil as the counter and reference electrodes and 1 M LiPF6 in 1:1 EC/DEC as the electrolyte. Coin cells were assembled and crimp sealed inside an argon filled glove box. The charge/discharge characteristics of the coin cells were evaluated galvanostatically in the potential range 2.7-4.3 V. Results indicate that LiMg0.1Co0.9O2 delivers an average discharge capacity of ∼135 mAh g−1 over the investigated 20 cycles and is a potential candidate for use as cathode material in lithium rechargeable cells. 相似文献
5.
Sukumaran Minu Amba Shetty Cécile Gomez 《International journal of remote sensing》2013,34(22):8246-8270
ABSTRACTVisible near-infrared and shortwave infrared data acquired by spaceborne sensors contain atmospheric noise, along with target reflectance that may affect its end applications, e.g. geological, vegetation, soil surface studies, etc. Several atmospheric correction algorithms have been already developed to remove unwanted atmospheric components of a spectral signature of Earth targets obtained from airborne/spaceborne hyperspectral image. In spite of this, choosing of an appropriate atmospheric correction algorithm is an ongoing research. In this study, two hybrid atmospheric correction (HAC) algorithms incorporating a modified empirical line (ELm) method were proposed. The first HAC model (named HAC_1) combines (i) a radiative transfer (RT) model based on the concepts of RT equations, which uses real-time in situ atmospheric and climatic data, and (ii) an ELm technique. The second one (named HAC_2) combines (i) the well-known ATmospheric CORrection (ATCOR) model and (ii) an ELm technique. Both HAC algorithms and their component single atmospheric correction algorithms (ATCOR, RT, and ELm) were applied to radiance data acquired by Hyperion satellite sensor over study sites in Australia. The performances of both HAC algorithms were analysed in two ways. First, the Hyperion reflectances obtained by five atmospheric correction algorithms were analysed and compared using spectral metrics. Second, the performance of each atmospheric correction algorithm was analysed for prediction of soil organic carbon (SOC) using Hyperion reflectances obtained from atmospheric correction algorithms. The prediction model of SOC was built using partial least square regression model. The results show that (i) both the hybrid models produce a good spectrum with lower Spectral Angle Mapper and Spectral Information Divergence values and (ii) both hybrid algorithms provided better SOC prediction accuracy, in terms of coefficient of determination (R2), residual prediction deviation (RPD), and ratio of performance to interquartile (RPIQ), with R2 ≥ 0.75, RPD ≥ 2, and RPIQ ≥ 2.58 than single algorithms. HAC algorithms, developed using ELm technique, may be recommended for atmospheric correction of Hyperion radiance data, when archived Hyperion reflectance data have to be used for SOC prediction mapping. 相似文献
6.
7.
GR Evans G Gherardini A Gürlek H Langstein GA Joly DM Cromeens AV Sukumaran J Williams RG Kilbourn B Wang T Lundeberg 《Canadian Metallurgical Quarterly》1997,100(6):1475-1481
Extreme arterial vasoconstriction (vasospasm) is a common problem encountered in microvascular surgery. An ideal pharmacologic tool able to counteract ischemia during microsurgery should be easy to apply and exert its action both locally and distally in the microcirculation of the flap. We have compared in vitro and in vivo vascular properties of nicardipine, papaverine, and lidocaine in the rabbit carotid artery. In vitro, rings from the rabbit carotid artery (n = 7) were bathed in Krebs-Ringers solution and stretched progressively to an optimal tension of 3.7 to 4.2 g. The specimens were contracted with norepinephrine (1 microM), and a cumulative dose response curve was established. In vivo, microvascular anastomoses were performed bilaterally in the rabbit carotid artery in 35 animals using 9-0 nylon suture and standard microsurgical techniques. During and after the anastomoses, nicardipine (0.1, 0.01 mg topical, or 0.1 mg/hour IV), papaverine (30 mg/cc topical), and lidocaine (2% with and without epinephrine) were applied (blinded) at the anastomotic site in five rabbits each. Heparinized sodium chloride was used as topical irrigation for control and to clean the anastomosis. Blood flow changes were monitored continuously with the transonic Doppler for 30 minutes after the procedure. The systemic blood pressure was also monitored in a group of pilot experiments. A documented decrease in blood flow was noted in all animals after the microvascular anastomosis. Nicardipine and papaverine evoked a concentration-dependent relaxation to precontracted rings to norepinephrine. Nicardipine was greater than papaverine in inducing relaxation. Lidocaine demonstrated a biphasic response with low concentrations potentiating contraction. Systemic nicardipine and papaverine significantly increased the blood flow in the rabbit carotid artery. Topical application of nicardipine and lidocaine did not significantly alter the blood flow; however, the application of nicardipine demonstrates a trend toward increased flow. Lidocaine with epinephrine significantly decreased the blood flow. No drug was found to alter the blood pressure of the animals. Our results demonstrate that nicardipine and papaverine seem to be pharmacologic tools able to increase the blood flow in anastomotic arteries. In contrast, the use of 2% lidocaine as a spasmolytic agent should be re-evaluated, since this substance may act as a partial agonist. 相似文献
8.
Jitendra B Misra Narakkat P Sukumaran Sirish C Verma 《Journal of the science of food and agriculture》1991,54(3):339-345
Cresolase and catecholase activities were determined in tubers of four potato (Solanum tuberosum L) varieties (Kufri Chamatkar, Kufri Chandramukhi, Kufri Sindhuri and C-2703) fertilised with three levels (0, 120, 240 kg K2O ha?1) of either muriate or sulphate of potash. The enzyme activities were also determined separately in the peel and flesh tissues of the tubers of Kufri Chamatkar and C-2703. Differences were observed in the activities between varieties, with highest specific activities in the tubers of Kufri Chamatkar. Peels of both the varieties showed higher cresolase and catecholase activities than the flesh tissue. Application of potassic fertilisers caused a reduction in both the activities in the tuber, peel and flesh tissue. Greater reduction in activities was caused by application of muriate of potash than with the sulphate form. 相似文献
9.
A relatively simple numerical iterative procedure for estimating the normal modes of flexural vibrations of a slender, multipanel latticed cantilever, tapered or straight, is developed. The cantilever is reduced to a N mass system and the influence coefficients are derived with due consideration to the shear flow through the diagonal bracings. Experimental and computer results on a model are compared. 相似文献
10.
A. G. Kulkarni K. G. Satyanarayana K. Sukumaran P. K. Rohatgi 《Journal of Materials Science》1981,16(4):905-914
Stress-strain curves of coir fibres have been determined. Mechanical properties including initial modulus, strength and percentage elongation of coir fibres have been evaluated as functions of retting treatment (during retting the coconut husks are soaked in saline water for a period of about six months to facilitate the extraction of fibres presumably due to a bacterial process), fibre diameter, gauge length and strain rate. No significant differences in mechanical properties were observed between retted and unretted fibres. The strength and percentage elongation seem to increase for both retted and unretted fibres up to a fibre diameter of 0.2×10–3 m whereafter they remain almost constant. On the other hand, moduli seem to decrease with increase in diameter of the fibre. The observed modulus values and percentage elongation have been related to microfibrillar angle. Observed strength values have been explained on the basis of structural changes occurring with an increase in the diameter of the fibre. Scanning electron/microscope studies have indicated that the failure of the fibre is due to the fracture of the cells themselves accompanied by the uncoiling of microfibrills. There is no appreciable variation in strength and percentage elongation with strain rates for any one diameter of the fibre. On the other hand, with increase in gauge length, a decrease in both strength and percentage elongation at break has been observed. These have been attributed to an increase of probability of defects and localized deformation and gentle necking, respectively. 相似文献