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   1882篇
  免费   13篇
  国内免费   1篇
电工技术   2篇
化学工业   23篇
金属工艺   1篇
机械仪表   6篇
建筑科学   5篇
能源动力   4篇
轻工业   27篇
水利工程   2篇
石油天然气   1篇
无线电   3篇
一般工业技术   17篇
冶金工业   1793篇
自动化技术   12篇
  2023年   2篇
  2022年   3篇
  2021年   3篇
  2020年   4篇
  2018年   5篇
  2017年   5篇
  2016年   8篇
  2015年   8篇
  2014年   9篇
  2013年   7篇
  2012年   7篇
  2011年   10篇
  2010年   8篇
  2009年   5篇
  2008年   2篇
  2007年   5篇
  2005年   2篇
  2004年   2篇
  2003年   4篇
  2002年   1篇
  2001年   1篇
  2000年   3篇
  1999年   71篇
  1998年   614篇
  1997年   349篇
  1996年   209篇
  1995年   118篇
  1994年   72篇
  1993年   124篇
  1992年   11篇
  1991年   10篇
  1990年   13篇
  1989年   17篇
  1988年   11篇
  1987年   13篇
  1986年   9篇
  1985年   6篇
  1983年   4篇
  1982年   7篇
  1981年   10篇
  1980年   16篇
  1979年   1篇
  1978年   3篇
  1977年   27篇
  1976年   73篇
  1975年   3篇
  1954年   1篇
排序方式: 共有1896条查询结果,搜索用时 15 毫秒
1.
The authors report two cases of citrullinemia in siblings which add to 68 observations from the literature. They overview the clinical presentation, diagnosis and therapeutic management of the disease. The prognosis of severe neonatal form remains poor but an early adequate management may contribute to an acceptable outcome.  相似文献   
2.
3.
4.
Chitosan derivatives, sulfated N-acyl-chitosan (S-Cn-chitosan) possessing various lengths of alkyl chain, were prepared, and the properties of their aqueous solutions were examined. The 1H-NMR spectrum of D2O solutions of S-C12-chitosan showed broadening of the proton signals caused by aggregation of the alkyl chain. The solubility of a hydrophobic compounds, azobenzene, was small in the aqueous solutions of S-Cn-chitosan with shorter alkyl chains, but increased with increasing length of the chains above C10, showing that micelles had been formed. The ESR spectrum of a spin probe, TEMPO, in an S-C14-chitosan solution showed the existence of a hydrophobic region in the solution, but this region did not exist in the S-C2-chitosan solution. The rigidity of this region was examined by using a spin probe, 16-doxyl-stearic acid. From these results, it was revealed that S-Cn-chitosan with longer alkyl chains formed a novel type of micelle called a "polymer micelle," which was more stable than the ordinary micelles formed from low-molecular-weight surfactants.  相似文献   
5.
Duchenne muscular dystrophy (DMD) is a muscle disease characterized by the absence of the protein dystrophin, which causes a loss of sarcolemma integrity, determining recurrent muscle injuries, decrease in muscle function, and progressive degeneration. Currently, there is a need for therapeutic treatments to improve the quality of life of DMD patients. Here, we investigated the effects of a low-intensity aerobic training (37 sessions) on satellite cells, peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1α protein (PGC-1α), and different types of fibers of the psoas muscle from mdx mice (DMD experimental model). Wildtype and mdx mice were randomly divided into sedentary and trained groups (n = 24). Trained animals were subjected to 37 sessions of low-intensity running on a motorized treadmill. Subsequently, the psoas muscle was excised and analyzed by immunofluorescence for dystrophin, satellite cells, myosin heavy chain (MHC), and PGC-1α content. The minimal Feret’s diameters of the fibers were measured, and light microscopy was applied to observe general morphological features of the muscles. The training (37 sessions) improved morphological features in muscles from mdx mice and caused an increase in the number of quiescent/activated satellite cells. It also increased the content of PGC-1α in the mdx group. We concluded that low-intensity aerobic exercise (37 sessions) was able to reverse deleterious changes determined by DMD.  相似文献   
6.
7.
Edible coatings based on sodium alginate (AL) and pectin (PE) at 1% and 2%(w/v) enriched with eugenol (Eug) and citral (Cit) at minimum inhibitory concentrations (MIC) (0.10% and 0.15%) and double MIC were used to preserve the quality of fresh‐cut apples ‘Bravo de Esmolfe’. Samples were taken, through 14 day at 4 °C, for analysis of colour CIE(L*h°C*), firmness, °Brix, weight loss, antioxidant activity (TEAC), microbial growth and taste panels. With those quality characteristics, three groups were formed by the principal component and hierarchical cluster analysis, for each coating base (AL or PE). Based on, for each quality parameter measured, the mean closest value to the one at harvest for colour, higher value for firmness, °Brix and TEAC, and lower value for weight loss and microbial spoilage, the best group was selected for AL and PE. From each group, two edible coatings with the highest scores in overall acceptability were selected for fresh‐cut apples: AL2% + Eug 0.1%, AL2% + Cit 0.15% + Eug 0.1%, PE 2% + Cit 0.15% and PE 2% + Eug 0.2%.  相似文献   
8.
1. The rat hypothalamus (containing the supra-optic nuclei, paraventricular nuclei, median eminence and proximal pituitary stalk) has been incubated in vitro and shown to be capable of releasing the neurohypophysial hormones, oxytocin and arginine vasopressin, at a steady basal rate about one twentieth that of the rat neural lobe superfused in vitro. 2. The hypothalamus and neural lobe in vitro released both hormones in a similar arginine vasopressin/oxytocin ratio of about 1-2:1. However, when release was expressed relative to tissue hormone content, the hypothalamus was shown to release about three times as much arginine vasopressin and six times as much oxytocin as the neural lobe. 3. Dopamine in a concentration range of 10(-3)-10(-9)M caused graded increases in hormone release from the hypothalamus in vitro to a maximum fivefold increase over preceding basal levels. The demonstration that apomorphine also stimulated hormone release whereas noradrenaline was relatively ineffective suggested that a specific dopamine receptor was involved. A separate cholinergic component in the release process was indicated by the finding that acetylcholine stimulated release to a maximum fivefold increase in concentrations of 10(-3)-10(-9)M. 4. The fact that the isolated hypothalamus can be stimulated by dopamine and acetylcholine to release increased amount of oxytocin and arginine vasopressin raises the question of the origin and fate of the hormones released in this way. The possibility that they could be released into the hypophysial portal circulation from median eminence to affect the anterior lobe of the pituitary is discussed. 5. In similar doses, both dopamine and noradrenaline injected into the lateral cerebral ventricles of the brain of the anaesthetized, hydrated, lactating rat caused the release of arginine vasopressin and oxytocin. Apomorphine release both hormones but at a higher dose level and to less effect than the catecholamines. 6. The hormone release induced in vivo by dopamine could be prevented by the prior administration of haloperidol or phentolamine and these antagonists were equally effective in blocking the hormone release due to noradrenaline. The involvement of a specific dopamine receptor was more clearly implicated by the use of pimozide which completely inhibited the hormone release due to dopamine and apomorphine but not that due to noradrenaline. 7. It is suggested that the release of neurohypophysial hormones can be stimulated via a dopaminergic nervous pathway in addition to a cholinergic one. The possibility that the osmoreceptor mechanism for the release of antidiuretic hormone from the neural lobe of the pituitary may involve such a dopaminergic pathway is discussed.  相似文献   
9.
Side-effects of high pressure irrigation   总被引:1,自引:0,他引:1  
This study was undertaken to identify side-effects of high pressure irrigation. Standardized surgical wounds made in Yorkshire pigs were subjected to high pressure syringe and pulsatile irrigation. As a result of these treatments, fluids were disseminated into the adjacent tissue of the wound, predominantly in a lateral direction. Bacteria did not accompany this disseminated fluid and apparently were filtered out by the surface tissues. This treatment results in a tissue injury which impairs its defenses, making the wound more susceptible to infection. However, the remarkable cleansing capacity of high pressure irrigation appears to outweigh this side-effect, since heavily contaminated wounds subjected to this treatment heal per primum without infection.  相似文献   
10.
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