全文获取类型
收费全文 | 5343篇 |
免费 | 419篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 66篇 |
综合类 | 7篇 |
化学工业 | 1639篇 |
金属工艺 | 61篇 |
机械仪表 | 105篇 |
建筑科学 | 211篇 |
矿业工程 | 10篇 |
能源动力 | 203篇 |
轻工业 | 709篇 |
水利工程 | 45篇 |
石油天然气 | 7篇 |
无线电 | 348篇 |
一般工业技术 | 1012篇 |
冶金工业 | 378篇 |
原子能技术 | 29篇 |
自动化技术 | 937篇 |
出版年
2024年 | 16篇 |
2023年 | 98篇 |
2022年 | 327篇 |
2021年 | 400篇 |
2020年 | 184篇 |
2019年 | 188篇 |
2018年 | 219篇 |
2017年 | 191篇 |
2016年 | 266篇 |
2015年 | 197篇 |
2014年 | 283篇 |
2013年 | 364篇 |
2012年 | 359篇 |
2011年 | 458篇 |
2010年 | 293篇 |
2009年 | 253篇 |
2008年 | 302篇 |
2007年 | 243篇 |
2006年 | 169篇 |
2005年 | 151篇 |
2004年 | 129篇 |
2003年 | 118篇 |
2002年 | 85篇 |
2001年 | 59篇 |
2000年 | 46篇 |
1999年 | 50篇 |
1998年 | 40篇 |
1997年 | 32篇 |
1996年 | 43篇 |
1995年 | 22篇 |
1994年 | 21篇 |
1993年 | 22篇 |
1992年 | 25篇 |
1991年 | 13篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 8篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1967年 | 2篇 |
1948年 | 1篇 |
排序方式: 共有5767条查询结果,搜索用时 15 毫秒
991.
992.
Andrea Martiradonna 《中国建筑装饰装修》2012,(11):68-73
这是位于意大利皮埃蒙特的加油站.除了满足一般加油站的功能性.它的设计还与旅行的概念紧密联系起来.成为旅行者驻足休憩的临时绿洲。这个服务站的设计与旅行的概念紧密联系起来.无论路程长短,都可以在此停下来休息一下再重新上路。与服务站连续的特点相同.它与沥青马路有一段距离,就像一条丝带环绕着加油站.创造了一个临时的”绿洲”.让旅行者得以在这里小憩。通常.加油站被认为是一种单纯具有支持功能的建筑.这个概念直接影响着建筑的外观设计。根据这一定义.建筑被设计成了静态的形式.与城市景观的连续、流动的概念紧密联系在一起。 相似文献
993.
Gasification of fuel cane bagasse, the waste residue from fuel cane, a hybrid of wild and commercial clones of sugar cane, was carried out in a novel 50 kWe air-blown autothermal downdraft gasifier. The speciation and distribution of alkali, alkali earth metals and major ash forming elements during gasification were investigated to evaluate the extent of volatilisation of these elements into the syngas and to determine the likely impact on syngas fuelled solid oxide fuel cell systems. Also assessed was the potential for defluidisation of the fuel bed due to agglomerate and deposit formation. Chemical fractionation studies showed that 30% of the potassium was captured by aluminosilicates and was retained in the ash, thereby reducing the alkali loading in the syngas and that more than 50% of the alkali earth metals were released to the syngas. In contrast, although the major ash forming elements were transformed from acid insoluble to acid soluble forms during gasification they remained hard bound in the ash and less than 30% of each one was released into the gas phase. The composition of clinkers and agglomerates produced during gasification was investigated by SEM-EDX and XRD which confirmed the presence of the eutectic systems KAlSi2O6–SiO2, KAlSi2O6–CaMgSi2O6–SiO2 and CaMgSi2O6–NaAlSi3O8. A preliminary model of the distribution behaviour during gasification of the ash forming elements has been developed. 相似文献
994.
Andrea Martinelli Massimo Calì Lucio D'Ilario Iolanda Francolini Antonella Piozzi 《应用聚合物科学杂志》2012,123(5):2697-2705
In the first part of this article, we reported the crystalline memory effect on the nonisothermal crystallization of poly(L ‐lactide). The experiments were carried out by using polymer single crystals growth from dilute solution as standard starting material. In this article (Part II), we have analyzed in detail the effect of the melting condition on the overall crystallization kinetics by applying the Nakamura‐Avrami model to DSC results. The absence or the low concentration of foreign infusible heterogeneous nuclei in our system allowed us to exalt the self‐nuclei role in polymer crystallization, to follow their concentration decrease during the melting process and to find the limiting melting temperature for their disappearance. Below such a temperature, a stable equilibrium number of self‐nuclei was observed, probably deriving from ordered structures, persisting in the melt, and originated from the single crystals thickening process during the polymer dynamic melting in the DSC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
995.
Andrea Monteagudo-Mera Leandro Rodríguez-Aparicio Javier Rúa Honorina Martínez-Blanco Nicolás Navasa María Rosario García-Armesto Miguel Ángel Ferrero 《Journal of Functional Foods》2012,4(2):531-541
Eleven lactic acid bacteria strains of importance to the dairy industry were subjected to in vitro analyses to determine their probiotic potential. Seven strains were isolated from ewe’s and cow’s milk (Enterococcus faecalis – five –, Lactococcus lactis and Lactobacillus paracasei). Four were obtained from American Type Culture Collection (ATCC), isolated from cheese (Lactobacillus casei 393), human feces (L. paracasei 27092 and Lactobacillus rhamnosus 53103) and used in cheese making (L. lactis 54104). Although none of the strains was able to degrade mucin, all E. faecalis showed, at least, one transferable antibiotic resistance, which excluded them as candidates for addition to foods. Of the remaining six safe strains, L. lactis strains were more tolerant to low pH than Lactobacillus spp.; all were tolerant to pancreatin and bile salts and showed antibacterial activity. The highest level of adhesion to Caco-2 cells was observed with L. lactis 660, even higher than L. rhamnosus ATCC 53103 (recognized probiotic and used as control). The physiological probiotic properties of these strains, mainly isolated from dairy sources, are interesting in view of their use in cheese productions as starter and non starter cultures. The five LAB safe strains studied may have potential as novel probiotics in the dairy foods. 相似文献
996.
997.
Bettina?C?mmererEmail author Katharina?Chodakowski Claudia?Gienapp Laura?Wohak Andrea?Hartwig Lothar?W.?Kroh 《European Food Research and Technology》2012,234(4):663-670
High molecular weight Maillard reaction products (melanoidins) are described to possess metal-chelating properties. Whereas
in food systems, this ability contributes to antioxidant properties, the consequences on biological systems are not quite
clear. The study was aimed to evaluate the implication of metal complexation by melanoidins on DNA damage. Melanoidins prepared
with d-glucose and different l-amino acids under water-free reaction conditions were charged with cupric ions. The effect on isolated DNA was investigated
by the PM2 assay and on cellular systems in the human colon carcinoma cell line HCT-116 by alkaline unwinding. Independent
of the amino acid composition, pure melanoidins (MW >14 kDa) did not cause significant DNA damage. By charging melanoidins
with Cu2+ ions, a considerable DNA strand breaking activity was detectable, which was again amplified in an oxidative milieu (addition
of hydrogen peroxide). Since Cu2+ normally does not provoke the formation of reactive oxygen species (ROS) via Fenton-type reaction, the results obtained have
to be attributed to reducing properties of melanoidins. Thus, in melanoidin–copper complexes redox cycling may take place
leading to Cu+ which subsequently undergoes Fenton-type and Haber–Weiss reactions. As a consequence, ROS are formed, which may explain the
generation of DNA strand breaks. 相似文献
998.
999.
The paper deals with the kinetics of the droplet epitaxial GaAs quantum ring formation grown on AlGaAs (0 0 1) surface. The observation is, that the aspect ratio of these nano structures is depends not only on the technological parameters but on the size of the initial droplet. Under appropriate growth conditions, the depressions, in the middle of the rings are deeper than the surface level of the substrate. A large number of tests show, that the depressions in the middle of the small rings are often deeper than that of the larger ones. The number is larger, than just statistical fluctuation. An explanation for this phenomenon and its kinetics are given in the paper, based on the size dependence of the material properties, like for instance solubility. The plausible explanation assumes is that the probability of the crystal seed formation in the larger droplets is higher. 相似文献
1000.
Del Favero S Facchinetti A Cobelli C 《IEEE transactions on bio-medical engineering》2012,59(5):1281-1290
In diabetes, the mean square error (MSE) metric is extensively used for assessing glucose prediction methods and identifying glucose models. One limitation of this metric is that, by equally treating errors in hypo-, eu-, and hyperglycemia, it is not able to weight the different clinical impact of errors in these three situations. In this paper, we propose a new cost function, which overcomes this limitation and can be used in place of MSE for several scopes, in particular for assessing the quality of glucose predictors and identifying glucose models. The new metric called glucose-specific MSE (gMSE) modifies MSE with a Clark error grid inspired penalty function, which penalizes overestimation in hypoglycemia and underestimation in hyperglycemia, i.e., the most harmful conditions on a clinical perspective. From a mathematical point of view, gMSE retains sensitivity of MSE and inherits some of its important mathematical features, in particular it has no local minima, simplifying the optimization. This makes it suitable for model identification purposes also. First, the goodness of it is demonstrated by means of three experiments, designed ad hoc to evidence its sensitivity to accuracy, precision, and distortion in glucose predictions. Second, a prediction assessment problem is presented, in which two real prediction profiles are compared. Results show that the MSE chooses the worst clinical situation, while gMSE correctly selects the situation with less clinical risk. Finally, we also demonstrate that models identified minimizing gMSE are more accurate in potentially harmful situations (hypo- and hyperglycemia) than those obtained by MSE. 相似文献