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21.
韩寿岭 《辐射防护》1993,13(2):146-147
本文报道了某厂锆(Zr)生产流程中原料(锆英砂,主要成份为 ZrSiO_4)、半成品(ZrC,ZrCl_4)、废渣和成品锆中天然放射性核素~(238)U、~(226)Ra、~(232)Th 和~(40)K 含量测定结果。采用 NaI(Tl)γ能谱法进行测定,结果表明,原料、半成品和废渣中都含有一定的放射性,各生产环节应采取适当的防护措施;成品锆中基本不含放射性,可安全地应用于各个生产和生活领域。  相似文献   
22.
ElectronmicroscopicobservationsandDNAchainfragmentationstudiesonapoptosisinbonetumorcelsinducedby153SmEDTMPZhuShouPeng,Xia...  相似文献   
23.
The authors demonstrate, for the first time, a three node optically time division multiplexed network with a maximum capacity of 40 Gbit/s. Electro-optical switches were used for both `drop and insert' and demultiplexing, and electronic clock recovery provided synchronisation throughout the network  相似文献   
24.
Herein, we report an efficient process for preparing monodisperse Au@SiO2 nanoparticles using homogeneous shaking and without the use of surface‐coupling silane agents or large stabilizers. The resulting pure‐silica surface of the Au@SiO2 nanoparticles is very important for straightforward surface functionalization with different functional groups via well‐established silica surface chemistry. Subsequent covalent bioconjugation of the aldehyde‐functionalized Au@SiO2 nanoparticles with various biomolecules is successfully employed to make robust nanoprobes for fast, colorimetric DNA and protein detection based on the sequence‐specific hybridization properties of DNA and the specific binding affinity between proteins, respectively.  相似文献   
25.
Diagnosis and treatment of 17 patients who sustained 20 iatrogenic ureteral injuries were analyzed. Primary operations in which ureteral injury occurred are almost gynecologic procedures and general surgery. Injuries were managed by ureteroureterostomy in four, ureteral stent in one, removal suture ligation and ureteral double J-catheter in one, ureteroneocystostomy in ten, psoas-hitch technique and ureteroneocystostomy in one, nephrectomy in two. All patients with appropriate repair were followed-up periods of three to five years. Renal function of these patients had optimal results. When ureteral injury occurs, B-US, IVU, cystoscopy, retrograde ureterography or infusion of dye may be useful. An appropriate repair should be chosen according to length and position of ureteral injuries. Reoperation was optimal in two to three weeks. Immediate recognition of accidental ureteral injury provides optimal results. Patients with unrecognized injuries had suboptimal results.  相似文献   
26.
The employment of the Zn(Se,Te) pseudo-graded contacting scheme to p-type ZnSe-based alloys contributes directly to the recent demonstration of room temperature continuous-wave operation of II– VI green-blue laser diodes. Contact ohmicity is maintained down to cryogenic temperatures which enabled the investigation of electrical transport properties associated with the p-type nitrogen-doped ZnSe, Zn(S,Se), and (Zn,Mg)(S,Se). The observation of both persistent photoconductivity and a metastable population of holes which are in thermodynamic equilibrium with hydrogenic acceptors having reduced activation energy suggests the presence of a DX-like behavior for holes in p-type (Zn,Mg)(S,Se).  相似文献   
27.
在高职院校的软件项目实训环节中,大多项目需要团体协作进行编程。针对如果有效提高学生的协同编程效率、团队合作意识以及合作学习能力的问题,提出了基于Dillenbourg原则的协同编程方法。通过实践证明,该方法取得了良好的实训效果。  相似文献   
28.
Localized multiple kernel learning (LMKL) is an attractive strategy for combining multiple heterogeneous features in terms of their discriminative power for each individual sample. However, models excessively fitting to a specific sample would obstacle the extension to unseen data, while a more general form is often insufficient for diverse locality characterization. Hence, both learning sample-specific local models for each training datum and extending the learned models to unseen test data should be equally addressed in designing LMKL algorithm. In this paper, for an integrative solution, we propose a probability confidence kernel (PCK), which measures per-sample similarity with respect to probabilistic-prediction-based class attribute: The class attribute similarity complements the spatial-similarity-based base kernels for more reasonable locality characterization, and the predefined form of involved class probability density function facilitates the extension to the whole input space and ensures its statistical meaning. Incorporating PCK into support-vectormachine-based LMKL framework, we propose a new PCK-LMKL with arbitrary l(p)-norm constraint implied in the definition of PCKs, where both the parameters in PCK and the final classifier can be efficiently optimized in a joint manner. Evaluations of PCK-LMKL on both benchmark machine learning data sets (ten University of California Irvine (UCI) data sets) and challenging computer vision data sets (15-scene data set and Caltech-101 data set) have shown to achieve state-of-the-art performances.  相似文献   
29.
The equilibrium Ca3P2(s) = 3[Ca] + 2[P] was studied at 1600 ° by equilibrating liquid iron, saturated with Ca3P2, and contained in a TiN crucible, with Ca vapor. The source of Ca was liquid Ca contained in an Mo crucible, and the vapor pressure of Ca was varied by varying the position of the Mo crucible in the temperature gradient of a vertical tube furnace. A least-squares analysis of the data gave and. The simultaneous equilibria CaO(s) = [Ca] + [O] and CaS(s) = [Ca] + [S] were studied at 1600 ° by equilibrating liquid iron, contained in a pressed and sintered CaO-CaS crucible with Ca vapor. The advantage of this technique is that two equilibrium constants,K cas andK cao, and two interaction coefficients, and can be determined from one set of experiments. It was determined that, at 1600 °,K cas = 5.9 × 10−8 K cao = 5.5 × 10−9,, and. Formerly Graduate Students  相似文献   
30.
研究了一种制造低电电压氧化锌压敏电阻器的方法。在基本成分的基础上适当加入二氧化钛可降低梯度电压(V1mA/mm),适量掺硼和改进热处理工艺可减小元件的漏电流和提高其稳定性。  相似文献   
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