全文获取类型
收费全文 | 5082篇 |
免费 | 605篇 |
国内免费 | 555篇 |
专业分类
电工技术 | 284篇 |
技术理论 | 1篇 |
综合类 | 459篇 |
化学工业 | 411篇 |
金属工艺 | 94篇 |
机械仪表 | 78篇 |
建筑科学 | 512篇 |
矿业工程 | 209篇 |
能源动力 | 126篇 |
轻工业 | 342篇 |
水利工程 | 255篇 |
石油天然气 | 2382篇 |
武器工业 | 11篇 |
无线电 | 257篇 |
一般工业技术 | 321篇 |
冶金工业 | 230篇 |
原子能技术 | 39篇 |
自动化技术 | 231篇 |
出版年
2024年 | 17篇 |
2023年 | 103篇 |
2022年 | 174篇 |
2021年 | 260篇 |
2020年 | 224篇 |
2019年 | 208篇 |
2018年 | 154篇 |
2017年 | 174篇 |
2016年 | 212篇 |
2015年 | 215篇 |
2014年 | 320篇 |
2013年 | 337篇 |
2012年 | 384篇 |
2011年 | 463篇 |
2010年 | 326篇 |
2009年 | 292篇 |
2008年 | 254篇 |
2007年 | 376篇 |
2006年 | 307篇 |
2005年 | 260篇 |
2004年 | 227篇 |
2003年 | 206篇 |
2002年 | 144篇 |
2001年 | 98篇 |
2000年 | 118篇 |
1999年 | 64篇 |
1998年 | 40篇 |
1997年 | 51篇 |
1996年 | 45篇 |
1995年 | 40篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 19篇 |
1989年 | 13篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 10篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1967年 | 1篇 |
1963年 | 1篇 |
1959年 | 1篇 |
1958年 | 1篇 |
1955年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有6242条查询结果,搜索用时 15 毫秒
31.
Memory loss in retrograde amnesia has long been held to be larger for recent periods than for remote periods, a pattern usually referred to as the Ribot gradient. One explanation for this gradient is consolidation of long-term memories. Several computational models of such a process have shown how consolidation can explain characteristics of amnesia, but they have not elucidated how consolidation must be envisaged. Here findings are reviewed that shed light on how consolidation may be implemented in the brain. Moreover, consolidation is contrasted with alternative theories of the Ribot gradient. Consolidation theory, multiple trace theory, and semantization can all handle some findings well but not others. Conclusive evidence for or against consolidation thus remains to be found. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
本文介绍了运用地表岩石吸附烃法指示四川浅层油气藏,发现吸附烃异常与油气井产能有良好吻合性,反映了地下裂缝系统和油气聚集的分布。并对实验条件、各种可能的影响因素及一些基础理论问题进行了实验分析和讨论。 相似文献
33.
总结了南海北部陆缘晚期(或浅层)油气藏的勘探技术和方法,指出晚期油气成藏具有海底麻坑、气烟囱、"地震模糊带"和"亮点"等地震异常特征,从地化特征上可划分为浅层生物气、成熟—高成熟热解气和高含CO2热解气等3种油气成藏类型.在研究新构造运动表现形式的基础上,分析了逆断层、正断层和底辟—走滑断层3个断层活动区的晚期油气成藏机理,指出断层晚期活动和后期快速沉降促进了油气的运移和再分配,晚期油气成藏主要沿莺歌海盆地莺东斜坡带、东方—乐东区和沿琼东南盆地二号断裂带及珠江口盆地坳陷边缘斜坡带等分布,有利于油气和天然气水合物的勘探. 相似文献
34.
Kazutaka Chibana Chaedong Kang Masashi Okada Koji Matsumoto Tetsuo Kawagoe 《International Journal of Refrigeration》2002,25(2):83
Water-silicone oil emulsion with an additive, (C2H5O)3SiC3H6NH2, was examined as a heat storage material. A spiral tube used as a heat exchanger was immersed in a low temperature bath and the emulsion was circulated in the tube to make ice continuously. Ice was separated from the ice–liquid suspension in an outlet tank. The amount of formed ice, the temperatures of the inlet and the outlet of the heat exchanger, and the temperatures in the tube wall were measured and the overall heat transfer coefficient and the heat flux through the tube were calculated. Experiments were carried out, varying the flow rate, the temperature of cooling brine, and the thickness of tube wall. The condition under which slurry ice was formed continuously without adhesion of ice to the cooling wall was clarified. Though decrease in the thermal resistance of the tube increased the rate of ice formation or raised the brine temperature, it narrowed the range of the flow rate and of the brine temperature in which slurry ice was formed continuously. 相似文献
35.
36.
文昌A凹陷油气成藏特征与分布规律探讨 总被引:2,自引:0,他引:2
文昌A凹陷位于珠江口盆地西部,是一个发育文昌组和恩平组两套湖相烃源岩复合成藏的油气区。根据特征生物标志化合物与碳同位素组成的油岩对比结果,可将文昌A凹陷发现的原油划分为两类,即文昌Ⅱ型和恩平型,前者来自文昌组浅湖相烃源岩,后者源于恩平组湖相烃源岩;天然气主要源于恩平组烃源岩,也可能有文昌组烃源岩凝析气或裂解气的贡献。文昌A凹陷油气两期成藏,早期成油,晚期聚气及轻质油,其油气分布主要受烃源岩有机相、热演化程度和运移分馏作用等因素的控制,凹陷中部以气为主,凹陷边缘气油共存,而凸起上以油为主。 相似文献
37.
38.
乌江索风营水电站坝址区分布有7个堆积体,其成因有崩塌堆积、蠕变-拉裂-崩解堆积、塌滑堆积及混和堆积等.在勘察过程中采用了地质测绘、钻探、硐探、物探、科研试验等多种勘察方法与手段,在勘察成果基础上对堆积体稳定性进行了分析,并结合对工程的不同影响提出了相应的工程处理措施. 相似文献
39.
J. Crocker and L. E. Park (2004) have achieved an admirable integration of the self-esteem literature with their claim that self-esteem is better conceived of as a dynamic human striving, rather than as a passive state or personality characteristic. However, the costs of self-esteem striving may be overstated--these costs may arise only in certain constrained cases. Also, although Crocker and Park suggested that self-esteem is not a true psychological need, there is evidence that humans in all cultures need to feel a positive sense of self-worth (K. M. Sheldon, in press). Problems may arise only when people strive too directly for this feeling, rather than deriving it as a natural concomitant of non-self-focused goals. A "sidelong" approach to self-esteem need satisfaction is advocated in this commentary. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
40.
N. I. Bobyr’ A. P. Grabovskii A. V. Timoshenko A. P. Khalimon 《Strength of Materials》2006,38(1):92-98
Within framework of the continual fracture mechanics, we describe the engineering approach to the assessment of scattered
microdamage accumulation kinetics in metallic materials under elastoplastic loading conditions in case of plane stressed state.
Automatized experimental stand and the respective investigation technique are discussed. The stand has been developed based
on modification of the UMé-10T electromechanic test machine. State-of-the-art computer technologies and microprocessing hardware
are incorporated in the stand automation. We present the technique of experimental assessment of damage accumulation kinetics
in metallic structural materials under complex elastoplastic loading conditions with account of two different fracture (cleavage
and shear) processes, which technique is based on measuring the specific electric resistance of the specimen.
__________
Translated from Problemy Prochnosti, No. 1, pp. 128–137, January–February, 2006. 相似文献