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211.
研究了脉冲激发下单个半导体量子点中单光子发射的统计特性.在旋转波近似条件下,由系统粒子数演化主方程并结合量子回归理论推导了二阶相关函数的运动方程,利用此方程讨论了二阶相关函数随输入脉冲面积的关系.在窄脉冲宽度的脉冲激发下,单光子的发射概率p和效率η都随着强度的增强而产生振荡.研究表明,采用窄脉冲宽度,当输入脉冲面积在π附近时可以得到较高的单光子发射效率.
关键词:
半导体量子点
单光子发射
三能级系统 相似文献
212.
受自然界树型结构的启发,设计了分叉树型微结构单元,用电路板刻蚀技术制作了非对称开口六边形谐振单环及其组合结构.采用计算机模拟和实验研究了单个和多个谐振环在微波段(7—12 GHz)的电磁响应行为.研究结果表明:该结构具有负磁导率特性,开口谐振环几何尺寸影响环的磁谐振频率;两环环间距较小时出现二次谐振;带高级分支的辐射状环列相对于不带分支环列透射峰向低频移动.实验和模拟结果相符.
关键词:
负磁导率
开口谐振环
透射率 相似文献
213.
根据超短光脉冲在光纤中传输的非线性薛定谔方程,模拟了不同色散参量情况下色散补偿和色散位移光纤对增益开关半导体激光器产生的光脉冲的压缩,给出了光脉冲在经过色散补偿光纤前后的啁啾曲线。结果表明,使用色散参量D分别为-150,-180和-20ps/(nm·km)的色散补偿光纤可以实现其他脉冲压缩方法的压缩效果,最大压缩因子达到6.09,但色散参量越大,所需光纤长度就越短。此外,脉冲经过色散补偿光纤后线性啁啾几乎为零。还利用色散位移光纤对脉冲进行孤子压缩,脉冲宽度由最初的45ps减小到1.23ps。指出采用这2种光纤相结合的方法可以对光脉冲实现高效压缩。 相似文献
214.
Quaternions are an important tool that provides a convenient and effective mathematical method for representing reflections and rotations in three-dimensional space. A unit timelike split quaternion represents a rotation in the Lorentzian space. In this paper, we give some geometric interpretations of split quaternions for lines and planes in the Minkowski 3-space with the help of mutual pseudo orthogonal planes. We classified mutual planes with respect to the casual character of the normals of the plane as follows; if the normal is timelike, then the mutual plane is isomorphic to the complex plane; if the normal is spacelike, then the plane is isomorphic to the hyperbolic number plane (Lorentzian plane); if the normal is lightlike, then the plane is isomorphic to the dual number plane (Galilean plane). 相似文献
215.
The vacuum Rabi splitting and Kerr effect are investigated theoretically in a hybrid spin–magnon–photon system, where the nitrogen-vacancy center in diamond driven by two light fields is coupled to a spherical micromagnet embedded in a superconducting coplanar waveguide resonator. The results indicate that the phenomenon of the Mollow triplet and vacuum Rabi splitting can appear by controlling the spin–magnon coupling and magnon–photon coupling. It is shown that the probe absorption spectrum can be adjusted effectively via the pump frequency detuning. Moreover, it is demonstrated that the optical Kerr effect can be tuned by changing the Rabi frequency. This work may provide a possibility for the applications in quantum information processing and quantum sensing of magnetic signal. 相似文献
216.
Dr. Aleksander Rebane Geoffrey Wicks Dr. Mikhail Drobizhev Dr. Thomas Cooper Aleksander Trummal Dr. Merle Uudsemaa 《Angewandte Chemie (International ed. in English)》2015,54(26):7582-7586
We present a new approach for determining the strength of the dipolar solute‐induced reaction field, along with the ground‐ and excited‐state electrostatic dipole moments and polarizability of a solvated chromophore, using exclusively one‐photon and two‐photon absorption measurements. We verify the approach on two benchmark chromophores N,N‐dimethyl‐6‐propionyl‐2‐naphthylamine (prodan) and coumarin 153 (C153) in a series of toluene/dimethyl sulfoxide (DMSO) mixtures and find that the experimental values show good quantitative agreement with literature and our quantum‐chemical calculations. Our results indicate that the reaction field varies in a surprisingly broad range, 0–107 V cm?1, and that at close proximity, on the order of the chromophore radius, the effective dielectric constant of the solute–solvent system displays a unique functional dependence on the bulk dielectric constant, offering new insight into the close‐range molecular interaction. 相似文献
217.
π‐Expanded α,β‐Unsaturated Ketones: Synthesis,Optical Properties,and Two‐Photon‐Induced Polymerization 下载免费PDF全文
Rashid Nazir Dr. Florent Bourquard Evaldas Balčiūnas Dr. Sabina Smoleń Dr. David Gray Prof. Dr. Nikolai V. Tkachenko Dr. Maria Farsari Prof. Dr. Daniel T. Gryko 《Chemphyschem》2015,16(3):682-690
A library of π‐expanded α,β‐unsaturated ketones was designed and synthesized. They were prepared by a combination of Wittig reaction, Sonogashira reaction, and aldol condensation. It was further demonstrated that the double aldol condensation can be performed effectively for highly polarized styrene‐ and diphenylacetylene‐derived aldehydes. The strategic placement of two dialkylamino groups at the periphery of D ‐π‐A‐π‐D molecules resulted in dyes with excellent solubility. These ketones absorb light in the region 400–550 nm. Many of them display strong solvatochromism so that the emission ranges from 530–580 nm in toluene to the near‐IR region in benzonitrile. Ketones based on cyclobutanone as central moieties display very high fluorescence quantum yields in nonpolar solvents, which decrease drastically in polar media. Photophysical studies of these new functional dyes revealed that they possess an enhanced two‐photon absorption cross section when compared with simpler ketone derivatives. Due to strong polarization of the resulting dyes, values of two‐photon absorption cross sections on the level of 200–300 GM at 800 nm were achieved, and thanks to that as well as the presence of the keto group, these new two‐photon initiators display excellent performance so that the operating region is 5–75 mW in some cases. 相似文献
218.
Differentiation between Shallow and Deep Charge Trap States on Single Poly(3‐hexylthiophene) Chains through Fluorescence Photon Statistics 下载免费PDF全文
Kristin S. Grußmayer Florian Steiner Prof. Dr. John M. Lupton Prof. Dr. Dirk‐Peter Herten Dr. Jan Vogelsang 《Chemphyschem》2015,16(17):3578-3583
Blinking of the photoluminescence (PL) emitted from individual conjugated polymer chains is one of the central observations made by single‐molecule spectroscopy (SMS). Important information, for example regarding excitation energy transfer, can be extracted by evaluating dynamic quenching. However, the nature of trap states, which are responsible for PL quenching, often remains obscured. We present a detailed investigation of the photon statistics of single poly(3‐hexylthiophene) (P3HT) chains obtained by SMS. The photon statistics provide a measure of the number and brightness of independently emitting areas on a single chain. These observables can be followed during blinking. A decrease in PL intensity is shown to be correlated with either 1) a decrease in the average brightness of the emitting sites; or 2) a decrease in the number of emitting regions. We attribute these phenomena to the formation of 1) shallow charge traps, which can weakly affect all emitting areas of a single chain at once; and 2) deep traps, which have a strong effect on small regions within the single chains. 相似文献
219.
Diketopyrrolopyrrole‐Porphyrin Conjugates with High Two‐Photon Absorption and Singlet Oxygen Generation for Two‐Photon Photodynamic Therapy 下载免费PDF全文
Julie Schmitt Prof. Valérie Heitz Dr. Angélique Sour Dr. Frédéric Bolze Dr. Hussein Ftouni Prof. Jean‐Francois Nicoud Dr. Lucia Flamigni Dr. Barbara Ventura 《Angewandte Chemie (International ed. in English)》2015,54(1):169-173
Two‐photon photodynamic therapy is a promising therapeutic method which requires the development of sensitizers with efficient two‐photon absorption and singlet‐oxygen generation. Reported here are two new diketopyrrolopyrrole‐porphyrin conjugates as robust two‐photon absorbing dyes with high two‐photon absorption cross‐sections within the therapeutic window. Furthermore, for the first time the singlet‐oxygen generation efficiency of diketopyrrolopyrrole‐containing systems is investigated. A preliminary study on cell culture showed efficient two‐photon induced phototoxicity. 相似文献
220.
Inside Back Cover: Differentiation between Shallow and Deep Charge Trap States on Single Poly(3‐hexylthiophene) Chains through Fluorescence Photon Statistics (ChemPhysChem 17/2015) 下载免费PDF全文