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191.
Dan-Li Hong Dr. Yang-Hui Luo Xiao-Tong He Zi-Yue Zheng Shan Su Jia-Ying Wang Cong Wang Chen Chen Prof. Bai-Wang Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(37):8805-8812
Precise revealing the mechanisms of excited-state intermolecular proton transfer (ESPT) and the corresponding geometrical relaxation upon photoexcitation and photoionization remains a formidable challenge. In this work, the compound (E)-4-(((4H-1,2,4-triazol-4-yl)imino)methyl)-2,6-dimethoxyphenol (TIMDP) adopting a D-π-A molecular architecture featuring a significant intramolecular charge transfer (ICT) effect has been designed. With the presence of perchloric acid (35 %), TIMDP can be dissolved through the formation of a HClO4–H2O–OH(TIMDP)–N(TIMDP) hydrogen-bonding bridge. At the ground state, the ICT effect is dominant, giving birth to crystals of TIMDP. Upon external stimuli (e.g., UV light irradiation, electro field), the excited state is achieved, which weakens the ICT effect, and significantly promotes the ESPT effect along the hydrogen-bonding bridge, resulting in crystals of [HTIMDP]+ ⋅ [H2O] ⋅ [ClO4]−. As a consequence, the mechanisms of the ESPT can be investigated, which distorted the D-π-A molecular architecture, tuned the emission color with the largest Stokes shift of 242 nm, and finally, high photoluminescence quantum yields (12 %) and long fluorescence lifetimes (8.6 μs) have achieved. These results not only provide new insight into ESPT mechanisms, but also open a new avenue for the design of efficient ESPT emitters. 相似文献
192.
Dr. Wenyan Hao Yuchen Sha Dr. Yi Deng Yi Luo Li Zeng Shan Tang Dr. Yue Weng Prof. Dr. Chien-Wei Chiang Prof. Dr. Aiwen Lei 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(19):4931-4934
An in situ generated oxidation species of nickel quinolinylpropioamide intermediate was produced. Characterization by X-ray absorption near edge structure (XANES) and EPR provides complementary insights into this oxidized nickel species. With aliphatic amides and isocyanides as substrates, a nickel-catalyzed facile synthesis of structurally diverse five-membered lactams could be achieved. 相似文献
193.
A comprehensive study on the efficient one‐pot synthesis of polyhedral octaphenylsilsesquioxane (OPS) is reported via the hydrolytic condensation of phenyltrimethoxysilane (PTMS) in the presence of basic catalyst to investigate the specific synthesis mechanism. The synthetic reactions are monitored with real time infrared (RTIR) spectroscopy. Then RTIR coupled with 29Si nuclear magnetic resonance spectroscopy (NMR) and matrix‐assisted laser desorption/ionization time of flight mass spectrometry (MALDI‐TOF‐MS) are used to monitor the reactions and identify the intermediary species during the reaction. The rapid hydrolysis of PTMS is detected by RTIR. Contrary to previous reports, the ladder‐like structured species are identified as intermediates during the reaction process. It is suggested that formation of caged T8 OPS is realized through the chain break and rearrangement of the ladder‐like phenyltrimethoxysilanes. Accordingly, a scheme from hydrolysis of the PTMS to formation of the OPS is provided. 相似文献
194.
BinBin Xiao NaiZhou Wang Chao Shang FanBao Meng JianWen Ding Bin Lei XiGang Luo 《中国科学:物理学 力学 天文学(英文版)》2019,(4)
The origin of the ~40 and ~30 K superconducting phases in the metal-intercalated FeSe superconductors is still unclear. We report the synthesis of K_(0.3)(NH_3)_y(FeSe_(1-x)Te_x)_2 and K_(0.6)(NH_3)_y(FeSe_(1-x)Te_x)_2 with x=0-0.6 by using the liquid ammonia method at room temperature. The superconducting transition temperature Tcof the former remains about 43 K for all the nominal Te content less than 0.3, while that of the latter is about 30 K and obviously decreases with Te doping. Superconductivity disappears for x ≥0.4 in both systems. Except for the different chemical pressure induced by substitution of Te for Se in both systems, we also observed distinct external pressure effect on superconductivity for both systems, with much more efficiency of suppressing Tcby external pressure in the former system. These dramatic differences of both chemical and external pressure effects on Tc between the ~30 and ~40 K superconducting phases revealed that the existence of the two superconducting phases can be ascribed to the moderate and negligible coupling between FeSe layers, respectively. 相似文献
195.
YongGuang Tu GuoNing Xu XiaoYu Yang YiFei Zhang ZhaoJie Li Rui Su DeYing Luo WenQiang Yang Ying Miao Rong Cai LuHua Jiang XiaoWei Du YanChu Yang QianShi Liu Yang Gao Shuai Zhao Wei Huang QiHuang Gong Rui Zhu 《中国科学:物理学 力学 天文学(英文版)》2019,(7)
<正>The metal halide perovskite materials demonstrate outstanding performance in photovoltaics because of their excellent optoelectronic properties [1-7]. The perovskite solar cells (PSCs) exhibiting outstanding efficiency [8,9], high power-per-weight [10], and excellent radiation resistance[11-13] are considered to be promising for developing the new-generation energy technology for space application.However, the extreme space environment would impose 相似文献
196.
Transport in Porous Media - Compositional displacements in porous media, where chemical components partition between phases during a displacement, occur in flow processes such as surfactant... 相似文献
197.
Nonlinear Dynamics - A finite element model of the cantilever combined support rotor included two discs established in this paper to predict and explain the nonlinear vibration phenomenon. The... 相似文献
198.
Nonlinear Dynamics - This article investigates the exponential ultimate boundedness of fractional-order differential systems via periodically intermittent control. By utilizing the Lyapunov... 相似文献
199.
A library of rare-earth metal derivatives supported by an aminophenoxy ligand was prepared and their catalytic performance in lactide polymerization was investigated. It was found that the synthetic strategy had a profound effect on the formation of aminophenoxy rare-earth metal complexes. Amine elimination between Ln[N(SiMe3)2]3(μ-Cl)Li(THF)3 (Ln = Yb, Y) and 1 equiv. of the aminophenol [HONH] ([HONH] = ο-OCH3-C6H4NHCH2(3,5-tBu2-C6H2-2-OH)) in toluene gave the unexpected heterobimetallic bis(aminophenoxy) rare-earth metal complexes [ON]2LnLi(THF)2 (Ln = Yb ( 1 ), Y ( 2 )). When the reactions were carried out in THF and TMEDA, amine elimination produced the aminophenoxy rare-earth metal amide complexes {[ON]LnN(SiMe3)2}2 (Ln = Yb ( 5 ), Y ( 6 )) in ca 85% isolated yields. Complexes 5 and 6 could also be obtained from salt metathesis reaction of {[ON]LnCl(THF)}2 (Ln = Yb ( 3 ), Y ( 4 )) with NaN(SiMe3)2 in a 1:2 molar ratio. In addition, treatment of complexes 3 and 4 with NaOAr (Ar = &bond;C6H4-4-tBu) and (SiMe3)2NC(NPri)2Na in 1:4 and 1:2 molar ratios provided the corresponding aminophenoxy rare-earth metal derivatives {[ON](μ-OAr)Ln(μ-OAr)Na(THF)2}2 (Ln = Yb ( 7 ), Y ( 8 )) and {[ON]Ln[(iPrN)2CN(SiMe3)2]}2 (Ln = Yb ( 9 ), Y ( 10 )), respectively. These complexes were fully characterized, and their molecular structures were determined using single-crystal X-ray diffraction. Polymerization experiments showed that complexes 1 , 2 , 5 , 6 , 9 and 10 were highly active for the ring-opening polymerization of l -lactide in toluene, and complex 1 promoted l -lactide polymerization in a controlled fashion. The polymerization of rac-lactide initiated by the neutral aminophenoxy rare-earth metal complexes 5 , 6 , 9 and 10 in THF afforded heterotactic polymers. 相似文献
200.