全文获取类型
收费全文 | 11777篇 |
免费 | 3855篇 |
国内免费 | 743篇 |
专业分类
化学 | 2086篇 |
晶体学 | 173篇 |
力学 | 399篇 |
综合类 | 46篇 |
数学 | 68篇 |
物理学 | 13603篇 |
出版年
2024年 | 22篇 |
2023年 | 57篇 |
2022年 | 177篇 |
2021年 | 231篇 |
2020年 | 218篇 |
2019年 | 160篇 |
2018年 | 229篇 |
2017年 | 351篇 |
2016年 | 432篇 |
2015年 | 431篇 |
2014年 | 738篇 |
2013年 | 767篇 |
2012年 | 773篇 |
2011年 | 1077篇 |
2010年 | 695篇 |
2009年 | 775篇 |
2008年 | 882篇 |
2007年 | 1000篇 |
2006年 | 881篇 |
2005年 | 712篇 |
2004年 | 716篇 |
2003年 | 587篇 |
2002年 | 607篇 |
2001年 | 485篇 |
2000年 | 541篇 |
1999年 | 487篇 |
1998年 | 378篇 |
1997年 | 343篇 |
1996年 | 314篇 |
1995年 | 234篇 |
1994年 | 198篇 |
1993年 | 162篇 |
1992年 | 163篇 |
1991年 | 126篇 |
1990年 | 101篇 |
1989年 | 77篇 |
1988年 | 51篇 |
1987年 | 57篇 |
1986年 | 30篇 |
1985年 | 19篇 |
1984年 | 24篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 17篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
激光防护技术的发展现状 总被引:8,自引:1,他引:7
为了对抗日趋严重的激光致盲威胁 ,世界各国加速发展激光防护技术 ,并已取得了相当大的进展。本文综述激光防护技术的发展现状 相似文献
952.
953.
A numerical analysis was carried out to study the moving boundary problem in the physical process of pulsed Nd-YAG laser surface
melting prior to vaporization. The enthalpy method was applied to solve this two-phase axisymmetrical melting problem. Computational
results of temperature fields were obtained, which provide useful information to practical laser treatment processing. The
validity of enthalpy method in solving such problems is pressented.
Supported by the National Natural Science Foundation of China and the Chinese Academy of Sciences 相似文献
954.
Hydrodynmaic efficiency of laser-irradiated thin aluminum and gold-coated aluminum targets was experimentally determined using
a specially designed cone calorimeter. Velocity of the accelerated target and ablation pressure were also estimated from the
experimental data. The laser irradiance range used in the experiments was between 1012 and 1013 watts/cm2. Experiments indicate that the fall in the hydrodynamic efficiency due to gold coating on aluminum target is about 12% at
an irradiance of 8 × 1012 W/cm2. 相似文献
955.
用150fs的掺钛蓝宝石激光系统, 在功率密度约为5×1015 W/cm2时 激励氩(Ar)团簇,利用具有空间分辨能力的平场光栅谱仪观察到13—23nm波段Ar的软x射线谱,并观察到Ar的11阶离子谱线.在较宽的激光脉宽和较低的激光功率密度情况下,通过激励Ar团簇,获得 了Ar的高阶电离度的实验结果,且谱线的信噪比明显好于光场感应电离的情况,说明团簇的 形成大幅度地提高了激光能量的吸收效率.
关键词:
Ar团簇
超短强激光
软x射线辐射 相似文献
956.
957.
Pawel Kowalczyk Shunji Kasahara Md.Humayun Kabir Hajime Kat 《Journal of Molecular Spectroscopy》2003,220(2):162-169
The E(4) 1Πu←X 1Σ+g band system of the K2 molecule is investigated by the technique of Doppler-free optical–optical double resonance polarization spectroscopy. The observed vibrational levels v=0 to 9 of the E state are subject to numerous rotational perturbations by the neighboring 4 3Πu, 4 1Σ+u, and 5 3Σ+u electronic states. By using deperturbation methods, the potential curves of the 4 1Πu and 4 3Πu states are determined as well as some properties of the 4 1Σ+u and 5 3Σ+u state potentials. The results are compared with predictions of ab initio calculations. 相似文献
958.
Simultaneous two-dimensional imaging of an unburnt area and a reacting area was performed using laser-induced fluorescence. Acetone was added to fuel as a tracer, and OH radical was used as a marker of the reacting area. A narrow band tunable KrF excimer laser (248 nm) was employed to excite acetone and OH simultaneously. Two intensified CCD cameras with different wavelength filters were used to detect these two kinds of species respectively. Detecting 294-314 nm (A-X (3, 2), etc.) for OH and 335-410 nm for acetone, we obtained images of each species without interference of a signal from the other. The method was also successfully applied to flames in a pressurized combustion chamber under the pressure of 0.5 MPa. 相似文献
959.
960.
Koji Nonaka Hidehiko Takara Atsushi Takada Kentaro Uchiyama Yoshiaki Yamabayashi 《Optical Review》1998,5(6):331-333
An optical mono-stable multivibrator laser diode (MM-LD) is realized by using a multi-electrode distributed feedback laser diode. All-optical pulse-width conversion of ultra-short pulses to non-return-to-zero (NRZ) is achieved using an MM-LD. The MM-LD is adopted for a wide range of bit-rates between 2-10 Gbit/s by tuning the DC bias. Data format transformation from 10-Gbit/s return-to-zero optical signals to NRZ optical-signals is achieved with error free operation. Converted optical signals, which have a narrower spectral bandwidth and lower peak power than when input, are transmitted using a 1.3-μm zero dispersion fiber (1.3Aλ0-SMF). 相似文献