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51.
麻醉机是麻醉的最重要器械,是麻醉设备学的主要研究内容.通过该模型的演示学习可使麻醉医师全面掌握麻醉机的结构、性能、操作要点及其可能的故障和危险. 相似文献
52.
流感病毒感染引起免疫损伤的同时可以激发机体产生免疫应答,在病毒的清除与疾病的恢复及再次感染过程中发挥着有效的防御作用.尽管流感病毒经常发生变异,但自然感染诱导的免疫防御机制仍可提供一定程度的交叉保护作用.这一系列免疫应答的激发及形成包括多种分子及细胞的参与,其发生、发展及转归直接决定着疾病的严重程度及免疫预防的有效性.了解天然免疫应答、粘膜免疫应答及获得性免疫应答的激发与维持可为流感病毒的防治及疫苗的研制提供思路. 相似文献
53.
For planning or co-ordinating health services it is necessary to have reference points for evaluating similar departments
in which homogeneous or equivalent activities are carried out. It is also necessary to consider the cost/benefit of the services.
The paper presents several new indices of performance which may be applied to this problem and which enable quantitative comparisons
to be made between hospitals and between departments. These indices include assessment of electrical hazards and service ability
of equipment as well as the ratio of technical support staff to inpatient stay. The indices have been evaluated in a few large
hospitals and found to be an effective management tool. 相似文献
54.
Dynamic particle image velocimetry (PIV) was applied to the study of the flow field associated with prosthetic heart valves.
The results were compared with those of laser Doppler anemometry (LDA). Anatomically and antianatomically oriented Jyros (JR)
and St. Jude Medical (SJM) valves were compared in the mitral position to study the effects of valve design on the downstream
flow field. The experimental program used a dynamic PIV system utilizing high-speed, high-resolution video to map the true
time-resolved velocity field inside the simulated ventricle. This system was complemented by a study using the more traditional
LDA system for comparison. Based on the experimental data, the following general conclusions can be made. High-resolution
dynamic PIV can capture true chronological changes in the velocity and turbulence fields. It also produces very detailed velocity
and turbulence information comparable to the LDA results. In the vertical measuring plane that passes both the center of the
aortic and mitral valves (A-A section), the two valves (the SJM and the JR) show distinct circulatory flow patterns when the
valve is installed in the antianatomical orientation. Small differences in valve design can generate noticeable differences,
particularly during the accelerating flow phase. The SJM valve maintains a relatively high velocity through the central orifice;
the curved leaflets of the JR valve generate higher velocities with a divergent flow during the accelerating and peak flow
phases. In the velocity field directly below the mitral valve and normal to the previous measuring plane (B-B section), where
characteristic differences in valve design will be visible, symmetrical twin circulations were observed because of the divergent
nature of the flow generated by the two inclined half-disks installed in the antianatomical orientation. The SJM valve, with
a central downward flow near the valve, is contrasted with the JR valve, which has a peripheral downward circulation with
higher, turbulent stresses. 相似文献
55.
OBJECTIVE: To investigate the retraction time, forces, and torques applied to the football helmet during removal of the face mask with different face-mask removal tools. DESIGN AND SETTING: Subjects retracted the face mask of a football helmet mounted to a force platform in a laboratory setting. They removed a standard face mask by cutting or removing (or both) the lateral plastic loop straps using 4 different tools: the Trainer's Angel (TA), FM Extractor (FM), power screwdriver (SD), and Quick Release System (QR) in a counterbalanced fashion. SUBJECTS: Eighteen certified athletic trainers participated in this study. MEASUREMENTS: We started measuring time when the subject picked up the tool and ended when the face mask was in a fully retracted position. Maximum forces and torques were measured from the force platform during the retraction process. RESULTS: The SD and QR retracted the face mask significantly faster than the TA and FM. Forces producing superior-inferior translation were least with the SD. The SD and QR produced less lateral translation and rotation and lateral flexion moment than the TA and FM. The FM produced less torque in the lateral flexion moment than the TA. CONCLUSIONS: Tools that removed the loop straps (SD, QR) were faster and produced less force and torque on the helmet than the tools that cut through the loop straps (TA, FM). 相似文献
56.
Itoh K Naganawa Y Matsuzawa F Aikawa S Doi H Sasagasako N Yamada T Kira J Kobayashi T Pshezhetsky AV Sakuraba H 《Journal of human genetics》2002,47(1):29-37
Three novel missense mutations in the human lysosomal sialidase gene causing amino acid substitutions (P80L, W240R, and P316S)
in the coding region were identified in two Japanese sialidosis patients. One patient with a severe, congenital form of type
2 sialidosis was a compound heterozygote for 239C-to-T (P80L) and 718T-to-C (W240R). The other patient with a mild juvenile-onset
phenotype (type 1) was a homozygote for the base substitution of 946C-to-T (P316S). None of these mutant cDNA products showed
enzymatic activity toward an artificial substrate when coexpressed in galactosialidosis fibroblastic cells together with protective
protein/cathepsin A (PPCA). All mutants showed a reticular immunofluorescence distribution when coexpressed with the PPCA gene in COS-1 cells, suggesting that the gene products were retained in the endoplasmic reticulum/Golgi area or rapidly degraded
in the lysosomes. Homology modeling of the structural changes introduced by the mutations predicted that the P80L and P316S
transversions cause large conformational changes including the active site residues responsible for binding the sialic acid
carboxylate group. The W240R substitution was deduced to influence the molecular surface structure of a limited region of
the constructed models, which was also influenced by previously identified V217M and G243R transversions.
Received: Stptember 21, 2001 / Accepted: November 2, 2001 相似文献
57.
流感病毒感染引起免疫损伤的同时可以激发机体产生免疫应答,在病毒的清除与疾病的恢复及再次感染过程中发挥着有效的防御作用.尽管流感病毒经常发生变异,但自然感染诱导的免疫防御机制仍可提供一定程度的交叉保护作用.这一系列免疫应答的激发及形成包括多种分子及细胞的参与,其发生、发展及转归直接决定着疾病的严重程度及免疫预防的有效性.了解天然免疫应答、粘膜免疫应答及获得性免疫应答的激发与维持可为流感病毒的防治及疫苗的研制提供思路. 相似文献
58.
Differences in maintenance of CD8+ and CD4+ bacteria-specific effector-memory T cell populations 总被引:1,自引:0,他引:1
Schiemann M Busch V Linkemann K Huster KM Busch DH 《European journal of immunology》2003,33(10):2875-2885
Our knowledge about the kinetics and dynamics of complex pathogen-specific CD8(+) T cell responses and the in vivo development of CD8(+) memory T cells has increased substantially over the past years; in comparison, relatively little is known about the CD4(+) T cell compartment. We monitored and directly compared the phenotypical changes of pathogen (Listeria monocytogenes)-specific CD8(+) and CD4(+) T cell responses under conditions leading to effective and long-lasting protective immunity. We found that the general kinetics of bacteria-specific CD8(+) and CD4(+) T cells during the effector and post-effector phases are synchronized. However, later during the memory phase, CD8(+) and CD4(+) T cell populations differ substantially. Whereas CD8(+) memory T cell populations with immediate effector function are readily detectable in lymphoid and non-lymphoid tissues and remain remarkably stable in size, antigen-specific CD4(+) effector-memory T cells decline continuously in frequency over time. These findings have important implications for the better understanding of the in vivo development of protective immunity towards intracellular pathogens. 相似文献
59.
A simple, inexpensive device described here will produce a spike whose amplitude, shape, and output impedance are similar to those of the human QRS complex. Several reliable spike rates can be selected. 相似文献
60.