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   1155篇
  免费   29篇
  国内免费   1篇
电工技术   4篇
综合类   2篇
化学工业   99篇
金属工艺   16篇
机械仪表   35篇
建筑科学   4篇
矿业工程   2篇
能源动力   13篇
轻工业   25篇
水利工程   1篇
石油天然气   1篇
无线电   107篇
一般工业技术   82篇
冶金工业   740篇
原子能技术   7篇
自动化技术   47篇
  2023年   6篇
  2022年   5篇
  2021年   8篇
  2020年   9篇
  2019年   10篇
  2018年   17篇
  2017年   6篇
  2016年   23篇
  2015年   14篇
  2014年   17篇
  2013年   20篇
  2012年   27篇
  2011年   39篇
  2010年   19篇
  2009年   28篇
  2008年   24篇
  2007年   23篇
  2006年   20篇
  2005年   14篇
  2004年   15篇
  2003年   16篇
  2002年   13篇
  2001年   14篇
  2000年   10篇
  1999年   36篇
  1998年   223篇
  1997年   125篇
  1996年   75篇
  1995年   37篇
  1994年   49篇
  1993年   35篇
  1992年   9篇
  1991年   11篇
  1990年   8篇
  1989年   14篇
  1988年   15篇
  1987年   6篇
  1986年   4篇
  1985年   3篇
  1983年   6篇
  1982年   2篇
  1981年   6篇
  1980年   16篇
  1979年   2篇
  1978年   5篇
  1977年   29篇
  1976年   67篇
  1975年   2篇
  1966年   1篇
  1955年   1篇
排序方式: 共有1185条查询结果,搜索用时 62 毫秒
121.
122.
In this investigation, the presence of NKA-immunoreactive substances was determined in pineal glands from intact, castrated and castrated, testosterone-treated male rats. The effect of environmental light, melatonin treatment and superior cervical ganglionectomy on pineal NKA-immunoreactive substances was also investigated. The results obtained show that NKA is present in measurable amounts in the rat pineal, and NPK is probably also present, Orchidectomy was followed by an increase in the content of NKA-immunoreactive substances in the pineal gland. The replacement treatment with testosterone propionate in castrated rats blocked this effect. NKA-immunoreactive substances were not significantly different quantitatively in pineals from rats killed under light or under darkness. The removal of the superior cervical ganglia was followed by a significant increase in the NKA-immunoreactive substance content in the pineal gland of male rats. These results indicate that NKA and other tachykinins are present in the pineal gland of the male rat, and they seem to be regulated by gonadal hormones and the innervation originated from the superior cervical ganglia.  相似文献   
123.
11 cases of rapid central death following combination of sublethal doses of alcohol and sedativa are presented with case-history, histology, alcohol-concentrations and toxicological findings.  相似文献   
124.
The role of the sinoatrial ring bundle (SARB) in internodal conduction was examined by the microelectrode technique in excised rabbit hearts. The spread of the sinus impluse to the surrounding tissues was shown to proceed anteriorly toward the right branch of the crista terminalis significantly faster than toward the other direction. Thus the right SARB and the right branch of the crista terminalis close to the sinus node were the earliest areas excited by the sinus impulse in the areas surrounding the sinus node. It was further shown that the activation sequence does not initiate from the right SARB to the right branch of the crista terminalis via the junction of these two structures. Cutting the SARB did not produce any delay in conduction from the sinus node to the atrioventricular (AV) node. The conduction velocity measured at the endocardial surface by two microelectrodes has proved that conduction in the crista terminalis was significantly faster than in the SARB. The upstroke of the action potential from the crista terminalis was also steeper than that from the SARB. These results suggest that the SARB is not the main route for impulse propagation from the sinus node to the AV node; the fastest internodal conduction therefore takes place with wide wave fronts, along the crista terminalis.  相似文献   
125.
Bone fragility and increased fat content in the liver of egg-laying hens are more often encountered in birds from traditional battery-cage systems than in those confined in other systems. By reviewing the relevant literature possible explanations of these phenomena are proposed. Clinical and pathological manifestations of the syndromes are described and a number of possible aetiological factors are evaluated. Bone fragility can be seen either as a general weakness of bone tissue or as a clinically manifest disease, Cage layer fatigue. It is concluded, that general restriction of the animal's possibilities to locomote and perform comfort movements are the most important aetiological factors. Fatty liver disease may be seen either as a pathological elevation of the liverfat content or it may be seen as a disease called Fatty liver haemorrhagic syndrome. Several factors may cause elevation of the liver fat content. The influence of restricted movement on the animals energy balance, however, like other behavioural disturbances seems to be the most important aetiological factors. It is concluded, that bone fragility and fatty liver in egg-laying hens are diseases caused by an inadequate environment and the restriction of essential behavioural patterns.  相似文献   
126.
127.
A retention model for ionizable compounds in micellar liquid chromatography is derived and verified. The use of the model for the prediction of retention is illustrated and appropriate optimization strategies for the separation of ionizable compounds in Micellar Liquid Chromatography are discussed.  相似文献   
128.
129.
130.
We injected i.c.v. the natural agonist alpha-MSH (melanocyte-stimulating hormone) and the first selective melanocortin MC4 receptor antagonist HS014 (cyclic [AcCys11, D-Nal14, Cys18, Asp-NH(2)22]-beta-MSH(11-22) in rats and scored a number of behavioral effects which have been related to the melanocortic peptides. The results showed that HS014 (5 microg/rat) completely blocked alpha-MSH (3 and 5 microg/rat)-induced grooming, yawning and stretching. Penile erections induced by alpha-MSH were, however, only partially blocked by HS014. Injections of alpha-MSH decreased food intake in food-deprived rats, whereas HS014 increased food intake. When the peptides were given together, the food intake was similar to that of saline treated controls. Locomotion/exploration and resting were not influenced by either peptide. Our data show that exogenous beta-MSH decreases food intake, and that an endogenous central melanocortinergic inhibitory tone on feeding prevails which can be blocked with HS014, leading to an increase in food intake. Our data also provide evidence that grooming, stretching and yawning in rats may be mediated by the melanocortin MC4 receptor, whereas penile erections might perhaps be mediated by some other melanocortin receptor.  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