全文获取类型
收费全文 | 473篇 |
免费 | 21篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 495篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 25篇 |
2012年 | 21篇 |
2011年 | 24篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 24篇 |
2007年 | 27篇 |
2006年 | 22篇 |
2005年 | 20篇 |
2004年 | 15篇 |
2003年 | 22篇 |
2002年 | 19篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 28篇 |
1997年 | 16篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1966年 | 1篇 |
1963年 | 2篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1960年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有495条查询结果,搜索用时 328 毫秒
1.
Germanovix W. O'Neill G. Toumazou C. Drakakis F.M. Kitney R.I. Lande T.S. 《Electronics letters》1998,34(11):1051-1052
A micropower tone-control circuit comprising two first-order log-domain filters and a subtractor built with MOS transistors in weak inversion is described. The tone-controller is capable of providing bass cut/boost and treble cut operations. This circuit is being used in new designs of a conventional (acoustic) hearing-aid and cochlear implant 相似文献
2.
It is shown that for delta-sigma (ΣΔ) frequency-to-digital conversion (FDC) there is no need for a ΣΔ modulator, since a limited FM signal itself may be considered as an asynchronous ΣΔ bit-stream. By feeding the limited FM signal directly to a sinc2 ΣΔ decimator, a triangularly weighted zero-crossing counter FDC is introduced, providing ΣΔ noise shaping. The results measured confirm the theory 相似文献
3.
Bengt Sundén Tor Sköldheden 《International Communications in Heat and Mass Transfer》1985,12(5):559-566
An experimental investigation of heat transfer and pressure drop from a new type of corrugated channels is presented. The investigation has been carried out for Reynolds numbers in the range of for one corrugated and one smooth channel. It is found that the heat transfer from the corrugated channel is up to 3.5 times higher than for the smooth one. The pressure drop is however large (5 – 6 times the value of a smooth channel) and it is suggested that the corrugation height and length should be altered in order to balance the increases in heat transfer and pressure drop. 相似文献
4.
The design, synthesis, and ribozyme inhibitory activity of a novel EDTA-aminoglycoside conjugate are reported. This affinity cleaving reagent is a noninnocent RNA binder: its RNA affinity, judged by its ability to inhibit the hammerhead ribozyme HH16, is different than the parent natural product and is markedly dependent on the oxidation state of the chelated metal ion. 相似文献
5.
Roberto Lande Immacolata Pietraforte Anna Mennella Raffaella Palazzo Francesca Romana Spinelli Konstantinos Giannakakis Francesca Spadaro Mario Falchi Valeria Riccieri Katia Stefanantoni Curdin Conrad Cristiano Alessandri Fabrizio Conti Loredana Frasca 《International journal of molecular sciences》2021,22(4)
LL37 acts as T-cell/B-cell autoantigen in Systemic lupus erythematosus (SLE) and psoriatic disease. Moreover, when bound to “self” nucleic acids, LL37 acts as “danger signal,” leading to type I interferon (IFN-I)/pro-inflammatory factors production. T-cell epitopes derived from citrullinated-LL37 act as better antigens than unmodified LL37 epitopes in SLE, at least in selected HLA-backgrounds, included the SLE-associated HLA-DRB1*1501/HLA-DRB5*0101 backgrounds. Remarkably, while “fully-citrullinated” LL37 acts as better T-cell-stimulator, it loses DNA-binding ability and the associated “adjuvant-like” properties. Since LL37 undergoes a further irreversible post-translational modification, carbamylation and antibodies to carbamylated self-proteins other than LL37 are present in SLE, here we addressed the involvement of carbamylated-LL37 in autoimmunity and inflammation in SLE. We detected carbamylated-LL37 in SLE-affected tissues. Most importantly, carbamylated-LL37-specific antibodies and CD4 T-cells circulate in SLE and both correlate with disease activity. In contrast to “fully citrullinated-LL37,” “fully carbamylated-LL37” maintains both innate and adaptive immune-cells’ stimulatory abilities: in complex with DNA, carbamylated-LL37 stimulates plasmacytoid dendritic cell IFN-α production and B-cell maturation into plasma cells. Thus, we report a further example of how different post-translational modifications of a self-antigen exert complementary effects that sustain autoimmunity and inflammation, respectively. These data also show that T/B-cell responses to carbamylated-LL37 represent novel SLE disease biomarkers. 相似文献
6.
Hilde Lea Lein Kjell Wiik Mari-ann Einarsrud Tor Grande Edgar Lara-curzio 《Journal of the American Ceramic Society》2006,89(9):2895-2898
Steady-state compressive creep rate of La0.5 Sr0.5 Fe0.5 Co0.5 O3−δ (LSFC) and La0.5 Sr0.5 CoO3−δ (LSC) is reported in the temperature region 900°–1050°C and stress range 5–28 MPa. The stress exponents for the two materials were 1.71±0.18 and 1.24±0.15, respectively. The activation energy for creep was considerably higher for LSC (619±56 kJ/mol) than for LSFC (392±28 kJ/mol). The grain size exponent for LSC was 1.28±0.14. Considerably higher creep rates were observed for both materials in N2 compared with air. Relaxation by creep of chemical-induced stresses in oxygen-permeable membranes is addressed, especially at low partial pressure of oxygen. 相似文献
7.
Lise T. Sagdahl Mari-Ann Einarsrud Tor Grande 《Journal of the European Ceramic Society》2006,26(16):3665-3673
The sintering properties of La1−xSrxFeO3−δ (x = 0.1, 0.25) mixed conductors have been investigated with particular emphasis on the effect of secondary phases due to cation non-stoichiometry (±5 mol% La excess and deficiency). Secondary phases, located at grain boundaries in cation non-stoichiometric materials, increased the sintering temperature compared to single-phase materials. Extensive swelling in final stage of sintering was observed in all materials, which resulted in micro-porous materials. The swelling was most pronounced in the phase pure and two-phase materials due to La-deficiency, while refractory secondary phases in La-excess materials inhibited both sintering, grain growth and swelling. In La-deficient materials, formation of molten secondary phases resulted in rapid swelling due to viscous flow. The present findings demonstrated the importance of controlling sintering temperature and time, as well as careful control of the cation stoichiometry of La1−xSrxFeO3−δ in order to achieve fully dense and homogenous La1−xSrxFeO3−δ ceramics. 相似文献
8.
Christian Schøning Tor Grande 《JOM Journal of the Minerals, Metals and Materials Society》2006,58(2):58-61
The infiltration of molten electrolyte and sodium is known to deteriorate the refractory in aluminum electrolysis. The mineralogical
changes due to reactions with molten fluorides have previously been described throughly, while the effect of sodium has not
been considered in detail. This paper presents an experimental study of the chemical stability of some refractory materials
in sodium-rich environments. The materials were exposed to sodium vapor at 800°C for 4 hours. The mineralogical transformations
and deterioration of the materials due to reactions with sodium were analyzed by x-ray diffraction and optical and electron
microscopy. 相似文献
9.
10.
Object-oriented design is an approach to systems development that proposes the use of system objects to build new systems and rebuild old ones. An important goal of object-oriented development is to change the nature of traditional software development from designing and writing models from scratch to building systems through the assembly of reusable software objects. This article discusses the productivity potential as well as the limitations of object-oriented systems development and makes recommendations for its use. 相似文献