全文获取类型
收费全文 | 206493篇 |
免费 | 15515篇 |
国内免费 | 7837篇 |
专业分类
电工技术 | 11322篇 |
技术理论 | 14篇 |
综合类 | 11251篇 |
化学工业 | 35883篇 |
金属工艺 | 10592篇 |
机械仪表 | 12032篇 |
建筑科学 | 16463篇 |
矿业工程 | 4975篇 |
能源动力 | 5873篇 |
轻工业 | 12735篇 |
水利工程 | 3244篇 |
石油天然气 | 11130篇 |
武器工业 | 1356篇 |
无线电 | 25565篇 |
一般工业技术 | 26789篇 |
冶金工业 | 10958篇 |
原子能技术 | 2124篇 |
自动化技术 | 27539篇 |
出版年
2024年 | 890篇 |
2023年 | 3281篇 |
2022年 | 5889篇 |
2021年 | 7971篇 |
2020年 | 5841篇 |
2019年 | 5042篇 |
2018年 | 5439篇 |
2017年 | 6228篇 |
2016年 | 5722篇 |
2015年 | 7330篇 |
2014年 | 9552篇 |
2013年 | 12321篇 |
2012年 | 12261篇 |
2011年 | 13928篇 |
2010年 | 11660篇 |
2009年 | 11480篇 |
2008年 | 10914篇 |
2007年 | 10502篇 |
2006年 | 10882篇 |
2005年 | 9672篇 |
2004年 | 6589篇 |
2003年 | 5794篇 |
2002年 | 5267篇 |
2001年 | 4739篇 |
2000年 | 4894篇 |
1999年 | 5653篇 |
1998年 | 5300篇 |
1997年 | 4366篇 |
1996年 | 3968篇 |
1995年 | 3322篇 |
1994年 | 2771篇 |
1993年 | 2194篇 |
1992年 | 1704篇 |
1991年 | 1282篇 |
1990年 | 1023篇 |
1989年 | 883篇 |
1988年 | 682篇 |
1987年 | 496篇 |
1986年 | 395篇 |
1985年 | 334篇 |
1984年 | 213篇 |
1983年 | 198篇 |
1982年 | 164篇 |
1981年 | 145篇 |
1980年 | 132篇 |
1979年 | 97篇 |
1978年 | 63篇 |
1977年 | 63篇 |
1976年 | 77篇 |
1975年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
本文基于静态相关性分析和动态调整相结合的方法,提出了一种逻辑程序的执行模型,它不仅开发了“与“并行,同进也开发了一定的“或“并行,从而有效地加速了逻辑程序的执行。 相似文献
62.
Hsin-Li Chen Ching-Yuan Wu 《Electron Devices, IEEE Transactions on》1998,45(10):2245-2247
An analytical model for the grain-barrier height of the intrinsic poly-Si thin-film transistors (TFTs) is developed, in which the grain-barrier height for the applied gate voltage smaller than the threshold voltage is obtained by solving the charge neutrality equation and the grain-barrier height for the applied gate voltage larger than the threshold voltage is obtained by using the quasi-two-dimensional (2-D) method. Good agreements between experimental and simulation results are obtained for a wide gate voltage range 相似文献
63.
A technique for SiO2 formation by liquid-phase deposition (LPD) at nearly room temperature for low-temperature processed (LTP) polysilicon thin-film transistor (poly-Si TFT) was developed. LPD SiO2 film with a lower P-etch rate shows a dense structure. LPD SiO2 also exhibits good electrical characteristics. LTP poly-Si thin-film transistors (TFTs) with LPD SiO 2 as the gate insulator have been fabricated and investigated. Their characteristics indicate performance adequate for their use as pixel transistors in liquid crystal displays (LCDs) 相似文献
64.
In order to cumpare the peformance of different supply diffuers of ventilation air, the airflow passern, temperature stratifiation and contaminant dispersion in a furnitured office ventilated by three kinds of air diffuer were numerically investigated. The air diffuers studied in this paper are a quarter-cylinder displacement diffuer on the floor and mixing diffuers (linear and vortex diffuers) on the ceiling. The heat sources in the of-fice are considered to be 50% convective and 50% radiative. The k-? two-equatwn model of turbulence is employed to predict the turbulent diffusion. The results show that the displacement diffuser provides a rather uniform flow field with low velocify in most areas, and the vertical temperature difference from floor to ceiling is as high as 6 K. With the linear diffuser, the air velociry is high, and the temperature is uniform both horizontally and vertically. The air velocity generated by the vortex diffuser is moderate. The distributions of the temperature and the contaminant are rather uniform. 相似文献
65.
基数排序由于其效率高而被广泛应用。通常,基数排序所用的基数是10,然而,如果求得一个基数r_(best),并且用r_(best)为基数进行基数排序使排序时间达到最小,则这将具有非常重要的意义。本文给出了求r_(best)的方法,分析了以r_(best)为基数进行基数排序的时间复杂度,提出了进一步提高效率的措施,并将以r_(best)为基数的基数排序速度与以10为基数的基数排序进行了比较。 相似文献
66.
The augmented drift-diffusion current equation, which includes velocity overshoot effects through the space derivatives of the electric field, cannot be directly extended beyond one dimension. A new formalism is developed which considers the carrier heating and the distribution relaxation effects to obtain a multidimensional augmented drift diffusion current equation. The equivalent mobility containing the velocity overshoot correction is derived from the perturbation analysis on the carrier temperature using the energy balance equation. The issues related to the numerical implementation of this generalized model and the validity of the assumptions are also discussed 相似文献
67.
68.
It has been observed that herpes simplex virus mutants with deficient or altered thymidine kinase activity are more susceptible to Cidofovir (CDV; 1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine dihydrate) in tissue culture than are the parental strains. During infection of cells, the elevation of the dCTP pool by thymidine kinase mutant viruses is less than that induced by the wild-type virus. The competition between CDV diphosphate and dCTP at the viral polymerase is therefore changed in favor of CDV diphosphate, enhancing its activity. 相似文献
69.
We compared the data from four growth hormone (GH) immunoassays for analyzing 24-h GH profiles in four apparently normal subjects and four obese subjects (508 serum samples). The detection limit was 0.02 microgram/L for one immunochemiluminometric assay (ICMA), 0.1 microgram/L for two IRMAs, and 0.4 microgram/L for one RIA. All GH pulses with a peak ICMA value > 1 microgram/L were detected by each of the other methods. Overall, the correlation coefficient between the values obtained with all four assays exceeded 0.90. However, for GH concentrations < or = 0.25 microgram/L, acceptable concordance (r2 > or = 0.80) was reached only between the ICMA and one IRMA; between the ICMA and the RIA, concordance was acceptable only for GH concentrations > or = 10 micrograms/L. In the normal subjects, the percentage of undetectable values was 0% with the ICMA but 29% with one of the IRMAs; in obese subjects, the corresponding values were 12% and 38%. 相似文献
70.
应用音平化渣图象分析和指导转炉造渣操作 总被引:3,自引:1,他引:2
利用音平化渣图象可以清晰地看出在转炉造渣过程中何时发生喷溅,何时发生炉渣返干和何时化渣正常。应用音平化渣图象和炉渣三元相图,可以正确地分析发生喷溅和返干的原因,从而找到避免突发性喷溅和严重返干的方法。正确的枪位和炉渣碱度控制是实现平稳吹炼的保证,而音平化渣图象能帮助操作工实现这一目标。 相似文献