全文获取类型
收费全文 | 56666篇 |
免费 | 7768篇 |
国内免费 | 5822篇 |
专业分类
电工技术 | 4958篇 |
技术理论 | 1篇 |
综合类 | 6906篇 |
化学工业 | 4933篇 |
金属工艺 | 4302篇 |
机械仪表 | 5037篇 |
建筑科学 | 6462篇 |
矿业工程 | 2632篇 |
能源动力 | 1565篇 |
轻工业 | 1141篇 |
水利工程 | 2063篇 |
石油天然气 | 4140篇 |
武器工业 | 1122篇 |
无线电 | 3677篇 |
一般工业技术 | 8803篇 |
冶金工业 | 1907篇 |
原子能技术 | 299篇 |
自动化技术 | 10308篇 |
出版年
2024年 | 348篇 |
2023年 | 947篇 |
2022年 | 1706篇 |
2021年 | 1911篇 |
2020年 | 2104篇 |
2019年 | 1762篇 |
2018年 | 1813篇 |
2017年 | 2168篇 |
2016年 | 2442篇 |
2015年 | 2520篇 |
2014年 | 3382篇 |
2013年 | 3527篇 |
2012年 | 4398篇 |
2011年 | 4389篇 |
2010年 | 3434篇 |
2009年 | 3459篇 |
2008年 | 3381篇 |
2007年 | 3977篇 |
2006年 | 3535篇 |
2005年 | 3021篇 |
2004年 | 2406篇 |
2003年 | 2083篇 |
2002年 | 1783篇 |
2001年 | 1582篇 |
2000年 | 1407篇 |
1999年 | 1145篇 |
1998年 | 977篇 |
1997年 | 887篇 |
1996年 | 692篇 |
1995年 | 597篇 |
1994年 | 504篇 |
1993年 | 383篇 |
1992年 | 311篇 |
1991年 | 272篇 |
1990年 | 278篇 |
1989年 | 229篇 |
1988年 | 128篇 |
1987年 | 66篇 |
1986年 | 44篇 |
1985年 | 42篇 |
1984年 | 46篇 |
1983年 | 40篇 |
1982年 | 34篇 |
1981年 | 11篇 |
1980年 | 29篇 |
1979年 | 24篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1959年 | 5篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
973.
动态节点质心定位改进算法 总被引:1,自引:0,他引:1
为降低无线传感器网络的定位误差,提高动态节点的定位精度和定位覆盖度,使节点定位能够应用于动态环境下,基于传统的定位算法,提出了一种新的动态节点定位改进算法。该算法通过未知节点接收、保存的分组信息来循环组成虚拟三角形,同时依靠内点测试方法来判断未知节点自身位置,最后根据质心算法来进行最终定位。将仿真结果与传统算法进行比较,结果表明,改进算法可以大大提高无线传感器网络的定位精度和覆盖度。 相似文献
974.
975.
976.
977.
Xiangdong Yuelong Songqiao Xiaoli 《Journal of Parallel and Distributed Computing》2009,69(10):866-876
This paper presents DMVOCC-2PLV (Distributed Multiversion Optimistic Concurrency Control with Two-Phase Local Validation) protocol for processing mobile distributed real-time transactions in mobile broadcast environments. In DMVOCC-2PLV protocol, transaction validation is performed at two levels: local validation and global validation. Local validation of transactions is performed in two phases: local pre-validation and local final validation. At the MHs (Mobile Hosts), all mobile transactions perform local pre-validation of transactions by using a backward validation mechanism. The local pre-validation process is carried out against committed transactions at the server in the last broadcast cycle. Such an early data conflict detection feature can save processing and communication resources. Transactions that survive in local pre-validation must be submitted to the server for local final validation. In global validation distributed update transactions have to check to ensure distributed serializability in all participants. The protocol can eliminate conflicts between mobile read-only and mobile update transactions, and resolve data conflicts flexibly using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly reduced. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. The results of simulation experiment show that the new protocol proposed offers better performance in terms of miss rate, restart rate, commit rate and throughput. 相似文献
978.
DMM:A dynamic memory mapping model for virtual machines 总被引:2,自引:0,他引:2
CHEN HaoGang WANG XiaoLin WANG ZhenLin ZHANG BinBin LUO YingWei & LI XiaoMing 《中国科学:信息科学(英文版)》2010,(6):1097-1108
Memory virtualization is an important part in the design of virtual machine monitors(VMM).In this paper,we proposed dynamic memory mapping(DMM) model,a mechanism that allows the VMM to change the mapping between a virtual machine's physical memory and the underlying hardware resource while the virtual machine is running.By utilizing DMM,the VMM can implement many novel memory management policies,such as Demand Paging,Swapping,Ballooning,Memory Sharing and Copy-On-Write,while preserving compatibility with va... 相似文献
979.
Iterative Learning Control for uncertain systems: Robust monotonic convergence analysis 总被引:1,自引:0,他引:1
Jeroen van de Wijdeven Author Vitae Author Vitae Okko Bosgra Author Vitae 《Automatica》2009,45(10):2383-1666
In this paper, we present a novel Robust Monotonic Convergence (RMC) analysis approach for finite time interval Iterative Learning Control (ILC) for uncertain systems. For that purpose, a finite time interval model for uncertain systems is introduced. This model is subsequently used in an RMC analysis based on μ analysis. As a result, we can handle additive and multiplicative uncertainty models in the RMC problem formulation, analyze RMC of linear time invariant MIMO systems controlled by any linear trial invariant ILC controller, and formulate additional straightforward RMC conditions for ILC controlled systems. To illustrate the derived results, we analyze the RMC properties of linear quadratic (LQ) norm optimal ILC. 相似文献
980.
Virtual execution environments, such as the Java virtual machine, promote platform‐independent software development. However, when it comes to analyzing algorithm complexity and performance bottlenecks, available tools focus on platform‐specific metrics, such as the CPU time consumption on a particular system. Other drawbacks of many prevailing profiling tools are high overhead, significant measurement perturbation, as well as reduced portability of profiling tools, which are often implemented in platform‐dependent native code. This article presents a novel profiling approach, which is entirely based on program transformation techniques, in order to build a profiling data structure that provides calling‐context‐sensitive program execution statistics. We explore the use of platform‐independent profiling metrics in order to make the instrumentation entirely portable and to generate reproducible profiles. We implemented these ideas within a Java‐based profiling tool called JP. A significant novelty is that this tool achieves complete bytecode coverage by statically instrumenting the core runtime libraries and dynamically instrumenting the rest of the code. JP provides a small and flexible API to write customized profiling agents in pure Java, which are periodically activated to process the collected profiling information. Performance measurements point out that, despite the presence of dynamic instrumentation, JP causes significantly less overhead than a prevailing tool for the profiling of Java code. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献