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   305篇
  免费   6篇
  国内免费   5篇
电工技术   4篇
综合类   14篇
化学工业   9篇
金属工艺   6篇
机械仪表   2篇
建筑科学   10篇
能源动力   1篇
轻工业   22篇
水利工程   6篇
武器工业   1篇
无线电   8篇
一般工业技术   12篇
冶金工业   200篇
自动化技术   21篇
  2018年   2篇
  2015年   2篇
  2014年   4篇
  2013年   20篇
  2012年   8篇
  2011年   4篇
  2010年   4篇
  2009年   12篇
  2008年   5篇
  2007年   3篇
  2006年   7篇
  2005年   4篇
  2004年   8篇
  2003年   1篇
  2002年   5篇
  2001年   2篇
  2000年   5篇
  1999年   9篇
  1998年   63篇
  1997年   37篇
  1996年   31篇
  1995年   11篇
  1994年   14篇
  1993年   12篇
  1992年   1篇
  1991年   2篇
  1990年   3篇
  1989年   4篇
  1988年   2篇
  1986年   1篇
  1984年   1篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1978年   2篇
  1977年   6篇
  1976年   12篇
  1955年   1篇
  1946年   1篇
  1945年   2篇
排序方式: 共有316条查询结果,搜索用时 0 毫秒
1.
Visual and auditory stimulus discrimination tasks, analogous to those used in the Reitan-Klove Sensory Perceptual Examination, were performed by 12 cocaine-dependent and 5 alcohol-dependent patients after 1 week, 3 weeks, and 3 months of verified abstinence. Sixteen control subjects, who were not substance-dependent, performed the same tasks after comparable intervals. During each task, either visual or auditory stimuli were presented in the left, in the right, or in both sensory fields. A simple key press was made to discriminate these conditions. Cocaine-dependent patients responded more slowly than control subjects during both tasks. The reaction-time slowing persisted across all three sessions, spanning a 3-month period of abstinence. There were no significant differences between the cocaine-dependent and control groups in response accuracy. In the context of other findings, these findings are interpreted as reflecting an enduring effect of prior cocaine dependence on motor as opposed to sensory functioning.  相似文献   
2.
Cytophotometry of rat blood erythroid cells during anaemia, induced by phenylhydrazin (4-8 days from the beginning of injections), revealed that all forms of bone marrow containing haemoglobin were thrown into the blood. On its peak (4th day), the greatest contribution in blood haemoglobinization (50%) is made by microcytes. From the 5th day and up to the end of the restoration period the important role in this process is played by macrocytes. From the 6th day the role of normocytes increases, whose contribution by 8th day reaches 70% of the whole haemoglobin amount in blood. In contrary to anaemizated birds, whose erythroid cells ripen in blood, in rats all the transformations of erythron during anaemia are accomplished in bone marrow.  相似文献   
3.
本文针对网络学堂如何辅助高等数学课堂教学进行了研究,介绍了建设高等数学网络学堂的必要性,提出了建设高等数学网络学堂的途径,最后探讨了如何利用网络学堂提高高等数学教学质量。  相似文献   
4.
PURPOSE: To develop and evaluate a simple, yet well defined, method to measure diffusion in semi-solids, i.e. polymeric materials. METHODS: The method was based on a concept where equivalent discs of polymeric films were cut and stacked on top of each other. The diffusion process was allowed to proceed unidimensionally through the stack of films perpendicular to the film surface. After an appropriate time, the stack was analysed disc by disc with respect to solute content and from the concentration profile so obtained the diffusion coefficient was calculated. RESULTS: An all-in-one device was developed, manufactured in stainless-steel, that cuts circular discs and stores each one successively in a "stack" in the cell compartment. CONCLUSIONS: Data from a silicone based system shows that the method, although simple, is accurate and reproducible.  相似文献   
5.
Thromboelastography (TEG) has been used after cardiopulmonary bypass (CPB) to diagnose excessive postoperative hemorrhage. Conventional TEG during CPB is not possible due to the sensitivity of the TEG to even small amounts of heparin, which produces a nondiagnostic tracing. The purpose of this study was to compare heparin neutralization using heparinase or protamine in TEG blood samples obtained during CPB. TEG testing was performed on 48 patients before, during and after CPB. Tissue plasminogen activator activity and antigen were measured on a subset of 32 patients. We found: 1) heparinase neutralized at least 10 IU/ml heparin while 1.6 ug/ml protamine neutralized up to 7 IU/ml heparin, 2) in samples with complete heparin neutralization by both methods, there was no significant difference in the R values, 3) while there was good correlation for other TEG parameters between heparinase and protamine treated samples, heparinase treatment produced shorter K values and higher angle, MA and A60, 4) while fibrinolysis was detected using both methods, heparinase treatment suppressed fibrinolysis in the TEG in both samples from patients and after in vitro addition of tissue plasminogen activator, 5) TEG was not a sensitive indicator of t-PA activity, detecting only 21% of samples with increased t-PA activity during bypass, and 5) heparinase was at least 100 times more expensive than protamine. We conclude that while both heparinase and protamine can be used to neutralize heparin in TEG samples obtained during CPB, protamine neutralization is more sensitive to fibrinolysis and less expensive, but the protamine dose must be carefully selected to match the heparin level used at individual institutions.  相似文献   
6.
采用电液比例控制技术对电解铜堆垛装置进行控制。分析了控制的工作原理及实现方法;探讨了系统的稳定性;采用PID校正技术对系统的稳定性进行校正。  相似文献   
7.
在高水头水电站明岔管设计中 ,由于岔管的钢管壁较厚 ,给岔管的制作带来很大的困难。为此在大七孔电站钢岔管设计时 ,借鉴国内的钢衬钢筋混凝土管技术的经验 ,采用了钢衬钢筋混凝土岔管。解决了高水头岔管的设计及施工难题  相似文献   
8.
三级配混凝土输送泵在鱼塘水电站混凝土施工中的应用   总被引:1,自引:0,他引:1  
鱼塘水电站溢洪道混凝土共计14.9万m3,由于受不良地质和洪水冲毁围堰等因素影响致使开挖结束时工期严重滞后,而整个电站安全度汛又迫在眉睫,故必须寻求加快溢洪道混凝土浇筑速度的办法。为此,采用国内首批HBT120A三级配混凝土输送泵作为混凝土主要的入仓手段,使施工进度明显加快,弥补了原已滞后的工期,保证了鱼塘水电站溢洪道工程安全度汛目标的实现,并为2005年9月底水库下闸蓄水目标的实现奠定了坚实的基础。本文主要介绍HBT120A三级配混凝土输送泵在该工程施工中的应用。  相似文献   
9.
Trace contaminants in water, including metals and organics, often are measured at sufficiently low concentrations to be reported only as values below the instrument detection limit. Interpretation of these “less thans” is complicated when multiple detection limits occur. Statistical methods for multiply censored, or multiple-detection limit, datasets have been developed for medical and industrial statistics, and can be employed to estimate summary statistics or model the distributions of trace-level environmental data.We describe S-language-based software tools that perform robust linear regression on order statistics (ROS). The ROS method has been evaluated as one of the most reliable procedures for developing summary statistics of multiply censored data. It is applicable to any dataset that has 0 to 80% of its values censored. These tools are a part of a software library, or add-on package, for the R environment for statistical computing. This library can be used to generate ROS models and associated summary statistics, plot modeled distributions, and predict exceedance probabilities of water-quality standards.  相似文献   
10.
The clinical course was studied as was the condition of cardiohemodynamics in 126 patients with different variants of diphtherial myocarditis (DM) versus 23 patients with unspecific infectious and allergic myocarditis (UIAM). Early DM in the majority of cases runs a moderately severe or severe course because of a stronger--by comparison with late DM and UIAM--predisposition to cardiac insufficiency, sinus bradycardia and heart blocks as well as of a moderately severe systolic dysfunction of the left ventricle (LV), as evidenced by Echo-CG. Late DM runs, on the whole, a mild course, and is associated with minimal LV systolic function inadequacies.  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