首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23篇
  免费   2篇
化学工业   5篇
能源动力   3篇
轻工业   2篇
无线电   1篇
一般工业技术   3篇
冶金工业   10篇
自动化技术   1篇
  2021年   1篇
  2019年   1篇
  2018年   1篇
  2017年   1篇
  2016年   1篇
  2014年   1篇
  2011年   2篇
  2009年   1篇
  2008年   1篇
  2007年   2篇
  2003年   1篇
  2002年   1篇
  1999年   2篇
  1998年   2篇
  1997年   2篇
  1996年   1篇
  1994年   1篇
  1977年   1篇
  1975年   1篇
  1971年   1篇
排序方式: 共有25条查询结果,搜索用时 80 毫秒
1.
Laughing at oneself is considered a core component of the sense of humor in the theories of several authors. In McGhee's (1996) eight-step-training program of the sense of humor, laughing at oneself constitutes one of the most difficult levels. However, until now, only little empirical evidence on laughing at oneself exists. Using a multimethod approach, in the current study, 70 psychology students and a total of 126 peers filled in the Sense of Humor Scale (SHS, McGhee, 1996), containing as a subscale “Laughing at oneself”. In addition, the participants answered the Trait and State forms of the State-Trait-Cheerfulness-Inventory (STCI, Ruch, K?hler, & van Thriel, 1996; Ruch, K?hler, & van Thriel, 1997). They then were confronted with six distorted images of themselves. Facial responses of the participants were videotaped and analyzed using the Facial Action Coding System (FACS, Ekman, Friesen, & Hager, 2002). Four indicators of exhilaration were examined: (a) experienced funniness, (b) AU12 smiles, (c) Duchenne displays, and (d) laughter. Furthermore, fake and masking smiles were studied. Results demonstrated that self- and peer reports of “laughing at oneself” converged moderately. All four indicators of exhilaration were shown, but funniness and laughter seemed to be the most strongly related indicators. Trait cheerfulness and (low) seriousness, and a cheerful mood state formed further characteristics of persons who laugh at themselves. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
2.
3.
4.
In the face of the global energy challenge and progressing global climate change, renewable energy systems and components, such as fuel cells and electrolyzers, which close the energetic oxygen and carbon cycles, have become a technology development priority. The electrochemical oxygen reduction reaction (ORR) and the direct electrochemical carbon dioxide reduction reaction (CO2RR) are important electrocatalytic processes that proceed at gas diffusion electrodes of hydrogen fuel cells and CO2 electrolyzers, respectively. However, their low catalytic activity (voltage efficiency), limited long‐term stability, and moderate product selectivity (related to their Faradaic efficiency) have remained challenges. To address these, suitable catalysts are required. This review addresses the current state of research on Pt‐based and Cu‐based nanoalloy electrocatalysts for ORR and CO2RR, respectively, and critically compares and contrasts key performance parameters such as activity, selectivity, and durability. In particular, Pt nanoparticles alloyed with transition metals, post‐transition metals and lanthanides, are discussed, as well as the material characterization and their performance for the ORR. Then, bimetallic Cu nanoalloy catalysts are reviewed and organized according to their main reaction product generated by the second metal. This review concludes with a perspective on nanoalloy catalysts for the ORR and the CO2RR, and proposes future research directions.  相似文献   
5.
Thermal performance testing of flat-plate collectors   总被引:1,自引:0,他引:1  
Existing standards for testing the performance of flat-plate solar collectors are documented in ASHRAE 93 [ANSI/ASHRAE Standard 93-2003, 2003. Methods of Testing to Determine Thermal Performance of Solar Collectors, ISSN: 1041-2336, ASHRAE, Inc., 1791 Tullie Circle, Ne, Atlanta, GA30329], ISO 9806-1 [ISO Standard 9806-1:1994(E), 1994. Test Methods for Solar Collectors – Part 1: Thermal Performance of Glazed Liquid Heating Collectors Including Pressure Drop, ISO, Case Postale 56, CH-1211 Geneve 20, Switzerland] and EN12975-2 [European Standard EN12975-2:2001, 2001. Thermal Solar Systems and Components – Solar Collectors – Part 2: Test Methods, CEN, Rue de Stasart, 36, B-1050, Brussels]. The ASHRAE 93 standard requires an experimental determination of the steady-state collector efficiency under prescribed environmental conditions for a range of collector fluid temperatures. Each test requires a minimum of 20 min and 22 tests are required to fully characterize a collector’s thermal performance. The ASHRAE 93 testing procedure is further complicated by the fact that the prescribed weather conditions do not often occur in some locations, which prolongs the time required to conduct the performance tests for a given collector. The EN12975-2 collector test procedure provides an alternative transient test method that can be conducted over a larger range of environmental conditions. This paper compares the results obtained by applying the EN12975-2 standard with results obtained from the ASHRAE 93 steady-state tests for a well-designed single-glazed selective surface flat-plate collector. The collector thermal parameters, FR(τα)e and FRUL obtained by the two test methods show good agreement. The incident angle modifier coefficient determined in the ASHRAE method, which uses a separate test for this purpose, was found to be more accurate than that determined in the transient method according to the EN12975-2 standard, which obtains this value and all other collector parameters in the same step. This transient method, however, uses a refined collector model that includes specific terms for the wind speed dependence and the collector thermal capacitance, which are absent in the ASHRAE model. The long-term collector thermal performance as a part of a water heating system was simulated using the efficiency curves derived from each of the test methods. The solar fractions obtained by simulation are within 7% for both cases.  相似文献   
6.
Material properties, such as elasticity data at wide-ranging conditions of pressure and temperature, attract increasing attention for material and earth sciences. In particular, polycrystalline ceramics for next-generation photonic applications are nowadays fabricated by advanced syntheses techniques operating under elevated pressures and temperatures. Herein, the elastic properties of a synthetic transparent and reinforced aluminosilicate nanoceramic composed of triclinic kyanite with minor amounts of trigonal α-alumina crystals are investigated using in situ synchrotron X-ray diffraction and ultrasonic techniques at high-pressure (up to 11 GPa) and high-temperature (300-1500 K) conditions. This not only enables the determination of the equation of state (EoS) parameters by applying the pressure-volume-temperature (P-V-T) data to the high-temperature Birch-Murnaghan EoS but also yields the elastic moduli together with their P and T derivatives from the fit of the compressional and shear wave velocities to a finite strain EoS: KS0,300 = 186(2) GPa, KS0,300 = 7.2(6), (∂KS0,300/∂T)P = −0.023(2) GPa K−1, G0,300 = 125(1) GPa G0,300 = 2.3(2), (∂G0,300/∂T)P = −0.017(1) GPa K−1. On the basis of our acquired results, we propose to predict the elastic moduli of aluminosilicate ceramics by a linear function of the ratio of AlO6 octahedra and SiO4 tetrahedra within the constituting phases.  相似文献   
7.
8.
Current evidence suggests that melanogenesis is controlled by epidermal paracrine modulators. We have analyzed the effects of transforming growth factor-beta1 (TGF-beta1) on the basal melanogenic activities of B16/F10 mouse melanoma cells. TGF-beta1 treatment (48 h) elicited a concentration-dependent decrease in basal tyrosine hydroxylase and 3,4-dihydroxyphenylalanine (Dopa) oxidase activities, to less than 30% of the control values but had no effect on dopachrome tautomerase activity (TRP-2). The inhibition affected to similar extents the Dopa oxidase activity associated to tyrosinase-related protein-1 (TRP-1) and tyrosinase. This inhibition was noticeable between 1 and 3 h after the addition of the cytokine, and maximal after 6 h of treatment. The decrease in the enzymatic activity was paralleled by a decrease in the abundance of the TRP-1 and tyrosinase proteins. TGF-beta1 mediated this effect by increasing the rate of degradation of tyrosinase and TRP-1. Conversely, after 48 h of treatment, the expression of the tyrosinase gene decreased only slightly, while TRP-1 and TRP-2 gene expression was not affected. An increased rate of proteolytic degradation of TRP-1 and tyrosinase seems the main mechanism accounting for the inhibitory effect of TGF-beta1 on the melanogenic activity of B16/F10 cells.  相似文献   
9.
The pigment epithelium of the retina (RPE) is derived from the optic cup and is essential for function and development of the eye. We produced a transgenic mouse line that expresses simian virus (SV40) transforming sequences under control of the 1.4 kb tyrosinase-related protein 1 (TRP-1) promoter, targeting expression of T antigen (Tag) to the RPE. In transgenic embryos, RPE cells proliferated in the anterior part of the eye and near the optic nerve. This resulted in formation of tumors, which were pigmented and of epithelial origin. In 3 months-old mice, pigmented cells were detected in spleen and inguinal lymph nodes. In spleen, tyrosinase, TRP-1 and SV40 Tag were expressed and tyrosinase was enzymatically active. Pigmented regions were positive for an epithelial marker, cytokeratin. Cell lines were established from tumor and metastases and kept in culture for more than 2 months. These were pigmented, and maintained expression of tyrosinase, TRP-1, cytokeratin and SV40 Tag. This demonstrates that RPE tumor cells metastasize to lymph node and spleen. In conclusion, the metastasis from TRP-1/Tag RPE tumors towards spleen and lymph nodes serves as potential tool to investigate biology and metastasis of tumors derived from the pigment epithelium.  相似文献   
10.
Exposure of individual purified neurofilament (NF) proteins to AlCl3 alters their electrophoretic properties in a time- and concentration-dependent manner, as visualized by their failure to migrate into SDS gels. Co-incubation of purified high (NF-H) and middle (NF-M) but not low (NF-L) molecular weight NF subunits prevents this AlCl3-induced alteration in electrophoretic migration. This latter finding suggested that specific interactions between NF-H and NF-M other than filament formation influenced their interaction with AlCl3. Co-incubation of the 160 kDa alpha-chymotryptic cleavage product of NF-H (corresponding to the highly phosphorylated C-terminal sidearm domain) with native NF-M prevented alteration in subunit electrophoretic migration by AlCl3. By contrast, intact, dephosphorylated NF-H subunits were unable to prevent AlCl3-induced alteration of native NF-M electrophoretic migration. Taken together, these findings suggest that phosphate-dependent interactions between the sidearm extensions of NF-H and NF-M diminish the ability of AlCl3 to associate with either subunit in a manner that alters their electrophoretic migration. This interaction of NF-H and NF-M sidearms is SDS-sensitive, while AlCl3-induced alteration in electrophoretic migration of individual subunits is SDS-resistant. Addition of SDS to mixtures of NF-H and NF-M subunits disrupted the protective effect, and promoted AlCl3-induced alterations in subunit electrophoretic migration. These findings support and extend the current hypothesis that the ability of aluminum to interact with NF subunits is a function of subunit phosphorylation, assembly, and extent of neurofilament-neurofilament cross-linking.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号