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   1333篇
  免费   15篇
  国内免费   3篇
电工技术   7篇
综合类   1篇
化学工业   105篇
金属工艺   5篇
机械仪表   19篇
建筑科学   32篇
能源动力   10篇
轻工业   20篇
水利工程   2篇
石油天然气   6篇
无线电   83篇
一般工业技术   70篇
冶金工业   928篇
原子能技术   3篇
自动化技术   60篇
  2023年   3篇
  2022年   6篇
  2021年   6篇
  2020年   4篇
  2019年   11篇
  2018年   7篇
  2017年   2篇
  2016年   9篇
  2015年   6篇
  2014年   7篇
  2013年   26篇
  2012年   24篇
  2011年   25篇
  2010年   24篇
  2009年   25篇
  2008年   29篇
  2007年   31篇
  2006年   23篇
  2005年   18篇
  2004年   20篇
  2003年   17篇
  2002年   20篇
  2001年   17篇
  2000年   16篇
  1999年   36篇
  1998年   259篇
  1997年   160篇
  1996年   121篇
  1995年   56篇
  1994年   53篇
  1993年   66篇
  1992年   8篇
  1991年   11篇
  1990年   10篇
  1989年   19篇
  1988年   11篇
  1987年   18篇
  1986年   11篇
  1985年   17篇
  1983年   3篇
  1982年   5篇
  1981年   7篇
  1980年   12篇
  1978年   1篇
  1977年   25篇
  1976年   56篇
  1975年   3篇
  1971年   2篇
  1970年   1篇
  1955年   2篇
排序方式: 共有1351条查询结果,搜索用时 20 毫秒
11.
F.T.K. Au  Y.K. Cheung 《Thin》1996,24(1):19-51
The isoparametric spline finite strips for shells are employed to solve static and free vibration problems of variable-depth bridges of arbitrary alignments. Using this approach, a continuous bridge is first split up into substructures. Each substructure is modelled as an assemblage of isoparametric spline finite strips. Compatibility between substructures is ensured by suitable transformation at the interface. The presence of support diaphragms and bearings can also be accounted for. This method retains the computational efficiency of the spline finite strip method while it is much more flexible in geometric modelling. Solutions of this method are compared with other available solutions, and good agreement is observed.  相似文献   
12.
Appropriate scientific training demands the cooperation of the coach, player, doctor and physiotherapist. The training process involves the medical examination before a competitive season, the diagnosis and treatment of injuries when they occur, the prevention of injuries and the rehabilitation of the injured back into competitive play. It is in these respects that a coach requires the services of a doctor and/or a physiotherapist on the technical bench. This study therefore attempted to establish whether the soccer coaches were benefiting from the professional support of the doctors. The study sought the views of the Kenyan soccer coaches on the administration of first-aid and the preventive measures against injuries. Specifically, the study attempted to find out whether the Kenyan soccer clubs employed team doctors, whether the coaches had adequate knowledge in first-aid, the injury prevention measures that the coaches enforced, etc. A questionnaire was administered to 42 individual soccer coaches who were attending an advanced Confederation Africaine de Football (CAF) coaching course in Nairobi. Thirty-three (78.57%) were used in the study. The participants were drawn from all the provinces of Kenya except North Eastern. The findings were that 13 (39.4%) of the clubs represented did not have a qualified medical attendant; that in the absence of a team doctor, it is the coach who mostly administered first-aid (42.4%); that out of all the coaches only 15 (45.5%) were well versed in first-aid procedures, among others.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
13.
F.T.K. Au  Y.K. Cheung 《Thin》1996,24(1):53-82
The isoparametric spline finite strip method has been applied to the free vibration and stability analysis of shells. The convergence of the method is reviewed critically. Additional numerical examples on shells of different geometry are also employed to demonstrate the efficiency, accuracy and versatility of the method.  相似文献   
14.
15.
16.
17.
The Mono Mac 6 (MM6) human monocytic cell line was evaluated with the established J774 murine macrophage cell line to ascertain its effectiveness in determining the intracellular activities of antimycobacterial drugs. Cells were infected with Mycobacterium tuberculosis H37Ra and treated with drug concentrations corresponding to the MICs, as well as to threefold higher than and threefold less than the MICs. Changes in CFU were compared after 7 days to determine significant differences between treated and nontreated groups. The results suggest that MM6 will make a useful model for testing the intracellular activities of antituberculosis drugs.  相似文献   
18.
19.
An experiment was conducted to investigate the effects of immune responsiveness on excretion of oocysts after E. acervulina infection and subsequent effects on production characteristics of broilers (Gallus domesticus). These effects were determined in broilers repeatedly infected with 2.85 x 10(3) oocysts of E. acervulina and treated with various dosages of corticosterone in the diet (0, 10, 20 and 30 p.p.m.). Corticosterone treatment did not have an effect on the peak oocyst excretion, although it was administered from 4 days before initial infection. The number of oocysts excreted shortly after the peak and the length of the excretion period were increased in corticosterone-treated groups. The absence of a difference in peak oocyst excretion was ascribed to the existence of a time-lag between first contact with the parasite and rate of development of protective immunity. In a recently developed computer simulation model this period was assumed to be 5 days. Assuming that immunosuppression, through corticosterone, is only effective when protective immunity is in operation, the results indicate a time-lag of at least a few days, which supports the inclusion of such a time-lag in the computer simulation model. General immunosuppressive effects of the corticosterone treatment, monitored by antibodies and mitogen-induced lymphocyte stimulation confirmed that immunosuppression occurred shortly after medication started. Infection did not have a significant influence on production characteristics in animals without dietary corticosterone. However, with increasing corticosterone levels the negative effects of infection on production also increased.  相似文献   
20.
OBJECTIVE: To evaluate the use and efficacy of electroconvulsive therapy (ECT) in refractory major depression according to DSM-III-R criteria, and to look for factors predicting response in the acute phase and the occurrence of relapse or recurrence after recovery. DESIGN: Retrospective. SETTING: University Hospital Rotterdam, The Netherlands. METHODS: Of all patients who received ECT between January 1988 and July 1993 data were collected by study of clinical records and of information by treating physicians after discharge. Every patient was visited once, or received an outpatient department appointment, to obtain informed consent, take a follow-up history and evaluate social functioning by scoring Global Assessment of Functioning and Sickness Impact Profile rating scales. RESULTS: 35 patients received ECT. In clinical practice, the guidelines of the Netherlands Psychiatric Association were not violated; most patients had received adequate pharmacological pretreatment before the decision to start ECT was made. Two patients died in hospital (not from ECT). In the acute phase 25 of the 33 patients still alive upon discharge showed good recovery. Seven of these suffered relapse within six months. The number of patients with a return of depressive symptoms rose to 12 by the end of the first year of follow-up. Sociodemographic variables and treatment characteristics did not appear to influence the result of treatment in the acute phase, nor the occurrence of relapse or recurrence. With less intensive pre- and post-ECT drug treatment the chances of relapse were increased. CONCLUSIONS: ECT is an effective treatment in the acute phase of a depression. Results after a longer period of follow-up are less satisfactory.  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