707 research outputs found
The application research and practice of monographic teaching in graduate teaching
以化学工程与技术一级学科研究生的学位课《高等反应工程》为例,进行了专题研讨式课堂教学设计,以培养综合能力和素质为目标,进行了三届研究生课堂教学的应用实践与随堂问卷调查信息反馈,获得了学生的第一手信息资料,通过对反馈信息的分析与总结,提出了适应于工科学位课应用数学较多的研究生专题式研讨课教学模式,为下一步的工科学位课教学提供了重要参考。Studies on seminar-style teaching model was carried out by taking a senior course of chemical reaction engineering on the graduate level for first-level disciplines of chemical engineering and technology as an example. To develop comprehensive ability and quality, the questionnaire investigation and information feedback of three graduate students and classroom teaching practice was finished and the first-hand information of students was obtained. Through the analysis and summary of the feedback information, this paper puts forward the Monographic Teaching mode, which is suitable for the applied mathematics of engineering degree course, and provides an important reference for the next engineering degree course teaching
Biomechanics Characteristics of New Type Artificial Hip Joint
The structure, geometrical shape and material are the three main parts of the prostheses. This research focuses on the geometrical shape analysis. The geometrical shape of human natural femoral head is similar to the ellipse, but, the artificial femoral head is rotundity shape. There is difference between ellipse and rotundity femoral head. Two models are developed and analyzed in this paper under same conditions used Finite element analysis method. Based on the calculation results, it is shown that the ellipse shape femoral head have the similar characteristics to the natural joint than rotundity model. The ellipse has the more lowness stress distribution area and more small distortion magnitude than rotundity shape artificial femoral head. It should have the more kind effect replace rotundity femoral head with ellipse shape artificial formal head. Keywords: hip joint; prosthesis design; finite element analysis; biomechanic
Radio Polarization of BL Lacertae objects
In this paper, using the database of the university of Michigan Radio
Astronomy Observatory (UMRAO) at three (4.8 GHz, 8 GHZ, and 14.5 GHz) radio
frequencies, we studied the polarization properties for 47 BL Lacertae
objects(38 radio selected BL Lacertae objects, 7 X-ray selected BL Lacertae,
and two inter-middle objects (Mkn 421 and Mkn 501), and found that (1) The
polarizations at higher radio frequency is higher than those at lower
frequency, (2) The variability of polarization at higher radio frequency is
higher than those at lower frequency, (3) The polarization is correlated with
the radio spectral index, and (4) The polarization is correlated with
core-dominance parameter for those objects with known core-dominance parameters
suggesting that the relativistic beaming could explain the polarization
characteristic of BL Lacs.Comment: 5 pages, 3 figures, 1 table. PASJ, in pres
rac-2-{[1-(1-Adamantyl)ethyl]iminomethyl}-5-methoxyphenol
A novel Schiff base compound, C20H27NO2, was obtained by a condensation of rimantadine and 2-hydroxy-4-methoxybenzaldehyde. An intramolecular O—H⋯N hydrogen bond supports the phenol–imine tautomeric form. The adamantane and iminomethyl-4-methoxyphenol units are arranged in a folded conformation [C—N—C—C torsion angle = 110.9 (3)°]. In the crystal, highly hydrophobic adamantane moieties are inserted between the iminomethyl-4-methoxyphenol units in a sandwich-like arrangement along the c axis
Fingerprint and multi-component quantitative analyses for quality evaluation of Rhizoma coptidis steamed with rice wine
Purpose: To establish a method for the simultaneous determination of multi-components of Rhizoma coptidis steamed with rice wine (RCRW), and to provide a reference for assessing its standard of quality.
Method: Chromatographic separation was performed on a high performance liquid chromatography (HPLC) system to determine the characteristic fingerprint of RCRW. The mobile phase consisted of acetonitrile (A) and 0.1 % trifluoroacetic acid (B), with gradients of B as follows: 15 - 20 % from 0 – 30 min; 20 - 25 % from 30 - 50 min; 25 - 35 % for 50 - 60 min, and 35 % for 60 - 70 min.
Results: In the multiple reaction monitoring mode, eight components of RCRW were isolated by HPLCphoto-diode array (PDA) method. A fingerprint of the RCRW was established and 8 peaks were calibrated. The method was further validated in terms of linearity (R2 > 0.9993), precision (relative standard deviation, RSD < 1.51 %); repeatability (RSD < 2.98 %) and stability (RSD < 1.93 %). Mean recovery rate ranged from 96.2 to 103.8 %, while RSD values ranged from 0.92 to 2.88 %.
Conclusion: These results show that HPLC-PDA method is accurate and feasible, and that they provide a reference for further comprehensive and effective quality control of RCRW
Evolutionary Stages and Disk Properties of Young Stellar Objects in the Perseus Cloud
We investigated the evolutionary stages and disk properties of 211 Young
stellar objects (YSOs) across the Perseus cloud by modeling the broadband
optical to mid-infrared (IR) spectral energy distribution (SED). By exploring
the relationships among the turnoff wave bands lambda_turnoff (longward of
which significant IR excesses above the stellar photosphere are observed), the
excess spectral index alpha_excess at lambda <~ 24 microns, and the disk inner
radius R_in (from SED modeling) for YSOs of different evolutionary stages, we
found that the median and standard deviation of alpha_excess of YSOs with
optically thick disks tend to increase with lambda_turnoff, especially at
lambda_turnoff >= 5.8 microns, whereas the median fractional dust luminosities
L_dust/L_star tend to decrease with lambda_turnoff. This points to an
inside-out disk clearing of small dust grains. Moreover, a positive correlation
between alpha_excess and R_in was found at alpha_excess > ~0 and R_in > ~10
the dust sublimation radius R_sub, irrespective of lambda_turnoff,
L_dust/L_star and disk flaring. This suggests that the outer disk flaring
either does not evolve synchronously with the inside-out disk clearing or has
little influence on alpha_excess shortward of 24 microns. About 23% of our YSO
disks are classified as transitional disks, which have lambda_turnoff >= 5.8
microns and L_dust/L_star >10^(-3). The transitional disks and full disks
occupy distinctly different regions on the L_dust/L_star vs. alpha_excess
diagram. Taking L_dust/L_star as an approximate discriminator of disks with
(>0.1) and without (<0.1) considerable accretion activity, we found that 65%
and 35% of the transitional disks may be consistent with being dominantly
cleared by photoevaporation and dynamical interaction respectively. [abridged]Comment: 31 pages, 13 figures, 2 tables. To appear in a special issue of RAA
on LAMOST science
2-[1-(tert-Butoxycarbonyl)pyrrolidin-2-yl]-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl 3-oxide
In the title compound, C16H28N3O4, the plane of the pyrrolidine ring system is twisted with respect to the plane of the nitronyl nitroxide unit, making a dihedral angle of 79.80 (6)°. The crystal structure is stabilized by C—H⋯O hydrogen bonds
Influencing factors and clinical significance of the metastatic lymph nodes ratio in gastric adenocarcinoma
<p>Abstract</p> <p>Background</p> <p>To investigate influencing factors of the metastatic lymph nodes ratio (MLR) and whether it is related to survival in patients with gastric adenocarcinoma.</p> <p>Methods</p> <p>We retrospectively evaluated the clinical features of 121 patients with gastric adenocarcinoma enrolled in our hospital between 2000 and 2007. The receiver operating characteristic (ROC) curve was used to determine the cutoff of the MLR, and CK20 immunohistochemical staining was used to detect micrometastasis of the lymph nodes.</p> <p>Results</p> <p>The areas under the ROC curve of MLR used to predict the death of 3-year and 5-year postoperative patients were 0.826 ± 0.053 and 0.896 ± 0.046. Thus MLR = 30.95% and MLR = 3.15% were designated as cutoffs. The MLR was then classified into three groups: MLR<sub>1 </sub>(MLR<3.15%); MLR<sub>2</sub>(3.15% ≤ MLR ≤ 30.95%); and MLR<sub>3 </sub>(MLR>30.95%). We found that patients with a higher MLR demonstrated a much poorer survival period after radical operation than those patients with a lower MLR (P = 0.000). The COX model showed that MLR was an independent prognostic factor (P = 0.000). The MLR could also discriminate between subsets of patients with different 5-year survival periods within the same N stage (P < 0.05). The MLR has been shown to be 34.7% (242/697) by HE staining and 43.5% (303/697) by CK staining (P = 0.001). The clinicopathological characteristics of lymph vessel invasion and the depth of invasion could significantly affect the MLR.</p> <p>Conclusion</p> <p>MLR is an independent prognostic factor in gastric cancer. The combined ROC curve with MLR is an effective strategy to produce a curve to predict the 3-year and 5-year survival rates.</p
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