全文获取类型
收费全文 | 2164篇 |
免费 | 15篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 152篇 |
金属工艺 | 65篇 |
机械仪表 | 25篇 |
建筑科学 | 67篇 |
矿业工程 | 2篇 |
能源动力 | 17篇 |
轻工业 | 110篇 |
水利工程 | 11篇 |
石油天然气 | 2篇 |
无线电 | 125篇 |
一般工业技术 | 183篇 |
冶金工业 | 1237篇 |
原子能技术 | 4篇 |
自动化技术 | 167篇 |
出版年
2022年 | 10篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2017年 | 17篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 14篇 |
2013年 | 52篇 |
2012年 | 40篇 |
2011年 | 56篇 |
2010年 | 29篇 |
2009年 | 29篇 |
2008年 | 44篇 |
2007年 | 48篇 |
2006年 | 39篇 |
2005年 | 34篇 |
2004年 | 26篇 |
2003年 | 36篇 |
2002年 | 30篇 |
2001年 | 26篇 |
2000年 | 31篇 |
1999年 | 55篇 |
1998年 | 343篇 |
1997年 | 192篇 |
1996年 | 132篇 |
1995年 | 86篇 |
1994年 | 75篇 |
1993年 | 69篇 |
1992年 | 24篇 |
1991年 | 17篇 |
1990年 | 41篇 |
1989年 | 28篇 |
1988年 | 34篇 |
1987年 | 20篇 |
1986年 | 37篇 |
1985年 | 37篇 |
1984年 | 16篇 |
1983年 | 18篇 |
1982年 | 28篇 |
1981年 | 29篇 |
1980年 | 38篇 |
1979年 | 21篇 |
1978年 | 19篇 |
1977年 | 27篇 |
1976年 | 58篇 |
1975年 | 15篇 |
1974年 | 15篇 |
1973年 | 14篇 |
1968年 | 8篇 |
排序方式: 共有2181条查询结果,搜索用时 15 毫秒
21.
22.
23.
The excitation coefficients of modes in a circular corrugated waveguide that arise when dominant modes are incident from a cluster of four square waveguides are calculated. Mono-pulse-like radiation patterns arise when modes in the input guides are appropriately phased. Factors influencing the crosspolar performance of the feed are discussed, and the dependence of the excitation coefficients on waveguide and junction parameters is predicted. 相似文献
24.
KA Elliott 《Canadian Metallurgical Quarterly》1998,23(3):44-6,49-53
Epidemiologic studies have demonstrated a continuing increase in the prevalence of vulvovaginal candidiasis. Although in the past most of these infections were caused by Candida albicans, an increasing percentage are caused by non-albicans Candida species that are less sensitive to the most frequently used antifungal agents. An accurate diagnosis of these infections and the subsequent choice of the most appropriate therapy can only be made after a thorough evaluation of the patient. Successful treatment of vulvovaginal candidiasis is dependent on compliance with therapy; thus, the treatment regimen chosen should fit the patient's daily lifestyle. Newer single-dose regimens offer the option of completing therapy with a single treatment for most patients with uncomplicated vaginal candidiasis. Use of topical agents avoids the potential systemic adverse effects and drug interactions that have been noted with oral antifungals. Patient education and support can also enhance satisfaction with the treatment plan and promote compliance. 相似文献
25.
In this paper, the authors describe how the tragic events of 11 September 2001 have resulted in an urgent requirement for improved and enhanced security measures at airports, larger facilities and transportation networks. 相似文献
26.
27.
Spruce wood residues were treated in a vacuum pyrolysis Process Development Unit with a throughput capacity of 28 kg/h. Two aqueous phase condensate samples with COD concentration varying between 190 and 255 g/L were produced and sequentially extracted with dichloromethane and ethylacetate solvents. The soluble organic matter was composed of acidic, phenolic, alcoholic and ketonic compounds. The insoluble fraction was sequentially distilled at 100 and 110°C under atmospheric pressure. Mainly water was recovered in the first distillate, while the second distillate contained 30.4% formic and acetic acids, 69.4% water and 0.2% residual organic compounds. The distillation residue was rich in oxygen and was essentially insoluble in any organic solvent. The two aqueous phase pyroligneous samples were treated in Bat-telle's Thermochemical Environmental Energy System (TEESr?), a registered service mark of Onsite*Ofsite, Inc. of Duarte, California, U.S.A. The results of the tests showed that similar results were obtained with either feedstock. In batch tests a COD reduction of 99% was achieved. The product gas composition was typically about 49% methane, 5% hydrogen, 1 % ethane and 45% carbon dioxide. Tests in a continuous stirred-tank reactor produced reproducible data which can be used for process scale-up. Catalyst lifetime was identified as needing further improvement. The preliminary results demonstrated the technical feasibility of the catalytic gasification process as a useful step in the recovery of energy from the secondary condensate stream and the cleanup of the by-product water from vacuum pyrolysis of wood. 相似文献
28.
29.
Brandon T. L. Elliott D. G. Cockburn B. F. 《IEEE transactions on circuits and systems. I, Regular papers》2006,53(12):2595-2605
ROM cell architectures are proposed that have roughly 20% greater storage density in the cell array compared to that of a conventional ROM. Increased density is achieved by exploiting the multiple interconnect layers now available in common logic processes and by using multiple ROM cell types in combination. The storage density of arrays of these hybrid ROM cells increases further as more interconnect layers become available. In addition, a new SRAM-ROM architecture is presented that capitalizes on these techniques to add ROM capability to a conventional SRAM cell with no additional transistors in the memory cell and little or, in some cases, no impact on the cell area 相似文献
30.
Frank J.Elliott 《中国计算机用户》2003,(5):26-26
众所周知,在当前的企业信息系统中,一些新型的应用、无法预料的业务需求、加上信息传递和访问渠道的增多,使得企业需要存储的数据信息量呈爆炸性增长。应对这些问题,是一项艰巨而又昂贵的工作,尤其是存储及处理大量重要的商业信息。对于存储,很多信息系统决策者已经认识到了它的重要性。但是,高昂的花销却让决策者“瞻前顾后”、左右为难。如何才能制订一个最合适的规划呢?IBM存储产品部副总裁Frank J.Elliott为我们展示了他的分析。 相似文献