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   310篇
  免费   15篇
  国内免费   4篇
电工技术   31篇
综合类   2篇
化学工业   91篇
金属工艺   20篇
机械仪表   7篇
建筑科学   5篇
能源动力   9篇
轻工业   18篇
无线电   17篇
一般工业技术   50篇
冶金工业   11篇
原子能技术   1篇
自动化技术   67篇
  2023年   1篇
  2022年   5篇
  2021年   8篇
  2020年   5篇
  2019年   2篇
  2018年   9篇
  2017年   3篇
  2016年   4篇
  2015年   6篇
  2014年   5篇
  2013年   21篇
  2012年   16篇
  2011年   29篇
  2010年   11篇
  2009年   19篇
  2008年   15篇
  2007年   23篇
  2006年   13篇
  2005年   13篇
  2004年   12篇
  2003年   13篇
  2002年   11篇
  2001年   9篇
  2000年   4篇
  1999年   8篇
  1998年   4篇
  1997年   6篇
  1996年   8篇
  1995年   4篇
  1994年   6篇
  1993年   3篇
  1992年   3篇
  1991年   6篇
  1990年   1篇
  1989年   5篇
  1988年   5篇
  1987年   3篇
  1985年   1篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1978年   2篇
  1977年   1篇
  1965年   1篇
排序方式: 共有329条查询结果,搜索用时 31 毫秒
101.
The existing phases in BaxGd1-xMnO3 solid solution system (0≤x≤ 1) were studied by analyzing the detailed crystal structure of each composition from the results of the Rietveld method using powder X-ray diffraction data. For a small substitution of Ba for Gd (0≤x〈0. 1), the orthorhombic phase with a perovskite type structure (Pnma space group) was stably formed and this fact was supported by the electron diffraction data. There existed an intermediate phase of Ba0.33Gd0.67MnO3, which was characterized as the tetragonal phase with perovskite structure. The composition range of this phase was narrow and almost line compound. Between the regions of these phases, there existed two-phase region. There was also a two-phase region between the intermediate tetragonal phase and BaMnO3. Measurement of electrical conductivities of these orthorhombic solid solutions and tetragonal phases showed semiconducting behaviors for both phases and the existence of the phase transition at high temperature for the orthorhombic phase, The transition temperature decreased as the Ba content increased.  相似文献   
102.
Among various metal ion-exchanged zeolites, metal loading alumina, and oxides, iron ion-exchanged mordenite was the most active for the selective reduction of nitrogen monoxide to nitrogen by ethene in the presence of oxygen at the temperature as low as 473 K. The catalytic activities of iron ion-exchanged zeolites depended on the zeolite structure and the iron ion exchange level. The effects of the zeolite structure are in the order of MOR > FER > MFI > Y > LTL at 473 K. The activity of iron ion-exchanged mordenite increased with the increment in the exchange level and levelled off above about 60%.  相似文献   
103.
Yasuaki  Hidenori 《Automatica》2003,39(12):2149-2156
Randomized algorithms are proposed for solving parameter-dependent linear matrix inequalities and their computational complexity is analyzed. The first proposed algorithm is an adaptation of the algorithms of Polyak and Tempo [(Syst. Control Lett. 43(5) (2001) 343)] and Calafiore and Polyak [(IEEE Trans. Autom. Control 46 (11) (2001) 1755)] for the present problem. It is possible however to show that the expected number of iterations necessary to have a deterministic solution is infinite. In order to make this number finite, the improved algorithm is proposed. The number of iterations necessary to have a probabilistic solution is also considered and is shown to be independent of the parameter dimension. A numerical example is provided.  相似文献   
104.
This paper presents an improvement of Herbrand's theorem. We propose a method for specifying a subuniverse of the Herbrand universe of a clause set S for each argument of predicate symbols and function symbols in S. We prove that a clause set S is unsatisfiable if and only if there is a finite unsatisfiable set of ground instances of clauses of S that are derived by only instantiating each variable, which appears as an argument of predicate symbols or function symbols, in S over its corresponding argument's sub-universe of the Herbrand universe of S. Because such sub-universes are usually smaller (sometimes considerably) than the Herbrand universe of S, the number of ground instances may decrease considerably in many cases. We present an algorithm for automatically deriving the sub-universes for arguments in a given clause set, and show the correctness of our improvement. Moreover, we introduce an application of our approach to model generation theorem proving for non-range-restricted problems, show the range-restriction transformation algorithm based on our improvement and provide examples on benchmark problems to demonstrate the power of our approach.  相似文献   
105.
I—SATCHMORE:An Improvement of A—SATCHMORE   总被引:1,自引:1,他引:0       下载免费PDF全文
This paper presents an improvement of A-SATCHMORE (SATCHMORE with Availability).A-SATCHMORE incorporates relevancy testing and availability checking into SATCHMO to prune away irrelevant forward chaining.However ,considering every consequent atom of those non-Horn clauses being derivable,A-SATCHMORE may suffer from a potential explosion of the search space when some of such consequent atoms are actually underivable.This paper introduces a solution for this problem and shows its correctness.  相似文献   
106.
107.
Hidenori Kimura 《Automatica》1982,18(2):125-145
This paper is concerned with the synthesis of a high-gain feedback control, called perfect regulation (p.r.), for linear multivariable systems with external signals. The existence condition for p.r. is derived, in which the minimum phase property plays an essential role. The use of an observer is discussed for achieving p.r. under restricted state observation. Some asymptotically ideal feedback properties are demonstrated, such as the complete desensitization, the complete servo performance with decoupling and the complete disturbance rejection, which formulate the loop-tightness for multivariable systems. A design method for applying p.r. to non-minimum phase systems, called subperfect regulation (s.p.r.), is proposed based on the factorization of the plant transfer function matrix into the minimum phase part and the totally non-minimum phase part. It is a multivariable extension of a well-known design technique for scalar systems to overcome the difficulty of phase non-minimality. Computational procedures for p.r. and s.p.r. are discussed. An illustrative example is shown.  相似文献   
108.
The sensitivity of oligosaccharides in mass spectrometry lags far behind that of peptides. This is a critical factor in realizing the high-throughput analysis of posttranslational modifications in proteomics. We here described that hydrazide derivatives of cyanine dyes (Cy3, Cy5) with a positive charge made excellent labeling reagents for the detection of oligosaccharides by matrix-assisted laser desorption/ionization mass spectrometry. Cy3-labeled standard N-glycan could be detected at 200 amol on the MALDI target plate in reflectron mode without any purification procedures after the labeling reaction, which may meet the level of sensitivity required in proteome research. Despite the general recognition that the production of signals of oligosaccharides under MALDI conditions would be highly dependent on the matrix, most of the known N-glycans from chicken ovalbumin could be detected upon Cye derivatization nearly independent of the kind of matrix tested (e.g., nor-harman, 2,5-dihydroxybenzoic acid and alpha-cyano-4-hydroxycinnamic acid) without spoiling the signal strength. Postsource decay afforded simple spectra mainly consisting of Y-type fragment ions, thus simplifying the sequence analysis. In-source decay afforded a similar fragmentation pattern only when acidic matrixes were used. In addition, this derivatization technique was successfully applied to the profiling of N-glycans of gel-separated glycoproteins.  相似文献   
109.
Microwave dielectric measurements were performed in the frequency range from 1 mHz up to 30 GHz using a time domain reflectometry (TDR) method for emulsions and gels. Flat-end sample cells have been used in the TDR measurement to contact a small spot of the surface of those viscoelastic and solid samples without any destruction. Relaxation processes due to various water structures were observed for these aqueous systems. Relaxation parameters thus obtained offer information about these water structures and amounts. The relaxation strength obtained from the high frequency process due to free water can be an adequate measure of water content in spite of some ambiguities for different water structures in some materials. Comparisons of actual water contents in emulsion with those estimated from the relaxation strength indicate that water structure is affected by the interaction between water and micelle. Unfreezable water observed in DNA gel under the freezing point consists of bound water and a fraction of free water. Bound water molecules are still unfreezable to keep the double helical structure of DNA, when the fraction of free water is frozen at lower temperatures. These water structures determine physical properties of moist materials. TDR measuring technique with the flat-end cell is effective to investigate water structures in viscoelastic moist materials and to evaluate physical properties and structures of complex molecular systems.  相似文献   
110.
Cytomegalovirus (CMV) causes clinical issues primarily in immune-suppressed conditions. CMV-associated anterior uveitis (CMV-AU) is a notable new disease entity manifesting recurrent ocular inflammation in immunocompetent individuals. As patient demographics indicated contributions from genetic background and immunosenescence as possible underlying pathological mechanisms, we analyzed the immunogenetics of the cohort in conjunction with cell phenotypes to identify molecular signatures of CMV-AU. Among the immune cell types, natural killer (NK) cells are main responders against CMV. Therefore, we first characterized variants of polymorphic genes that encode differences in CMV-related human NK cell responses (Killer cell Immunoglobulin-like Receptors (KIR) and HLA class I) in 122 CMV-AU patients. The cases were then stratified according to their genetic features and NK cells were analyzed for human CMV-related markers (CD57, KLRG1, NKG2C) by flow cytometry. KIR3DL1 and HLA class I combinations encoding strong receptor–ligand interactions were present at substantially higher frequencies in CMV-AU. In these cases, NK cell profiling revealed expansion of the subset co-expressing CD57 and KLRG1, and together with KIR3DL1 and the CMV-recognizing NKG2C receptor. The findings imply that a mechanism of CMV-AU pathogenesis likely involves CMV-responding NK cells co-expressing CD57/KLRG1/NKG2C that develop on a genetic background of KIR3DL1/HLA-B allotypes encoding strong receptor–ligand interactions.  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