全文获取类型
收费全文 | 339篇 |
免费 | 4篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 53篇 |
金属工艺 | 5篇 |
机械仪表 | 2篇 |
建筑科学 | 11篇 |
能源动力 | 16篇 |
轻工业 | 18篇 |
无线电 | 29篇 |
一般工业技术 | 89篇 |
冶金工业 | 53篇 |
原子能技术 | 1篇 |
自动化技术 | 60篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 13篇 |
2018年 | 9篇 |
2017年 | 14篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 25篇 |
2012年 | 12篇 |
2011年 | 14篇 |
2010年 | 18篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 19篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 16篇 |
1997年 | 14篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有346条查询结果,搜索用时 0 毫秒
1.
Mehra A. Indiresan A. Shin K.G. 《IEEE transactions on pattern analysis and machine intelligence》1997,23(10):616-634
We propose architectural mechanisms for structuring host communication software to provide QoS guarantees. We present and evaluate a QoS sensitive communication subsystem architecture for end hosts that provides real time communication support for generic network hardware. This architecture provides services for managing communication resources for guaranteed QoS (real time) connections, such as admission control, traffic enforcement, buffer management, and CPU and link scheduling. The architecture design is based on three key goals: maintenance of QoS guarantees on a per connection basis, overload protection between established connections, and fairness in delivered performance to best effort traffic. Using this architecture we implement real time channels, a paradigm for real time communication services in packet switched networks. The proposed architecture features a process per channel model that associates a channel handler with each established channel. The model employed for handler execution is one of “cooperative” preemption, where an executing handler yields the CPU to a waiting higher priority handler at well defined preemption points. The architecture provides several configurable policies for protocol processing and overload protection. We present extensions to the admission control procedure for real time channels to account for cooperative preemption and overlap between protocol processing and link transmission at a sending host. We evaluate the implementation to demonstrate the efficacy with which the architecture maintains QoS guarantees on outgoing traffic while adhering to the stated design goals 相似文献
2.
Crystallization kinetics of the Se80–x
Sb
x
Te20 (0x9) alloys have been studied using differential scanning calorimetry. The activation energies for the glass transition and that for crystallization have been determined from the heating rate dependence of the glass transition temperature and the peak crystallization temperature. The results have been analysed using the modified Kissinger's and Matusita's equations for the non-isothermal crystallization of materials. The variation of glass transition temperature with composition suggests that a small amount of Sb ( 4 at %) leads to an increase in the chain length of Se-Te, whereas further increase in Sb atomic per cent increases the number of Se-Te chains in the alloys. 相似文献
3.
Supraglacial debris (SGD) cover on mountain glaciers is known to greatly influence various glacier processes and alter their response to climate change. In this study, vital glacier parameters of five glaciers with varying debris coverage (about 7–26%), located in Zanskar basin, Ladakh Himalaya, were monitored using Landsat imagery (from 1977 to 2013) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global digital elevation model (GDEM). Results reveal how varying amounts of SGD induce categorically distinct responses on glaciers, sharing same geographical settings. The clean glaciers (CG) in the area were found to have higher retreat rates (about 8–19 m year?1), comparable areal shrinkage (about 13–15%), higher accumulation area ratios (AARs) (>0.5), rapid increase in SGD (about 1.6–3.0-fold), and association with increasing numbers of peri- and proglacial lakes (2–8 per glacier). The debris-covered glaciers (DCG) showed minimal frontal changes (about 2–5 m year?1), higher areal shrinkage (about 14–21%), low AARs (<0.5), slow SGD changes (about ≤1.2-fold), and association with increasing numbers of peri- and supraglacial lakes (SGLs) (2–39 per glacier). Moreover, while changes in SGD had a strong negative correlation with changes in glacier area, retreat rates, and AAR, they were positively related with increase in area of SGLs. 相似文献
4.
Mehra A. Xin Zhang Ayon A.A. Waitz I.A. Schmidt M.A. Spadaccini C.M. 《Journal of microelectromechanical systems》2000,9(4):517-527
As part of a program to develop a micro gas turbine engine capable of producing 10-50 W of electrical power in a package less than one cubic centimeter in volume, we present the design, fabrication, packaging, and experimental test results for the 6-wafer combustion system for a silicon microengine. Comprising the main nonrotating functional components of the engine, the device described measures 2.1 cm×2.1 cm×0.38 cm and is largely fabricated by deep reactive ion etching through a total thickness of 3800 μm. Complete with a set of fuel plenums, pressure ports, fuel injectors, igniters, fluidic interconnects, and compressor and turbine static airfoils, this structure is the first demonstration of the complete hot flow path of a multilevel micro gas turbine engine. The 0.195 cm3 combustion chamber is shown to sustain a stable hydrogen flame over a range of operating mass flows and fuel-air mixture ratios and to produce exit gas temperatures in excess of 1600 K. It also serves as the first experimental demonstration of stable hydrocarbon microcombustion within the structural constraints of silicon. Combined with longevity tests at elevated temperatures for tens of hours, these results demonstrate the viability of a silicon-based combustion system for micro heat engine applications 相似文献
5.
The Internet infrastructure must evolve from best-effort service to meet the needs of different customers and applications. With Internet traffic differentiation, service providers can support a range of offerings, such as loss or delay bounds and network bandwidth allocation, to meet different performance requirements. The differentiated services (Diffserv) architecture provides a scalable approach, in which network access (or edge) devices aggregate traffic flows onto provisioned pipes that traverse a streamlined network core. We have identified the key requirements for provisioning Diffserv functions on Internet servers. Based on these requirements, we have implemented, and deployed, a policy-based architecture on IBM's AIX operating system that provides Diffserv services to both QoS-aware and -unaware applications 相似文献
6.
Harsh Bhatt Nilesh Kumar Jadav Aparna Kumari Rajesh Gupta Sudeep Tanwar Zdzislaw Polkowski Amr Tolba Azza S. Hassanein 《Concurrency and Computation》2024,36(3):e7911
In recent years, smart healthcare, artificial intelligence (AI)-aided diagnostics, and automated surgical robots are just a few of the innovations that have emerged and gained popularity with the advent of Healthcare 4.0. Such technologies are powered by machine learning (ML) and deep learning (DL), which are preferable for disease diagnosis, identifying patterns, prescribing treatments, and forecasting diseases like stroke prediction, cancer prediction and so forth. Nevertheless, much data is needed for AI, ML, and DL-based systems to train effectively and provide the desired outcomes. Further, it raises concerns about data privacy, security, communication overhead, regulatory compliance and so forth. Federated learning (FL) is a technology that protects data security and privacy by limiting data sharing and utilizing model information of distributed systems to enhance performance. However, existing approaches are traditionally verified on pre-established datasets that fail to capture real-life applicability. Therefore, this study proposes an AI-enabled stroke prediction architecture consisting of FL based on the artificial neural network (ANN) model using data from actual stroke cases. This architecture can be implemented on healthcare-based wearable devices (WD) for real-time use as it is effective, precise, and computationally affordable. In order to continuously enhance the performance of the global model, the proposed FL-based architecture aggregates the optimizer weights of many clients using a fifth-generation (5G) communication channel. Then, the performance of the proposed FL-based architecture is studied based on multiple parameters such as accuracy, precision, recall, bit error rate, and spectral noise. It outperforms the traditional approaches regarding accuracy, which is 5% to 10% higher. 相似文献
7.
Hasan T. Karaoglu Aparna Gupta Murat Yuksel Weini Liu Koushik Kar 《Computer Communications》2013,36(17-18):1708-1725
Despite the huge success of the Internet in providing basic communication services, its economic architecture needs to be upgraded so as to provide end-to-end guaranteed or more reliable services to its customers. Currently, a user or an enterprise that needs end-to-end bandwidth guarantees between two arbitrary points in the Internet for a short period of time has no way of expressing its needs. To allow these much needed basic services, we propose a single-domain edge-to-edge (g2g) dynamic capacity contracting mechanism, where a network customer can enter into a bandwidth contract on a g2g path at a future time, at a predetermined price. For practical and economic viability, such forward contracts must involve a bailout option to account for bandwidth becoming unavailable at service delivery time, and must be priced appropriately to enable Internet Service Providers (ISPs) manage risks in their contracting and investments. Our design allows ISPs to advertise point-to-point different prices for each of their g2g paths instead of the current point-to-anywhere prices, allowing discovery of better end-to-end paths, temporal flexibility and efficiency of bandwidth usage. We compute the risk-neutral prices for these g2g bailout forward contracts (BFCs), taking into account correlations between different contracts due to correlated demand patterns and overlapping paths. We apply this multiple g2g BFC framework on network models with Rocketfuel topologies. We evaluate our contracting mechanism in terms of key network performance metrics like fraction of bailouts, revenue earned by the provider, and adaptability to link failures. We also explore the tradeoffs between complexity of pricing and performance benefits of our BFC mechanism. 相似文献
8.
Asok Aparna A. S Sethulekshmi Jitha S. Jayan Appukuttan Saritha Kuruvilla Joseph 《大分子材料与工程》2021,306(11):2100429
Boron nitride (BN) is an eminent inorganic compound having many interesting characteristics such as improved oxidation resistance, mechanical strength, good thermal conductivity (TC), higher bandgap, high chemical stability, thermal stability, high hydrophobicity, and electrical insulation. The use of BN as a filler in polymers is a well-established strategy to tailor the properties of polymer composites. Recent studies depict an interesting urge to reap the synergistic effect of various nanofillers with BN in the form of hybrids. Hence the consolidation of the works on BN based hybrid fillers would definitely attract researchers so that these new filler systems could be transformed into useful polymer nanocomposites in future. This review article focuses on the synthesis and characterization of various boron nitride based hybrids in detail. Moreover, the review also throws light on different BN hybrid reinforced polymer nanocomposites (PNCs) and their thermal, electrical, electronic as well as biomedical applications in a detailed manner. Thus the review anticipates serving as a tool toward understanding the recent trends in the field of boron nitride hybrid based ternary polymer composites. 相似文献
9.
Santosh Shivaji Biranje Abhinav Nathany Neha Mehra Ravindra Adivarekar 《Journal of surfactants and detergents》2015,18(6):949-956
Artificially soiled test fabrics are widely used to study the cleaning performance of detergents formulations. In this study, artificial soiled cotton test fabrics were prepared in the laboratory using carbon black as a model soil. Design of experiments was used to optimise the concentration of detergent ingredients for stain removal. A multi‐factorial analysis of variance was used to model the effect of sodium dodecylbenzene sulfonate, nonylphenol ethoxylate, sodium silicate, sodium citrate and sodium carbonate as builders on soil removal. A colourimetric evaluation using the CIELAB system was used to measure soil removal. In general, performance increases with increasing concentration of surfactant, silicate and soda ash. 相似文献
10.
Tetragonal ( t ) ZrO2 nanoparticles have been obtained by a partial Eu3+ →Zr4+ substitution, synthesized using a simple oxalate method at a moderate temperature of 650°C in air. The Eu3+ additive, 2 mol% used according to the optimal photoluminescence (PL), gives small crystallites of the sample. On raising the temperature further, the average crystallite size D grows slowly from 16 nm to a value as big as 49 nm at 1200°C. The Eu3+ : t -ZrO2 nanoparticles have a wide PL spectrum at room temperature in the visible to near-IR regions (550–730 nm) in the 5 D0 →7 FJ (Eu3+ ), J =1–4, electronic transitions. The intensity of the 5 D0 →7 F4 group is as large as that of the characteristic 5 D0 →7 F2 group of the spectrum in the forced electric-dipole allowed transitions. The enhanced t -ZrO2 phase stability and wide PL can be attributed to the combined effects of an amorphous Eu3+ -rich surface and part of the Eu3+ doping of ZrO2 of small crystallites. 相似文献