全文获取类型
收费全文 | 653篇 |
免费 | 23篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 164篇 |
金属工艺 | 6篇 |
机械仪表 | 10篇 |
建筑科学 | 9篇 |
矿业工程 | 5篇 |
能源动力 | 43篇 |
轻工业 | 71篇 |
水利工程 | 5篇 |
石油天然气 | 6篇 |
无线电 | 70篇 |
一般工业技术 | 163篇 |
冶金工业 | 47篇 |
原子能技术 | 2篇 |
自动化技术 | 74篇 |
出版年
2024年 | 7篇 |
2023年 | 19篇 |
2022年 | 46篇 |
2021年 | 50篇 |
2020年 | 34篇 |
2019年 | 33篇 |
2018年 | 62篇 |
2017年 | 32篇 |
2016年 | 36篇 |
2015年 | 13篇 |
2014年 | 25篇 |
2013年 | 26篇 |
2012年 | 24篇 |
2011年 | 37篇 |
2010年 | 23篇 |
2009年 | 25篇 |
2008年 | 31篇 |
2007年 | 18篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 7篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
排序方式: 共有684条查询结果,搜索用时 0 毫秒
81.
Dr. M. Kumari 《Acta Mechanica》1987,66(1-4):61-81
Summary The unsteadely laminar incompressible second-order boundary-layer flow at the stagnation point of a three-dimensional body has been studied for both nodal and saddle point regions. The effects of mass transfer and Prandtl number have been taken into account. The equations governing the flow have been solved numerically using an implicit finite-difference scheme. It has been found that the parameter characterizing the unsteadiness in the velocity of the free stream, the nature of the stagnation point, the mass transfer and Prandtl number strongly affect the second-order skin friction and heat transfer. The overall skin friction becomes less due to second-order effects but the heat transfer has the opposite behaviour. For large injection, the second-order skin-friction and heat-transfer results prevail over the first-order boundary layer results whereas for the case of large suction the behaviour is just the opposite.With 14 Figures 相似文献
82.
83.
P. Koshy L. Prasanna Kumari M. T. Sebastian 《Journal of Materials Science: Materials in Electronics》1998,9(1):43-45
Ba3Ln3Ti5Nb5O30 (Ln=La, Nd) ceramics were prepared by the conventional solid-state ceramic route. The sintered samples were characterized by X-ray diffraction and scanning electron microscopy (SEM) methods. They have high dielectric constants, 141 and 203 at 13 MHz for La-based and Nd-based ceramics, respectively. The loss factor of the ceramics increases with frequency. 相似文献
84.
85.
The flow, heat and mass transfer on the unsteady laminar incompressible boundary layer in micropolar fluid at the stagnation point of a 2-dimensional and an axisymmetric body have been studied when the free stream velocity and the wall temperature vary arbitrarily with time. The partial defferential equations governing the flow have been solved numerically using a quasilinear finite-difference scheme. The skin friction, microrotation gradient and heat transfer parameters are found to be strongly dependent on the coupling parameter, mass transfer and time, whereas the effect of the microrotation parameter on the skin friction and heat transfer is rather weak, but microrotation gradient is strongly affected by it. The Prandtl number and the variation of the wall temperature with time affect the heat-transfer very significantly but the skin friction and micrortation gradient are unaffected by them. 相似文献
86.
After burn or resection of one submandibular salivary gland the contralateral gland responded by an increase of proliferation. The maximal mitotic index was observed 48 hours after the resection and 72 hours after the burn. Burn of the salivary gland initiated a stable, but weak compensatory hypertrophy of the contralateral gland. Hypertrophy of the gland was accompanied by an increase in the size of the cells and the nuclei whose area enlarged by 10 and 17%, respectively. Resection of the salivary gland caused an increase in the weight of the intact contralateral gland only at the early periods of the experiment. By the 30th and the 45th day after the operation the weight of the intact contralateral gland failed to differ from control. The detected differences in the compensatory growth of the intact glands in two types of action on the contralateral salivary gland depended on the quantity of the tissue degeneration products and on the period of their stay in the organism. 相似文献
87.
The sintering behaviour of lanthanum chromite with the addition of 1 to 3 wt% TiO2 was studied. Densification was examined as a function of sintering temperature and TiO2 concentration. The results showed that pure LaCrO3 could not be densified to >75% of the theoretical density, while the densities exceeding 90% of the theoretical were achieved
with 3 wt% titania addition at 1600° C.
Metallographic study reveals a normal grain growth following the rate equationD
2−D
0
2
=kt. Activation energies both for densification and grain growth have been estimated to be ≈ (80±5) k cal/mole in case of 3 wt%
TiO2 addition. 相似文献
88.
89.
Clinical course of multiple myeloma in patients under 40 years of age was analysed. In all cases diagnosis was established in III stage of the disease according to Durie and Salmon. In 4 cases good response to treatment (partial remission or stabilisation of proliferative process) was achieved. Survival time of 2 dead patients was 5 and 74 months, and that of 3 still alive patients is 41, 53, and 59 months and tends to be longer than median survival time of general population of patients with multiple myeloma. 相似文献
90.
An approach to tackle protein-calorie malnutrition through domiciliary management is described. Children suffering from moderate and severe protein-calorie malnutrition were managed using a food supplement containing low cost locally available foodstuffs and nutrition education. An evaluation showed that the anthropometric improvement was closely associated with better concepts in nutrition and improved dietary practices following nutrition education. Parents of children suffering from kwashiorkor had better knowledge and practice compared with those of marasmus. 相似文献