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71.
72.
InAs/GaSb/AlSb resonant tunneling spin device concepts 总被引:1,自引:0,他引:1
David Z. -Y. Ting Xavier Cartoix 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):350
We discuss device concepts for creating spin-polarized current sources without external magnetic fields, using non-magnetic 6.1 Å semiconductor resonant tunneling structures. Spin filters, spin pumps, and spin transistors that exploit structural and bulk inversion asymmetries will be examined. 相似文献
73.
Homopolymerization of methyl methacrylate (MMA) was carried out in the presence of triphenylstibonium 1,2,3,4-tetraphenyl-cyclopentadienylide
as an initiator in dioxane at 65°C±0·l°C. The system follows non-ideal radical kinetics (R
p
∝ [M]1·4 [I]0·44
@#@) due to primary radical termination as well as degradative chain-transfer reaction. The overall activation energy and average
value ofk
2
p
/k
t
were 64 kJmol−1 and 0.173 × 10−3 1 mol−1 s−1 respectively 相似文献
74.
HCHO-(DL-苹果酸)-BrO-3-Mn2+-H2SO4体系化学振荡反应动力学研究 总被引:1,自引:0,他引:1
研究了HCHO参与下的(DL-苹果酸)-BrO-3-Mn2+-H2SO4化学振荡反应体系的非线性动力学行为,考察了该体系中各反应物的初始浓度范围及主要影响因素. 结果表明,在5.0×10-5~1.0×10-2 mol·L-1范围内, HCHO对振荡反应的诱导期和周期有较大影响,且HCHO浓度的对数lnc(HCHO)与诱导期倒数的对数ln(1/tin)及周期倒数的对数ln(1/tp)均存在线性关系. 诱导期和周期的表观活化参数分别为70.87,55.71 kJ·mol-1. 另外还对HCHO参与下的可能振荡反应机理进行了探讨. 相似文献
75.
On the basis of critical comparison of experimental and theoretical values of the E parameter and investigation of the retardation effect of oxygen on the evaporation rate of ZnO, CdO and HgO, it was concluded that the dissociative evaporation of ZnO and HgO proceeds with releasing of atomic oxygen (O) as a primary product of decomposition. By contrast, the mechanism of dissociative evaporation of CdO corresponds to the equilibrium reaction with releasing of molecular oxygen (O2) as a primary product of decomposition. As was shown, this difference in mechanisms is not related with interatomic OO distances in these oxides. From the analysis of crystal structure for 12 different oxides, which evaporate with releasing of atomic oxygen, and for 13 compounds, which evaporate with releasing of molecular oxygen, it was revealed that the first mechanism is observed for all oxides with the cubic crystal structure. It was proposed that a decisive role in this difference belongs to a local symmetry in the position of O atoms. 相似文献
76.
77.
在相对碰撞平动能为 0 .0 5eV的分子束实验条件下 ,研究了亚稳态CO(a) +NO(X)的E E传能通道 .通过测量和分析交碰区的传能发射光谱 ,在 780和 860nm处观测到了NO(b -a)跃迁Ogawa带的△v =+ 4和△v =+ 3序的发射光谱 .从而首次在实验上直接证实了传能过程中第四通道的存在 (CO (a) +NO(X)→CO (X) +NO(b) ) .这一通道的发现解释了前人测量到的在CO(a)与NO(X)碰撞传能过程中CO(a)的猝灭速率远大于NO(A ,B)生成速率的实验结果 ,并进一步证实了这一“经典”E E传能体系为电子交换机理的传能观点 相似文献
78.
T. Tsuneta T. Toshima K. Inagaki T. Shibayama S. Tanda S. Uji M. Ahlskog P. Hakonen M. Paalanen 《Current Applied Physics》2003,3(6):473-476
We succeed in synthesizing NbSe2 nanotubes along with nanofibers by chemical vapor transportation. They are stable crystalline systems and can be synthesized reproducibly in a nearly equilibrium reacting process. We have investigated these nanosize structures of NbSe2 by transmission electron microscopy and electron diffraction. Both of the structures have a similar size of 100–200 nm in diameter. While nanotubes consist of rolled-up NbSe2 layers, nanofibers are a pile of thin flat layers. We propose a mechanism of the formation of NbSe2 nanotubes and nanofibers on the basis of deseleniditive transition from a NbSe3 fiber-shaped crystal. We also measured electrical resistance of the nanofibers with conductive atomic force microscopy and demonstrated that the material show metallic behavior at room temperature. 相似文献
79.
Scanning probe microscopy characterization of gold-chemisorbed poplar plastocyanin mutants 总被引:1,自引:0,他引:1
L. Andolfi B. Bonanni G. W. Canters M. Ph. Verbeet S. Cannistraro 《Surface science》2003,530(3):181-194
Two poplar plastocyanin mutants adsorbed onto gold electrodes have been characterized at single molecule level by scanning probe microscopy. Immobilization of the two redox metalloprotein mutants on Au(1 1 1) surface was achieved by either a disulphide bridge (PCSS) or a single thiol (PCSH), both the anchoring groups having been introduced by site-directed mutagenesis. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) analysis gives evidence of a stable and robust binding of both mutants to gold. The lateral dimensions, as estimated by STM, and the height above the gold substrate, as evaluated by AFM, of the two mutants well agree with crystallographic sizes. A narrower height distribution is observed for PCSS compared to PCSH, corresponding to a more homogeneous orientation of the former mutant adsorbed onto gold. Major differences between the mutants are observed by electrochemical STM. In particular, the image contrast of adsorbed PCSS is affected by tuning the external electrochemical potential to the redox levels of the mutant, consistent with some involvement of copper active site in the tunneling process. On the contrary, no contrast variation is observed in electrochemical STM of adsorbed PCSH. Moreover, scanning tunneling spectroscopy experiments reveal asymmetric I–V characteristics for single PCSS proteins, reminiscent of a rectifying-like behaviour, whereas an almost symmetric I–V relation is observed for PCSH. 相似文献
80.
掺Perylene的PVK薄膜荧光谱及发光机理 总被引:1,自引:1,他引:0
用高荧光效率的有机染料芘(perylene)掺杂聚乙烯咔唑(PVK),其荧光光谱与芘的发射光谱基本一致,而且亮度比纯芘发光提高十多倍,说明发光主要来自芘分子,并在PVK和perylene之间存在十分有效的能量传递或电荷转移过程,荧光谱强度随掺杂浓度的变化关系说明存在一个最佳的掺杂浓度比.分析PVK和perylene之间可能发生的能量转移过程,认为从PVK到perylene这种能量转移与实验不符;分析PVK和perylene薄膜的光致发光过程,认为从(PVK+)→(perylene+)和从(PVK-)→(p 相似文献