全文获取类型
收费全文 | 89640篇 |
免费 | 1196篇 |
国内免费 | 425篇 |
专业分类
电工技术 | 955篇 |
综合类 | 2321篇 |
化学工业 | 12428篇 |
金属工艺 | 4945篇 |
机械仪表 | 3127篇 |
建筑科学 | 2467篇 |
矿业工程 | 598篇 |
能源动力 | 1232篇 |
轻工业 | 4147篇 |
水利工程 | 1305篇 |
石油天然气 | 362篇 |
武器工业 | 1篇 |
无线电 | 9805篇 |
一般工业技术 | 17060篇 |
冶金工业 | 3929篇 |
原子能技术 | 309篇 |
自动化技术 | 26270篇 |
出版年
2022年 | 60篇 |
2021年 | 88篇 |
2020年 | 76篇 |
2019年 | 90篇 |
2018年 | 14566篇 |
2017年 | 13459篇 |
2016年 | 10052篇 |
2015年 | 700篇 |
2014年 | 381篇 |
2013年 | 462篇 |
2012年 | 3398篇 |
2011年 | 9644篇 |
2010年 | 8532篇 |
2009年 | 5814篇 |
2008年 | 7072篇 |
2007年 | 7986篇 |
2006年 | 362篇 |
2005年 | 1463篇 |
2004年 | 1272篇 |
2003年 | 1337篇 |
2002年 | 694篇 |
2001年 | 223篇 |
2000年 | 305篇 |
1999年 | 187篇 |
1998年 | 384篇 |
1997年 | 238篇 |
1996年 | 202篇 |
1995年 | 153篇 |
1994年 | 117篇 |
1993年 | 121篇 |
1992年 | 91篇 |
1991年 | 93篇 |
1990年 | 72篇 |
1989年 | 68篇 |
1988年 | 59篇 |
1986年 | 51篇 |
1985年 | 52篇 |
1983年 | 46篇 |
1982年 | 46篇 |
1981年 | 49篇 |
1979年 | 56篇 |
1977年 | 52篇 |
1976年 | 97篇 |
1968年 | 57篇 |
1966年 | 52篇 |
1965年 | 46篇 |
1958年 | 45篇 |
1957年 | 47篇 |
1955年 | 66篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Nazir Kizzie‐Hayford Doris Jaros Yvonne Schneider Harald Rohm 《International Journal of Food Science & Technology》2015,50(2):381-388
A standard method for the extraction of tiger nut milk has been introduced. It has been shown that, although milling duration improves the yield of tiger nut milk solids and its nutrient composition, there is a quantifiable loss of nutrient in the pressing residue during milk extraction. Milling duration improved the colloidal stability of the milk against creaming during 16 h of storage. A higher milling intensity resulted in the aggregation of biological polymers which resulted in colloidal destabilisation. Milling improved the lightness and stability and reduced browning rate of the tiger nut milk during storage. This report is important for the production of tiger nut milk of consistent and comparable characteristics. Milling has been introduced as a processing method for the qualitative and quantitative modulation of the properties of tiger nut milk. It is recommended to develop further strategies to improve the colloidal stability of tiger nut milk as a beverage. 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.
Daniel Biedermann Jan Schneider Hendrik Drachsler 《Journal of Computer Assisted Learning》2021,37(5):1217-1231
Digital distractions can interfere with goal attainment and lead to undesirable habits that are hard to get red rid of. Various digital self-control interventions promise support to alleviate the negative impact of digital distractions. These interventions use different approaches, such as the blocking of apps and websites, goal setting, or visualizations of device usage statistics. While many apps and browser extensions make use of these features, little is known about their effectiveness. This systematic review synthesizes the current research to provide insights into the effectiveness of the different kinds of interventions. From a search of the ‘ACM’, ‘Springer Link’, ‘Web of Science’, ’IEEE Xplore’ and ‘Pubmed’ databases, we identified 28 digital self-control interventions. We categorized these interventions according to their features and their outcomes. The interventions showed varying degrees of effectiveness, and especially interventions that relied purely on increasing the participants' awareness were barely effective. For those interventions that sanctioned the use of distractions, the current literature indicates that the sanctions have to be sufficiently difficult to overcome, as they will otherwise be quickly dismissed. The overall confidence in the results is low, with small sample sizes, short study duration, and unclear study contexts. From these insights, we highlight research gaps and close with suggestions for future research. 相似文献
9.
10.