首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   85篇
  免费   2篇
电工技术   1篇
化学工业   25篇
金属工艺   2篇
轻工业   8篇
无线电   6篇
一般工业技术   28篇
冶金工业   8篇
自动化技术   9篇
  2022年   2篇
  2021年   5篇
  2019年   1篇
  2018年   3篇
  2017年   1篇
  2016年   3篇
  2015年   3篇
  2014年   1篇
  2013年   5篇
  2012年   8篇
  2011年   7篇
  2010年   6篇
  2009年   3篇
  2008年   10篇
  2007年   7篇
  2006年   5篇
  2005年   1篇
  2004年   1篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1998年   2篇
  1997年   2篇
  1996年   2篇
  1993年   2篇
  1989年   1篇
排序方式: 共有87条查询结果,搜索用时 0 毫秒
21.
OBJECTIVE: To compare the efficacy of dopamine (DA) with that of norepinephrine (NE) in the treatment of refractory hypotension caused by tricyclic antidepressants (TCAs). METHODS: A retrospective analysis was used to compare blood pressure responses in concurrent case series of patients treated with vasopressors for TCA-associated hypotension. The patients were adults (aged > or = 16 years) treated at 2 urban teaching hospitals from 1983 to 1994. All patients were diagnosed as having TCA ingestion (positive serum toxicologic assay), were hypotensive [systolic blood pressures (SBPs) < or = 90 mm Hg], and required vasopressor therapy. The patients were grouped by initial vasopressor treatment (i.e., NE vs DA). RESULTS: There were 26 hypotensive adult patients who met study criteria. All 26 patients remained hypotensive after initial treatment of their TCA-associated hypotension with crystalloid infusion and alkalinization. The NE and DA groups were similar in age, sex, and proportion of patients with single and co-drug ingestion. The NE group, however, had a significantly lower average SBP at study entry (56 vs 74 mm Hg, p = 0.04). Nine of 15 (60%) patients responded to DA (5-10 micrograms/kg/min) and 11/11 (100%) patients responded to NE (5-53 micrograms/min). The difference in response rates was statistically significant (p = 0.02). Six patients in whom DA (max rate 10-50 micrograms/min/kg) failed to raise the SBP subsequently responded to NE (max rate 5-74 micrograms/ min) when this drug was later used. One patient receiving NE (12 micrograms/min) developed ventricular ectopy, successfully treated with lidocaine. There were no ischemic complications from either NE or DA. Patients who failed DA therapy tended to be older (39 vs 30 years, p = 0.08), to be more hypotensive at study entry (64 vs 81 mm Hg, p = 0.008), and to remain hypotensive even at higher doses of DA (24 vs 7 micrograms/min/kg, p = 0.002). CONCLUSION: While this was not a prospective randomized study, NE appears advantageous over DA as the first-line vasopressor agent for those patients who require vasopressor support in the setting of TCA-induced hypotension that is refractory to IV fluid and serum alkalinization.  相似文献   
22.
Thirty-three patients with severe systemic hypertension defined as a diastolic blood pressure (DBP) > or = 120 mm Hg were randomized in a single-blind fashion to be treated with either intravenous fenoldopam mesylate (FNP) or sodium nitroprusside (NTP). Fenoldopam mesylate and NTP infusion rates began at 0.1 microgram/kg/minute and 0.5 microgram/kg/minute, respectively and were titrated to achieve a goal DBP of between 95 and 110 mm Hg; or a reduction of at least 40 mm Hg if the baseline DBP was > 150 mm Hg. Fenoldopam mesylate (n = 15) reduced blood pressure from 217/145 +/- 6/5 to 187/112 +/- 6/3 mm Hg (P < .001) at an average infusion rate of 0.5 +/- 0.1 microgram/kg/minute. The average time to achieve goal DBP with FNP was 1.5 +/- 1.4 hours. Nitroprusside (n = 18) reduced blood pressure from 210/136 +/- 5/2 to 172/103 +/- 6/2 mm Hg (P < .001) at an average infusion rate of 1.2 +/- .24 micrograms/kg/minute. Nitroprusside response time averaged 2 +/- 2.5 hours. There was no significant difference between the magnitude of effect seen with either FNP or NTP; nor was there any difference observed in the adverse effect rates of the two agents. Fenoldopam mesylate and NTP demonstrate similar overall efficacy in the treatment of severe systemic hypertension.  相似文献   
23.
This study investigated the effect of early feeding mode on the neurological condition at 42 months. For this purpose, healthy pregnant women were recruited in Groningen and Rotterdam, The Netherlands. Children were healthy and born at term. At 42 months, the children were neurologically examined by means of the Touwen/Hempel technique. In addition to the clinical diagnosis, the neurological findings were interpreted in terms of optimality. Special attention was paid to the quality of movements in terms of fluency. In total, 200 (51%) exclusively breastfed(for > or = 6 weeks) and 194 (49%) formula-fed children were studied. Twelve (3%) 42-month-old children were considered to be neurologically mildly abnormal and 1 child was diagnosed as abnormal. No effect of the type of feeding was found on the clinical diagnosis or the neurological optimality. After adjustments for study centre and social, obstetric, perinatal and neonatal neurological differences, a beneficial effect of breastfeeding on the fluency of movements was found (odds ratio for non-optimal fluency 0.56; 95% confidence interval 0.37-0.85). The prolongation of full breastfeeding beyond 6 weeks did not influence the quality of movements. In conclusion, among Dutch preschool children, there was a small advantageous effect of full breastfeeding during the first 6 weeks of life on the fluency of movements.  相似文献   
24.
A 600-MHz VLIW digital signal processor (DSP) delivers 4800 MIPS, 2400 (16 b) or 4800 (8 b) million multiply accumulates (MMACs) at 0.3 mW/MMAC (16 b). The chip has 64M transistors and dissipates 719 mW at 600 MHz and 1.2 V, and 200 mW at 300 MHz and 0.9 V. It has an eight-way VLIW DSP core, a two-level memory system, and an I/O bandwidth of 2.4 GB/s. The chip integrates a c64X DSP core with Viterbi and turbo decoders. Architectural and circuit design approaches to achieve high performance and low power using a semi-custom standard cell methodology, while maintaining backward compatibility, are described. The chip is implemented in a 0.13-/spl mu/m CMOS process with six layers of copper interconnect.  相似文献   
25.
26.
The substitution of lead in the electronics industry is one of the key issues in the current drive towards ecological manufacturing. Legislation has already banned the use of lead in solders for mainstream applications (T M ≈ 220 °C), but the use of lead in the solders for high-temperature applications (>85% lead, T M ≈ 250-350 °C) is still exempt in RoHS2. The search for proper substitutes has been ongoing among solder manufacturers only for a decade without finding a viable low cost alternative and is the subject of intensive research. This article tries to map the current situation in the field of high-temperature lead-free soldering, presenting a short review of current legislation, requirements for substitute alloys, and finally it describes some existing solutions both in the field of promising new materials and new technologies. Currently, there is no drop-in replacement for lead-containing solders and therefore both the new materials and the new technologies may be viable solutions for production of reliable lead-free joints for high-temperature applications.  相似文献   
27.
28.
A novel two-stage spectrally flattened, high output power erbium amplified spontaneous emission (ASE) fibre source pumped using a single laser diode pump is reported. The source has a bandwidth of 80 nm with a 1 dB ripple and output power of +13 dBm (20 mW)  相似文献   
29.
Rapid and reliable detection, identification, and typing of bacterial species are necessary in response to natural or terrorist-caused outbreaks of infectious diseases and play crucial roles in diagnosis and efficient treatment. We report here two proteomic approaches with a high potential in the detection and identification of Coxiella burnetii, the causative agent of Q fever. The first of them starts with the acetonitrile (ACN) and trichloroacetic acid extractions of inactivated C. burnetii cells followed by the detection of extracted molecules and ions derived from the inactivated cells by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In the second approach, identification of the proteins extracted by ACN is accomplished after enzymatic digestion by electrospray tandem mass spectrometry coupled to a nanoscale ultraperformance liquid chromatography (LC-MS/MS). In order to observe morphological differences on the surface structures upon extraction, the inactivated and treated cells of the bacterium were examined by electron microscopy. The LC-MS/MS approach has allowed identification of 20 proteins in the ACN extracts of C. burnetii strain RSA 493 that were observed in more than 3 out of 10 experiments.  相似文献   
30.
A physical analysis of cavitation-based implosive breakage of solid particles focusing on practical application during fine particle disintegration in a liquid suspension is submitted in the present paper. The physical source of the cavitation dynamics phenomena involved is an extreme velocity gradient induced by an ultrahigh-energy liquid jet mixing together with a slow liquid suspension of milled particles. Extreme tensile stresses occurring at velocity gradients over 1000 ms?1mm?1 at the operating temperature of 65 °C generates high-intensity pure vapor cavitation in the degassed water dispersion with extreme values of impact pressure in the final of bubble implosions on particle surfaces.Preparation of silicon nanoparticles with median diameter approximately 148 nm using a newly developed “Water Jet Mill” (WJM) device is demonstrated in the present article as an example of application of the aforementioned disintegration method as well as of theoretical analysis of this method. The disintegration method is characterized by a high potential for milling of submicron particles with high efficiency.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号