全文获取类型
收费全文 | 98246篇 |
免费 | 7525篇 |
国内免费 | 4222篇 |
专业分类
电工技术 | 5435篇 |
技术理论 | 7篇 |
综合类 | 6608篇 |
化学工业 | 17049篇 |
金属工艺 | 6007篇 |
机械仪表 | 6059篇 |
建筑科学 | 8581篇 |
矿业工程 | 2857篇 |
能源动力 | 2675篇 |
轻工业 | 5912篇 |
水利工程 | 1792篇 |
石油天然气 | 5630篇 |
武器工业 | 758篇 |
无线电 | 10209篇 |
一般工业技术 | 11753篇 |
冶金工业 | 4929篇 |
原子能技术 | 1197篇 |
自动化技术 | 12535篇 |
出版年
2024年 | 381篇 |
2023年 | 1594篇 |
2022年 | 2599篇 |
2021年 | 3611篇 |
2020年 | 2841篇 |
2019年 | 2386篇 |
2018年 | 2727篇 |
2017年 | 3069篇 |
2016年 | 2687篇 |
2015年 | 3540篇 |
2014年 | 4483篇 |
2013年 | 5462篇 |
2012年 | 5984篇 |
2011年 | 6400篇 |
2010年 | 5456篇 |
2009年 | 5407篇 |
2008年 | 5262篇 |
2007年 | 5028篇 |
2006年 | 5342篇 |
2005年 | 4684篇 |
2004年 | 3308篇 |
2003年 | 3104篇 |
2002年 | 3309篇 |
2001年 | 2800篇 |
2000年 | 2725篇 |
1999年 | 2913篇 |
1998年 | 2315篇 |
1997年 | 1878篇 |
1996年 | 1926篇 |
1995年 | 1569篇 |
1994年 | 1263篇 |
1993年 | 894篇 |
1992年 | 739篇 |
1991年 | 577篇 |
1990年 | 426篇 |
1989年 | 360篇 |
1988年 | 292篇 |
1987年 | 188篇 |
1986年 | 133篇 |
1985年 | 95篇 |
1984年 | 66篇 |
1983年 | 42篇 |
1982年 | 43篇 |
1981年 | 36篇 |
1980年 | 29篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1971年 | 1篇 |
1965年 | 3篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
In this paper, genetic algorithm is used to help improve the tolerance of feedforward neural networks against an open fault. The proposed method does not explicitly add any redundancy to the network, nor does it modify the training algorithm. Experiments show that it may profit the fault tolerance as well as the generalisation ability of neural networks. 相似文献
52.
In CFD simulation of diesel combustion, the predictive capabilities of the spray model play the most important role. Consequently, under the strict guidelines of the V&V, a method to adjust parameters of diesel spray model WAVE to accompany with the in-cylinder physical progress has been investigated in this paper. Moreover, the simulation of the spray has been validated by high-speed photography experiments and verified by the equation proposed by Hiroyasu. Finally, a modified setup for the WAVE spray model has been proposed and applied in the spray and combustion simulation for Deutz1013 diesel in different engine speed. 相似文献
53.
Defeng Wu Yisheng Zhang Lanfeng Wu Lifeng Jin Ming Zhang Weidong Zhou Changhao Yan 《应用聚合物科学杂志》2008,108(3):1934-1941
Polyarylene ether nitriles (PEN)/thermotropic liquid crystalline polymer (TLCP) blend was prepared via melt mixing. The immiscible phase morphologies, linear and nonlinear, as well as transient viscoelastic properties of the blend were studied using SEM, rheometer, and DMA. The linear dynamic viscoelastic behavior of the blend shows temperature dependence due to further evolution of the immiscible morphology and, as a result, the principle of time‐temperature superposition (TTS) is invalid. In the steady shear flow, the discrete TLCP phase is difficult to be broken up because of the high viscosity ratio of the blend systems, while is easy to be coarsened and followed by elongation, and finally, to form fibrous morphology at high TLCP content and high shear level. During this morphological evolution process, the transient stress response presents step increase and nonzero residual relaxation behavior, leading to increase of the dynamic viscoelastic responses after steady preshear. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
54.
A novel monomer containing pyridylazo-2-naphthoxyl group, 1-(1-(4-vinylbenzyloxy)naphthalen-2-yl)-2-(pyridin-2-yl)diazene (VBNPA), was successfully synthesized and copolymerized with styrene (St) in N,N-dimethyl formamide (DMF) via reversible addition–fragmentation chain transfer (RAFT) polymerization using 2-cyanoprop-2-yl-1-dithionaphthalate (CPDN) as RAFT agent. The polymerization behavior exhibited “living”/controlled characters. The obtained copolymer, poly(St-co-VBNPA), with pre-determinable molecular weight and narrow molecular weight distribution can be used as a carrier in metal ion detection and analysis via pre-concentration technique. The copolymer–metal ion (copper (Cu) and europium (Eu)) complexes were prepared and characterized. 相似文献
55.
56.
57.
An analytical method is presented for calculating the resonant frequency andQ-factor of a superconducting dielectric disk resonator operating in millimeter-wave regime with whispering-gallery mode. Resonant frequency shift due to the optical generation of quasi-particles in superconducting film is investigated as a function of photon flux. An optically tunable resonant frequency of about 500 MHz is estimated, and good agreement is found between numerical results and experimental ones. 相似文献
58.
PURPOSE: The purpose of this research is to obtain the tablet coating distribution from weight distributions of uncoated and coated tablets. METHODS: The method of deconvolution with digital smoothing was used to calculate the distribution of coating applied to a tablet population from separate random measurements of individual uncoated and coated tablets. RESULTS: It was demonstrated that the calculated coating weight distribution agrees well with the measured distribution. The effect of the smoothing factor on the solution is illustrated. CONCLUSIONS: This method can be used during development to facilitate process scale-up/optimization. In routine production, the method can assess the reproducibility and consistency of a coating process. 相似文献
59.
Conventional drying, dehumidification drying, and combined conventional-dehumidification drying of wood were experimentally studied in this article. The results showed that the energy consumption in the dehumidification drying is the least but its drying time is the longest. The energy consumption in the combined drying is more than that in the dehumidification drying but less than that in the conventional drying, and the drying time is half of that in the dehumidification drying. The advantages of the combined conventional and dehumidification drying are discussed from the experiments results. 相似文献
60.