全文获取类型
收费全文 | 22784篇 |
免费 | 883篇 |
国内免费 | 83篇 |
专业分类
电工技术 | 293篇 |
综合类 | 44篇 |
化学工业 | 5147篇 |
金属工艺 | 479篇 |
机械仪表 | 460篇 |
建筑科学 | 1718篇 |
矿业工程 | 160篇 |
能源动力 | 686篇 |
轻工业 | 2135篇 |
水利工程 | 182篇 |
石油天然气 | 56篇 |
武器工业 | 1篇 |
无线电 | 1483篇 |
一般工业技术 | 4165篇 |
冶金工业 | 2770篇 |
原子能技术 | 137篇 |
自动化技术 | 3834篇 |
出版年
2023年 | 152篇 |
2022年 | 308篇 |
2021年 | 533篇 |
2020年 | 312篇 |
2019年 | 327篇 |
2018年 | 493篇 |
2017年 | 425篇 |
2016年 | 530篇 |
2015年 | 479篇 |
2014年 | 689篇 |
2013年 | 1506篇 |
2012年 | 1081篇 |
2011年 | 1521篇 |
2010年 | 1092篇 |
2009年 | 1043篇 |
2008年 | 1265篇 |
2007年 | 1098篇 |
2006年 | 939篇 |
2005年 | 865篇 |
2004年 | 774篇 |
2003年 | 688篇 |
2002年 | 661篇 |
2001年 | 392篇 |
2000年 | 377篇 |
1999年 | 412篇 |
1998年 | 409篇 |
1997年 | 371篇 |
1996年 | 341篇 |
1995年 | 294篇 |
1994年 | 301篇 |
1993年 | 298篇 |
1992年 | 250篇 |
1991年 | 214篇 |
1990年 | 201篇 |
1989年 | 230篇 |
1988年 | 186篇 |
1987年 | 177篇 |
1986年 | 174篇 |
1985年 | 239篇 |
1984年 | 214篇 |
1983年 | 184篇 |
1982年 | 168篇 |
1981年 | 195篇 |
1980年 | 130篇 |
1979年 | 147篇 |
1978年 | 143篇 |
1977年 | 127篇 |
1976年 | 138篇 |
1975年 | 120篇 |
1974年 | 105篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
202.
203.
204.
205.
We propose a newO(p
3
n
2) algorithm for solving complexnp×np linear systems that have block Hankel structure, where the blocks are square matrices of sizep×p. Via FFTs the block Hankel system is transformed into a block Loewner system. An inversion formula enables us to calculate
the inverse of the block Loewner matrix explicitely. The parameters that occur in this inversion formula are calculated by
solving two rational interpolation problems on the unit circle. We have implemented our algorithm in Fortran 90. Numerical
examples are included. 相似文献
206.
M Thiel C Zourelidis JD Chambers UH von Andrian KE Arfors K Messmer K Peter 《Canadian Metallurgical Quarterly》1997,29(3):160-175
Adhesion molecules on polymorphonuclear leukocytes (PMNL) play an important role in nonspecific defense mechanisms directed at invading microorganisms. When local infection, however, cannot be controlled, a systemic inflammatory response syndrome (SIRS) ensues which may progress to septic shock and multiple organ failure, these being major determinants of the patient's outcome. In the present study, the expression of beta 2-integrins and L-selectin on blood PMNL was measured on subsequent days in patients with sepsis (n = 17) and in healthy volunteers (n = 15). beta 2-Integrins and L-selectin molecules were detected by flow cytometry, using the monoclonal antibodies IB4 (anti-CD18) and Dreg200 (anti-CD62L), respectively. Adhesion molecules were determined at baseline immediately after blood collection and also 45 min after incubation of cells in vitro at body temperature to allow for spontaneous regulation. In addition, PMNL were activated by receptor-dependent and receptor-independent stimuli to characterize stimulus-specific adhesion molecule expression. In parallel with the measurement of adhesion molecules, severity of sepsis was assessed by the Elebute score. The results demonstrate significant differences in the basal, spontaneous and stimulus-induced expression of adhesion molecules between healthy volunteers, survivors (n = 11) and nonsurvivors (n = 6). Moreover, when survivors and nonsurvivors with severe sepsis (Elebute score > 12) were compared, basal expressions of both beta 2-integrins and L-selectin were significantly lower in patients who did not survive. Thus, measurement of adhesion molecules on circulating PMNL may be useful to identify septic patients at high risk for lethal outcome. 相似文献
207.
The introduction of automatic display layout (ADL), i.e. the automatic placing and sizing of windows in a window-oriented graphical user interface, is a major contribution towards an improved user interface. Our approach to ADL is to treat this problem as a combinatorial optimization problem. In this article we describe the concepts we used for implementing an experimental system which controls the computer screen contents and its layout. We give two examples of different standard applications into which we included ADL successfully, namely hypertext for a window layout problem and graph-browser for a hierarchical graph layout problem within a particular window. The results show that automatic (and tool independent) display layout will be possible in the near future even in an interactive environment. 相似文献
208.
209.
210.
Tracy L. Westeyn Gregory D. Abowd Thad E. Starner Jeremy M. Johnson Peter W. Presti Kimberly A. Weaver 《Personal and Ubiquitous Computing》2012,16(2):169-191
Previous research has established the connection between the way in which children interact with objects and the potential
early identification of children with autism. Those findings motivate our own work to develop "smart toys," objects embedded with wireless sensors that are safe and enjoyable for very small children, that allow detailed interaction
data to be easily recorded. These sensor-enabled toys provide opportunities for autism research by reducing the effort required
to collect and analyze a child’s interactions with objects. In the future, such toys may be a useful part of clinical and
in-home assessment tools. In this paper, we discuss the design of a collection of smart toys that can be used to automatically
characterize the way in which a child is playing. We use statistical models to provide objective, quantitative measures of
object play interactions. We also developed a tool to view rich forms of annotated play data for later analysis. We report
the results of recognition experiments on more than fifty play sessions conducted with adults and children as well as discuss
the opportunities for using this approach to support video annotation and other applications. 相似文献