全文获取类型
收费全文 | 944篇 |
免费 | 97篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 259篇 |
金属工艺 | 18篇 |
机械仪表 | 21篇 |
建筑科学 | 24篇 |
矿业工程 | 1篇 |
能源动力 | 15篇 |
轻工业 | 194篇 |
水利工程 | 13篇 |
石油天然气 | 7篇 |
无线电 | 40篇 |
一般工业技术 | 120篇 |
冶金工业 | 132篇 |
原子能技术 | 3篇 |
自动化技术 | 189篇 |
出版年
2024年 | 3篇 |
2023年 | 7篇 |
2022年 | 24篇 |
2021年 | 35篇 |
2020年 | 19篇 |
2019年 | 27篇 |
2018年 | 37篇 |
2017年 | 29篇 |
2016年 | 46篇 |
2015年 | 32篇 |
2014年 | 41篇 |
2013年 | 61篇 |
2012年 | 56篇 |
2011年 | 60篇 |
2010年 | 48篇 |
2009年 | 52篇 |
2008年 | 37篇 |
2007年 | 44篇 |
2006年 | 40篇 |
2005年 | 33篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 24篇 |
2001年 | 16篇 |
2000年 | 25篇 |
1999年 | 16篇 |
1998年 | 57篇 |
1997年 | 34篇 |
1996年 | 25篇 |
1995年 | 17篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1963年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有1045条查询结果,搜索用时 15 毫秒
1.
Atmospheric corrosion of reference metals in Antarctic sites 总被引:1,自引:0,他引:1
Manuel Morcillo Beln Chico Daniel de la Fuente Elisabete Almeida Günter Joseph Susana Rivero Blanca Rosales 《Cold Regions Science and Technology》2004,40(3):165-178
This paper presents the results obtained at three Antarctic test sites participating in the “Ibero-American Map of Atmospheric Corrosiveness” (MICAT), a project on atmospheric corrosion carried out during the period 1988–1994 at some 70 sites distributed across 12 countries of the Latin-American region, Spain and Portugal. The three Antarctic sites are located near the coastline.The singular climatic characteristics of Antarctic regions are related with the purity of the air, the absence of rainfall and the formation of ice on the metallic surface during an important part of the exposure time. However, electrochemical activity is possible below ice layers. This situation affects the structure and morphology of corrosion product films and the resulting corrosion rates of metallic surfaces. 相似文献
2.
3.
Hepatobiliary cystadenoma is a rare hepatic lesion characterized by a multiloculated cyst lined by cuboidal or columnar epithelial cells. Four cases of hepatobiliary cystadenoma with mesenchymal stroma (HCMS) and one case of hepatobiliary cystadenoma with intracystic epithelial component were studied by light microscopy, immunohistochemical methods, and electron microscopy. Similar studies were conducted on six fetal gallbladder tissues, representing the biliary tree, and two adult ovarian tissues. By light microscopy, the columnar epithelium of the five cases of hepatobiliary cystadenoma was similar to the epithelium of the developing gallbladder. The spindle cell stroma of the HCMS and the subepithelial spindle cells of the developing gallbladders showed similar reactivity to smooth-muscle actin. Vimentin reactivity was strongly positive in the stroma of the HCMS, and in the fetal gallbladders it was only noted in the subepithelial spindle cells of the 15-week gestation fetal gallbladder tissues. By electron microscopy, the epithelium lining the hepatic lesions showed characteristic gastrointestinal features and was identical to the epithelia lining the embryonic gallbladders. Furthermore, the mesenchymal stroma of the HCMS recapitulated the features found in subepithelial tissues in developing gallbladders. Although the ovarian stroma resembled the stroma of the HCMS by light microscopy, the immunohistochemical reactions and the electron microscopic studies showed dissimilarities. This study supports the hypothesis that the hepatobiliary cystadenomas arise from ectopic embryonic tissues destined to form the adult gallbladder. 相似文献
4.
A patient who developed a mixed neuroendocrine carcinoma and adenocarcinoma at the site of a previous long-standing ileostomy is reported. The neuroendocrine features are documented by both ultrastructural and immunocytochemical findings. Carcinoma arising in an ileostomy site is rare but has been recorded in patients with long-standing ileostomies after colectomy for chronic inflammatory bowel disease, as in this patient. Neuroendocrine carcinoma developing in this setting apparently has not been described before, however. 相似文献
5.
6.
Nonlinear distortion generated by DSF-based optical-phase conjugators in analog optical systems 总被引:1,自引:0,他引:1
In this paper, the nonlinear distortion induced by dispersion-shifted-fiber-based optical-phase conjugators (OPCs) in intensity-modulated subcarrier multiplexing optical systems is evaluated. In this study, it is shown that the nonlinear distortion mainly arises from the four-wave mixing (FWM) process during the phase conjugation, although there also exists influences from other nonlinear effects. Closed expressions for calculating the second- and third-order harmonic distortions due to FWM, self-phase modulation, cross-phase modulation and group-velocity dispersion effects in the dispersion-shifted-fiber-based OPC are also reported for the first time. The influence of several system design parameters, such as the optical modulation index, the number of channels, the input optical powers, and the effective area of the dispersion-shifted fiber on the compensation of fiber-induced nonlinear distortions employing the optical-phase conjugation technique, is considered. 相似文献
7.
A.B. Bourlinos S. RayChowdhury R. Herrera D.D. Jiang Q. Zhang L.A. Archer E.P. Giannelis 《Advanced functional materials》2005,15(8):1285-1290
Recently, we have developed a novel family of functionalized nanostructures that exhibit liquid‐like behavior in the absence of solvents and preserve their nanostructure in the liquid state. The gallery of nanostructures developed so far includes functionalized silica and magnetic iron oxide nanoparticles, layer‐like organosilicate nanoparticles, polyoxometalate clusters, and organic–inorganic hybrid networks. In an effort to demonstrate the wider applicability of this concept and to provide a deeper insight into this class of materials, the present work cites additional paradigms of functionalized nanostructures with similar behavior as above. In one case, surface functionalization of anatase nanoparticles (TiO2, an inorganic nanostructure) with a quaternary ammonium organosilane leads to ionically modified nanoparticles that, when electrostatically combined with a poly(ethylene glycol) (PEG)‐tailed sulfonate anion, exhibit liquid‐like behavior in the absence of solvents. In a different but quite interesting case of a bionanostructure, ion‐exchange functionalization of a DNA oligonucleotide with a PEG‐tailed quaternary ammonium cation leads to an easily separable liquid derivative with attractive features. These examples show the versatility of this concept over a range of nanostructures. 相似文献
8.
9.
Some structural results about the interactor of a given right invertible system are presented. An original form for this operator, which directly exhibits structural information such as infinite-zero structure or essential orders, is provided. Moreover, this form allows the linkage of the infinite and essential structures of a system 相似文献
10.
K Sakaguchi JE Herrera S Saito T Miki M Bustin A Vassilev CW Anderson E Appella 《Canadian Metallurgical Quarterly》1998,12(18):2831-2841