全文获取类型
收费全文 | 196560篇 |
免费 | 17500篇 |
国内免费 | 10535篇 |
专业分类
电工技术 | 15499篇 |
技术理论 | 24篇 |
综合类 | 18792篇 |
化学工业 | 22256篇 |
金属工艺 | 9667篇 |
机械仪表 | 13311篇 |
建筑科学 | 19927篇 |
矿业工程 | 7712篇 |
能源动力 | 6531篇 |
轻工业 | 11631篇 |
水利工程 | 6960篇 |
石油天然气 | 7283篇 |
武器工业 | 1674篇 |
无线电 | 13555篇 |
一般工业技术 | 14840篇 |
冶金工业 | 12486篇 |
原子能技术 | 1149篇 |
自动化技术 | 41298篇 |
出版年
2024年 | 954篇 |
2023年 | 2695篇 |
2022年 | 4897篇 |
2021年 | 5736篇 |
2020年 | 6419篇 |
2019年 | 5031篇 |
2018年 | 4517篇 |
2017年 | 5798篇 |
2016年 | 6709篇 |
2015年 | 7378篇 |
2014年 | 14428篇 |
2013年 | 13211篇 |
2012年 | 14971篇 |
2011年 | 15650篇 |
2010年 | 11411篇 |
2009年 | 12053篇 |
2008年 | 11087篇 |
2007年 | 13447篇 |
2006年 | 11937篇 |
2005年 | 10045篇 |
2004年 | 8576篇 |
2003年 | 7435篇 |
2002年 | 6166篇 |
2001年 | 4910篇 |
2000年 | 4002篇 |
1999年 | 3080篇 |
1998年 | 2381篇 |
1997年 | 1873篇 |
1996年 | 1607篇 |
1995年 | 1307篇 |
1994年 | 1060篇 |
1993年 | 740篇 |
1992年 | 603篇 |
1991年 | 491篇 |
1990年 | 347篇 |
1989年 | 331篇 |
1988年 | 240篇 |
1987年 | 126篇 |
1986年 | 147篇 |
1985年 | 123篇 |
1984年 | 128篇 |
1983年 | 130篇 |
1982年 | 59篇 |
1981年 | 41篇 |
1980年 | 49篇 |
1979年 | 39篇 |
1978年 | 15篇 |
1977年 | 33篇 |
1959年 | 21篇 |
1951年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
简要介绍No.7信令监测系统的技术现状、发展前景及应用情况,阐述了No.7信令监测系统在公众电话网(国际国内电话网/智能网等)的网络维护管理工可以发挥的强大功能和多种应用。 相似文献
992.
传输网管技术的现状及展望 总被引:1,自引:0,他引:1
本文从接口标准化、接口提供、网管系统开发实施等方面,全面分析了传输网管技术的发展现状,并对存在的困难及其出路做了探讨和展望。 相似文献
993.
A fast intra skip detection algorithm based on the rate‐distortion (RD) cost for an inter frame (P‐slices) is proposed for H.264/AVC video encoding. In the H.264/AVC coding standard, a robust rate‐distortion optimization technique is used to select the best coding mode and reference frame for each macroblock (MB). There are three types of intra predictions according to profiles. These are 16×16 and 4×4 intra predictions for luminance and an 8×8 intra prediction for chroma. For the high profile, an 8×8 intra prediction has been added for luminance. The 4×4 prediction mode has 9 prediction directions with 4 directions for 16×16 and 8×8 luma, and 8×8 chrominance. In addition to the inter mode search procedure, an intra mode search causes a significant increase in the complexity and computational load for an inter frame. To reduce the computational load of the intra mode search at the inter frame, the RD costs of the neighborhood MBs for the current MB are used and we propose an adaptive thresholding scheme for the intra skip extraction. We verified the performance of the proposed scheme through comparative analysis of experimental results using joint model reference software. The overall encoding time was reduced up to 32% for the IPPP sequence type and 35% for the IBBPBBP sequence type. 相似文献
994.
995.
Among the various issues lying in optical burst switching (OBS) networks, burstification, i.e., assembling multiple IP packets
into bursts, is an important one. Between the two important aspects related to burst assembly, the burst assembly algorithm
aspect has been extensively studied in the literature. However, as far as we know, there is no research about the burstification
queue management (BQM) aspect, which refers to how many burstification queues (BQ) we should set at each OBS edge node and
how to manage these BQs. Suppose there are G destinations (egress edge nodes) and the OBS network provides S different quality of service (QoS) classes. Traditionally, it is simply regarded that each ingress edge node needs G· S queues to sort incoming packets, one for each possible destination and QoS class. For simplicity, we call this policy the
static dedicate BQM (SDB) policy. The SDB policy, though simple, lacks scalability since we have to add S BQs at each OBS
edge node if an extra OBS edge node is added to the OBS network. To solve this problem, we propose in this paper two BQM policies:
quasi-static BQM (QSB) policy and dynamic BQM (DB) policy. For the QSB policy, we derive the packet loss probability due to
lacking BQs based on a Markov chain, from which we can work out the employed number of BQs for a given packet loss probability.
Based on these results, the scalability of the QSB policy is also studied. With the DB policy, we not only can dynamically
assign BQs for incoming packets, but also can dynamically allocate buffer capacity for each BQ by using a least-mean-square
(LMS)-based linear prediction filter. The performance of the DB policy is investigated by analysis and extensive simulations.
We also compared the performance of the QSB policy and the DB policy. Results from analysis and simulation demonstrate that
the DB policy is the best. 相似文献
996.
Saravut Charcranoon Tarek S. El-Bawab Jong-Dug Shin Hakki C. Cankaya 《Photonic Network Communications》2006,11(1):99-110
We propose a new burst scheduling mechanism for Optical Burst-Switched (OBS) networks. The new approach is made possible by
gathering data bursts into groups and performing the scheduling decision for each group collectively. In OBS group-scheduling,
bursts will not be considered for scheduling until a pre-defined time period elapses, during which the group of burst header
packets would be gathered. By transforming a set of data bursts into a set of corresponding time intervals, the problem of
scheduling these bursts is transformed into a combinatorial optimization problem. Graph algorithms are applied to obtain the
maximum number of non-overlapping bursts. The proposed OBS group-scheduling scheme is shown to improve the performance of
OBS networks over existing scheduling schemes in terms of burst loss probability and channel utilization. With an extension
through a sequential optimization, using a Branch-and-Bound technique, the proposed scheme can support multiple classes of
service. It is shown that the new scheduling approach has several desired characteristics including fairness and service differentiability
among classes in terms of burst loss probability and channel utilization. 相似文献
997.
998.
福田作为中国全系列商用汽车领军企业,为了能够确立竞争优势,积极打造服务体系。在无线技术被广泛利用的今天,福田为了避免库存,时效,准确率等问题,经过慎重选型,选择了美国讯宝科技公司及其合作伙伴。条形码结合无线技术不但降低了库存成本,提高了客户响应速度,而且提供了准确及时的库存信息,大大提高了福田汽车在商用车市场的竞争力。 相似文献
999.
a—Si太阳电池陷光结构的新模型及其优化 总被引:3,自引:3,他引:3
我们在分析陷光结构的表面形貌后,对陷光结构提出一个新的模型,并用它计算和分析析射率、形貌和膜厚等参数对陷光效果的影响。通过计算,我们找出这些参数的最佳值,并依此对陷光结构进行优化,以提高非晶硅太阳电池的效率和稳定性。 相似文献
1000.
Lode Nachtergaele Toon Gijbels Jan Bormans Francky Catthoor Ivo Bolsens 《The Journal of VLSI Signal Processing》2001,27(1-2):161-169
Upcoming multi-media compression applications will require high memory bandwidth. In this paper, we estimate that a software reference implementation of an MPEG-4 video decoder typically requires 200 Mtransfers/s to memory to decode 1 CIF (352×288) Video Object Plane (VOP) at 30 frames/s. This imposes a high penalty in terms of power but also performance.However, we also show that we can heavily improve on the memory transfers, without sacrificing speed (even gaining about 10% on cache misses and cycles for a DEC Alpha), by aggressive code transformations. For this purpose, we have manually applied an extended version of our data transfer and storage exploration (DTSE) methodology, which was originally developed for custom hardware implementations. 相似文献