全文获取类型
收费全文 | 832篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 25篇 |
综合类 | 2篇 |
化学工业 | 140篇 |
金属工艺 | 20篇 |
机械仪表 | 15篇 |
建筑科学 | 6篇 |
能源动力 | 26篇 |
轻工业 | 36篇 |
水利工程 | 2篇 |
无线电 | 95篇 |
一般工业技术 | 125篇 |
冶金工业 | 270篇 |
原子能技术 | 39篇 |
自动化技术 | 44篇 |
出版年
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 8篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 17篇 |
2012年 | 18篇 |
2011年 | 32篇 |
2010年 | 27篇 |
2009年 | 35篇 |
2008年 | 30篇 |
2007年 | 22篇 |
2006年 | 13篇 |
2005年 | 19篇 |
2004年 | 12篇 |
2003年 | 22篇 |
2002年 | 20篇 |
2001年 | 21篇 |
2000年 | 18篇 |
1999年 | 21篇 |
1998年 | 91篇 |
1997年 | 55篇 |
1996年 | 41篇 |
1995年 | 40篇 |
1994年 | 30篇 |
1993年 | 24篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 16篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1973年 | 6篇 |
1969年 | 4篇 |
排序方式: 共有845条查询结果,搜索用时 15 毫秒
51.
Takeshi Kikuchi Makio Mogi Iichiro Okabe Kosuke Okada Hisashi Goto Yasuyuki Sasaki Takeki Fujimura Mitsuo Fukuda Akio Mitani 《International journal of molecular sciences》2015,16(10):24111-24126
Periodontal disease is caused by dental plaque biofilms, and the removal of these biofilms from the root surface of teeth plays a central part in its treatment. The conventional treatment for periodontal disease fails to remove periodontal infection in a subset of cases, such as those with complicated root morphology. Adjunctive antimicrobial photodynamic therapy (aPDT) has been proposed as an additional treatment for this infectious disease. Many periodontal pathogenic bacteria are susceptible to low-power lasers in the presence of dyes, such as methylene blue, toluidine blue O, malachite green, and indocyanine green. aPDT uses these light-activated photosensitizer that is incorporated selectively by bacteria and absorbs a low-power laser/light with an appropriate wavelength to induce singlet oxygen and free radicals, which are toxic to bacteria. While this technique has been evaluated by many clinical studies, some systematic reviews and meta-analyses have reported controversial results about the benefits of aPDT for periodontal treatment. In the light of these previous reports, the aim of this review is to provide comprehensive information about aPDT and help extend knowledge of advanced laser therapy. 相似文献
52.
[This corrects the article on p. 1930 in vol. 11, PMID: 20480050.]. 相似文献
53.
Haruyuki Makio Takashi Ochiai Hidetsugu Tanaka Terunori Fujita 《Advanced Synthesis \u0026amp; Catalysis》2010,352(10):1635-1640
A bis(phenoxyimine) group 4 transition metal catalyst (now known as FI catalysts) can discern ethylene from a mixture of ethylene and propylene at more than 99% selectivity. Denisty function theory (DFT) calculations revealed a spatially confined reaction site in the transition states of the migratory insertion which is just the right size for an ethylene molecule but too small for a propylene one. The substituents adjacent to the phenoxy‐oxygens are of crucial importance in developing the size/shape‐selectivity. 相似文献
54.
Marc Delcroix Keisuke Kinoshita Tomohiro Nakatani Shoko Araki Atsunori Ogawa Takaaki Hori Shinji Watanabe Masakiyo Fujimoto Takuya Yoshioka Takanobu Oba Yotaro Kubo Mehrez Souden Seong-Jun Hahm Atsushi Nakamura 《Computer Speech and Language》2013,27(3):851-873
Research on noise robust speech recognition has mainly focused on dealing with relatively stationary noise that may differ from the noise conditions in most living environments. In this paper, we introduce a recognition system that can recognize speech in the presence of multiple rapidly time-varying noise sources as found in a typical family living room. To deal with such severe noise conditions, our recognition system exploits all available information about speech and noise; that is spatial (directional), spectral and temporal information. This is realized with a model-based speech enhancement pre-processor, which consists of two complementary elements, a multi-channel speech–noise separation method that exploits spatial and spectral information, followed by a single channel enhancement algorithm that uses the long-term temporal characteristics of speech obtained from clean speech examples. Moreover, to compensate for any mismatch that may remain between the enhanced speech and the acoustic model, our system employs an adaptation technique that combines conventional maximum likelihood linear regression with the dynamic adaptive compensation of the variance of the Gaussians of the acoustic model. Our proposed system approaches human performance levels by greatly improving the audible quality of speech and substantially improving the keyword recognition accuracy. 相似文献
55.
Takayuki Goto Takao Watanabe Kyoichi Kinoshita Azusa Matsuda Masafumi Sera Tetsuo Fukase 《Journal of Low Temperature Physics》1996,105(3-4):401-406
Cu-NMR spectra and the nuclear spin-lattice relaxation rate T
1
-1
have been studied intensively on the bilayer type high-Tc cuprate La1.89Ca1.11Cu2O6+ (La2126). The resonance line shift showed a monotonic decrease with lowering temperature in the normal state, indicating that this compound belongs to the lightly-doped region. The Curie-Weiss temperature dependence of (T1T)–1 in the normal state shows that the pseudo spin-gap does not always exist in the light-doped bilayer systems. 相似文献
56.
57.
Self-organized rhodamine 6G particles prepared by wetting/dewetting process of an ethanol solution on a hydrophilic glass surface exhibits fluorescence without quenching, showing a sharp linewidth of 2nm with a large redshift, which indicates an existence of dye aggregates, similar to J-aggregates, inside the particle. Polarized evanescent field excitation showed that the dye molecule's transition moment along the pi-conjugation was oriented unidirectionally within particles and parallel to the substrate surface. This deduced dye orientation showed correlation between adjacent, but separated, particles and pointed roughly 45 degrees off the dewetting direction. In contrast, the particles of another pi-conjugated NK1420 dye, J-aggregates of which grows easily from an oversaturated solution, showed dye orientation along the dewetting direction preferably, still indicating the effect of self-organization, however based on a different mechanism. An annealing procedure revealed that both aggregates are in quasi-stable states, which is consistent with the rapidness of the dewetting process that may lead to crystallization in nonequilibrium. 相似文献
58.
利用超高压电镜与高能离子加速器连接装置 ,研究了氦 (He)对Fe Cr Ni和Fe Cr Mn两类奥氏体型合金辐照损伤行为的影响。观察了辐照过程中二次点缺陷的演变、空洞的形成以及辐照诱导晶界处溶质元素浓度的变化。实验结果表明 :He能促进两类合金空洞核心的增加 ,但空洞尺寸和密度不同 ;He能有效抑制辐照诱起晶界元素偏析 ,但对不同原子尺寸的溶质原子抑制效果不同。该差别是由于He的注入提高空位移动激活能和改变点缺陷与溶质原子相互作用的效果 相似文献
59.
The applicability of the band-stripping and complementary matching method has been demonstrated by the analysis of temperature-dependent near-infrared (NIR) absorption spectra in the 7500-6500 cm(-1) region of oleic acid (cis-9-octadecenoic acid) in the pure liquid state. This method is based on first derivative-second derivative pair (D1-D2) plots and a new concept called the complementary band, cBDi, created by subtracting all the rest of the bands, exclusive of the ith estimated band, eBDi, from an experimental spectrum. The degree of coincidence of both band shapes provides a suitable measure for the quality of fit for each individual component band. It has been confirmed from the present analysis of the NIR spectra of oleic acid measured over a temperature range of 16-79 degrees C that the change of the peak intensity of the component band at around 6915 cm(-1) due to the first overtone of an O-H stretching vibration of the monomer has two transition points around 35 and 55 degrees C. Moreover, the present study has provided new insight into the analysis of temperature-dependent spectral variations of oleic acid. Among the three temperature ranges, 16-35 degrees C, 35-55 degrees C, and 55-79 degrees C, in the first range the band near 6915 cm(-1) shows a slight increase and in the second range it has a linear intensity change with a slope of 0.002 a.u./degree C. In the third range, a rapid increase of the peak intensity is observed. This band exists even at 15 degrees C (just below the melting point) and shows a shift from 6910 to 6915 cm(-1) and a band narrowing from 85 to 80 cm(-1) (full width at half-height) over a temperature range of 16 to 79 degrees C. Furthermore, it has been found that there are two broad bands at around 6835 and 6778. 相似文献
60.
K Ikeda E Satoyoshi M Kinoshita N Wakata Y Iwasaki 《Canadian Metallurgical Quarterly》1998,37(9):784-787
Satoyoshi syndrome consists of painful intermittent muscle spasms, alopecia and diarrhea. The age of onset is commonly less than 20 years of age. Adult onset of this syndrome is rare. We report a 65-year-old Japanese woman with Satoyoshi's syndrome of adult onset. Satoyoshi's syndrome of adult onset shows no skeletal abnormalities, in comparison with the classical pediatric cases. The clinical features in our patient revealed the benign and long-term course of muscle spasm and alopecia. This progression differed markedly from the other patients of adult onset. Thus, the severity of Satoyoshi's syndrome is variable in adult onset cases, and this diagnosis should be considered in adults with various and unexplained muscle spasms. 相似文献