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101.
采用X射线光电子能谱(XPS)对电沉积Ni-W合金镀层表面膜进行了分析。研究结果表明,Ni-W合金镀层表面存在一层薄的氧化膜,而钨的氧化作用远大于镍,Ni-W合金镀层中W含量的提高对耐蚀性起决定作用。  相似文献   
102.
In this paper we describe a framework for analysing the creation and justification of Research & Development. The 4S framework is developed for analysing the scope, scale, skills and social network aspects of Research & Development value. The framework is based on social system theory, a process contingency model, and recent Research & Development metrics. We present a first empirical assessment based on a workshop using the 4S framework for leveraging Research & Development. Results that assist in the assessment of value creation utilising R & D within networks are very relevant in high tech industries. The multi–dimensional process approach of this framework seems promising for understanding and managing R&D value creation, but needs further operationalisation. Case studies are described and a Dutch network on leveraging R&D has been initiated.  相似文献   
103.
We investigated cell proliferation and cell death in the olfactory epithelium (OE) of mice from birth to maturity using bromodeoxyuridine and terminal deoxynucleotidyl transferase nick end labeling. We show that cell death events and proliferative activity diminish concomitantly with age in the OE. Thus, the age-dependent and coordinate diminution in cell proliferative activity and cell death events may serve to maintain the thickness of the OE as mice mature and age.  相似文献   
104.
OBJECTIVE: To describe a mother and her 2 sons affected by idiopathic intracranial hypertension (IIH), associated in the sons with root irritation symptom. Unlike the other 4 families reported previously, obesity was not present in our patients. DESIGN: Case reports. SETTING: Department of pediatrics in a university school of Medicine, Naples, Italy. PATIENTS: A mother (aged 36 years) and her 2 sons (aged 14 and 9 years) developed IIH at different times. Neuroimaging showed an empty sella in the mother, while IIH was associated with spinal and radicular pain in her 2 sons. The mother and the younger son developed permanent visual loss. CONCLUSIONS: Ophthalmologic follow-up in our patients indicates that IIH is a chronic disease. Surgical treatment should be considered an option.  相似文献   
105.
偏心渐开线齿轮在高速包装机上的应用   总被引:4,自引:0,他引:4  
采用偏心渐开线齿轮传动作为高速包装机横封机构,与其它变速传动机构相比,这种机构不仅结构简单,拆装方便,而且速度变化范围较大,传动较平稳,容易进行动平衡。从而能较好地改善封头和切刀的寿命。它最诱人的优点是容易制成可调变速范围的结构,以慢适应不同的物料和包装材料,并且它的制造成本非常低,与普通齿轮传动的制造成本几乎相同。  相似文献   
106.
Early diagnosis of local and distant recurrences of colorectal cancer remains difficult and there is no agreement on the effectiveness of follow-up in these patients. The aim of this study is to assess the value of our method of follow-up. We consider 239 patients with colorectal cancer and at least 2 years follow-up following radical resection. A local recurrence appeared in 26 patients (10.9%), a distant metastasis in 41 (17.1%), while in seven (2.9%) local and distant recurrences appeared simultaneously. Local recurrence was detected because of an increase in carcinoembryonic antigen (CEA) level in 15 patients (57.7%), during a scheduled endoscopy in four (15.4%) and because of symptoms in seven (26.9%). In seven patients (26.9%) a radical resection was possible. Distant metastases were detected by CEA levels in 20 patients (48.8%), by ultrasonography (U.S.) in 12 (29.3%) and by chest X-ray in five (12.2%). In 13 of 26 patients with liver metastases a resection was performed. This study shows that few patients benefit from follow-up and only CEA levels and liver U.S. performed intensively between 15 and 36 months after surgery are useful in early detection of recurrences. A modification of the follow-up to the single patient, according to the stage, location and grading of cancer, could improve the results, so lowering the costs of this expensive practice.  相似文献   
107.
Direct monitoring of the free Ca2+ concentration in the sarcoplasmic reticulum (SR) was carried out in rat skeletal myotubes transfected with a specifically targeted aequorin chimera (srAEQ). Myotubes were also transfected with a chimeric aequorin (erAEQ) that we have demonstrated previously is retained in the endoplasmic reticulum (ER). Immunolocalization analysis showed that although both recombinant proteins are distributed in an endomembrane network identifiable with immature SR, the erAEQ protein was retained also in the perinuclear membrane. The difficulty of measuring [Ca2+] in 100-1000 microM range was overcome with the use of the synthetic coelenterazine analogue, coelenterazine n. We demonstrate that the steady state levels of [Ca2+] measured with srAEQ is around 300 microM, whereas that measured with erAEQ is significantly lower, i.e. around 200 microM. The effects of caffeine, high KCl, and nicotinic receptor stimulation, in the presence or absence of external calcium or after blockade of the Ca-ATPase, were investigated with both chimeras. The kinetics of [Ca2+] changes revealed by the erAEQ were similar, but not identical, neither quantitatively nor qualitatively, to those monitored with the srAEQ, indicating that at this stage of muscle development, differences exist between SR and ER in their mechanisms of Ca2+ handling. The functional implications of these findings are discussed.  相似文献   
108.
The a.c. conductivity of the proteins lysozyme and subtilisin, both in their active and inactive or inhibited forms were determined theoretically. For this, quantum mechanical calculations and a random walk theory were used. The conclusions are that these enzymatic proteins can easily transport electrons which is most probably important in their role as catalysators of biochemical reactions. The electron transport is sensitive to three-dimensional changes of the active sites of these enzymes which have more flexibility than the whole molecule. Therefore, the flexibility of the active sites of enzyme catalysts is not only important for the conformational fitting with the reactants, but also strongly influences the transport in biochemical reactions.  相似文献   
109.
Time dispersion (TD) is computed for large neutron detectors using plastic scintillators. It is shown that TD seen by the photomultiplier (PM) tube does not necessarily increase with incident neutron energy, which is a result not fully in agreement with the usual finding  相似文献   
110.
We report two cases of metastatic non-functioning pancreatic endocrine tumour with very elevated plasma levels of alpha-fetoprotein. In these two cases, serial plasma levels of alpha-fetoprotein, initially normal, correlated well with hepatic tumour progression and were associated with fatal outcome. These results suggest that elevated plasma concentration of alpha-fetoprotein may be caused by metastatic pancreatic endocrine tumour and than alpha-fetoprotein serial measurement may be useful in prognostic evaluation.  相似文献   
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