全文获取类型
收费全文 | 435篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 187篇 |
金属工艺 | 5篇 |
机械仪表 | 6篇 |
建筑科学 | 25篇 |
能源动力 | 16篇 |
轻工业 | 73篇 |
水利工程 | 3篇 |
武器工业 | 1篇 |
无线电 | 15篇 |
一般工业技术 | 57篇 |
冶金工业 | 7篇 |
自动化技术 | 55篇 |
出版年
2022年 | 20篇 |
2021年 | 31篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 15篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 34篇 |
2012年 | 31篇 |
2011年 | 17篇 |
2010年 | 22篇 |
2009年 | 18篇 |
2008年 | 14篇 |
2007年 | 14篇 |
2006年 | 13篇 |
2005年 | 7篇 |
2004年 | 8篇 |
2003年 | 23篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1973年 | 3篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有455条查询结果,搜索用时 15 毫秒
441.
Marek Kosmulski Ryszard Dobrowolski Mieczysław Jaroniec Jerzy Szczypa 《Materials Chemistry and Physics》1984,11(2):195-200
The dependence of the isotope exchange kinetic curves on is studied, where I∞ denotes the equilibrium activity and Io is the initial activity of the solution. Experimental kinetic curves of isotope exchange of Cd (II) ions between the bulk solution and the surface layer formed on aluminium oxide and activated carbon (charcoal) are compared with theoretical calculations. 相似文献
442.
443.
A new method for optimizing complex engineering designs is presented that is based on the Learnable Evolution Model (LEM), a recently developed form of non‐Darwinian evolutionary computation. Unlike conventional Darwinian‐type methods that execute an unguided evolutionary process, the proposed method, called LEMd, guides the evolutionary design process using a combination of two methods, one involving computational intelligence and the other involving encoded expert knowledge. Specifically, LEMd integrates two modes of operation, Learning Mode and Probing Mode. Learning Mode applies a machine learning program to create new designs through hypothesis generation and instantiation, whereas Probing Mode creates them by applying expert‐suggested design modification operators tailored to the specific design problem. The LEMd method has been used to implement two initial systems, ISHED1 and ISCOD1, specialized for the optimization of evaporators and condensers in cooling systems, respectively. The designs produced by these systems matched or exceeded in performance the best designs developed by human experts. These promising results and the generality of the presented method suggest that LEMd offers a powerful new tool for optimizing complex engineering systems. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 1217–1248, 2006. 相似文献
444.
A new class of evolutionary computation processes is presented, called Learnable Evolution Model or LEM. In contrast to Darwinian-type evolution that relies on mutation, recombination, and selection operators, LEM employs machine learning to generate new populations. Specifically, in Machine Learning mode, a learning system seeks reasons why certain individuals in a population (or a collection of past populations) are superior to others in performing a designated class of tasks. These reasons, expressed as inductive hypotheses, are used to generate new populations. A remarkable property of LEM is that it is capable of quantum leaps (insight jumps) of the fitness function, unlike Darwinian-type evolution that typically proceeds through numerous slight improvements. In our early experimental studies, LEM significantly outperformed evolutionary computation methods used in the experiments, sometimes achieving speed-ups of two or more orders of magnitude in terms of the number of evolutionary steps. LEM has a potential for a wide range of applications, in particular, in such domains as complex optimization or search problems, engineering design, drug design, evolvable hardware, software engineering, economics, data mining, and automatic programming. 相似文献
445.
New generalized Newtonian fluid models for quantitative description of complex viscous behavior in shear flows
下载免费PDF全文
![点击此处可从《Polymer Engineering and Science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Two semiempirical models of generalized Newtonian fluid are discussed. Special attention was focused on the stress dependent model based on the free volume theory. However, the strain‐rate dependent model in form of a modified viscosity function resulting from Oldroyd equation is also presented. Both models (along with specific cases) reflecting pseudoplastic or dilatant behavior of liquids in shear flows are generalized to multimode models (defined as products of two or more basic models), which are able to describe quantitatively the behavior of more complex systems, for example, systems with pseudoplastic and dilatant properties in different shear stress (shear rate) ranges. A number of practical examples for viscosity curves of non‐Newtonian fluids described by these models are given. The questions of inverse models and model efficiency are also discussed. POLYM. ENG. SCI., 58:1446–1455, 2018. © 2017 Society of Plastics Engineers 相似文献
446.
The reinforcement role of single‐walled carbon nanotubes (SWCNT) in a high‐performance epoxy resin is studied in this article, with the emphasis on the deformation and load transfer mechanism. Tensile tests show that introducing carbon nanotubes (CNTs) into the epoxy resin changes the tensile strength of the material, and that the increase of Young's modulus is in good agreement with the increasing of glass transition temperature (Tg) measured by differential scanning calorimetry (DSC). Residual strains in CNTs induced during curing process have been investigated both experimentally and theoretically. Raman spectroscopy study shows that load transfers more efficiently in tension than in compression. The Raman shifts of deformed CNTs under repeated loading indirectly reveals that the load can be further transferred via friction after debonding fully occurs. Thin epoxy layers were observed on the pull out ends of CNTs, which implies the existence of the immobilized epoxy layer between CNTs and bulk epoxy. POLYM. COMPOS., 36:2212–2219, 2015. © 2014 Society of Plastics Engineers 相似文献
447.
Anna Zadlo Dr. Dominik Koszelewski Filip Borys Prof. Ryszard Ostaszewski 《Chembiochem : a European journal of chemical biology》2015,16(4):677-682
Mixed carbonates of 7‐hydroxy‐4‐methylcoumarin were shown to be a new class of probe for fluorogenic assays. They are promising substrates for fingerprinting enzyme hydrolytic activity, and proved particularly useful because of the low level of nonspecific degradation and ease of synthesis. They are highly relevant for screening lipase and esterase libraries. These advantages make umbelliferyl carbonates highly suitable substrates for high‐throughput screening. Moreover, we report the use of chiral fluorogenic carbonates as enantiopreference probes. 相似文献
448.
Z. egarska Ryszard Rafaowski Ryszard Amarowicz Magdalena Karama Fereidoon Shahidi 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1998,206(2):99-102
The antioxidative activity of the ethanolic extract of deodorized rosemary (Rosmarinus officinalis L.) in butter was tested. The extract was added at two concentrations, 0.05 and 0.1%, to the cream before churning. The samples
of isolated fat were stored at 60°C for 38 days and their peroxide values (PVs) determined periodically. The relative changes
in the proton absorption patterns of the butter lipids during storage were monitored by nuclear magnetic resonance (NMR) spectroscopy.
The samples treated with 0.05 and 0.1% extract had much longer induction periods than the control. A significant correlation
(r = 0.980) was measured between the ratio of aliphatic to olefinic protons (R
ao) and the PVs of the butter fat. The deodorized ethanolic extract was also subjected to TLC separation on silica gel plates
and UV spectral analysis. The UV spectrum of the extract had maxima at 286 and 328 nm. Six spots attributed to phenolic compounds
were observed on the TLC plate. The extract also exhibited strong antioxidant activity in a β-carotene-linoleate model system.
Received: 11 July 1997 相似文献
449.
450.
Piotr Pawlicki Anna Galuszka Laura Pardyak Ryszard Tuz Bartosz J. Pachno Martyna Malopolska Klaudia Dubniewicz Ping Yang Malgorzata Kotula-Balak Kazimierz Tarasiuk 《International journal of molecular sciences》2022,23(11)
Porker immunocastration against gonadoliberin (GnRH) secretion has been utilized since 2009; however, consumers are still skeptical of it. This is due to not having full information available on the problem of a boar taint, as well as a lack of research on morphological and molecular changes that may occur in the animal reproductive system and other body systems. The present study aimed to explore the functional status of steroidogenic Leydig cells of the testicular interstitial tissue in immunocastrated Polish Landrace pigs. Analyses were performed using Western blot, immunohistochemistry for relaxin (RLN), insulin-like 3 protein (INSL3), pelleted growth factor receptor α (PDGFRα), cytochrome P450scc, 3β- and 17β-hydroxysteroid dehydrogenases (3β-HSD, 17β-HSD), cytochrome P450arom, and 5α-reductase (5α-RED). Immunoassay ELISA was used to measure the androstenone, testosterone, and estradiol levels in the testis and serum of immunocastrates. We revealed disturbances in the distribution and expression of (i) RLN, indicating an inflammatory reaction in the interstitial tissue; (ii) INSL3 and PDGFRα, indicating alterations in the differentiation and function of fetal, perinatal, or adult Leydig cell populations; (iii) P450scc, 3β-HSD, 17β-HSD, P450arom, and 5α-RED, indicating disturbances in the sex steroid hormone production and disturbed functional status of Leydig cells; as well as (iv) decreased levels of androstenone, testosterone, and estradiol in testicular tissue and serum, indicating the dedicated action of Improvac to reduce boar taint at both the hypothalamic–hypophysis–gonadal axis and local level (Leydig cells). In summary, our study provides a significant portion of knowledge on the function of Leydig cells after immunocastration, which is also important for the diagnosis and therapy of testis dysfunction due to GnRH action failure and/or Leydig cell differentiational–functional alterations. 相似文献