全文获取类型
收费全文 | 19437篇 |
免费 | 1124篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 273篇 |
综合类 | 75篇 |
化学工业 | 4228篇 |
金属工艺 | 526篇 |
机械仪表 | 415篇 |
建筑科学 | 1142篇 |
矿业工程 | 71篇 |
能源动力 | 413篇 |
轻工业 | 2427篇 |
水利工程 | 163篇 |
石油天然气 | 57篇 |
武器工业 | 1篇 |
无线电 | 1379篇 |
一般工业技术 | 4199篇 |
冶金工业 | 1819篇 |
原子能技术 | 146篇 |
自动化技术 | 3240篇 |
出版年
2023年 | 198篇 |
2022年 | 222篇 |
2021年 | 514篇 |
2020年 | 329篇 |
2019年 | 342篇 |
2018年 | 605篇 |
2017年 | 575篇 |
2016年 | 696篇 |
2015年 | 519篇 |
2014年 | 705篇 |
2013年 | 1283篇 |
2012年 | 975篇 |
2011年 | 1185篇 |
2010年 | 885篇 |
2009年 | 955篇 |
2008年 | 987篇 |
2007年 | 888篇 |
2006年 | 708篇 |
2005年 | 583篇 |
2004年 | 525篇 |
2003年 | 512篇 |
2002年 | 419篇 |
2001年 | 357篇 |
2000年 | 306篇 |
1999年 | 288篇 |
1998年 | 590篇 |
1997年 | 416篇 |
1996年 | 348篇 |
1995年 | 229篇 |
1994年 | 236篇 |
1993年 | 213篇 |
1992年 | 120篇 |
1991年 | 143篇 |
1990年 | 112篇 |
1989年 | 148篇 |
1988年 | 93篇 |
1987年 | 114篇 |
1986年 | 122篇 |
1985年 | 182篇 |
1984年 | 148篇 |
1983年 | 116篇 |
1982年 | 115篇 |
1981年 | 93篇 |
1980年 | 96篇 |
1979年 | 90篇 |
1978年 | 84篇 |
1977年 | 85篇 |
1976年 | 142篇 |
1975年 | 78篇 |
1973年 | 78篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Filip Sroubek Gabriel Cristóbal Jan Flusser 《IEEE transactions on image processing》2007,16(9):2322-2332
This paper presents a new approach to the blind deconvolution and superresolution problem of multiple degraded low-resolution frames of the original scene. We do not assume any prior information about the shape of degradation blurs. The proposed approach consists of building a regularized energy function and minimizing it with respect to the original image and blurs, where regularization is carried out in both the image and blur domains. The image regularization based on variational principles maintains stable performance under severe noise corruption. The blur regularization guarantees consistency of the solution by exploiting differences among the acquired low-resolution images. Several experiments on synthetic and real data illustrate the robustness and utilization of the proposed technique in real applications. 相似文献
82.
83.
84.
The authors used visual search tasks in which components of the classic flanker task (B. A. Eriksen & C. W. Eriksen, 1974) were introduced. In several experiments the authors obtained evidence of parallel search for a target among distractor elements. Therefore, 2-stage models of visual search predict no effect of the identity of those distractors. However, clear compatibility effects of the distractors were obtained: Responses were faster when the distractors were compatible with the response than when they were incompatible. These results show that even in parallel search tasks identity information is extracted from the distractors. In addition, alternative interpretations of the results in terms of the occasional identification of a distractor before or after the target was identified could be ruled out. The results showed that flat search slopes obtained in visual search experiments provide no benchmark for preattentive processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
85.
Jan Buijs 《Creativity & Innovation Management》2007,16(2):203-210
Innovating is a multi‐faceted process. In this paper, four different, yet intertwined aspects of this process are distinguished. The first aspect concerns the content of the innovation; a new product, a new technology or a new market. The second aspect concerns the group dynamics of the innovation team. The third aspect concerns seeing the innovation process as a creative process. And the fourth aspect has to do with leadership. Since these four aspects are simultaneously working together during the innovation process, the leaders of this process are working in a very difficult situation, as all four aspects need to be dealt with in different ways. Nearly all of them are, in one way or another, in conflict with one another. They may conflict in real actions, in time horizons (past, present or future) or in effect (positive reactions during market introduction do not garantee ultimate market success). This means that innovation leaders need to show a special kind of leadership. This leadership must be balanced, people‐focused and must include a high tolerance for ambiguity and paradoxes. They have to be nice and nasty at the same time. In short: innovation leaders should be some kind of controlled schizophrenics. 相似文献
86.
S. Klages M. Schöck C. Sürgers H. v. Löhneysen 《Journal of Low Temperature Physics》2004,137(3-4):509-522
The morphology and electronic transport of ultrathin Au films with thicknesses d = 1 ? 5 monolayers (ML) deposited on Si(111)7 × 7 surfaces is investigated by in situ scanning tunneling microscopy and electrical resistance measurements for temperatures T = 2 ? 300 K. With decreasing film thickness, i.e. decreasing sheet conductance Gs, a transition from a weakly conducting regime described by a logarithmic temperature dependence to an insulating regime occurs. In the insulating regime, the temperature dependence is described by Gs ∝ exp[?(T 0 /T) n] with an exponent n which gradually changes from 0.69 to 1 with decreasing film thickness. In contrast, for the Si(111)6 × 6-Au reconstruction obtained after annealing, an exponent n = 1/2 is found suggesting the formation of a soft Coulomb gap due to electron-electron interaction. PACS numbers: 68.37.-d, 68.55.-a, 73.50.-h, 73.25.+i, 81.15.-z 相似文献
87.
Jan‐Chan Huang 《应用聚合物科学杂志》2003,90(3):671-680
A modified method is discussed that is based on Farooque and Deshpande's method to obtain polymer–polymer interaction parameters using inverse gas chromatography (IGC) data. In the Farooque and Deshpande method, the ratio of the difference of probe–polymer interaction parameters between two polymers and the probe volume [(χ12 ? χ13)/V1] is used as the abscissa. In the modified method, the ratio [(?2χ12 + ?3χ13)/V1] is used as the abscissa. Experimental data previously reported for a poly(?‐caprolactone)‐polyepichlorohydrin (PCL/PECH) blend and a poly(ethyl acrylate)‐poly(vinyl propionate) (PEA/PVPr) blend are analyzed. It is found that the slopes obtained by the new method had smaller deviations from the theoretical values than the Farooque and Deshpande method. The standard deviations of both slopes and intercepts obtained from the new method are also smaller. Using the new method, the polymer–polymer interaction parameters obtained from the intercept are negative numbers for the PCL/PECH system and very small positive numbers for PEA/PVPr. Explanations are given for the probe and concentration dependency of the polymer–polymer interaction parameters that are generally observed in IGC studies. A new method for selecting the best probe for calculating the interaction parameter is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 671–680, 2003 相似文献
88.
Jan Lindblad 《电子设计技术》2004,11(10):58-64
即使在系统中事实上仍然有许多空闲内存时,内存碎片还会最终导致出现内存用完的情况.一个不断产生内存碎片的系统,不管产生的内存碎片多么小,只要时间足够长,就会将内存用完. 相似文献
89.
J. Riikonen A. Säynätjoki M. Sopanen H. Lipsanen J. Ahopelto 《Journal of Materials Science: Materials in Electronics》2003,14(5-7):403-405
The growth of GaAs on polycrystalline silicon-on-insulator (SOI) substrates by metal organic vapor phase epitaxy using a two-step growth process was studied in this work. We have compared the variation of the growth temperature and the thickness of the initial GaAs epilayer in the structures grown on polycrystalline SOI to ones grown on SOI and epi-Si. Structural properties were studied using high-resolution X-ray diffraction (XRD). The growth temperature had a strong effect on the FWHM of the (0 0 4) XRD curve in structures grown on SOI and epi-Si. In the case of polycrystalline SOI the effect was not as strong. Optical properties of the samples in which the optically active layer consisted of self-organized In0.5Ga0.5As quantum dots were investigated by photoluminescence measurements. The photoluminescence intensity from structures grown on polycrystalline SOI was comparable to that from structures grown on SOI and epi-Si. 相似文献
90.
Victor Chabanenko Roman Puźniak Adam Nabiałek Sergei Vasiliev Vladimir Rusakov Loh Huanqian Ritta Szymczak Henryk Szymczak Jan Jun Janusz Karpiński Vitaly Finkel 《Journal of Low Temperature Physics》2003,130(3-4):175-191
We present a study of magneto-thermal instabilities in polycrystalline MgB2 superconductor, by magnetic hysteresis loop measurements and by investigations of magnetic flux dynamics with a miniature Hall probe. Temperature and magnetic field ranges where the flux jumps may be observed have been determined. On the basis of measurements of the magnetic flux dynamics, an average magnetic diffusivity describing the process of the flux jump is estimated. This parameter is compared with the thermal and magnetic diffusivities calculated on the basis of available data for thermal conductivity, heat capacity and resistivity. It is shown that the estimated value of the field of the first flux jump is influenced significantly by the field dependence of specific heat. In order to explain the observed phenomenon, the temperature reached by the sample during the flux jump at different magnetic fields is calculated. 相似文献