全文获取类型
收费全文 | 792篇 |
免费 | 39篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 18篇 |
化学工业 | 191篇 |
金属工艺 | 8篇 |
机械仪表 | 18篇 |
建筑科学 | 26篇 |
矿业工程 | 5篇 |
能源动力 | 30篇 |
轻工业 | 99篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 67篇 |
一般工业技术 | 157篇 |
冶金工业 | 48篇 |
原子能技术 | 3篇 |
自动化技术 | 157篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 19篇 |
2021年 | 34篇 |
2020年 | 20篇 |
2019年 | 30篇 |
2018年 | 21篇 |
2017年 | 23篇 |
2016年 | 24篇 |
2015年 | 25篇 |
2014年 | 37篇 |
2013年 | 42篇 |
2012年 | 41篇 |
2011年 | 55篇 |
2010年 | 44篇 |
2009年 | 34篇 |
2008年 | 45篇 |
2007年 | 37篇 |
2006年 | 26篇 |
2005年 | 19篇 |
2004年 | 17篇 |
2003年 | 14篇 |
2002年 | 18篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1974年 | 5篇 |
1972年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有833条查询结果,搜索用时 15 毫秒
81.
Marcus Schoßig Armin ZankelChristian Bierögel Peter PöltWolfgang Grellmann 《Composites Science and Technology》2011,71(3):257-265
The damage mechanisms of short glass fibre reinforced polypropylene (PP) and polybutene-1 (PB-1) materials were investigated. For this purpose, in situ tensile tests were conducted in the environmental scanning electron microscope (ESEM) while simultaneously recording the acoustic emission (AE). To be able to observe damage mechanisms directly during loading, notched specimens were used. This method allows the direct correlation of the recorded load - elongation data with observed damage mechanisms, as well as correlations with acoustic emission data. Hence, it is possible to describe the damage kinetics of short glass fibre composite.It was found that different bonding conditions of the two investigated materials result in different damage mechanisms as well as in different AE behaviour. For fibre reinforced PP with excellent bonding conditions of the fibres in the polymeric matrix, fibre fracture, slipping of fibres in the delamination area, debonding and pull-out with matrix yielding was observed. The determined AE parameter amplitude Ap and energy EAE for the PB-1 material are lower because of the weak bonding of the fibres to the PB-1-matrix. Hence, energy dissipative damage mechanisms like pull-out with matrix yielding can occur only in a limited part of such materials. 相似文献
82.
Synthesis of novel tricalcium phosphate-bioactive glass composite and functionalization with rhBMP-2
Schickle K Zurlinden K Bergmann C Lindner M Kirsten A Laub M Telle R Jennissen H Fischer H 《Journal of materials science. Materials in medicine》2011,22(4):763-771
A functionalization is required for calcium phosphate-based bone substitute materials to achieve an entire bone remodeling.
In this study it was hypothesized that a tailored composite of tricalcium phosphate and a bioactive glass can be loaded sufficiently
with rhBMP-2 for functionalization. A composite of 40 wt% tricalcium phosphate and 60 wt% bioactive glass resulted in two
crystalline phases, wollastonite and rhenanite after sintering. SEM analysis of the composite’s surface revealed a spongious
bone-like morphology after treatment with different acids. RhBMP-2 was immobilized non-covalently by treating with chrome
sulfuric acid (CSA) and 3-aminopropyltriethoxysilane (APS) and covalently by treating with CSA/APS, and additionally with
1,1′-carbonyldiimidazole. It was proved that samples containing non-covalently immobilized rhBMP-2 on the surface exhibit
significant biological activity in contrast to the samples with covalently bound protein on the surface. We conclude that
a tailored composite of tricalcium phosphate and bioactive glass can be loaded sufficiently with BMP-2. 相似文献
83.
Armin Eftekhari Massoud Babaie-ZadehHamid Abrishami Moghaddam 《Signal processing》2011,91(7):1589-1603
As an alternative to adaptive nonlinear schemes for dimensionality reduction, linear random projection has recently proved to be a reliable means for high-dimensional data processing. Widespread application of conventional random projection in the context of image analysis is, however, mainly impeded by excessive computational and memory requirements. In this paper, a two-dimensional random projection scheme is considered as a remedy to this problem, and the associated key notion of concentration of measure is closely studied. It is then applied in the contexts of image classification and sparse image reconstruction. Finally, theoretical results are validated within a comprehensive set of experiments with synthetic and real images. 相似文献
84.
Maljusch A Schönberger B Lindner A Stratmann M Rohwerder M Schuhmann W 《Analytical chemistry》2011,83(15):6114-6120
The integration of a scanning Kelvin probe (SKP) and a scanning electrochemical microscope (SECM) into a single SKP-SECM setup, the concept of the proposed system, its technical realization, and first applications are presented and discussed in detail. A preloaded piezo actuator placed in a grounded stainless steel case was used as the driving mechanism for oscillation of a Pt disk electrode as conventionally used in SECM when the system was operated in the SKP mode. Thus, the same tip is recording the contact potential difference (CPD) during SKP scanning and is used as a working electrode for SECM imaging in the redox-competition mode (RC-SECM). The detection of the local CPD is established by amplification of the displacement current at an ultralow noise operational amplifier and its compensation by application of a variable backing potential (V(b)) in the external circuit. The control of the tip-to-sample distance is performed by applying an additional alternating voltage with a much lower frequency than the oscillation frequency of the Kelvin probe. The main advantage of the SKP-SECM system is that it allows constant distance measurements of the CPD in air under ambient conditions and in the redox-competition mode of the SECM in the electrolyte of choice over the same sample area without replacement of the sample or exchange of the working electrode. The performance of the system was evaluated using a test sample made by sputtering thin Pt and W films on an oxidized silicon wafer. The obtained values of the CPD correlate well with known data, and the electrochemical activity for oxygen reduction is as expected higher over Pt than W. 相似文献
85.
Armin Biere Edmund M. Clarke Yunshan Zhu 《Electronic Notes in Theoretical Computer Science》2001,23(2):34-45
The verification process of reactive systems in local model checking [1,7] and in explicit state model checking is[13,15] on-the-fly. Therefore only those states of a system have to be traversed that are necessary to prove a property. In addition, if the property does not hold, than often only a small subset of the state space has to be traversed to produce a counterexample. Global model checking [6,23] and, in particular, symbolic model checking [4,22] can utilize compact representations of the state space, e.g. BDDs [3], to handle much larger designs than what is possible with local and explicit model checking. We present a new model checking algorithm for LTL that combines both approaches. In essence, it is a generalization of the tableau construction of [1] that enables the use of BDDs but still is on-the-fly. 相似文献
86.
Mischa Schmidt Jan Seedorf Stefano Napolitano Rosario G. Garroppo Andrea Cavaliere Thilo Ewald Armin Jahanpanah Zbigniew Kopertowski Marcin Pilarski Pawel Grochocki 《Peer-to-Peer Networking and Applications》2013,6(2):134-154
Application Layer Traffic Optimization (ALTO) has recently gained attention in the research and standardisation community as a way for a network operator to guide the peer selection process of distributed applications by providing network layer topology information. In particular P2P applications are expected to gain from ALTO, due to the many connections peers form among each other, often without taking network layer topology information into account. In this paper, we present results of an extensive intra-ISP trial with an ALTO-enhanced P2P filesharing software. In summary, our results show that—depending on the concrete setting and on the distribution of upload capacity in the network—ALTO enables an ISP to save operational costs significantly while not degrading application layer performance noticeably. In addition, based on our experience we are able to give advice to operators on how to save costs with ALTO while not sacrificing application layer performance at all. 相似文献
87.
88.
89.
90.
Ermittlung der mechanischen Eigenschaften unterschiedlicher Bereiche gegossener Walzen mit 360 mm Ballendurchmesser und 200 mm Zapfendurchmesser aus drei Schmelzen eines Gußeisens mit rd. 3% C, 0,8% Si, 0,8% Mn, 0,14% P, 0,014% S, 14,2% Cr, 0,35% Mo und 0,5% Ni in zwei Wärmebehandlungszuständen. Zahlenmäßiger Zusammenhang zwischen der Biegefließgrenze und geeigneten Kennwerten für den Gefügezustand unter Bezugnahme auf die Beanspruchungsrichtung. Einfluß des Gefügezustandes auf das Formänderungsverhalten im statischen Biegeversuch. 相似文献