全文获取类型
收费全文 | 2339篇 |
免费 | 79篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 23篇 |
综合类 | 2篇 |
化学工业 | 360篇 |
金属工艺 | 36篇 |
机械仪表 | 43篇 |
建筑科学 | 200篇 |
矿业工程 | 4篇 |
能源动力 | 50篇 |
轻工业 | 204篇 |
水利工程 | 39篇 |
石油天然气 | 9篇 |
武器工业 | 1篇 |
无线电 | 136篇 |
一般工业技术 | 441篇 |
冶金工业 | 479篇 |
原子能技术 | 31篇 |
自动化技术 | 362篇 |
出版年
2022年 | 13篇 |
2021年 | 39篇 |
2020年 | 29篇 |
2019年 | 37篇 |
2018年 | 34篇 |
2017年 | 44篇 |
2016年 | 57篇 |
2015年 | 49篇 |
2014年 | 68篇 |
2013年 | 160篇 |
2012年 | 121篇 |
2011年 | 137篇 |
2010年 | 115篇 |
2009年 | 105篇 |
2008年 | 142篇 |
2007年 | 119篇 |
2006年 | 92篇 |
2005年 | 89篇 |
2004年 | 65篇 |
2003年 | 64篇 |
2002年 | 63篇 |
2001年 | 39篇 |
2000年 | 38篇 |
1999年 | 37篇 |
1998年 | 63篇 |
1997年 | 49篇 |
1996年 | 38篇 |
1995年 | 35篇 |
1994年 | 39篇 |
1993年 | 28篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 18篇 |
1989年 | 24篇 |
1988年 | 25篇 |
1987年 | 12篇 |
1986年 | 17篇 |
1985年 | 20篇 |
1984年 | 35篇 |
1983年 | 20篇 |
1982年 | 25篇 |
1981年 | 17篇 |
1980年 | 17篇 |
1979年 | 14篇 |
1978年 | 18篇 |
1977年 | 14篇 |
1976年 | 21篇 |
1975年 | 16篇 |
1974年 | 18篇 |
1973年 | 9篇 |
排序方式: 共有2420条查询结果,搜索用时 19 毫秒
92.
93.
Neil Jackson 《The Journal of Architecture》2013,18(2):196-224
The theme of this paper is the presence of the Japanese influence in the work of Charles Rennie Mackintosh and, in particular, the Glasgow School of Art. This has often been observed but never satisfactorily explained. Rather than simply listing the evidence, this paper investigates the relationship between him and Hermann Muthesius against the background of the time Muthesius spent working as an architect in Tokyo. Using the correspondence held in the Deutscher Werkbund Archiv, Berlin, as evidence of the close relationship between the two men and the others of The Four, this paper suggests that it was Muthesius's sensitivity to Japanese architecture which encouraged the direction of Mackintosh's work in the late 1890s and early 1900s and in so doing, offers an explanation of the more idiosyncratic and unexplained features of the library at the Glasgow School of Art. 相似文献
94.
Identifying a finite test set that adequately captures the essential behaviour of a program such that all faults are identified is a well‐established problem. This is traditionally addressed with syntactic adequacy metrics (e.g. branch coverage), but these can be impractical and may be misleading even if they are satisfied. One intuitive notion of adequacy, which has been discussed in theoretical terms over the past three decades, is the idea of behavioural coverage: If it is possible to infer an accurate model of a system from its test executions, then the test set can be deemed to be adequate. Despite its intuitive basis, it has remained almost entirely in the theoretical domain because inferred models have been expected to be exact (generally an infeasible task) and have not allowed for any pragmatic interim measures of adequacy to guide test set generation. This paper presents a practical approach to incorporate behavioural coverage. Our BESTEST approach (1) enables the use of machine learning algorithms to augment standard syntactic testing approaches and (2) shows how search‐based testing techniques can be applied to generate test sets with respect to this criterion. An empirical study on a selection of Java units demonstrates that test sets with higher behavioural coverage significantly outperform current baseline test criteria in terms of detected faults. © 2015 The Authors. Software Testing, Verification and Reliability published by John Wiley & Sons, Ltd. 相似文献
95.
Increasing awareness of the environmental impact of consumer and industrial products has produced a demand for lubricants that biodegrade. There is a number of biodegradation tests that can be used on lubricants, although not all are always appropriate, as this paper explains. The CEC test is among the best known and is in use for both conventional and synthetic oils. There will, in future, be a greater movement to biodegradable oils in Europe, perhaps extending to all oils. 相似文献
96.
97.
Polybrominated diphenyl ethers in the sediments of the Great Lakes. 3. Lakes Ontario and Erie 总被引:2,自引:0,他引:2
Song W Ford JC Li A Sturchio NC Rockne KJ Buckley DR Mills WJ 《Environmental science & technology》2005,39(15):5600-5605
Sediment cores were taken in 2002 in Lakes Ontario and Erie at four locations. A total of 48 sediment samples were characterized, dated using 210Pb, and analyzed for 10 congeners of polybrominated diphenyl ethers (PBDEs) including BDE209 as well as 39 congeners of polychlorinated biphenyls (PCBs). The surficial concentrations of nine tri- through hepta-BDE congeners (sigma9PBDE) are 4.85 and 6.33 ng g(-1), at sampling sites ON40 and ON30 in Lake Ontario, and 1.83 and 1.95 ng g(-1) at ER37 and ER09 in Lake Erie, respectively, based on dry sediment weight. The surficial BDE209 concentrations are 242 and 211 ng g(-1) at ON40 and ON30 and 50 and 55 ng g(-1) at ER37 and ER09. The sigma(9-) PBDEs fluxes to the sediment around 2002 are 147 and 195 pg cm(-2) year(-1) at ON40 and ON30 and 136 and 314 pg cm(-2) year(-1) at ER37 and ER09, respectively. The fluxes of BDE209 are 6.5 and 7.3 ng cm(-2) year(-1) at ON30 and ON40 and 3.7 and 8.9 ng cm(-2) year(-1) at ER37 and ER09, respectively. Dramatic increases in PBDE concentrations and fluxes upward toward the sediment surface and the present time are evident at both locations in Lake Ontario, while PCBs concentrations peak in the middle of sediment cores around the dated time of 1970s and 1960s. For both locations of Lake Erie, the increasing trends of both PBDEs and PCBs from the bottom to the surficial segments were distorted by sediment mixing. BDE209 is the most abundant congener among PBDEs in the sediments, constituting about 96 and 91% of the total PBDEs on mass basis in Lakes Ontario and Erie, respectively. 相似文献
98.
Robert C. Pullar Yong Zhang Lifeng Chen Shoufeng Yang Julian R.G. Evans Peter Kr. Petrov Andrei N. Salak Dmitry A. Kiselev Andrei L. Kholkin Victor M. Ferreira Neil McN. Alford 《Journal of the European Ceramic Society》2007,27(16):4437-4443
Applying combinatorial methods to materials science offers the opportunity to accelerate the discovery of more efficient dielectric ceramics. High-throughput methods have the potential to investigate the effects of a wide range of dopants on the dielectric properties, and to optimise existing systems, encouraging the short innovation cycles that the communications technology industry requires. The London University Search Instrument (LUSI) is a fully automated, high-throughput combinatorial robot that has the potential capability to produce large numbers of sintered bulk ceramic samples with varying composition in 1 day, as combinatorial libraries on alumina substrates. Ba1−xSrxTiO3 (BST) libraries were produced by LUSI as a proof-of-principle, with x = 0–1 in steps of 0.1, and fired to 1350 and 1400 °C for 1 h. Part I of this paper described the manufacture and physical characterisation of BST libraries, showing a regular change in composition with x across the libraries. In this second part, the dielectric properties of BST libraries produced by LUSI are assessed at frequencies between 100 Hz and 1 MHz, and at temperatures between 150 and 500 K. Local piezoelectric properties were also characterised by scanning probe microscope (SPM). All measurements showed evidence of a clear functional gradient varying with x across the library, with measured r corresponding to expected values for BST. 相似文献
99.
To facilitate molecular spectroscopic observation of the mysterious transition of dissolved sodium silicate molecules into
nanoparticles of desired silica gel and zeolite structures, the IR and Raman spectra of Na2H2SiO4 monomers are studied here in details. It is demonstrated that the 3–0.2 mol/L aqueous solutions of Na2SiO3 and Na2SiO3 × 9H2O contain mostly Na2H2SiO4 monomers dissociated about 30%–80%, respectively. In contrast to the common belief the Si–O vibrations of these monomers
depend on their dissociation level generating FTIR and Raman bands which are frequently associated with polymer silica structures
in the current literature. To stay consistent with the molweight and dissociation measurements, these vibrational assignments
are revised in this paper. Some unique and unexpected effects of D2O used instead of H2O as solvent are also reported. 相似文献
100.
世界保护与展示中心将提供世界顶级的设施,以确保大英博物馆更好的为后代保管和研究藏品。[The WCEC]will provide world class facilities that will allow the British Museum to ensure the care and understanding of its collections for future generations. 背景BACKGROUND世界保护与展览中心(WCEC)是大英博物馆260年来最大的再开发项目。该中心位于布鲁姆斯伯里地块的西北角,它将设置新的主展厅、最先进的实验室和工作室、世界顶级的藏品库以及博物馆,为英国乃至全球提供藏品租赁的设施。设计面临的挑战是:既要体现时代特征和大英博物馆的国际水准,又要达到其作为一级保护建筑在遗产保护方面更为宽泛的制度和建筑要求。 相似文献