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971.
972.
Octahedral Chiral‐at‐Metal Iridium Catalysts: Versatile Chiral Lewis Acids for Asymmetric Conjugate Additions
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Xiaodong Shen Haohua Huo Chuanyong Wang Bo Zhang Dr. Klaus Harms Prof. Dr. Eric Meggers 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9720-9726
Octahedral iridium(III) complexes containing two bidentate cyclometalating 5‐tert‐butyl‐2‐phenylbenzoxazole ( IrO ) or 5‐tert‐butyl‐2‐phenylbenzothiazole ( IrS ) ligands in addition to two labile acetonitrile ligands are demonstrated to constitute a highly versatile class of asymmetric Lewis acid catalysts. These complexes feature the metal center as the exclusive source of chirality and serve as effective asymmetric catalysts (0.5–5.0 mol % catalyst loading) for a variety of reactions with α,β‐unsaturated carbonyl compounds, namely Friedel–Crafts alkylations (94–99 % ee), Michael additions with CH‐acidic compounds (81–97 % ee), and a variety of cycloadditions (92–99 % ee with high d.r.). Mechanistic investigations and crystal structures of an iridium‐coordinated substrates and iridium‐coordinated products are consistent with a mechanistic picture in which the α,β‐unsaturated carbonyl compounds are activated by two‐point binding (bidentate coordination) to the chiral Lewis acid. 相似文献
973.
Li Chenglang Dou Qiang Bai Zhifei Lu Quliang 《Journal of Thermal Analysis and Calorimetry》2015,122(1):407-417
Journal of Thermal Analysis and Calorimetry - The effect of cadmium phenylmalonate (PMA-Cd) as a novel nucleating agent on the crystallization behaviors and spherulitic morphology of poly(lactic... 相似文献
974.
Tao Jia Weilong Zhou Fenghong Li Yajun Gao Lu Wang Jianxiong Han Jingying Zhang Yue Wang 《中国科学:化学(英文版)》2015,(2):323-330
Three alcohol/water-soluble porphyrins,Zn-TPy PMe I:zinc(II)meso-tetra(N-methyl-4-pyridyl)porphyrin tetra-iodide,ZnTPy PAd Br:zinc(II)meso-tetra[1-(1-adamantylmethyl ketone)-4-pyridyl]porphyrin tetra-bromide and Mn Cl-TPy PAd Br:manganese(III)meso-tetra[1-(1-adamantylmethyl ketone)-4-pyridyl]porphyrin tetra-bromide were employed as cathode interlayers to fabricate polymer solar cells(PSCs).The PC71BM([6,6]-phenyl C71 butyric acid methyl ester)and PCDTBT(poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)])-blend films were used as active layers in polymer solar cells(PSCs).The PSCs with alcohol/water-soluble porphyrins interlayer showed obviously higher power conversion efficiency(PCE)than those without interlayers.The highest PCE,6.86%,was achieved for the device with Mn ClTPy PAd Br as an interlayer.Ultraviolet photoemission spectroscopic(UPS),carrier mobility,atomic force microscopy(AFM)and contact angle( )characterizations demonstrated that the porphyrin molecules can result in the formation of interfacial dipole layer between active layer and cathode.The interfacial dipole layer can obviously improve the open-circuit voltage(Voc)and charge extraction,and sequentially lead to the increase of PCE. 相似文献
975.
976.
In Situ Synthesis and Characterization of Poly(aryleneethynylene)‐Grafted Reduced Graphene Oxide
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Sai Sun Dr. Xiaodong Zhuang Prof. Dr. Bo Liu Luxing Wang Linfeng Gu Prof. Dr. Sannian Song Prof. Dr. Bin Zhang Prof. Dr. Yu Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2247-2252
Using highly soluble bromo‐functionalized reduced graphene oxide (RGBr) as a key graphene template for surface‐directing Sonogashira–Hagihara polymerization, a novel soluble poly(arylene‐ethynylene)‐grafted reduced graphene oxide, hereafter abbreviated as PAE‐g‐RGO, was prepared in situ. The entirely different electron distribution of LUMO and HOMO of PAE‐g‐RGO suggested the existence of a charge‐transfer (CT) state (PAE.?–RGO.+). The negative ΔGCS value (?2.57 eV) indicates that the occurrence of the charge separation via 1RGO* in o‐DCB is exothermic and favorable. Upon irradiation with 365 nm light, the light‐induced electron paramagnetic resonance (LEPR) spectrum of PAE‐g‐RGO showed a decrease in the spin‐state density owing to photoinduced intramolecular electron transfer events in this system. A sandwich‐type Al/PAE‐g‐RGO/ITO device showed representative bistable electrical switching behavior. The nonvolatile memory performance was attributed to the CT‐induced conductance changes, which was supported by molecular computation results and conductive atomic force microscopy (C‐AFM) images. 相似文献
977.
Dr. Kai Wu Ya-Jun Hou Yu-Lin Lu Yan-Zhong Fan Ya-Nan Fan Dr. Hui-Juan Yu Dr. Kang Li Prof. Dr. Mei Pan Prof. Dr. Cheng-Yong Su 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11903-11909
Molecular or supramolecular level photoluminescence (PL) modulation combining chemical and photonic input/output signals together in an integrated system can provide potential high-density data memorizing and process functions intended for miniaturized devices and machines. Herein, a PL-responsive supramolecular coordination cage has been demonstrated for complex interactions with redox-active guests. PL signals of the cage can be switched and modulated by adding or retracting Fc derivatives or converting TTF into different oxidation states through chemical or photochemical pathways. As a result, reversible or stepwise PL responses are displayed by these host–guest systems because of the occurrence of photoinduced electron-transfer (PET) or fluorescence resonance energy transfer (FREnT) processes, providing unique nanodevice models bearing off/on logic gates or memristor-like sequential memory and Boolean operation functions. 相似文献
978.
Meiru Lu Dr. Xiaoling Wu Dr. Changlong Hao Prof. Chuanlai Xu Prof. Hua Kuang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(28):7023-7030
Nonylphenols (NPNs) are persistent endocrine disruptors and their release into the environment is causing increasing concern about their impact on human health. Herein, an ultrasensitive electrochemical immunosensor was developed for the detection of NPNs in the leachates from 61 instant noodle containers (INCs) from 8 countries across Southeast Asia. Gold nanoclusters (AuNCs) were self-assembled with reduced graphene oxide (rGO; polyethylenimine–rGO) and used to modify a glassy carbon electrode (GCE), which showed excellent electrical conductivity. An anti-NPN antibody was then immobilized on the AuNCs and, if it specifically bound NPN, the reduction in conductivity of the GCE was remarkable. The designed immunosensor has a low detection limit (5.25 ng L−1) and high sensitivity for NPNs in the leachates of INCs. Remarkably, the leaching of estrogen-like compounds from different plastics of INCs and the correlation between NPN content and total estrogenic activity were thoroughly investigated. High temperatures caused polyethylene and polystyrene INCs to release more estrogen-like compounds than that of polypropylene INCs; this increased release of NPNs was associated with higher estrogen activity in living cells. These data fill the gap in human and environmental exposure to estrogen-like compounds through INCs. 相似文献
979.
980.
在超临界水反应器中,硫酸钠是易造成堵塞的一种常见无机盐,研究其结晶动力学对于防盐沉积反应器的设计具有重要意义.本文采用LAMMPS分子动力学模拟软件研究硫酸钠在超临界水中的微观结晶过程,其中水分子采用SPC/E模型,离子-离子、离子-水分子相互作用采用Coulumb和Lennard-Jones联合势能函数.结果表明:水对离子的静电屏蔽作用随温度升高而增强、随密度减小而减弱;增大超临界水的温度和密度有利于离子扩散,进而促进离子相互碰撞、成核;在模拟的超临界水参数范围内,其成核速率的数量级为1029cm-3·s-1,生长速率为(19.8~25.8) m·s-1. 相似文献