全文获取类型
收费全文 | 1439篇 |
免费 | 74篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 1514篇 |
出版年
2023年 | 18篇 |
2022年 | 105篇 |
2021年 | 94篇 |
2020年 | 45篇 |
2019年 | 35篇 |
2018年 | 48篇 |
2017年 | 41篇 |
2016年 | 62篇 |
2015年 | 30篇 |
2014年 | 75篇 |
2013年 | 101篇 |
2012年 | 84篇 |
2011年 | 119篇 |
2010年 | 100篇 |
2009年 | 73篇 |
2008年 | 77篇 |
2007年 | 61篇 |
2006年 | 40篇 |
2005年 | 44篇 |
2004年 | 24篇 |
2003年 | 30篇 |
2002年 | 20篇 |
2001年 | 11篇 |
2000年 | 17篇 |
1999年 | 23篇 |
1998年 | 9篇 |
1997年 | 20篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1514条查询结果,搜索用时 0 毫秒
101.
Koel Das Aditi Majumder Monica Siegenthaler Hans Keirstead M. Gopi 《The Visual computer》2011,27(12):1055-1069
Remyelination therapy is a state-of-the-art technique for treating spinal cord injury (SCI). Demyelination—the loss of myelin
sheath that insulates axons, is a prominent feature in many neurological disorders resulting in SCI. This lost myelin sheath
can be replaced by remyelination. In this paper, we propose an algorithm for efficient automated cell classification and visualization
to analyze the progress of remyelination therapy in SCI. Our method takes as input the images of the cells and outputs a density
map of the therapeutically important oligodendrocyte-remyelinated axons (OR-axons) which is used for efficacy analysis of
the therapy. Our method starts with detecting cell boundaries using a robust, shape-independent algorithm based on iso-contour
analysis of the image at progressively increasing intensity levels. The detected boundaries of spatially clustered cells are
then separated using the Delaunay triangulation based contour separation method. Finally, the OR-axons are identified and
a density map is generated for efficacy analysis of the therapy. Our efficient automated cell classification and visualization
of remyelination analysis significantly reduces error due to human subjectivity. We validate the accuracy of our results by
extensive cross-verification by the domain experts. 相似文献
102.
Integrated microfluidic system enabling (bio)chemical reactions with on-line MALDI-TOF mass spectrometry 总被引:2,自引:0,他引:2
Brivio M Fokkens RH Verboom W Reinhoudt DN Tas NR Goedbloed M van den Berg A 《Analytical chemistry》2002,74(16):3972-3976
A continuous flow micro total analysis system (micro-TAS) consisting of an on-chip microfluidic device connected to a matrix assisted laser desorption ionization [MALDI] time-of-flight [TOF] mass spectrometer (MS) as an analytical screening system is presented. Reaction microchannels and inlet/outlet reservoirs were fabricated by powderblasting on glass wafers that were then bonded to silicon substrates. The novel lab-on-a-chip was realized by integrating the microdevice with a MALDI-TOFMS standard sample plate used as carrier to get the microfluidic device in the MALDI instrument. A novel pressure-driven pumping mechanism using the vacuum of the instrument as a driving force induces flow in the reaction microchannel in a self-activating way. Organic syntheses as well as biochemical reactions are carried out entirely inside the MALDI-MS ionization vacuum chamber and analyzed on-line by MALDI-TOFMS in real time. The effectiveness of the micro-TAS system has been successfully demonstrated with several examples of (bio)chemical reactions. 相似文献
103.
This article responds to a critique by H. C. Barrett, D. A. Frederick, M. G. Haselton, and R. Kurzban (see record 2006-10940-009), wherein it is argued that manipulations of cognitive constraints cannot be used to test general evolutionary hypotheses regarding the architecture of mind. In making this argument, Barrett et al. focus on what they believe to be faulty logic in D. DeSteno, M. Y. Bartlett, J. Braverman, and P. Salovey's (see record 2002-18731-006) use of such techniques to examine proposed sex differences in jealousy. In presenting their argument, however, Barrett et al. appear to disregard central findings presented in DeSteno et al. (2002) and, in so doing, fail to grasp the interrelations among findings that might readily address their concerns. Here, the authors present arguments for why and when manipulations of cognitive resources may prove useful in investigating evolved psychological mechanisms and, in so doing, situate their use within the ongoing debate concerning evolved sex differences in jealousy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
104.
A Dynamic Component and Aspect-Oriented Platform 总被引:1,自引:0,他引:1
105.
Monica Meijsing 《Minds and Machines》2006,16(4):443-461
It is widely accepted that embodiment is crucial for any self-aware agent. What is less obvious is whether the body has to be real, or whether a virtual body will do. In that case the notion of embodiment would be so attenuated as to be almost indistinguishable from disembodiment. In this article I concentrate on the notion of embodiment in human agents. Could we be disembodied, having no real body, as brains-in-a-vat with only a virtual body? Thought experiments alone will not suffice to answer this Cartesian question. I will draw on both philosophical arguments and empirical data on phantom phenomena. My argument will proceed in three steps. Firstly I will show that phantom phenomena provide a prima facie argument that real embodiment is not necessary for a human being. Secondly I will give a philosophical argument that real movement must precede the intention to move and to act. Agents must at least have had real bodies once. Empirical data seems to bear this out. Finally, however, I will show that a small number of aplasic phantom phenomena undermines this last argument. Most people must have had a real body. But for some people a partly virtual, unreal, phantom body seems to suffice. Yet though there is thus no knockdown argument that we could not be brains-in-a-vat, we still have good reasons to suppose that embodiment must be real, and not virtual. 相似文献
106.
Monica Sorescu A. Grabias L. Diamandescu D. Tarabasanu 《Journal of Materials Synthesis and Processing》2000,8(2):67-72
The collapse of the magnetic hyperfine structure of barium hexaferrite as an effect of mechanochemical activation was investigated. The various inequivalent sites and phases present in the milled material were studied by transmission Mössbauer spectroscopy. Barium hexaferrite nanoparticles were obtained after only 2 h of milling time and were found to coexist with iron oxide particles for longer times of exposure to mechanochemical activation. The milled samples were then subjected to thermal annealing, in order to test the reversibility of the collapse of the hyperfine structure. The thermal annealing performed (700°C, 1 h) was partly successful in restoring the magnetic hyperfine structure of milled hexaferrite. Complementary information was obtained using transmission electron microscopy (TEM) and electron diffraction (ED). 相似文献
107.
To determine pseudopterosin composition and concentration in colonies of Pseudopterogorgia elisabethae from the islands of San Andres and Providencia, we collected fragments of individual colonies at various sites and depth ranges around the islands. Chromatographic profiles of the polar fraction, particularly those obtained by HPLC-MS analyses, allowed us to recognize two different chemotypes. Chemotype 1 characterized samples from Providencia whereas chemotype 2 characterized samples from San Andres. A complex pseudopterosin mixture (compounds 1-13) characterized chemotype 1. These compounds were isolated by a combination of chromatographic methods and identified by spectroscopic methods (MS, UV, 1H, and 13C NMR). We identified the known pseudopterosins G and K and seco-pseudopterosin A. We also isolated and identified seven new compounds, pseudopterosins P-V, isomers of known pseudopterosins. Pseudopterosins G and K were found at concentrations ranging between 1 and 3% of the animal dry mass. Pseudopterosins Q and U were the major compounds reaching up to 6% of the animal dry mass at some locations. Major metabolites in chemotype 2 had a molecular weight and fragmentation pattern different from that observed in the pseudopterosins, as determined by HPLC-MS. Total pseudopterosin concentration in this chemotype was below 3% dry mass at all sites. Total pseudopterosin concentration was significantly higher in chemotype 1, with concentrations ranging between 4 and 20% dry mass. At most locations on Providencia, however, total pseudopterosin concentration ranged between 11 and 15% dry mass. Concentrations exceed reports from other locations in the Caribbean. Furthermore, pseudopterosin composition in our samples is quite different from those in specimens of P. elisabethae from the Bahamas and Bermuda. Pseudopterosins G, K, and P-V are characteristic of P. elisabethae colonies from the island of Providencia, while pseudopterosins A-D are characteristic of colonies of P. elisabethae from the Bahamas islands, and pseudopterosins E-L have been isolated from P. elisabethae from the Bahamas and Bermuda. The overall morphology of P. elisabethae can be variable, and chemical differences are not correlated to specific morphs. We confirmed the species identity of each colony by morphological and sclerite analysis and found no significant differences in sclerite dimensions among different colonies and chemotypes. 相似文献
108.
In this study, the atomic force microscope has been employed in force spectroscopy mode to gain information on the interaction between long mucin molecules and a positively charged surface during the first few seconds of interaction. Recent studies have revealed that negatively charged mucin molecules introduced to a positively charged surface are kinetically trapped and bind very rapidly, assuming non-equilibrium conformations. This systematic study of surface dwell times has revealed that significant differences exist in mucin adsorption during the first three seconds of introduction to the surface and provides direct evidence of molecular rearrangement for several seconds before trapping occurs. Limited interactions were recorded at dwell times of less than one second, with increased molecular rearrangement observed between 1.5 and 2.25 s. Increasing the surface dwell time beyond this critical limit caused rupture of the tip-tethered mucin molecules during the retract cycle of the cantilever. All subsequent recorded events, at increased dwell times up to 3 s, revealed events at much reduced distances from the point of contact between the mucin functionalised-cantilever and the positively charged surface. 相似文献
109.
Assessing blood flow control through a bootstrap method 总被引:2,自引:0,他引:2
Simpson DM Panerai RB Ramos EG Lopes JM Marinatto MN Nadal J Evans DH 《IEEE transactions on bio-medical engineering》2004,51(7):1284-1286
In order to assess blood flow control, the relationship between blood pressure and blood flow can be modeled by linear filters. We present a bootstrap method, which allows the statistical analysis of an index of blood flow control that is obtained from constrained system identification using an established set of pre-defined filters. 相似文献
110.
A new procedure is presented for determining in situ the solar calibration constant, i.e., the Sun-sky radiometer counts for a direct normal solar flux extrapolated to the top of the atmosphere. The method makes use of a modified version of the Langley plot based on the use of an inversion code of column-integrated aerosol size distribution, and it is ordinarily applied to calibrate Prede Sun-sky radiometers. To analyze how such an in situ method can work accurately, the technique has been applied to a five-month dataset obtained from measurements taken in Rome, Italy, by a Prede Sun-sky radiometer from 22 April to 5 November 2001. The precision of the in situ method has been estimated to within 1-2.5%, depending on the wavelength. 相似文献