全文获取类型
收费全文 | 359篇 |
免费 | 18篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 61篇 |
金属工艺 | 10篇 |
机械仪表 | 8篇 |
建筑科学 | 8篇 |
能源动力 | 12篇 |
轻工业 | 41篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 14篇 |
一般工业技术 | 37篇 |
冶金工业 | 108篇 |
自动化技术 | 71篇 |
出版年
2023年 | 1篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 13篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 16篇 |
2012年 | 18篇 |
2011年 | 14篇 |
2010年 | 17篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 12篇 |
2006年 | 18篇 |
2005年 | 11篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 36篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 11篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有378条查询结果,搜索用时 0 毫秒
1.
We demonstrate, for the first time to our knowledge, that a fast coherent collision between two Kerr spatial solitons can give rise to a significant phase shift for both interacting beams. The maximal collision-induced phase shift ≈π rad takes place when the amplitudes of the solitons are equal (η1=η2) and the length of the interaction zone is comparable with a soliton phase period. Depending on the ratio η2/η1, and the collision angle between the solitons, the magnitude of the phase shift can be varied within a reasonable range, for example from 180° to 40°. The analysis of the effect performed by the finite-difference beam-propagation method has shown that it is insensitive to the initial phase difference between the incident beams (δi), even in the case when η 1≠η2. It has been demonstrated that the phenomenon can be used for all-optical three-soliton logic elements, which are capable of providing more than 3-dB signal amplification and possess bi -independent output characteristics 相似文献
2.
The Santa Amalia building in Barcelona is a block of six flats incorporating a duct by which ligth is sent to the kitchens - previously without natural ligthing- and also allows natural ventilation. Moreover, the passive solar gains obtained from the extensive glazed surfaces and the conservation of internal heat gains, along with a high degree of isulation, give energy saving of 68% for heating. 相似文献
3.
RM Mu?oz LA Pulpón M Yebra J Segovia M San Martín C Salas 《Canadian Metallurgical Quarterly》1998,17(11):801-806
The fibrinolytic capacity of patients with acute myocardial infarction (AMI) is known to be impaired. The primary regulatory element of the fibrinolytic system is plasminogen activator inhibitor (PAI). It has been previously observed that there are 2 peaks in the plasma PAI level of AMI patients at 4h and 16h after thrombolytic therapy with recombinant tissue plasminogen activator (rtPA). Lanoteplase/SUN9216 is a mutant tPA with a biological half-life longer than that of rtPA. Thrombolytic therapy with mutant tPA or rtPA was carried out consecutively in 21 patients with AMI (8 patients as the mutant tPA group, and 13 patients as the rtPA group). The recanalization time of the mutant tPA group was significantly faster than that of the rtPA group (16.1 +/- 3.9 min vs 39.6 +/- 4.8 min, p<0.01). The PAI activity at 4h after the initiation of thrombolysis was significantly lower in the mutant tPA group than in the rtPA group (8.74 +/- 5.46IU/L vs 26.74 +/- 3.35 IU/L, p<0.01). There was a one mild peak in serial plasma PAI activity levels 24h after the initiation of thrombolysis. The results suggest that thrombolytic therapy with mutant tPA reduced the impairment of fibrinolytic capacity. The mutant tPA gives faster recanalization and lower PAI activity after successful thrombolysis, compared with rtPA. 相似文献
4.
Z. Benzo T. Zoltan M. Murillo M. Quintal J. Salas E. Marcano C. Gómez 《Journal of the American Oil Chemists' Society》2006,83(5):401-405
An emulsion-based method was developed as an alternative for the introduction of oil-based samples into a graphite furnace
to produce a more rapid, precise, and accurate method of analysis. The combination of emulsion sampling and electrothermal
atomization for atomic absorption spectroscopy was developed and then applied to the determination of Ni and manganese in
neem oil from Venezuela. The optimal concentration of neem oil in the emulsion was 30 and 4% for Ni and Mn, respectively,
based on the metal concentration of the neem oil. The stability of the emulsion as a function of time was evaluated. The use
of aqueous calibration solutions and the accuracy attained using this method make it attractive for the analysis of oil samples.
The metal recovery was between 97 and 101%. Based on the emulsion method, the neem oil samples had 1.39 and 0.21 mg of Mn
and Ni per kg of oil, respectively. The wet digestion method indicated a Mn and Ni concentration in the neem oil sample of
1.42 and 0.24 mg/kg, respectively. 相似文献
5.
The objective of our research was to develop assistive technology for visually impaired people, with a high appreciation for the human potential to achieve, to learn, and to achieve goals. In this document, we describe a virtual white cane made of a combination of a Smartphone and a laser pointer. In our device, the laser pointer beam reflection is captured by the Smartphone camera. The distance from the virtual white cane to the reflection is computed through active triangulation. Then, a personalized vibration, the magnitude of which corresponds to distance, is generated in the Smartphone. In this way, the users receive information that could prevent collisions with obstacles in the environment. Our contributions include the development of a virtual white cane around a Smartphone and other off-the-shelf accessories and a methodology to provide personalized vibratory feedback to the user. Our experiments show that to navigate, our instrument is better option, in terms of travel time, that the use of the hands. However, the travel time is still better using a traditional white cane than our instrument. 相似文献
6.
Salas E 《Human factors》2008,50(3):351-353
As the new century began, I took over as editor of the journal. By all accounts I inherited a robust journal - thanks to my predecessor. I made little adjustments on process and expanded the Editorial Board to reflect important emerging topics in human factors. The journal I "inherited" was in good shape, and I hope I left it a little better. In this paper, I reflect on the state of our science after making over 500 decisions over eight years (four as editor and four as associate editor). My reflections include issues concerning our theories, methodologies, and practice. These are offered as food for thought and in the hope that as we all reflect on the state of our science, we strive to make it better, more robust, and more relevant and that it has a greater influence on the world we live in. Time will tell. 相似文献
7.
A novel complex formed by ruthenium (III) and the sequestering ligand 1,2-propylenediaminetetraacetic acid (PDTA) has been synthetized and characterized. The structure of the monomeric compound, studied by X-ray diffraction , shows an almost symmetric octahedral geometry around the metal ion, with two chlorine atoms in a cis conformation. The antitumour activity against a variety of murine and human cancers is reported. 相似文献
8.
9.
Jacobo Pardo-Seco Xabier Bello Alberto Gmez-Carballa Federico Martinn-Torres Jos Ignacio Muoz-Barús Antonio Salas 《International journal of molecular sciences》2022,23(21)
Establishing the timeframe when a particular virus was circulating in a population could be useful in several areas of biomedical research, including microbiology and legal medicine. Using simulations, we demonstrate that the circulation timeframe of an unknown SARS-CoV-2 genome in a population (hereafter, estimated time of a queried genome [QG]; tE-QG) can be easily predicted using a phylogenetic model based on a robust reference genome database of the virus, and information on their sampling dates. We evaluate several phylogeny-based approaches, including modeling evolutionary (substitution) rates of the SARS-CoV-2 genome (~10−3 substitutions/nucleotide/year) and the mutational (substitutions) differences separating the QGs from the reference genomes (RGs) in the database. Owing to the mutational characteristics of the virus, the present Viral Molecular Clock Dating (VMCD) method covers timeframes going backwards from about a month in the past. The method has very low errors associated to the tE-QG estimates and narrow intervals of tE-QG, both ranging from a few days to a few weeks regardless of the mathematical model used. The SARS-CoV-2 model represents a proof of concept that can be extrapolated to any other microorganism, provided that a robust genome sequence database is available. Besides obvious applications in epidemiology and microbiology investigations, there are several contexts in forensic casework where estimating tE-QG could be useful, including estimation of the postmortem intervals (PMI) and the dating of samples stored in hospital settings. 相似文献
10.
Reactions with N-Acylimino-dithiocarbonic-acid-diesters . Reactions of N-acylimino-dithiocarbonic-acid-S,S-diesters 1 with nucleophilic com-pounds present new possibilities to synthesize heterocycles. With amines 1a reacts by mono- and disubstitution, respectively, of methylthio-groups to isothioureas 2 and guanidines 3 , with 1,2-bi-nucleophilic arenes to benzoheterocycles 4 , with aliphatic diamines to imidazolidines 5 , pyrimidines 6 , diazepines 7 and the hexamethylene-diamine-derivatives 8. 1a reacts also with hydrazines to 1,2,4-triazoles 9 and with hydrazides to the thiosemicarbazones 10 or 1,3,4-oxadiazoles 11 . Heterocyclisations of 1 with guanidines, thiourea, salts of thiourea and amidines give the 1,3,5-triazines 12, 14, 15 and 16 . N-benzoyl-dithiocarbonic-acid-methylester -amid reacts with CH-acidic compounds to thiazoles 17 . The structures of the final products are determined by i.r.-, 1H-n.m.r.-, u.v.- and mass-spectras. 相似文献