全文获取类型
收费全文 | 17803篇 |
免费 | 3246篇 |
国内免费 | 2228篇 |
专业分类
化学 | 12823篇 |
晶体学 | 245篇 |
力学 | 1114篇 |
综合类 | 156篇 |
数学 | 1841篇 |
物理学 | 7098篇 |
出版年
2024年 | 76篇 |
2023年 | 390篇 |
2022年 | 760篇 |
2021年 | 724篇 |
2020年 | 826篇 |
2019年 | 865篇 |
2018年 | 730篇 |
2017年 | 682篇 |
2016年 | 946篇 |
2015年 | 1000篇 |
2014年 | 1126篇 |
2013年 | 1388篇 |
2012年 | 1680篇 |
2011年 | 1625篇 |
2010年 | 1085篇 |
2009年 | 1165篇 |
2008年 | 1260篇 |
2007年 | 1037篇 |
2006年 | 975篇 |
2005年 | 808篇 |
2004年 | 619篇 |
2003年 | 466篇 |
2002年 | 442篇 |
2001年 | 363篇 |
2000年 | 293篇 |
1999年 | 282篇 |
1998年 | 212篇 |
1997年 | 209篇 |
1996年 | 180篇 |
1995年 | 168篇 |
1994年 | 127篇 |
1993年 | 125篇 |
1992年 | 102篇 |
1991年 | 91篇 |
1990年 | 68篇 |
1989年 | 43篇 |
1988年 | 43篇 |
1987年 | 43篇 |
1986年 | 37篇 |
1985年 | 36篇 |
1984年 | 22篇 |
1983年 | 30篇 |
1982年 | 15篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1975年 | 9篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Guilin Wen Qing-Guo Wang Chong Lin Xu Han Guangyao Li 《Chaos, solitons, and fractals》2006,29(5):1142-1146
Synchronization under output feedback control with multiple random time delays is studied, using the paradigm in nonlinear physics—Chua’s circuit. Compared with other synchronization control methods, output feedback control with multiple random delay is superior for a realistic synchronization application to secure communications. Sufficient condition for global stability of delay-dependent synchronization is established based on the LMI technique. Numerical simulations fully support the analytical approach, in spite of the random delays. 相似文献
52.
A simple and rapid method is developed to determine the high acidity and the basicity of solutions by chronopotentiometry with a platinum working electrode. The acidity range from 5.0 mol/l H+ to 1.0 mol/l OH− can be measured by the adjustment of deposition potential and time. The response mechanism to acidity and basicity has been explored. The transition potential plateau in chronopotentiograms is caused from the oxidation of hydrogen adsorbed on electrode surface. 相似文献
53.
Measurement of small-signal and large-signal responses of packaged laser modules at high temperature
Ning Hua Zhu Ji Min Wen Hai Peng Song Shang Jian Zhang Liang Xie 《Optical and Quantum Electronics》2006,38(15):1245-1257
In this paper, the pulsed injection method is extended to measure the chip temperature of various packaged laser modules,
such as the DFB laser modules, the FP laser modules, and the EML laser modules. An optimal injection condition is obtained
by investigating the dependence of the lasing wavelength on the width and period of the injection pulse in a relatively wide
temperature range. The small-signal frequency responses and large-signal performances of packaged laser modules at different
chip temperature are measured. The adiabatic small-signal modulation characteristics of packaged LD are first extracted. In
the large-signal measurement, the effects of chip temperature, bias current and driving signal on the performances of the
laser modules are discussed. It has been found that the large-signal performances of the EML modules depend on the different
red-shift speeds of the DFB and EAM sections as chip temperature varying, and the optimal characteristics may be achieved
at higher temperature. 相似文献
54.
Peng Xu Haitao Wang Rui Lv Qiangguo Du Wei Zhong Yuliang Yang 《Journal of polymer science. Part A, Polymer chemistry》2006,44(12):3911-3920
A novel microphase‐inversion method was proposed for the preparation of TiO2–SiO2/poly(methyl methacrylate) core–shell nanocomposite particles. The inorganic–polymer nanocomposites were first synthesized via a free‐radical copolymerization in a tetrahydrofuran solution, and the poor solvent was added slowly to induce the microphase separation of the nanocomposite and result in the formation of nanoparticles. The average particle sizes of the microspheres ranged from 70 to 1000 nm, depending on the reaction conditions. Transmission electron microscopy and scanning electron microscopy indicated a core–shell morphology for the obtained microspheres. Thermogravimetric analysis and X‐ray photoelectron spectroscopy measurements confirmed that the surface of the nanocomposite microspheres was polymer‐rich, and this was consistent with the core–shell morphology. The influence of the synthetic conditions, such as the inorganic composition and the content of the crosslinking monomer, on the particle properties was studied in detail. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3911–3920, 2006 相似文献
55.
Peng Chen Jun Chen Baoqing Zhang Jun Zhang Jiasong He 《Journal of Polymer Science.Polymer Physics》2006,44(6):1020-1030
Polycarbonate (PC) was melt blended with small amount of liquid‐crystalline polymer (LCP) and various contents of glass beads (GB) having different diameters. The rheological measurements indicated that the GB addition increased the viscosity ratio and seemed unfavorable to the LCP fibrillation. However, the morphological observation showed that the LCP fibrillation was promoted by the GB addition and varied with the GB packing. With the increased GB packing by increasing the GB content and/or decreasing the GB diameter, LCP deformed from spheres and ellipsoids into stretched ellipsoids at lower shear rates and into long fibrils at higher shear rates. Although higher content of smaller GB jammed into the larger LCP droplets and inhibited the LCP fibrillation, very long LCP fibrils formed at higher shear rates at a high enough packing of GB. The relationship between GB packing and LCP fibrillation revealed two kinds of hydrodynamic effects of GB promoting the LCP fibrillation: at lower GB packing, the shear flow was enhanced by the high local shear between GB, in quantity; and for a high enough GB packing, the shear flow was changed, in quality, into elongational flow, which was more effective for the LCP fibrillation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1020–1030, 2006 相似文献
56.
57.
58.
59.
60.
In this paper we investigate the effects of gravitational waves (GW) on a superconducting cylindrical antenna (S-antenna). We suggest that the electric fields induced by GW of dimensionless amplitudeh - 10–24 in the interior of existing cylindrical antenna might be detectable. 相似文献