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   298篇
  免费   17篇
电工技术   3篇
综合类   1篇
化学工业   113篇
金属工艺   1篇
机械仪表   10篇
建筑科学   9篇
能源动力   6篇
轻工业   82篇
水利工程   1篇
石油天然气   1篇
无线电   9篇
一般工业技术   29篇
冶金工业   5篇
原子能技术   1篇
自动化技术   44篇
  2024年   1篇
  2023年   1篇
  2022年   37篇
  2021年   33篇
  2020年   13篇
  2019年   5篇
  2018年   3篇
  2017年   14篇
  2016年   13篇
  2015年   8篇
  2014年   12篇
  2013年   27篇
  2012年   22篇
  2011年   22篇
  2010年   12篇
  2009年   9篇
  2008年   14篇
  2007年   5篇
  2006年   1篇
  2005年   5篇
  2004年   3篇
  2003年   4篇
  2002年   4篇
  2000年   4篇
  1999年   5篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1991年   2篇
  1990年   1篇
  1988年   1篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   4篇
  1982年   4篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1968年   1篇
  1967年   4篇
排序方式: 共有315条查询结果,搜索用时 15 毫秒
221.
222.
Following the development of question-answering systems, consultation systems have emerged as a useful integration between data-base management, knowledge representation, and natural-language interaction with the computer. The idea developed in this paper is to insert in a consultation system an input language which is formal but natural-oriented. That is a feasible input, which allows a natural communication with the computer without involving too many theoretical difficulties and practical disadvantages in terms of cost and execution time. The paper illustrates an implementation based on the classical facilities of the goal-oriented languages. Using microplanner as implementation language, we directly obtain the deep structure of the input quasinatural language expressed in microplanner, and this makes the deduction activity more reliable and direct. The problems related to knowledge representation and basic functions of the system are discussed; examples of its use are illustrated.  相似文献   
223.
Two types of products obtained from the processing of Olea europaea cv ‘Taggiasca’ were monitored: pitted olives and olive paste preserved in monovarietal extra‐virgin olive oil of the same variety. The aim of this study was to follow the trends in the main physico‐chemical and sensory parameters related to the quality of these table olives and their covering oils, for simulation of the shelf‐life conditions. From all of the analyses carried out, it can be concluded that the optimum time of storage of these two products packaged in glass jars at room temperature (between 18 and 25 °C) and under artificial light and away from heat sources is approximately 9 months. After 9 months of storage, the covering oils were greatly affected by the contact with the broken fruit, which was accompanied by reductions in their antioxidant content due to the thermal treatment. The oxidative effects seen through physico‐chemical analyses are in agreement with the organoleptic analysis.  相似文献   
224.
Although the incremental sheet forming process results are widely investigated from the literature review, much more efforts are required to increase the industrial applicability of the process; first of all, the material failure for complex shapes need to be clarified. According to this aim, in this work, a preliminary analysis is carried out to detect the factors that deeply affect the process performance when a part having a changing transverse section has to be manufactured. Subsequently, a neural network approach is utilized to implement a ??ready to use?? procedure to predict failure in complex shapes.  相似文献   
225.
226.
227.
Diabetes affects different people of all ages, race, and sex. This is a condition characterized by a state of chronic hyperglycaemia that leads to an increase of intracellular oxidative stress linked to the overproduction of free radicals. In the present review, we focus our attention on the molecular mechanisms leading to oxidative stress-mediates complications with particular regard to central nervous system (CNS). Furthermore, the present review reports the effects of different kind of antioxidants with enzymatic and nonenzymatic action that may significantly decrease the intracellular free radicals' overproduction and prevents the hyperglycaemia-mediated complications.  相似文献   
228.
In this study, six enological tannins (T1–T6) from different source were analysed by selected analytical techniques, including UV–Vis, FTIR, NMR, SEC, LC-MS/MS and electronic nose. Moreover, the samples were tested for their antioxidant activity. Spectra and chromatograms are considered as a fingerprint with a pattern that is distinctive for a given type of sample. In particular, tannins showed the maximum UV–Vis absorbance (λmax) at 273–280 nm, the inflection point (λmin) at 247–264 nm, and the ratio λmax/λmin was 1.03, 1.35, 1.67, 1.36, 2.15, 2.02 for tannin T1–T6, respectively. The FTIR analysis of tannins showed the presence of most important absorption bands at 1522, 1453, 1380, 1350, 1328, 1286, 1210, 1148 and 1044 cm−1. Besides, SEC and NMR analysis allowed to sort the tannins according to their average DP as follows: T1 > T2 = T4 > T3 > T6 = T5. Based on this multiple techniques approach three condensed tannins (sample T3, T5 and T6) were clearly identified, together with two mixtures of hydrolysable tannins (sample T1 and T2), whereas one sample (T4) showed a peculiar pattern different from the commercial tannin commonly used in enology.  相似文献   
229.
Ketogenic diets (KDs) have shown beneficial effects in experimental models of neurodegeneration, designating aged individuals as possible recipients. However, few studies have investigated their consequences on aging brain. Here, late‐adult rats (19 months of age) were fed for 8 weeks with two medium chain triglycerides‐supplemented diets (MCT‐SDs) and the average area (S), numeric density (Nvs), and surface density (Sv) of synapses, as well as the average volume (V), numeric density (Nvm), and volume density (Vv) of synaptic mitochondria were evaluated in granule cell layer of the cerebellar cortex (GCL‐CCx) by computer‐assisted morphometric methods. MCT content was 10 or 20%. About 10%MCT‐SD induced the early appearance of senescent patterns (decreased Nvs and Nvm; increased V), whereas 20%MCT‐SD caused no changes. Recently, we have shown that both MCT‐SDs accelerate aging in the stratum moleculare of CA1 (SM CA1), but are “antiaging” in the outer molecular layer of dentate gyrus (OML DG). Since GCL‐CCx is more vulnerable to age than OML DG but less than SM CA1, present and previous results suggest that the effects of MCT‐SDs in the aging brain critically depend on neuronal vulnerability to age, besides MCT percentage. Microsc. Res. Tech. 2009. © 2009 Wiley‐Liss, Inc.  相似文献   
230.
This paper reports a molecular modelling study of the adsorption of protein subdomains with unlike secondary structures on different surfaces of ceramic titanium dioxide (TiO(2)), forming a passivating film on titanium biomaterials that provides the interface between the bulk metal and the physiological environment, affecting its biocompatibility and performance. Using molecular dynamics methods, we study the effect of the nanoscale structure of the common TiO(2) polymorphs (rutile, anatase and brookite) on the adsorption of an albumin subdomain and on two connected fibronectin modules, respectively containing α-helices and β-sheets. We find that the larger protein subdomain shows a stronger adsorption, as expected because of its size, but also that the three surfaces behave differently. In particular, brookite shows the weakest adsorption, whereas anatase leads to the strongest intrinsic adsorption, in particular for the fibronectin modules. Moreover, the simulations indicate a significant conformational change of the adsorbed protein subdomains with extensive surface nanopatterning. These results show that classical molecular dynamics methods can provide useful information about the influence of nanostructure and topology on protein physisorption at a fixed surface chemistry.  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