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   336篇
  免费   17篇
电工技术   9篇
化学工业   93篇
金属工艺   14篇
机械仪表   6篇
建筑科学   4篇
能源动力   5篇
轻工业   57篇
水利工程   3篇
无线电   23篇
一般工业技术   73篇
冶金工业   44篇
自动化技术   22篇
  2023年   2篇
  2022年   8篇
  2021年   20篇
  2020年   11篇
  2019年   9篇
  2018年   4篇
  2017年   12篇
  2016年   5篇
  2015年   9篇
  2014年   10篇
  2013年   20篇
  2012年   16篇
  2011年   11篇
  2010年   6篇
  2009年   15篇
  2008年   18篇
  2007年   9篇
  2006年   14篇
  2005年   9篇
  2004年   9篇
  2003年   8篇
  2002年   14篇
  2001年   2篇
  2000年   5篇
  1999年   3篇
  1998年   16篇
  1997年   10篇
  1996年   11篇
  1995年   4篇
  1994年   9篇
  1993年   10篇
  1992年   6篇
  1991年   3篇
  1990年   4篇
  1989年   3篇
  1988年   2篇
  1987年   5篇
  1986年   4篇
  1985年   2篇
  1984年   3篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
  1976年   6篇
  1964年   1篇
排序方式: 共有353条查询结果,搜索用时 218 毫秒
1.
Intraneural injection of 10-20 x 10(6) viable Mycobacterium leprae into the sciatic nerve of normal, unsensitized, Swiss white mice gives rise to a tuberculoid type of granulomatous response in 2 weeks. The same dose of viable M. leprae when injected into the sciatic nerves of unsensitized immunosuppressed mice (T200 x 5R) elicited a macrophage response. When macrophages were systemically immobilized using an intraperitoneal injection of silica quartz dust in normal mice, the lesion produced was of the lepromatous type, suggesting a role for the macrophage in the induction of the tuberculoid type of granulomatous response. In all of these in situ experiments, M. leprae failed to enter the Schwann cells.  相似文献   
2.
3.
4.
Chemiluminescence (CL) of the systems containing Eu2+ or HCO3 ions and hydrogen peroxide was studied. The kinetic curves and CL emission spectra of the systems were discussed. The emission spectrum of the system containing carbonates revealed two emission maxima: the first directly after initiation of the reaction by hydrogen peroxide and the second in several seconds after the first. On the basis of the characteristic bands in the CL spectrum the emitters in the system Eu2+/HCO3/H2O2 were identified as: excited Eu3+ ions and excited products of carbonate decomposition. The emission bands for λ=600 and 420 nm appeared in a time distance of a few ten seconds.  相似文献   
5.
Summary By reacting esterification of phenolphtalein with methacrylate chloride, phenolphtalein dimethacrylate was obtained. Based on the results of elemental analysis, FTIR, 1H-NMR and 13C-NMR spectra, the structure of the product was proposed. The dimethacrylate was used as new crosslinker to crosslink poly(methyl methacrylate) (PMMA). The influence of the amount dimethacrylate on the crosslink density and some properties of the crosslinked polymers networks such as swelling, mechanical properties (tensile strength and elongation at break) and thermal stability were examined.  相似文献   
6.
The one-step metal promoted reaction between salicylaldehyde and 4-methyl-1,3-phenylenediamine in the presence of lanthanum(III) or gadolinium(III) nitrate yields new salicylaldimine complexes containing N,N′-bis(salicylidene)-4-methyl-1,3-phenylenediamine as a result of the [2 + 1] Schiff base condensation. The crystal structure of the gadolinium complex reveals a dinuclear species with four unionized ligands coordinating in the monodentate and bridging bidentate fashion, using exclusively the oxygens as donor atoms with the nitrogen atoms not being involved in coordination. The coordination number of nine is achieved by involving three bidentate nitrate counterions in the coordination sphere.  相似文献   
7.
The paper provides comparison of three different approaches to on-line tuning of generalized adaptive notch filters (GANFs) — the algorithms used for identification/tracking of quasi-periodically varying dynamic systems. Tuning is needed to adjust adaptation gains, which control tracking performance of GANF algorithms, to the unknown and/or time time-varying rate of system nonstationarity. Two out of three compared approaches are classical solutions — the first one incorporates sequential optimization of adaptation gains while the second one is based on the concept of parallel estimation. The main contribution of the paper is that it suggests the third way — it shows that the best results can be achieved when both approaches mentioned above are combined in a judicious way. Such joint sequential/parallel optimization preserves advantages of both treatments: adaptiveness (sequential approach) and robustness to abrupt changes (parallel approach). Additionally the paper shows how, using the concept of surrogate outputs, one can extend the proposed single-frequency algorithm to the multiple frequencies case, without falling into the complexity trap known as the “curse of dimensionality”.  相似文献   
8.
Developing a satisfactory and effective method for auto-annotating images that works under general conditions is a challenging task. The advantages of such a system would be manifold: it can be used to annotate existing, large databases of images, rendering them accessible to text search engines; or it can be used as core for image retrieval based on a query image’s visual content. Manual annotation of images is a difficult, tedious and time consuming task. Furthermore, manual annotations tend to show great inter-person variance: considering an image, the opinions about what elements are significant and deserve an annotation vary strongly. The latter poses a problem for the evaluation of an automatic method, as an annotation’s correctness is greatly subjective. In this paper we present an automatic method for annotating images, which addresses one of the existing methods’ major limitation, namely a fixed annotation length. The proposed method, PATSI, automatically chooses the resulting annotation’s length for each query image. It is held as simple as possible and a build-in parameter optimization procedure renders PATSI de-facto parameter free. Finally, PATSI is evaluated on standard datasets, outperforming various state-of-the-art methods.  相似文献   
9.
10.
Methods of electron microscopy and X-ray diffraction have been used to investigate structural and phase transformations in the aluminum alloy of grade A2024 (Al–4.5 Cu–1.37 Mg–0.61 Mn–0.07 Si–0.27 Fe–0.02 Zn–0.02 Ti (wt %)) after aging and deformation by shear under high quasi-static pressure. It has been shown that the combination of two-stage aging with megaplastic deformation leads to the refinement of the structure to a nanolevel and to strengthening of the alloy (to an increase in the microhardness to 3000 MPa). The values of true deformation at which the deformation-induced dissolution of the particles of the strengthening S phase occurs have been determined.  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