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   2887篇
  免费   7篇
  国内免费   1篇
电工技术   13篇
化学工业   373篇
金属工艺   103篇
机械仪表   43篇
建筑科学   13篇
矿业工程   23篇
能源动力   18篇
轻工业   49篇
水利工程   9篇
石油天然气   108篇
无线电   44篇
一般工业技术   347篇
冶金工业   1693篇
原子能技术   44篇
自动化技术   15篇
  2022年   21篇
  2021年   26篇
  2019年   21篇
  2018年   33篇
  2017年   35篇
  2016年   50篇
  2015年   26篇
  2014年   33篇
  2013年   27篇
  2012年   47篇
  2011年   48篇
  2010年   35篇
  2009年   45篇
  2008年   31篇
  2007年   33篇
  2006年   48篇
  2005年   31篇
  2004年   21篇
  2003年   26篇
  2002年   18篇
  2001年   22篇
  1999年   36篇
  1998年   479篇
  1997年   285篇
  1996年   200篇
  1995年   153篇
  1994年   103篇
  1993年   96篇
  1992年   36篇
  1991年   33篇
  1990年   38篇
  1989年   27篇
  1988年   22篇
  1987年   25篇
  1986年   24篇
  1985年   28篇
  1984年   19篇
  1983年   20篇
  1982年   31篇
  1981年   26篇
  1980年   34篇
  1979年   23篇
  1978年   33篇
  1977年   87篇
  1976年   137篇
  1975年   24篇
  1974年   20篇
  1973年   22篇
  1972年   22篇
  1971年   19篇
排序方式: 共有2895条查询结果,搜索用时 15 毫秒
1.
2.
The present study aimed to investigate the effect of somatic cell count (SCC) of raw cow's milk on the volatile organic compound (VOC) profiles of yoghurt. Test yoghurt samples were produced from three batches of cow's milk with low, medium and high SCC, respectively. The VOCs were determined by gas chromatography–mass spectrometry (GC–MS) analysis. A lower diacetyl and acetoin content and a higher content of 2‐heptanone, and butanoic and hexanoic acids were established in the yoghurt samples from batches with high SCC of above 1 000 000 cells/cm3. The increased SCC of cow's milk had a negative effect on the volatile organic compound profiles of yoghurt.  相似文献   
3.
We characterize the meander of re-entrant excitation in a model of a sheet of mammalian ventricular tissue, and its control by resonant drift under feedback driven stimulation. The Oxsoft equations for excitability in a guinea pig single ventricular cell were incorporated in a two dimensional reaction-diffusion system to model homogeneous, isotropic tissue with a plane wave conduction velocity of 0.35 m s-1. Re-entrant spiral wave solutions have a spatially extended transient motion (linear core) that settles down into rotation with an irregular period of 100-110 ms around an irregular, multi-lobed spiky core. In anisotropic tissue this would appear as a linear conduction block. The typical velocity of drift of the spiral wave induced by low amplitude resonant forcing is 0.4 cm s-1.  相似文献   
4.
The report deals with the development of procedures, evaluation of laser application and prevention of complications involved in intensive chemoradiation therapy of neoplasms of hemopoietic and lymphoid tissue in childhood. The clinical data on 548 patients, aged 2 months-15 years, with leukemia and solid tumor were evaluated. Laser application for treatment of different complications of chemoradiation therapy of pediatric leukemia proved a valuable innovation. It had a pronounced antiinflammatory and analgetic effect, promoted tissue regeneration processes and cut down the duration of complication treatment drastically.  相似文献   
5.
6.
7.
8.
9.
We have established that technological defects (cracks) in zirconium articles can develop in the course of long-term storage prior to their mounting in a reactor, which is caused by the action of residual stresses and hydrogen. We have considered the conditions of after-operation storage of zirconium articles of the fuel core of thermal reactors in water of the cooling ponds of reactors and in spent-fuel storehouses. The possibility of subsequent hydrogenation of these articles during their storage has been shown. Finally, we have studied the effect of hydrogen, absorbed in the course of storage, on the crack resistance of zirconium articles and the development of defects in them due to delayed hydride cracking. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 5, pp. 105–109, September–October, 2007.  相似文献   
10.
Registered psychiatric morbidity in Bulgaria as a whole and particularly in Plovdiv, the second largest region of the country, was assessed. Three aspects of psychotropic drug usage were analysed, namely, changes in registered psychotropic drugs, the prescribed daily dose (PDD) values for 2 years, and the preferred therapeutic schemes, and drug usage and needs in a psychiatric hospital with 365 beds. This was done by time series analysis for evaluation of psychiatric morbidity and drug consumption data, calculation of PDD for psychotropic medicines, and, based on a modification of the World Health Organization's morbidity method, assessment and prediction of drug use and needs in Plovdiv hospital. The results indicated that the registered morbidity had increased by 4% over the period 1989-93 to 2,427 psychiatric patients per 100,000 people. The increased consumption of especially benzodiazepines and sedative medicines was analyzed. Diazepam was prescribed the most often (91.1%), followed by levomepromazine (86.4%), haloperidol (82.7%), etc. Future drug consumption in Plovdiv hospital is expected to decrease because therapeutic practice in hospitals has been revised and improved on the basis of the World Health Organization's recommendations.  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