全文获取类型
收费全文 | 3272篇 |
免费 | 83篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 32篇 |
综合类 | 10篇 |
化学工业 | 695篇 |
金属工艺 | 83篇 |
机械仪表 | 59篇 |
建筑科学 | 75篇 |
矿业工程 | 1篇 |
能源动力 | 100篇 |
轻工业 | 237篇 |
水利工程 | 12篇 |
石油天然气 | 4篇 |
无线电 | 467篇 |
一般工业技术 | 558篇 |
冶金工业 | 577篇 |
原子能技术 | 16篇 |
自动化技术 | 433篇 |
出版年
2023年 | 17篇 |
2022年 | 67篇 |
2021年 | 70篇 |
2020年 | 27篇 |
2019年 | 32篇 |
2018年 | 50篇 |
2017年 | 45篇 |
2016年 | 58篇 |
2015年 | 67篇 |
2014年 | 97篇 |
2013年 | 229篇 |
2012年 | 155篇 |
2011年 | 221篇 |
2010年 | 183篇 |
2009年 | 205篇 |
2008年 | 189篇 |
2007年 | 196篇 |
2006年 | 135篇 |
2005年 | 127篇 |
2004年 | 110篇 |
2003年 | 83篇 |
2002年 | 98篇 |
2001年 | 67篇 |
2000年 | 58篇 |
1999年 | 54篇 |
1998年 | 139篇 |
1997年 | 84篇 |
1996年 | 77篇 |
1995年 | 42篇 |
1994年 | 46篇 |
1993年 | 35篇 |
1992年 | 32篇 |
1991年 | 34篇 |
1990年 | 26篇 |
1989年 | 25篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 16篇 |
1985年 | 14篇 |
1984年 | 18篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1973年 | 5篇 |
1971年 | 4篇 |
排序方式: 共有3359条查询结果,搜索用时 15 毫秒
21.
This investigation prepares a low-resistivity and self-passivated Cu(In) thin film. The dissociation behaviors of dilute Cu-alloy
thin films, containing 1.5–5at.%In, were prepared on glass substrates by a cosputter deposition, and were subsequently annealed
in the temperature range of 200–600 °C for 10–30 min. Thus, self-passivated Cu thin films in the form In2O3/Cu/SiO2 were obtained by annealing Cu(In) alloy films at an elevated temperature. Structural analysis indicated that only strong
copper diffraction peaks were detected from the as-deposited film, and an In2O3 phase was formed on the surface of the film by annealing the film at an elevated temperature under oxygen ambient. The formation
of In2O3/Cu/SiO2 improved the resistivity, adhesion to SiO2, and passivative capability of the studied film. A dramatic reduction in the resistivity of the film occurred at 500 °C,
and was considered to be associated with preferential indium segregation during annealing, yielding a low resistivity below
2.92 μΩcm. The results of this study can be potentially exploited in the application of thin-film transistor–liquid crystal display
gate electrodes and copper metallization in integrated circuits. 相似文献
22.
Hung-Tse Chen Hsieh S.-I. Chrong-Jung Lin Ya-Chin King 《Electron Device Letters, IEEE》2007,28(6):499-501
A new NAND-type nonvolatile memory with a field-enhancing tip structure embedded in low-temperature polycrystalline silicon (LTPS) panel was demonstrated on a glass substrate for the first time. A thin-film transistor (TFT) metal-oxide-nitride-oxide-silicon (MONOS) device based on sequential lateral solidification crystallization with a fully depleted poly-Si channel, an oxide-nitride-oxide stack gate dielectric, and a metal gate is integrated into a NAND array. A NAND test array based on p-channel LTPS TFTs exhibits good cycling endurance and data retention properties and negligible program and read disturbance. These results strongly support the claim that this TFT-MONOS device is a promising candidate for use in embedded nonvolatile memory for system-on-panel and 3-D IC applications 相似文献
23.
The transport layer in the network protocol stack serves as a liaison between the application and the underlying network. Any quality of service provided by the network thus has to be effectively translated by the transport layer protocol in order to be enjoyed by the applications. In this article, we argue for a fundamental rethinking of the transport layer design to facilitate such QoS delivery. We identify the key requirement for a QoS enabling transport layer protocol as the ability to effectively handle multiplicity in terms of user differentiation levels, network resources, and service models. However, TCP, the transport layer protocol predominantly used in the Internet, is unable to support such multiplicity due to its single-state design. We extend TCP to a parallel transport layer protocol called parallel TCP (pTCP) that can tackle the different dimensions of multiplicity, and hence enable varying classes of QoS to applications. We discuss the applicability of pTCP in three specific domains with different levels of network support for QoS, and present simulation results substantiating our arguments. 相似文献
24.
Aircraft type recognition in satellite images 总被引:4,自引:0,他引:4
Hsieh J.-W. Chen J.-M. Chuang C.-H. Fan K.-C. 《Vision, Image and Signal Processing, IEE Proceedings -》2005,152(3):307-315
This paper proposes a hierarchical classification algorithm to accurately recognise aircraft in satellite images. Before recognition, a novel symmetry-based algorithm is proposed to estimate an aircraft's optimal orientation for rotation correction. Then, distinguishable features are derived from each aircraft for aircraft recognition. However, different features have different discrimination abilities to recognise the types of aircraft. Therefore, a novel booting algorithm is proposed to learn a set of proper weights from training samples for feature integration. Owing to this integration, significant improvements in terms of recognition accuracy and robustness can be achieved. Last, a hierarchical recognition scheme is proposed to recognise the types of aircraft by using the area feature, first for a rough categorisation on which detailed classifications are then achieved using several suggested features. Experiments were conducted on a wide variety of satellite images. Experimental results reveal the feasibility and validity of the proposed approach in recognising aircraft in satellite images. 相似文献
25.
Using AuGeNiCr multilayered metals as the wafer bonding medium, long-wavelength GaInAsP/InP vertical cavity surface emitting lasers employing Al-oxide/Si as the upper and lower distributed Bragg reflectors were fabricated on Si substrate with the bonding interface formed outside the vertical cavity surface emitting laser cavity. Laser emission at 1.545 μm was measured under pulsed operations near room temperature. The low-temperature metallic bonding process demonstrates a great potential in device fabrication 相似文献
26.
Hen-So Chang J. X. Pon Ker-Chang Hsieh C. C. Chen 《Journal of Electronic Materials》2001,30(9):1171-1177
Two types of samples were applied in this wire-bond evaluation work for an Al-pad diffusion process. One was finished product
for the cross-section examination of wire-bond and the other was without compound encapsulant used for the plane view examination
of wire-bond interface. These samples were aged at 175 C in air from 0 h to 1008 h. It is found that the normal product which
was ready on board existed ∼1 μm Au2Al and Au5Al2 phases. The Au2Al phase was then transformed to Au5Al2 phase in a 4 ∼ 72 h aging period. The Au4Al phase formed along with the Au5Al2 phase in 72 h to 240 h aging period showing some porosity within the reacted phases. The total phase thickness increased
to ∼4μm after 240 h aging. The Au4Al phase became the major phase after 336 aging h. The reacted phase layer thickness increased to ∼6 μm and reached the steady
state. A titanium-rich thin layer was also induced within the reacted phase layer. Three ternary phases as AlAu2Ti, AlAuTi, and Al2Au2Ti are found in this titanium-rich layer. In particular, Al2Au2Ti could be a new phase. 相似文献
27.
The standard hospital room interface for control of communication and entertainment devices assumes a patient has the ability to hold and press mechanical switches. If the patient does not have these abilities, then the patient must wait for a nurse to walk by the room to ask for help. Mobile devices using the Android and iOS operating systems are compared to accommodate the limitations of a patient for communication and control of the hospital room environment. In order to design an appropriate system, analysis of currently available off-the-shelf technology is performed to find the appropriate configuration that is compatible with the hospital room environment and covers a clear patient need. Evaluation of components for a fully integrated system is shown. Strengths and weaknesses of each technology are discussed. Progress toward an integrated solution on a tablet is provided in the conclusion. 相似文献
28.
29.
The realisation of a microwave filter is presented by using the asymmetrical compact microstrip resonator and floating plate coupling structures. The filter demonstrates the properties of low insertion loss, wide pass bandwidth and two controllable transmission zeros, which results in fast roll-off responses near to the corner frequencies of the passband. It also has the advantages of compact size, ease of fabrication and absence of via holes. An X-band prototype with 34% fractional bandwidth was designed and fabricated to verify the proposed design concept. Good agreement between simulation and measurement was obtained. 相似文献
30.
Jenn-Ming Song Meng-Ju Lin Kun-Hung Hsieh Tsung-Yun Pai Yi-Shao Lai Ying-Ta Chiu 《Journal of Electronic Materials》2013,42(9):2813-2821
In this study, the high-speed deformation behavior of solder joints formed with Pb-free Zn-Sn and commercial Pb-Sn alloys bonded on different substrates was investigated by the ball impact test method. Overall, Zn-Sn joints exhibited greater impact strength but inferior impact toughness than Pb-Sn joints. This can be ascribed to the high hardness of Zn-Sn solders resulting in partial or overall interfacial fracture. In contrast, the joints with soft Pb-Sn solders all showed a ductile fracture feature. It is suggested that, for the joints revealing brittle fracture, the impact toughness (impact energy) increased with the plastic ability of interfacial intermetallic compounds, while for those showing a ductile fracture mode, the impact energy deteriorated with a hardened solder matrix resulting from substrate dissolution. 相似文献