全文获取类型
收费全文 | 1156篇 |
免费 | 47篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 2篇 |
化学工业 | 245篇 |
金属工艺 | 20篇 |
机械仪表 | 20篇 |
建筑科学 | 120篇 |
矿业工程 | 1篇 |
能源动力 | 29篇 |
轻工业 | 111篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 114篇 |
一般工业技术 | 191篇 |
冶金工业 | 90篇 |
原子能技术 | 19篇 |
自动化技术 | 216篇 |
出版年
2023年 | 17篇 |
2022年 | 19篇 |
2021年 | 36篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 14篇 |
2017年 | 17篇 |
2016年 | 39篇 |
2015年 | 27篇 |
2014年 | 34篇 |
2013年 | 62篇 |
2012年 | 45篇 |
2011年 | 84篇 |
2010年 | 59篇 |
2009年 | 65篇 |
2008年 | 60篇 |
2007年 | 58篇 |
2006年 | 51篇 |
2005年 | 49篇 |
2004年 | 41篇 |
2003年 | 31篇 |
2002年 | 28篇 |
2001年 | 22篇 |
2000年 | 19篇 |
1999年 | 15篇 |
1998年 | 36篇 |
1997年 | 32篇 |
1996年 | 19篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1970年 | 4篇 |
1942年 | 3篇 |
1941年 | 7篇 |
1940年 | 10篇 |
1939年 | 10篇 |
排序方式: 共有1205条查询结果,搜索用时 31 毫秒
101.
Amir Fahmi Torsten Pietsch Maria Bryszewska José Carlos Rodríguez‐Cabello Aneta Koceva‐Chyla Francisco Javier Arias Matilde Alonso Rodrigo Nabil Gindy 《Advanced functional materials》2010,20(6):1011-1018
The design and synthesis of nanostructured functional hybrid biomaterials are essential for the next generation of advanced diagnostics and the treatment of disease. A simple route to fabricate semiconductor nanofibers by self‐assembled, elastin‐like polymer (ELP)‐templated semiconductor nanoparticles is reported. Core–shell nanostructures of CdSe nanoparticles with a shell of ELPs are used as building blocks to fabricate functional one‐dimensional (1D) nanostructures. The CdSe particles are generated in situ within the ELP matrix at room temperature. The ELP controls the size and the size‐distribution of the CdSe nanoparticles in an aqueous medium and simultaneously directs the self‐assembly of core–shell building blocks into fibril architectures. It was found that the self‐assembly of core–shell building blocks into nanofibers is strongly dependent on the pH value of the medium. Results of cytotoxicity and antiproliferation of the CdSe‐ELP nanofibers demonstrate that the CdSe‐ELP does not exhibit any toxicity towards B14 cells. Moreover, these are found to be markedly capable of crossing the cell membrane of B14. In contrast, unmodified CdSe nanoparticles with ELPs cause a strong toxic response and reduction in the cell proliferation. This concept is valid for the fabrication of a variety of metallic and semiconductor 1D‐architectures. Therefore, it is believed that these could be used not only for biomedical purposes but for application in a wide range of advanced miniaturized devices. 相似文献
102.
Over the last few decades, vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) have emerged as multifaceted players in not only the pathogenesis, but potential treatment, of numerous diseases. They activate diverse intracellular signaling cascades known to have extensive crosstalk, and have been best studied for their effects in cardiology and cancer biology. Recent work with the two factors indicates that the activity of one growth factor is often directly related to the action of the other. Their respective neuroprotective effects, in particular, raise important questions regarding the treatment of neurodegenerative disorders, including Parkinson's disease. 相似文献
103.
Heat storage based on particulate materials is a promising option to provide a demand-oriented electricity production with utility-scale solar power plants. For energy storage discharge, a moving bed heat exchanger is considered and its design is investigated. As a basis for a flexible design tool, a multiphase model based on the Eulerian continuum approach was set up to describe the bulk flow and the thermal performance. The model was applied to an example heat exchanger layout, and the simulation results were compared with an empirical model, confirming the validity of the approach. Initial parameter variations identify the key parameters and their effect on the thermal performance. 相似文献
104.
Several dietary and host related factors potentially influencing carotenoid (beta-carotene, lutein and zeaxanthin) bioaccessibility from spinach, including different concentrations of sodium, calcium and magnesium, were systematically investigated by means of an in vitro digestion model. Bioaccessibility was highest when milk (4% fat) and lowest when skimmed milk or more complex food matrices such as sausage were added to the meal. Micellarisation significantly depended on the presence and concentration of bile salts and pancreatin (p < 0.001, Bonferroni) but was unaffected by pepsin. Micellarisation significantly decreased to 61.4 ± 3.0% of control (p < 0.001, Dunnett’s) at high cholesterol (114 mg/test meal) but not at similar stigmasterol concentrations. Calcium and magnesium ?13.8 mM individually inhibited micelle formation ( >40% on average), presumably due to the generation of insoluble soaps with fatty acids and bile salts. Increased sodium concentrations (280 and 460 mM) altered carotenoid micellarisation patterns, favoring beta-carotene isomers (p < 0.001, Bonferroni) but decreasing lutein and zeaxanthin (p < 0.001 and p < 0.05, respectively, Bonferroni). This study suggests that minerals may impact carotenoid bioavailability. 相似文献
105.
In this paper a method to check the solvability of a set of linear equations in the (max, min, +) algebra is described. Then, extensions to dynamic (or periodic) systems in the (max, min, +) algebra are provided. Further, some results regarding the uniqueness of solutions in both cases are given. Finally, we address a more general quasi periodic problem and provide an algorithm for its solution. 相似文献
106.
107.
108.
Hertwig Ralph; Herzog Stefan M.; Schooler Lael J.; Reimer Torsten 《Canadian Metallurgical Quarterly》2008,34(5):1191
Boundedly rational heuristics for inference can be surprisingly accurate and frugal for several reasons. They can exploit environmental structures, co-opt complex capacities, and elude effortful search by exploiting information that automatically arrives on the mental stage. The fluency heuristic is a prime example of a heuristic that makes the most of an automatic by-product of retrieval from memory, namely, retrieval fluency. In 4 experiments, the authors show that retrieval fluency can be a proxy for real-world quantities, that people can discriminate between two objects' retrieval fluencies, and that people's inferences are in line with the fluency heuristic (in particular fast inferences) and with experimentally manipulated fluency. The authors conclude that the fluency heuristic may be one tool in the mind's repertoire of strategies that artfully probes memory for encapsulated frequency information that can veridically reflect statistical regularities in the world. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
109.
ABSTRACT Multi-functional radial jet reattachment blow boxes deliver a dry air into the pockets of the dryer section of a paper machine by impinging directly onto the unsuppned sheet in the open diaw. The air flow also maintains or improves the sheet swbility. The iadial jet reattachment blow box technology pmvides a significant enhancement in drying rates. The theoretical drying results are presented in terms of average drying rates, moisture and temperature pmfiles along the drying section with and without the presence of the multi-functional radial jet reaaachment blow boxes. The thcorclical results indicate that enhancements of drying rates within the range of 8% to 25% are feasible depending on ihe operating conditions and machine configuration. 相似文献
110.
A system identification method for errors-in-variables problems based on covariance matching was recently proposed. In the first step, a small amount of covariances of noisy input–output data are computed, and then a parametric model is fitted to these covariances. In this paper, the method is further analyzed and the asymptotic accuracy of the parameter estimates is derived. An explicit algorithm for computing the asymptotic covariance matrix of the parameter estimates is given, and the identification method is shown to be asymptotically statistically efficient assuming that the given information is the computed covariances. As an important byproduct, an efficient algorithm is presented for computing the covariance matrix of the computed input–output covariances. 相似文献