全文获取类型
收费全文 | 6216篇 |
免费 | 357篇 |
国内免费 | 25篇 |
专业分类
电工技术 | 82篇 |
综合类 | 23篇 |
化学工业 | 1678篇 |
金属工艺 | 119篇 |
机械仪表 | 149篇 |
建筑科学 | 266篇 |
矿业工程 | 15篇 |
能源动力 | 214篇 |
轻工业 | 732篇 |
水利工程 | 50篇 |
石油天然气 | 35篇 |
武器工业 | 2篇 |
无线电 | 499篇 |
一般工业技术 | 952篇 |
冶金工业 | 602篇 |
原子能技术 | 58篇 |
自动化技术 | 1122篇 |
出版年
2024年 | 9篇 |
2023年 | 47篇 |
2022年 | 229篇 |
2021年 | 281篇 |
2020年 | 141篇 |
2019年 | 144篇 |
2018年 | 202篇 |
2017年 | 191篇 |
2016年 | 227篇 |
2015年 | 161篇 |
2014年 | 225篇 |
2013年 | 413篇 |
2012年 | 344篇 |
2011年 | 421篇 |
2010年 | 302篇 |
2009年 | 336篇 |
2008年 | 312篇 |
2007年 | 286篇 |
2006年 | 266篇 |
2005年 | 214篇 |
2004年 | 169篇 |
2003年 | 176篇 |
2002年 | 146篇 |
2001年 | 105篇 |
2000年 | 96篇 |
1999年 | 86篇 |
1998年 | 208篇 |
1997年 | 135篇 |
1996年 | 130篇 |
1995年 | 94篇 |
1994年 | 60篇 |
1993年 | 69篇 |
1992年 | 26篇 |
1991年 | 32篇 |
1990年 | 24篇 |
1989年 | 25篇 |
1988年 | 15篇 |
1987年 | 21篇 |
1986年 | 21篇 |
1985年 | 22篇 |
1984年 | 15篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 18篇 |
1980年 | 13篇 |
1979年 | 19篇 |
1978年 | 14篇 |
1977年 | 16篇 |
1976年 | 25篇 |
1971年 | 7篇 |
排序方式: 共有6598条查询结果,搜索用时 15 毫秒
51.
52.
Gene expression microarray is a rapidly maturing technology that provides the opportunity to assay the expression levels of thousands or tens of thousands of genes in a single experiment. We present a new heuristic to select relevant gene subsets in order to further use them for the classification task. Our method is based on the statistical significance of adding a gene from a ranked-list to the final subset. The efficiency and effectiveness of our technique is demonstrated through extensive comparisons with other representative heuristics. Our approach shows an excellent performance, not only at identifying relevant genes, but also with respect to the computational cost. 相似文献
53.
54.
55.
F. La Via G. Galvagno F. Giannazzo A. Ruggiero L. Calcagno M. Mauceri G. Pistone G. Abbondanza A. Veneroni L. Zamolo G.L. Valente 《Microelectronic Engineering》2006,83(1):48-50
The results of a new epitaxial process using an industrial 6 × 2″ wafer reactor with the introduction of HCl during the growth have been reported. A complete reduction of silicon nucleation in the gas phase has been observed even for high silicon dilution parameters (Si/H2 > 0.05%) and an increase of the growth rate until about 20 μm/h has been measured. Photoluminescence at room temperature and at 50 K was used for defects quantification and distribution. On these wafers grown using HCl high voltage Schottky diodes have been realized. The diodes were analyzed by current-voltage (I-V) characteristics. 相似文献
56.
57.
Antonio M. Locci Roberto Orrù Giacomo Cao Zuhair A. Munir 《Journal of the American Ceramic Society》2006,89(3):848-855
The simultaneous synthesis and densification of dense TiC–TiB2 composite has been investigated starting from Ti, B4 C, and C as reactants, and using the spark plasma sintering (SPS) technique. The optimal conditions for complete conversion of the reactants to the composite were determined for different applied DC current levels. A kinetic investigation performed allows us to conclude that solid-state diffusion is the mechanism governing the synthesis process. It is seen that TiC is the first phase formed, while TiB2 formation occurs afterward. Two intermediate boride phases, i.e. TiB and Ti3 B4 , are also formed but, as the SPS holding time was augmented, they were gradually and completely converted to TiB2 . Moreover, it is found that in order to reach relatively high dense products, an electric current needs to be applied for time intervals longer than those required for obtaining complete conversion. A pure dense product (relative density ∼98%) was obtained when an electric pulsed current of 1100 A and a mechanical pressure of 20 MPa were applied for about 4 min. 相似文献
58.
Oscar A. Garro Emilio Rodríguez Roberto Palacios Unda Danley A. S. Callieri 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(4):367-373
The kinetics of alcoholic fermentation of a strain of Zymomonas mobilis, isolated from sugarcane juice, has been studied with the objective of determining the constansts of a non-structured mathematical model that represents the fermentation process. Assays in batch and in continuous culture have been carried out with different initial concentrations of glucose. The final concentrations of glucose, ethanol and biomass were determined. The following kinetic parameters were obtained: μmax, 0·5 h?1; Ks, 4·64 g dm?3; Pmax, 106 g dm?3; Yx/s, 0·0265 g g?1; m, 1·4 g g?1 h?1; α, 17·38 g g?1; β, 0·69 g g?1 h?1. 相似文献
59.
60.
DD De La Tour D Raccah MF Jannot T Coste C Rougerie P Vague 《Canadian Metallurgical Quarterly》1998,41(9):1080-1084
The purpose of this study is to clarify the volume effect of epidural saline injection 20 min after spinal anesthesia. Thirty patients undergoing combined spinal and epidural anesthesia for orthopedic surgery were randomly divided into two groups: a control group (n = 15) and a saline group (n = 15). In the control group, 2% lidocaine 3 ml with 0.4% tetracaine was injected into the subarachnoid space from L 4-5 interspace using Durasafe (Becton Dickinson, USA) and saline was not injected into the epidural space. In the saline group, saline 10 ml was injected through an epidural catheter 20 min after spinal anesthesia. The levels of analgesia 20 min after spinal anesthesia were not significantly different between the groups. However, the levels of analgesia 3, 5, 10, 40 and 100 min after epidural saline injection in the saline group were significantly higher than those in the control group (P < 0.05). The highest analgesic level was obtained 10 min after epidural saline injection and reached to T 4.3 +/- 1.1. In conclusion, epidural saline injection increases the analgesic level 20 min after spinal anesthesia because of the volume effect. 相似文献