全文获取类型
收费全文 | 1280篇 |
免费 | 76篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 16篇 |
综合类 | 1篇 |
化学工业 | 295篇 |
金属工艺 | 16篇 |
机械仪表 | 34篇 |
建筑科学 | 19篇 |
矿业工程 | 2篇 |
能源动力 | 27篇 |
轻工业 | 126篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 291篇 |
一般工业技术 | 252篇 |
冶金工业 | 176篇 |
原子能技术 | 6篇 |
自动化技术 | 100篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 21篇 |
2021年 | 32篇 |
2020年 | 15篇 |
2019年 | 25篇 |
2018年 | 35篇 |
2017年 | 31篇 |
2016年 | 33篇 |
2015年 | 21篇 |
2014年 | 43篇 |
2013年 | 59篇 |
2012年 | 56篇 |
2011年 | 98篇 |
2010年 | 55篇 |
2009年 | 50篇 |
2008年 | 77篇 |
2007年 | 62篇 |
2006年 | 50篇 |
2005年 | 35篇 |
2004年 | 32篇 |
2003年 | 43篇 |
2002年 | 44篇 |
2001年 | 31篇 |
2000年 | 43篇 |
1999年 | 36篇 |
1998年 | 52篇 |
1997年 | 52篇 |
1996年 | 39篇 |
1995年 | 17篇 |
1994年 | 20篇 |
1993年 | 25篇 |
1992年 | 16篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1974年 | 7篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1364条查询结果,搜索用时 15 毫秒
991.
Molybdenum Sulphoselenophosphide Spheroids as an Effective Catalyst for Hydrogen Evolution Reaction
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)
Ranjith Bose Vasanth Rajendiran Jothi Beomsoo Koh Chiyoung Jung Sung Chul Yi 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(8)
Electrocatalytic splitting of water is the most convincing and straight forward path to extract hydrogen, but the efficiency of this process relies heavily on the catalyst employed. Here, molybdenum sulphoselenophosphide (MoS45.1Se11.7P6.1) spheroids are reported as an active catalyst for the hydrogen evolution reaction (HER) and this is the first attempt to study on ternary anion based molybdenum chalcogenides. As‐prepared MoSxSeyPz catalyst reveals a unique morphology of microspheroids capped by stretched‐out nanoflakes that exhibits excellent electrocatalytic activity ( j—10 mA cm?2 @ 93 mV, Tafel slope of 50.1 mV dec?1, TOF—0.40 s?1) fairly closer to the performance of platinum (Pt) and predominant to those of the pre‐existing Mo‐chalcogenides and phosphides. Such an increase in performance stems from the copious amount of active edge sites, the presence of nanoflakes, and high circumferential area exposed by the spheroids. Besides, the electrode with MoS45.1Se11.7P6.1 displays excellent stability in acidic medium over 10 h of continuous operation. This work paves way for improving the catalytic activity of existing Mo‐chalcogenide compounds by doping suitable mixed anions and also reveals the integral role of anions as well as their synergetic effects on the surface physiochemical properties and the HER catalysis. 相似文献
992.
Efficient replacement of nonuniform objects in Web caches 总被引:2,自引:0,他引:2
Cache performance depends heavily on replacement algorithms, which dynamically select a suitable subset of objects for caching in a finite space. Developing such algorithms for wide-area distributed environments is challenging because, unlike traditional paging systems, retrieval costs and object sizes are not necessarily uniform. In a uniform caching environment, a replacement algorithm generally seeks to reduce cache misses, usually by replacing an object with the least likelihood of re-reference. In contrast, reducing total cost incurred due to cache misses is more important in nonuniform caching environments. The authors present the least-unified value algorithm, which performs better than existing algorithms for replacing nonuniform data objects in wide-area distributed environments 相似文献
993.
Within integrated multiple object databases, missing data occurs due to the missing attribute conflict as well as the existence of null values. A set of algorithms is provided in this paper to process the predicates of global queries with missing data. To provide more informative answers to users, the "maybe" results due to missing data are presented in addition to the "certain" results. The local "maybe" results may become "certain" results via the concept of object isomerism. One algorithm is designed based on the centralized approach in which data are forwarded to the same site for integration and processing. Furthermore, to reduce the response time, localized approaches evaluate the predicates within distinct component databases in parallel. The object signature is also applied in the design to further reduce the data transfer. These algorithms are compared and discussed according to the simulation results of both the total execution and response times. Alternately, the global schema may contain multi-valued attributes with values derived from attribute values in different component databases. Hence, the proposed approaches are also extended to process the global queries involving this kind of multi-valued attribute 相似文献
994.
This paper proposes an integrated system for unconstrained face recognition in complex scenes. The scale and orientation tolerant system comprises a face detector followed by a recognizer. Given a color input image of a person, the face detector encloses the face from the complex scene within a circular boundary, and locates the position of the nose. A radial grid mapping centered on the nose is then performed to extract a feature vector within the boundary. The feature vector is input to a radial basis function neural network classifier for face identification. The proposed face detector achieved an average detection rate of 95.8% while the face recognizer achieved an average recognition rate of 97.5% on a database of 21 persons with variations in scale, orientation, natural illumination and background. The two modules were combined to form an automatic face recognition system that was evaluated in the context of a security system using a video database of 21 users and 10 intruders, acquired in an unconstrained environment. A recognition rate of 93.5% with 0% false acceptance rate was achieved. 相似文献
995.
Morphological computation is the concept for which a well-designed hardware can bear part of the computational cost required for robot??s control and perception. So far, many musculoskeletal robots have been developed by taking inspiration from human??s one and shown superior motion performances. The use of pneumatic artificial muscles (PAMs) has been the key to realize these high performance. Additionally, PAMs have the possibility of being used as sensors for environmental information because they are flexible and backdrivable. In this research, we focus on clarifying how PAMs can contribute to morphological computation of robots driven by these actuators. In particular, we propose an analysis method based on transfer entropy and apply this method to the experimental data acquired by a musculoskeletal robot that opens a door. 相似文献
996.
Hyery Kang Yun-Ho Ahn Dong-Yeun Koh Huen Lee 《Korean Journal of Chemical Engineering》2016,33(6):1897-1902
-It has been reported that some aldehyde compounds have formed simple sII clathrate hydrates without help-gas molecules, showing a self-forming effect. However, the structure of aldehyde hydrates is quite unstable due to the “gem-diol reaction”. According to the previous studies, the aldehyde hydrate slowly decomposes at atmospheric condition with the conversion of aldehyde to gem-diol. We investigated binary aldehyde (acetaldehyde, propionaldehyde, and isobutyraldehyde)+methane clathrate hydrate with spectroscopic and thermodynamic analyses. Similar to the simple aldehyde hydrate, the binary hydrates also formed a sII hydrate. During the hydrate formation process, we found that most of the aldehydes converted to gem-diols and were then incorporated into the large cages of the sII hydrate. Depending on the equilibrium constant of the gem-diol reaction caused by the molecular structures of the three aldehydes, different phase equilibrium curves of aldehyde+methane hydrates were obtained. 相似文献
997.
The digital contents market is growing rapidly and we can retrieve digital contents through various multimedia devices including portable hand-held devices, smart phones, and home devices. On the other side, many digital contents without the consent of copyright holders are shared on the Internet. Those copyright infringement problems undermine authoring needs of the digital contents manufacturers and also wither the development of digital contents market. We are sure that we need secure distribution mechanisms for the digital contents supply chain in order to revitalize contents services and markets more and more. Many research projects to limit contents utilization onto legitimate users and to provide secure contents protection and download are in progress. In this paper, we propose a secure D-CAS system (SDCAS) which provides security enhancement to various digital contents downloading services. 相似文献
998.
S.C.L. Koh A. Gunasekaran T. Goodman 《The Journal of Strategic Information Systems》2011,20(4):385-402
This paper reviews existing literature to determine the drivers of and barriers to Enterprise Resource Planning II (ERPII) implementation. The ERPII literature is then extended through interviews with potential players in ERPII implementations to identify the critical success factors (CSFs) or preconditions required for successful implementation throughout supply chains. These interviews were conducted with leading ERP vendors/consultants and organisations involved in the entire supply chain to gather evidence on the success, or lack thereof, of ERPII implementations. The results were compared and contrasted to existing literature on ERPII, collaborative networks, and the extended enterprise. We found more barriers to than drivers of successful ERPII implementation. This leads prospective implementers to have a pessimistic forecast for ERPII implementation success. Our research reveals that main reason for this negativity is a general lack of understanding and appreciation of the capabilities of the extended enterprise network. Second, the research presents two sets of CSFs: CSFs which apply to traditional ERP and carry forward to apply to ERPII, and CSFs that are tailored to the new needs for successful ERPII implementations. Finally, the research questions the suitability of ERPII in today’s modern business environment, and suggests that technology may have overtaken management’s capabilities to capture the full benefits of such an advanced enterprise system. Future trends in ERPII development are also considered in an attempt to find the next phase in the enterprise system life cycle. Beyond ERPII, the research suggests that infrastructure such as large-scale business intelligence (BI) systems must be heavily incorporated into modern enterprise systems to fully understand how information flows throughout an organisation and to make sense of that information. 相似文献
999.
Qi Ying Wong Ning Liu Cheng-Gee Koh Hoi-Yeung Li Wen Siang Lew 《Microfluidics and nanofluidics》2016,20(10):139
Circulating tumour cells (CTC) in the bloodstream has been implicated in cancer metastasis. Efficient removal of CTC could potentially be an effective therapeutic measure against cancer metastasis. In this study, the hydrodynamic focusing flow in microfluidic channels (R e ? 1) was considered together with the magnetophoretic force. The localised magnetic field was achieved through a passivated current-carrying multilayered microstripline, where the generated field gradient was used to attract the magnetic beads to the desired outlet. The experimental results show that the device is capable of isolating purely magnetic beads with an efficiency of 91 % while isolation efficiency of the magnetically tagged HeLa cervical cancer cells from cell suspension yielded an isolation efficiency of 79 %. 相似文献
1000.
Chang-Bun Yoon Young-Hag Koh Gun-Tae Park Hyoun-Ee Kim 《Journal of the American Ceramic Society》2005,88(6):1625-1627
A multilayer ceramic actuator composed of piezoelectrically active Pb(Zn1/3 Nb2/3 )0.2 –Pb(Zr0.5 Ti0.5 )O0.8 (PZN–PZT) layers and electrically conducting PZN–PZT/Ag layers was fabricated by the co-extrusion process. For the piezoelectric layers, PZN–PZT, which is sinterable at a low temperature (900°C), was used. For the conducting layers, a PZN–PZT/Ag composite, made by mixing silver particles with the PZN–PZT matrix, was employed. For the co-extrusion process, piezoelectric and conducting feedrods were made by mixing the PZN–PZT and PZN–PZT/Ag, respectively, with a thermoplastic polymer. The initial feedrods, which were composed of five 3 mm-thick PZN–PZT layers, two 1.5 mm-thick PZN–PZT layers, and six 1 mm-thick PZN–PZT/Ag layers, were co-extruded through a 24 mm × 2 mm reduction die at 105°C to produce continuous multilayered green sheets. The sheets were stacked, warm pressed, and sintered at 900°C for 4 h after binder burnout. The sintered multilayer actuator showed distinct layers without any reaction products or cracks at the interface. The thicknesses of the piezoelectric and conducting layers were about 200 and 70 μm, respectively. The displacement of the multilayer actuator, composed of 40 piezoelectric layers (with a total height of 10.8 mm), was about 10 μm at an applied voltage of 500 V. 相似文献