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   99篇
  免费   2篇
电工技术   8篇
化学工业   15篇
金属工艺   9篇
机械仪表   1篇
建筑科学   1篇
能源动力   2篇
轻工业   6篇
水利工程   2篇
无线电   8篇
一般工业技术   18篇
冶金工业   24篇
原子能技术   6篇
自动化技术   1篇
  2022年   1篇
  2021年   4篇
  2020年   6篇
  2019年   2篇
  2018年   4篇
  2017年   1篇
  2016年   5篇
  2015年   1篇
  2014年   1篇
  2013年   2篇
  2012年   3篇
  2011年   5篇
  2010年   3篇
  2009年   3篇
  2008年   2篇
  2007年   1篇
  2006年   3篇
  2005年   2篇
  2004年   1篇
  2001年   2篇
  1999年   4篇
  1998年   7篇
  1997年   8篇
  1996年   4篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   2篇
  1990年   1篇
  1989年   1篇
  1986年   1篇
  1985年   2篇
  1983年   4篇
  1982年   1篇
  1981年   2篇
  1978年   2篇
  1977年   3篇
  1976年   1篇
  1975年   1篇
排序方式: 共有101条查询结果,搜索用时 15 毫秒
1.
ABSTRACT

It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of nuclear data libraries. The series benchmark experiments were performed at a DT neutron source facility, OKTAVIAN of Osaka University, Japan, by the unique experimental system established by the authors’ group, which can extract only the contribution of large-angle scattering reactions. This system consists of two shadow bars, target plate (iron), and neutron detector (niobium). Two types of shadow bars were used and four irradiations were conducted for one experiment, so that contribution of room-return neutrons was effectively removed and only large-angle scattering neutrons were extracted from the measured four Nb reaction rates. The obtained experimental results were compared with calculations for five nuclear data libraries including JENDL-4.0, JEFF.-3.3, FENDL-3.1, ENDF/B- VII, and recently released ENDF/B-VIII. It was found from the comparison that ENDF/B-VIII showed the best result, though ENDF/B-VII showed overestimation and others are in large underestimation at 14 MeV.  相似文献   
2.
This paper provides a fundamental analysis of a power supply and rectifiers for wireless power transfer using magnetic resonant coupling (MRC). MRC enables efficient wireless power transfer over middle‐range transfer distances. MRC for wireless power transfer should operate at a high frequency in the industry science medical band, such as 13.56 MHz, because the size of the transfer device decreases at higher transfer frequencies. Therefore, the output frequency of the power supply on the transmitting side should be 13.56 MHz. In addition, the rectifier on the receiving side is operated at a high frequency. This paper focuses on the reflected power in the power supply and rectifiers. Thus, the parametric design method is clarified for the power supply, including a low‐pass filter to match the output, the impedance of the power supply with the characteristic impedance of the transmission line. In addition, the effects on the rectifiers of silicon carbide and gallium nitride diodes are confirmed by performing an experiment and a loss analysis.  相似文献   
3.
PURPOSE: To report the disappearance of traumatic macular hole in three eyes of three patients. METHODS: Clinical data of the patients were reviewed. RESULTS: The three patients were relatively young, ranging in age from 12 to 18 years old. In one eye of each patient, a small traumatic macular hole was observed at the first visit. Visual acuities ranged from 20/100 to 20/40. The macular holes resolved spontaneously 3 to 4 months after the trauma, and final visual acuity improved to 20/20 in all patients. CONCLUSION: Small traumatic macular holes in young patients can resolve spontaneously, and this can be associated with good visual recovery.  相似文献   
4.
We examined the relationships between maximum oxygen uptake (Vo2max) and cardiovascular risk factors including age (year), systolic blood pressure (mmHg), diastolic blood pressure (mmHg), serum total cholesterol level (mg/dl), serum high-density lipoprotein level (mg/dl), serum triglyceride level (mg/dl), blood glucose level (mg/dl), serum uric acid level (mg/dl), body fat (%bw), Body Mass Index (BMI), alcohol (points/day), cigarettes (/day), and physical activity (METs.exercise time/30 days). The alcohol point was defined as follows: beer 633ml = a glass of whiskey and water - sake 180ml = 1 point, and totaled at 30 days. The subjects of our study were 162 males (aged 40.6 +/- 13.1) and 133 females (aged 41.3 +/- 11.1) who underwent medical and physical examinations at the Fukui Industrial Health Center from April, 1991 to June, 1992. As a result of simple correlation analysis in males, Vo2max had significantly negative correlations with age (r = -0.223, p < 0.01), systolic blood pressure (r = -0.228, p < 0.01), diastolic blood pressure (r = -0.239, p < 0.01), or serum triglyceride level (r = -0.258, p < 0.001), serum uric acid level (p < 0.05), body fat (r = -0.230, p < 0.01), and BMI (r = -0.312, p < 0.001), and was positively correlated with physical activity (r = -0.249, p < 0.01). On the other hand, in females, age (r = -0.224, p < 0.01), systolic blood pressure (r = -0.222, p < 0.01), diastolic blood pressure (r = -0.267, p < 0.01), serum triglyceride level (r = -0.261, p < 0.001), body fat (r = -0.280, p < 0.01), and BMI (r = -302, p < 0.001), had significantly negative correlations with VO2max. However, partial correlations were tested after controlling body fat, BMI, cigarette, alcohol, physical activity, and age, none of the factors correlated with VO2max significantly. These findings suggest that the risk factors for cardiovascular diseases are related to VO2max, and the life style has an influence on these correlations. Thus, VO2max may be a comprehensive indicator for health promotion among the working population. Furthermore a longitudinal study is required to determine whether the increase in VO2max is related to the improvement in the risk of cardiovascular diseases.  相似文献   
5.
The durability of a cold wall MHD generator consisting of metal electrodes and alumina-coated peg insulators was experimentally examined in the oil-fired MHD condition with the additive of SO2 corresponding to S = 0.54 wt%. The structure of the electrode wall and various anode and cathode materials were tested, with particular reference to developing long-life electrodes. It was clarified that Pt, SHOMAC (28.8 Cr−1.9 Mo) and SUS-304 as anodes and W---Cu (70 W−30 Cu) and WC---Ag (60 WC−40 Ag) alloys as cathodes were promising for durability and that the structure of an anode divided into two elements connected to each other with an SnO2 resistor was very useful for uniformity of the anode corrosion pattern and the inter-anode voltages. It is reasonable to expect, from the test results, that the lifetime of a cold wall MHD generator in an oil-fired commercial plant will be over 4000 h, and therefore, a foundation for its commercial use has been established.  相似文献   
6.
We report a case of acute cholangitis caused by the inadvertent ligation of the right hepatic duct during a cholecystectomy performed 11 years before. When the condition of the right hepatic duct or accessory bile duct ligation persists for more than several years, resulting in atrophy of the relevant part of the liver, bile duct ligation will rarely cause severe clinical problems. However, acute cholangitis may occur, as in our patient, so long-term follow-up of the patient is warranted.  相似文献   
7.
We investigated whether beta-amyloid (Abeta)-like immunoreactivity was seen in the brains of newborn piglets. The immunoreactivity for Abeta(1-42) and Abeta(1-40) proteins, but not Abeta precursor protein, was present in CD68-positive perivascular cells of the hippocampus and in parts of the meninges. It was colocalized with immunoreactivity for receptor for advanced glycation end product and tumor necrosis factor-alpha. The protein with a molecular mass of 27 kDa, which was recognized by the Abeta antibodies, was identified as triosephosphate isomerase (TPI) with sequence homology to Abeta peptides by N-terminal amino acid sequencing, mass fingerprint analysis using matrix-associated laser desorption/ionization mass spectrometry, and Western blotting. Western blotting assay also revealed that detectable expression of Abeta proteins were not seen in the piglet brains. These findings indicate that TPI with sequence homology to Abeta peptides accumulates in perivascular cells of the microglia/macrophage lineage located around arterial vessels of the newborn piglet hippocampus.  相似文献   
8.
Periodic flooding alters riverine vegetation community composition; moderate flood disturbance maintains communities at an early seral stage, whereas severe floods may remove entire communities. After disturbance, plants may recolonize riverbeds from refugia.Here, we investigated the morphological characteristics of refugia where riverine plants survived large floods. At three sites, plant communities growing on cobble-bars were surveyed, and the hydraulic characteristics of each site were analyzed. The populations of an indicator plant, Anaphalis margaritacea sub-species yedoensis (Franch. et Savat.) were assessed after major floods in 2004 and 2009. At each survey, the particle size and bed composition were measured, and the critical shear-stress required to move particles at each site was calculated. A one-dimensional flow and the average and local shear-stress at ten different discharges, including that of the largest flood were calculated. The results demonstrate that the A. margaritacea community is maintained at locations where the local shear-stress at peak discharge in large-floods does not exceed a critical value. These conditions were achieved in locations with particular morphological characteristics, where the river is not constrained by levees and is restricted by a downstream narrow-pass; in this reach river width increases with discharge thus limiting the increase in water depth with increasing discharge and allowing the establishment of refugia where plant species may survive large floods.Flooding and reestablishment from refugia maintain a characteristic riverbed community in equilibrium.  相似文献   
9.
This paper proposes a power integrity control technique for dynamically controlling power supply voltage fluctuations for a device under test (DUT), and demonstrates its effectiveness for eliminating the overkills/underkills due to the difference of power supply impedance between an automatic test equipment (ATE) and a practical operating environment of the DUT. The proposed method injects compensation currents into the power supply nodes on the ATE system in a feed-forward manner such that the ATE power supply waveform matches with the one on the customer’s operating environment of the DUT. A method for calculating the compensation current is also described. Experimental results show that the proposed method can emulate the power supply voltage waveform under a customer’s operating condition and eliminate 95 % of overkills/underkills in the maximum operating frequency testing with 105 real silicon devices. Limitations and applications of the proposed method are also discussed.  相似文献   
10.
The Concorde trial compared immediate (Imm) with deferred (Def) AZT monotherapy in asymptomatic HIV-positive participants. Haematological and immunological markers and weight were measured throughout, and correlated with clinical endpoints. Markers associated with disease progression (CD4 lymphocyte count and percentage, platelets, p24 antigen and beta 2 microglobulin favoured Imm: those associated with toxicity (haemoglobin, neutrophils and white cell count) favoured Def. CD8 and total lymphocyte count did not differ significantly between groups. In multivariate analysis, the combination of baseline CD4, p24 antigen and beta 2m was the best baseline predictor of disease. Including change in CD4 and beta 2m at 12 weeks, or changes over follow-up in these markers significantly improved the fit. Markers were also incorporated into the definition of 'clinical' endpoints. Hazard ratio estimates from end-points that included CD4 < 50 and CD4 < 25 were closest to those for AIDS or death alone, but added very few extra events. Use of other landmark CD4 counts (100 or greater) or relative decreases in counts (25% or more) increased the number of events, but overestimated the effect of immediate AZT. Although AZT had a beneficial effect on the surrogate markers of efficacy evaluated, these changes did not predict clinical outcome, nor could the markers be usefully incorporated into an endpoint definition.  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