全文获取类型
收费全文 | 3118篇 |
免费 | 51篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 111篇 |
综合类 | 6篇 |
化学工业 | 528篇 |
金属工艺 | 159篇 |
机械仪表 | 53篇 |
建筑科学 | 36篇 |
矿业工程 | 5篇 |
能源动力 | 72篇 |
轻工业 | 146篇 |
水利工程 | 15篇 |
石油天然气 | 1篇 |
无线电 | 410篇 |
一般工业技术 | 519篇 |
冶金工业 | 854篇 |
原子能技术 | 63篇 |
自动化技术 | 199篇 |
出版年
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 36篇 |
2020年 | 14篇 |
2019年 | 27篇 |
2018年 | 26篇 |
2017年 | 23篇 |
2016年 | 29篇 |
2015年 | 23篇 |
2014年 | 47篇 |
2013年 | 123篇 |
2012年 | 87篇 |
2011年 | 132篇 |
2010年 | 102篇 |
2009年 | 122篇 |
2008年 | 131篇 |
2007年 | 103篇 |
2006年 | 83篇 |
2005年 | 77篇 |
2004年 | 83篇 |
2003年 | 86篇 |
2002年 | 90篇 |
2001年 | 67篇 |
2000年 | 53篇 |
1999年 | 62篇 |
1998年 | 332篇 |
1997年 | 180篇 |
1996年 | 169篇 |
1995年 | 95篇 |
1994年 | 89篇 |
1993年 | 91篇 |
1992年 | 44篇 |
1991年 | 38篇 |
1990年 | 33篇 |
1989年 | 44篇 |
1988年 | 47篇 |
1987年 | 40篇 |
1986年 | 30篇 |
1985年 | 33篇 |
1984年 | 29篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 26篇 |
1980年 | 35篇 |
1979年 | 16篇 |
1978年 | 15篇 |
1977年 | 19篇 |
1976年 | 33篇 |
1975年 | 8篇 |
1973年 | 4篇 |
排序方式: 共有3177条查询结果,搜索用时 887 毫秒
31.
Verification of a diffuse pollution model involves comparing results actually observed with those predicted by precise model inputs. Acquisition of precise model inputs is, however, problematic. In particular, when the target catchment is large and substantial estimation uncertainty exists, not only model verification but also prediction is difficult. Therefore, in this study, rice-farming data were collected for all paddy fields from all farmers in a catchment and pesticide adsorption and degradation rates in paddy field soil samples were measured to obtain precise model inputs. The model inputs successfully verified the model's capability to predict pesticide concentrations in river water. Sensitivity analyses of the model inputs elucidated the processes significantly affecting pesticide runoff from rice farms. Pesticide adsorption and degradation rates of the soil did not significantly affect pesticide concentrations, although pesticide discharge to river water accounted for less than 50% of the total quantity of pesticide applied to fields, possibly owing to pesticide adsorption and degradation. The timing of increases in pesticide concentrations in river water was affected mostly by the farming schedule, including the time of pesticide application and irrigation, and secondarily by rainfall events. 相似文献
32.
The authors demonstrate that an injection locking technique suppresses the chirp in wavelength conversion using a laser diode. Waveform patterns of a 2.5 Gbit/s intensity-modulated signal after 128 km transmission through a normal dispersion singlemode fibre were improved by the injection locking technique 相似文献
33.
34.
Silicon nitride film deposited by LPCVD with newly developed in situ HF vapor cleaning has been studied and applied to fabricate dielectric films for stacked DRAM capacitors. Using this method, an oxide-free surface of underlaid poly-Si can be obtained. Silicon nitride film deposited on this surface has been verified by FTIR measurement to have the stoichiometrically proper composition of Si3N4 . However, the film was found to be selectively deposited on poly-Si electrodes. This selective deposition degrades the reliability of the stacked capacitor, because the silicon nitride can not completely cover the periphery of poly-Si electrodes on SiO2. We propose a simple process that avoids the problem making it possible to apply silicon nitride film to stacked-capacitor fabrication. Stacked capacitors fabricated by this process exhibit very low leakage current and high electrical reliability even for ultra-thin silicon nitride films less than 5 nm thick 相似文献
35.
36.
Hiroyuki Nishimura Fumio Inoue Akio Nakashiba Testuo Ishikawa 《Polymer Engineering and Science》1994,34(20):1529-1534
Fusion simulation is one of the key techniques in designing and producing electrofusion (EF) joints for gas distribution and in evaluating fusion joint integrity. This paper describes the result of a numerical simulation of a thermal fusion process, using the finite element method. A nonlinear heat transfer computer program was used to obtain the temperature profile of a large electrofusion joint at fusion. The effects of applied voltage, heating time, wire pitch, and ambient temperature were examined for designing a 150-mm EF joint. A method to shorten the cooling time was also investigated. The fusion condition range suitable for a 150-mm EF joint was found to be slightly narrower than that suitable for a 50-mm EF joint. Examination of the effect of wire pitch revealed that if the pitch is extremely large, thermal degradation starts in the resin close to the wire before the fusion-interface strength reaches the maximum value. We have developed a program to simulate the process of closing the gap between the pipe and the joint due to resin expansion and melting after the power is supplied. 相似文献
37.
38.
A Miyazawa H Inoue T Yoshioka T Horikoshi K Yanagisawa M Umeda K Inoue 《Canadian Metallurgical Quarterly》1992,59(4):1547-1554
Understanding the topographical relationships between phosphatidylserine (PS) and protein kinase C (PKC) within neurons can provide clues about the mechanism of translocation and activation of PKC. For this purpose we applied monoclonal antibodies (Abs) of PS and PKC to sections of developing rat cerebellum. The anti-PKC Ab immunohistochemical pattern showed homogeneous staining of Purkinje cells over various postnatal ages, whereas the anti-PS Ab staining showed a heterogeneous localization over these ages. Purkinje cells did not stain well between postnatal day 14 (PND 14) and PND 21, suggesting that the PS was lost from the membrane during preparation of the sections during this period. These data imply that interactions between PS and PKC vary in Purkinje cells during postnatal development. 相似文献
39.
Yamada T. Nakata Y. Hasegawa J. Amano N. Shibayama A. Sasago M. Matsuo N. Yabu T. Matsumoto S. Okada S. Inoue M. 《Solid-State Circuits, IEEE Journal of》1991,26(11):1506-1510
A 64-Mb dynamic RAM (DRAM) has been developed with a meshed power line (MPL) and a quasi-distributed sense-amplifier driver (qDSAD) scheme. It realizes high speed, t RAS=50 ns (typical) at V cc=3.3 V, and 16-b input/output (I/O). This MPL+qDSAD scheme can reduce sensing delay caused by the metal layer resistance. Furthermore, to suppress crosstalk noise, a V SS shield peripheral layout scheme has been introduced, which also widens power line widths. This 64-Mb DRAM was fabricated with 0.4-μm CMOS technology using KrF excimer laser lithography. A newly developed memory cell structure, the tunnel-shaped stacked-capacitor cell (TSSC), was adapted to this 64-Mb DRAM 相似文献
40.
T Ganbo K Hisamatsu H Inoue A Mizukoshi R Goto Y Murakami 《Canadian Metallurgical Quarterly》1995,33(4):199-202
The effects of leukotrienes C4 and D4 on ciliary activity of human paranasal sinus mucosa were investigated in vitro. Normal mucosa was surgically obtained from human paranasal sinuses and incubated in the form of tissue culture. Ciliated cells were magnified under an inverted microscope, and ciliary activity was photoelectrically measured. LTD4 progressively inhibited ciliary activity, and showed a more potent effect on ciliary activity compared to LTC4. The concentrations of LTC4 and LTD4 in the incubation medium were determined by radioimmunoassay when the mucosa was incubated with 10(-8) M LTC4. The concentration of LTD4 gradually increased and after 90 min reached the maximum of 0.71 x 10(-8) M, while that of LTC4 was reduced to about 10% of its initial concentration within 60 min. These results suggested the possible conversion of LTC4 to LTD4 on the mucosa, and that LTC4 can inhibit ciliary activity by means of LTD4. 相似文献