全文获取类型
收费全文 | 8655篇 |
免费 | 526篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 122篇 |
综合类 | 23篇 |
化学工业 | 2251篇 |
金属工艺 | 243篇 |
机械仪表 | 156篇 |
建筑科学 | 593篇 |
矿业工程 | 104篇 |
能源动力 | 286篇 |
轻工业 | 623篇 |
水利工程 | 51篇 |
石油天然气 | 20篇 |
武器工业 | 1篇 |
无线电 | 688篇 |
一般工业技术 | 1828篇 |
冶金工业 | 509篇 |
原子能技术 | 58篇 |
自动化技术 | 1633篇 |
出版年
2024年 | 15篇 |
2023年 | 118篇 |
2022年 | 210篇 |
2021年 | 334篇 |
2020年 | 202篇 |
2019年 | 214篇 |
2018年 | 233篇 |
2017年 | 271篇 |
2016年 | 356篇 |
2015年 | 296篇 |
2014年 | 380篇 |
2013年 | 605篇 |
2012年 | 542篇 |
2011年 | 731篇 |
2010年 | 514篇 |
2009年 | 484篇 |
2008年 | 500篇 |
2007年 | 440篇 |
2006年 | 393篇 |
2005年 | 317篇 |
2004年 | 273篇 |
2003年 | 197篇 |
2002年 | 174篇 |
2001年 | 106篇 |
2000年 | 101篇 |
1999年 | 125篇 |
1998年 | 144篇 |
1997年 | 101篇 |
1996年 | 96篇 |
1995年 | 56篇 |
1994年 | 68篇 |
1993年 | 41篇 |
1992年 | 48篇 |
1991年 | 27篇 |
1990年 | 42篇 |
1989年 | 25篇 |
1988年 | 32篇 |
1987年 | 29篇 |
1986年 | 26篇 |
1985年 | 29篇 |
1984年 | 32篇 |
1983年 | 24篇 |
1982年 | 21篇 |
1981年 | 17篇 |
1980年 | 23篇 |
1978年 | 17篇 |
1977年 | 20篇 |
1976年 | 34篇 |
1975年 | 17篇 |
1969年 | 12篇 |
排序方式: 共有9189条查询结果,搜索用时 15 毫秒
881.
In 3 studies, the authors demonstrated that individuals are motivated by role models who encourage strategies that fit their regulatory concerns: Promotion-focused individuals, who favor a strategy of pursuing desirable outcomes, are most inspired by positive role models, who highlight strategies for achieving success; prevention-focused individuals, who favor a strategy of avoiding undesirable outcomes, are most motivated by negative role models, who highlight strategies for avoiding failure. In Studies 1 and 2, the authors primed promotion and prevention goals and then examined the impact of role models on motivation. Participants' academic motivation was increased by goal-congruent role models but decreased by goal-incongruent role models. In Study 3, participants were more likely to generate real-life role models that matched their chronic goals. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
882.
883.
Jacek Slowik Günter Borchardt Christian Khler Rudolf Jeschar Reinhard Scholz 《国际钢铁研究》1990,61(7):302-311
In order to model heat transfer from the slab to the cooling agent in the continuous casting process the thermophysical properties of the surface layer must be taken into account. For this purpose thermal conductivities and thermal diffusivities of wustite as well as of two carbon steels were measured. The oxide scale growth for six steels was measured as a function of time and at temperatures between 900 and 1200°C in air and in steam. Complex heterogeneous oxide scales were examined by optical and scanning electron microscopy, by SIMS, as well as by Mössbauer spectroscopy. Segregation of alloying elements in the metal-oxide contact zone was found. Cracks due to thermal stresses result in spalling of the scale. Therefore, a straightforward use of the data for process modelling can principally not be recommended without restrictions. 相似文献
884.
Local economic development in Midrand, South Africa’s ecocity 总被引:1,自引:1,他引:0
Christian M. Rogerson 《Urban Forum》2003,14(2-3):201-222
885.
886.
Christian Cilas Pierre Bouharmont 《Journal of the science of food and agriculture》2005,85(14):2369-2374
The genetic parameters of several bean traits of coffee from the species Coffea canephora were estimated using two mating designs: a triangular diallel with 6 parents and a partial diallel with 18 parents. The traits studied were: normal bean weight, the percentage of peaberries, the length, width and thickness of the beans. These characteristics were studied along with yield. The yield data came from harvests obtained over 14 years divided into an initial cycle of 6 years, a second cycle of 5 years after cutting back and a third cycle of 3 years after topping. The general combining abilities (GCA) were the principal sources of significant variation for the traits studied. Transmission of these traits was therefore mostly additive. Yield over 14 years was the most heritable trait. The rank correlations between the GCA of the bean traits and those of yield were not significant. The genetic correlations estimated in the partial diallel did not reveal any link between bean traits and yield. Only one genetic correlation between the peaberry rate and yield was significant. The peaberry rate was linked to fertility, which thus appeared to be a genetic component of yield. Index‐based selection combining an increase in yield with improved bean traits could therefore be carried out without any particular difficulty. Copyright © 2005 Society of Chemical Industry 相似文献
887.
888.
889.
Christian Rosenkilde Liv Hilde Arnesen Oddmund Wallevik 《Journal of Phase Equilibria and Diffusion》2004,25(3):255-258
The solubilities of chloride (Cl) in liquid magnesium (Mg) have been determined from the analysis of quenched samples of liquid
Mg equilibrated with NaCl-MgCl2 melts of different compositions at temperatures in the range 650–790 °C. As an example, the solubility of Cl in liquid Mg
in contact with pure MgCl2 at 735 °C was found to be approximately 18 ppm. The Cl solubility was found to be proportional to the square root of the
MgCl2 activity in the NaCl-MgCl2 melt, indicating that MgCl2 dissolved according to the reaction 0.5MgCl2 + 0.5Mg(l) = MgCl (in Mg). The temperature dependency of the solubility also was measured. Thermodynamic values related to
the dissolution of MgCl2 in liquid Mg have been estimated. 相似文献
890.
Wahlen bringen den Willen des Volkes zum Ausdruck und stellen damit einen fundamentalen Baustein für jede Demokratie dar.
Forderungen nach einer schnelleren Ausz?hlung haben dazu geführt, dass vermehrt Wahlmaschinen Einsatz finden, trotz der massiven
Kritik, die von verschiedenen Seiten ge?u?ert wird. Der Beitrag stellt ein kryptographisches Verfahren vor, das Wahlen mit
Wahlmaschinen erlaubt, ohne dabei an Transparenz und Nachvollziehbarkeit einzuben. Das Verfahren wurde mit dem Deutschen IT-Sicherheitspreis
2008 ausgezeichnet. 相似文献