全文获取类型
收费全文 | 207篇 |
免费 | 12篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 26篇 |
金属工艺 | 6篇 |
机械仪表 | 3篇 |
建筑科学 | 18篇 |
矿业工程 | 6篇 |
能源动力 | 1篇 |
轻工业 | 16篇 |
水利工程 | 3篇 |
无线电 | 26篇 |
一般工业技术 | 37篇 |
冶金工业 | 50篇 |
原子能技术 | 1篇 |
自动化技术 | 25篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 14篇 |
2012年 | 9篇 |
2011年 | 13篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 5篇 |
2007年 | 8篇 |
2006年 | 8篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 18篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有219条查询结果,搜索用时 62 毫秒
1.
Hydroazafullerene C59HN was studied by vibrational infra-red and Raman spectroscopy and its thermal stability was examined. Fingerprints modes were identified and unambiguously differentiate it from bisazafullerene. At 700 K full transformation to bisazafullerene occurred, while an intermediate metastable phase was identified at 540 K showing different spectra where the splitting of most of the lines is strongly reduced. 相似文献
2.
Pichler M. Stelzer A. Gulden P. Seisenberger C. Vossiek M. 《IEEE transactions on circuits and systems. I, Regular papers》2007,54(5):1006-1017
The synthesis of linear frequency sweeps or chirps is required, among others, in frequency-modulated continuous-wave radar systems for object position estimation. Low phase and frequency errors in sweeps with high bandwidth are a prerequisite for good accuracy and resolution, but, in certain applications where high measurement rates are desired, the additional demand for short sweep cycles has to be met. Transient phenomena in dynamic synthesizers as well as nonlinear system behavior usually cause unknown phase errors in the system output. For the class of phase-locked-loop (PLL)-based frequency synthesizers, a novel output phase-measurement method and dedicated circuitry are proposed that allow significant reduction of phase errors by adaptive input predistortion. The measurement procedure is implemented within the PLL control circuitry and does not require external equipment. The application of this method to PLL system identification and linearization of extremely short frequency sweeps is shown 相似文献
3.
B Schnyder K Frutig D Mauri-Hellweg A Limat N Yawalkar WJ Pichler 《Canadian Metallurgical Quarterly》1998,28(11):1412-1417
BACKGROUND: The incidence of skin rashes or erythema multiforme to sulfamethoxazole in exposed patients is about 3%. Among patients with acquired immunodeficiency syndrome the risk is approximately 10 times higher. The pathogenesis of these reactions and the reason for the increased frequency in HIV infections are not understood. OBJECTIVE: To investigate drug specific T-cell-mediated cytotoxicity in sulfamethoxazole- induced skin reactions. METHODS: Specific T-cell lines and T-cell clones generated from a donor who developed a skin rash to sulfamethoxazole were assessed with a standard 4 h 51Cr cytotoxicity assay in the presence or absence of soluble sulfamethoxazole. B lymphoblasts and keratinocytes with and without interferon gamma pretreatment were used as target cells. Selective blockers of FasL/Fas and perforin-mediated killing and immunostaining for perforin were used to evaluate the involvement of the different cytolytic pathways. RESULTS: CD4+ and CD8+ sulfamethoxazole specific T-cell clones showed a drug-specific and MHC-restricted cytotoxicity against autologous B lymphoblasts in the presence of soluble sulfamethoxazole. Keratinocytes, if pretreated with interferon gamma, were specifically killed predominantly by CD4+ T-cell clones. Specific T-cell clones of both CD4+ and CD8+ phenotype showed a strong immunoreactivity for perforin and the cytotoxicity was blocked by concanamycin A which suggests a perforin-mediated killing. CONCLUSION: Perforin-mediated killing of autologous keratinocytes in the presence of soluble sulfamethoxazole by drug-specific CD4+ lymphocytes may be a pathway for generalized drug-induced delayed skin reactions. The requirement of interferon gamma pretreatment of keratinocytes for efficient specific killing might explain the increased frequency of drug allergies in generalized viral infections like HIV, when interferon gamma levels are elevated. 相似文献
4.
A. Grüneis M.H. Rümmeli C. Kramberger A. Barreiro T. Pichler R. Pfeiffer H. Kuzmany T. Gemming B. Büchner 《Carbon》2006,44(15):3177-3182
We have synthesized double wall carbon nanotubes (DWNTs) with few defects and little amorphous carbon by hot wall chemical vapor deposition (CVD) of alcohol. Catalysts for the DWNT growth were made from cobalt and molybdenum acetates. Scanning electron microscopy, transmission electron microscopy, multi frequency resonance Raman spectroscopy and optical absorption spectroscopy were used for characterization of the product with regard to DWNT yield, the nanotube diameter distribution, defect concentration and amorphous carbon content. Base pressures lower than 1 × 10−5 mbar in the CVD reactor considerably suppress defects in the DWNTs. Optimized growth conditions for DWNT formation are presented. 相似文献
5.
This paper deals with the dynamics of jointed flexible structures in multibody simulations. Joints are areas where the surfaces of substructures come into contact, for example, screwed or bolted joints. Depending on the spatial distribution of the joint, the overall dynamic behavior can be influenced significantly. Therefore, it is essential to consider the nonlinear contact and friction phenomena over the entire joint. In multibody dynamics, flexible bodies are often treated by the use of reduction methods, such as component mode synthesis (CMS). For jointed flexible structures, it is important to accurately compute the local deformations inside the joint in order to get a realistic representation of the nonlinear contact and friction forces. CMS alone is not suitable for the capture of these local nonlinearities and therefore is extended in this paper with problem-oriented trial vectors. The computation of these trial vectors is based on trial vector derivatives of the CMS reduction base. This paper describes the application of this extended reduction method to general multibody systems, under consideration of the contact and friction forces in the vector of generalized forces and the Jacobian. To ensure accuracy and numerical efficiency, different contact and friction models are investigated and evaluated. The complete strategy is applied to a multibody system containing a multilayered flexible structure. The numerical results confirm that the method leads to accurate results with low computational effort. 相似文献
6.
Server‐side component models such as Enterprise JavaBeans (EJB) add powerful abstractions to the bare ‘business objects’ layer in order to support a clean separation of server‐side application logic from other concerns such as distribution, security, transaction management and persistence. An improved separation of concerns is also the main goal of aspect‐oriented programming (AOP). This paper compares the two approaches and reasons about the possibility of substituting (parts of) component models using AOP mechanisms. We conclude that AOP is a promising approach to eliminate important shortcomings of the container‐based component approach. However, our analysis of concrete aspect‐oriented languages shows that current AOP technology is not yet mature enough to supersede component models. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
7.
Maria Smolle Stefan Uranitsch Armin Gerger Martin Pichler Johannes Haybaeck 《International journal of molecular sciences》2014,15(8):13993-14013
The latest investigations of long non-coding RNAs (lncRNAs) have revealed their important role in human cancers. LncRNAs are larger than 200 nucleotides in length and fulfill their cellular purpose without being translated into proteins. Though the molecular functions of some lncRNAs have been elucidated, there is still a high number of lncRNAs with unknown or controversial functions. In this review, we provide an overview of different lncRNAs and their role in human cancers. In particular, we emphasize their importance in tumorigenesis of colorectal cancer, the third most common cancer worldwide. 相似文献
8.
Sandra Moser Erich Leitner Thomas J. Plocek Koenraad Vanhessche Harald Pichler 《Yeast (Chichester, England)》2020,37(1):163-172
The triterpenoid (+)-ambrein is the major component of ambergris, a coprolite of the sperm whale that can only be rarely found on shores. Upon oxidative degradation of (+)-ambrein, several fragrance molecules are formed, amongst them (−)-ambrox, one of the highest valued compounds in the perfume industry. In order to generate a Saccharomyces cerevisiae whole-cell biocatalyst for the production of (+)-ambrein, intracellular supply of the squalene was enhanced by overexpression of two central enzymes in the mevalonate and sterol biosynthesis pathway, namely the N-terminally truncated 3-hydroxy-3-methylglutaryl-CoA reductase 1 (tHMG) and the squalene synthase (ERG9). In addition, another key enzyme in sterol biosynthesis, squalene epoxidase (ERG1) was inhibited by an experimentally defined amount of the inhibitor terbinafine in order to reduce flux of squalene towards ergosterol biosynthesis while retaining sufficient activity to maintain cell viability and growth. Heterologous expression of a promiscuous variant of Bacillus megaterium tetraprenyl-β-curcumene cyclase (BmeTC-D373C), which has been shown to be able to catalyse the conversion of squalene to 3-deoxyachillol and then further to (+)-ambrein resulted in production of these triterpenoids in S. cerevisiae for the first time. Triterpenoid yields are comparable with the best microbial production chassis described in literature so far, the methylotrophic yeast Pichia pastoris. Consequently, we discuss similarities and differences of these two yeast species when applied for whole-cell (+)-ambrein production. 相似文献
9.
In this paper, a multiscale model for the prediction and, finally, optimization of mechanical (elastic) and thermal (heat conductivity) properties of porous building materials is presented. These technical composites are characterized by the increase of porous space in the respective material system, resulting in a reduction of Young’s modulus, on the one hand, and in an increase of the thermal insulation capacity, on the other hand, yielding either a load-carrying insulation material or a structural material with enhanced resistance to heat transfer. Determination of engineering properties within the proposed multiscale approach departs from the underlying material composition, on the one hand, and the intrinsic properties of the constituents, i.e., the material phases, on the other hand, employing homogenization techniques based on continuum micromechanics. 相似文献
10.
Matthias Engleder Dr. Tea Pavkov‐Keller Dr. Anita Emmerstorfer Altijana Hromic Sabine Schrempf Dr. Georg Steinkellner Dr. Tamara Wriessnegger Prof. Erich Leitner Dr. Gernot A. Strohmeier Dr. Iwona Kaluzna Dr. Daniel Mink Dr. Martin Schürmann Dr. Silvia Wallner Prof. Peter Macheroux Prof. Karl Gruber Dr. Harald Pichler 《Chembiochem : a European journal of chemical biology》2015,16(12):1730-1734
Hydratases provide access to secondary and tertiary alcohols by regio‐ and/or stereospecifically adding water to carbon‐carbon double bonds. Thereby, hydroxy groups are introduced without the need for costly cofactor recycling, and that makes this approach highly interesting on an industrial scale. Here we present the first crystal structure of a recombinant oleate hydratase originating from Elizabethkingia meningoseptica in the presence of flavin adenine dinucleotide (FAD). A structure‐based mutagenesis study targeting active site residues identified E122 and Y241 as crucial for the activation of a water molecule and for protonation of the double bond, respectively. Moreover, we also observed that two‐electron reduction of FAD results in a sevenfold increase in the substrate hydration rate. We propose the first reaction mechanism for this enzyme class that explains the requirement for the flavin cofactor and the involvement of conserved amino acid residues in this regio‐ and stereoselective hydration. 相似文献