全文获取类型
收费全文 | 18141篇 |
免费 | 1423篇 |
国内免费 | 855篇 |
专业分类
电工技术 | 1308篇 |
技术理论 | 5篇 |
综合类 | 2828篇 |
化学工业 | 1466篇 |
金属工艺 | 416篇 |
机械仪表 | 1054篇 |
建筑科学 | 2997篇 |
矿业工程 | 647篇 |
能源动力 | 673篇 |
轻工业 | 1506篇 |
水利工程 | 742篇 |
石油天然气 | 1342篇 |
武器工业 | 161篇 |
无线电 | 640篇 |
一般工业技术 | 1852篇 |
冶金工业 | 1046篇 |
原子能技术 | 186篇 |
自动化技术 | 1550篇 |
出版年
2024年 | 103篇 |
2023年 | 330篇 |
2022年 | 460篇 |
2021年 | 506篇 |
2020年 | 563篇 |
2019年 | 442篇 |
2018年 | 417篇 |
2017年 | 481篇 |
2016年 | 556篇 |
2015年 | 552篇 |
2014年 | 1009篇 |
2013年 | 981篇 |
2012年 | 1276篇 |
2011年 | 1319篇 |
2010年 | 1017篇 |
2009年 | 1045篇 |
2008年 | 966篇 |
2007年 | 1267篇 |
2006年 | 1128篇 |
2005年 | 1041篇 |
2004年 | 842篇 |
2003年 | 738篇 |
2002年 | 634篇 |
2001年 | 520篇 |
2000年 | 431篇 |
1999年 | 348篇 |
1998年 | 273篇 |
1997年 | 245篇 |
1996年 | 182篇 |
1995年 | 161篇 |
1994年 | 106篇 |
1993年 | 87篇 |
1992年 | 71篇 |
1991年 | 70篇 |
1990年 | 53篇 |
1989年 | 42篇 |
1988年 | 38篇 |
1987年 | 19篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1977年 | 4篇 |
1961年 | 4篇 |
1957年 | 5篇 |
1956年 | 4篇 |
1955年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
51.
Sedikides Constantine; Gaertner Lowell; Toguchi Yoshiyasu 《Canadian Metallurgical Quarterly》2003,84(1):60
The culture movement challenged the universality of the self-enhancement motive by proposing that the motive is pervasive in individualistic cultures (the West) but absent in collectivistic cultures (the East). The present research posited that Westerners and Easterners use different tactics to achieve the same goal: positive self-regard. Study 1 tested participants from differing cultural backgrounds (the United States vs. Japan), and Study 2 tested participants of differing self-construals (independent vs. interdependent). Americans and independents self-enhanced on individualistic attributes, whereas Japanese and interdependents self-enhanced on collectivistic attributes. Independents regarded individualistic attributes, whereas interdependents regarded collectivistic attributes, as personally important. Attribute importance mediated self-enhancement. Regardless of cultural background or self-construal, people self-enhance on personally important dimensions. Self-enhancement is a universal human motive. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
52.
53.
Yoon Carolyn; Feinberg Fred; Hu Ping; Gutchess Angela Hall; Hedden Trey; Chen Hiu-Ying Mary; Jing Qicheng; Cui Yao; Park Denise C. 《Canadian Metallurgical Quarterly》2004,19(3):379
Understanding how aging influences cognition across different cultures has been hindered by a lack of standardized, cross-referenced verbal stimuli. This study introduces a database of such item-level stimuli for both younger and older adults, in China and the United States, and makes 3 distinct contributions. First, the authors specify which item categories generalize across age and/or cultural groups, rigorously quantifying differences among them. Second, they introduce novel, powerful methods to measure between-group differences in freely generated ranked data, the rank-ordered logit model and Hellinger Affinity. Finally, a broad archive of tested, cross-linguistic stimuli is now freely available to researchers: data, similarity measures, and all stimulus materials for 105 categories and 4 culture-by-age groups, comprising over 10,000 fully translated unique item responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
54.
Hussain Sheikha Anil K. Mehrotra Mehran Pooladi-Darvish 《Journal of Petroleum Science and Engineering》2006,53(3-4):189-202
An inverse solution methodology is developed for the estimation of diffusion coefficient of gases in highly viscous, oil-sands bitumens from isothermal, pressure-decay measurements. The approach involves modeling the rate of change in pressure using the diffusion equation for the liquid phase coupled with a mass balance equation for the gas phase. The inverse solution framework is utilized to arrive at two graphical techniques for estimating the diffusion coefficient. Both techniques involve the determination of the slope of a straight line resulting from plotting the experimental data in accordance with the developed model. An advantage of the proposed techniques is that the diffusion coefficient is estimated directly, i.e. without making it an adjustable parameter. The novelty of the proposed method is in its simplicity as well as its ability to isolate portions of the pressure-decay data affected by experimental fluctuations. The effect of the initial pressure on the predicted diffusion coefficient and pressure-decay profile was also investigated. The diffusion coefficients of CO2, CH4, C2H6 and N2 in Athabasca bitumen at 50–90 °C and about 8 MPa were estimated and compared with literature values. 相似文献
55.
地下水运动数值模拟过程中边界条件问题探讨 总被引:41,自引:1,他引:40
本文对地下水运动数值模拟过程中边界条件的涵义 和处理方法进行了分析和讨论。阐述了边界条件所包含的双重意义。指出随着人类活动影响 强度的日益增大,边界条件的处理要面临一些新的更为复杂的问题。在模型预报之前必须首 先对边界条件做出预报。边界条件的预报既要考虑自然因素的作用,同时也要考虑人类活动 (人工开采和人工补给)的影响及由于邻区水流条件变化而产生的耦合效应。之后,给出了两 个应用实例。 相似文献
56.
The main purpose of the study reported here was to investigate the relative importance of complexity of syllable structure and task differences in measuring phonological awareness in low-literacy adults. This study is a replication of a study with children conducted by S. A. Stahl and B. A. Murray (1994). Results indicated that the complexity of syllable structure did indeed better describe the construct of phonological awareness in low-literacy adults. At the same time, the authors also found some differences in the pattern of literacy acquisition for their Spanish adults in comparison with child literacy acquisition in English. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
57.
We present a fictitious domain decomposition method for the fast solution of acoustic scattering problems characterized by a partially axisymmetric sound‐hard scatterer. We apply this method to the solution of a mock‐up submarine problem, and highlight its computational advantages and intrinsic parallelism. A key component of our method is an original idea for addressing a Neumann boundary condition in the general framework of a fictitious domain method. This idea is applicable to many other linear partial differential equations besides the Helmholtz equation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
58.
����������������ǰ�� 总被引:2,自引:0,他引:2
本文分析了四川盆地川西地区中三叠统雷口坡组油气成藏的地质条件,进而评价和预测了雷三段的有利勘探地区和构造。 相似文献
59.
连续双向联想记忆模型的稳定性分析 总被引:6,自引:0,他引:6
对于连续型Hopfield模型的平衡态特征,目前人们已经得到了很多富有意义的成果,本文说明,连续Hopfield模型的大部分结论都可以推广到连续双向联想记忆模型,我们重点讨论了平衡态条件、渐近稳定性以及围绕一稳定平衡点的吸引域等问题,所得到的结论对于BAM的设计和应用都是很有意义的。 相似文献
60.