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排序方式: 共有425条查询结果,搜索用时 31 毫秒
41.
M Tryland T Sandvik L Holtet H Nilsen O Olsvik T Traavik 《Canadian Metallurgical Quarterly》1998,143(4):105-109
Hemangiomata is the more frequent pediatric tumor, absent at birth and usually growing, sometimes very quickly, during the first week of life. It potentially represents a serious problem because of his unforeseeable evolution during the time: is it more useful to use a corticosteroid therapy or to wait for the involution of the tumor? Here we have the results of the treatment on 51 babies who presented with hemangiomas of various sites: 52.6% of the lesions were on the face and head, 13.4% on chest wall, 10% on upper limbs, 4% on abdominal wall, 10% on pelvis region and 10% multiple. Therapy was compression in 10% of patients, corticosteroid injection in 66%, oral administered corticosteroid in 12%, surgery post corticosteroid therapy in 11.5%, others in 2.5%. Best results were obtained on the lesion of the head and face (good in 96%), worst in those of the abdomen (any modification in 100%). 相似文献
42.
Amyloidosis is characterized by deposition of protein fibrils in various tissues. The wide variety of sequences of both amyloidogenic and non-amyloidogenic immunoglobulin light chains makes them a unique tool for addressing the importance of primary structure in the formation of insoluble fibrils. In this study, we have determined the primary structure of the kappa I immunoglobulin light chain from both the urinary Bence Jones protein and the deposited amyloid fibrils of a patient (MH) with primary amyloidosis. The sequence identity of urinary-excreted and tissue-deposited light chains excluded biclonality and somatic mutations and confirmed that the light chain existed in both a soluble and an insoluble form. Several residues have been previously reported to be significantly associated with amyloidogenic kappa chains. Many of these were found in the MH sequence, including Asp31, Asn45, Phe49, Gln55, His70, Asn/Gly93 and ProN/Val96, thereby supporting their potential role in fibrillogenesis. In addition, Asn20 and Pro60 of protein MH replaced the normally conserved Thr20 and Ser60. Asn20 was glycosylated in both the Bence Jones and the amyloid fibril protein MH. Cumulative effects of amyloid-associated residues and glycosylation might have rendered the immunoglobulin light chain MH prone to fibril formation. 相似文献
43.
Raji Soundararajan Kelvin G. Lynn Salah Awadallah Csaba Szeles Su-Huai Wei 《Journal of Electronic Materials》2006,35(6):1333-1340
We have studied the defect levels in as grown and post growth processed cadmium telluride (CdTe) using thermoelectric effect
spectroscopy (TEES) and thermally stimulated current (TSC) techniques. We have extracted the thermal energy (Eth) and trapping cross section (σth) for the defect levels using the initial rise and variable heating rate methods. We have identified 10 different defect levels
in the crystals. Thermal ionization energy values obtained experimentally were compared to theoretical values of the transition-energy
levels of intrinsic and extrinsic defects and defect complexes in CdTe determined by first-principles band-structure calculations.
On the basis of this comparison, we have associated the observed ionization levels with various native defects and impurity
complexes. 相似文献
44.
45.
Up to 1996, 368 persons in Norway (population 4.3 million) had been reported as being HIV-infected because of intravenous drug use. 72 of these had developed AIDS and 59 had died from AIDS. HIV-testing is very common among drug users in Norway and new cases are rarely detected at treatment centres or at autopsy. Some 15-30 cases may still be undiagnosed. HIV spread very rapidly among drug users in Norway in 1984 and 1985, by around 100 new cases per year. Since then, the annual incidence has decreased from 30-40 cases in 1986 to 10-15 in 1995. Although the drug users seldom shared syringes even before the advent of the HIV epidemic, we believe that the public rehabilitation programmes, needle exchange programmes and health information have contributed to control HIV in this group. We expect an annual incidence of 10-15 cases the next five years. 相似文献
46.
47.
Spectrophotometers, as electro-mechanical-optical devices, perform at a finite level of accuracy. This accuracy is limited by such factors as monochromator design, detector linearity, and cost. Generally, both the diagnosis and correction of spectrophotometric errors require a number of calibrated standard reference materials and considerable effort and commitment on the part of the user. A technique using multiple linear regression has been developed, based on the measurement of several suitably chosen standard reference materials, to both diagnose and correct systematic spectrophotometric errors, including photometric zero errors photometric linear and nonlinear scale errors, wavelength linear and nonlinear scale errors, and bandwidth errors. The use of a single chromatic ceramic tile to correct systematic errors improved the colorimetric accuracy of a set of chromatic and neutral tiles by a factor of two for a typical industrial-oriented spectrophotometer. Greater improvement can be achieved by increasing the number of tiles and performing a separate regression at each measured wavelength., These techniques have been extremely useful in improving inter-instrument agreement for instruments with similar geometry. 相似文献
48.
Coals from major Australian fields considered as suitable hydroliquefaction feedstocks were hydrogenated in a 1 kg h?1 continuous reactor unit at reaction conditions 415–435 °C and 21 MPa using a stirred flow reactor with retention time of about 2 h. The effect of coal rank and the catalytic effects of disposable iron-based (red mud plus sulphur) catalysts were studied. The system was operated continuously with process-derived recycle solvent for up to 236 h. The time for a single pass of recycle solvent was estimated to be 20 h. Distillate oil yields in the range 35–53% on daf coal were obtained under catalytic operation. The heavier product oils were shown to contain predominantly aromatics, hydroaromatics and phenolics. This indicates that fairly severe hydro-treatment would be required to produce specification diesel and aviation turbine fuels. Recycle solvent composition was observed to stabilize in 2–4 passes after making a process change. These data compare favourably with those obtained on the same coals in larger pilot plants showing that this unit is capable of producing useful yield data. 相似文献
49.
This paper addresses the concept of model uncertainty within the context of risk analysis. Though model uncertainty is a topic widely discussed in the risk analysis literature, no consensus seems to exist on its meaning, how it should be measured, or its impact on the application of analysis results in decision processes. The purpose of this paper is to contribute to clarification. The first parts of the paper look into the contents of the two terms ‘model’ and ‘uncertainty’. On this platform it is discussed how focus on model uncertainty merely leads to muddling up the message of the analysis, if risk is interpreted as a true, inherent property of the system, to be estimated in the risk analysis. An alternative approach is to see the models as means for expressing uncertainty regarding the system performance. In this case, it is argued, the term ‘model uncertainty’ loses its meaning. 相似文献
50.
RANTES (regulated on activation, normal T expressed and secreted) is a member of the chemotactic cytokine (chemokine) beta subfamily. High affinity receptors for RANTES have been identified on a human monocytic leukemia cell line THP-1, which responded to RANTES in chemotaxis and calcium mobilization assays. Steady-state binding data analyses revealed approximately 700 binding sites/cell on THP-1 cells with a Kd value of 400 pM, comparable to that expressed on human peripheral blood monocytes. The RANTES binding to monocytic cells was competed for by monocyte chemotactic and activating factor (MCAF) and macrophage inflammatory protein 1 (MIP-1) alpha, two other chemokine beta cytokines. Although MCAF and MIP-1 alpha competed for RANTES binding to monocytes with apparent lower affinity (with estimated Kd of 6 and 1.6, nM respectively) both of these cytokines effectively desensitized the calcium mobilization induced by RANTES. The chemotactic response of THP-1 cells to RANTES was also markedly inhibited by preincubation with MCAF or MIP-1 alpha. In contrast, RANTES did not desensitize the THP-1 calcium mobilization and chemotaxis in response to MCAF or MIP-1 alpha. These results, together with our previous observations that RANTES did not compete for MCAF or MIP-1 alpha binding on monocytic cells, indicate the expression of promiscuous receptors on monocytes that recognize one or more cytokines within the chemokine beta family. 相似文献