全文获取类型
收费全文 | 160767篇 |
免费 | 8013篇 |
国内免费 | 3957篇 |
专业分类
电工技术 | 5552篇 |
技术理论 | 9篇 |
综合类 | 7444篇 |
化学工业 | 24278篇 |
金属工艺 | 9005篇 |
机械仪表 | 8051篇 |
建筑科学 | 8594篇 |
矿业工程 | 2926篇 |
能源动力 | 3420篇 |
轻工业 | 8942篇 |
水利工程 | 2545篇 |
石油天然气 | 4748篇 |
武器工业 | 695篇 |
无线电 | 18423篇 |
一般工业技术 | 25593篇 |
冶金工业 | 6123篇 |
原子能技术 | 1315篇 |
自动化技术 | 35074篇 |
出版年
2024年 | 325篇 |
2023年 | 1385篇 |
2022年 | 2510篇 |
2021年 | 3527篇 |
2020年 | 2575篇 |
2019年 | 2124篇 |
2018年 | 16440篇 |
2017年 | 15769篇 |
2016年 | 12166篇 |
2015年 | 3745篇 |
2014年 | 4345篇 |
2013年 | 5075篇 |
2012年 | 8355篇 |
2011年 | 14868篇 |
2010年 | 13067篇 |
2009年 | 10145篇 |
2008年 | 11175篇 |
2007年 | 11939篇 |
2006年 | 4240篇 |
2005年 | 4725篇 |
2004年 | 3535篇 |
2003年 | 3316篇 |
2002年 | 2664篇 |
2001年 | 1982篇 |
2000年 | 1989篇 |
1999年 | 1897篇 |
1998年 | 1498篇 |
1997年 | 1305篇 |
1996年 | 1256篇 |
1995年 | 953篇 |
1994年 | 805篇 |
1993年 | 539篇 |
1992年 | 430篇 |
1991年 | 325篇 |
1990年 | 248篇 |
1989年 | 209篇 |
1988年 | 180篇 |
1987年 | 97篇 |
1986年 | 78篇 |
1985年 | 52篇 |
1984年 | 39篇 |
1968年 | 43篇 |
1966年 | 42篇 |
1965年 | 45篇 |
1962年 | 65篇 |
1961年 | 57篇 |
1960年 | 46篇 |
1959年 | 39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 15 毫秒
991.
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
992.
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
993.
994.
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
995.
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
996.
This paper presents a 2D to 3D conversion scheme to generate a 3D human model using a single depth image with several color
images. In building a complete 3D model, no prior knowledge such as a pre-computed scene structure and photometric and geometric
calibrations is required since the depth camera can directly acquire the calibrated geometric and color information in real
time. The proposed method deals with a self-occlusion problem which often occurs in images captured by a monocular camera.
When an image is obtained from a fixed view, it may not have data for a certain part of an object due to occlusion. The proposed
method consists of following steps to resolve this problem. First, the noise in a depth image is reduced by using a series
of image processing techniques. Second, a 3D mesh surface is constructed using the proposed depth image-based modeling method.
Third, the occlusion problem is resolved by removing the unwanted triangles in the occlusion region and filling the corresponding
hole. Finally, textures are extracted and mapped to the 3D surface of the model to provide photo-realistic appearance. Comparison
results with the related work demonstrate the efficiency of our method in terms of visual quality and computation time. It
can be utilized in creating 3D human models in many 3D applications. 相似文献
997.
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
998.
The Web has evolved into a dominant digital medium for conducting many types of online transactions such as shopping, paying
bills, making travel plans, etc. Such transactions typically involve a number of steps spanning several Web pages. For sighted
users these steps are relatively straightforward to do with graphical Web browsers. But they pose tremendous challenges for
visually impaired individuals. This is because screen readers, the dominant assistive technology used by visually impaired
users, function by speaking out the screen’s content serially. Consequently, using them for conducting transactions can cause
considerable information overload. But usually one needs to browse only a small fragment of a Web page to do a step of a transaction
(e.g., choosing an item from a search results list). Based on this observation this paper presents a model-directed transaction
framework to identify, extract and aurally render only the “relevant” page fragments in each step of a transaction. The framework
uses a process model to encode the state of the transaction and a concept model to identify the page fragments relevant for
the transaction in that state. We also present algorithms to mine such models from click stream data generated by transactions
and experimental evidence of the practical effectiveness of our models in improving user experience when conducting online
transactions with non-visual modalities. 相似文献
999.
1000.
SimRank has become an important similarity measure to rank web documents based on a graph model on hyperlinks. The existing
approaches for conducting SimRank computation adopt an iteration paradigm. The most efficient deterministic technique yields
O(n3)O\left(n^3\right) worst-case time per iteration with the space requirement O(n2)O\left(n^2\right), where n is the number of nodes (web documents). In this paper, we propose novel optimization techniques such that each iteration
takes O (min{ n ·m , nr })O \left(\min \left\{ n \cdot m , n^r \right\}\right) time and O ( n + m )O \left( n + m \right) space, where m is the number of edges in a web-graph model and r ≤ log2 7. In addition, we extend the similarity transition matrix to prevent random surfers getting stuck, and devise a pruning
technique to eliminate impractical similarities for each iteration. Moreover, we also develop a reordering technique combined
with an over-relaxation method, not only speeding up the convergence rate of the existing techniques, but achieving I/O efficiency
as well. We conduct extensive experiments on both synthetic and real data sets to demonstrate the efficiency and effectiveness
of our iteration techniques. 相似文献