全文获取类型
收费全文 | 657篇 |
免费 | 35篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 31篇 |
综合类 | 2篇 |
化学工业 | 114篇 |
金属工艺 | 16篇 |
机械仪表 | 35篇 |
建筑科学 | 18篇 |
矿业工程 | 13篇 |
能源动力 | 46篇 |
轻工业 | 13篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 57篇 |
一般工业技术 | 140篇 |
冶金工业 | 116篇 |
原子能技术 | 16篇 |
自动化技术 | 69篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 15篇 |
2019年 | 10篇 |
2018年 | 35篇 |
2017年 | 20篇 |
2016年 | 22篇 |
2015年 | 13篇 |
2014年 | 24篇 |
2013年 | 30篇 |
2012年 | 43篇 |
2011年 | 39篇 |
2010年 | 23篇 |
2009年 | 27篇 |
2008年 | 30篇 |
2007年 | 17篇 |
2006年 | 18篇 |
2005年 | 8篇 |
2004年 | 16篇 |
2003年 | 14篇 |
2002年 | 8篇 |
2001年 | 16篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 29篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1982年 | 3篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 4篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1962年 | 4篇 |
排序方式: 共有693条查询结果,搜索用时 15 毫秒
11.
OBJECTIVE: The present study examined Web-based information retrieval as a function of age for two information organization schemes: hierarchical organization and one organized around tags or keywords. BACKGROUND: Older adults' performance in information retrieval tasks has traditionally been lower compared with younger adults'. The current study examined the degree to which information organization moderated age-related performance differences on an information retrieval task. The theory of fluid and crystallized intelligence may provide insight into different kinds of information architectures that may reduce age-related differences in computer-based information retrieval performance. METHOD: Fifty younger (18-23 years of age) and 50 older (55-76 years of age) participants browsed a Web site for answers to specific questions. Half of the participants browsed the hierarchically organized system (taxonomy), which maintained a one-to-one relationship between menu link and page, whereas the other half browsed the tag-based interface, with a many-to-one relationship between menu and page. This difference was expected to interact with age-related differences in fluid and crystallized intelligence. RESULTS: Age-related differences in information retrieval performance persisted; however, a tag-based retrieval interface reduced age-related differences, as compared with a taxonomical interface. CONCLUSION: Cognitive aging theory can lead to interface interventions that reduce age-related differences in performance with technology. In an information retrieval paradigm, older adults may be able to leverage their increased crystallized intelligence to offset fluid intelligence declines in a computer-based information search task. APPLICATION: More research is necessary, but the results suggest that information retrieval interfaces organized around keywords may reduce age-related differences in performance. 相似文献
12.
Jungkyu Kim Michael Junkin Deok-Ho Kim Seunglee Kwon Young Shik Shin Pak Kin Wong Bruce K. Gale 《Microfluidics and nanofluidics》2009,7(2):149-167
Biosensors based on nanotechnology are rapidly developing and are becoming widespread in the biomedical field and analytical
chemistry. For these nanobiosensors to reach their potential, they must be integrated with appropriate packaging techniques,
which are usually based on nano/microfluidics. In this review we provide a summary of the latest developments in nanobiosensors
with a focus on label-based (fluorescence and nanoparticle) and label-free methods (surface plasmon resonance, micro/nanocantilever,
nanowires, and nanopores). An overview on how these sensors interface with nano/microfluidics is then presented and the latest
papers in the area summarized. 相似文献
13.
14.
Kim Kihyeun Son Myungwoo Pak Yusin Chee Sang-Soo Auxilia Francis Malar Lee Byung-Kee Lee Sungeun Kang Sun Kil Lee Chaedeok Lee Jeong Soo Kim Ki Kang Jang Yun Hee Lee Byoung Hun Jung Gun-Young Ham Moon-Ho 《Nano Research》2018,11(7):3957-3957
Nano Research - The order of the authors in the original version of this article was unfortunately incorrect on the first page and the first page of the ESM. Instead of Myungwoo Son1, Yusin Pak1,... 相似文献
15.
Microfluidic-based biosensors toward point-of-care detection of nucleic acids and proteins 总被引:1,自引:1,他引:0
Seokheun Choi Michael Goryll Lai Yi Mandy Sin Pak Kin Wong Junseok Chae 《Microfluidics and nanofluidics》2011,10(2):231-247
This article reviews state-of-the-art microfluidic biosensors of nucleic acids and proteins for point-of-care (POC) diagnostics.
Microfluidics is capable of analyzing small sample volumes (10−9–10−18 l) and minimizing costly reagent consumption as well as automating sample preparation and reducing processing time. The merger
of microfluidics and advanced biosensor technologies offers new promises for POC diagnostics, including high-throughput analysis,
portability and disposability. However, this merger also imposes technological challenges on biosensors, such as high sensitivity
and selectivity requirements with sample volumes orders of magnitude smaller than those of conventional practices, false response
errors due to non-specific adsorption, and integrability with other necessary modules. There have been many prior review articles
on microfluidic-based biosensors, and this review focuses on the recent progress in last 5 years. Herein, we review general
technologies of DNA and protein biosensors. Then, recent advances on the coupling of the biosensors to microfluidics are highlighted.
Finally, we discuss the key challenges and potential solutions for transforming microfluidic biosensors into POC diagnostic
applications. 相似文献
16.
Driving characteristics of the electrowetting-on-dielectric device using atomic-layer-deposited aluminum oxide as the dielectric 总被引:2,自引:1,他引:1
Jong-hyeon Chang Dae Young Choi Seungoh Han James Jungho Pak 《Microfluidics and nanofluidics》2010,8(2):269-273
Electrowetting on dielectric (EWOD) is useful in manipulating droplets for digital (droplet-based) microfluidics, but its high driving voltage over several tens of volts has been a barrier to overcome. This article presents the characteristics of EWOD device with aluminum oxide (Al2O3, ε r ≈ 10) deposited by atomic layer deposition (ALD), for the first time as the high-k dielectric for lowering the EWOD driving voltage substantially. The EWOD device of the single-plate configuration was fabricated by several steps for the control electrode array of 1 mm × 1 mm squares with 50 μm space, the dielectric layer of 1,270 Å thick ALD Al2O3, the reference electrode of 20 μm wide line electrode, and the hydrophobic surface treatment by Teflon-AF coating, respectively. We observed the movement of a 2 μl water droplet in an air environment, applying a voltage between one of the control electrodes and the reference electrode in contact with the droplet. The droplet velocity exponentially depending on the applied voltage below 15 V was obtained. The measured threshold voltage to move the droplet was as low as 3 V which is the lowest voltage reported so far in the EWOD researches. This result opens a possibility of manipulating droplets, without any surfactant or oil treatment, at only a few volts by EWOD using ALD Al2O3 as the dielectric. 相似文献
17.
18.
This study examined the use of deliberately anthropomorphic automation on younger and older adults' trust, dependence and performance on a diabetes decision-making task. Research with anthropomorphic interface agents has shown mixed effects in judgments of preferences but has rarely examined effects on performance. Meanwhile, research in automation has shown some forms of anthropomorphism (e.g. etiquette) have effects on trust and dependence on automation. Participants answered diabetes questions with no-aid, a non-anthropomorphic aid or an anthropomorphised aid. Trust and dependence in the aid was measured. A minimally anthropomorphic aide primarily affected younger adults' trust in the aid. Dependence, however, for both age groups was influenced by the anthropomorphic aid. Automation that deliberately embodies person-like characteristics can influence trust and dependence on reasonably reliable automation. However, further research is necessary to better understand the specific aspects of the aid that affect different age groups. Automation that embodies human-like characteristics may be useful in situations where there is under-utilisation of reasonably reliable aids by enhancing trust and dependence in that aid. Practitioner Summary: The design of decision-support aids on consumer devices (e.g. smartphones) may influence the level of trust that users place in that system and their amount of use. This study is the first step in articulating how the design of aids may influence user's trust and use of such systems. 相似文献
19.
The formation of alkylperoxy radicals on catalysts CuCr2O4/ -Al2O3, Pt /--Al2O3 and on alumina upon the interaction of amines and alcohols with oxygen has been observed applying the matrix isolation ESR technique. Surface-generated gas phase radicals are shown to initiate a radical chain reaction. The efficiency of the yield of radicals depends on the catalyst mass and its arrangement in a reactor: the desorption of radicals into the gas phase occurs primarily from the outer geometrical surface of catalyst granules. 相似文献
20.
Modeling and measurement of simultaneous switching noise coupling through signal via transition 总被引:1,自引:0,他引:1
Jongbae Park Hyungsoo Kim Youchul Jeong Jingook Kim Jun So Pak Dong Gun Kam Joungho Kim 《Advanced Packaging, IEEE Transactions on》2006,29(3):548-559
The signal via is a heavily utilized interconnection structure in high-density System-on-Package (SoP) substrates and printed circuit boards (PCBs). Vias facilitate complicated routings in these multilayer structures. Significant simultaneous switching noise (SSN) coupling occurs through the signal via transition when the signal via suffers return current interruption caused by reference plane exchange. The coupled SSN decreases noise and timing margins of digital and analog circuits, resulting in reduction of achievable jitter performance, bit error ratio (BER), and system reliability. We introduce a modeling method to estimate SSN coupling based on a balanced transmission line matrix (TLM) method. The proposed modeling method is successfully verified by a series of time-domain and frequency-domain measurements of several via transition structures. First, it is clearly verified that SSN coupling causes considerable clock waveform distortion, increases jitter and noise, and reduces margins in pseudorandom bit sequence (PRBS) eye patterns. We also note that the major frequency spectrum component of the coupled noise is one of the plane pair resonance frequencies in the PCB power/ground pair. Furthermore, we demonstrate that the amount of SSN noise coupling is strongly dependent not only on the position of the signal via, but also on the layer configuration of the multilayer PCB. Finally, we have successfully proposed and confirmed a design methodology to minimize the SSN coupling based on an optimal via positioning approach. 相似文献