全文获取类型
收费全文 | 1479篇 |
免费 | 14篇 |
国内免费 | 180篇 |
专业分类
电工技术 | 53篇 |
综合类 | 13篇 |
化学工业 | 145篇 |
金属工艺 | 299篇 |
机械仪表 | 136篇 |
建筑科学 | 98篇 |
矿业工程 | 6篇 |
能源动力 | 34篇 |
轻工业 | 159篇 |
水利工程 | 5篇 |
石油天然气 | 103篇 |
无线电 | 190篇 |
一般工业技术 | 216篇 |
冶金工业 | 27篇 |
原子能技术 | 21篇 |
自动化技术 | 168篇 |
出版年
2017年 | 7篇 |
2013年 | 178篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 26篇 |
2009年 | 40篇 |
2008年 | 14篇 |
2006年 | 15篇 |
2005年 | 15篇 |
2004年 | 30篇 |
2003年 | 24篇 |
2002年 | 45篇 |
2001年 | 7篇 |
2000年 | 15篇 |
1999年 | 23篇 |
1998年 | 67篇 |
1997年 | 78篇 |
1996年 | 53篇 |
1995年 | 36篇 |
1994年 | 35篇 |
1993年 | 69篇 |
1992年 | 40篇 |
1991年 | 47篇 |
1990年 | 133篇 |
1989年 | 69篇 |
1988年 | 64篇 |
1987年 | 36篇 |
1986年 | 28篇 |
1985年 | 21篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 50篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1975年 | 29篇 |
1974年 | 34篇 |
1973年 | 22篇 |
1972年 | 22篇 |
1971年 | 14篇 |
1970年 | 28篇 |
1969年 | 12篇 |
1968年 | 18篇 |
1967年 | 9篇 |
1966年 | 12篇 |
1963年 | 11篇 |
1959年 | 7篇 |
1901年 | 6篇 |
排序方式: 共有1673条查询结果,搜索用时 0 毫秒
1.
C.A. Wedeking Research Assistant V.L. Snoeyink Professor R.A. Larson Professor J. Ding Research Assistant 《Water research》1987,21(8)
Surface oxygen has an important effect on the wet air regeneration (WAR) of powdered activated carbons (PAC) and on the adsorption properties of the regenerated PAC. Virgin and phenanthrene-loaded PACs were regenerated in a bench-scale reactor, and then analyzed to determine surface oxygen content, adsorption capacity, and extent of phenanthrene oxidation.Even though the virgin wood-base (WB) and lignite-base (LB) PACs had about the same oxygen content, the oxygen content of the WB PAC increased more than twice as much as the LB PAC during regeneration. The difference was caused by the larger amount of CO2-evolving oxides that formed on the WB PAC. WAR reduces the capacity of PAC for p-nitrophenol (PNP). Removing the surface oxides had varying effects on the carbon's capacity for PNP. Also, adsorbed phenanthrene was more easily oxidized on the WB PAC than on the LB PAC during regeneration. 相似文献
2.
E utrophication and severe oxygen depletion of the Danish seas have created a demand for nutrient removal from wastewater. Effluent concentrations from 2 to 0.3 mg/l P can be achieved by chemical precipitation. Nitrogen is best removed by combined nitrificationdenitrification. Effluent concentrations down to 3 to 4 mgll - can be achieved. There is technical and economical potential in combined biological P- and N-removal at marginal extra cost. Contact filtration has to be included to reach low concentrations of P. 相似文献
3.
4.
Professor Jorge Manuel Martins Margarida Lopes Almeida Professor Cristina Maria Coelho Dr João Ferra 《The Journal of Adhesion》2015,91(10-11):792-800
This paper presents a study on the curing conditions of several resin-impregnated papers and its impact on the performance of HPL (high-pressure decorative laminate). A new methodology for evaluating the bond strength development between the different layers of a HPL(overlay, decorative, and kraft papers) was developed using ABES (Automated Bonding Evaluation System) equipment. The proposed method can be applied to the study of the curing step of the different impregnated paper and the development of bonds between them (overlay paper on decorative paper, decorative paper on kraft paper, and kraft paper on kraft paper) trying to simulate the hot-pressing of an industrial HPL. This will permit to establish a more adapted temperature gradient in hot-press in order to achieve the same curing rate for all layers and provide a good final overall product quality. 相似文献
5.
Experimental‐numerical research on the seismic performance of URM buildings made of lightweight AAC blocks / Experimentell‐numerische Untersuchung zum seismischen Verhalten von unbewehrten Mauerwerksgebäuden aus Porenbetonblöcken 下载免费PDF全文
Assist. Prof. PhD Andra Penna Professor PhD Guido Magenes Maria Rota Researcher PhD Martina Mandirola MSc Annalisa Rosti MSc 《Mauerwerk》2015,19(2):130-143
Masonry walls constructed with lightweight AAC blocks and thin‐layer mortar meet the increasingly strict requirements of energy efficiency and sustainability. In this sense, they represent an excellent solution for modern buildings, not only for external cladding but also as loadbearing elements. Despite the possible advantages of using lightweight AAC masonry, a specific assessment of its seismic performance is mandatory in order to set design recommendations allowing to reach safety levels consistent with those required for other masonry types complying with EN 1998 standard requirements. A comprehensive study on the seismic performance of unreinforced masonry buildings made of lightweight AAC was carried out in an integrated experimental‐numerical approach. The experimental campaign provided the necessary information to setup a reliable numerical model to be extensively used to assess the seismic performance of a number of prototype AAC masonry buildings with different characteristics, by means of both linear and nonlinear static (pushover) analysis. The results of this systematic numerical assessment were eventually used to draft design recommendations, to set parameters (behaviour factors) to be used in linear analysis and to calibrate rules for simple buildings. 相似文献
6.
Dr Inayat B. Pathan Mr Santosh J. Munde Dr Santosh Shelke Professor Wahid Ambekar Dr C. Mallikarjuna Setty 《国际聚合物材料杂志》2019,68(4):165-174
The objective of the present investigation was to formulate curcumin loaded fish scale collagen (FSC)-hydroxypropyl methyl cellulose (HPMC K100) nanogel (CNG) for wound healing application. The curcumin nanoemulsion was prepared, characterized and loaded in FSC-HPMC nanogel. The nanogel was evaluated for ex-vivo permeation, in-vivo, skin irritation, and stability study. Ex-vivo permeation study demonstrated that CNG prolonged release and exhibited higher percent contraction value of wound compared to other formulations. In skin irritation study, formulation produced the score of less than 2 compared to control. It concluded that curcumin loaded FSC-HPMC nanogel could be prepared for wound healing applications. 相似文献
7.
Tropical Librarianship W. J. Plumbe The Scarecrow Press, Inc. Matuchen, N.J. and London, 1987 相似文献
8.
9.
10.
In recent years, the conservation of industrial heritage in China has gained increasing attention within the broader context of urban conservation practices. For both policy-makers and scholars, accommodating this industrial heritage will emerge as a pertinent issue for consideration as a growing number of industrial architectural legacies dating from the Republican and Maoist eras come under (re)development pressures. This paper thus traces the development of industrial heritage conservation practices in China and discusses several dilemmas intrinsic to this type of conservation, including issues of authenticity, representativeness, and distinction. Based on comparative case studies from China and other international precedents, this paper also seeks to illustrate the different approaches that could be pursued while still attaining a balance between competing interests and claims. 相似文献