全文获取类型
收费全文 | 6393篇 |
免费 | 757篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 58篇 |
综合类 | 117篇 |
化学工业 | 1780篇 |
金属工艺 | 96篇 |
机械仪表 | 114篇 |
建筑科学 | 254篇 |
矿业工程 | 16篇 |
能源动力 | 751篇 |
轻工业 | 658篇 |
水利工程 | 42篇 |
石油天然气 | 16篇 |
无线电 | 631篇 |
一般工业技术 | 1053篇 |
冶金工业 | 711篇 |
原子能技术 | 56篇 |
自动化技术 | 820篇 |
出版年
2022年 | 55篇 |
2021年 | 65篇 |
2020年 | 73篇 |
2019年 | 113篇 |
2018年 | 135篇 |
2017年 | 147篇 |
2016年 | 184篇 |
2015年 | 238篇 |
2014年 | 253篇 |
2013年 | 398篇 |
2012年 | 270篇 |
2011年 | 337篇 |
2010年 | 486篇 |
2009年 | 421篇 |
2008年 | 577篇 |
2007年 | 239篇 |
2006年 | 247篇 |
2005年 | 196篇 |
2004年 | 198篇 |
2003年 | 182篇 |
2002年 | 190篇 |
2001年 | 121篇 |
2000年 | 133篇 |
1999年 | 105篇 |
1998年 | 121篇 |
1997年 | 91篇 |
1996年 | 103篇 |
1995年 | 85篇 |
1994年 | 96篇 |
1993年 | 81篇 |
1992年 | 72篇 |
1991年 | 51篇 |
1990年 | 71篇 |
1989年 | 71篇 |
1988年 | 49篇 |
1987年 | 50篇 |
1986年 | 47篇 |
1985年 | 72篇 |
1984年 | 61篇 |
1983年 | 63篇 |
1982年 | 52篇 |
1981年 | 49篇 |
1980年 | 49篇 |
1979年 | 59篇 |
1978年 | 31篇 |
1977年 | 45篇 |
1976年 | 40篇 |
1975年 | 41篇 |
1974年 | 31篇 |
1973年 | 27篇 |
排序方式: 共有7173条查询结果,搜索用时 15 毫秒
61.
Daniel Serrano Jean Peyrelasse Christian Boned Daniel Harran Philippe Monge 《应用聚合物科学杂志》1990,39(3):679-693
The percolation model has been applied to the study of gelation of the TGDDM-DDS system (tetraglycidyldiaminodiphenylmethane–diaminodiphenylsulfone) at a mass concentration of 100–30. For each temperature the experimental viscosity curves are satisfactorily described by a percolation law. Using the degree of chemical reactions, X, as a variable, a very clear change in the reaction mechanism with temperature can be shown. Then a rate of advancement of effective reactions, Y, is defined. This value only takes intermolecular-type reactions into account, and is probably the only variable on which viscosity depends in a percolation law: η = B(1 ? Y/Yc)?p. We obtain Yc= 0.45 and p= 2.0. Comparing Xc and Yc at the gel point, we obtain information on the proportion of intramolecular reactions with temperature. It is also demonstrated that the critical percolation threshold agrees closely with the gel point determined experimentally on log G″= f(t) curves. 相似文献
62.
A series of polymers based on methylmethacrylate, butylacrylate, and ω‐perfluorooctylalkylacrylate were prepared by radical polymerization. By changing both the length of the hydrocarbon spacer, between the fluorinated chain and the ester function of the fluorinated monomer, and its concentration, the surface properties of the resulting terpolymers were greatly influenced. Polymers containing small amounts of fluorinated comonomer units had considerably reduced surface energies compared to the copolymer poly (methylmethacrylate‐co‐butylacrylate) taken as reference. The outermost surface composition has been investigated by the XPS technique, confirming the strong fluorine enrichment. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 821–827, 2006 相似文献
63.
Nocturnal intragastric feeding has been shown to be an effective means to improve clinical and biochemical features in glycogen
storage disease type I (GSD-I). In this study, we investigated the fatty acid patterns in a whole plasma and in circulating
lipoproteins in patients on this therapy. The results demonstrated massive concentration of total fatty acids coupled with
higher levels of triglycerides, free cholesterol, cholesterol ester and phospholipids. This hyperlipidemia involved all fatty
acids without distinction of carbon or bond numbers. However, the increase was more pronounced for saturated than polyunsaturated
fatty acids, as was demonstrated by the ratios of both oleic acid to linoleic acid (1.91±0.40 vs 0.80±0.09 in controls) and
of ω3+ω6 to ω9 fatty acid families (0.92±0.11 vs 1.66±0.08 in controls). The fatty acid patterns in very low (VLDL), low (LDL)
and high (HDL) density lipoprotein showed substantial differences in composition, reflecting an association between an abnormal
lipoprotein pattern and essential fatty acid deficiency. Furthermore, GSD-I patients exhibited a significant increase in VLDL
(17±2 vs 47±7 mg/dl) and LDL cholesterol (124±7 vs 206±24 mg/dl), coupled with a decrease in HDL cholesterol (49±4 vs 28±3
mg/dl). These data documenting high LDL cholesterol and low HDL cholesterol associated with an increased concentration and
proportion of saturated fatty acids suggest that GSD-I patients on nocturnal intragastric feeding are at high risk for atherosclerosis
and its complications. 相似文献
64.
Abraho Silvia Insfran Emilio Sluters Arthur Vanderdonckt Jean 《Software and Systems Modeling》2021,20(5):1335-1349
Software and Systems Modeling - Adapting the user interface of a software system to the requirements of the context of use continues to be a major challenge, particularly when users become more... 相似文献
65.
Abdoul Bitar Stéphane Dauzère-Pérès Claude Yugma Renaud Roussel 《Journal of Scheduling》2016,19(4):367-376
In this paper, we propose a metaheuristic for solving an original scheduling problem with auxiliary resources in a photolithography workshop of a semiconductor plant. The photolithography workshop is often a bottleneck, and improving scheduling decisions in this workshop can help to improve indicators of the whole plant. Two optimization criteria are separately considered: the weighted flow time (to minimize) and the number of products that are processed (to maximize). After stating the problem and giving some properties on the solution space, we show how these properties help us to efficiently solve the problem with the proposed memetic algorithm, which has been implemented and tested on large generated instances. Numerical experiments show that good solutions are obtained within a reasonable computational time. 相似文献
66.
67.
Andre Suslik Spritzer Jeremy Boy Pierre Dragicevic Jean‐Daniel Fekete Carla Maria Dal Sasso Freitas 《Computer Graphics Forum》2015,34(3):461-470
Node‐link infographics are visually very rich and can communicate messages effectively, but can be very difficult to create, often involving a painstaking and artisanal process. In this paper we present an investigation of node‐link visualizations for communication and how to better support their creation. We begin by breaking down these images into their basic elements and analyzing how they are created. We then present a set of techniques aimed at improving the creation workflow by bringing more flexibility and power to users, letting them manipulate all aspects of a node‐link diagram (layout, visual attributes, etc.) while taking into account the context in which it will appear. These techniques were implemented in a proof‐of‐concept prototype called GraphCoiffure, which was designed as an intermediary step between graph drawing/editing software and image authoring applications. We describe how GraphCoiffure improves the workflow and illustrate its benefits through practical examples. 相似文献
68.
Lesa Lorenzen Huber Kalpana Shankar Kelly Caine Kay Connelly L. Jean Camp Beth Ann Walker 《International journal of human-computer interaction》2013,29(7):441-455
In-home technologies can support older adults' activities of daily living, provide physical safety and security, and connect elders to family and friends. They facilitate aging in place while reducing caregiver burden. One of older adults' primary concerns about in-home technologies is their potential to reduce human contact, particularly from cherished caregivers. In this exploratory in situ study, we provided an ecosystem of networked monitoring technologies to six older adults and their caregivers. We analyzed the amount and content of communication between them. The amount of noncomputer-mediated communication did not decrease through the 6-week study. The content of communication coalesced into four themes: communication about the technologies, communication facilitated by technologies, intrusiveness of technologies, and fun and playfulness with the technologies. Results suggest that in-home technologies, designed with sensitivity to older adults' primary motivations, have the potential to shape and tailor important relationships in later life. 相似文献
69.
Jean Sykes 《New Review of Information Networking》2013,18(1):23-30
This article begins by looking at changes in the student body in recent years as useful indicators of how libraries need to alter and adapt their student library provision. Among the concepts explored are the student as consumer-customer, the Google generation, greater than ever competition among students especially for the job market, new technology as fashion accessory as much as learning tool, the widening participation agenda for higher education, and the almost ubiquitous presence of multi-functional electronic devices. There is an examination of some challenges for librarians in meeting the needs and demands of this new generation of students. These include the balancing of electronic and print provision, the future of the physical library environment, push rather than pull to deliver library services, anytime anywhere access to information, integration with other university services, and helping to fit students for the world of work. The main message of the article is that librarians are not under threat from the giant search engines as long as they embrace the interactive technologies which students so willingly and expertly use, and adapt them to get library services out to students as customers. 相似文献
70.
Nadia Magnenat Thalmann Igor Sunday Pandzic Jean‐Claude Moussaly 《Digital Creativity》2013,24(2):59-66
Abstract This paper describes the making of a short film on the Xian terra‐cotta soldiers using our integrated HU‐MANOID software. The method of creating and animating the soldiers’ faces is first presented. Then, we show how our approach, based on metaballs and spline surfaces, was used for designing and deforming soldiers’ bodies. For the animation of the bodies, we describe the motion control methods. Clothes for the soldiers are then described as well as horses and decor design. For the rendering, we explained our strategy using parallel machines. Finally, problems of integration are addressed. 相似文献