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排序方式: 共有557条查询结果,搜索用时 15 毫秒
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The records of 21 children with neuroblastoma presenting with spinal cord compression, encountered over 17 years, were reviewed. Thirteen patients (61%) survive, free of neuroblastoma, at intervals ranging from nine months to 192 months (median, 78 months) from the time of diagnosis. The explanation for this relatively high survival rate was sought in an analysis of the cases which took into account age, site, extent of disease, and histology. The most significant features to emerge were the unusually high proportion of children under 12 months of age at presentation (11 of 21) most of whom survive (9 of 11) and the low incidence (3 of 21) of detectable at the time of diagnosis. The absence of a paraspinal mass was an unfavourable prognostic features (1 of 6 survives) whilst if a paraspinal mass was present, its anatomical level did not influence survival. In particular, children with retroperitoneal tumors fared no worse (survival, 6 of 7) than those with primary tumors at other sites (survival, 6 of 8). Morbidity was high (6 of 13), principally in infants with spinal cord compression from birth. Survival was also related to the histologic maturity of the tumor, even in the presence of metastases. Recommendations for management are made. 相似文献
64.
H. Glockner M. Strscheletzky H. W. Hahnemann H. Gg. Wagner A. Kochendörfer W. Gerlach W. Hunsinger R. Friedl G. Eckart W. Schulz R. Schardt H. Haferkamp H. Glaubitz W. Koch 《Forschung im Ingenieurwesen》1958,24(1):33-36
Ohne Zusammenfassung
VDI 相似文献
65.
Effect of pressure on efficiency of UV curing of CVD-derived low-k material at different wavelengths
L. Prager P. Marsik M.R. Baklanov L. Pistol J.W. Gerlach M.R. Buchmeiser 《Microelectronic Engineering》2008,85(10):2094-2097
Low-k dielectrics prepared by CVD in the form of 200 nm thick layers on Si wafers were thermally treated at 410 °C and irradiated using UV lamps emitting photons of different wavelengths around 172 nm, 185 nm, and 222 nm. The treatment was performed in high vacuum and under a nitrogen atmosphere at various pressures ranging from 0.1 mbar up to 700 mbar. Subsequently, the samples were investigated using FTIR transmission spectroscopy, contact angle measurement, X-ray photoelectron spectrometry (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray reflectometry (XRR), surface acoustic wave spectrometry (SAW), and purged UV spectroscopic ellipsometry (PUVSE). It was found that for all UV wavelengths applied for curing the depth profiles of the chemical composition were homogeneous. For all properties evaluated, irradiation at wavelengths below 200 nm resulted in more pronounced changes than at longer wavelengths. Generally, a decrease in residual porogen content, conversion of the Si-O-Si bonds from cage to network/suboxide, degradation of Si-CH3 bonds, formation of H-SiO bonds, increase in surface energy, changes of element concentrations and of density, increase in Young’s modulus, and changes in dielectric constant were observed. These findings were confirmed by quantum-chemical calculations. With increasing nitrogen pressure the effects were more considerable. An attempt was undertaken to explain the effect of nitrogen pressure in course of the role of nitrogen molecules as collision partners. 相似文献
66.
Gunnar Suchaneck Vinay S. Vidyarthi Marianne Reibold Alexander Deyneka Lubomir Jastrabik Gerald Gerlach Johannes Hartung 《Journal of Electroceramics》2008,20(1):17-20
Pb(Zr,Ti)O3 (PZT) thin films deposited on insulating ZrO2 buffered silicon wafer are intended to be employed for in-plane polarized piezoelectric MEMS devices. Multi-target reactive
sputtering system for large area deposition of in-situ crystallized PZT thin films and the ZrO2 buffer layer has been employed. The interface analysis of multilayer structures by high resolution transmission microscope,
X-ray diffraction, optical refraction, and absorption spectra studies has been presented. At a substrate temperature of 520°C
and excess lead deposition condition, the formation of a PZT superstructure has been revealed. The substrate temperature of
580°C leads to the crystallization of PZT directly into a single phase perovskite crystal structure. A pronounced Urbach behavior
in our PZT thin films has been observed by optical absorption studies. The surface roughness of PZT films deposited on a ZrO2 buffer layer is much higher than that on conducting platinized silicon wafer. 相似文献
67.
Theory of Computing Systems - Given a hypergraph H = (V,E), what is the smallest subset $X \subseteq V$ such that e ∩ X≠∅ holds for all e ∈ E? This problem, known as the... 相似文献
68.
Ryan S. Hippman Ivan Pavlinov Qiwen Gao Michelle K. Mavlyanova Erica M. Gerlach Prof. Leslie N. Aldrich 《Chembiochem : a European journal of chemical biology》2020,21(21):3137-3145
A systematic, diversity-oriented synthesis approach was employed to access a natural product-inspired flavonoid library with diverse chemical features, including chemical properties, scaffold, stereochemistry, and appendages. Using Cell Painting, the effects of these diversity elements were evaluated, and multiple chemical features that predict biological performance diversity were identified. Scaffold identity appears to be the dominant predictor of performance diversity, but stereochemistry and appendages also contribute to a lesser degree. In addition, the diversity of chemical properties contributed to performance diversity, and the driving chemical property was dependent on the scaffold. These results highlight the importance of key chemical features that may inform the creation of small-molecule, performance-diverse libraries to improve the efficiency and success of high-throughput screening campaigns. 相似文献
69.
Florian Weyland Thorsten Eisele Sebastian Steiner Till Frömling George A. Rossetti Jürgen Rödel Nikola Novak 《Journal of the European Ceramic Society》2018,38(2):551-556
The stability of the electrocaloric effect under electric field cycling is an important consideration in the development of solid-state cooling devices. Here we report measurements carried out on Ba(Zr0.2Ti0.8)O3 ceramics which reveal that the adiabatic temperature change, polarization-electric field hysteresis loops and dielectric permittivity/loss show stable behavior up to 105 cycles. We further demonstrate that the loss in electrocaloric response observed after 105 cycles is associated with the migration of oxygen vacancies. As a result, the electrical properties of the material are changed leading to an increase in leakage current and Joule heating. Reversing the polarity of the electric field after every 105 cycles changes the migration direction of oxygen vacancies, thereby preventing charge accumulation at grain boundaries and electrodes. By doing so, the electrocaloric stability is improved and the adiabatic temperature remains constant even after 106 cycles, much higher than achieved in commercially available barium titanate ceramics. 相似文献
70.