全文获取类型
收费全文 | 1754篇 |
免费 | 103篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 25篇 |
综合类 | 14篇 |
化学工业 | 433篇 |
金属工艺 | 9篇 |
机械仪表 | 33篇 |
建筑科学 | 71篇 |
矿业工程 | 1篇 |
能源动力 | 43篇 |
轻工业 | 185篇 |
水利工程 | 25篇 |
石油天然气 | 1篇 |
无线电 | 154篇 |
一般工业技术 | 331篇 |
冶金工业 | 171篇 |
原子能技术 | 34篇 |
自动化技术 | 330篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 105篇 |
2021年 | 104篇 |
2020年 | 61篇 |
2019年 | 55篇 |
2018年 | 62篇 |
2017年 | 50篇 |
2016年 | 70篇 |
2015年 | 52篇 |
2014年 | 68篇 |
2013年 | 108篇 |
2012年 | 96篇 |
2011年 | 133篇 |
2010年 | 89篇 |
2009年 | 89篇 |
2008年 | 102篇 |
2007年 | 85篇 |
2006年 | 73篇 |
2005年 | 62篇 |
2004年 | 48篇 |
2003年 | 36篇 |
2002年 | 30篇 |
2001年 | 26篇 |
2000年 | 15篇 |
1999年 | 24篇 |
1998年 | 48篇 |
1997年 | 39篇 |
1996年 | 17篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有1860条查询结果,搜索用时 15 毫秒
1.
Fabiana Piscitelli Roberto Coccurello Antonio Totaro Alessandro Leuti Giacomo Giacovazzo Roberta Verde Emanuela Rossi Michele Podaliri Vulpiani Nicola Ferri Roberto Giacominelli Stuffler Vincenzo Di Marzo Sergio Oddi Tiziana Bisogno Mauro Maccarrone 《European Journal of Lipid Science and Technology》2019,121(10)
2.
3.
4.
The size effects on the mean values of the mechanical properties of condensed matter and on the related variances are analysed by means of a unified approach based on the multiscale character of energy dissipation. In particular, the scaling law for fragmentation energy density is obtained taking into account the self-similarity of fragments. It is based on a generalization of the three classical comminution laws that has been performed to evaluate the energy dissipation, computing volume and surface area of the particles for one- two- and three-dimensional fragmented objects. The result is general and can be applied to different fractal energy dissipation mechanisms, e.g., plasticity. Based on this approach, the scaling laws for mean and standard deviation values of the main mechanical properties of materials can be derived, like Young's and shear elastic moduli, ultimate normal and shear stresses and strains, fracture energy and toughness. 相似文献
5.
L Palazzo B Landi C Cellier G Roseau S Chaussade D Couturier J Barbier 《Canadian Metallurgical Quarterly》1997,29(9):850-853
BACKGROUND AND STUDY AIMS: Granular cell tumors of the esophagus are rare tumors. A definite diagnosis is achieved by endoscopic biopsies in only 50% of cases. Endoscopic ultrasonography (EUS) is the best procedure in the evaluation of upper gastrointestinal tract submucosal tumors. The aim of this study was to describe the endosonographic findings of esophageal granular cell tumors. METHODS: From January 1989 to March 1994, 15 patients with 21 granular cell tumors which had negative biopsies were examined by EUS (Olympus GF UM3 or GF UM20,7,5 and 12 MHz). In five cases, the tumor was also studied with a 20 MHz Olympus miniprobe. The final histological diagnoses were obtained by subsequent endoscopic snare resection in 20 cases and surgically in one case. RESULTS: The endosonographic features (with the GF UM3 or GF UM20) of esophageal granular cell tumors were: a) a tumor size of less than 2 cm in 95% of cases; b) an hypoechoic solid pattern in 100% of cases; c) a tumor arising in the inner layers in 95% (second echo-poor layer n=15; third echo-rich layer n=5). In one case, the endosonographic finding was transmural malignant infiltration of the esophageal wall (histologically confirmed). CONCLUSION: When a granular cell tumor of the esophagus is suspected, EUS can show the inner layer location of the tumor and thus contribute to planning the endoscopic resection or follow up. When the tumor also invades the outer layers, EUS can contribute to planning the surgical resection. 相似文献
6.
7.
Statistical machine translation systems are usually trained on large amounts of bilingual text (used to learn a translation
model), and also large amounts of monolingual text in the target language (used to train a language model). In this article
we explore the use of semi-supervised model adaptation methods for the effective use of monolingual data from the source language
in order to improve translation quality. We propose several algorithms with this aim, and present the strengths and weaknesses
of each one. We present detailed experimental evaluations on the French–English EuroParl data set and on data from the NIST
Chinese–English large-data track. We show a significant improvement in translation quality on both tasks. 相似文献
8.
The possibility of using the IEC flickermeter for the assessment of the limits of low frequency interharmonic voltages is critically analyzed. The response of flickermeters to interharmonic components is analytically investigated, obtaining approximation formulas for the calculation of Pst in the presence of couples of components at frequencies that are symmetric with reference to the fundamental and in the presence of one or more single components. The instrument characteristics and limitations are also highlighted, using the results obtained from a numerical implementation of the IEC flickermeter. Finally, the general problem of the limits of low frequency interharmonic voltages is discussed and practical solutions are proposed. 相似文献
9.
The interactivity effect in multimedia learning 总被引:4,自引:1,他引:3
10.
In comparing our calculated exciton energies with those obtained from pseudopotential calculations (Ref. 27) and from a previous
tight binding calculation (Ref. 30), we stated that the differences between the three semi-empirical calculations arise because
of different treatment of the nanocrystal surfaces. This appears not to be correct. Subsequent calculations with variable
Si-H parameters have shown that the band gap is actually rather insensitive to the actual value of these. Instead, the important
feature appears to be the overall quality of the bulk band structure parameterization. References 27 and 30 use more extensive
and higher quality empirical parameterizations for bulk Si than the sp3s∗ model used by us. Repeating our time dependent calculations with an improved sp3d5 parameterization results in similar values to those of Refs. 27 and 30 for the exciton energies.1 The agreement of the sp3s∗ values with experimental photoluminescence energies (Fig. 7) cannot, therefore, be regarded as well understood at this
time.1,2 相似文献