全文获取类型
收费全文 | 602篇 |
免费 | 29篇 |
国内免费 | 12篇 |
专业分类
化学 | 385篇 |
晶体学 | 6篇 |
力学 | 8篇 |
数学 | 92篇 |
物理学 | 83篇 |
无线电 | 69篇 |
出版年
2023年 | 7篇 |
2022年 | 3篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 20篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 41篇 |
2012年 | 47篇 |
2011年 | 52篇 |
2010年 | 24篇 |
2009年 | 22篇 |
2008年 | 40篇 |
2007年 | 37篇 |
2006年 | 27篇 |
2005年 | 37篇 |
2004年 | 31篇 |
2003年 | 37篇 |
2002年 | 16篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 11篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1969年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有643条查询结果,搜索用时 15 毫秒
91.
Copping R Gaunt AJ May I Sharrad CA Collison D Helliwell M Fox OD Jones CJ 《Chemical communications (Cambridge, England)》2006,(36):3788-3790
(NH4)14Na4[(Np3W4O15)(H2O)3(BiW9O33)3].62H2O (1) and (NH4)14.5Na3.5[(Np3W4O15)(H2O)3(SbW9O33)3].40.5H2O (2) each contain three neptunyl(v) moieties encapsulated within heteropolyoxotungstate frameworks in which axial {NpO2}+ oxygens form one face of a WO6 octahedron. 相似文献
92.
Benjamin M. O’Brien Emilio P. Calius Tokushu Inamura Sheng Q. Xie Iain A. Anderson 《Applied Physics A: Materials Science & Processing》2010,100(2):385-389
Some of the most exciting possibilities for dielectric elastomer artificial muscles consist of biologically inspired networks
of smart actuators working towards common goals. However, the creation of these networks will only be realised once intelligence
and feedback can be fully distributed throughout an artificial muscle device. Here we show that dielectric elastomer artificial
muscles can be built with intrinsic sensor, control, and driver circuitry, bringing them closer in capability to their natural
analogues. This was achieved by exploiting the piezoresistive behaviour of the actuator’s highly compliant electrodes using
what we have called the dielectric elastomer switch. We developed suitable switching material using carbon loaded silicone
grease and experimentally demonstrated the primitives required for self-sensing actuators and digital computation, namely
compliant electromechanical NAND gates and oscillator circuits. We anticipate that dielectric elastomer switches will reduce
the need for bulky and rigid external circuitry as well as provide the simple distributed intelligence required for soft,
biologically inspired networks of actuators. Examples include many-degree-of-freedom robotic hearts, intestines, and manipulators;
wearable assistive devices; smart sensor skins and fabrics; and ultimately new types of artificial muscle embedded, electromechanical
computers. 相似文献
93.
Ren P. Liu Zvi Rosberg Iain B. Collings Carol Wilson Alex Y. Dong Sanjay Jha 《International Journal of Wireless Information Networks》2009,16(3):131-141
Field measurements reveal that radio link asymmetry has a severe impact on reliable data delivery. We analyze the energy efficiencies
of selected reliability schemes for asymmetric radio links using theoretical models. The analysis provides guidelines for
retransmission control so as to balance between reliability and energy consumption. We also design two enhancements to the
“implicit” ARQ scheme addressing the negative effects of asymmetric radio links. The energy efficiencies of these algorithms
are explicitly derived using our theoretical model and validated by simulations and field trials. Based on the analysis of
the two enhanced algorithms, we propose an improvement, referred to as Energy Efficient Reliable Data Collection (EERDC) that controls the retransmissions of the enhanced ARQ schemes. Simulations and field trials confirm our theoretical
findings and demonstrate that our proposed EERDC algorithm alleviates the impact of link asymmetry and achieves energy savings.
Ren P. Liu joined CSIRO in 1995 after finishing his Ph.D. at the University of Newcastle, Australia. He has been heavily involved in a number of commercial projects delivering solutions to a variety of customers such as Optus, AARNet, Nortel, Queensland Health, CityRail, and Rio Tinto. He is currently a principal research scientist of networking technologies in CSIRO ICT Centre. His interests include internetworking design, wireless network modelling and performance evaluation. Zvi Rosberg has joined CSIRO, ICT centre in 2007 as the science leader of networking research. Previously, he held positions in the Academia and in the industry where he has been engaged in basic research and development in communication networks, wireless resource allocation and various Internet technologies. While he was with the IBM Research Lab, he won three IBM outstanding technical achievement awards, one of which is for an IBM licensed networking product. While he was the chief scientist of Radware Ltd., he designed and led the development of a content delivery network. He is serving on the editorial board of the Wireless Networks (WINET) and the International Journal of Communication Systems (IJCS). His research interest include traffic engineering, wireless resource allocation, transmitter power control and planning of cellular networks, routing and scheduling, optical and ultra high speed networks, Internet congestion and flow control, applied probability and analysis of network systems. Iain B. Collings received the B.E. degree in Electrical and Electronic Engineering from the University of Melbourne in 1992, and the Ph.D. degree in Systems Engineering from the Australian National University in 1995. Currently he is a CEO Science Leader at the Australian CSIRO, working in the Wireless Technologies Laboratory, ICT Centre. Prior to this he was an Associate Professor at the University of Sydney (1999–2005); a Lecturer at the University of Melbourne (1996–1999); and a Research Fellow in the Australian Cooperative Research Centre for Sensor Signal and Information Processing (1995). He has published over 160 research papers in the area of mobile digital communications. More specifically, channel estimation and adaptive multi-carrier modulation, for time-varying, multi-user, and MIMO channels. Dr. Collings currently serves as an Editor for the IEEE Transactions on Wireless Communications (since 2002), and for the Elsevier Physical Communication Journal PHYCOM (since 2007). He has served as the Vice Chair of the Technical Program Committee for IEEE Wireless Communications and Networking Conference (WCNC) 2010 and IEEE Vehicular Technology Conf. (VTC) Spring 2006, as well as serving on a number of other TPCs and organizing committees of IEEE conferences. He is a founding organizer of the Australian Communication Theory Workshops 2000–2009. He is also the Chair of the IEEE NSW Section Joint Communications & Signal Processing Chapter. Carol Wilson received a BSEE in 1983 and MSEE in 1983 from Virginia Tech. She is a research consultant on propagation and spectrum management for CSIRO and is currently working on Radio Quiet Zone issues for next generation radioastronomy. She is Vice-Chairman of ITU-R Study Group 3 (Radiowave Propagation) and Chairman of ITU-R Working Party 3M (Point-to-point and Earth-space propagation). Alex Y. Dong is a Ph.D. candidate in School of Computer Science and Engineering, University of New South Wales. His current research interest is context sensing in Participatory Wireless Sensor Networks (PWSN). Sanjay Jha is a Professor and Head of the Network Group at the School of Computer Science and Engineering at the University of New South Wales. He holds a Ph.D. degree from the University of Technology, Sydney, Australia. His research activities cover a wide range of topics in networking including Wireless Sensor Networks, Adhoc/Community wireless networks, Resilience/Quality of Service (QoS) in IP Networks, and Active/Programmable network. Sanjay has published over 100 articles in high quality journals and conferences. He is the principal author of the book Engineering Internet QoS and a co-editor of the book Wireless Sensor Networks: A Systems Perspective. He is an associate editor of the IEEE Transactions on Mobile computing. He was a Member-at-Large, Technical Committee on Computer Communications (TCCC), IEEE Computer Society for a number of years. He has served on program committees of several conferences. He was the Technical Program Committee of IEEE Local Computer Networks-LCN2004 and ATNAC04 conferences, and co-chair and general chair of the Emnets-1 and Emnets-II workshop respectively. Sanjay was also the General Chair of ACM Sensys 2007 symposium. 相似文献
Sanjay JhaEmail: |
Ren P. Liu joined CSIRO in 1995 after finishing his Ph.D. at the University of Newcastle, Australia. He has been heavily involved in a number of commercial projects delivering solutions to a variety of customers such as Optus, AARNet, Nortel, Queensland Health, CityRail, and Rio Tinto. He is currently a principal research scientist of networking technologies in CSIRO ICT Centre. His interests include internetworking design, wireless network modelling and performance evaluation. Zvi Rosberg has joined CSIRO, ICT centre in 2007 as the science leader of networking research. Previously, he held positions in the Academia and in the industry where he has been engaged in basic research and development in communication networks, wireless resource allocation and various Internet technologies. While he was with the IBM Research Lab, he won three IBM outstanding technical achievement awards, one of which is for an IBM licensed networking product. While he was the chief scientist of Radware Ltd., he designed and led the development of a content delivery network. He is serving on the editorial board of the Wireless Networks (WINET) and the International Journal of Communication Systems (IJCS). His research interest include traffic engineering, wireless resource allocation, transmitter power control and planning of cellular networks, routing and scheduling, optical and ultra high speed networks, Internet congestion and flow control, applied probability and analysis of network systems. Iain B. Collings received the B.E. degree in Electrical and Electronic Engineering from the University of Melbourne in 1992, and the Ph.D. degree in Systems Engineering from the Australian National University in 1995. Currently he is a CEO Science Leader at the Australian CSIRO, working in the Wireless Technologies Laboratory, ICT Centre. Prior to this he was an Associate Professor at the University of Sydney (1999–2005); a Lecturer at the University of Melbourne (1996–1999); and a Research Fellow in the Australian Cooperative Research Centre for Sensor Signal and Information Processing (1995). He has published over 160 research papers in the area of mobile digital communications. More specifically, channel estimation and adaptive multi-carrier modulation, for time-varying, multi-user, and MIMO channels. Dr. Collings currently serves as an Editor for the IEEE Transactions on Wireless Communications (since 2002), and for the Elsevier Physical Communication Journal PHYCOM (since 2007). He has served as the Vice Chair of the Technical Program Committee for IEEE Wireless Communications and Networking Conference (WCNC) 2010 and IEEE Vehicular Technology Conf. (VTC) Spring 2006, as well as serving on a number of other TPCs and organizing committees of IEEE conferences. He is a founding organizer of the Australian Communication Theory Workshops 2000–2009. He is also the Chair of the IEEE NSW Section Joint Communications & Signal Processing Chapter. Carol Wilson received a BSEE in 1983 and MSEE in 1983 from Virginia Tech. She is a research consultant on propagation and spectrum management for CSIRO and is currently working on Radio Quiet Zone issues for next generation radioastronomy. She is Vice-Chairman of ITU-R Study Group 3 (Radiowave Propagation) and Chairman of ITU-R Working Party 3M (Point-to-point and Earth-space propagation). Alex Y. Dong is a Ph.D. candidate in School of Computer Science and Engineering, University of New South Wales. His current research interest is context sensing in Participatory Wireless Sensor Networks (PWSN). Sanjay Jha is a Professor and Head of the Network Group at the School of Computer Science and Engineering at the University of New South Wales. He holds a Ph.D. degree from the University of Technology, Sydney, Australia. His research activities cover a wide range of topics in networking including Wireless Sensor Networks, Adhoc/Community wireless networks, Resilience/Quality of Service (QoS) in IP Networks, and Active/Programmable network. Sanjay has published over 100 articles in high quality journals and conferences. He is the principal author of the book Engineering Internet QoS and a co-editor of the book Wireless Sensor Networks: A Systems Perspective. He is an associate editor of the IEEE Transactions on Mobile computing. He was a Member-at-Large, Technical Committee on Computer Communications (TCCC), IEEE Computer Society for a number of years. He has served on program committees of several conferences. He was the Technical Program Committee of IEEE Local Computer Networks-LCN2004 and ATNAC04 conferences, and co-chair and general chair of the Emnets-1 and Emnets-II workshop respectively. Sanjay was also the General Chair of ACM Sensys 2007 symposium. 相似文献
94.
A. C. Mayer Michael F. Toney Shawn R. Scully Jonathan Rivnay Christoph J. Brabec Marcus Scharber Marcus Koppe Martin Heeney Iain McCulloch Michael D. McGehee 《Advanced functional materials》2009,19(8):1173-1179
The performance of polymer:fullerene bulk heterojunction solar cells is heavily influenced by the interpenetrating nanostructure formed by the two semiconductors because the size of the phases, the nature of the interface, and molecular packing affect exciton dissociation, recombination, and charge transport. Here, X‐ray diffraction is used to demonstrate the formation of stable, well‐ordered bimolecular crystals of fullerene intercalated between the side‐chains of the semiconducting polymer poly(2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene. It is shown that fullerene intercalation is general and is likely to occur in blends with both amorphous and semicrystalline polymers when there is enough free volume between the side‐chains to accommodate the fullerene molecule. These findings offer explanations for why luminescence is completely quenched in crystals much larger than exciton diffusion lengths, how the hole mobility of poly(2‐methoxy‐5‐(3′,7′‐dimethyloxy)‐p‐phylene vinylene) increases by over 2 orders of magnitude when blended with fullerene derivatives, and why large‐scale phase separation occurs in some polymer:fullerene blend ratios while thermodynamically stable mixing on the molecular scale occurs for others. Furthermore, it is shown that intercalation of fullerenes between side chains mostly determines the optimum polymer:fullerene blending ratios. These discoveries suggest a method of intentionally designing bimolecular crystals and tuning their properties to create novel materials for photovoltaic and other applications. 相似文献
95.
Abstract The stability of travelling waves which occur when a nematic liquid crystal is subjected to crossed electric and magnetic fields has been studied previously where conditions on a control parameter q for stability to occur have been given. This article is concerned with the behaviour of the stable perturbations as time increases. For each of the three travelling wave solutions we can determine the long-term monotonic or oscillatory behaviour of the perturbations using knowledge of the spectrum of the operator governing the perturbation equation. 相似文献
96.
Simon J. Illingworth Iain C. Waugh Matthew P. Juniper 《Proceedings of the Combustion Institute》2013,34(1):911-920
This paper examines nonlinear thermoacoustic oscillations of a ducted Burke-Schumann diffusion flame. The nonlinear dynamics of the thermoacoustic system are studied using two distinct approaches. In the first approach, a continuation analysis is performed to find limit cycle amplitudes over a range of operating conditions. The strength of this approach is that one can characterize the coupled system’s nonlinear behaviour over a large parameter space with relative ease. It is not able to give physical insight into that behaviour, however. The second approach uses a Flame Describing Function (FDF) to characterize the flame’s response to harmonic velocity fluctuations over a range of forcing frequencies and forcing amplitudes, from which limit cycle amplitudes can be found. A strength of the FDF approach is that it reveals the physical mechanisms responsible for the behaviour observed. However, the calculation of the FDF is time consuming, and it must be recalculated if the flame’s operating conditions change. With the strengths and shortcomings of the two approaches in mind, this paper advocates combining the two to provide the dynamics over a large parameter space and, furthermore, physical insight into that behaviour at judiciously-chosen points in the parameter space. Further physical insight concerning the flame’s near-linear response at all forcing amplitudes is given by studying the forced flame in the time domain. It is shown that, for this flame model, the limit cycles arise because of the flame’s nonlinear behaviour when it is close to the inlet. 相似文献
97.
Takaaki Takatsuka Hideki Tomita Tetsu Sonoda Volker Sonnenschein Chika Sakamoto Hiroki Mita Takuma Noto Chikara Ito Shigetaka Maeda Tetsuo Iguchi Michiharu Wada Klaus Wendt Iain Moore 《Hyperfine Interactions》2013,216(1-3):41-46
93Nb(n, n′)93mNb reaction allows retrospective estimation of integrated fast neutron dose in nuclear reactor. We proposed isomer-selective trace analysis of 93mNb by Resonance Ionization Mass Spectrometry (RIMS) combined with a gas-jet atomic source and an injection locked Ti:Sapphire laser system operated at several kHz. Resonant ionization spectroscopy of Nb in gas-jet using Ti:Sapphire laser was demonstrated. 相似文献
98.
It is well known that a plane graph is Eulerian if and only if its geometric dual is bipartite. We extend this result to partial duals of plane graphs. We then characterize all bipartite partial duals of a plane graph in terms of oriented circuits in its medial graph. 相似文献
99.
1-Methyl-3,4-dihydroquinoxalin-2(1H)-one was heated with a range of aldehydes to generate intermediate azomethine ylides which underwent [3 + 2] cycloaddition reactions with N-methyl or N-phenylmaleimide to give substituted tetrahydropyrroloquinoxalinones. Only one (racemic) stereoisomer was formed in each case and the stereochemical outcome was verified by single crystal X-ray analysis. The products from this multicomponent reaction could be oxidised with DDQ to the pyrroloquinoxalinones. 相似文献
100.
A short-distance heavy-quark mass depends on two parameters: the renormalization scale mu and a scale R controlling the absorption of infrared fluctuations. The radius for perturbative corrections that build up the mass beyond its pointlike definition in the pole scheme is approximately 1/R. Treating R as a variable gives a renormalization-group equation. R evolution improves the stability of conversion between short-distance mass schemes, allowing us to avoid large logs and the renormalon. R evolution can also be used to study IR renormalons without using bubble chains, yielding a convergent sum rule for the coefficient of the O(Lambda(QCD)) renormalon ambiguity of the pole mass. 相似文献