全文获取类型
收费全文 | 10498篇 |
免费 | 1915篇 |
国内免费 | 1278篇 |
专业分类
化学 | 7753篇 |
晶体学 | 65篇 |
力学 | 652篇 |
综合类 | 80篇 |
数学 | 1113篇 |
物理学 | 4028篇 |
出版年
2024年 | 26篇 |
2023年 | 275篇 |
2022年 | 322篇 |
2021年 | 401篇 |
2020年 | 482篇 |
2019年 | 418篇 |
2018年 | 338篇 |
2017年 | 294篇 |
2016年 | 495篇 |
2015年 | 444篇 |
2014年 | 538篇 |
2013年 | 768篇 |
2012年 | 969篇 |
2011年 | 982篇 |
2010年 | 646篇 |
2009年 | 639篇 |
2008年 | 715篇 |
2007年 | 631篇 |
2006年 | 560篇 |
2005年 | 489篇 |
2004年 | 367篇 |
2003年 | 326篇 |
2002年 | 276篇 |
2001年 | 216篇 |
2000年 | 218篇 |
1999年 | 262篇 |
1998年 | 216篇 |
1997年 | 192篇 |
1996年 | 212篇 |
1995年 | 179篇 |
1994年 | 146篇 |
1993年 | 124篇 |
1992年 | 102篇 |
1991年 | 75篇 |
1990年 | 86篇 |
1989年 | 58篇 |
1988年 | 49篇 |
1987年 | 44篇 |
1986年 | 31篇 |
1985年 | 28篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
991.
Ling‐Hai Xie Xian‐Yu Deng Lin Chen Shu‐Fen Chen Ran‐Ran Liu Xiao‐Ya Hou King‐Young Wong Qi‐Dan Ling Wei Huang 《Journal of polymer science. Part A, Polymer chemistry》2009,47(20):5221-5229
The combination of π‐stacked with π‐conjugated building blocks offers an essential strategy to construct multifunctional organic semiconductors (MOSs) with the unique optoelectrical properties. Covalent hybrids can efficiently avoid the intrinsic phase‐separation defects in corresponding blend system. In this contribution, poly(vinylcarbazole) tethered with terfluorene, PVK‐TF, as a double‐channeled π‐stacked and π‐conjugated hybrid (SCH), has been constructed via Friedal‐Crafts click postmodification (FCCP). The chemical structure and optoelectrical property were determined by GPC, UV–vis, PL, TGA, DSC, and CV. Its PL spectra in the annealing thin film at N2 atmosphere without low‐energy emission bands centered at the 530 nm indicates that no π‐stacks between carbazole and TF or among TFs dominate the whole condensed phase, which is in agreement with the intrachain T‐shaped π‐pitched motifs in molecular modeling simulation due to steric hindrance effect in complicated diarylfluorenes (CDAFs). A supporting prototype stable deep‐blue PLED was successfully obtained with an Internationale de l'Eclairage (CIE) coordinates of (0.20, 0.10) and a width at half maximum (FWHM) of about 60 nm at high current density of 100 mA/cm2 (35 V). Deep‐blue PVK‐TF is a promising MOS for hole‐transporting and host materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5221–5229, 2009 相似文献
992.
This paper is concerned with the stability of a preemptive priority queueing system with customer transfers. Conditions for the queueing system to be stable/unstable are found. An interesting result is that the stability/instability conditions are independent of the service rates of lower priority customers and the transfer rates. 相似文献
993.
994.
995.
H. Luo D.Y. Tang G.Q. Xie H.J. Zhang L.J. Qin H.H. Yu L.Y. Ng L.J. Qian 《Optics Communications》2008,281(21):5382-5384
Passive mode-locking of a diode pumped Yb-doped GdVO4 crystal laser was demonstrated for the first time to our knowledge. The laser was mode-locked at the wavelength of 1019.1 nm and had an average output power of 1.01 W. The mode-locked pulse duration was 3.1 ps. The laser was end-pumped by a high-power fiber pigtailed laser diode bar and the mode-locking was enabled by a semiconductor saturable absorber mirror (SESAM). 相似文献
996.
997.
998.
Bin Xie 《Journal of Mathematical Analysis and Applications》2008,344(1):204-216
The pathwise uniqueness of stochastic evolution equations driven by Q-Wiener processes is mainly investigated in this article. We focus on the case that the modulus of the continuity of the coefficients is not controlled by a linear function. Additionally, we show that the corresponding diffusion process is Feller. 相似文献
999.
1000.
Dobrila Petrovic Ying Xie Keith Burnham Radivoj Petrovic 《European Journal of Operational Research》2008
This paper considers a single product inventory control in a Distribution Supply Chain (DSC). The DSC operates in the presence of uncertainty in customer demands. The demands are described by imprecise linguistic expressions that are modelled by discrete fuzzy sets. Inventories at each facility within the DSC are replenished by applying periodic review policies with optimal order up-to-quantities. Fuzzy customer demands imply fuzziness in inventory positions at the end of review intervals and in incurred relevant costs per unit time interval. The determination of the minimum of defuzzified total cost of the DSC is a complex problem which is solved by applying decomposition; the original problem is decomposed into a number of simpler independent optimisation subproblems, where each retailer and the warehouse determine their optimum periodic reviews and order up-to-quantities. An iterative coordination mechanism is proposed for changing the review periods and order up-to-quantities for each retailer and the warehouse in such a way that all parties within the DSC are satisfied with respect to total incurred costs per unit time interval. Coordination is performed by introducing fuzzy constraints on review periods and fuzzy tolerances on retailers and warehouse costs in local optimisation subproblems. 相似文献