全文获取类型
收费全文 | 3708篇 |
免费 | 166篇 |
国内免费 | 7篇 |
学科分类
工业技术 | 3881篇 |
出版年
2023年 | 17篇 |
2022年 | 24篇 |
2021年 | 63篇 |
2020年 | 52篇 |
2019年 | 70篇 |
2018年 | 102篇 |
2017年 | 119篇 |
2016年 | 107篇 |
2015年 | 97篇 |
2014年 | 114篇 |
2013年 | 283篇 |
2012年 | 229篇 |
2011年 | 284篇 |
2010年 | 220篇 |
2009年 | 196篇 |
2008年 | 260篇 |
2007年 | 222篇 |
2006年 | 210篇 |
2005年 | 159篇 |
2004年 | 115篇 |
2003年 | 117篇 |
2002年 | 124篇 |
2001年 | 75篇 |
2000年 | 76篇 |
1999年 | 65篇 |
1998年 | 47篇 |
1997年 | 52篇 |
1996年 | 46篇 |
1995年 | 45篇 |
1994年 | 32篇 |
1993年 | 20篇 |
1992年 | 30篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 20篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1972年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有3881条查询结果,搜索用时 234 毫秒
991.
A fundamental aspect of many multiplayer online games is the ability to trade items between players. Trading may occur with items that were found in the virtual environment, included as pieces of the game, or purchased by the player as assets. Regardless of the types of items, any multiplayer game that supports trading or exchanging items in the game must do so in a secure manner. We have developed a protocol to solve the problem of secure peer-to-peer trading in games in which the primary concern is that items are exchanged fairly, and additionally that items are not duplicated. Our protocol enables one-way and two-way trades and can be extended to multi-item trades in both small- and large-scale games where trades last only for the duration of a session or are persistent. We show that our protocol addresses the security threats which it might encounter, and then provide an analysis to demonstrate its scalability. 相似文献
992.
Chris JenkinsAuthor Vitae 《Computer Fraud & Security》2012,2012(8):18-20
993.
Huang X Miao H Nelson J Turner J Steinbrener J Shapiro D Kirz J Jacobsen C 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,638(1):171-175
Cryogenic microscopy allows one to view frozen hydrated biological and soft matter specimens with good structural preservation and a high degree of stability against radiation damage. We describe a liquid nitrogen-cooled anti-contamination device for cryogenic X-ray diffraction microscopy. The anti-contaminator greatly reduces the buildup of ice layers on the specimen due to condensation of residual water vapor in the experimental vacuum chamber. We show by coherent X-ray diffraction measurements that this leads to fivefold reduction of background scattering, which is important for far-field X-ray diffraction microscopy of biological specimens. 相似文献
994.
995.
Chris Melvin Eifion Jewell Jakob Miedema Koen Lammers Arnoud de Vooys Andrew Allman Neil McMurray 《Packaging Technology and Science》2019,32(7):345-355
Tinplate surface morphology and chemistry is adjusted during the manufacturing process in order to meet the demands of its subsequent product use, the commonest being visual appearance and food packaging stability. A comprehensive experimental study on an industrial tinning line varied the surface roughness and the tin coating weight with the characterization through X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), white light interferometer (WLI), optical imaging, and lacquer adhesion measurement. Increasing tin weight lowers the adhesion through the production of a thicker disorganized tin oxide layer which has a greater tendency to fracture under shearing forces. There is no evidence that the substrate roughness improves the adhesion of the lacquer. Analysis of the failure location identifies fracture in the tin oxide layer below the passivation layer. The findings have impacts on the next generation of passivation materials for tinplate as it has been clearly demonstrated that growth in tin oxide thickness, particularly when unstructured, has a detrimental impact on lacquer adhesion. 相似文献
996.
997.
998.
Phoebe Louiseanne Heseltine Joseph Hosken Chris Agboh David Farrar Shervanthi Homer‐Vanniasinkam Mohan Edirisinghe 《大分子材料与工程》2019,304(1)
Silk has attracted considerable interest for use in biomedical applications due to its high strength and promising biocompatibility. Degummed silk, consisting only of silk fibroin (SF), has been processed using various methods and can be made into films, sponges, and fibers. Pressurized gyration (PG) is capable of rapidly producing aligned fibers and offers a great amount of control over their structure and morphology. Here, SF fibers are produced for the first time using PG. The effect of varying SF concentration and applied working pressure to the gyration vessel is reported, along with the resulting effect on fiber diameter, morphology, and structural composition. Aligned microfibers are found at concentrations of 8, 10, 12 w/v%, with the lowest fiber diameters reported at 8 w/v% SF 0.3 MPa applied pressure (2.1 ± 1.3 µm). Fourier‐transform infrared spectroscopy (FTIR) confirms the existence of PG spun fibers in both random coil and β‐sheet formations. 相似文献
999.
1000.
Ioannis Ieropoulos Pavlina Theodosiou Benjamin Taylor John Greenman Chris Melhuish 《International Journal of Hydrogen Energy》2017,42(3):1783-1790
The microbial fuel cell (MFC) is an energy transducer that can directly produce electricity from bacterial oxidation of organic matter. MFCs consist of two reaction chambers (anode and cathode) separated by a semipermeable membrane. This study describes the work carried out towards the optimization of critical MFC components, with 3D fabricated materials. The response of the optimized fuel cells, which were fed with soft materials such as gelatin, alginate and Nafion?, is also reported. The optimised components were the membrane and the cathode electrode. A conventional Nafion membrane was substituted with a custom made terracotta sheet and the electrode used was a single sheet of carbon veil coated with an activated carbon paste. The results showed that among the soft materials tested within the anodic chamber, gelatin performed the best; it also revealed that even after a 10-day starvation period gelatin demonstrated better longevity. These results show that MFCs have the potential to be 3D-printed monolithically using the EVOBOT platform. 相似文献