全文获取类型
收费全文 | 19022篇 |
免费 | 707篇 |
国内免费 | 44篇 |
专业分类
电工技术 | 237篇 |
综合类 | 24篇 |
化学工业 | 3741篇 |
金属工艺 | 470篇 |
机械仪表 | 400篇 |
建筑科学 | 958篇 |
矿业工程 | 108篇 |
能源动力 | 602篇 |
轻工业 | 1639篇 |
水利工程 | 172篇 |
石油天然气 | 68篇 |
无线电 | 1482篇 |
一般工业技术 | 3373篇 |
冶金工业 | 3436篇 |
原子能技术 | 116篇 |
自动化技术 | 2947篇 |
出版年
2023年 | 123篇 |
2022年 | 211篇 |
2021年 | 330篇 |
2020年 | 234篇 |
2019年 | 271篇 |
2018年 | 368篇 |
2017年 | 379篇 |
2016年 | 414篇 |
2015年 | 339篇 |
2014年 | 516篇 |
2013年 | 1223篇 |
2012年 | 827篇 |
2011年 | 1168篇 |
2010年 | 799篇 |
2009年 | 830篇 |
2008年 | 936篇 |
2007年 | 872篇 |
2006年 | 760篇 |
2005年 | 746篇 |
2004年 | 598篇 |
2003年 | 544篇 |
2002年 | 528篇 |
2001年 | 334篇 |
2000年 | 304篇 |
1999年 | 330篇 |
1998年 | 356篇 |
1997年 | 307篇 |
1996年 | 327篇 |
1995年 | 307篇 |
1994年 | 292篇 |
1993年 | 264篇 |
1992年 | 259篇 |
1991年 | 163篇 |
1990年 | 232篇 |
1989年 | 206篇 |
1988年 | 169篇 |
1987年 | 166篇 |
1986年 | 156篇 |
1985年 | 187篇 |
1984年 | 197篇 |
1983年 | 162篇 |
1982年 | 170篇 |
1981年 | 168篇 |
1980年 | 145篇 |
1979年 | 165篇 |
1978年 | 123篇 |
1977年 | 121篇 |
1976年 | 164篇 |
1975年 | 125篇 |
1973年 | 108篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Number entry is a ubiquitous activity and is often performed in safety- and mission-critical procedures, such as healthcare, science, finance, aviation and in many other areas. We show that Monte Carlo methods can quickly and easily compare the reliability of different number entry systems. A surprising finding is that many common, widely used systems are defective, and induce unnecessary human error. We show that Monte Carlo methods enable designers to explore the implications of normal and unexpected operator behaviour, and to design systems to be more resilient to use error. We demonstrate novel designs with improved resilience, implying that the common problems identified and the errors they induce are avoidable. 相似文献
2.
3.
4.
Paul Ocheje Ameh Nnabuk Okon Eddy 《Protection of Metals and Physical Chemistry of Surfaces》2018,54(6):1169-1181
Protection of Metals and Physical Chemistry of Surfaces - In this work, phthalic acid is investigated for its corrosion inhibition properties (for aluminum in solutions of HCl and H2SO4) through... 相似文献
5.
Greg A. Breed Paul M. Severns Andrew M. Edwards 《Journal of the Royal Society Interface》2015,12(103)
Lévy flights have gained prominence for analysis of animal movement. In a Lévy flight, step-lengths are drawn from a heavy-tailed distribution such as a power law (PL), and a large number of empirical demonstrations have been published. Others, however, have suggested that animal movement is ill fit by PL distributions or contend a state-switching process better explains apparent Lévy flight movement patterns. We used a mix of direct behavioural observations and GPS tracking to understand step-length patterns in females of two related butterflies. We initially found movement in one species (Euphydryas editha taylori) was best fit by a bounded PL, evidence of a Lévy flight, while the other (Euphydryas phaeton) was best fit by an exponential distribution. Subsequent analyses introduced additional candidate models and used behavioural observations to sort steps based on intraspecific interactions (interactions were rare in E. phaeton but common in E. e. taylori). These analyses showed a mixed-exponential is favoured over the bounded PL for E. e. taylori and that when step-lengths were sorted into states based on the influence of harassing conspecific males, both states were best fit by simple exponential distributions. The direct behavioural observations allowed us to infer the underlying behavioural mechanism is a state-switching process driven by intraspecific interactions rather than a Lévy flight. 相似文献
6.
7.
An introduction to Web Services 总被引:1,自引:0,他引:1
Paul Muschamp 《BT Technology Journal》2004,22(1):9-18
This paper provides an introduction to Web Services. A brief history of Web Services is given, leading into an overview of
the key Web Services technologies. The paper describes the way in which the IT industry has embraced Web Services and the
uses to which the technologies are currently being applied. It concludes with a view of the role of both the key developers
and standards bodies in the creation of Web Services and discusses the ways in which this process needs to be supported in
order for Web Services to evolve.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
Thomas S. Lowry John C. Bright Murray E. Close Christina A. Robb Paul A. White Stewart G. Cameron 《国际水资源开发杂志》2003,19(4):579-592
The primary objective of this project is to identify gaps, whether real or perceived, that hinder effective groundwater management in New Zealand. These gaps show as gaps in information, gaps in implementation, gaps in technological and management tools, and gaps in understanding of fundamental processes. The secondary objective is to propose a management strategy to close the identified gaps. Several methods are used to meet these objectives: surveys distributed to selected staff in each regional council; the review of various written reports; the analysis of land-use databases; and private consultation within each regional council. Results show that groundwater management in New Zealand is generally reactionary with the main gaps being in strategic planning and national guidelines. Most gaps appear to be predominantly information and implementation issues. In some cases there are gaps in the understanding of fundamental processes within an aquifer system, including the long-term effects of land-use on groundwater quality. An adaptive management approach is suggested as a means of closing these gaps. 相似文献
9.
McWayne Christine M.; Fantuzzo John W.; McDermott Paul A. 《Canadian Metallurgical Quarterly》2004,40(4):633
The present concurrent study combined developmental and ecological considerations to examine the unique contribution of multiple preschool competencies to an indicator of early academic success. Participants included 195 Head Start children from 32 classrooms representative of a large, urban Head Start program. Dimensional (variable-centered) analyses revealed 3 distinct classroom competency dimensions (i.e., General Classroom Competencies, Specific Approaches to Learning, and Interpersonal Classroom Behavioral Problems). The first 2 of these dimensions were found to be uniquely associated with early academic success. Findings from typological (person-centered) analyses supported the dimensional findings. Typological analyses revealed 7 profiles of classroom competency distinguished by high scores on the dimensions of General Competencies and Approaches to Learning, and these profiles were found to relate differentially to the indicator of early academic success. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
A new method has been developed for compressing the matrices that occur in most integral-equation-based computer programs. This method is easy to interface with existing computer programs, and allows them to run significantly faster and with significantly less memory. This method applies not only to electromagnetic and acoustic computation, but also to most programs involving a Green's function or any integral equation with a kernel having some smoothness properties. Our numerical computations, running on a high-end personal computer, have achieved compression ratios of fifty times, and compressed inversion of the matrices fifty times faster than by previous methods. For larger problems, solved on high-performance computers, these ratios would improve to about one thousand to one for larger moment method problems. 相似文献