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141.
142.
A 2D photonic crystal optical switch is proposed based on a rods-in-air square-lattice photonic crystal by removing two cross-lines of rods from a 2D square-lattice photonic crystal to form four optical channels. The simulation results show that, when inserting a single rod along the diagonal line of the intersection area of two removed cross-lines of rods, the position of the single inserted rod determines how much incident energy goes into different channels. In the case of transverse magnetic (TM) Gaussian point source, time domain simulation shows that up to 87.3% of the incident energy can be switched into a channel, which is vertical to the source channel. Because there are two diagonal lines in the intersection area of two removed cross-lines of rods, the optical switch feature is achieved by shifting the inserted rod between two diagonal lines. It is also found that the magnitude of the reflected wave in the source channel varies greatly with spatial position of the single inserted rod. The larger the magnitude of the reflected wave in the source channel, the less the energy that goes into the switched channel. The time delay between the incident wave and the reflected wave in the source channel is also related to the position of the single inserted rod. In addition, the large time delay between the incident wave and the reflected wave in the source channel shows that the reflected wave encounters many reflections with the walls of the source channel, instead of waves reflected back from the single inserted rod. 相似文献
143.
Juntao Li Hari Krishna Bisoyi Siyang Lin Jinbao Guo Quan Li 《Angewandte Chemie (International ed. in English)》2019,58(45):16052-16056
Reported here is the first example of a 1,2‐dithienyldicyanoethene‐based visible‐light‐driven chiral fluorescent molecular switch that exhibits reversible trans to cis photoisomerization. The trans form in solution almost completely transforms into the cis form, accompanied by a 10‐fold decrease in its fluorescence intensity within 60 seconds when exposed to green light (520 nm). The reverse isomerization proceeds upon irradiation with blue light (405 nm). When doped into commercially available achiral liquid crystal hosts, this molecular switch efficiently induces luminescent helical superstructures, that is, a cholesteric phase. The intensity of the circularly polarized fluorescence as well as the selective reflection wavelength of the induced cholesteric phases can be reversibly tuned using visible light of two different wavelengths. Optically rewritable photonic devices using cholesteric films containing this molecular switch are described. 相似文献
144.
Xiaofei Chen Christian Mevissen Saskia Huda Christian Gb Iris M. Oppel Markus Albrecht 《Angewandte Chemie (International ed. in English)》2019,58(37):12879-12882
Two biscatecholester ligands with oligoether spacers were used to prepare dinuclear titanium(IV) triscatecholate based helicates. In the case of Li4[( 1 / 2 )3Ti2], “classical” helicates with three internally bound Li+ ions and syn‐oriented ligands in the complex units (fac/fac isomer) were obtained. In the case of the sodium salt Na4[( 2 )3Ti2], a different homochiral dinuclear triple‐stranded helicate with two internally bound Na+ ions was formed. The complex units are anti‐configured, and two of the ligand spacers are connecting internal with external positions of the helicate (mer/mer isomer). Removal of the sodium ions and addition of lithium ions leads to the switching from one topology to the other with an expanded helicate [( 2 )3Ti2]4? as an intermediate. Switching back to the “non‐classical” helicate cannot be observed because severe structural rearrangements would be required. 相似文献
145.
杨善晓 《浙江大学学报(理学版)》2009,36(2)
针对硬件实现模糊控制表查询电路存在结构复杂、用数字式设计困难等问题,提出了将模糊控制表转换为多值K图,在此基础上结合传输开关理论采用电流型CMOS设计模糊控制表查询电路的方法,并用此方法具体设计了一个5元素-论域的电流型CMOS模糊控制表查询电路.通过对设计实例的PSPICE仿真,表明本文提出的设计方法简单易行,设计的电流型CMOS查询电路具有结构简单和高速推理的优点. 相似文献
146.
杨善晓 《浙江大学学报(理学版)》2009,36(2):165-169
针对硬件实现模糊控制表查询电路存在结构复杂、用数字式设计困难等问题,提出了将模糊控制表转换为多值K图,在此基础上结合传输开关理论采用电流型CMOS设计模糊控制表查询电路的方法.并用此方法具体设计了一个5元素论域的电流型CMOS模糊控制表查询电路.通过对设计实例的PSPICE仿真,表明本文提出的设计方法简单易行,设计的电流型CMOS查询电路具有结构简单和高速推理的优点。 相似文献
147.
Modification of Fluorescent Photoinduced Electron Transfer (PET) Sensors/Switches To Produce Molecular Photo‐Ionic Triode Action
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Dr. Allen J. M. Huxley Dr. Marc Schroeder Dr. H. Q. Nimal Gunaratne Prof. Dr. A. Prasanna de Silva 《Angewandte Chemie (International ed. in English)》2014,53(14):3622-3625
The fluorophore‐spacer1‐receptor1‐spacer2‐receptor2 system (where receptor2 alone is photoredox‐inactive) shows ionically tunable proton‐induced fluorescence off‐on switching, which is reminiscent of thermionic triode behavior. This also represents a new extension to modular switch systems based on photoinduced electron transfer (PET) towards the emulation of analogue electronic devices. 相似文献
148.
149.
Ya E. Krasik K. Chirko J. Z. Gleizer A. Krokhmal A. Dunaevsky J. Felsteiner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):89-95
In this paper the parameters of two types of high-current switches based on ferroelectric BaTiO3 ignition are presented. Both types of switches showed a reliable and controllable operation with a repetition rate of several
Hz. The first type is a vacuum two-electrode switch ignited by the plasma which is generated by a BaTiO3 cathode. This type of switch was tested in the voltage range of 3-25 kV and switched current amplitude of 2-15 kA with either
negative or positive polarity of the high-voltage electrode. The second type is a BaTiO3 surface flashover strip-like switch ignited by a driving pulse which has an amplitude of several kV. It was shown that the
application of the driving pulse (>10 kV) leads to the appearance of many non-complete surface discharges which transform
further to a multi-channel discharge. This type of switch was tested in the voltage range of 1-25 kV and current amplitude
of 0.5-15 kA. The design of the switches, their lifetime, the time jitter and the parameters of the switched current for different
discharge conditions are presented.
Received 5 November 2001 相似文献
150.
Markus Frei Franois Diederich Rolando Tremont Tanya Rodriguez Luis Echegoyen 《Helvetica chimica acta》2006,89(9):2040-2057
We report the synthesis of novel resorcin[4]arene‐based cavitands featuring two extended bridges consisting of quinoxaline‐fused TTF (tetrathiafulvalene) moieties. In the neutral form, these cavitands were expected to adopt the vase form, whereas, upon oxidation, the open kite geometry should be preferred due to Coulombic repulsion between the two TTF radical cations (Scheme 2). The key step in the preparation of these novel molecular switches was the P(OEt)3‐mediated coupling between a macrocyclic bis(1,3‐dithiol‐2‐thione) and 2 equiv. of a suitable 1,3‐dithiol‐2‐one. Following the successful application of this strategy to the preparation of mono‐TTF‐cavitand 3 (Scheme 3), the synthesis of the bis‐TTF derivatives 2 (Scheme 4) and 19 (Scheme 5) was pursued; however, the target compounds could not be isolated due to their insolubility. Upon decorating both the octol bowl and the TTF cavity rims with long alkyl chains, the soluble bis‐TTF cavitand 23 was finally obtained, besides a minor amount of the novel cage compound 25a featuring a highly distorted TTF bridge (Scheme 6). In contrast to 25a , the deep cavitand 23 undergoes reversible vase → kite switching upon lowering the temperature from 293 to 193 K (Fig. 1). Electrochemical studies by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) provided preliminary evidence for successful vase → kite switching of 23 induced by the oxidation of the TTF cavity walls. 相似文献