全文获取类型
收费全文 | 592篇 |
免费 | 26篇 |
专业分类
电工技术 | 11篇 |
化学工业 | 160篇 |
金属工艺 | 17篇 |
机械仪表 | 7篇 |
建筑科学 | 21篇 |
能源动力 | 29篇 |
轻工业 | 55篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 56篇 |
一般工业技术 | 103篇 |
冶金工业 | 88篇 |
原子能技术 | 5篇 |
自动化技术 | 62篇 |
出版年
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 20篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 12篇 |
2015年 | 15篇 |
2014年 | 9篇 |
2013年 | 27篇 |
2012年 | 35篇 |
2011年 | 37篇 |
2010年 | 27篇 |
2009年 | 29篇 |
2008年 | 46篇 |
2007年 | 25篇 |
2006年 | 24篇 |
2005年 | 31篇 |
2004年 | 23篇 |
2003年 | 14篇 |
2002年 | 13篇 |
2001年 | 14篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 35篇 |
1997年 | 14篇 |
1996年 | 14篇 |
1995年 | 13篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 10篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有618条查询结果,搜索用时 15 毫秒
81.
82.
Fully quantitative analyses of DRIFTS data are required when the surface concentrations and the specific rate constants of reaction (or desorption) of adsorbates are needed to validate microkinetic models. The relationship between the surface coverage of adsorbates and various functions derived from the signal collected by DRIFTS is discussed here. The Kubelka-Munk and pseudoabsorbance (noted here as absorbance, for the sake of brevity) transformations were considered, since those are the most commonly used functions when data collected by DRIFTS are reported. Theoretical calculations and experimental evidence based on the study of CO adsorption on Pt/SiO2 and formate species adsorbed on Pt/CeO2 showed that the absorbance (i.e., = log 1/R', with R' = relative reflectance) is the most appropriate, yet imperfect, function to give a linear representation of the adsorbate surface concentration in the examples treated here, for which the relative reflectance R' is typically > 60%. When the adsorbates lead to a strong signal absorption (e.g., R' < 60%), the Kubelka-Munk function is actually more appropriate. The absorbance allows a simple correction of baseline drifts, which often occur during time-resolved data collection over catalytic materials. Baseline corrections are markedly more complex in the case of the other mathematical transforms, including the function proposed by Matyshak and Krylov (Catal. Today 1995, 25, 1-87), which has been proposed as an appropriate representation of surface concentrations in DRIFTS spectroscopy. 相似文献
83.
Mazel V Richardin P Debois D Touboul D Cotte M Brunelle A Walter P Laprévote O 《Analytical chemistry》2007,79(24):9253-9260
A new protocol is implemented to demonstrate the presence of blood in the patina of African art objects from Mali. Divided into three steps, the protocol first consists in demonstrating the presence of proteins and localizing them in the sample's cross sections using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and synchrotron-based infrared microspectrometry (microFT-IR). In a second time, TOF-SIMS is used to investigate heme, which is a blood marker. If heme is missing, which could mean that it is too degraded to be detected, X-ray microfluorescence (microXRF) and X-ray absorption near-edge microspectroscopy (microXANES) are used to prove the presence of iron in the protein area and to get a fingerprint of its chemical environment. This permits us thus to demonstrate that iron is indeed linked with proteins and not with mineral phases of the sample. Coupled with the ritual context of the objects, this constitutes a proof of the use of blood. Thanks to this protocol, which has the major advantage of avoiding false positive results, the presence of blood has been demonstrated in seven out of the eight studied samples. 相似文献
84.
Wissam Rached Frderic Sicard Alain Lafargue Delphine Thorel 《International Journal of Refrigeration》2007,30(8):1393-1400
Ice slurries are used in indirect refrigeration systems. The storage tank of ice slurry systems decreases the maximum required cooling capacity of the equipment and smooths down the installation consumption. An advantage of ice slurry systems compared to chilled water systems is the higher cooling energy that can be delivered to customers using the same installed pipes. This paper gives a complete investigation of ice slurry pressure drops and deposition velocity. A model for the friction factor, obtained by empirical and semi-empirical approximation, is discussed. A new simple and efficient method is introduced to find the deposition velocity in an ice slurry fluid flow. Finally a variety of experimental results and some theoretical calculations of ice slurry flow patterns are shown. 相似文献
85.
Topham CM; Mouledous L; Poda G; Maigret B; Meunier JC 《Protein engineering, design & selection : PEDS》1998,11(12):1163-1179
The opioid receptor like (ORL1) receptor is a G-protein coupled receptor
superfamily, and regulates a plethora of neurophysiological functions. The
structural requirements for receptor activation by its endogenous agonist,
nociceptin (FGGFTGARKSARKLANQ), differ markedly from those of the
kappa-opioid receptor and its putative peptide agonist, dynorphin A
(YGGFLRRIRPKLKWDNQ). In order to probe the functional architecture of the
ORL1 receptor, a molecular model of the receptor has been built, including
the TM domain and the extra- and intracellular loops. An extended binding
site able to accommodate nociceptin-(1-13), the shortest fully active
analogue of nociceptin, has been characterized. The N-terminal FGGF
tetrapeptide is proposed to bind in a highly conserved region, comprising
two distinct hydrophobic pockets in a cavity formed by TM helices 3, 5, 6
and 7, capped by the acidic second extracellular (EL2) loop controlling
access to the TM elements of the peptide binding site. The nociceptin
conformation provides for the selective preference of the ORL1 receptor for
nociceptin over dynorphin A, conferred by residue positions 5 and 6 (TG
versus LR), and the favourable interaction of its highly positively charged
core (residues 8-13) with the EL2 loop, thought to mediate receptor
activation. The functional roles of the EL2 loop and the conserved
N-terminal tetrapeptide opioid 'message' binding site are discussed in the
context of the different structural requirements of the ORL1 and
kappa-opioid receptors for activation.
相似文献
86.
Luke Mansard David Baux Christel Vach Catherine Blanchet Isabelle Meunier Marjolaine Willems Valrie Faugre Corinne Baudoin Melody Moclyn Julie Bianchi Helene Dollfus Brigitte Gilbert-Dussardier Delphine Dupin-Deguine Dominique Bonneau Isabelle Drumare Sylvie Odent Xavier Zanlonghi Mireille Claustres Michel Koenig Vasiliki Kalatzis Anne-Franoise Roux 《International journal of molecular sciences》2021,22(24)
Usher syndrome is an autosomal recessive disorder characterized by congenital hearing loss combined with retinitis pigmentosa, and in some cases, vestibular areflexia. Three clinical subtypes are distinguished, and MYO7A and USH2A represent the two major causal genes involved in Usher type I, the most severe form, and type II, the most frequent form, respectively. Massively parallel sequencing was performed on a cohort of patients in the context of a molecular diagnosis to confirm clinical suspicion of Usher syndrome. We report here 231 pathogenic MYO7A and USH2A genotypes identified in 73 Usher type I and 158 Usher type II patients. Furthermore, we present the ACMG classification of the variants, which comprise all types. Among them, 68 have not been previously reported in the literature, including 12 missense and 16 splice variants. We also report a new deep intronic variant in USH2A. Despite the important number of molecular studies published on these two genes, we show that during the course of routine genetic diagnosis, undescribed variants continue to be identified at a high rate. This is particularly pertinent in the current era, where therapeutic strategies based on DNA or RNA technologies are being developed. 相似文献
87.
88.
Coton E Coton M Levert D Casaregola S Sohier D 《International journal of food microbiology》2006,108(1):130-135
In this study, rDNA ITS restriction analysis was used to identify yeasts from two naturally fermented products: French ciders and black olives. In cider musts and bottled ciders, the PCR-RFLP method generated 15 different ITS/RFLP profiles for a total of 208 isolates. The predominant yeasts corresponded to Saccharomyces bayanus, Saccharomyces cerevisiae, Lachancea cidri and Dekkera anomala. Three identified species: Candida sake, Candida tropicalis and Kluyveromyces marxianus had never been described before in ciders. For the black olive fermentation, the method allowed for identification of 11 profiles for a total of 137 isolates. A sequential apparition of yeasts was observed with Pichia anomala, Candida boidinii and Debaryomyces etchellsii being the predominant species. Four isolates did not correspond to any known species based on the sequencing of the D1/D2 region of the 26S rRNA gene. By using the rDNA ITS method, valuable information on yeast population biodiversity and dynamics in the naturally fermented food products studied was obtained. 相似文献
89.
Si-based surface plasmon resonance (SPR) in the Kretschmann-Raether geometry is considered as a platform for the optical measurement of high refractive index films. The implementation of the SPR effect becomes possible due to the relatively high index of refraction of Si compared to most materials. As examples we study the SPR responses for some important semiconductor-based films, including laser-ablated porous silicon and thin germanium films. Using SPR data, we determine the refractive indices of these films for different parameters (thickness and porosity) and ambiences. We also discuss novel SPR biosensor architectures with the use of these solid films. 相似文献
90.
Rapp D Potier P Jocteur-Monrozier L Richaume A 《Environmental science & technology》2006,40(20):6324-6329
This study is part of a European project focused on understanding the biotic and abiotic mechanisms involved in the retention and dissemination of transmissible spongiform encephalopathies (TSE) infectivity in soil in order to propose practical recommendations to limit environmental contamination. A 1-year field experiment was conducted with lamb carcasses buried in a pasture soil at three depths (25, 45, and 105 cm). Microbial community response to carcasses was monitored through the potential proteolytic activity and substrate induced respiration (SIR). Soil above carcasses and control soil exhibited low proteolytic capacity, whatever the depth of burial. Contrastingly, in soil beneath the carcasses, proteolysis was stimulated. Decomposing carcasses also stimulated SIR, i.e., microbial biomass, suggesting that proteolytic populations specifically developed on lixiviates from animal tissues. Decomposition of soft tissues occurred within 2 months at subsurface while it lasted at least 1 year at deeper depth where proteolytic activities were season-dependent. The ability of soil proteases to degrade the beta form of prion protein was shown in vitro and conditions of burial relevant to minimize the risk of prion protein dissemination are discussed. 相似文献