全文获取类型
收费全文 | 4460篇 |
免费 | 113篇 |
国内免费 | 20篇 |
专业分类
化学 | 2846篇 |
晶体学 | 46篇 |
力学 | 79篇 |
数学 | 853篇 |
物理学 | 769篇 |
出版年
2023年 | 54篇 |
2022年 | 102篇 |
2021年 | 147篇 |
2020年 | 113篇 |
2019年 | 122篇 |
2018年 | 133篇 |
2017年 | 111篇 |
2016年 | 151篇 |
2015年 | 121篇 |
2014年 | 125篇 |
2013年 | 272篇 |
2012年 | 237篇 |
2011年 | 303篇 |
2010年 | 193篇 |
2009年 | 195篇 |
2008年 | 241篇 |
2007年 | 227篇 |
2006年 | 223篇 |
2005年 | 212篇 |
2004年 | 174篇 |
2003年 | 138篇 |
2002年 | 114篇 |
2001年 | 72篇 |
2000年 | 55篇 |
1999年 | 39篇 |
1998年 | 39篇 |
1997年 | 36篇 |
1996年 | 27篇 |
1995年 | 24篇 |
1994年 | 25篇 |
1993年 | 35篇 |
1992年 | 18篇 |
1991年 | 31篇 |
1990年 | 18篇 |
1989年 | 14篇 |
1987年 | 15篇 |
1986年 | 21篇 |
1985年 | 23篇 |
1984年 | 33篇 |
1983年 | 21篇 |
1982年 | 21篇 |
1981年 | 27篇 |
1980年 | 23篇 |
1979年 | 26篇 |
1978年 | 27篇 |
1977年 | 29篇 |
1975年 | 21篇 |
1974年 | 17篇 |
1958年 | 13篇 |
1955年 | 15篇 |
排序方式: 共有4593条查询结果,搜索用时 15 毫秒
81.
Nikolov I Gaydardzhiev A Buchvarov I Tzankov P Noack F Petrov V 《Optics letters》2007,32(22):3342-3344
Ultrabroadband parametric amplification of a white-light continuum in the near IR (approximately 100 THz, 1.2-2.4 microm) is demonstrated in BiB3O6 pumped by 45 fs long pulses at 800 nm at a repetition rate of 1 kHz. The energy obtained with a 5 mm thick crystal reached 50 microJ, corresponding to external conversion efficiency of 20%. 相似文献
82.
Karlsson Erik Neuhausen Jörg Eichler Robert Danilov Ivan I. Vögele Alexander Türler Andreas 《Journal of Radioanalytical and Nuclear Chemistry》2021,328(2):707-715
Journal of Radioanalytical and Nuclear Chemistry - The usage of silver as a filtering material for removal of iodine from the gas phase of a lead–bismuth eutectic based nuclear reactor was... 相似文献
83.
84.
Nataliia Yu. Strutynska Marina A. Bondarenko Ivan V. Ogorodnyk Igor V. Zatovsky Nikolay S. Slobodyanik Vyacheslav N. Baumer Anna N. Puzan 《Crystal Research and Technology》2015,50(7):549-555
The interaction in the molten system Rb2O‐P2O5‐TiO2‐NiO was investigated at different molar ratios Rb/P = 0.5‐1.3, fixed Ti/P = 0.15, Ti/Ni = 1.0 at temperature range 1073–953 K. The conditions of formation of complex phosphates RbTi2(PO4)3, Rb2Ni0.5Ti1.5(PO4)3 and RbNiPO4 have been determined. The new phosphate Rb2Ni0.5Ti1.5(PO4)3 (space group P213, a = 9.9386(2) Å) has been obtained and investigated by the single crystal X‐ray diffraction and FTIR‐spectroscopy. It has langbeinite‐like structure, that is built up from mixed (Ni/Ti)O6‐octahedra and РО4‐tetrahedra. Rubidium atoms are located in closed cavities of 3D‐framework. 相似文献
85.
86.
Md Khairul Islam Ivan Lozada Lawag Tomislav Sostaric Edie Ulrich Danny Ulrich Terrence Dewar Lee Yong Lim Cornelia Locher 《Molecules (Basel, Switzerland)》2022,27(7)
Despite its cultural and nutritional importance for local Aboriginal people, the unusual insect honey produced by Western Australian honeypot ant (Camponotus inflatus) has to date been rarely investigated. This study reports on the honey’s physicochemical properties, its total phenolic, major sugars and 5-hydroxymethylfurfural contents, and its antioxidant activities. The honey’s color value is 467.63 mAU/63.39 mm Pfund, it has a pH of 3.85, and its electric conductivity is 449.71 µSiemens/cm. Its Brix value is 67.00, corresponding to a 33% moisture content. The total phenolics content is 19.62 mg gallic acid equivalent/100 g honey. Its antioxidant activity measured using the DPPH* (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing–antioxidant power) assays is 1367.67 µmol Trolox/kg and 3.52 mmol Fe+2/kg honey, respectively. Major sugars in the honey are glucose and fructose, with a fructose-to-glucose ratio of 0.85. Additionally, unidentified sugar was found in minor quantities. 相似文献
87.
88.
Efficient and accurate integration of stochastic (partial) differential equations with multiplicative noise can be obtained through a split-step scheme, which separates the integration of the deterministic part from that of the stochastic part, the latter being performed by sampling exactly the solution of the associated Fokker-Planck equation. We demonstrate the computational power of this method by applying it to the most absorbing phase transitions for which Langevin equations have been proposed. This provides precise estimates of the associated scaling exponents, clarifying the classification of these nonequilibrium problems, and confirms or refutes some existing theories. 相似文献
89.
Vlastimil Matějec Miroslav Chomát Miloš Hayer Ivan Kašík Daniela Berková Fethi Abdelmalek Nicole Jaffrezic-Renault 《Czechoslovak Journal of Physics》1999,49(5):883-888
The paper summarizes results achieved in the Institute of Radio Engineering and Electronics in the field of investigation
and fabrication of novel fiber-optic structures for evanescent-wave chemical sensing. Several approaches for increasing the
evanescent-wave sensitivity of multimode silica optical fibers to gaseous and liquid chemicals are shown. These approaches
make use of the decrease of the core diameter in sectorial and capillary sectorial fibers, modification of trajectories of
optical rays in the cores of inverted-graded-index fibers, tailoring of the refractive index of porous layers applied on silica
cores, an output mode filter preventing the detection of rays propagating at low axial angles or fibers bent in single or
multiple turns.
Presented at the 1st Czech-Chinese Workshop “Advanced Materials for Optoelectronics”, Prague, Czech Republic, June 13–17,
1998.
This work was supported by the Grant Agency of the Czech Republic (projects No. 102/96/0939 and No. 102/98/1358) and by joint
project No. 4104 of AS CR and CNRS, France. 相似文献
90.