全文获取类型
收费全文 | 5071篇 |
免费 | 312篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 49篇 |
综合类 | 1篇 |
化学工业 | 1652篇 |
金属工艺 | 208篇 |
机械仪表 | 129篇 |
建筑科学 | 126篇 |
矿业工程 | 17篇 |
能源动力 | 152篇 |
轻工业 | 727篇 |
水利工程 | 21篇 |
石油天然气 | 18篇 |
无线电 | 218篇 |
一般工业技术 | 1108篇 |
冶金工业 | 140篇 |
原子能技术 | 63篇 |
自动化技术 | 761篇 |
出版年
2023年 | 57篇 |
2022年 | 98篇 |
2021年 | 207篇 |
2020年 | 143篇 |
2019年 | 160篇 |
2018年 | 225篇 |
2017年 | 223篇 |
2016年 | 260篇 |
2015年 | 191篇 |
2014年 | 244篇 |
2013年 | 507篇 |
2012年 | 279篇 |
2011年 | 315篇 |
2010年 | 278篇 |
2009年 | 251篇 |
2008年 | 166篇 |
2007年 | 116篇 |
2006年 | 89篇 |
2005年 | 65篇 |
2004年 | 56篇 |
2003年 | 65篇 |
2002年 | 54篇 |
2001年 | 50篇 |
2000年 | 41篇 |
1999年 | 38篇 |
1998年 | 46篇 |
1997年 | 43篇 |
1996年 | 51篇 |
1995年 | 44篇 |
1994年 | 47篇 |
1993年 | 44篇 |
1992年 | 32篇 |
1991年 | 27篇 |
1988年 | 22篇 |
1987年 | 31篇 |
1986年 | 26篇 |
1985年 | 42篇 |
1984年 | 44篇 |
1983年 | 45篇 |
1982年 | 54篇 |
1981年 | 42篇 |
1980年 | 46篇 |
1979年 | 43篇 |
1978年 | 42篇 |
1977年 | 45篇 |
1976年 | 47篇 |
1975年 | 43篇 |
1974年 | 42篇 |
1973年 | 46篇 |
1971年 | 25篇 |
排序方式: 共有5390条查询结果,搜索用时 15 毫秒
91.
92.
This paper provides an overview of various existing approaches to automated formal analysis and verification. The most space is devoted to the approach of model checking, including its basic principles as well as the different techniques that have been proposed for dealing with the state space explosion problem in model checking. This paper, however, includes a brief discussion of theorem proving and static analysis too. All of the discussed approaches are introduced mostly on an informal level, with an attempt to provide the reader with their basic ideas and references to works where more details can be found. 相似文献
93.
Determination of L3 subshell X-ray production cross-sections and fluorescence yields of Pb, Th and U
nder
im
ek 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2000,170(3-4):293-298
A study of L3 subshell X-ray production cross-sections and fluorescence yields by using characteristic K X-rays as the exciting radiation is described. Only the L3 subshells of Pb, Th and U were excited by the characteristic K X-rays of the elements used as secondary sources. The cross-sections for the production of Ll, L and Lβ groups of L3 subshell X-rays of Pb, Th and U have been measured using photoionization by Rb, Nb and Mo K X-rays. The measured L3 X-ray production cross-section values for Pb, Th and U are in good agreement with the theoretical ones evaluated using L3 subshell fluorescence yield ω3, fractions of the radiative width F3i and L3 subshell photoionization cross-section σ3. The L3 subshell fluorescence yields (ω3) have also been computed using the presently measured cross-section values and the theoretical L3 subshell photoionization cross-section values. These results are compared with the theoretically predicted values. 相似文献
94.
Karolina Maciejewska Kamila Czarnecka Pawe Krcisz Dorota Niedziaek Grzegorz Wieczorek Robert Skibiski Pawe Szymaski 《International journal of molecular sciences》2022,23(11)
A series of new cyclopentaquinoline derivatives with 9-acridinecarboxylic acid and a different alkyl chain length were synthesized, and their ability to inhibit cholinesterases was evaluated. All designed compounds, except derivative 3f, exhibited a selectivity for butyrylcholinesterase (BuChE) with IC50 values ranging from 103 to 539 nM. The 3b derivative revealed the highest inhibitory activity towards BuChE (IC50 = 103.73 nM) and a suitable activity against AChE (IC50 = 272.33 nM). The 3f derivative was the most active compound to AChE (IC50 = 113.34 nM) with satisfactory activity towards BuChE (IC50 = 203.52 nM). The potential hepatotoxic effect was evaluated for both 3b and 3f compounds. The 3b and 3f potential antioxidant activity was measured using the ORAC-FL method. The 3b and 3f derivatives revealed a significantly higher antioxidant potency, respectively 35 and 25 higher than tacrine. Theoretical, physicochemical, and pharmacokinetic properties were calculated using ACD Labs Percepta software. Molecular modeling and kinetic study were used to reveal the mechanism of cholinesterase inhibition in the most potent compounds: 3b and 3f. 相似文献
95.
Karolina Dydak Adam Junka Grzegorz Nowacki Justyna Paleczny Patrycja Szymczyk-Zikowska Aleksandra Grzyska Olga Anioek Marzenna Bartoszewicz 《International journal of molecular sciences》2022,23(9)
Hernia repairs are the most common abdominal wall elective procedures performed by general surgeons. Hernia-related postoperative infective complications occur with 10% frequency. To counteract the risk of infection emergence, the development of effective, biocompatible and antimicrobial mesh adjuvants is required. Therefore, the aim of our in vitro investigation was to evaluate the suitability of bacterial cellulose (BC) polymer coupled with gentamicin (GM) antibiotic as an absorbent layer of surgical mesh. Our research included the assessment of GM-BC-modified meshes’ cytotoxicity against fibroblasts ATCC CCL-1 and a 60-day duration cell colonisation measurement. The obtained results showed no cytotoxic effect of modified meshes. The quantified fibroblast cells levels resembled a bimodal distribution depending on the time of culturing and the type of mesh applied. The measured GM minimal inhibitory concentration was 0.47 µg/mL. Results obtained in the modified disc-diffusion method showed that GM-BC-modified meshes inhibited bacterial growth more effectively than non-coated meshes. The results of our study indicate that BC-modified hernia meshes, fortified with appropriate antimicrobial, may be applied as effective implants in hernia surgery, preventing risk of infection occurrence and providing a high level of biocompatibility with regard to fibroblast cells. 相似文献
96.
Tomáš Brázdil Javier Esparza Stefan Kiefer Antonín Kučera 《Formal Methods in System Design》2013,43(2):124-163
The paper gives a summary of the existing results about algorithmic analysis of probabilistic pushdown automata and their subclasses. 相似文献
97.
Renaldas Raišutis Rymantas Kažys Egidijus Žukauskas Liudas Mažeika 《NDT & E International》2011,44(7):645-654
In aerospace industry, one of the most important parts of gliders and motor-gliders is a lightweight longeron reinforcement made of carbon fibre reinforced plastics (CFRP) rods, known as Graphlite SM315 composite. During manufacturing, the rods as constructional elements are glued together in epoxy-filled matrix in order to build the arbitrary spar profile. The defects present in single rods such as breakage of fibres, multiple delaminations due to the lack of bonding between fibres and reduction in density affect essentially the strength and the fail-safety of the overall construction.The aim of the present work is to investigate the effects (transmission, reflection, scattering and mode conversion) of guided waves propagation along a square-shape CFRP rod in the case of contactless excitation/reception and interaction with region of multiple delaminations applying the numerical model and performing experiments.The square-shape CFRP composite rods possessing internal artificial delamination type defects have been investigated by numerical modelling and experiments employing the developed air-coupled technique (pitch-catch set-up) for cases of conventional transmission and advanced back-scattering configurations. Numerical predictions of guided wave interaction with a multiple delamination type defect in a CFRP composite rod have been made and the interaction mechanism explained. It is possible to conclude, that the actual sizes of the internal defects have been clearly detected using reception of the back-scattered waves over the edges of the defective regions only. 相似文献
98.
The results of investigation of the I–V characteristics are presented for asymmetrically necked n-Si samples. It is established that the asymmetry of the I–V characteristic for the samples under investigation at the room and liquid-nitrogen temperatures in high electric fields is caused by the space-charge formation. At T = 78 K in the warm-electron region, the asymmetry of the I–V characteristic is caused by nonlocal relation between the electron mobility and the nonuniform electric-field intensity. It is found that the sample resistance at liquid-nitrogen temperature insignificantly increases after applying high electric-field pulses. The effect under observation is attributed to a decrease in the electron concentration in the necked section of the sample due to the redistribution of hot electrons between bulk and surface. 相似文献
99.
P. Kopčanský N. Tomašovičová M. Koneracká M. Timko V. Závišová A. Džarová J. Jadzyn E. Beaugnon X. Chaud 《International Journal of Thermophysics》2011,32(4):807-817
In this study, observations of structural transitions in ferronematics based on the thermotropic nematic 4-trans-4′-n-hexyl-cyclohexyl-isothiocyanato-benzene (6CHBT) are described. Droplets of the nematic phase in the isotropic phase were observed in solutions of nematogenic 6CHBT dissolved in phenyl isocyanate and 6CHBT dissolved in phenyl isocyanate and doped with magnetic particles of different shapes (nanorods and chain-like particles). Magneto-dielectric measurements of structural transitions in these new systems enable to estimate of the type of anchoring of the nematic molecules on the magnetic particles surface. 相似文献
100.