全文获取类型
收费全文 | 19412篇 |
免费 | 3082篇 |
国内免费 | 2162篇 |
专业分类
化学 | 13361篇 |
晶体学 | 203篇 |
力学 | 1394篇 |
综合类 | 132篇 |
数学 | 2397篇 |
物理学 | 7169篇 |
出版年
2024年 | 90篇 |
2023年 | 435篇 |
2022年 | 690篇 |
2021年 | 746篇 |
2020年 | 761篇 |
2019年 | 750篇 |
2018年 | 670篇 |
2017年 | 662篇 |
2016年 | 932篇 |
2015年 | 918篇 |
2014年 | 1032篇 |
2013年 | 1423篇 |
2012年 | 1623篇 |
2011年 | 1749篇 |
2010年 | 1190篇 |
2009年 | 1102篇 |
2008年 | 1320篇 |
2007年 | 1069篇 |
2006年 | 1052篇 |
2005年 | 774篇 |
2004年 | 676篇 |
2003年 | 527篇 |
2002年 | 539篇 |
2001年 | 408篇 |
2000年 | 392篇 |
1999年 | 444篇 |
1998年 | 361篇 |
1997年 | 302篇 |
1996年 | 307篇 |
1995年 | 269篇 |
1994年 | 220篇 |
1993年 | 218篇 |
1992年 | 177篇 |
1991年 | 154篇 |
1990年 | 152篇 |
1989年 | 118篇 |
1988年 | 85篇 |
1987年 | 70篇 |
1986年 | 55篇 |
1985年 | 53篇 |
1984年 | 38篇 |
1983年 | 28篇 |
1982年 | 27篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1957年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Shao Su Xinpan Wei Yuanyuan Guo Yiling Zhong Yuanyuan Su Qing Huang Chunhai Fan Yao He 《Particle & Particle Systems Characterization》2013,30(4):326-331
A new kind of silicon nanowire (SiNWs)‐based nanoelectrode assembly, a gold‐nanoparticle‐decorated silicon nanowire array (AuNPs@SiNWsAr), is employed for the construction of high‐performance electrochemical sensors. Significantly, the electrochemical nanosensors are capable of sensitive detection of various electroactive molecules (e.g., dopamine (DA), ascorbic acid (AA), hydrogen peroxide (H2O2), and glucose). Further, DA molecules loaded on the surface of AuNPs@SiNWsAr preserve stable high electroactivity overnight without special protection, while free DA molecules may lose their biological activity due to severe oxidization in ambient environment. These findings may offer new opportunities for the design of high‐performance electrochemical nanosensors with high sensitivity and robust stability. 相似文献
152.
153.
Joseph W. Rumer Sheng‐Yao Dai Matthew Levick Laure Biniek David J. Procter Iain McCulloch 《Journal of polymer science. Part A, Polymer chemistry》2013,51(6):1285-1291
Two novel dihydropyrroloindoledione (DPID)‐based copolymers have been synthesized in a two directional approach and characterized (gel permeation chromatography (GPC), ultraviolet‐visible (UV–vis), cyclic voltammetry, and computational models). These planar, broad absorption copolymers show promise for use in organic electronics, with deep energy levels and low bandgaps. The two‐directional Knoevenagel condensation used demonstrates the versatility of DPID as a useful yet underexploited conjugated unit. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
154.
Impacts of air pressure on the evolution of nanosecond pulse discharge products 总被引:1,自引:0,他引:1 下载免费PDF全文
Based on the nonequilibrium plasma dynamics of air discharge, a dynamic model of zero-dimensional plasma is established by combining the component density equation, the Boltzmann equation, and the energy transfer equation. The evolution properties of nanosecond pulse discharge (NPD) plasma under different air pressures are calculated. The results show that the air pressure has significant impacts on the NPD products and the peak values of particle number density for particles such as O atoms, O3 molecules, N2(A3) molecules in excited states, and NO molecules. It increases at first and then decreases with the increase of air pressure. On the other hand, the peak values of particle number density for N2(B3) and N2(C3) molecules in excited states are only slightly affected by the air pressure. 相似文献
155.
We describe a Q-switched Er:GdVO4 laser resonantly pumped by a MgO-doped periodically poled LiNbO3 optical parametric oscillator (MgO: PPLN OPO) at 1536 nm. In continuous-wave lasing, the maximum output power is 1.14 W with an incident pump power of 4.7 W and a slope efficiency of 27%. In Q-switched operation, 1.1 mJ of output pulse energy is achieved at 200 Hz. The upper-state lifetime at different pulse repetition frequencies is also calculated. 相似文献
156.
157.
158.
压印光刻中套刻需要粗、精两级对正.实验采用一对斜纹结构光栅作为对正标记.利用物镜组观察光栅标记图像的边界特征进行粗对正,其准确度在精对正信号的捕捉范围内;利用光电接收器件阵列组合接收光栅莫尔信号,在莫尔信号的线区进行精对正.由于线性区的斜率大, 精对正过程中得到相应x,y方向的对正误差信号灵敏度高,利用高灵敏度对正误差信号作为控制系统的驱动信号,对承片台进行驱动定位,实现精对正.最终使X,Y方向上的重复对正准确度分别达到了± 21 nm(± 3σ)和±24 nm(± 3σ). 相似文献
159.
基于多组态Dirac-Fock理论方法,利用GRASP92和RATIP以及在此基础上最新发展的RERR06程序,对类氢U91+(1s)离子的辐射复合截面以及辐射退激发过程进行了详细的理论研究.系统地计算了具有确定能量的连续电子被处于基态的类氢U91+(1s)离子俘获到nl (1≤n≤8, 0≤l≤6)轨道形成类氦U90+(1snl)离子的辐射复合截面,并研究了这辐射复合末态退激发谱的相对强度.研究发现,类氢U91+(1s)离子辐射复合到不同轨道的截面随其主量子数的增大而显著减小;同时,辐射复合末态的退激发对Kα谱线的相对强度有重要影响.
关键词:
辐射复合
多组态Dirac-Fock理论方法
辐射退激发 相似文献
160.
Monodisperse Au-Fe 3 O 4 heterodimeric nanoparticles (NPs) were prepared by injecting precursors into a hot reaction solution.The size of Au and Fe 3 O 4 particles can be controlled by changing the injection temperature.UV-Vis spectra show that the surface plasma resonance band of Au-Fe 3 O 4 heterodimeric NPs was evidently red-shifted compared with the resonance band of Au NPs of similar size.The as-prepared heterodimeric Au-Fe 3 O 4 NPs exhibited superparamagnetic properties at room temperature.The Ag-Fe 3 O 4 heterodimeric NPs were also prepared by this synthetic method simply using AgNO 3 as precursor instead of HAuCl 4.It is indicated that the reported method can be readily extended to the synthesis of other noble metal conjugated heterodimeric NPs. 相似文献