全文获取类型
收费全文 | 298篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
综合类 | 1篇 |
化学工业 | 26篇 |
金属工艺 | 10篇 |
机械仪表 | 16篇 |
建筑科学 | 4篇 |
能源动力 | 2篇 |
轻工业 | 21篇 |
水利工程 | 5篇 |
无线电 | 12篇 |
一般工业技术 | 66篇 |
冶金工业 | 114篇 |
原子能技术 | 3篇 |
自动化技术 | 19篇 |
出版年
2022年 | 4篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2015年 | 2篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 12篇 |
2007年 | 16篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 39篇 |
1997年 | 24篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1970年 | 4篇 |
1969年 | 1篇 |
1967年 | 3篇 |
1966年 | 2篇 |
1961年 | 1篇 |
1957年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有303条查询结果,搜索用时 15 毫秒
61.
62.
Alexander Leube Imre Kovats Siegfried Wahl Wolfgang Sickenberger 《Contact lens & anterior eye》2017,40(6):394-400
Purpose
Pilot study to investigate the feasibility of an axis-free correction approach of regular astigmatism using soft, bifocal contact lenses (CL).Methods
The investigation covers an optical simulation and a pilot study for the assessment of visual performance (over refraction OR, monocular visual acuity VA). The power of the two zones was adjusted according to the power of the astigmatic meridians, individually. Subjective performance was assessed in 30 participants with a mean horizontal cylindrical component of J0 = ? 0.65 ± 1.29 D (cylinder from ?0.75 to ?4.00 DC). OR and VA were measured directly after fitting the CL, after one hour and after 5 days (3FUP).Results
Evaluating the modulation transfer function, CL increased the Strehl ratio by 10% and the transferred spatial frequency was improved from 6.6 cpd to 21.3 cpd. Analysis of Sturm’s interval revealed a residual astigmatism of DAst = 0.73 D. OR revealed a statistically significant reduction of spherical error between baseline and all follow up (ΔM = ?2.14 D, p < 0.001) and between the J0 from baseline to 3FUP (ΔJ0 = ?0.46 D, p = 0.04). Wearing the CL for 5 days did not result in a significant difference of VA (ΔVA3FUP = +0.01 logMAR, p = 0.99).Conclusion
Axis-free correction of astigmatism using bifocal CL resulted in reasonable performance based on computer simulation. Participants showed no clinically reduced visual acuity or contrast sensitivity. Further clinical studies are needed to show if this approach provides a good alternative to conventional astigmatic correction. 相似文献63.
Tanemura T Balram KC Ly-Gagnon DS Wahl P White JS Brongersma ML Miller DA 《Nano letters》2011,11(7):2693-2698
A novel type of multiple-wavelength focusing plasmonic coupler based on a nonperiodic nanoslit array is designed and experimentally demonstrated. An array of nanoslits patterned on a thin metal film is used to couple free-space light into surface plasmon polaritons (SPPs) and simultaneously focus different-wavelength SPPs into arbitrary predefined locations in the two-dimensional plane. We design and fabricate a compact triplexer on a glass substrate with an integrated silicon photodetector. The photocurrent spectra demonstrate that the incident light is effectively coupled to SPPs and routed into three different focal spots depending on the wavelength. The proposed scheme provides a simple method of building wavelength-division multiplexing and spectral filtering elements, integrated with other plasmonic and optoelectronic devices. 相似文献
64.
Comparative microbiological investigations on the storage of roundwood from four healthy spruce trees and 14 diseased trees (damage classes 1 to 3) by sprinkling, altogether, did not show a clear relation between microbial infection and damage class of the trees. The heartwood of all logs was nearly sterile. Presumably due to a failure during sprinkling the sapwood was stained, but without relation to the damage class, so that stain fungi, moulds, yeasts, bacteria and some Basidiomycetes were isolated. 相似文献
65.
66.
67.
Carl-Mattheis Wahl Constanze Schmidt Markus Hecker Nina D. Ullrich 《International journal of molecular sciences》2022,23(17)
Gap junctions and their expression pattern are essential to robust function of intercellular communication and electrical propagation in cardiomyocytes. In healthy myocytes, the main cardiac gap junction protein connexin-43 (Cx43) is located at the intercalated disc providing a clear direction of signal spreading across the cardiac tissue. Dislocation of Cx43 to lateral membranes has been detected in numerous cardiac diseases leading to slowed conduction and high propensity for the development of arrhythmias. At the cellular level, arrhythmogenic diseases are associated with elevated levels of oxidative distress and gap junction remodeling affecting especially the amount and sarcolemmal distribution of Cx43 expression. So far, a mechanistic link between sustained oxidative distress and altered Cx43 expression has not yet been identified. Here, we propose a novel cell model based on murine induced-pluripotent stem cell-derived cardiomyocytes to investigate subcellular signaling pathways linking cardiomyocyte distress with gap junction remodeling. We tested the new hypothesis that chronic distress, induced by rapid pacing, leads to increased reactive oxygen species, which promotes expression of a micro-RNA, miR-1, specific for the control of Cx43. Our data demonstrate that Cx43 expression is highly sensitive to oxidative distress, leading to reduced expression. This effect can be efficiently prevented by the glutathione peroxidase mimetic ebselen. Moreover, Cx43 expression is tightly regulated by miR-1, which is activated by tachypacing-induced oxidative distress. In light of the high arrhythmogenic potential of altered Cx43 expression, we propose miR-1 as a novel target for pharmacological interventions to prevent the maladaptive remodeling processes during chronic distress in the heart. 相似文献
68.
Biochemical-Technological Studies on Wet-Processing of Maize. Part 2. The Change in the Composition of Steeping Water During the Steeping Process. 1. The time, for which the steeping water stays in a countercurrent steeping battery of 8 tanks, is about 20 h and should not be regarded as the steeping time of maize. 2. The changes in the composition of steeping water (dry matter, SO2 content, nitrogen substances, reducing substances, mineral substances, lactic acid) have been examined in the normal technological steeping cycle (without interruption of maizemilling), during the 40–50 hours' milling break as well in a laboratory-one-tank system, and from this resulting indications as to the processes taking place within the maize grain have been obtained. From the interior of the grain, substances that have become soluble by secondary reactions (SO2, enzymes) get into the steeping water beside substances that have been present in soluble form from the very start. 相似文献
69.
70.
Chemical vapour deposition processes (CVD) can produce metastable fine-grained materials as well as epitaxial coatings and
can have a very large throwing power depending on the process parameters. Therefore, CVD is an prospective method to deposit
high-temperature superconducting materials withT
c⩾10 K. One of the first superconductors which were produced was Nb3Sn on tapes and single wires. This superconducting material is, however, today produced by metallurgical methods. Since the
detection of Nb3Ge, CVD has become for these coatings the main method of production for the following reasons: high deposition rates, possibility
to dope the material by addition of further doping gases to the CVD-process, continuous process. These coatings were deposited
on tapes. For the first time the large throwing power of the CVD process was utilized for the deposition of B1 -NbC
x
N
y
, on carbon fibre bundles. This opens the possibility to produce multifilamentary structures used for magnetic applications.
The structure of the coating can be varied by changing the gas properties, by addition of further gases, by an ultrasonic
field, by ignition of a gas discharge and by multi-layering. CVD could also be a prospective method for producing the new
class of superconductors withT
c⩾30 K. 相似文献