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91.
Dr. Igor O. Koshevoy Yuh‐Chia Chang Dr. Antti J. Karttunen Julia R. Shakirova Prof. Janne Jänis Prof. Matti Haukka Prof. Tapani Pakkanen Prof. Pi‐Tai Chou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(16):5104-5112
A new series of homoleptic alkynyl complexes, [{Au2Cu2(C2R)4}n] (R=C3H7O ( 1 ), C6H11O ( 2 ), C9H19O ( 3 ), C13H11O ( 4 )), were obtained from Au(SC4H8)Cl, Cu(NCMe)4PF6, and the corresponding alkyne in the presence of a base (NEt3). Complexes 1 – 4 aggregate upon crystallization into polymeric chains through extensive metallophilic interactions. The cluster that contains fluorenolyl functionalities, C13H9O ( 5 ), crystallizes in its molecular form as a disolvate, [Au2Cu2(C2C13H9O)4] ? 2 THF. The substitution of weakly bound THF molecules with pyridine molecules leads to the complex [Au2Cu2(C2C13H9O)4] ? 2 py ( 6 ), thus giving two polymorphs in the solid state. Such structural diversity is established through metal‐chain and hydrogen‐bond formation, which depends on the stereochemical characteristics of the organic ligands. More interestingly, this solid‐state structural arrangement affords good emission properties, such as intensity and spectroscopic profile, which are otherwise very weakly emissive in solution. Metallophilic aggregation of the {Au2Cu2} cluster units, as observed in the crystals, results in dramatic enhancement of the room‐temperature phosphorescence, thereby reaching a maximum quantum efficiency of 95 % ( 4 ). A theoretical approach further indicates a synergistic effect of the array of the metal chain upon aggregation, which greatly enhances the spin‐orbit coupling and, hence, the phosphorescence, thereby opening up a new direction in the field of aggregate‐enhanced emission. 相似文献
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Esa Toukoniitty Päivi Mäki-Arvela Ahmad Kalantar Neyestanaki Ensio Laine Jyri-Pekka Mikkola Tapio Salmi Dmitry Yu. Murzin 《Reaction Kinetics and Catalysis Letters》2001,73(1):3-11
In the presence of ultrasound both the initial hydrogenation rate of 1-phenyl-1,2- propanedione and the enantiomeric excess of the main product, i.e. (R)-1-hydroxy- 1-phenylpropanone, increased by 75 % and 52 % in toluene, respectively, as compared to the silent hydrogenation. 相似文献
94.
Accelerated beam tracing algorithm 总被引:1,自引:0,他引:1
Determining early specular reflection paths is essential for room acoustics modeling. Beam tracing algorithms have been used to calculate these paths efficiently, thus allowing modeling of acoustics in real-time with a moving listener in simple, or complex but densely occluded, environments with a stationary sound source. In this paper, it is shown that beam tracing algorithms can still be optimized by utilizing the spatial coherence in path validation with a moving listener. Since the precalculations required for the presented technique are relatively fast, the acoustic reflection paths can be calculated even for a moving source in simple cases. Simulations were performed to show how the accelerated algorithm compares with the basic algorithm with varying scene complexity and occlusion. Up to two-orders of magnitude speed-up was achieved. 相似文献
95.
The octaanion, [OSiO1.5]88? (OA) is a low cost, discrete nano silica particle that can be made directly from high surface area, amorphous silica reacted with Me4NOH in water alcohol mixtures. It would be ideal if Me4NOH could be formed in situ from, for example, Me4NCl and NaOH, as long known in the literature. This process would reduce costs and enable recycling of Me4NCl produced in the functionalization of OA with chlorosilanes, RMe2SiCl, to form [RMe2SiOSiO1.5]8 organic/inorganic hybrid nanobuilding blocks. Kinetic studies were conducted to assess base‐promoted dissolution of fumed silica (25 m 2 /g) as a function of concentrations, times, etc., to form the octaanion [OSiO1.5]88? using Me4NOH, NaOH and mixtures of NaOH/Me4NCl. Surprisingly, we find that small amounts of Me4NCl greatly inhibit the dissolution reaction for reasons that are as yet unknown. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
96.
Y. Burnier M. Laine L. Mether 《The European Physical Journal C - Particles and Fields》2011,71(4):1619
Some time ago, Cuniberti et al. have proposed a novel method for analytically continuing thermal imaginary-time correlators
to real time, which requires no model input and should be applicable with finite-precision data as well. Given that these
assertions go against common wisdom, we report on a naive test of the method with an idealized example. We do encounter two
problems, which we spell out in detail; this implies that systematic errors are difficult to quantify. On a more positive
note, the method is simple to implement and allows for an empirical recipe by which a reasonable qualitative estimate for
some transport coefficient may be obtained, if statistical errors of an ultraviolet-subtracted imaginary-time measurement
can be reduced to roughly below the per mille level. 相似文献
97.
Jessica A. Rumfeldt Heikki Takala Alli Liukkonen Janne A. Ihalainen 《Photochemistry and photobiology》2019,95(4):969-979
Red‐light photosensory proteins, phytochromes, link light activation to biological functions by interconverting between two conformational states. For this, they undergo large‐scale secondary and tertiary changes which follow small‐scale Z to E bond photoisomerization of the covalently bound bilin chromophore. The complex network of amino acid interactions in the chromophore‐binding pocket plays a central role in this process. Highly conserved Y263 and H290 have been found to be important for the photoconversion yield, while H260 has been identified as important for bilin protonation and proton transfer steps. Here, we focus on the roles these amino acids are playing in preserving the chemical properties of bilin in the resting Pr state of the photosensory unit of a bacteriophytochrome from Deinococcus radiodurans. By using pH‐dependent UV‐Vis spectroscopy and spectral decomposition modeling, we confirm the importance of H260 for biliverdin protonation. Further, we demonstrate that in the canonical bacteriophytochromes, the pKa value of the phenol group of the Y263 is uncommonly low. This directly influences the protonation of the bilin molecule and likely the functional properties of the protein. Our study expands the understanding of the tight interplay between the nearby amino acids and bilin in the phytochrome family. 相似文献
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100.
Janne Heittokangas Katsuya Ishizaki Kazuya Tohge Zhi-Tao Wen 《Israel Journal of Mathematics》2018,227(1):397-421
An exponential polynomial of order q is an entire function of the form where the coefficients Pj(z),Qj(z) are polynomials in z such that It is known that the majority of the zeros of a given exponential polynomial are in domains surrounding finitely many critical rays. The shape of these domains is refined by showing that in many cases the domains can approach the critical rays asymptotically. Further, it is known that the zeros of an exponential polynomial are always of bounded multiplicity. A new sufficient condition for the majority of zeros to be simple is found. Finally, a division result for a quotient of two exponential polynomials is proved, generalizing a 1929 result by Ritt in the case q = 1 with constant coefficients. Ritt’s result is closely related to Shapiro’s conjecture that has remained open since 1958.
相似文献
$$g(z) = {P_1}(z){e^{{Q_1}(z)}} + ...{P_k}(z){e^{{Q_k}(z)}},$$
$$\max \{ deg({Q_j})\} = q.$$