全文获取类型
收费全文 | 4383篇 |
免费 | 309篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 46篇 |
综合类 | 1篇 |
化学工业 | 1180篇 |
金属工艺 | 121篇 |
机械仪表 | 130篇 |
建筑科学 | 92篇 |
矿业工程 | 8篇 |
能源动力 | 132篇 |
轻工业 | 913篇 |
水利工程 | 64篇 |
石油天然气 | 25篇 |
无线电 | 250篇 |
一般工业技术 | 710篇 |
冶金工业 | 443篇 |
原子能技术 | 31篇 |
自动化技术 | 559篇 |
出版年
2024年 | 25篇 |
2023年 | 50篇 |
2022年 | 157篇 |
2021年 | 254篇 |
2020年 | 163篇 |
2019年 | 205篇 |
2018年 | 220篇 |
2017年 | 219篇 |
2016年 | 195篇 |
2015年 | 143篇 |
2014年 | 184篇 |
2013年 | 292篇 |
2012年 | 291篇 |
2011年 | 291篇 |
2010年 | 205篇 |
2009年 | 226篇 |
2008年 | 188篇 |
2007年 | 168篇 |
2006年 | 130篇 |
2005年 | 108篇 |
2004年 | 75篇 |
2003年 | 78篇 |
2002年 | 64篇 |
2001年 | 58篇 |
2000年 | 58篇 |
1999年 | 54篇 |
1998年 | 150篇 |
1997年 | 88篇 |
1996年 | 70篇 |
1995年 | 48篇 |
1994年 | 46篇 |
1993年 | 32篇 |
1992年 | 26篇 |
1991年 | 14篇 |
1990年 | 12篇 |
1989年 | 23篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 15篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1976年 | 11篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 2篇 |
排序方式: 共有4705条查询结果,搜索用时 15 毫秒
31.
Kwiatkowska Marta Norman Gethin Parker David Santos Gabriel 《Formal Methods in System Design》2021,58(1-2):188-250
Formal Methods in System Design - Automated verification techniques for stochastic games allow formal reasoning about systems that feature competitive or collaborative behaviour among rational... 相似文献
32.
Carlos Laorden Igor Santos Borja Sanz Gonzalo Alvarez Pablo G. Bringas 《Electronic Commerce Research and Applications》2012,11(3):290-298
Spam has become a major issue in computer security because it is a channel for threats such as computer viruses, worms, and phishing. More than 86% of received e-mails are spam. Historical approaches to combating these messages, including simple techniques such as sender blacklisting or the use of e-mail signatures, are no longer completely reliable. Many current solutions feature machine-learning algorithms trained using statistical representations of the terms that most commonly appear in such e-mails. However, these methods are merely syntactic and are unable to account for the underlying semantics of terms within messages. In this paper, we explore the use of semantics in spam filtering by introducing a pre-processing step of Word Sense Disambiguation (WSD). Based upon this disambiguated representation, we apply several well-known machine-learning models and show that the proposed method can detect the internal semantics of spam messages. 相似文献
33.
S. Moehlecke H. A. Borges C. Santos A. R. Sweedler 《Journal of Low Temperature Physics》1988,70(5-6):449-457
The electrical resistivity of the A15 compound Nb100–x
Pt
x
(20x28.9) is measured as a function of compositionx from room temperature to the superconducting transition temperatureT
c
The residual resistivity 0 is observed to be nearly independent of composition on the Nb-rich side of stoichiometry, but strongly dependent on the Pt-rich side. A closeT
c
correlation with the resistivity sloped/dT at high temperatures and with the electronic specific heat coefficient , which are proportional to the superconducting coupling parameter , is noted. The results can be understood in terms of an order-disorder model. 相似文献
34.
35.
dos Santos Tiago G. Silva Antonio O. S. Pedrosa Anne M. G. Araujo Antonio S. Souza Marcelo J. B. 《Journal of Porous Materials》2021,28(3):919-928
Journal of Porous Materials - Catalysts of AlMCM-48 with different Si/Al molar rations were synthesized by modified hydrothermal method with respect to previous works. As a consequence, the... 相似文献
36.
Sofia Cotton Dylan Ferreira Janine Soares Andreia Peixoto Marta Relvas-Santos Rita Azevedo Paulina Piairo Lorena Diguez Carlos Palmeira Luís Lima Andr M. N. Silva Lúcio Lara Santos Jos Alexandre Ferreira 《International journal of molecular sciences》2021,22(4)
Esophageal cancer (EC) is a life-threatening disease, demanding the discovery of new biomarkers and molecular targets for precision oncology. Aberrantly glycosylated proteins hold tremendous potential towards this objective. In the current study, a series of esophageal squamous cell carcinomas (ESCC) and EC-derived circulating tumor cells (CTCs) were screened by immunoassays for the sialyl-Tn (STn) antigen, a glycan rarely expressed in healthy tissues and widely observed in aggressive gastrointestinal cancers. An ESCC cell model was glycoengineered to express STn and characterized in relation to cell proliferation and invasion in vitro. STn was found to be widely present in ESCC (70% of tumors) and in CTCs in 20% of patients, being associated with general recurrence and reduced survival. Furthermore, STn expression in ESCC cells increased invasion in vitro, while reducing cancer cells proliferation. In parallel, an ESCC mass spectrometry-based proteomics dataset, obtained from the PRIDE database, was comprehensively interrogated for abnormally glycosylated proteins. Data integration with the Target Score, an algorithm developed in-house, pinpointed the glucose transporter type 1 (GLUT1) as a biomarker of poor prognosis. GLUT1-STn glycoproteoforms were latter identified in tumor tissues in patients facing worst prognosis. Furthermore, healthy human tissues analysis suggested that STn glycosylation provided cancer specificity to GLUT1. In conclusion, STn is a biomarker of worst prognosis in EC and GLUT1-STn glycoforms may be used to increase its specificity on the stratification and targeting of aggressive ESCC forms. 相似文献
37.
Sara M. dos S. Pizzatto Fernando Otavio Pizzatto Elidio Angioletto Sabrina Arcaro Eduardo Junca Oscar R. Klegues Montedo 《International Journal of Applied Ceramic Technology》2021,18(5):1734-1742
The effects of porous ceramic plates on the thermal behavior of ventilated façades were evaluated, and the results are presented herein. Thermal behavior in a ventilated façade of specimens containing 40 wt% of lime mud and a firing temperature of 1100°C was evaluated and compared with a commercial porcelain ceramic tile, which was the reference material. An experimental apparatus was designed to evaluate the thermal performance of the studied ventilated façades. The results revealed that the ventilated façade composed of the studied porous ceramic tiles produced a greater reduction in temperature between the external environmental and the interior of a box representing a building (ΔT5) of 65.7°C, compared with the façade composed of the commercial porcelain ceramic tiles (ΔT5 = 56.0°C) and even the traditional façade (ΔT5 = 49.1°C). Thus, porous ceramic tiles based on byproducts are promising candidates for ventilated façade systems. 相似文献
38.
Tiago Santos Celso S. F. Gomes Luc Hennetier Vítor A. F. Costa Luís C. Costa 《International Journal of Applied Ceramic Technology》2021,18(5):1801-1813
Industrial competition and environmental concerns lead to the exploration of alternative and energy-efficient technologies for ceramic materials processing. The main objective of this work was to present microwave heating as a viable option for stoneware processing. Stoneware functional properties are presented and discussed, with emphasis on impact strength, water absorption, porosity, and color. Microstructure analyses show that microwave- and gas-fired samples have higher densifications than electrically fired samples. A relevant finding for processing conditions is that microwave firing requires temperatures approximately 100°C lower than those required by conventional firing. Microwave-fired samples’ rupture energies are approximately twice (0.57 ± 0.06 (J)) those of the reference samples (0.26 ± 0.03 (J)), and their water absorptions are approximately one-half (1.5% at 1170°C and 0.8% at 1190°C) of those of the reference samples (2.0%), whereas the water absorption of electrically fired samples at 1180°C has been estimated to be 7.5%. Color analysis also evidences a shift to lower microwave firing temperatures, what is attributed to the enhanced transformations promoted by microwave heating when comparing with the transformations promoted by conventional (gas or electric) heating. 相似文献
39.
采用CO2激光器在316L不锈钢表面获得了超薄的铜熔覆层,文中分析和讨论了激光熔覆工艺参数加激光功率,熔覆速度,离焦量以及送粉率等对熔覆层质量的影响,提出了熔覆工艺的优化方法,使铜层的熔覆厚度可控制在100μm之内,稀释率小于10%以及很小的热变形。 相似文献
40.
A. Santos P. Yustos A. Quintanilla G. Ruiz F. Garcia-Ochoa 《Applied catalysis. B, Environmental》2005,61(3-4):323-333
Catalytic wet oxidation of phenol as a model pollutant has been performed in a three phase fixed-bed reactor (FBR) by using a commercial catalyst based on copper oxide in order to analyze the variables affecting significantly the copper leaching. It has been found that temperature has an almost negligible influence in the range studied (70–160 °C). On the contrary, an important effect of the pH value was noticed. The copper leaching reduces when the pH of the solution fed to the reactor increases, being almost negligible at pH ≥ 5. Moreover, the composition of the reaction media also influences the leaching. Higher copper concentrations than those expected by the effect of the acid aqueous media have been measured in the reactor effluent when phenol, catechol, hydroquinone, p-benzoquinone and maleic acid are present in the reaction media. On the contrary, oxalic acid has a negative influence on the leaching, since it captures the copper in solution to form copper oxalate which precipitates on the catalyst surface. For a previously acidified medium, the acetic and formic acids do not have any other effect on the copper leaching. It has been also demonstrated that as copper in solution decreases, so does phenol conversion, because the homogeneous catalysis contributes significantly to the oxidation reactions even in fixed-bed reactors. 相似文献