全文获取类型
收费全文 | 6637篇 |
免费 | 252篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 78篇 |
综合类 | 16篇 |
化学工业 | 1177篇 |
金属工艺 | 92篇 |
机械仪表 | 71篇 |
建筑科学 | 480篇 |
矿业工程 | 6篇 |
能源动力 | 145篇 |
轻工业 | 1004篇 |
水利工程 | 56篇 |
石油天然气 | 22篇 |
武器工业 | 1篇 |
无线电 | 355篇 |
一般工业技术 | 925篇 |
冶金工业 | 1681篇 |
原子能技术 | 71篇 |
自动化技术 | 712篇 |
出版年
2023年 | 28篇 |
2022年 | 87篇 |
2021年 | 184篇 |
2020年 | 86篇 |
2019年 | 85篇 |
2018年 | 112篇 |
2017年 | 130篇 |
2016年 | 145篇 |
2015年 | 134篇 |
2014年 | 174篇 |
2013年 | 249篇 |
2012年 | 281篇 |
2011年 | 366篇 |
2010年 | 268篇 |
2009年 | 240篇 |
2008年 | 286篇 |
2007年 | 430篇 |
2006年 | 228篇 |
2005年 | 190篇 |
2004年 | 168篇 |
2003年 | 170篇 |
2002年 | 146篇 |
2001年 | 115篇 |
2000年 | 103篇 |
1999年 | 138篇 |
1998年 | 426篇 |
1997年 | 269篇 |
1996年 | 179篇 |
1995年 | 140篇 |
1994年 | 118篇 |
1993年 | 120篇 |
1992年 | 63篇 |
1991年 | 61篇 |
1990年 | 69篇 |
1989年 | 62篇 |
1988年 | 49篇 |
1987年 | 50篇 |
1986年 | 42篇 |
1985年 | 55篇 |
1984年 | 33篇 |
1983年 | 35篇 |
1982年 | 30篇 |
1981年 | 35篇 |
1980年 | 41篇 |
1979年 | 42篇 |
1978年 | 22篇 |
1977年 | 46篇 |
1976年 | 56篇 |
1974年 | 24篇 |
1973年 | 28篇 |
排序方式: 共有6892条查询结果,搜索用时 218 毫秒
121.
We describe a neural network able to rapidly establish correspondence between neural feature layers. Each of the network's two layers consists of interconnected cortical columns, and each column consists of inhibitorily coupled subpopulations of excitatory neurons. The dynamics of the system builds on a dynamic model of a single column, which is consistent with recent experimental findings. The network realizes dynamic links between its layers with the help of specialized columns that evaluate similarities between the activity distributions of local feature cell populations, are subject to a topology constraint, and can gate the transfer of feature information between the neural layers. The system can robustly be applied to natural images, and correspondences are found in time intervals estimated to be smaller than 100 ms in physiological terms. 相似文献
122.
Christiane Gresse von Wangenheim Marcello Thiry Djone Kochanski 《Empirical Software Engineering》2009,14(4):418-452
Software measurement is considered important in improving the software process. However, teaching software measurement remains
a challenging issue. Although, games and simulations are regarded powerful tools for learning, their learning effectiveness
is not rigorously established. This paper describes the results of an explorative study to investigate the learning effectiveness
of a game prototype on software measurement in order to make an initial judgment about its potential as an educational tool
as well as to analyze its appropriateness, engagement and strengths & weaknesses as guidance for further evolution. Within
the study, a series of experiments was conducted in parallel in three master courses in Brazil. Results of the study reveal
that the participants consider the content and structure of the game appropriate, but no indication for a significant difference
on learning effectiveness could be shown.
相似文献
Djone KochanskiEmail: |
123.
124.
Cutting efficiency loss of #15 H-type and K-type files was studied as a function of bulk plastic deformation and cutting edge wear. Instrumentation was done by purely extractive filing, without any significant torsional and/or bending strain. Cutting efficiency variations were assessed by means of cutting force measurement, while absolute cutting efficiency was obtained through three-dimensional scanning stylus profilometry. Bulk plastic deformation-induced flute modifications may lower the cutting efficiency of H-type files by approximately 50%. For this instrument special care is required in tip and flute machining to avoid in vivo breakage. On the contrary, within the normal life-span of an instrument of approximately 100 strokes cutting edge wear is seen to be negligible. The existence of such wear is "inferred" indirectly from a 10% drop in extraction efficiency. 相似文献
125.
126.
Bacterial populations associated with poultry processing were determined on neck skin samples, equipment surfaces and environmental samples by replicate surveys. Aerobic plate counts, Enterobacteriaceae counts, Enterobacteriaceae counts and Pseudomonas counts were performed by standard procedures and the prevalence of Listeria, presumptive Salmonella and Staphylococcus aureus determined. Statistically significant (P < 0.05) increases in counts of all types of bacteria were obtained on product samples as a result of processing. Although bacterial counts on neck skin samples decreased by 0.3 to 0.4 log CFU g-1 after spray washing of carcasses, subsequent spinchilling and packaging of whole carcasses resulted in 0.7 to 1.2 log CFU g-1 increases. Bacterial numbers on equipment surfaces, however, decreased significantly from the "dirty" to the "clean" areas of the abattoir. Transport cages, "rubber fingers", defeathering curtains, shackles and conveyor belts repeatedly showed aerobic plate counts in excess of 5.0 log CFU 25 cm-2. Aerobic plate counts of scald tank and spinchiller water were 2 log CFU ml-1 higher than those of potable water samples. Bacterial numbers of the air in the "dirty" area were higher than those of the "clean" area. Listeria, presumptive Salmonella and Staphylococcus aureus were isolated from 27.6, 51.7 and 24.1% of all product samples, respectively, and Listeria and Staphylococcus aureus were also isolated from selected equipment surfaces. 相似文献
127.
Jeanne Volatron Florent Carn Jelena Kolosnjaj‐Tabi Yasir Javed Quoc Lam Vuong Yves Gossuin Christine Ménager Nathalie Luciani Gaëlle Charron Miryana Hémadi Damien Alloyeau Florence Gazeau 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(2)
Proteins implicated in iron homeostasis are assumed to be also involved in the cellular processing of iron oxide nanoparticles. In this work, the role of an endogenous iron storage protein—namely the ferritin—is examined in the remediation and biodegradation of magnetic iron oxide nanoparticles. Previous in vivo studies suggest the intracellular transfer of the iron ions released during the degradation of nanoparticles to endogenous protein cages within lysosomal compartments. Here, the capacity of ferritin cages to accommodate and store the degradation products of nanoparticles is investigated in vitro in the physiological acidic environment of the lysosomes. Moreover, it is questioned whether ferritin proteins can play an active role in the degradation of the nanoparticles. The magnetic, colloidal, and structural follow‐up of iron oxide nanoparticles and proteins in lysosome‐like medium confirms the efficient remediation of potentially harmful iron ions generated by nanoparticles within ferritins. The presence of ferritins, however, delays the degradation of particles due to a complex colloidal behavior of the mixture in acidic medium. This study exemplifies the important implications of intracellular proteins in processes of degradation and metabolization of iron oxide nanoparticles. 相似文献
128.
Tissue Engineering: Effective Light Directed Assembly of Building Blocks with Microscale Control (Small 24/2017)
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
129.
130.
Researchers on organisational ambidexterity have proposed several solutions to address the potential conflicts between exploration activities and exploitation activities. Unlike simultaneous ambidexterity, sequential ambidexterity – defined as temporal switching between exploration and exploitation – has not been examined fully, and the conditions under which this temporal switching can be successful are unclear. This paper proposes the concept of temporal switching capability to better understand the process by which sequential ambidexterity is executed. In addition, we hypothesise that performance effects are contingent upon firm-specific factors: a firm’s business strategy and absorptive capacity. Utilising three sources of data – a secondary database, annual reports and a survey administered to 145 firms in the electronics industry with 10-year observations – we find support for our hypotheses. The results show that the temporal switching capability positively relates to new product performance and that business strategy type and absorptive capacity have moderating effects. The results are meaningful in both theory and practice. 相似文献