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   3909篇
  免费   2篇
化学工业   20篇
金属工艺   2篇
建筑科学   1篇
能源动力   1篇
轻工业   3篇
石油天然气   2篇
无线电   1篇
一般工业技术   3篇
冶金工业   3869篇
原子能技术   1篇
自动化技术   8篇
  2020年   1篇
  2018年   1篇
  2015年   1篇
  2014年   3篇
  2013年   1篇
  2011年   1篇
  2010年   1篇
  2008年   1篇
  2007年   1篇
  2006年   2篇
  2005年   2篇
  2004年   1篇
  2003年   7篇
  2002年   1篇
  2001年   2篇
  2000年   3篇
  1999年   108篇
  1998年   1155篇
  1997年   702篇
  1996年   451篇
  1995年   219篇
  1994年   224篇
  1993年   212篇
  1992年   17篇
  1991年   44篇
  1990年   37篇
  1989年   45篇
  1988年   33篇
  1987年   42篇
  1986年   52篇
  1985年   34篇
  1984年   1篇
  1983年   14篇
  1982年   17篇
  1981年   25篇
  1980年   50篇
  1979年   3篇
  1978年   9篇
  1977年   111篇
  1976年   259篇
  1975年   7篇
  1973年   1篇
  1964年   1篇
  1961年   1篇
  1957年   1篇
  1955年   5篇
  1954年   2篇
排序方式: 共有3911条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
The clinical and pathological findings of a 43-year-old woman, diagnosed as having acute hemorrhagic leukoencephalitis at postmortem examination, are presented. The acute hemorrhagic leukoencephalitis affects mainly young adults and is the most fulminant from of demyelinating disease. It is frequently preceded by a respiratory infection. Diagnosis is facilitated by CT scanning and MRI, which reveal the massive lesion in the cerebral white matter. Many cases terminate fatally in 2 or 4 days, but in others survival is longer. The pathological findings are distinctive.  相似文献   
5.
6.
7.
Well-differentiated thyroid cancer (i.e. papillary microcarcinoma) may be revealed by a clinically palpable cervical node, especially in young patients. Primary tumor specificity (small-sized, superior location, invasion, multifocality) and characteristics of cervical node involvement (with synchronous central and lateral multiple node spread) require appropriate treatment by a skilled surgeon. Contrary to the primary tumor treatment (total thyroidectomy), surgical management of the cervical node basins remains controversial. Only a special knowledge of the specificity of this disease and cervical lymphatic anatomy will ensure a good prognosis for the patient.  相似文献   
8.
The dynamic mechanical behaviour of solid wood, fibreboard, and wood laminates has been examined in the temperature range –100 to +150° C. Two events are apparent in the response of the solid wood, a low-temperature (–50° C) transition which is interpreted as being associated with the onset of movement of bound water, and a higher temperature (40 to 120° C) thermal softening process. With fibreboard, the relationship between the shear storage modulus and density is shown to be described by a simple packing efficiency factor applicable over a wide range of temperature. The behaviour of the laminates is strongly dependent upon the orientation of the outer ply. A model is proposed which analyses the response of the laminate in terms of its constituent plies and allows calculation of numerical values of the component shear storage moduli. With both the fibreboard and the laminates the binder, urea-formaldehyde resin, is shown to have a significant influence on the absolute values of tan observed.  相似文献   
9.
To test a potential "gating" effect of noradrenaline (NA) in the auditory cortex, the acoustic threshold was estimated by determining the rate-level function of neurons before, during, and after microiontophoretic application (5-40 nA) of NA. The rationale behind this experiment was that a gating effect should decrease the threshold for acoustic excitatory responses. From 84 recorded neurons, we observed (1) that application of NA increased the threshold for 48 of 84 cells, and (2) that, on average, the slope of the rate-level functions was unchanged. These effects on the threshold are consistent with the fact that the dominant effect of NA on the evoked response is inhibition for 34 of 84 cells; increases in evoked responses were observed for only 14 of 84 cells. GABA application (0-50 nA) also led to increased response threshold for 19 of 24 cells (unaffected, 5 of 24 cells). However, for three cells the effect of GABA application was antagonized by bicuculline application, while on the same cells bicuculline application did not prevent the noradrenergic increase in threshold. The effect induced by NA on the threshold raises questions about the generality of a gating effect of NA in sensory neocortex.  相似文献   
10.
War is a complex social situation due to the interplay of multiple factors. Economical and political ones are of utmost importance, but human attitudes and motivations must be also taken into account. Being desirable to modify human transactions in such a way that they do not interfere with the basic right of everyone to a condition of physical and mental well-being, war must be abolished. The author contends that an understanding of behaviour through Psychology can be helpful in that aim. Aggression is considered the principal psychological cause of war. It is worth while to differentiate between aggression as an instrument for attaining a special end, and as pure hostility. Only in the first form, it is held here, does it play an important role in war. Psychogists must deal also with a wide range of states of mind that can be "served" by aggression: feelings of inferiority or insecurity, fear, greed, projections, compensations, rationalizations, etc. Scientific approach is not the only one Physiology brings to war prevention. It is equally important the wide dissemination of its conclusions among the general public. Information on the dynamics that prompt people to decide war would make it easier to control. This applies not only to political or military leaders, but also to civil populations. Concerning those two possible contributions of psychologists, scientific and educative, it is suggested the extensive use of psychodramatic techniques. Their richness lie in the lifelike experiences they convey to the participants, and particular aptitude to promote changes of attitudes. Investigation and information on the psychological processes related to war should be undertaken by international organizations of social scientists, acting simultaneously in several countries. Some of the initial steps they could further: 1) that prevention of war be a current subject matter in psychological courses; 2) that the World Health Organization take interest in this subject; 3) that psychologists participate in international political and economical bodies in order to clarify the psychological factors leading to war.  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