全文获取类型
收费全文 | 255972篇 |
免费 | 16030篇 |
国内免费 | 8114篇 |
学科分类
工业技术 | 280116篇 |
出版年
2024年 | 770篇 |
2023年 | 2960篇 |
2022年 | 5489篇 |
2021年 | 7428篇 |
2020年 | 5633篇 |
2019年 | 4531篇 |
2018年 | 18918篇 |
2017年 | 18560篇 |
2016年 | 14664篇 |
2015年 | 7595篇 |
2014年 | 8900篇 |
2013年 | 10906篇 |
2012年 | 14577篇 |
2011年 | 21572篇 |
2010年 | 18759篇 |
2009年 | 15699篇 |
2008年 | 16746篇 |
2007年 | 16995篇 |
2006年 | 9623篇 |
2005年 | 9450篇 |
2004年 | 6695篇 |
2003年 | 5712篇 |
2002年 | 4650篇 |
2001年 | 3864篇 |
2000年 | 4012篇 |
1999年 | 4311篇 |
1998年 | 3619篇 |
1997年 | 3098篇 |
1996年 | 2880篇 |
1995年 | 2316篇 |
1994年 | 1871篇 |
1993年 | 1462篇 |
1992年 | 1175篇 |
1991年 | 874篇 |
1990年 | 696篇 |
1989年 | 576篇 |
1988年 | 472篇 |
1987年 | 336篇 |
1986年 | 238篇 |
1985年 | 204篇 |
1984年 | 122篇 |
1983年 | 93篇 |
1982年 | 101篇 |
1981年 | 67篇 |
1980年 | 56篇 |
1976年 | 49篇 |
1968年 | 49篇 |
1965年 | 51篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
In this paper, we present an efficient way of implementing OpenGL ES 1.1 3D graphics API library for the environments with
hardware-supported OpenGL facility, typically as desktop PCs. Although OpenGL ES was started from the existing OpenGL features,
it rapidly became the standard 3D graphics library customized for embedded systems through introducing fixed-point arithmetic
operations, buffer management with fixed-point data type supports, completely new texture mapping functions and others. Currently,
it is the official 3D graphics API for Google Android, Apple iPhone, Sony PlayStation3, etc. In this paper, we achieved improvements
on the arithmetic operations for the fixed-point number representation, which is the most characteristic data type for OpenGL
ES 1.1. For the conversion of fixed-point data types to the floating-point number representations for the underlying OpenGL,
we show the way of efficient conversion processes even with satisfying OpenGL ES standard requirements. We also introduced
a specialized memory management scheme to manage the converted data from the buffer containing fixed-point numbers. In the
case of texture processing, the requirements in both standards are quite different, and thus we used completely new software-implementations.
Our final implementation of OpenGL ES library provides all of more than 200 functions in the standard specification and passed
its conformance test, to show its compliance with the standard. From the efficiency point of view, we measured its execution
times for several OpenGL ES-specific application programs and achieved remarkable improvements. 相似文献
942.
Bettina Berendt 《Data mining and knowledge discovery》2012,24(3):697-737
Over the last decade, privacy has been widely recognised as one of the major problems of data collections in general and the
Web in particular. This concerns specifically data arising from Web usage (such as querying or transacting) and social networking
(characterised by rich self-profiling including relational information) and the inferences drawn from them. The data mining
community has been very conscious of these issues and has addressed in particular the inference problems through various methods
for “privacy-preserving data mining” and “privacy-preserving data publishing”. However, it appears that these approaches by
themselves cannot effectively solve the privacy problems posed by mining. We argue that this is due to the underlying notions
of privacy and of data mining, both of which are too narrow. Drawing on notions of privacy not only as hiding, but as control
and negotiation, as well as on data mining not only as modelling, but as the whole cycle of knowledge discovery, we offer
an alternative view. This is intended to be a comprehensive view of the privacy challenges as well as solution approaches
along all phases of the knowledge discovery cycle. The paper thus combines a survey with an outline of an agenda for a comprehensive,
interdisciplinary view of Web mining and privacy. 相似文献
943.
Efficient compression and network adaptive video coding for distributed video surveillance 总被引:1,自引:1,他引:0
The availability of cheap network based video cameras and the prevalence of wireless networks has lead to a major thrust towards
deployment of large scale Distributed Video Surveillance (DVS) systems. This has opened up an important area of research to
deal with the issues involved in DVS system for efficient collection and transmission of large scale video streams from the
cameras at the guarded sites, to the end users in possibly constrained network conditions. In this paper, we propose a framework
based on content-based video classification and scalable compression scheme to provide a robust bandwidth efficient video
transmission for DVS. The scheme builds on a Discrete Wavelet Transform (DWT) based Color-Set Partitioning for Hierarchical
Trees (CSPIHT) coding to obtain a scalable bitstream. Wavelet domain segmentation and compression assists in development of
a DVS architecture. The architecture includes a novel module for dynamic allocation of Network bandwidth based on the current
available resources and constraints. Different frame constituents are optimally coded based on their relative significance,
perceptual quality, and available estimate of network bandwidth. Experimental result over different video sequences and simulations
for Network conditions demonstrate the efficient performance of the approach. 相似文献
944.
945.
Jung Nam Bae Jin Young Kim Geon Kim Yong Tae Lee Jae Sang Cha 《Multimedia Tools and Applications》2012,57(2):359-372
Recently, watermarking based data transmission techniques using terrestrial digital TV signal have been proposed since they
are also cost-free and can overcome the limitations of GPS. However, in the previous watermarking based methods, the detection
accuracy is low and additional data rate is too low. Thus, we propose the throughput enhancement method by employing the TZCD-MBOK
watermarking technique in T-DMB system. By applying the proposed scheme to T-DMB, it allows additional data transmission for
disaster broadcasting and improves efficiency of data transmission in shadow region and indoor to mobile environment through
watermarking spread code. From the simulation results, we confirm the proposed watermarking scheme affected on the existing
T-DMB signal. Moreover, it was also confirmed that the system capacity increases as the power of additional watermarking signal
rose. The results of the paper can be applied to wireless multimedia digital broadcasting systems. 相似文献
946.
Many video service sites headed by YouTube know what content requires copyright protection. However, they lack a copyright
protection system that automatically distinguishes whether uploaded videos contain legal or illegal content. Existing protection
techniques use content-based retrieval methods that compare the features of video. However, if the video encoding has changed
in resolution, bit-rate or codec, these techniques do not perform well. Thus, this paper proposes a novel video matching algorithm
even if the type of encoding has changed. We also suggest an intelligent copyright protection system using the proposed algorithm.
This can serve to automatically prevent the uploading of illegal content. The proposed method has represented the accuracy
of 97% with searching algorithm in video-matching experiments and 98.62% with automation algorithm in copyright-protection
experiments. Therefore, this system could form a core technology that identifies illegal content and automatically excludes
access to illegal content by many video service sites. 相似文献
947.
948.
In this paper we have proposed a dynamic pricing scheme for the contributing peers in the Video on Demand (VoD) system. The
scheme provides an effective mechanism to maximize the profit through the residual resources of the contributing peers. A
utilization function is executed for each contributing peer to estimate the utility factor based on the parameters such as
initial setup cost, holding cost, chaining cost and salvage cost. In this paper, we urge an effective dynamic pricing algorithm
that efficiently utilizes a range of parameters with a varying degree of complexity. The key findings of the algorithm are
(i) each contributing peers are benefitted by the monetary based on its resource contributions to the VoD system and (ii)
a high degree of social optimum is established by proficiently aggregating the contributing peer’s resources with the overall
resources of the VoD system. We validate our claim by simulating the proposed dynamic pricing scheme with other standard pricing
schemes such as altruism, cost model and game theory perspective. The result of our dynamic pricing scheme shows the best
utility factor than other standard pricing schemes. 相似文献
949.
Most algorithms of smoothing schedule compute the required bit rate of video transmission to satisfy all the transmitted data.
In this paper, our proposed tolerable data dropping algorithm can adjust transmitting data to fit available bit rate. MPEG-4
with fine grained scalability (FGS) can support partial data dropping to adapt to available bandwidth network. The algorithm
is based on the minimum variance bandwidth allocation (MVBA) algorithm proposed by Salehi et al. to compute the bit rate such
that still ensuring that the buffer never underflows and overflows for MPEG-4 FGS streams under the limited bandwidth resource.
We prove that our proposed algorithm, named MVBADP, is smoother than the MVBA algorithm. The experimental results show the
peak rate, the number of rate changes, and the ratio of total dropping data, and the PSNR for four test sequences with different
content characteristics. They are varied by buffer sizes and tolerable dropping ratios. We found that the MVBADP algorithm
can reduce the peak rate and the number of changes when the transmitted data are dropped by tolerable dropping ratio, especially
on the video sequences with the high motion and complex texture characteristic and larger size change of the consecutive frame. 相似文献
950.
Andy Gill Tristan Bull Andrew Farmer Garrin Kimmell Ed Komp 《Higher-Order and Symbolic Computation》2012,25(2-4):255-274
In this article we overview the design and implementation of the second generation of Kansas Lava. Driven by the needs and experiences of implementing telemetry decoders and other circuits, we have made a number of improvements to both the external API and the internal representations used. We have retained our dual shallow/deep representation of signals in general, but now have a number of externally visible abstractions for combinatorial and sequential circuits, and enabled signals. We introduce these abstractions, as well as our abstractions for reading and writing memory. Internally, we found the need to represent unknown values inside our circuits, so we made aggressive use of associated type families to lift our values to allow unknowns, in a principled and regular way. We discuss this design decision, how it unfortunately complicates the internals of Kansas Lava, and how we mitigate this complexity. Finally, when connecting Kansas Lava to the real world, the standardized idiom of using named input and output ports is provided by Kansas Lava using a new monad, called Fabric. We present the design of this Fabric monad, and illustrate its use in a small but complete example. 相似文献