全文获取类型
收费全文 | 85255篇 |
免费 | 996篇 |
国内免费 | 414篇 |
专业分类
电工技术 | 806篇 |
综合类 | 2317篇 |
化学工业 | 11793篇 |
金属工艺 | 4839篇 |
机械仪表 | 3043篇 |
建筑科学 | 2165篇 |
矿业工程 | 565篇 |
能源动力 | 1186篇 |
轻工业 | 3634篇 |
水利工程 | 1279篇 |
石油天然气 | 357篇 |
无线电 | 9451篇 |
一般工业技术 | 16636篇 |
冶金工业 | 2831篇 |
原子能技术 | 255篇 |
自动化技术 | 25508篇 |
出版年
2022年 | 34篇 |
2021年 | 41篇 |
2020年 | 31篇 |
2019年 | 40篇 |
2018年 | 14493篇 |
2017年 | 13405篇 |
2016年 | 9984篇 |
2015年 | 628篇 |
2014年 | 281篇 |
2013年 | 333篇 |
2012年 | 3198篇 |
2011年 | 9473篇 |
2010年 | 8326篇 |
2009年 | 5587篇 |
2008年 | 6827篇 |
2007年 | 7840篇 |
2006年 | 154篇 |
2005年 | 1255篇 |
2004年 | 1158篇 |
2003年 | 1215篇 |
2002年 | 575篇 |
2001年 | 123篇 |
2000年 | 205篇 |
1999年 | 79篇 |
1998年 | 121篇 |
1997年 | 79篇 |
1996年 | 75篇 |
1995年 | 38篇 |
1994年 | 39篇 |
1993年 | 44篇 |
1992年 | 34篇 |
1991年 | 52篇 |
1990年 | 34篇 |
1988年 | 23篇 |
1987年 | 20篇 |
1969年 | 25篇 |
1968年 | 46篇 |
1967年 | 33篇 |
1966年 | 43篇 |
1965年 | 44篇 |
1963年 | 28篇 |
1962年 | 22篇 |
1961年 | 19篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 64篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
91.
92.
Rudolf Felix 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2008,12(2):129-135
Real world applications of a decision model of relationships between goals based on fuzzy relations are presented. In contrast
to other approaches the relationships between decision goals or criteria for each decision situation are represented and calculated
explicitly. The application fields are decision making for financial services and optimization of production sequences in
car manufacturing. 相似文献
93.
94.
Wenying Wei Zhen Wang Yanhua Yin Jinyu Han Wen Xu 《Korean Journal of Chemical Engineering》2008,25(3):562-567
Composition Group Vector Space (CGVS) method for estimating melting and boiling point T
m
, T
b
of organic compound has been proposed, and the principle of this method has been elucidated. The models for estimating T
m
, T
b
have been established and the numerical values of relative parameters have been presented. The average percentage deviations
of T
m
, T
b
estimation are 7.53 and 1.58, respectively, which show that the present method demonstrates significant improvement in applicability
to predict the above properties, compared to conventional group methods. 相似文献
95.
96.
This article proposes an approach for investigating the exponential stability of a nonlinear
interval dynamical system with the nonlinearity of a quadratic type on the basis of the Lyapunov’s direct method. It also
constructs an inner estimate of the attraction domain to the origin for the system under consideration. 相似文献
97.
Summary Well-defined water-soluble poly(styrenesulfonate)-b-poly(ethylene glycol)-b- poly(styrenesulfonate) (PSS-b-PEG-b-PSS) triblock
copolymers with narrow molecular weight distribution (1.29 < Mw/Mn < 1.36) were synthesized in aqueous solution at 70 oC via reversible addition-fragmentation chain transfer (RAFT) polymerization. The complex formed by the PSS-b-PEG-b-PSS triblock
copolymer coordinated with aluminum ion was investigated with turbidimetry, dynamic light scattering (DSL), zeta-potential,
and transmission electron microscopy (TEM). The aggregation formation was based on the neutralization of the SO3- groups in the PSS blocks with Al3+ ions. The appearance, size and stability of the PSS-b-PEG-b-PSS/Al3+ aggregates were controlled by varying the PSS block length and degree of neutralization (DN). At DN = 0.33, where the PSS-b-PEG-b-PSS
copolymer was completely neutralized with Al3+, the aggregate size increased with increasing PSS block length. The transition from the shrinking coil of small size to the
interchain aggregates of large size was found at DN of about 0.33. 相似文献
98.
Modellierung in der Lehre an Hochschulen: Thesen und Erfahrungen 总被引:1,自引:1,他引:0
Martin Glinz 《Informatik-Spektrum》2008,31(5):425-434
Zusammenfassung Nicht erst seit Modellierung zum Modewort geworden ist, ist Modellierung ein wichtiges Thema in der Informatikausbildung.
Dieser Beitrag beleuchtet in zw?lf Thesen das Warum, Was, Wie viel, Wo, Wann und Wie von Modellierung in der Lehre im Rahmen
informatikbezogener Studieng?nge. Die Thesen basieren auf der Erfahrung des Verfassers mit einer seit über zehn Jahren gehaltenen
Modellierungsvorlesung an der Universit?t Zürich sowie dem Gedankenaustausch mit anderen Hochschullehrerinnen und -lehrern
im Rahmen der GI-Workshopreihe ,,Modellierung“. Zus?tzlich liefert eine Befragung von Absolventinnen und Absolventen an der
Universit?t Zürich empirische Evidenz für eine Reihe der Thesen. 相似文献
99.
This paper will describe the solid oxide membrane (SOM) process as it applies to the energy-efficient and environmentally
sound production of magnesium from magnesium oxide. Also, it will describe the challenges encountered while using this process
for the production of transition metals like titanium from its higher oxides. Finally, a novel magnesiothermic SOM process
will be proposed that can enable production of transition metals from its higher oxides. 相似文献
100.
Do Hoon Kim Umme Farva Woo Sik Jung Eui Jung Kim Chinho Park 《Korean Journal of Chemical Engineering》2008,25(5):1184-1189
This paper reports an alternative method for the growth of GaN epitaxial layer on (0001) Al2O3 substrate by hot-wall vapor phase epitaxy technique. Tris (N,N-dimethyldithiocarbamato)-gallium (III), Ga(mDTC)3 was introduced as a precursor material for the seed layer formation in the growth of GaN. Optimal growth conditions with
seed layers formed by the Ga(mDTC)3 concentration of 0.047 mol/L were identified: Growth temperature was found to be 850 °C, and optimal distance between the
reactant outlet and substrate was determined to be 12.5 cm. Characterization results showed that this growth method produce
high-crystallinity GaN epitaxial layers at a relatively lower growth temperature compared to the existing growth techniques
and simplify the growth process. 相似文献