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排序方式: 共有174条查询结果,搜索用时 0 毫秒
61.
A new sliding bearing material based on rubber filled with different graphites was assessed against stainless steels of various structures under conditions of water lubrication in an Amsler machine. The tribological characteristics of the rubber-graphite depend upon the fillers used. The wear of stainless steel journals depends upon the material structure and the chromium carbide present. 相似文献
62.
Microcalorimetric measurements of heat related to fusion and crystallization of the eutectic in Fe-C and Fe-C-Si-Mn alloys have been carried out. In the case of Fe-C alloys, the heat related to fusion and crystallization of the eutectic changed from 0 to 215 kJ/kg and from 0 to 207 kJ/kg, respectively. For Fe-C-Si-Mn alloys, the heat related to fusion and crystallization of the eutectic changed from 178 to 220 kJ/kg and from 169 kJ/kg to 216 kJ/kg, respectively. This was attributed to the change of the content of eutectic in the alloys. 相似文献
63.
Two petrographic types of Tertiary brown coals, xylitic and earthy, were carbonized, and activated with carbon dioxide between 1123 and 1273 K. The development of porosity in the activated chars was studied by adsorption of benzene and carbon dioxide at 298 K and by mercury porosimetry. The type of brown coal exerts a dominant influence on the properties of the activated chars. The xylitic brown-coal, when compared with the earthy brown-coal, yields products with a higher pore volume and better sorptive properties. Activated chars from the xylitic brown-coal reach a surface area of 800 m2 g?1, contained principally in micropores and very narrow mesopores (radius below 3.0 nm). Dimensions of pores in the activated chars from the earthy brown-coal are less uniform, the mesopores are broader (an important part of them has a radius between 5.0 and 100.0 nm), and micropores are present to a smaller extent; the surface area of these products is between 200 and 350 m2 g?1. Activated chars from both types of brown coals have a well developed system of macropores. 相似文献
64.
Gryczynski I Malicka J Gryczynski Z Nowaczyk K Lakowicz JR 《Analytical chemistry》2004,76(14):4076-4081
Surface plasmon-coupled emission (SPCE) is the directional radiation of light into a substrate due to excited fluorophores above a thin metal film. To date, SPCE has only been observed with visible wavelengths using silver or gold films. We now show that SPCE can be observed in the ultraviolet region of the spectrum using thin (20 nm) aluminum films. We observed directional emission in a quartz substrate from the DNA base analogue 2-aminopurine (2-AP). The SPCE radiation occurs within a narrow angle at 59 degrees from the normal to the hemicylindrical prism. The excitation conditions precluded the creation of surface plasmons by the incident light. The directional emission at 59 degrees is almost completely p-polarized, consistent with its origin from surface plasmons due to coupling of excited 2-AP with the aluminum. The emission spectra and lifetimes of the SPCE are those characteristic of 2-AP. Different emission wavelengths radiate at slightly different angles on the prism providing intrinsic spectral resolution from the aluminum film. These results indicate that SPCE can be used with numerous UV-absorbing fluorophores, suggesting biochemical applications with simultaneous surface plasmon resonance and SPCE binding assays. 相似文献
65.
Ignacy Gryczynski Joanna Malicka Kazimierz Nowaczyk Zygmunt Gryczynski Joseph R. Lakowicz 《Thin solid films》2006,510(1-2):15-20
Surface plasmon-coupled emission (SPCE) phenomenon is the coupling of excited fluorophores near a silver film with surface plasmons, resulting in directional emission into the underlying glass substrates. We report a complex coupling of Nile Blue fluorophore with 50 nm silver mirror, resulting in emission at several angles in the glass substrate, with either s or p polarization. This complex pattern of directional and polarized emission appears to be due to optical waveguide effects occurring when the sample thickness becomes comparable to the emission wavelength. We expect waveguide-modulated SPCE to have applications to biophysics and sensing. 相似文献
66.
León-Santiestebán H Meraz M Wrobel K Tomasini A 《Journal of hazardous materials》2011,190(1-3):707-712
This study describes pentachlophenol (PCP) sorption in nylon fiber in which Rhizopus oryzae ENHE was immobilized to remove the chemical compound. The experimental sorption data were analyzed using the Langmuir, Freundlich, and Redlich-Peterson isotherm models using non-linear error functions to fit the experimental data to the three models. Results showed that the isotherm obtained from the data fitted the three models used. However, the g parameter from Redlich-Peterson model showed that the isotherm obtained approaches the Freundlich model. This support reached the sorption equilibrium concentration at 3mg PCPg(-1)nylon. To study PCP removal capability by R. oryzae ENHE and to eliminate the error caused by PCP sorbed by the nylon fiber during its quantification, nylon fiber at PCP equilibrium sorption concentration was used to immobilize R. oryzae ENHE. It was found that this fungus grew within nylon fiber cubes in presence or not of PCP, even when PCP caused growth inhibition. Maximum biomass accumulated into nylon cubes without PCP was of 32 mg biomass g(-1)nylon and into nylon cubes at PCP equilibrium concentration was of 18 mg g(-1)nylon. The results showed that R. oryzae ENHE immobilized into nylon fiber removed 88.6% and 92% of PCP in cultures with 12.5 and 25 mg PCPL(-1), as initial concentration, respectively. This is the first work to report that a zygomycete, such as R. oryzae ENHE, immobilized into nylon fiber kept its potential to remove PCP. 相似文献
67.
Gelca R Surowiec K Anderson TA Cox SB 《Journal of nanoscience and nanotechnology》2011,11(2):1225-1229
Fullerene C60, a class of carbon nanomaterials, is widely used and is likely to reach the environment. The degradation and transformation of C60 aqueous suspensions exposed to simulated sunlight were studied. C60 aqueous suspensions prepared by stirring pristine C60 in water under sunlight exposure undergo breakdown with formation of a mixture of compounds with unknown chemical structure. The mass and infrared spectrometric analysis of the breakdown products shows the presence of broken C60 cages, as well as of oxygen and hydrogen atoms in their structure. The presence of oxygen in the breakdown products indicates a possible interaction of C60 molecule with oxygen from the air as well as with water. Interaction with water could also explain the presence of H atoms in the breakdown products. This demonstrates that fullerenes C60 are not stable in the environment and that the breakdown products should be considered when evaluating the environmental impact of fullerenes C60. 相似文献
68.
The paper presents methodology and results of electrochemical examination of magnesium in 0.1 M NaCl solution with different pH. The measurements were conducted under potentiodynamic conditions using Dynamic Electrochemical Impedance Spectroscopy (DEIS). Analysis of DEIS results was performed based on electrical equivalent circuit. As the result of analysis changes of separate parameters of the equivalent circuit vs. potential for different pH values of the environment were obtained. Simultaneously with DEIS measurements an investigation using acoustic emission was conducted. The results showed that for pH higher than 12.50 the properties of layers on the surface of magnesium change significantly. One can observe a stable passive state that has properties considerably different from those of the layers that form in solutions with lower alkalinity. In such conditions the beginning of pitting corrosion process can be unequivocally determined by the level of acoustic emission and the values of electrochemical parameters. 相似文献
69.
The goal of the presented research was to determine the physicochemical properties of composite samples obtained by mixing BaCe0.85Y0.15O3−δ (BCY15) and Ce0.85Y0.15O2−δ (YDC15) in different ratios, and to achieve a better understanding of how these ratios affect the electrical conductivity, chemical stability and morphology of BCY15–YDC15 composite materials. It was determined that the samples are chemically stable in H2O-containing atmospheres at 600 °C. Furthermore, the porosity of the samples increases with the addition of YDC15 to BCY15. Both the porosity and the BCY15/YDC15 ratio affect the stability of the studied samples. The total activation energy (Et) values of the composite samples, determined via resistance measurements conducted in air at temperatures between 200 and 800 °C, are in the range of 0.590 ± 0.017 eV (Et of BCY15) to 1.132 ± 0.008 eV (Et of YDC15). This indicates that the properties of activation energy for composite materials are additive; the presence of both BCY15 and YDC15 affects the activation energy values. The different morphologies of the samples also influence the conductivity within the respective samples. The electrical conductivity values of the composite samples obtained at temperatures from 200 to 500 °C are in the order of magnitude of 10−7–10−3 S/cm. These values are between those determined for pure BCY15 and YDC15 at the respective measuring temperatures. Consequently, the materials show promise for application as porous central membranes (CM) in dual PCFC–SOFC fuel cells operating in the temperature range 600–700 °C. 相似文献
70.
Anna Wrona Veronika Aleksandrovych Tomasz Bereza Pawe Basta Anna Gil Magdalena Ulatowska-Biaas Magorzata Mazur-Laskowska Kazimierz Pityski Krzysztof Gil 《International journal of molecular sciences》2022,23(11)
Oxygen balance is crucial for angiogenesis, immunity, and tissue repair. The human oviduct is essential for reproductive function, and any imbalance in homeostasis leads to fertility disturbances and might be a reason for ectopic pregnancy development. Uterine myoma is a widespread benign tumour, which is often accompanied by infertility. Telocytes have been discussed in the contexts of motility, fibrosis development, and angiogenesis. We observed the oviducts from patients with and without uterine myoma, comparing the expression of HIF-1, HO, VEGF and its receptor, NOS, oestrogen, and progesterone receptors by immunolabeling. The myometrial and oviductal telocytes were also compared in both groups. Biochemical analyses were conducted for FSH, LH, AMH, sFlt, oestrogen, and progesterone in blood samples. Patients with uterine myoma have different expressions of sex steroid receptors and an increased number of telocytes. The decreasing VEFG expression was compensated by the rise in the HIF-1 and NOS expression. Blood biochemical analyses revealed a higher progesterone level and lower AMH in patients with uterine myoma. No differences in sFlt, FSH, and LF were observed. Uterine myoma impacts oviduct oxygen homeostasis and might cause fertility disturbances (uterine and oviductal infertility factors). 相似文献