全文获取类型
收费全文 | 1827篇 |
免费 | 53篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 13篇 |
综合类 | 3篇 |
化学工业 | 279篇 |
金属工艺 | 66篇 |
机械仪表 | 43篇 |
建筑科学 | 26篇 |
矿业工程 | 2篇 |
能源动力 | 87篇 |
轻工业 | 73篇 |
水利工程 | 8篇 |
石油天然气 | 5篇 |
无线电 | 102篇 |
一般工业技术 | 314篇 |
冶金工业 | 740篇 |
原子能技术 | 6篇 |
自动化技术 | 127篇 |
出版年
2024年 | 4篇 |
2023年 | 31篇 |
2022年 | 48篇 |
2021年 | 57篇 |
2020年 | 58篇 |
2019年 | 48篇 |
2018年 | 69篇 |
2017年 | 67篇 |
2016年 | 68篇 |
2015年 | 33篇 |
2014年 | 58篇 |
2013年 | 104篇 |
2012年 | 45篇 |
2011年 | 78篇 |
2010年 | 57篇 |
2009年 | 51篇 |
2008年 | 47篇 |
2007年 | 47篇 |
2006年 | 26篇 |
2005年 | 24篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 13篇 |
2001年 | 17篇 |
2000年 | 14篇 |
1999年 | 32篇 |
1998年 | 206篇 |
1997年 | 117篇 |
1996年 | 72篇 |
1995年 | 43篇 |
1994年 | 32篇 |
1993年 | 41篇 |
1992年 | 14篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 21篇 |
1986年 | 19篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 27篇 |
1976年 | 55篇 |
1970年 | 2篇 |
排序方式: 共有1894条查询结果,搜索用时 15 毫秒
1.
We considered the magnetohydrodynamic (MHD) free convective flow of an incompressible electrically conducting viscous fluid past an infinite vertical permeable porous plate with a uniform transverse magnetic field, heat source and chemical reaction in a rotating frame taking Hall current effects into account. The momentum equations for the fluid flow during absorbent medium are controlled by the Brinkman model. Through the undisturbed state, both the plate and fluid are in a rigid body rotation by the uniform angular velocity perpendicular to an infinite vertical plate. The perpendicular surface is subject to the homogeneous invariable suction at a right angle to it and the heat on the surface varies about a non-zero unvarying average whereas the warmth of complimentary flow is invariable. The systematic solutions of the velocity, temperature, and concentration distributions are acquired systematically by utilizing the perturbation method. The velocity expressions consist of steady-state and fluctuating situations. It is revealed that the steady part of the velocity field has a three-layer characteristic while the oscillatory part of the fluid field exhibits a multi-layer characteristic. The influence of various governing flow parameters on the velocity, temperature, and concentration are analyzed graphically. We also discuss computational results for the skin friction, Nusselt number, and Sherwood number in the tabular forms. 相似文献
2.
3.
Jagadeesh Babu Sriramoju Murthy Muniyappa Navya Rani Marilingaiah Chetana Sabbanahalli Manjunath Shetty Ravi Mudike Chitrabanu C.P Prasanna D. Shivaramu Nagaraju G Kanchugarakoppal S. Rangappa Ananda Kumar C.S Dinesh Rangappa 《Ceramics International》2021,47(7):10314-10321
Application of brown titanium dioxide (TiO2-x) and its modified composite forms in the photocatalytic decomposition of organic pollutants in the environment is a promising way to provide solutions for environmental redemption. Herein, we report the synthesis of effective and stable TiO2-x nanoparticles with g-C3N4, RGO, and multiwalled carbon nanotubes (CNTs) using a simple hydrothermal method. Among all the as-synthesized samples, excellent photocatalytic degradation activity was observed for RGO-TiO2-x nanocomposite with high rate constants of 0.075 min?1, 0.083 min?1 and 0.093 min?1 for methylene blue, rhodamine-B, and rosebengal dyes under UV–Visible light irradiation, respectively. The altered bandgap (1.8 eV) and the large surface area of RGO-TiO2-x nanocomposite impacts on both absorption of visible light and efficiency of photogenerated charge electron (e?)/hole (h+) pair separation. This resulted in enhanced photocatalytic property of carbon-based TiO2-x nanocomposites. A systematic study on the influence of different carbon nanostructures on the photocatalytic activity of brown TiO2-x is carried out. 相似文献
4.
NP Kirilenko 《Canadian Metallurgical Quarterly》1993,38(9):13-15
Levels of temporary invalidity because of catching cold were analyzed in 101 working women over two years and these women's levels of serum iron, total iron-binding capacity of the serum, transferrin saturation with iron, serum ferritin, and red cell ferritin measured. Women with stable iron reserves in the body virtually have no sick leaves because of catching cold, whereas in those with iron deficiency susceptibility to catching cold is increased, and if iron metabolism intensity in the body grows, invalidity periods are much longer. Normalization of not only iron reserves in the body, but correction of iron metabolism as well should be regarded as a factor exerting a favorable effect on body resistance to catching cold. 相似文献
5.
6.
7.
The development of the semi-theoretical correlation in Hadzisdmajlovic et al. (1983) for predicting the maximum spoutable height in a spout-fluid bed, is observed to involve certain discrepancies. Based on their experimental data, a new correlation is proposed. 相似文献
8.
The partial substitution of Ga at the Cu(1) (chain) sites of the YBa2Cu3O7 structure allows synthesis at ambient pressure of Ba-free analogs, e.g., YSr2Cu2.7Ga0.3O7?δ . Materials with this composition have been found to be nonsuperconducting, but superconductivity has been induced by one or more of the following methods: Ca substitutions at the Y site; Ba substitutions at the Sr site; annealing in high-pressure oxygen. The influence of these chemical manipulations onT c has been monitored and all methods have been found to enhanceT c . The electronic effects of Ba substitutions have been deduced indirectly using powder neutron diffraction, and such substitutions appear to result in a redistribution of hole density into the Cu(1) sites from the superconducting CuO2 planes. 相似文献
9.
10.
A.Varada Rajulu G. Babu Rao B. Ravi Prasad Rao A. Madhu Sudana Reddy Jiasong He Jun Zhang 《应用聚合物科学杂志》2002,84(12):2216-2221
Studies on some properties such as the density, the degradation temperatures, the morphology and the spectral features of the ligno‐cellulose fiber Hildegardia were carried out in both untreated and alkali treated form. The fibers are found to have good morphology and moderate initial and final degradation temperatures. On alkali treatment, the lignin was found to be eliminated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2216–2221, 2002 相似文献