全文获取类型
收费全文 | 50644篇 |
免费 | 8482篇 |
国内免费 | 5492篇 |
专业分类
化学 | 35356篇 |
晶体学 | 682篇 |
力学 | 3165篇 |
综合类 | 352篇 |
数学 | 6138篇 |
物理学 | 18925篇 |
出版年
2024年 | 120篇 |
2023年 | 1019篇 |
2022年 | 1340篇 |
2021年 | 1671篇 |
2020年 | 2041篇 |
2019年 | 1900篇 |
2018年 | 1683篇 |
2017年 | 1534篇 |
2016年 | 2353篇 |
2015年 | 2337篇 |
2014年 | 2745篇 |
2013年 | 3624篇 |
2012年 | 4351篇 |
2011年 | 4549篇 |
2010年 | 3081篇 |
2009年 | 3052篇 |
2008年 | 3388篇 |
2007年 | 3001篇 |
2006年 | 2829篇 |
2005年 | 2308篇 |
2004年 | 1809篇 |
2003年 | 1512篇 |
2002年 | 1430篇 |
2001年 | 1141篇 |
2000年 | 1145篇 |
1999年 | 1095篇 |
1998年 | 914篇 |
1997年 | 827篇 |
1996年 | 868篇 |
1995年 | 773篇 |
1994年 | 667篇 |
1993年 | 549篇 |
1992年 | 519篇 |
1991年 | 414篇 |
1990年 | 387篇 |
1989年 | 303篇 |
1988年 | 264篇 |
1987年 | 220篇 |
1986年 | 189篇 |
1985年 | 191篇 |
1984年 | 139篇 |
1983年 | 87篇 |
1982年 | 74篇 |
1981年 | 56篇 |
1980年 | 27篇 |
1979年 | 18篇 |
1976年 | 10篇 |
1975年 | 11篇 |
1971年 | 8篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
963.
964.
965.
Bai JZ Bardon O Blum I Breakstone A Burnett T Chen GP Chen HF Chen J Chen SJ Chen SM Chen Y Chen YB Chen YQ Cheng BS Cowan RF Cui HC Cui XZ Ding HL Du ZZ Dunwoodie W Fan XL Fang J Fero M Gao CS Gao ML Gao SQ Gao WX Gratton P Gu JH Gu SD Gu WX Gu YF Guo YN Han SW Han Y Harris FA Hatanaka M He J He KR He M Hitlin DG Hu GY Hu HB Hu T Hu XQ Huang DQ Huang YZ Izen JM Jia QP Jiang CH Jin Y Jones L Kang SH Kelsey MH Kim BK Lai YF Lan HB Lang PF Lankford A Li F Li J Li PQ Li Q Li RB 《Physical review D: Particles and fields》1995,52(7):3781-3784
966.
高亮度高效率蓝色聚合物发光二极管 总被引:7,自引:2,他引:5
蓝色聚合物发光二极管是人们关注的课题,前不久,我们报道[1]了利用ITO/PVCz/BBOT/Mg·Ag结构达到亮度1700cd/m2,量子效率0.2%的蓝色器件.在本文中我们报道以掺杂perylene(PRL)和triphenylamine(TPA)的poly(N-vinylcar-bazole)(PVCz)为空穴传输层,以PBD为空穴锁住层,Alq为电子注入层的器件,其亮度达6100cd/m2,量子效率达0.7500,流明效率0.451m/W的蓝色发光器件.就我们所知,这个亮度是蓝光中最高的亮度. 相似文献
967.
Electropolymerized m-phenylenediamine was used as an active coating for immobilizing urease and lectin on a gold-plated thickness-shear-mode (TSM) crystal. To enhance effectiveness of immobilization. a bilayer polymer film composed of polyaniline and poly-m-phenylenediamine was proposed. Compared with single poly-m-phenylenediamine film, the bilayer polymer film gave better results in terms of immobilizing capacity, stability and reproductivity. On this bilayer-film-coated TSM quartz crystal, the amount of immobilized lectin was estimated about 1.8 mug/cm(2). Detection of purified human erythrocytes is demonstrated as an example of potential application of this lectin-modified TSM biosensor in clinic. 相似文献
968.
On invexity-type nonlinear programming problems 总被引:3,自引:0,他引:3
Z. K. Xu 《Journal of Optimization Theory and Applications》1994,80(1):135-148
In this paper, we propose a new class of nonlinear programing, called SFJ-invex programming. The optimality characterization shows that a problem is SFJ-invex if and only if a Fritz John point together with its multiplier, is a Fritz John saddle point of the problem. Under any constraint qualification assumption, a problem is SFJ-invex if and only if a Kuhn-Tucker point together with its multiplier is a Kuhn-Tucker saddle point of the problem. Furthermore, a generalization of the SFJ-invex, class is developed; the applications to (h, )-convex programming, particularly geometric programming, and to generalized fractional programming provide a relaxation in constraint qualification for differentiable problems to get saddle-point type optimality criteria.The author wishes to thank the referee for helpful comments. 相似文献
969.
The effects of media properties including buffers, acidity, solvents and surfactant on horseradish peroxidase-catalyzed fluorogenic reaction were investigated. The results showed that the so-called non-fluorescent hydrogen donors were in fact fluorescent. There existed an acid—base equilibrium in the fluorescent dimer product. For p -hydroxyphenylpropionic acid, a pKa value of 8.0 for the product was obtained from its titration curve. The product fluorescence increased with higher pH, however, a longer time was needed to reach the reaction equilibrium due to the pH mismatch problem. Cationic micelles cetyltrimethylammonium bromide and cetyltrimethylammonium chloride could reduce the pH mismatch and offered a way to further increase the determination sensitivity. Finally, a micelle-enhanced flow-injection analysis of horseradish peroxidase is suggested. 相似文献
970.
许树声 《应用数学学报(英文版)》1994,10(3):262-273
ALTERNATIONTHEORYINAPPROXIMATIONBYPOLYNOMIALSHAVINGBOUNDEDCOEFFICIENTSXUSHUSHENG(许树声)(JiangnanUniversity,Wuxi214063,China)Abs... 相似文献