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991.
下一代移动网络(NGMN)倾向于融合多个无线接入技术(RATs)来为用户提供无处不在的访问服务。而作为一个无处不在系统,能够有一个解决方案来支持日益流行的视频应用程序也是至关重要的。由于移动视频应用程序的高带宽要求和对延迟敏感的特点,如何让移动视频应用程序在不同的RATs之间进行无缝切换并保证服务质量(QoS)是我们面临的一个挑战。为了加快实现在异构网络中提供无缝视频流服务,通过运用IEEE 802.21规定的媒体独立信息服务的服务器提出了一种移动端发起-网络端控制的移动网络切换方案。仿真结果表明,该方案在丢包率、延迟和峰值信噪比等方面提高了性能。 相似文献
992.
针对异构系统中基于多副本机制的容错调度方法忽略调度makespan、任务间依赖与系统链路失效及严格调度方式调度makespan较长问题,首先提出通用调度方式下同时考虑节点和链路失效的可靠性计算方法;然后给出该通用调度问题的0-1整数规划模型;接着提出可靠性意识多副本任务通用调度(RAMD_TGS, reliability-aware multi-duplication task general scheduling)算法,通过遗传算法种群进化来搜索副本映射节点和开始执行时间。实验表明该算法不仅满足可靠性要求,而且与严格调度方式相比能进一步减小调度makespan,该算法资源占用开销也是可接受的。 相似文献
993.
在综合分析各感知网络和以太网网络特点及其异构性的基础上,提出了分层的异构网络融合网关结构模型,设计了网间通信统一的数据包格式和全网统一的地址编码方式.具有多切换接口的M esh终端,能够根据自动切换管理技术智能地接入不同网络.网关实现了基于802.11、802.15和802.3等协议的语音业务、视频图像业务以及数据传输业务在不同网络间的无障碍通信,网关的双向通信功能,使其连通的两端网络以对等方式通信,最终实现了井下全网互联互通. 相似文献
994.
995.
基于网络选择的视频通信带宽博弈算法 总被引:1,自引:0,他引:1
针对异构无线网络的视频通信提出一种基于网络选择的带宽博弈算法(BAG-NS)。该算法首先根据不同用户视频特性及当前网络状况,采用层次分析法和熵值法确定网络评价参数的权重,选择最佳网络;其次构建了基于收益和代价的用户效用函数,通过分布式迭代算法得到其纳什均衡解,并证明了纳什均衡的存在性和唯一性。仿真结果表明,该算法使不同特性的视频用户合理地分布在不同网络,能兼顾用户公平性和网络拥塞控制,增加网络资源利用率,减小用户视频失真,提高用户视频质量。 相似文献
996.
Satoshi Watanabe Tatsumasa Hiratsuka Yusuke Asahi Asumi Tanaka Kazuhiro Mae Minoru T. Miyahara 《Particle & Particle Systems Characterization》2015,32(2):234-242
Gold nanoshells with tunable surface plasmon resonances are a promising material for optical and biomedical applications. They are produced through seed‐mediated growth, in which gold nanoparticles (AuNPs) are seeded on the core particle surface followed by growth of the gold seeds into a shell. However, synthetic gold nanoshell production is typically a multistep, time‐consuming batch‐type process, and a simple and scalable process remains a challenge. In the present study, a continuous flow process for the seed‐mediated growth of silica–gold nanoshells is established by exploiting the excellent mixing performance of a microreactor. In the AuNP‐seeding step, the reduction of gold ions in the presence of core particles in the microreactor enables the one‐step flow synthesis of gold‐decorated silica particles through heterogeneous nucleation. Flow shell growth is also realized using the microreactor by selecting an appropriate reducing agent. Because self‐nucleation in the bulk solution phase is suppressed in the microreactor system, no washing is needed after each step, thus enabling the connection of the microreactors for the seeding and shell growth steps into a sequential flow process to synthesize gold nanoshells. The established system is simple and robust, thus making it a promising technology for producing gold nanoshells in an industrial setting. 相似文献
997.
998.
999.
Tailoring the Optical Absorption of Water‐Stable ZrIV‐ and HfIV‐Based Metal–Organic Framework Photocatalysts
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Tan L. H. Doan Ha L. Nguyen Hung Q. Pham Nguyen‐Nguyen Pham‐Tran Prof. Thach N. Le Kyle E. Cordova 《化学:亚洲杂志》2015,10(12):2660-2668
New ZrIV‐ and HfIV‐based metal–organic framework photocatalysts, termed VNU‐1 and VNU‐2 (where VNU=Vietnam National University), were synthesized and their resulting structures fully characterized. By employing a highly π‐conjugated linker, namely 1,4‐bis(2‐[4‐carboxyphenyl]ethynyl)benzene, the optical absorption properties were effectively red‐shifted into the visible light region. This strategy, coupled with the high water stability of the materials, led to enhanced MOF‐driven photocatalytic degradation, under ultraviolet‐visible light, of organic dye pollutants commonly found in wastewater. 相似文献
1000.
The analysis of two-phase flow in porous media begins with the Stokes equations and an appropriate set of boundary conditions.
Local volume averaging can then be used to produce the well known extension of Darcy's law for two-phase flow. In addition,
a method of closure exists that can be used to predict the individual permeability tensors for each phase. For a heterogeneous
porous medium, the local volume average closure problem becomes exceedingly complex and an alternate theoretical resolution
of the problem is necessary. This is provided by the method of large-scale averaging which is used to average the Darcy-scale
equations over a region that is large compared to the length scale of the heterogeneities.
In this paper we present the derivation of the large-scale averaged continuity and momentum equations, and we develop a method
of closure that can be used to predict the large-scale permeability tensors and the large-scale capillary pressure. The closure
problem is limited by the principle of local mechanical equilibrium. This means that the local fluid distribution is determined by capillary pressure-saturation relations and is not constrained by the solution of an
evolutionary transport equation. Special attention is given to the fact that both fluids can be trapped in regions where the
saturation is equal to the irreducible saturation, in addition to being trapped in regions where the saturation is greater than the irreducible saturation. Theoretical results are given for stratified porous media and a two-dimensional model for a heterogeneous
porous medium. 相似文献