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981.
Ying‐Hui Wang Li‐Jing Gong Wen‐Yue Dong Ping Lu Zhi‐Hui Kang Tian‐Hao Huang Yu‐Guang Ma Han‐Zhuang Zhang 《Journal of Polymer Science.Polymer Physics》2013,51(12):992-997
The photoexcitation processes of two donor–acceptor‐type copolymers PCFBT with different ratios between the donor and the acceptor ( PCFBT0.5 and PCFBT0.1 ) in the solution system are systematically studied. If the number of the donor is equal to that of the acceptor in one repeat unit (such as PCFBT0.5 ), intrachain charge transfer (ICT) can occur and participate in the relaxation of the excited state after photoexcitation. When the number of donors is much larger than that of acceptors (such as PCFBT0.1 ) in one repeat unit, the ICT character can disappear, and the localized exciton decay process is dominant in the relaxation of the copolymer, which also involves an excitation intensity‐independent vibrational thermal relaxation process at the initial time. The results further the understanding of the basic structure‐property relationship. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 992–996 相似文献
982.
The main objective of this article is to study the dynamic phase transitions associated with the spatial–temporal oscillations of the BZ reactions, given by Field, Körös and Noyes, also referred as the Oregonator. Two criteria are derived to determine (1) the existence of either multiple equilibria or spatiotemporal oscillations and (2) the types of transitions. These criteria gives a complete characterization of the dynamic transitions of the BZ systems from the homogeneous states. The analysis is carried out using a dynamic transition theory developed recently by the authors, which has been successfully applied to a number of problems in science. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
983.
Li Gaoliang He Hui Zheng Weifang Tang Hongbin Li Huirong Lan Tian Liu Xiechun Zhang Hu Yang He Luo Fangxiang Xiao Songtao Ye Guoan 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):279-284
Oxidation of Pu(III) in 1 bp solution to Pu(IV) was studied using the salt-free oxidant N2O4. It was proved that the reductants N,N-dimethylhydroxylamine (DMHAN) and monomethyl-hydrazine (MMH) present in 1 bp solution of CIAE-APOR process can be oxidized and removed from the solutions also by N2O4 before the oxidation of Pu(III). The effects of the acidity, the temperature and the amount of N2O4 added on the oxidation of DMHAN and MMH were studied. 相似文献
984.
Guang-hui Tian Cun-fang Liu Pu-hui Lai Hua Zhao Feng Nie 《Chemistry of Natural Compounds》2010,46(2):219-221
Taibaihenryiin T was isolated for the first time from Phlomis umbrosa Turcz, and its structure was elucidated on the basis of IR and NMR spectra analysis. Its molecular configuration, conformation,
and crystal structure were also characterized by X-ray structure analysis. The infrequency of the C–O–O–C group is manifested
in this molecular configuration, and hydrogen bonding assembles the molecules into a three-dimensional networking structure
in the crystal. 相似文献
985.
Wen-Rui Shan Bo Tian 《Communications in Nonlinear Science & Numerical Simulation》2012,17(12):4559-4564
Variable-coefficient nonlinear evolution equations have occurred in such fields as plasma physics, arterial mechanics, nonlinear optics and Bose–Einstein condensates. This paper is devoted to giving some transformations to convert the original nonlinear evolution equations, e.g., the variable-coefficient nonlinear Schrödinger, generalized Gardner and variable-coefficient Sawada–Kotera equations to simpler ones or even constant-coefficient ones. Based on some constraints, we simplify the original equations and derive the associated chirp solitons, Lax pairs, and Bäcklund transformations from the original equations by means of the aforementioned transformations. 相似文献
986.
987.
Chengzhi Chuai Mahmood Iqbal Shixiong Tian 《Journal of Polymer Science.Polymer Physics》2010,48(3):267-275
Graft copolymerization of low‐density polyethylene (LDPE) with a maleic anhydride (MAH) was performed using intermeshing corotating twin‐screw extruder in the presence of benzoyl peroxide (BPO). The LDPE/polyamide 6 (PA6) and LDPE‐g‐MAH/PA6 blends were prepared in a corotating twin‐screw extruder. The melt viscosity of the grafted LDPE was measured by a capillary rheometer. The grafted copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microcopy (SEM). The influence of the variation in temperature, BPO and MAH concentration, and temperature on the grafting degree and on the melt viscosity was studied. The grafting degree increased appreciably up to about 0.45 phr and then decreased continuously with an increasing BPO concentration. According to the FTIR analysis, it was found that the amount of grafted MAH on the LDPE chains was ~5.1%. Thermal analysis showed that melting temperature of the graft copolymers decreases with increasing grafting degree. In addition to this, loss modulus (E″) of the copolymers first increased little with increasing grafting and then obviously decreased with increasing grafting degree. Furthermore, the results revealed that the tensile strength of the blends increased linearly with increasing PA6 content. The results of SEM and mechanical test showed that the blends have good interfacial adhesion and good stability of the phase structure, which is reflected in the mechanical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 267–275, 2010 相似文献
988.
989.
Jiacong Guo Yankun Zhang Dr. Guofeng Tian Prof. Deyang Ji Prof. Shengli Qi Prof. Dezhen Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(49):12526-12534
Polyimide memory materials with a donor–acceptor structure based on a charge-transfer mechanism exhibit great potential for next-generation information storage technology due to their outstanding high-temperature resistance and good dimensional and chemical stability. Precisely controlling memory performance by limited chemical decoration is one of core challenges in this field. Most reported work mainly focuses on designing novel and elaborate electron donors or acceptors for the expected memory behavior of polyimides; this takes a lot of time and is not always efficacious. Herein, we report a series of porphyrinated copolyimides coPI−Znx (x=5, 10, 20, 50, 80), where x represents the mole percentage of Zn ion in the central core of the porphyrin. Experimental and theoretical analysis indicate that the Zn ion could play a vital bridge role in promoting the formation and stabilization of a charge-transfer complex by enhancing the hybridization of local and charge transfer (HLCT) excitations of porphyrinated polyimides, endowing coPI−Znx with volatile random access memory performance and continuously tunable retention time. This work could provide one simple strategy to precisely regulate memory performance merely by altering the metal content in porphyrinated polyimides. 相似文献