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   45篇
  免费   2篇
化学工业   19篇
无线电   6篇
一般工业技术   8篇
冶金工业   13篇
自动化技术   1篇
  2023年   1篇
  2021年   1篇
  2018年   3篇
  2014年   1篇
  2011年   1篇
  2009年   2篇
  2008年   1篇
  2007年   3篇
  2005年   2篇
  2003年   1篇
  2002年   2篇
  2001年   3篇
  2000年   2篇
  1999年   1篇
  1998年   4篇
  1997年   4篇
  1996年   5篇
  1995年   2篇
  1994年   3篇
  1993年   1篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1986年   1篇
排序方式: 共有47条查询结果,搜索用时 15 毫秒
11.
The Rho GDP dissociation inhibitor (GDI) forms a complex with the GDP-bound form of the Rho family small G proteins and inhibits their activation. The GDP-bound form complexed with Rho GDI is not activated by the GDP/GTP exchange factor for the Rho family members, suggesting the presence of another factor necessary for this activation. We have reported that the Rho subfamily members regulate the ezrin/radixin/moesin (ERM)-CD44 system, implicated in reorganization of actin filaments. Here we report that Rho GDI directly interacts with ERM, initiating the activation of the Rho subfamily members by reducing the Rho GDI activity. These results suggest that ERM as well as Rho GDI and the Rho GDP/GTP exchange factor are involved in the activation of the Rho subfamily members, which then regulate reorganization of actin filaments through the ERM system.  相似文献   
12.
Numerical prediction of sound generated from flows with a low Mach number   总被引:3,自引:0,他引:3  
Numerical computations of sound generated from flows with a low Mach number are presented based on Lighthill’s acoustic analogy with an assumption that sound does not alter the flow field from which it is generated. The source fluctuations of the flow field are computed by a large-eddy simulation (LES) with Dynamic Smagorinsky Model (DSM) and they are fed to the following acoustical computation as input data. An explicit/implicit finite element method with second order accuracy both in time and space is used for flow field discretization. The method is applied to the prediction of sound in three different classes of problems: far-field sound generated from flow around a bluff body, sound resulting from blade-stator interaction of turbomachinery and sound due to a turbulent boundary layer on an aerofoil. The computed frequency spectra of the sound show a fairly good agreement with the measured spectra for all the cases.  相似文献   
13.
Hypelcin B is a mixture of antibiotic peptides produced by Hypocrea peltata. Hypelcins B-I, B-II, B-III, B-IV and B-V are components of this mixture purified by reversed-phase high-performance liquid chromatography. The amino acid sequences of these peptides were determined by electrospray mass spectrometry and electrospray mass spectrometry/mass spectrometry. The molecular weights of these peptides were all ca. 2000 and the structures were very similar.  相似文献   
14.
The dew and bubble points for the mixtures of dichlorodifluoromethane (CCl2F2; R 12) and bromotrifluoromethane (CBrF3; R13B1) were measured with the use of a constant-volume method coupled with an expansion procedure and visual observation of the meniscus at the vapor-liquid interface. In order to check the reliability of the apparatus used, vapor pressure measurements were conducted for carbon dioxide at 273.15 K and for two pure components, CCl2F2 and CBrF3. Thirty-eight dew and bubble points of the CCl2F2+CBrF3 system were determined for four different compositions of 0, 21, 45, and 70 mol % CBrF3 in the range of temperatures from 299 to 384 K, pressures up to 4.2 MPa, and densities from 89 to 1228 kg · m–1.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.  相似文献   
15.
Dizziness in childhood is not an infrequent symptom, but epileptic vertigo is a rare condition in children. Here we report an 8-year-old Japanese boy with epileptic vertiginous seizures. At age 8 years, he visited Nippon Medical School Hospital because of a ten day history of dizziness. The dizziness occurred more than twenty times a day and he was hospitalized. On physical examination, the patient appeared normal and there were no abnormal neurological findings, including eye movement and cerebellar signs. Ophthalmoscopy, otoscopy, vestibular function test and hearing test were normal. Computerized tomography scanning and MR imaging of the head revealed no significant abnormality. The dizziness observed on admission comprised sudden brief attacks of rotatory sensation without amnesia regarding the event. Sometimes the attacks were accompanied by tremor like movement and numbness of the right hand, followed by postictal unsteadiness. Interictal EEG revealed spike-and-wave complexes in the central region dominantly in the light sleep stage. On ictal EEG, seizure discharges were observed to begin in the left central region and they increased in amplitude and subsequently propagated to the frontal and occipital regions. These findings were most suggestive of partial seizures. The patient was treated with carbamazepine and the seizures became well under control.  相似文献   
16.
The formation of a plumbate network in binary lead silicate glasses was examined based on the leaching behavior of Pb2+ in lead silicate glasses over a wide composition region. The effective diffusion coefficient of Pb2+ at 40°C was on the order of 10−17 m2/s for PbO<35 mol% glasses, and increased three orders of magnitude for 35–50 mol% PbO contents. Such a steep composition dependence is considered to be because of changes in the medium or longer range structure. That is, it is proposed that the plumbate network forms a percolative 3D network in the composition region to form diffusion paths for the lead ions. In addition, the present results indicate that the lead ion exists as a network former over the entire glass forming composition range of the binary silicate glasses.  相似文献   
17.
In this study, room‐temperature mechanical rubbing is used to control the 3D orientation of small π‐conjugated molecular systems in solution‐processed polycrystalline thin films without using any alignment substrate. High absorption dichroic ratio and significant anisotropy in charge carrier mobilities (up to 130) measured in transistor configuration are obtained in rubbed organic films based on the ambipolar quinoidal quaterthiophene (QQT(CN)4). Moreover, a solvent vapor annealing treatment of the rubbed film is found to improve the optical and charge transport anisotropy due to an increased crystallinity. X‐ray diffraction and atomic force microscopy measurements demonstrate that rubbing does not only lead to an excellent 1D orientation of the QQT(CN)4 molecules over large areas but also modifies the orientation of the crystals, moving molecules from an edge‐on to a face‐on configuration. The reasons why a mechanical alignment technique can be used at room temperature for such a polycrystalline film are rationalized, by the plastic characteristics of the QQT(CN)4 layer and the role of the flexible alkyl side chains in the molecular packing. This nearly complete conversion from edge‐on to face‐on orientation by mechanical treatment in polycrystalline small‐molecule‐based thin films opens perspectives in terms of fundamental research and practical applications in organic optoelectronics.  相似文献   
18.
The structure of PbO–B2O3 glasses has been investigated in the composition range of 25–80 mol% PbO by using X-ray diffraction and 11B NMR techniques. The well-separated peaks due to Pb–O and Pb–Pb pairs were first observed in the radial distribution function, and peak deconvolution was performed by using a pair function method. The average coordination number of lead atoms was determined to be about 6 in the low-PbO-content region and about 3 in the high-PbO-content region. With an increase of PbO content, the peaks at 0.24 and 0.40 nm shifted to shorter distances, and especially the latter peak drastically increased in intensity in the composition range >50 mol% PbO. It was suggested that PbO is a main glass former in the high-PbO-content region. Based on the results obtained, we propose structural models of lead borate glasses.  相似文献   
19.
An open microstrip line with finite strip thickness is numerically analyzed by the Green's function technique. The normalized longitudinal current distributions are systematically obtained for the cases of various shape and thickness ratios in the quasi-TEM approximation. The obtained results are illustrated in figures for three surfaces of the thick strip conductor, that is, the lower, side, and upper surfaces. The closed-form expressions are obtained for the normalized longitudinal current distributions by taking a best fit to theoretical results  相似文献   
20.
To investigate the role of occupation as a risk factor for hairy cell leukaemia a case-control study on 121 male, hairy cell leukaemia (HCL) patients, and 484 controls matched for age and sex, was conducted. We found significantly elevated risk for HCL among building painters (OR, 5.7; 95% CI, 1.6-20.8; based on six cases and four controls) and construction workers (OR, 3.3; CI, 1.2-9.2; based on seven cases and eight controls). Farming has been suggested as a risk factor in HCL. In this investigation farmers had an OR of 1.2 (CI, 0.6-2.3) and farm workers an OR of 1.5 (CI, 0.8-2.8). However, having ever worked in farming yielded an OR of 1.8 (CI, 1.1-2.9). Having grown up mainly in a rural area gave an OR of 1.4 (CI, 0.9-2.4). UV light has been suggested as a risk factor for non-Hodgkin's lymphoma (NHL). To evaluate the impact of UV exposure, classification of occupations as indoor, outdoor or mixed indoor/outdoor was made. Outdoor and mixed outdoor/indoor work yielded ORs of 2.3 (1.0-4.9) and 1.6 (1.0-2.5), respectively. When the effect of outdoor/indoor or mixed indoor/outdoor work was analysed using a scoring system the OR was 2.0 (CI, 0.9-4.4) for farmers compared with 0.8 (CI, 0.3-1.9) among non-farmers in the highest scoring group. There was no clear correlation between socioeconomic status as defined by the Swedish Socio-Economic Classification (SEI), and the risk of HCL. As many comparisons were made, the possibility of associations occurring by chance can not be excluded.  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