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21.
Among cochlear implant candidates there are patients who have abnormal middle and/or inner-ear conditions that make them unsuitable for implantation. Insertion of a foreign body may also be contraindicated in the setting of an existing or potential intracranial communication, or when the ear is prone to infection. Five patients presented with such unfavorable conditions. These included a Mondini dysplasia with persistent cerebrospinal fluid leak, an atretic mastoid with meningocele, chronic otitis media, a transverse petrous bone fracture, and a temporal bone adenoma. All patients underwent subtotal petrosectomies and cochlear implantations. In four cases implantation was performed concomitantly with subtotal petrosectomy, while the remaining case required a two-stage procedure. No complications occurred. The technique is described in detail, and the cases and the indications for surgery are discussed. By obliterating and isolating the tympanomastoid cleft from the outer environment and utilizing the technique of subtotal petrosectomy, a broader spectrum of patients can now be implanted safely.  相似文献   
22.
BACKGROUND: The perfect preanesthesia medication and its ideal route of administration are still debated, but for pediatric surgical patients undergoing brief procedures, preanesthesia medication is frequently omitted because of the concern that it will prolong the child's recovery from anesthesia. The effects of nasally administered midazolam on anesthetic recovery and hospital discharge times were determined in 88 ASA physical status 1 and 2 ambulatory surgical patients undergoing a brief surgical procedure. METHODS: Using a randomized, double-blind, placebo-controlled design, 88 ambulatory surgical patients 10-36 months of age undergoing myringotomy and tube insertion were entered into the study. All patients were randomly assigned to one of three medication groups. One group received 0.2 mg/kg intranasal midazolam; a second group received 0.3 mg/kg intranasal midazolam; and the third group received intranasal saline drops. All patients were anesthetized with nitrous oxide, oxygen, and halothane administered via mask. The duration of anesthesia lasted between 9 and 10 min. After preanesthetic medication, the children were evaluated for ease of separation and induction of anesthesia. In addition, the time from when the anesthetic was discontinued until the child recovered from anesthesia and the time the child was discharged home were recorded by a nurse observer blinded to the patient grouping. RESULTS: Children receiving midazolam had smoother, calmer parent-child separation and anesthesia induction scores, and their anesthesia recovery times and hospital discharge times were the same as those receiving placebo. CONCLUSIONS: For children undergoing brief surgical procedures, nasal midazolam provides satisfactory anxiolysis without delaying anesthesia recovery and hospital discharge.  相似文献   
23.
In this work, two geopolymers were prepared by acid activation (GPAc) and alkaline activation (GPAl) approaches using volcanic ash (VA) as the precursor material. The geosorbents were characterized by X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Fourier-transform infrared and Brunauer-Emmett-Teller (BET) surface area analyses and their comparative adsorptive potential for anionic (Eriochrome Black T/EBT) and cationic (methylene blue/MB) dyes from water is herein reported for the first time. GPAl and GPAc had 74.47 and 42.75 m2/g BET surface areas, respectively. Equilibrium adsorption data were described by the isotherm models in the order Freundlich > Sips > Langmuir model. Relative to acid activation (GPAc), alkaline activated geopolymer (GPAl) had the highest adsorption capacity for both MB and EBT, estimated at 952 mg/g and 251 mg/g, respectively, consistent with the BET surface areas. The adsorption rates were best described by the pseudo-second order (PSO) kinetic model. GPAl exhibited faster adsorption kinetics than GPAc as denoted by the adsorption half-life, t1/2. The thermodynamic functions indicated that the adsorption of both MB and EBT onto the geopolymers was spontaneous, exothermic and feasible. The adsorption was pH-dependent implying electrostatic interactions is the dominant driving mechanism of adsorption. The results show that alkaline activated geopolymers are better sorbents for dye removal than acid activated geopolymers under the examined conditions.  相似文献   
24.
The influence of the partial substitution of Co by Ti in the LaCoO3 perovskite system is studied by evaluating the electrical conductivity, the Seebeck coefficient and the thermal conductivity of the compounds up to T = 1273 K. The X-ray diffraction patterns of the LaCo1?xTixOδ (0.01 ? x ? 0.5) phases show two structural modifications depending on the Ti content. Compounds with x < 0.3 crystallize in the rhombohedrally distorted perovskite structure while samples with x ? 0.3 possess an orthorhombic unit cell. The oxidation state of the Co ions is studied by X-ray absorption near edge structure (XANES) spectroscopy. A negative thermoelectric power is found in the LaCoO3 system for low level Ti substitution (x = 0.01). In contrast, samples with higher Ti content show a large positive Seebeck coefficient, indicating positive majority charge carriers in the system. The electrical resistivity of the studied materials reveals a semiconducting-like behaviour. The lattice thermal conductivity was found to be low and nearly temperature-independent. The samples exhibit very small crystallite sizes in the range of few nanometres. Therefore, the low thermal conductivity can be assigned to an enhanced phonon scattering on grain boundaries.  相似文献   
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26.
The cytoskeleton of the parabasalid protozoan Holomastigotoides was investigated by epifluorescence, scanning confocal, and transmission electron microscopy using antibodies to centrin, tubulin, and MPM-2 epitopes. Previous microscopic analysis of Holomastigotoides spp. has shown that up to 10,000 flagella are arranged in 2-8 spiral bands encircling the cell. Spindle poles are associated with two flagellar bands. Sheets of cytoplasmic microtubules (MTs) called axostyles originate in the cell apex and extend to the cell base. Antibodies to centrin, a member of the EF-hand family of calcium-binding proteins, labeled a number of structures in Holomastigotoides, namely axostyles, the mitotic spindle, and portions of flagellar bands. The identity of these structures was confirmed by transmission electron microscopy and by immunofluorescence microscopy using antibodies to tubulin and MPM-2 epitopes. Antibodies to tubulin labeled MTs in basal bodies, flagella, axostyles, and the mitotic spindle. MPM-2 antibodies labeled spindle poles and short segments of flagellar bands to which the spindle poles are attached. Centrin is known to show calcium-sensitive contractile behavior. The pattern of flagellar band staining by antibodies to centrin was affected by [Ca2+]. In detergent-extracted cell fragments, the centrin staining pattern could be changed by changing [Ca2+]. This Ca2+ effect was modulated by a monoclonal antibody to centrin (20H5), indicating that centrin plays a role in altering flagellar band structure. These results show that centrin is located in key positions for maintaining cell polarity and directing cell movement through interactions with other cytoskeletal elements. Calcium may regulate the morphology of centrin-containing structures.  相似文献   
27.
28.
Natural zeolite of the clinoptilolite type (CT, particle size up to 200 μm) and its modified forms with different content (0.06-5%) of pharmaceutically active compounds (type of flavonoids): quercetin (Q) and quercetin dihydrate (QD) have been investigated by thermal analyses TG, DTA and DTG, FTIR spectroscopy, fluorescence spectroscopy, X-ray powder diffractometry, determination of the surface areas and the pore volumes by low-temperature adsorption of nitrogen and atomic force microscopy. The analyses checked the presence of Q or QD in modified zeolitic products (CTQ and CTQD).Natural zeolite of the clinoptilolite type and their modified forms CTQ and CTQD with low content (0.06% and 1%) of Q and QD have been used for the study of their anticancer activity. Carcinoma cell lines Jurkat, CEM, HeLa, MCF7, A549 and MDA were treated with various amounts of natural clinoptilolite and their modified forms CTQ and CTQD. The water content of the channel system influences the cytotoxicity of zeolite. The results of the study of pure CT thermally activated at two different temperatures 110 and 400 °C confirmed the better cytotoxicity of CT activated at 110 °C (CT110) with higher content of water in comparison with CT activated at 400 °C (CT400). Clinoptilolite modified with quercetin dihydrate (CTQD) has shown better cytotoxicity compared with clinoptilolite modified with quercetin (CTQ).  相似文献   
29.
A Bi-15 at.%Sb alloy, homogenized by equal channel angular extrusion (ECAE) at T = 523 K, has been treated just above its solidus temperature, causing segregation of a secondary Bi-rich phase at the grain boundaries. This process results in an in situ composite. The thermoelectric properties of the composite have been measured in the range of 5 K < T < 300 K. The results are compared with those of the homogeneous alloy. The presence of a Bi-rich phase improves the Seebeck coefficient at T < 50 K, and enhances the electrical conductivity by a factor of 1.4 at T = 300 K up to a factor of 3.4 at T = 50 K; unfortunately, the thermal conductivity also increases by about 50% in the same temperature range. As a result, the figure of merit, Z, is slightly suppressed above T = 110 K, but increases at lower temperatures, reaching a peak value of 4.2 × 10−3 K−1 at T = 90 K. The power factor considerably increases over the whole temperature range, rendering this material suitable as the n-type leg of a cryogenic thermoelectric generator for cold energy recovery in a liquefied natural gas plant.  相似文献   
30.
In this work, NaBH4+2MgH2 doped by ZrF4 was prepared by the ball-milling method. The structure and the morphology of different systems were characterized by X-ray diffraction and scanning electron microscopy. The thermodynamic properties of hydrogen release were determined by temperature-programmed desorption and differential scanning calorimetry. Hydrogen desorption kinetic properties and hydrogen content were investigated by pressure composition isothermal method. The main objective of this work was to study the relationship between the heat of hydrogen release and the quantity of hydrogen released by In-situ calorimetry measurement. The NaBH4+2MgH2+0.1ZrF4 can release about 7.4 wt.% H2 by two steps. Firstly, the heat of hydrogen release of the first and the second steps were lower by 480.82 J·g?1 and 430.8 J·g?1 than that of NaBH4+2MgH2, respectively. And the dehydrogenation enthalpy of NaBH4+2MgH2 went from ?243.81 kJ·mol?1 to ?191.2 kJ·mol?1. Secondly, the addition of ZrF4 can improve the hydrogen release kinetic property of NaBH4+2MgH2, which can release 5 wt.% H2 in 2.5 h at 385 °C under 0.01 MPa hydrogen pressure. Therefore, NaBH4+2MgH2+0.1ZrF4 will be a potential candidate as a fuel cell hydrogen supply system.  相似文献   
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