首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   854篇
  免费   52篇
  国内免费   1篇
电工技术   7篇
化学工业   228篇
金属工艺   6篇
机械仪表   21篇
建筑科学   24篇
矿业工程   2篇
能源动力   17篇
轻工业   269篇
水利工程   3篇
石油天然气   14篇
无线电   49篇
一般工业技术   106篇
冶金工业   85篇
原子能技术   4篇
自动化技术   72篇
  2023年   2篇
  2022年   19篇
  2021年   40篇
  2020年   28篇
  2019年   20篇
  2018年   21篇
  2017年   17篇
  2016年   24篇
  2015年   23篇
  2014年   28篇
  2013年   50篇
  2012年   49篇
  2011年   65篇
  2010年   32篇
  2009年   60篇
  2008年   47篇
  2007年   52篇
  2006年   34篇
  2005年   32篇
  2004年   20篇
  2003年   20篇
  2002年   28篇
  2001年   13篇
  2000年   16篇
  1999年   10篇
  1998年   30篇
  1997年   17篇
  1996年   17篇
  1995年   12篇
  1994年   12篇
  1993年   3篇
  1992年   6篇
  1991年   4篇
  1990年   8篇
  1989年   5篇
  1988年   6篇
  1985年   4篇
  1984年   1篇
  1983年   5篇
  1982年   3篇
  1981年   3篇
  1979年   1篇
  1977年   4篇
  1976年   6篇
  1975年   1篇
  1974年   2篇
  1971年   1篇
  1970年   2篇
  1969年   1篇
  1967年   1篇
排序方式: 共有907条查询结果,搜索用时 31 毫秒
1.
2.
A microbubble-powered bioparticle actuator   总被引:4,自引:0,他引:4  
We present the results of a device that uses controllable microbubble actuation to manipulate bioparticles. In order to create a useful device for controlling the position of bioparticles, predictable microfluidic actuation is crucial. The goal of this project was to develop fundamental technology that can be used to manipulate single bioparticles (e.g., cells). We use a thermal bubble actuation method to accomplish this goal. Microbubbles have the advantages of relatively simple electronics and fabrication but can be difficult to control. In this paper, we describe two specific accomplishments: the use of micromachined nucleation cavities to precisely localize thermal bubbles and to achieve controllable bubble formation temperatures and bubble dissipation and the demonstration of controllable microbubbles in a new device for particle sorting.  相似文献   
3.
4.
In this article, we are combining minimization criteria in the colorant separation process for spectral color reproduction. The colorant separation is performed by inverting a spectral printer model: the spectral Yule‐Nielsen modified Neugebauer model. The inversion of the spectral printer model is an optimization operation in which a criterion is minimized at each iteration. The approach we proposed minimizes a criterion defined by the weighted sum of a spectral difference and a perceptual color difference. The weights can be tuned with a parameter α ∞ [0, 1]. Our goal is to decrease the spectral difference between the original data and its reproduction and also to consider perceptual color difference under different illuminant conditions. In order to find the best α value, we initially compare a pure colorimetric criterion and a pure spectral criterion for the reproduction, then we combine them. We perform four colorant separations: the first separation will minimize the 1976 CIELAB color difference where four illuminants are tested, the second separation will minimize an equally weighted summation of 1976 CIELAB color difference with the four illuminants tested independently, the third colorant separation will minimize a spectral difference, and the fourth colorant separation will combine a weighted sum of a spectral difference and one of the two first colorimetric differences previously introduced. This last colorant separation can be tuned with a parameter in order to emphasize on spectral or colorimetric difference. We use a six colorants printer with artificial inks for our experiments. The prints are simulated by the spectral Yule‐Nielsen modified Neugebauer model. Two groups of data are used for our experiments. The first group describes the data printed by our printing system, which is represented by a regular grid in colorant space of the printer and the second group describes the data which is not originally produced by our printing system but mapped to the spectral printer gamut. The Esser test chart and the Macbeth Color Checker test chart have been selected for the second group. Spectral gamut mapping of this data is carried out before performing colorant separation. Our results show improvement for the colorant separations combining a sum of 1976 CIELAB color difference for a set of illuminants and for the colorant separation combining a sum of 1976 CIELAB color difference and spectral difference, especially in the case of spectral data originally produced by the printer. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 494–504, 2008  相似文献   
5.
Broadly speaking, structural defects include all those changes affecting a structure so that its behaviour is no longer in keeping with its intended use characteristics or differs from the behaviour it was originally designed for. In recent years, damage recognition and location methods, relying on the measurement of parameters that are indicative of a structure's mechanical behaviour, have benefitted from the introduction of innovative approaches, which make it possible to process and correlate an unprecedented wealth of measurble data. The aim of this work is to illustrate the basic problems associated with the different methods used for structural identification (parametric and non-parametric, linear and non-linear, with known and unknown inputs, etc.) and to report on some interesting applications for civil structural diagnosis.  相似文献   
6.
Applied Intelligence - The17 Sustainable Development Goals (SDGs) established by the United Nations Agenda 2030 constitute a global blueprint agenda and instrument for peace and prosperity...  相似文献   
7.
The purpose of this article is to present an evolutionary model of the enablers and inhibitors affecting the implementation and sustainability of continuous improvement. With this aim, a qualitative study using the grounded theory was carried out. Interviews were conducted with managers responsible for continuous improvement in first‐tier suppliers in the automotive sector. As a result, two existing lines of research in the continuous improvement literature are synthesized: on one hand, the literature concerning the enablers and barriers associated with continuous improvement sustainability; and on the other, the literature concerning the evolutionary model. © 2011 Wiley Periodicals, Inc.  相似文献   
8.
The dynamics of aging encompass the topics "aging of society" and "coping with chronic illness". Both are discussed using data from a qualitative study on return to work after coronary artery bypass surgery. Data from the retrospective substudy reveal four forms of aging as biographical development toward early retirement, old-age retirement, or related stages. It emerges that the manner of aging is less influenced by medical rehabilitation or medical history, and more by the patient's occupation and socio-economic status. Case reports are used to show that social class is a facilitation context, but not a determining force, regarding the choice between postoperative retirement or return to work. The final section briefly discusses whether the findings concerning the dynamics of aging of the cohort operated on in the late 1970s apply also to that of the cohort operated on in the late 1980s; this is addressed using some data from the prospective sub-study.  相似文献   
9.
Circular RNAs (circRNAs) are a large class of RNAs with regulatory functions within cells. We recently showed that circSMARCA5 is a tumor suppressor in glioblastoma multiforme (GBM) and acts as a decoy for Serine and Arginine Rich Splicing Factor 1 (SRSF1) through six predicted binding sites (BSs). Here we characterized RNA motifs functionally involved in the interaction between circSMARCA5 and SRSF1. Three different circSMARCA5 molecules (Mut1, Mut2, Mut3), each mutated in two predicted SRSF1 BSs at once, were obtained through PCR-based replacement of wild-type (WT) BS sequences and cloned in three independent pcDNA3 vectors. Mut1 significantly decreased its capability to interact with SRSF1 as compared to WT, based on the RNA immunoprecipitation assay. In silico analysis through the “Find Individual Motif Occurrences” (FIMO) algorithm showed GAUGAA as an experimentally validated SRSF1 binding motif significantly overrepresented within both predicted SRSF1 BSs mutated in Mut1 (q-value = 0.0011). U87MG and CAS-1, transfected with Mut1, significantly increased their migration with respect to controls transfected with WT, as revealed by the cell exclusion zone assay. Immortalized human brain microvascular endothelial cells (IM-HBMEC) exposed to conditioned medium (CM) harvested from U87MG and CAS-1 transfected with Mut1 significantly sprouted more than those treated with CM harvested from U87MG and CAS-1 transfected with WT, as shown by the tube formation assay. qRT-PCR showed that the intracellular pro- to anti-angiogenic Vascular Endothelial Growth Factor A (VEGFA) mRNA isoform ratio and the amount of total VEGFA mRNA secreted in CM significantly increased in Mut1-transfected CAS-1 as compared to controls transfected with WT. Our data suggest that GAUGAA is the RNA motif responsible for the interaction between circSMARCA5 and SRSF1 as well as for the circSMARCA5-mediated control of GBM cell migration and angiogenic potential.  相似文献   
10.
Lasioglossin III (LL-III) is a cationic antimicrobial peptide derived from the venom of the eusocial bee Lasioglossum laticeps. LL-III is extremely toxic to both Gram-positive and Gram-negative bacteria, and it exhibits antifungal as well as antitumor activity. Moreover, it shows low hemolytic activity, and it has almost no toxic effects on eukaryotic cells. However, the molecular basis of the LL-III mechanism of action is still unclear. In this study, we characterized by means of calorimetric (DSC) and spectroscopic (CD, fluorescence) techniques its interaction with liposomes composed of a mixture of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-rac-phosphoglycerol (POPG) lipids as a model of the negatively charged membrane of pathogens. For comparison, the interaction of LL-III with the uncharged POPC liposomes was also studied. Our data showed that LL-III preferentially interacted with anionic lipids in the POPC/POPG liposomes and induces the formation of lipid domains. Furthermore, the leakage experiments showed that the peptide could permeabilize the membrane. Interestingly, our DSC results showed that the peptide-membrane interaction occurs in a non-disruptive manner, indicating an intracellular targeting mode of action for this peptide. Consistent with this hypothesis, our gel-retardation assay experiments showed that LL-III could interact with plasmid DNA, suggesting a possible intracellular target.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号