全文获取类型
收费全文 | 84808篇 |
免费 | 1052篇 |
国内免费 | 408篇 |
专业分类
电工技术 | 791篇 |
综合类 | 2316篇 |
化学工业 | 11673篇 |
金属工艺 | 4807篇 |
机械仪表 | 3051篇 |
建筑科学 | 2170篇 |
矿业工程 | 567篇 |
能源动力 | 1208篇 |
轻工业 | 3701篇 |
水利工程 | 1300篇 |
石油天然气 | 342篇 |
无线电 | 9350篇 |
一般工业技术 | 16463篇 |
冶金工业 | 2689篇 |
原子能技术 | 262篇 |
自动化技术 | 25578篇 |
出版年
2023年 | 35篇 |
2022年 | 59篇 |
2021年 | 57篇 |
2020年 | 40篇 |
2019年 | 59篇 |
2018年 | 14496篇 |
2017年 | 13409篇 |
2016年 | 10002篇 |
2015年 | 642篇 |
2014年 | 282篇 |
2013年 | 299篇 |
2012年 | 3182篇 |
2011年 | 9473篇 |
2010年 | 8323篇 |
2009年 | 5603篇 |
2008年 | 6807篇 |
2007年 | 7826篇 |
2006年 | 154篇 |
2005年 | 1240篇 |
2004年 | 1148篇 |
2003年 | 1196篇 |
2002年 | 557篇 |
2001年 | 109篇 |
2000年 | 191篇 |
1999年 | 68篇 |
1998年 | 68篇 |
1997年 | 52篇 |
1996年 | 58篇 |
1995年 | 27篇 |
1994年 | 22篇 |
1993年 | 15篇 |
1992年 | 27篇 |
1991年 | 34篇 |
1990年 | 12篇 |
1988年 | 22篇 |
1969年 | 25篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 42篇 |
1965年 | 44篇 |
1963年 | 28篇 |
1962年 | 22篇 |
1961年 | 18篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Vijay Singh Sharanagat Prabhat K. Nema Lochan Singh Ankur Kumar 《International Journal of Food Science & Technology》2022,57(3):1654-1665
The effect of microwave roasting parameters (300, 450 and 600 W; 5, 10 and 15 min) on acrylamide content in sorghum grain was determined using High Pressure Liquid Chromatography (HPLC)-photo diode array (PDA) detector coupled with C-18 column. Samples roasted at 300 and 450 W did not possess acrylamide, whereas 600 W (15 min) favoured formation of 2740.19 µg/kg of acrylamide, levels far exceeding the defined European Union (EU) limits. The chronic daily intake (CDI) for acrylamide through consumption of such grain flour was 3.25–9.5-fold higher to Joint FAO/WHO Expert Committee on Food Additives (JECFA) defined high exposure limits. The margin of exposure (MOE) values ranged from 4.3 to 12.76 and from 11.07 to 32.27 for neoplastic and neurological effects, respectively, demonstrating high exposure and serious health concerns associated with dietary intake of this toxicant. This study assesses the risk for the Indian population and highlights the importance of optimising process parameters for food product to minimise such exposure risks. 相似文献
2.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms. 相似文献
3.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
4.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
5.
6.
7.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before. 相似文献
8.
In India, little attention has been paid on antimicrobial resistance (AMR) in the context of developing “One Health” approach. Hence, utilizing multi-disciplinary approach, we assess the AMR level and dynamics/pattern of multi-drug resistance (MDR) in Escherichia coli, Salmonella spp., and Staphylococcus aureus circulating over the different stages of poultry in India. A total of 342 isolates including E. coli (n = 143), Salmonella spp. (n = 104), and S. aureus (n = 95) were recovered from fecal (n = 80) and cecal (n = 80) samples of chicken, collected across the different poultry-retail shops and poultry-farms located at urban and rural areas of Rajasthan, India, respectively. High rates of AMR to drugs that are critically/highly important both in human and veterinary medicine were observed among all the isolates. Upward trends in AMR prevalence was observed in poultry-retail shops than in poultry-farms. Notably, >90% of all the isolates were MDR, of particular, pattern/prevalence of MDR was substantially varied across the poultry-farms vs. poultry-retail shops. Our results indicate AMR including MDR to be common in E. coli, Salmonella spp., and S. aureus distributed frequently in poultry. The study encourages the formulation of national policy, programmes and further research with a “One Health” approach that can benefits to the human/animal and the environment. 相似文献
9.
High‐performance thermosets with tailored properties derived from methacrylated eugenol and epoxy‐based vinyl ester 下载免费PDF全文
Yuehong Zhang Yuzhan Li Vijay Kumar Thakur Zhenhua Gao Jiyou Gu Michael R Kessler 《Polymer International》2018,67(5):544-549
A renewable chemical, eugenol, is methacrylated to produce methacrylated eugenol (ME) employing the Steglich esterification reaction without any solvent. The resulting ME is used as a low‐viscosity co‐monomer to replace styrene in a commercial epoxy‐based vinyl ester resin (VE). The volatility and viscosity of ME and styrene are compared. The effect of ME loading and temperature on the viscosity of the VE–ME resin is investigated. Moreover, the thermomechanical properties, curing extent and thermal stability of the fully cured VE–ME thermosets are systematically examined. The results indicate that ME is a monomer with low volatility and low viscosity, and therefore the incorporation of ME monomer in VE resins allows significant reduction of viscosity. Moreover, the viscosity of the VE–ME resin can be tailored by adjusting the ME loadings and processing temperature to meet commercial liquid molding technology requirements. The glass transition temperatures of VE–ME thermosets range from 139 to 199 °C. In addition, more than 95% of the monomer is incorporated and fixed in the crosslinked network structure of VE–ME thermosets. Overall, the developed ME monomer exhibits promising potential for replacing styrene as an effective low‐viscosity co‐monomer. The VE–ME resins show great advantages for use in polymer matrices for high‐performance fiber‐reinforced composites. This work is of great significance to the vinyl ester industry by providing detailed experimental support. © 2018 Society of Chemical Industry 相似文献
10.