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91.
概述了乙醇氨解法等二乙胺的六类合成方法及国内外二乙胺的生产情况,指出了我国二乙胺生产技术与国外的差距,提出了扩大生产规模、开发下游产品、开发或引进加压加氢工艺等建议 相似文献
92.
High performance CMOS current comparator 总被引:1,自引:0,他引:1
A new high-speed CMOS current comparator is described. By changing the buffer of an existing comparator from class B to class AB operation, voltage swings are reduced, resulting in greater speed for small input currents. Simulation results employing a 1.6μm CMOS technology show the response time to a 0.1μA input current to be 11ns and the power dissipation to be 1.4mW, resulting in a five times improvement in speed/power ratio over existing high-speed current comparators 相似文献
93.
扫描电子显微研究表明,化学汽相沉积的金刚石薄膜中晶粒大小比较均匀。但随着沉积时间和薄膜厚度的增加,晶粒逐渐变大,且每一层内,存在少量的大金刚石颗粒,讨论了晶粒尺寸变化和大晶粒形成的原因和机制。 相似文献
94.
95.
N Cherradi MF Rossier MB Vallotton AM Capponi 《Canadian Metallurgical Quarterly》1996,271(42):25971-25975
In adrenal glomerulosa cells, angiotensin II (Ang II) stimulates aldosterone synthesis through rises of cytosolic calcium ([Ca2+]c). The rate-limiting step in this process is the transfer of cholesterol to the inner mitochondrial membrane, where it is converted to pregnenolone by the P450 side chain cleavage enzyme. The aim of the present study was to examine the effect of changes in [Ca2+]c and of Ang II on intramitochondrial cholesterol distribution. Freshly prepared bovine zona glomerulosa cells were submitted to a cytosolic Ca2+ clamp (600 nM) or stimulated with Ang II (10 nM). Mitochondria were isolated and subfractionated into outer membranes (OM), inner membranes (IM), and contact sites (CS). Cholesterol content was determined by the cholesterol oxidase assay. Stimulation of intact cells with Ca2+ led to a marked decrease in cholesterol content of OM (to 54 +/- 24% of controls, n = 5) and to a concomitant increase of cholesterol in CS and IM (to 145 +/- 14%, n = 5). When glomerulosa cells were exposed to Ang II, a marked increase of cholesterol in CS occurred (to 172 +/- 16% of controls, n = 5). No significant changes were detected in OM cholesterol, suggesting a stimulation of cholesterol supply to the mitochondria in response to Ang II. Cycloheximide specifically and significantly reduced Ca2+-activated cholesterol transfer to CS and IM. In conclusion, our data indicate that one of the main functions of the Ca2+ messenger is to increase cholesterol supply to the P450 side chain cleavage enzyme by enhancing endogenous intermembrane cholesterol transfer to a mitochondrial site containing the enzymes responsible for the initial steps of the steroidogenic cascade. 相似文献
96.
97.
98.
Patients with chlamydial infections (Ct) attending the outpatient Venereal Disease Clinic of Copenhagen from July 1-November 30 1995 were asked to fill in a questionnaire focusing upon knowledge, attitude and behaviour related to sexually transmitted diseases (STDs) in order to strengthen the future prevention of Ct. The questionnaire was answered by 37 men and 35 women with a median age of 27 and 21 years and a median number of three and two sexual partners within the last six months, respectively. Half of the patients had previously had an STD, and 92% had been tested for HIV, of whom one homosexual man was known HIV-positive. Notification about exposure from a partner was the reason for attending for 24%. All but one were in favour of partner notification, but only 6% wanted provider referral. During last intercourse condoms had neither been used with a steady partner by 75% especially by the young and women, who thought themselves safe, nor with a casual partner by 52% especially among the young and men, mainly because of thoughtlessness or perception of low risk. Before the actual STD diagnosis only 49% were able to name one symptom and 35% one complication related to Ct. A majority (79%) stated, that fear of catching another Ct would lead to better protection, and 70% found that more information would have a preventive effect. Future Ct prevention programs in Denmark should include intensified chlamydial screening and partner notification together with centrally produced mass media information supplemented by individual counselling. 相似文献
99.
EM Prvulovich JB Bomanji WA Waddington P Rudrasingham AM Verbruggen PJ Ell 《Canadian Metallurgical Quarterly》1997,38(5):809-814
1. Effects of feeding condition from birth were examined on the sensitivity of neuromuscular transmission to d-tubocurarine (dTc) in vitro in male mice of the ddY strain. 2. Mice were trained to climb two separated cylindrical steel-wire tubes for feeding and drinking, respectively, from 16 days of age. Some mice were conventionally fed, from 99 days of age. Nerve-muscle preparations were made from the left phrenic nerve diaphragm muscle (DPH), the sciatic nerve soleus muscle (SOL), and the sciatic nerve extensor digitorum longus muscle (EDL) of 99-day-old and 155-day-old mice. The nerve trunk was electrically activated with trains of four pulses and tetanic pulses. 3. The sensitivity to the effects of dTc decreased in the order EDL, SOL, and DPH. This result held true in all mice tested. 4. This sensitivity was significantly potentiated by the compulsory movement. 5. The supersensitivity remained even when mice were conventionally fed after 99 days of age. 6. The compulsion rendered EDL antifatigable on tetanic stimulation. This property was also retained after a return to conventional feeding. 7. These results suggest that the effects of feeding condition from birth might remain on neuromuscular functions after termination of the conditioning. 相似文献
100.
AM Molesworth 《Canadian Metallurgical Quarterly》1997,7(6):R77-R82
Health districts in England, Wales, and Northern Ireland were surveyed in 1996 to collect summary information about people with diagnosed HIV infection who received care under the statutory services in 1995. The survey provided demographic and epidemiological information about the prevalent caseload by area of residence, and the extent to which patients with diagnosed HIV infection travelled to obtain care related to it. A total of 13362 people with diagnosed HIV infection were reported to be resident and treated in England, Wales, or Northern Ireland in 1995. Forty-four per cent of these were treated outside the health district where they lived, with regional specialist centres attracting patients from wider areas. At least 13% received care from more than one treatment centre. This national survey of prevalent diagnosed HIV infections provided public health specialists with information relevant to their own localities without compromising confidentiality. This information complements surveillance data from confidential AIDS case diagnosis reports, laboratory reports of HIV infections, and the unlinked anonymous HIV prevalence monitoring programme, all of which contribute to the assessment and projection of demands on health and social services, and provide evidence on which to develop and direct national and local health campaigns. 相似文献