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   50篇
  免费   2篇
电工技术   3篇
化学工业   17篇
建筑科学   3篇
能源动力   2篇
无线电   4篇
一般工业技术   5篇
冶金工业   12篇
原子能技术   5篇
自动化技术   1篇
  2018年   1篇
  2016年   1篇
  2015年   1篇
  2014年   1篇
  2013年   2篇
  2012年   1篇
  2011年   2篇
  2010年   1篇
  2007年   1篇
  2006年   1篇
  2005年   2篇
  2004年   1篇
  2003年   2篇
  2002年   1篇
  2001年   1篇
  2000年   3篇
  1999年   2篇
  1998年   9篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1993年   2篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1982年   1篇
  1979年   1篇
  1977年   1篇
  1976年   1篇
排序方式: 共有52条查询结果,搜索用时 31 毫秒
1.
Suspension cultures of tobacco cells were studied using airlift and rotary-drum bioreactors. The effect of initial concentrations of a major substrate, sucrose, on the growth and production of a secondary metabolite, phenolic compounds, was investigated. The dry weights and total concentrations of the phenolic compounds increased with the initial sucrose concentration in both bioreactors. Both bioreactors were found to have the same tendency for the effect of initial sucrose concentration. The structured model, presented previously was modified by considering that sucrose was hydrolyzed to glucose and fructose by an enzymatic reaction. The previous and the new models were applied to the above two sets of experimental data obtained with two bioreactors, independently. The hydrolysis of sucrose was elucidated to contribute slightly to the overall kinetics of growth and secondary metabolite production in these cultures. Furthermore, the levels of shear damage in each bioreactor were quantitatively compared based on the death rate constant, ki, which is one of the model constants.  相似文献   
2.
The purpose of pipe rupture studies in JAERI is to perform model tests on pipe whip, restraint behavior, jet impingement and jet thrust force, and to establish a computational method for analyzing these phenomena. This report presents the analytical results of 4-inch pipe whip tests under BWR LOCA conditions.Dynamic response analyses were performed using the general-purpose finite element program ADINA. The test pipe was modelled by straight beam elements and the four restraints were modelled by a single truss element. The analytical results were compared with the experimental results. Impact time and maximum total restraint force showed good agreement with experimental results. On the other hand, pipe strain and pipe deflection could not be predicted so well. The reason for this is that the sliding of the restraint during the pipe whip movement cannot be considered in the analyses.  相似文献   
3.
The suppression of apoptosis may contribute to the carcinogenicity of the peroxisome proliferators (PPs), a class of non-genotoxic rodent hepatocarcinogens. Our previous work demonstrated that the PP nafenopin suppressed both spontaneous and transforming growth factor beta1 (TGFbeta1)-induced hepatocyte apoptosis both in vivo and in vitro. Here, we extend these observations by demonstrating the ability of nafenopin to suppress apoptosis induced by other major candidates for the signalling of cell death in the liver. Treatment of rat or mouse hepatocyte monolayers with TGFbeta1 or the DNA damaging drugs etoposide or hydroxyurea induced high levels of apoptosis. Western blot analysis did not support a role for either p53 or p21waf1 in etoposide-induced apoptosis in rat hepatocytes. Treatment of mouse hepatocytes with an agonistic anti-Fas antibody also resulted in an induction of high levels of apoptosis. Pre-addition and continued exposure to nafenopin suppressed apoptosis induced by all three stimuli. Overall, our studies demonstrate that the ability of nafenopin to protect hepatocytes from apoptosis is not restricted to species or apoptotic stimulus. It is possible, therefore, that the PPs may suppress apoptosis by acting on diverse signalling pathways. However, it seems more likely that nafenopin suppresses hepatocyte apoptosis elicited by each death stimulus by impinging on a core apoptotic mechanism.  相似文献   
4.
An ionic-polymer–metal-composite film shows electro-mechanical coupling. When the film is bent, electric current is induced. Measurement of the induced current indicates that the current depends on the speed of bending, but the total amount of the charge transferred across the film is independent of the speed, and depends only on the magnitude of the bending. The result indicates that in addition to previously proposed dynamical coupling effect, there is a static electro-mechanical coupling effect. Mathematical model is proposed to describe this phenomena.  相似文献   
5.
6.
This paper reports on a new technique of measurements of microbubble position in three dimensions with high time-resolution. The technique is based on micro digital holographic particle tracking velocimetry. In this technique, an intensity profile is constructed from a holographic image of a microbubble where the profile results in showing two peaks. The distance between the two peaks appears to relate to the size of the microbubble's diameter. The three-dimensional position of the bubble can be detected by the center of the two peaks and the center point of the bubble image focused by a digital hologram. We also theoretically obtained the intensity profile of a microbubble by considering a refraction of light on a bubble surface to a ring-shaped aperture model. The theoretically obtained distance between the two peaks is found to be in good agreement with the values obtained experimentally.  相似文献   
7.
The activity of 5- to 6-year-old Japanese children (n = 29) was monitored for 3 consecutive days, including one weekend day, using an ActivTracer tri-axial accelerometer. The daily inhalation rate and time spent in sedentary, light, or moderate to vigorous levels of physical activity (MVPA) were estimated from the accelerometer measurements based on previously developed regression equations. The 3-day mean daily inhalation rate (STPD) was estimated at 8.3 ± 1.4 m3 day−1 in 10 subjects who completed 3 days of monitoring. The time spent in sedentary, light, or MVPA each day was 320, 415, and 81 min day−1, respectively. Analysis of between-day reliability indicated that 3 days of monitoring with the ActivTracer tri-axial accelerometer provided an acceptable estimate of daily inhalation rate (intra-class correlation coefficient [ICC] = 0.892), but low to moderate reliability for the time spent in different levels of activities (ICC = 0.43 to 0.58). We observed a significant difference in the daily inhalation rate between weekdays and the weekend day, possibly due to differences in time spent in MVPA. This finding suggests that a weekend day should be included to obtain more reliable estimates of daily inhalation rate using an accelerometer.  相似文献   
8.
The relationship between peripheral lymphocyte apoptosis and human immunodeficiency virus disease progression was studied in infected subgroups with distinct profiles of progression. Long-term nonprogressors (LTNP) and seronegative controls had levels of spontaneous apoptosis significantly lower than those for recent seroconverters who had CD4 cell counts similar to those of nonprogressors but with a high likelihood of disease progression. Lymphocytes from nonprogressors and seronegative controls also showed negligible spontaneous caspase-3 activity, a biochemical indicator for apoptosis, whereas early progressors exhibited substantial activity. In contrast, when activated with mitogens, the lymphocytes from both LTNP and progressors displayed indistinguishable levels of heightened apoptosis. Spontaneous apoptosis and plasma viremia levels correlated positively in progressors, but not in LTNP. These findings demonstrate that increased lymphocyte apoptosis is evident prior to CD4 T cell decline and that LTNP are relatively resistant to the factors that induce accentuated levels of spontaneous but not mitogen-induced cell death.  相似文献   
9.
10.
Prognosis of osteosarcoma has been improved markedly with the introduction of effective, intensive chemotherapy. However, there are many reports that indicate that the prognosis of osteosarcoma with pulmonary metastases at the initial presentation is poor. One hundred seventeen patients with osteosarcoma involving the extremities were treated at the Chiba Cancer Center from 1976 to 1995. Of these, nine (7.6%) patients had pulmonary metastases at initial presentation; these nine patients are the subjects of this article. There was an average of 0.9 pulmonary metastatic lesions at initial presentation seen on plain chest radiographs, an average 2.9 lesions seen on computed tomograms of the chest, and an average 12.7 lesions found at thoracotomy in these nine patients. The pulmonary metastatic lesions that could not be detected by computed tomography of the chest were resected by thoracotomy. Three patients died, and six patients are alive, with the 5-year survival being 64.8%. Intensive chemotherapy and aggressive surgical therapy were done for these patients with osteosarcoma with pulmonary metastases at initial presentation, and it is thought that this improved the prognosis of these patients. Pulmonary metastases of osteosarcoma at initial presentation do not always indicate a hopeless prognosis.  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