全文获取类型
收费全文 | 2296篇 |
免费 | 131篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 32篇 |
综合类 | 5篇 |
化学工业 | 640篇 |
金属工艺 | 62篇 |
机械仪表 | 37篇 |
建筑科学 | 196篇 |
矿业工程 | 5篇 |
能源动力 | 85篇 |
轻工业 | 191篇 |
水利工程 | 16篇 |
石油天然气 | 7篇 |
无线电 | 170篇 |
一般工业技术 | 449篇 |
冶金工业 | 115篇 |
原子能技术 | 12篇 |
自动化技术 | 408篇 |
出版年
2023年 | 29篇 |
2022年 | 54篇 |
2021年 | 79篇 |
2020年 | 48篇 |
2019年 | 68篇 |
2018年 | 53篇 |
2017年 | 56篇 |
2016年 | 88篇 |
2015年 | 89篇 |
2014年 | 109篇 |
2013年 | 163篇 |
2012年 | 138篇 |
2011年 | 198篇 |
2010年 | 103篇 |
2009年 | 133篇 |
2008年 | 144篇 |
2007年 | 134篇 |
2006年 | 105篇 |
2005年 | 83篇 |
2004年 | 85篇 |
2003年 | 53篇 |
2002年 | 60篇 |
2001年 | 31篇 |
2000年 | 36篇 |
1999年 | 30篇 |
1998年 | 28篇 |
1997年 | 23篇 |
1996年 | 28篇 |
1995年 | 23篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 15篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 17篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
排序方式: 共有2430条查询结果,搜索用时 10 毫秒
51.
52.
Jens Georg Kaufmann Marc P. Y. Desmulliez Yingtao Tian Dennis Price Mike Hughes Nadia Strusevich Chris Bailey Changqing Liu David Hutt 《Microsystem Technologies》2009,15(8):1245-1254
In this paper we propose an agitation method based on megasonic acoustic streaming to overcome the limitations in plating
rate and uniformity of the metal deposits during the electroplating process. Megasonic agitation at a frequency of 1 MHz allows
the reduction of the thickness of the Nernst diffusion layer to less than 600 nm. Two applications that demonstrate the benefits
of megasonic acoustic streaming are presented: the formation of uniform ultra-fine pitch flip-chip bumps and the metallisation
of high aspect ratio microvias. For the latter application, a multi-physics based numerical simulation is implemented to describe
the hydrodynamics introduced by the acoustic waves as they travel inside the deep microvias. 相似文献
53.
54.
55.
Jan Hcker Tevfik Onur Mente Alessandro Sala Andrea Locatelli Thomas Schmidt Jens Falta Sanjaya D. Senanayake Jan Ingo Flege 《Advanced Materials Interfaces》2015,2(18)
The interaction of molecular hydrogen with ceria is of important relevance for heterogeneous catalysis related to green chemistry and renewable energy. Here, the complex structural transformations of a well‐defined cerium oxide model catalyst are followed in situ and in real time when exposed to a reactive H2 environment. By using electron spectromicroscopy and diffraction with chemical and structural sensitivities, it is demonstrated that the transition from CeO2 to crystalline Ce2O3 occurs through a mixture of transient, coexisting phases on the nanoscale. The findings establish a clear relationship between structure and functionality for hydrogen dissociation over ceria(111), bearing profound implications on the nature of the reduction (Ce4+ → Ce3+) and mechanism for H2 scission. 相似文献
56.
均方根值——平均值检波器——一种脉冲干扰抑制效果更佳的新型CISPR加权检波器 总被引:1,自引:0,他引:1
Jens Medler 《安全与电磁兼容》2008,(2):89-91
阐述了加权的目的,给出了新型均方根值(RMS)——平均值(AV)检波器的加权特性评估和加权函数的定义。同时对使用准峰值和平均值检波方式所得到的测量结果与使用均方根值—平均值检波方式所得到的测量结果进行了比较。根据比较结果,提出了均方根值——平均值检波方式所对应的发射类测试限值的建议。 相似文献
57.
58.
Sandrine Baltzer Timur Bulatov Christopher Schmied Andreas Krmer Benedict-Tilman Berger Andreas Oder Ryan Walker-Gray Christin Kuschke Kerstin Zühlke Jenny Eichhorst Martin Lehmann Stefan Knapp John Weston Jens Peter von Kries Roderich D. Süssmuth Enno Klussmann 《International journal of molecular sciences》2022,23(2)
The cAMP-dependent aquaporin-2 (AQP2) redistribution from intracellular vesicles into the plasma membrane of renal collecting duct principal cells induces water reabsorption and fine-tunes body water homeostasis. However, the mechanisms controlling the localization of AQP2 are not understood in detail. Using immortalized mouse medullary collecting duct (MCD4) and primary rat inner medullary collecting duct (IMCD) cells as model systems, we here discovered a key regulatory role of Aurora kinase A (AURKA) in the control of AQP2. The AURKA-selective inhibitor Aurora-A inhibitor I and novel derivatives as well as a structurally different inhibitor, Alisertib, prevented the cAMP-induced redistribution of AQP2. Aurora-A inhibitor I led to a depolymerization of actin stress fibers, which serve as tracks for the translocation of AQP2-bearing vesicles to the plasma membrane. The phosphorylation of cofilin-1 (CFL1) inactivates the actin-depolymerizing function of CFL1. Aurora-A inhibitor I decreased the CFL1 phosphorylation, accounting for the removal of the actin stress fibers and the inhibition of the redistribution of AQP2. Surprisingly, Alisertib caused an increase in actin stress fibers and did not affect CFL1 phosphorylation, indicating that AURKA exerts its control over AQP2 through different mechanisms. An involvement of AURKA and CFL1 in the control of the localization of AQP2 was hitherto unknown. 相似文献
59.
Copetti MV Iamanaka BT Mororó RC Pereira JL Frisvad JC Taniwaki MH 《International journal of food microbiology》2012,155(3):158-164
The acidic characteristics of cocoa beans have influence on flavor development in chocolate. Cocoa cotyledons are not naturally acidic, the acidity comes from organic acids produced by the fermentative microorganisms which grow during the processing of cocoa. Different concentrations of these metabolites can be produced according to the fermentation practices adopted in the farms, which could affect the growth and ochratoxin A production by fungi. This work presents two independent experiments carried out to investigate the effect of some fermentation practices on ochratoxin A production by Aspergillus carbonarius in cocoa, and the effect of weak organic acids such as acetic, lactic and citric at different pH values on growth and ochratoxin A production by A. carbonarius and Aspergillus niger in culture media. A statistical difference (ρ<0.05) in the ochratoxin A level in the cured cocoa beans was observed in some fermentation practices adopted. The laboratorial studies demonstrate the influence of organic acids on fungal growth and ochratoxin A production, with differences according to the media pH and the organic acid present. Acetic acid was the most inhibitory acid against A. carbonarius and A. niger. From the point of view of food safety, considering the amount of ochratoxin A produced, fermentation practices should be conducted towards the enhancement of acetic acid, although lactic and citric acids also have an important role in lowering the pH to improve the toxicity of acetic acid. 相似文献
60.
Jens Weitkamp 《化学,工程师,技术》1982,54(2):101-107
Manufacture of light hydrocarbons from heavy oils – processes and developments . High quality crude oils are running short and their price continues to increase. At the same time there is a trend towards light petroleum products for use as transportation fuels or petrochemical raw materials. Consequently, the conversion of heavy oils, i.e., particularly distillation residues but also heavy oils from tar sands, is gaining increasing commercial importance. The cracking processes currently used in the refining industry are reviewed. Emphasis is placed on their application to metal-and asphaltene-containing heavy oils. Feed pretreatment by solvent deasphalting is discussed and the manufacture of syncrude from tar sands is considered. New developments for conversion of heavy oils are outlined. The future production of shale oil and of transportation fuels from oil shale is briefly treated. 相似文献