全文获取类型
收费全文 | 1497篇 |
免费 | 117篇 |
国内免费 | 557篇 |
专业分类
电工技术 | 10篇 |
综合类 | 5篇 |
化学工业 | 442篇 |
金属工艺 | 68篇 |
机械仪表 | 17篇 |
建筑科学 | 44篇 |
矿业工程 | 3篇 |
能源动力 | 19篇 |
轻工业 | 249篇 |
水利工程 | 19篇 |
石油天然气 | 103篇 |
武器工业 | 32篇 |
无线电 | 65篇 |
一般工业技术 | 230篇 |
冶金工业 | 227篇 |
原子能技术 | 533篇 |
自动化技术 | 105篇 |
出版年
2024年 | 5篇 |
2023年 | 13篇 |
2022年 | 40篇 |
2021年 | 59篇 |
2020年 | 41篇 |
2019年 | 41篇 |
2018年 | 48篇 |
2017年 | 43篇 |
2016年 | 51篇 |
2015年 | 26篇 |
2014年 | 63篇 |
2013年 | 89篇 |
2012年 | 101篇 |
2011年 | 125篇 |
2010年 | 64篇 |
2009年 | 69篇 |
2008年 | 74篇 |
2007年 | 73篇 |
2006年 | 86篇 |
2005年 | 67篇 |
2004年 | 77篇 |
2003年 | 46篇 |
2002年 | 58篇 |
2001年 | 36篇 |
2000年 | 28篇 |
1999年 | 22篇 |
1998年 | 29篇 |
1997年 | 30篇 |
1996年 | 16篇 |
1995年 | 17篇 |
1994年 | 13篇 |
1993年 | 116篇 |
1992年 | 25篇 |
1991年 | 85篇 |
1990年 | 73篇 |
1989年 | 58篇 |
1988年 | 74篇 |
1987年 | 75篇 |
1986年 | 88篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有2171条查询结果,搜索用时 15 毫秒
201.
Alice V Mkanda Amanda Minnaar Henriëtte L de Kock 《Journal of the science of food and agriculture》2007,87(15):2868-2879
BACKGROUND: Dry beans (Phaseolus vulgaris) have a range of varieties, colours and sizes. Differences in physicochemical and sensory properties influence consumer choices for beans. This study related consumer preferences to sensory and physico‐chemical properties of selected bean varieties—Jenny, Kranskop, PAN 148, AC Calmont, PAN 150 and Mkuzi—grown in Mpumalanga (MP) and Free State (FS) in South Africa. RESULTS: Significant (P < 0.05) variety, location as well as location × variety interaction effects were found for both physico‐chemical and sensory properties of beans. Jenny‐FS, Mkuzi and PAN 148‐MP beans had relatively long cooking times (>60 min). Some beans (e.g. PAN 150 and Mkuzi beans) were described as bitter, soapy and metallic with a raw‐bean flavour whereas more preferred beans (e.g. Jenny‐MP, Kranskop‐MP) were sweet, soft and with a cooked‐bean flavour. CONCLUSION Apart from small seed size, sensory characteristics such as bitter taste, soapy and metallic mouthfeel and hard texture contributed to consumers' dislike of certain bean varieties. The sweet taste, cooked‐bean flavours, soft and mushy textures of the most accepted varieties seemed to be related to beans with good hydration capacities that facilitated softening during cooking. Copyright © 2007 Society of Chemical Industry 相似文献
202.
“层位控制法”速度场在巨厚盐丘覆盖区的应用 总被引:3,自引:1,他引:2
肯基亚克盐下石炭系具有良好的油气勘探、开发前景。钻探及研究成果表明石炭系油气分布在很大程度上受控于构造。由于该区石炭系目的层埋深大(超过3500m),特别是上覆二叠系巨厚盐丘造成速度横向、纵向剧烈变化,从而导致石炭系构造畸变。采用以往的速度研究方法编制的构造图与实际钻探深度差异较大,造成钻探结果与构造图经常出现不符合现象,难以满足精细构造解释的需要。本文从地震资料研究入手,通过对盐丘非纯岩盐段反射能量与盐丘层速度统计分析,得到了非纯岩盐段反射能量与层速度的统计关系,应用“层位控制法”的速度建场方法建立速度场。用此方法编制的构造图消除了盐丘对下伏构造的影响,与随后钻井数据的吻合程度较高,为下一步勘探、开发提供了可靠的基础资料。 相似文献
203.
弹性波阻抗反演是一种结合了常规声阻抗反演和叠前AVO反演的地震反演技术。本文通过对不同的模型进行试算,分析比较了Connolly,Whitcombe等和Verwest等提出的三种弹性波阻抗公式。研究结果表明,由VerwestEI公式计算得到的反射系数比其他两种EI公式求得的反射系数精度高。与其他两种弹性波阻抗相比,VerwestEI可以作为更好的岩性指示器指导岩性和流体预测。 相似文献
204.
一、程序移植目的1.模拟动力堆燃料元件单棒稳态运行性能供燃料元件单棒的设计和运行参考我国反应堆燃料性能程序研究起步较晚,移植美国NRC经过多年发展和校验的标准程序有利于我国动力堆燃料元件的设计、制造和运行方面的研究,对发展我国轻水堆燃料元件稳态性能程序有一定参考价值。 相似文献
205.
Najavits Lisa M.; Ghinassi Frank; Van Horn Amanda; Weiss Roger D.; Siqueland Lynne; Frank Arlene; Thase Michael E.; Luborsky Lester 《Canadian Metallurgical Quarterly》2004,41(1):26
Ratings by 44 therapists in 4 modalities (cognitive, supportive-expressive, individual drug counseling, and group drug counseling) were obtained during one of the largest outcome trials ever conducted, the National Collaborative Cocaine Treatment Study. Views of the treatments, desired changes, and influences on implementation were studied. Therapists were highly positive about the treatments. However, their likelihood of using them in the future without modification was low, and they viewed them as too short. Supervision was perceived as more important than manuals and taping of sessions as more important than adherence scales. It took therapists an average of 8 months to feel comfortable with the treatments. New learning was therapists' primary motivation, more than extrinsic factors such as pay. Supportive-expressive therapists reported the most negative views, among modalities. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
206.
Zhou Lian-di Gao Qiu-xinChina Ship Scientific Research Center P. O. Box Wuxi P. R. China 《水动力学研究与进展(B辑)》1998,(1)
In this paper the complex structure and pattern of ship stern flow driven by multi-propellers is simulated numerically by using RANS equations with K-ε turbulence model and propeller lifting surface theory as essential research tool and coupling the computer code of ship stern flow to the computer code of propeller performance prediction through the medium of body force.A ship model with four propellers is selected as the numerical example.Detailed computational results are presented graphically and the qualitative and quantitative analysis is made. Finally,the comparison between the calculated result and the available experimental data is made.The agreement between them is satisfactory. 相似文献
207.
208.
方向导数法三维P—R分裂偏移 总被引:1,自引:1,他引:0
王振华 《石油地球物理勘探》1992,27(2):174-181
本文提出一种新的三维波动方程 P-R 分裂偏移方法,即方向导数法三维 P-R 分裂偏移方法。该方法在 Clearbout 浮动时间坐标中采用一种特殊的平行四边形网格及其相应的差分格式,来逼近三维波动方程中关于τ和 t 的二阶偏导数项(即方向导数项),而不事先对三维波动方向作任何近似,最后可得到一个与15°三维 P-R 分裂偏移在形式上完全相同的三维差分方程。这种方法在所有方位角上都具有波场全倾角归位特性,具有计算量与15°三维 P-R 分裂偏移方法相当,克服了15°三维 P-R 分裂偏移方法只适应地层倾角较小的缺点和45°旋转坐标系下全倾角三维 P-R 分裂偏移方法计算量较大的缺点,从而更具有应用价值。 相似文献
209.
Gathercole Susan E.; Hitch Graham J.; Service Elisabet; Martin Amanda J. 《Canadian Metallurgical Quarterly》1997,33(6):966
Sixty-five 5-year old children participated in 4 experimental tasks of word learning that varied systematically in the amounts of phonological and nonphonological learning required. Measures of the children's performances on 2 measures of phonological memory (digit span and nonword repetition), vocabulary knowledge, and nonverbal ability were also obtained. Learning of the sound structures of new words was significantly, and to some degree independently, associated with aspects of both phonological memory skill and vocabulary knowledge. Learning of pairs of familiar words was linked with current vocabulary knowledge, although not with phonological memory scores. The findings suggest that both existing lexical knowledge and phonological short-term memory play significant roles in the long-term learning of the sounds of new words. The study also provides evidence of both shared and distinct processes contributing to nonword repetition and digit span tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
210.