全文获取类型
收费全文 | 764篇 |
免费 | 44篇 |
专业分类
电工技术 | 46篇 |
化学工业 | 201篇 |
金属工艺 | 9篇 |
机械仪表 | 8篇 |
建筑科学 | 33篇 |
能源动力 | 36篇 |
轻工业 | 58篇 |
水利工程 | 11篇 |
无线电 | 47篇 |
一般工业技术 | 166篇 |
冶金工业 | 57篇 |
原子能技术 | 2篇 |
自动化技术 | 134篇 |
出版年
2023年 | 15篇 |
2022年 | 25篇 |
2021年 | 32篇 |
2020年 | 18篇 |
2019年 | 36篇 |
2018年 | 26篇 |
2017年 | 17篇 |
2016年 | 26篇 |
2015年 | 43篇 |
2014年 | 32篇 |
2013年 | 52篇 |
2012年 | 42篇 |
2011年 | 60篇 |
2010年 | 17篇 |
2009年 | 24篇 |
2008年 | 22篇 |
2007年 | 29篇 |
2006年 | 27篇 |
2005年 | 24篇 |
2004年 | 18篇 |
2003年 | 19篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 12篇 |
1999年 | 5篇 |
1998年 | 27篇 |
1997年 | 19篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 15篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1987年 | 4篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1936年 | 2篇 |
1933年 | 6篇 |
1932年 | 5篇 |
1931年 | 11篇 |
1930年 | 3篇 |
1920年 | 1篇 |
1919年 | 2篇 |
1910年 | 2篇 |
排序方式: 共有808条查询结果,搜索用时 15 毫秒
201.
202.
E A W. Linke G. Vogelpohl K. Kühner G. Seebauer W. Fritz R. Beryer W. Staedel Max Jakob A E 《Forschung im Ingenieurwesen》1932,3(2):99-108
Ohne Zusammenfassung 相似文献
203.
204.
205.
Detector response to a high-energy physics process is often estimated by Monte Carlo simulation. For purposes of data analysis, the results of this simulation are typically stored in large multi-dimensional histograms, which can quickly become both too large to easily store and manipulate and numerically problematic due to unfilled bins or interpolation artifacts. We describe here an application of the penalized spline technique (Marx and Eilers, 1996) [1] to efficiently compute B-spline representations of such tables and discuss aspects of the resulting B-spline fits that simplify many common tasks in handling tabulated Monte Carlo data in high-energy physics analysis, in particular their use in maximum-likelihood fitting. 相似文献
206.
Pavol Hanus Bernhard Goebel Janis Dingel Johanna Weindl Juergen Zech Zaher Dawy Joachim Hagenauer Jakob C. Mueller 《Electrical Engineering (Archiv fur Elektrotechnik)》2007,90(2):161-173
The DNA sequencing efforts of the past years together with rapid progress in sequencing technology have generated a huge amount
of sequence data available in public molecular databases. This recent development makes it statistically feasible to apply
universal concepts from Shannon’s information theory to problems in molecular biology, e.g to use mutual information for gene
mapping and phylogenetic classification. Additionally, the genetic information in the cell is continuously subject to mutations.
However, it has to be passed from generation to generation with high fidelity, raising the question of existence of error
protection and correction mechanisms similar to those used in technical communication systems. Finally, better understanding
of genetic information processing on the molecular level in the cell can be acquired by looking for parallels to well established
models in communication theory, e.g. there exist analogies between gene expression and frame synchronization. 相似文献
207.
For the design and optimization of methfanation processes detailed modeling and simulation work is advisable. However, only a few kinetics published in literature rely on wide temperature and pressure ranges, which are prevalent at modern methanation applications with dynamic operation. Especially the simulation‐based design of methanation processes with commercial catalysts is difficult due to legal restrictions regarding the publication of kinetic data of those catalysts. In this work, rate equations for the dynamic modeling and simulation of methanation processes operating with commercial Ni/Al2O3 catalysts are selected, adapted, and tested in a dynamic reactor model. The results suggest that the catalyst's nickel content is an indicator for the choice of a rate equation. Testing of the equations in a reactor model meets published data for CO and CO2 methanation and own measurements. 相似文献
208.
Catharina M. Lerche Ida M. Heerfordt Jakob Heydenreich Hans Christian Wulf 《International journal of molecular sciences》2016,17(3)
Daylight-mediated photodynamic therapy (daylight PDT) is a simple and pain free treatment of actinic keratoses. Weather conditions may not always allow daylight PDT outdoors. We compared the spectrum of five different lamp candidates for indoor “daylight PDT” and investigated their ability to photobleach protoporphyrin IX (PpIX). Furthermore, we measured the amount of PpIX activating daylight available in a glass greenhouse, which can be an alternative when it is uncomfortable for patients to be outdoors. The lamps investigated were: halogen lamps (overhead and slide projector), white light-emitting diode (LED) lamp, red LED panel and lamps used for conventional PDT. Four of the five light sources were able to photobleach PpIX completely. For halogen light and the red LED lamp, 5000 lux could photobleach PpIX whereas 12,000 lux were needed for the white LED lamp. Furthermore, the greenhouse was suitable for daylight PDT since the effect of solar light is lowered only by 25%. In conclusion, we found four of the five light sources and the greenhouse usable for indoor daylight PDT. The greenhouse is beneficial when the weather outside is rainy or windy. Only insignificant ultraviolet B radiation (UVB) radiation passes through the greenhouse glass, so sun protection is not needed. 相似文献
209.
ABSTRACTThe aim of the present work was changing the surface properties of alumina ceramic via sintering of samples in spinel MgAl2O4 and magnesia MgO powder bed. During sintering nitrogen and air atmosphere were used; and the reference material was sintered at the same conditions but in an alumina powder bed. All samples were sintered to a density higher than 99.2% of theoretical density of alumina. In order to examine samples SEM, EDX and XRD (X-ray diffraction from 18 to 70 °2Theta) analysis were performed together with B3B flexural strength measurement. Results revealed that by sintering of alumina samples in a spinel powder bed pore-free surfaces were prepared, which had a favourable effect on B3B flexural strength. This was ascribed to the high solubility of Al3+ in spinel at sintering temperatures, which increases the sintering driving force. A further positive effect on B3B flexural strength was observed when samples were sintered in nitrogen instead of air. 相似文献
210.
Matthias Jakob Amira Aissiou William Morrish Frank Marsiglio Muhammad Islam Aras Kartouzian Alkiviathes Meldrum 《Nanoscale research letters》2018,13(1):383
The luminescence dynamics in ensembles of nanocrystals are complicated by a variety of processes, including the size-dependence of the radiative and non-radiative rates in inhomogeneous broadened samples and interparticle interactions. This results in a non-exponential decay, which for the specific case of silicon nanocrystals (SiNCs) has been widely modeled with a Kohlrausch or “stretched exponential” (SE) function. We first derive the population decay function for a luminescence decay following exp[??(t/τ)β]. We then compare the distributions and mean times calculated by assuming that either the luminescence decay or the population decay follows this function and show that the results are significantly different for β much below 1. We then apply these two types of SE functions as well as other models to the luminescence decay data from two thermally grown SiNC samples with different mean sizes. The mean lifetimes are strongly dependent on the experimental setup and the chosen fitting model, none of which appears to adequately describe the ensemble decay dynamics. Frequency-resolved spectroscopy (FRS) techniques are then applied to SiNCs in order to extract the lifetime distribution directly. The rate distribution has a half width of ~?0.5 decades and mainly resembles a somewhat high-frequency-skewed lognormal function. The combination of TRS and FRS methods appear best suited to uncovering the luminescence dynamics of NC materials having a broad emission spectrum. 相似文献