全文获取类型
收费全文 | 48729篇 |
免费 | 6864篇 |
国内免费 | 5371篇 |
专业分类
化学 | 34856篇 |
晶体学 | 607篇 |
力学 | 2639篇 |
综合类 | 412篇 |
数学 | 5548篇 |
物理学 | 16902篇 |
出版年
2024年 | 147篇 |
2023年 | 886篇 |
2022年 | 1426篇 |
2021年 | 1566篇 |
2020年 | 1699篇 |
2019年 | 1655篇 |
2018年 | 1416篇 |
2017年 | 1359篇 |
2016年 | 2064篇 |
2015年 | 2086篇 |
2014年 | 2455篇 |
2013年 | 3327篇 |
2012年 | 4052篇 |
2011年 | 4304篇 |
2010年 | 2955篇 |
2009年 | 2803篇 |
2008年 | 3170篇 |
2007年 | 2978篇 |
2006年 | 2656篇 |
2005年 | 2331篇 |
2004年 | 1781篇 |
2003年 | 1490篇 |
2002年 | 1421篇 |
2001年 | 1154篇 |
2000年 | 1021篇 |
1999年 | 1034篇 |
1998年 | 844篇 |
1997年 | 798篇 |
1996年 | 772篇 |
1995年 | 677篇 |
1994年 | 664篇 |
1993年 | 581篇 |
1992年 | 511篇 |
1991年 | 466篇 |
1990年 | 404篇 |
1989年 | 301篇 |
1988年 | 252篇 |
1987年 | 216篇 |
1986年 | 195篇 |
1985年 | 198篇 |
1984年 | 143篇 |
1983年 | 88篇 |
1982年 | 95篇 |
1981年 | 70篇 |
1980年 | 66篇 |
1979年 | 58篇 |
1978年 | 40篇 |
1976年 | 37篇 |
1974年 | 40篇 |
1973年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Zhao Zheng Zhang Jian-hua Jiang Ya-ling 《International Journal of Theoretical Physics》1997,36(6):1359-1368
The Hawking effect of a nonuniformly rectilinearly accelerating Kinnersley black hole is studied. Its horizons are rotationally
symmetric. Its Hawking temperature depends not only on the time, but also on the polar angle. When a Kinnersley black hole
touches its Rindler horizon, the Hawking temperature at the contact point is reduced to zero. But at the opposite pole of
the black hole, the Hawking temperature increases rapidly. A jet appears as a tail of the accelerating black hole. 相似文献
32.
报道了KDP晶体中的三倍频产生的实验研究,计算了比较了直接三倍频过程和级联过程对KDP晶体三阶有效非线性系数的贡献,并探讨了KDP作为非线性晶体材料三阶非线性系数测量基准的可行性。 相似文献
33.
Song Jiang 《Mathematische Nachrichten》1998,190(1):169-183
We consider initial boundary value problems for the equations of the one-dimensional motion of a viscous, heat-conducting gas with density-dependent viscosity that decreases (to zero) with decreasing density. We prove that if the viscosity does not decrease to zero too rapidly, then smooth solutions exist globally in time. 相似文献
34.
本文证明了周期单元中带有某些硬相互作用的相对论Boltzmann方程初值问题在初值满足质量、能量和熵有限的条件下具有一个整体温和解. 相似文献
35.
36.
37.
The structural stability of heat-treated CoN/CN soft X-ray multilayers fabricated by dual-facing-target sputtering has been investigated by using complementary measurement techniques. The high temperature annealing results imply that the destructive threshold of the Co/C multilayers is improved by 100–200 degrees centigrade through doping with N. The low-angle X-ray diffraction of CoN/CN soft X-ray multilayers indicates that the period expansion of the multilayers is only 4 % at 400°C, and the interface pattern still exists even if they were annealed at 700°C. The Raman spectra analyses give the evidence that the formation of the sp3 bonding in the CN sublayers can be suppressed effectively by doping N with atoms, and thus the period expansion resulting from the changes in the density of CN layers can be decreased considerably. The X-ray photoelectron spectra analyses present the information of the existence of the strong covalent bonding betweenC andN atoms, and the ionic bonding between Co and N atoms, which can slow down the tendency of the structural relaxation. The interstitial N atoms decrease the mobility of Co atoms, and thus the fcc-Co and hcp-Co coexist even though the annealing temperature is much higher than the phase transformation temperature of 420°C, leading to the suppression of the grain growth. 相似文献
38.
采用固源Si分子束外延,在较高的生长温度于Si(100)衬底上制备出Si1-xGex/Si量子阱发光材料。发光样品的质量和特性通过卢瑟福背散射、X射线双晶衍射及光致发光评估。背散射实验中观察到应变超晶格的反常沟道效应;X射线分析表明材料的生长是共度的、无应力释放的,结晶完整性好。低温光致发光主要是外延合金量子阱中带边激子的无声发射和横光学声子参与的激子复合。并讨论了生长温度对量于阱发光的影响。 相似文献
39.
40.
Chii-Wann Lin Kuo-Ping Chen Ming-Chii Su Chih-Kung Lee Chih-Chung Yang 《Optical and Quantum Electronics》2005,37(13-15):1423-1437
We have reported a novel design of surface plasmon resonance (SPR) device, which uses alternating dielectric layers to enhance the SPR signal quality and modulate its resonant position. Admittance loci method of thin film design has been used in the design of such a device. The use of biomolecular thin film, such as DNAs or Porteins, in this design can result in resonant condition of wavelength changes as well. Bio-plasmonics is proposed for the research and development of novel devices, which use biomolecules as a part of the plasmon oscillation system to actively interact with nano/micro structure. 相似文献