全文获取类型
收费全文 | 167272篇 |
免费 | 17328篇 |
国内免费 | 11859篇 |
专业分类
电工技术 | 15002篇 |
技术理论 | 3篇 |
综合类 | 22540篇 |
化学工业 | 16317篇 |
金属工艺 | 6694篇 |
机械仪表 | 12792篇 |
建筑科学 | 19198篇 |
矿业工程 | 7486篇 |
能源动力 | 5405篇 |
轻工业 | 8493篇 |
水利工程 | 7235篇 |
石油天然气 | 6598篇 |
武器工业 | 2453篇 |
无线电 | 11481篇 |
一般工业技术 | 19721篇 |
冶金工业 | 6139篇 |
原子能技术 | 2354篇 |
自动化技术 | 26548篇 |
出版年
2024年 | 700篇 |
2023年 | 1929篇 |
2022年 | 3684篇 |
2021年 | 4283篇 |
2020年 | 4968篇 |
2019年 | 4349篇 |
2018年 | 4227篇 |
2017年 | 5293篇 |
2016年 | 5936篇 |
2015年 | 6250篇 |
2014年 | 10047篇 |
2013年 | 9812篇 |
2012年 | 12763篇 |
2011年 | 13187篇 |
2010年 | 10189篇 |
2009年 | 10594篇 |
2008年 | 9974篇 |
2007年 | 12393篇 |
2006年 | 10885篇 |
2005年 | 9174篇 |
2004年 | 7462篇 |
2003年 | 6438篇 |
2002年 | 5334篇 |
2001年 | 4478篇 |
2000年 | 3980篇 |
1999年 | 3394篇 |
1998年 | 2679篇 |
1997年 | 2256篇 |
1996年 | 1874篇 |
1995年 | 1681篇 |
1994年 | 1400篇 |
1993年 | 1010篇 |
1992年 | 894篇 |
1991年 | 628篇 |
1990年 | 510篇 |
1989年 | 528篇 |
1988年 | 370篇 |
1987年 | 210篇 |
1986年 | 166篇 |
1985年 | 71篇 |
1984年 | 73篇 |
1983年 | 45篇 |
1982年 | 46篇 |
1981年 | 57篇 |
1980年 | 32篇 |
1979年 | 39篇 |
1978年 | 17篇 |
1977年 | 18篇 |
1975年 | 16篇 |
1959年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
J. R. He G. C. I. Lin 《The International Journal of Advanced Manufacturing Technology》1992,7(4):210-217
A computerised trace method has been developed for determining the relationships of assembly requirements with design dimensions
and tolerances of the components in an assembly, and the relationships of design specifications and machining allowance requirements
with manufactured dimensions and tolerances of the component in a process plan. This method traces from the proposed components
or planned operations only the dimensions and tolerances that affect the given requirement, and therefore the equations for
design or for manufacture can be established simultaneously and accurately. Hence it is possible to establish constraints
for the optimisation of dimensions and tolerances for design or for manufacture. 相似文献
93.
Microstructure evolution during metal forming processes 总被引:8,自引:0,他引:8
Recrystallization and grain growth evolutions during metal forming processes are considered. Coupling between the thermo-mechanical and microstructure processes is realized. Die forging of a rear-axle flange is simulated numerically on the base of the finite element method. Material parameters of the models are obtained experimentally. The influence of interpass and holding times on grain size distributions in the end product is shown. 相似文献
94.
本文先将倒虹吸管的管径计算公式整理成等式左边只含管径的一次方法,右边含有管径高阶非线性的迭代函数,然后证明该迭代函数收敛,最后利用数学迭代原理给迭代函数右边赋初值,计算左边的管径。继续迭代下去,就能求出倒虹吸管的管径。 相似文献
95.
This paper deals with a new boundary element method for analysis of the quasistatic problems in coupled thermoelasticity. Through some mathematical manipulation of the Navier equation in elasticity, the heat conduction equation is transformed into a simpler form, similar to the uncoupled-type equation with the modified thermal conductivity which shows the coupling effects. This procedure enables us to treat the coupled thermoelastic problems as an uncoupled one, A few examples are computed by the proposed BEM, and the results obtained are compared with the analytical ones available in the literature, whereby the accuracy and versatility of the proposed method are demonstrated. 相似文献
96.
对国内引进的、用于粉末冶金的步进梁式炉的运动,以图解法和解析法进行了分析,并对运动参数进行了理论推导和计算。本研究结果,对解决步进粱式炉的运动故障以及进行新型设计提供了有效的理论分析和计算依据。 相似文献
97.
Tsuyoshi Takahashi Masahito Kitou Michio Asai Mitsuyasu Kido Tomio Chiba Junzou Kawakami Yoshiaki Matsui 《Electrical Engineering in Japan》1994,114(2):18-33
Power system control equipment needs higher sensitivity and operational reliability. Advanced voltage control equipment is needed for reducing the frequency of tap changes and improving the characteristics (the relationship between the actual voltage and reference voltage) of the voltage to meet today's power system requirements. However, these objectives are in a trade-off relationship. Studies of voltage control derived from a knowledge base suitable for electric power systems can satisfy these objectives using fuzzy inference. Compared with corresponding conventional equipment, the new equipment improved the deviation of 30 min average voltage of 30 percent. This paper describes the design concept of new voltage control equipment using fuzzy inference. In addition, field test results are described along with rules of fuzzy inference, membership functions, and the deviation of 30 min average voltage through detailed simulation. 相似文献
98.
Periklis E. Ergatis Panagiotis G. Massouros Georgia C. Athanasouli George P. Massouros 《国际能源研究杂志》2003,27(9):795-811
A time‐dependent coefficient of heat transfer is proposed for the computation of thermal power required, so that a room temperature reaches a desired value within a given time. A mathematical formulation of the room heating transient phenomenon is constructed in a dimensionless form. Using an integral approximate solution an analytical expression for this coefficient is provided and it is verified by diagrams adopted by DIN 4701. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
99.
Solving regularized least squares with qualitatively controlled adaptive cross‐approximated matrices
The adaptive cross‐approximation (ACA) technique is applied to accelerating an inverse‐problem solver that estimates charge distribution on a dielectric spacer. The ACA generates an approximated system‐matrix that enables us to carry out high‐speed inverse calculation. We designed an approximation procedure based on ACA with some additional concepts, that is, (a) partitioning of matrix based on algebraic information, (b) approximation quality control based on matrix norms, and so on. The tested solver (LSQR for regularized least squares) with ACA demonstrates about 10 times faster performance than that without ACA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(3): 10–18, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20326 相似文献
100.
T. Bag 《Information Sciences》2006,176(19):2910-2931
In this paper, definitions of strongly fuzzy convergent sequence, l-fuzzy weakly convergent sequence and l-fuzzy weakly compact set are given in a fuzzy normed linear space. The concepts of fuzzy normal structure, fuzzy non-expansive mapping, uniformly convex fuzzy normed linear space are introduced and fixed point theorems for fuzzy non-expansive mappings are proved. 相似文献