全文获取类型
收费全文 | 5257篇 |
免费 | 97篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 277篇 |
综合类 | 10篇 |
化学工业 | 924篇 |
金属工艺 | 121篇 |
机械仪表 | 103篇 |
建筑科学 | 77篇 |
能源动力 | 137篇 |
轻工业 | 370篇 |
水利工程 | 17篇 |
石油天然气 | 2篇 |
无线电 | 582篇 |
一般工业技术 | 830篇 |
冶金工业 | 1478篇 |
原子能技术 | 141篇 |
自动化技术 | 293篇 |
出版年
2023年 | 23篇 |
2022年 | 53篇 |
2021年 | 75篇 |
2020年 | 28篇 |
2019年 | 55篇 |
2018年 | 54篇 |
2017年 | 34篇 |
2016年 | 61篇 |
2015年 | 61篇 |
2014年 | 77篇 |
2013年 | 172篇 |
2012年 | 153篇 |
2011年 | 199篇 |
2010年 | 165篇 |
2009年 | 162篇 |
2008年 | 178篇 |
2007年 | 161篇 |
2006年 | 161篇 |
2005年 | 123篇 |
2004年 | 125篇 |
2003年 | 147篇 |
2002年 | 105篇 |
2001年 | 125篇 |
2000年 | 101篇 |
1999年 | 161篇 |
1998年 | 576篇 |
1997年 | 390篇 |
1996年 | 270篇 |
1995年 | 159篇 |
1994年 | 146篇 |
1993年 | 148篇 |
1992年 | 80篇 |
1991年 | 67篇 |
1990年 | 67篇 |
1989年 | 65篇 |
1988年 | 62篇 |
1987年 | 38篇 |
1986年 | 53篇 |
1985年 | 45篇 |
1984年 | 52篇 |
1983年 | 39篇 |
1982年 | 44篇 |
1981年 | 36篇 |
1980年 | 40篇 |
1979年 | 29篇 |
1978年 | 23篇 |
1977年 | 34篇 |
1976年 | 47篇 |
1975年 | 16篇 |
1973年 | 22篇 |
排序方式: 共有5362条查询结果,搜索用时 0 毫秒
111.
S Lindstrom A Endo S Sugita M Pecoraro Y Hiromoto M Kamada T Takahashi K Nerome 《Canadian Metallurgical Quarterly》1998,143(8):1585-1598
Matrix (M) and nonstructural (NS) genes of thirteen equine H3N8 and H7N7 influenza viruses were sequenced and analyzed from an evolutionary point of view. The M and NS genes of H3N8 viruses isolated between 1989 and 1993 evolved into two minor branch clusters, including isolates from Europe and the American continent, respectively. It was noteworthy to reveal that the nucleotide sequences of the M and NS genes of an earlier American strain showed highest homology to those of recent European viruses. "Frozen evolution" was observed in the M and NS genes of A/eq/LaPlata/1/88. It was also evident that the NS gene of an H7N7 virus from 1977 was very similar to that of a 1979-H3N8 virus, while the M gene was closest phylogenetically to that of the earliest H7N7 virus isolated in 1956. Furthermore, the M2 protein of A/eq/Newmarket/1/77 virus contained a carboxyl terminal deletion of three amino acids. The evolutionary rates of the M and NS genes of H3N8 equine influenza viruses were estimated to be 5.4 x 10(-4) and 5.1 x 10(-4) substitutions per site per year, respectively, which were slower than those of human viruses. 相似文献
112.
113.
Oda T. Kato T. Takahashi T. Shimizu K. 《Industry Applications, IEEE Transactions on》1998,34(2):268-272
Catalyst (copper-coated zeolite catalyst, i.e., Cu-ZSM-5) was used to enhance NOx removal plasma chemical reactions. Two kinds of hydrocarbons (2-propane-1-ol, 2-propanol) were added to the synthesized flue gas before the nonthermal plasma process, and their effects on NOx removal characteristics were investigated. Enhancement effects of NOx removal by the nonthermal plasma process with hydrocarbons as the additives were confirmed. Usually, the catalyst's working temperature is much higher than the room temperature. A catalytic reactor was installed after the plasma reactor. Catalytic effects on NOx removal characteristics disappeared when the synthesized flue gas temperature was increased (~250°C). When the synthesized flue gas temperature was at room temperature, about 90% NO x removal efficiency was realized with a combination of hydrocarbons, the catalytic reactor, and the pulsed discharge plasma 相似文献
114.
Hiroyuki Ishida Author Vitae Tomokazu Takahashi Author Vitae Author Vitae Hiroshi Murase Author Vitae 《Pattern recognition》2010,43(8):2799-2806
We propose a novel sequence alignment algorithm for recognizing handwriting gestures by a camera. In the proposed method, an input image sequence is aligned to the reference sequences by phase-synchronization of analytic signals which are transformed from original feature values. A cumulative distance is calculated simultaneously with the alignment process, and then used for the classification. A major benefit of this method is that over-fitting to sequences of incorrect categories is restricted. The proposed method exhibited higher recognition accuracy in handwriting gesture recognition, compared with the conventional dynamic time warping method which explores optimal alignment results for all categories. 相似文献
115.
This paper introduces a method for automatically generating continuous line illustrations, drawings consisting of a single line, from a given input image. Our approach begins by inferring a graph from a set of edges extracted from the image in question and obtaining a path that traverses through all edges of the said graph. The resulting path is then subjected to a series of post‐processing operations to transform it into a continuous line drawing. Moreover, our approach allows us to manipulate the amount of detail portrayed in our line illustrations, which is particularly useful for simplifying the overall illustration while still retaining its most significant features. We also present several experimental results to demonstrate that our approach can automatically synthesize continuous line illustrations comparable to those of some contemporary artists. 相似文献
116.
We propose a recognition method of character-string images captured by portable digital cameras. A challenging task in character-string
recognition is the segmentation of characters. In the proposed method, a hypothesis graph is used for recognition-based segmentation
of the character-string images. The hypothesis graph is constructed by the subspace method, using eigenvectors as conditionally
elastic templates. To obtain these templates, a generation-based approach is introduced in the training stage. Various templates
are generated to cope with low-resolution. We have experimentally proved that the proposed scheme achieves high recognition
performance even for low-resolution character-string images.
The text was submitted by the authors in English.
Hiroyuki Ishida. Received his B.S. and M.S. degrees from the Department of Information Engineering and from the Graduate School of Information
Science, respectively, at Nagoya University. He is currently pursuing a Ph.D. in Information Science at Nagoya University.
Ichiro Ide. Received his B.S. degree from the Department of Electronic Engineering, his M.S. degree from the Department of Information
Engineering, and his Ph.D. from the Department of Electrical Engineering at the University of Tokyo. He is currently an Associate
Professor in the Graduate School of Information Science at Nagoya University.
Tomokazu Takahashi. Received his B.S. degree from the Department of Information Engineering at Ibaraki University, and his M.S. and Ph.D. from
the Graduate School of Science and Engineering at Ibaraki University. His research interests include computer graphics and
image recognition.
Hiroshi Murase. Received his B.S., M.S., and Ph.D. degrees from the Graduate School of Electrical Engineering at Nagoya University. He is
currently a Professor in the Graduate School of Information Science at Nagoya University. He received the Ministry Award from
the Ministry of Education, Culture, Sports, Science and Technology in Japan in 2003. He is a Fellow of the IEEE. 相似文献
117.
Yamamoto T Kato R Yamamoto HM Fukaya A Yamasawa K Takahashi I Akutsu H Akutsu-Sato A Day P 《The Review of scientific instruments》2007,78(8):083906
We have developed a technique for the anisotropic extension of fragile molecular crystals. The pressure medium and the instrument, which extends the pressure medium, are both made from epoxy resin. Since the thermal contraction of our instrument is identical to that of the pressure medium, the strain applied to the pressure medium has no temperature dependence down to 2 K. Therefore, the degree of extension applied to the single crystal at low temperatures is uniquely determined from the degree of extension in the pressure medium and thermal contractions of the epoxy resin and the single crystal at ambient pressure. Using this novel instrument, we have measured the temperature dependence of the electrical resistance of metallic, superconducting, and insulating materials. The experimental results are discussed from the viewpoint of the extension (compression) of the lattice constants along the parallel (perpendicular) direction. 相似文献
118.
Kanamaru Y Gota H Fujimoto K Ikeyama T Asai T Takahashi T Nogi Y 《The Review of scientific instruments》2007,78(3):036105
A magnetic probe array is constructed to measure precisely the spatial structure of a small fluctuating field included in a strong confinement field that varies with time. To exclude the effect of the confinement field, the magnetic probes consisting of figure-eight-wound coils are prepared. The spatial structure of the fluctuating field is obtained from a Fourier analysis of the probe signal. It is found that the probe array is more sensitive to the fluctuating field with a high mode number than that with a low mode number. An experimental demonstration of the present method is attempted using a field-reversed configuration plasma, where the fluctuating field with 0.1% of the confinement field is successfully detected. 相似文献
119.
Jun Xin Jianjun Li Anthony Vetro Shun-ichi Sekiguchi 《Multimedia Tools and Applications》2007,35(2):203-223
This paper describes novel transcoding techniques aimed for low-complexity MPEG-2 to H.264/AVC transcoding. An important application
for this type of conversion is efficient storage of broadcast video in consumer devices. The architecture for such a system
is presented, which includes novel motion mapping and mode decision algorithms. For the motion mapping, two algorithms are
presented. Both efficiently map incoming MPEG-2 motion vectors to outgoing H.264/AVC motion vectors regardless of the block
sizes that the motion vectors correspond to. In addition, the algorithm maps motion vectors to different reference pictures,
which is useful for picture type conversion and prediction from multiple reference pictures. We also propose an efficient
rate-distortion optimised macroblock coding mode decision algorithm, which first evaluates candidate modes based on a simple
cost function so that a reduced set of candidate modes is formed, then based on this reduced set, we evaluate the more complex
Lagrangian cost calculation to determine the coding mode. Extensive simulation results show that our proposed transcoder incorporating
the proposed algorithms achieves very good rate-distortion performance with low complexity. Compared with the cascaded decoder-encoder
solution, the coding efficiency is maintained while the complexity is significantly reduced.
相似文献
Shun-ichi SekiguchiEmail: |
120.
N. Umesaki M. Takahashi M. Tatsumisago T. Minami 《Journal of Materials Science》1993,28(13):3473-3481
Raman spectra of glasses in the Li2O-SiO2 system (41.3 Li2O 61.3 mol%), prepared by rapid quenching, were measured. The proportions of SiO4 units with 1–4 non-bridging oxygens per silicon (NBO/Si) and the fractions of bridging oxygen, non-bridging oxygen and free or full-active oxygen were determined for these glasses from quantitative analysis of the Raman spectra obtained. X-ray structural analysis of Li2O-SiO2 showed an increasing elongation of the average atomic distance of the Si-O pair with increase in Li2O content due to weakening of the Si-O bond. 相似文献