全文获取类型
收费全文 | 2617篇 |
免费 | 142篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 32篇 |
综合类 | 8篇 |
化学工业 | 641篇 |
金属工艺 | 46篇 |
机械仪表 | 28篇 |
建筑科学 | 174篇 |
矿业工程 | 6篇 |
能源动力 | 74篇 |
轻工业 | 219篇 |
水利工程 | 20篇 |
石油天然气 | 5篇 |
无线电 | 257篇 |
一般工业技术 | 531篇 |
冶金工业 | 271篇 |
原子能技术 | 17篇 |
自动化技术 | 433篇 |
出版年
2023年 | 40篇 |
2022年 | 42篇 |
2021年 | 109篇 |
2020年 | 55篇 |
2019年 | 63篇 |
2018年 | 60篇 |
2017年 | 64篇 |
2016年 | 92篇 |
2015年 | 69篇 |
2014年 | 122篇 |
2013年 | 142篇 |
2012年 | 156篇 |
2011年 | 197篇 |
2010年 | 118篇 |
2009年 | 119篇 |
2008年 | 135篇 |
2007年 | 125篇 |
2006年 | 118篇 |
2005年 | 109篇 |
2004年 | 84篇 |
2003年 | 62篇 |
2002年 | 58篇 |
2001年 | 31篇 |
2000年 | 47篇 |
1999年 | 48篇 |
1998年 | 75篇 |
1997年 | 48篇 |
1996年 | 53篇 |
1995年 | 37篇 |
1994年 | 35篇 |
1993年 | 23篇 |
1992年 | 13篇 |
1991年 | 21篇 |
1990年 | 12篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 12篇 |
1977年 | 5篇 |
1976年 | 11篇 |
1973年 | 5篇 |
1916年 | 4篇 |
排序方式: 共有2762条查询结果,搜索用时 875 毫秒
71.
Driven by promising recent results, there has been a revived interest in the thermoelectric properties of organic (semi)conductors. Concomitantly, there is a need to probe the Seebeck coefficient S of modestly conducting materials in thin film geometry. Here we show that geometries that seem desirable from a signal-to-noise perspective may induce systematic errors in the measured value of S, Sm, by a factor 3 or more. The enhancement of Sm by the device geometry is related to competing conduction paths outside the region between the electrodes. We derive a universal scaling curve that allows correcting for this and show that structuring the semiconductor is not needed for the optimal electrode configuration, being a set of narrow, parallel strips. 相似文献
72.
Statistical testing for sufficient control chart performances during monitoring of grouped processes
Kevin Nikolai Kostyszyn Tobias Claus Brandstätter Thomas Vollmer Robert Schmitt 《Quality and Reliability Engineering International》2021,37(6):2555-2567
With ISO 7870-8, a standardized application of charting techniques for short runs and small mixed batches was presented in 2017. Similar to various scientific approaches, it requires that sample values from grouped processes follow nearly identical distributions. In practice, however, there tend to be differences between distribution parameters. Moreover, equal parameters do not ensure that distributions are properly aligned to the center line and control limits of the chart. These facts can lead to undesired control chart performances which can be expressed by average run lengths (ARL) during in-control and out-of-control conditions. In this work, a statistical test for sufficient control chart performances during monitoring of grouped processes based on preliminary samples is proposed. Control chart performances are defined as sufficient when they deviate within acceptable ranges from usual performances during single process monitoring in mass production. The ARL resulting from estimated distributions and planned production sequences is used as test statistic and calculated via the Markov chain approach. Exemplary tests are executed for scenarios with individuals and cumulated sum (CUSUM) charts. A simulative determination of error rates resulting from the ARL-based testing demonstrates its effectiveness in testing for sufficient control chart performances compared to an indirect testing with Levene's test and a one-way analysis of variance (ANOVA). 相似文献
73.
74.
A cost‐effective and robust encapsulation system for chemical admixtures with delayed release mechanisms for construction materials like dry mix mortars is presented. Based on supplementary cementitious materials, a superplasticizer was encapsulated in matrix‐based encapsulations. Subsequently, the particle characteristics of the agglomerates and the release behavior of the superplasticizer were examined. The main objective of this research was to prove the functionality of such encapsulations for the future use in construction materials. The results obtained indicate that the performance of construction chemicals could be improved by encapsulation and controlled release for the future development of new construction materials. Furthermore, material characteristics of the supplementary cementitious material like the incline to excessive dusting or the materials density were improved by encapsulation. 相似文献
75.
Nathaniel A. Riordan Chaturvedi Gogineni Shane R. Johnson Xianfeng Lu Tom Tiedje Ding Ding Yong-Hang Zhang Rafael Fritz Kolja Kolata Sangam Chatterjee Kerstin Volz Stephan W. Koch 《Journal of Materials Science: Materials in Electronics》2012,23(10):1799-1804
Bulk and quantum well GaAs1?xBix/GaAs layers with Bi mole fractions from 0.02 to 0.10 are grown by molecular-beam epitaxy at temperatures ranging from 280 to 320?°C. The samples are characterized using temperature and pump-power dependent photoluminescence measurements covering 8–300?K and 1–250?mW (7–1,800?W/cm2), respectively. The results indicate that there is strong reduction in bandgap energy with the incorporation of small amounts of Bi and that GaAsBi most likely forms a weak type-I band alignment with GaAs. 相似文献
76.
Alexander Gredner Christoph Gerhard Stephan Wieneke Kai Schmidt Wolfgang Viol 《材料科学与工程:中英文B版...》2013,(6):346-351
In this work, a novel atmospheric pressure plasma-assisted excimer laser annealing method for increasing the generation efficiency of poly-crystalline silicon from amorphous silicon layers is presented. Here, both the plasma and the laser propagate coaxially in order to generate energetic synergies. The influence of different process gases and plasma discharge modes as well as the working distance were investigated. Depending on the particularly applied plasma, the crystalline area was increased by a factor of approx. 1.1 to 1.9, where the highest efficiency was observed when introducing an argon plasma beam to the annealing process. 相似文献
77.
Christoph Spiegel Manfred Kraut Georg Rabsch Christof Küsters Wolfgang Augustin Stephan Scholl 《化学工程与技术》2019,42(10):2067-2075
The application of highly effective microstructured devices in continuous production and industrial environments is frequently prone to fouling. A new method is presented to characterize fouling in these microstructures. Thermal fouling of aqueous solutions containing whey protein were used as a test system. Different fouling effects could be observed and distinguished. Integral fouling indicators, such as thermal fouling resistance and pressure drop, as conventional criteria for the occurrence of fouling were compared with direct local optical observation. Low thermal fouling resistances could be detected. 相似文献
78.
79.
Dmitry V. Volodkin Stephan Schmidt Paulo Fernandes Natalia I. Larionova Gleb B. Sukhorukov Claus Duschl Helmuth Möhwald Regine von Klitzing 《Advanced functional materials》2012,22(9):1914-1922
Formulation of therapeutic proteins into particulate forms is a main strategy for site‐specific and prolonged protein delivery as well as for protection against degradation. Precise control over protein particle size, dispersity, purity, as well as mild preparation conditions and minimal processing steps are highly desirable. It is, however, hard to fit all these criteria with conventional preparation techniques. Here a one‐step hard‐templating synthesis of microparticles composed of functional, non‐denatured protein is reported. The method is based on filling porous CaCO3 microtemplates with the protein near to its isoelectric point (pI) followed by pH‐ or EDTA‐mediated dissolution of the tempplates. In principle, a wide variety of proteins can be converted into microparticles using this approach. The main requirement is an overlap of the protein insolubility and a template solubility for a certain parameter (here pH or EDTA). Here the formulation of insulin particles is studied in detail and it is shown that particles consisting of high molecular weight protein (catalase) can also be prepared. In this context, the synthesis of CaCO3 templates with controlled size, the mechanism of the protein microparticle formation and mechanical properties of the microparticles are discussed. For the first time, the fabrication of mesoporous monodispersed CaCO3 microtemplates with identical porocity but tuned diameter from 3 to 20 μm is demonstrated. The protein particle diameter can be adjusted by choosing the appropriate template size that is critical for successful pulmonary delivery of insulin. As a first step towards insulin delivery, the in vitro release of insulin at physiological conditions is studied. 相似文献
80.