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51.
Science China Chemistry - 相似文献
52.
Wang Ruijie Zheng Jinyun Feng Xiangming Yao Ge Niu Huiting Liu Qingyi Chen Weihua 《Journal of Solid State Electrochemistry》2020,24(3):511-519
Journal of Solid State Electrochemistry - LiMnPO4 has been attracting attention for high energy density (701 Wh kg−1) and excellent safety. However, LiMnPO4 suffers from the... 相似文献
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Dr. Priyadarshi Chakraborty Yiming Tang Dr. Tom Guterman Zohar A. Arnon Yifei Yao Prof. Guanghong Wei Prof. Ehud Gazit 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23939-23947
Supramolecular polymer co-assembly is a useful approach to modulate peptide nanostructures. However, the co-assembly scenario where one of the peptide building blocks simultaneously forms a hydrogel is yet to be studied. Herein, we investigate the co-assembly formation of diphenylalanine (FF), and Fmoc-diphenylalanine (FmocFF) within the 3D network of FmocFF hydrogel. The overlapping peptide sequence between the two building blocks leads to their co-assembly within the gel state modulating the nature of the FF crystals. We observe the formation of branched microcrystalline aggregates with an atypical curvature, in contrast to the FF assemblies obtained from aqueous solution. Optical microscopy reveal the sigmoidal kinetic growth profile of these aggregates. Microfluidics and ToF-SIMS experiments exhibit the presence of co-assembled structures of FF and FmocFF in the crystalline aggregates. Molecular dynamics simulation was used to decipher the mechanism of co-assembly formation. 相似文献
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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
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Lirong Ma Xuanlin Yang Xiuzhong Yao Weiyu Weng 《Photochemistry and photobiology》2020,96(5):1088-1095
Hexyl aminolevulinate (HAL) is a lipophilic derivative of 5-aminolevulinic acid (5-ALA) and can induce more protoporphyrin IX (PpIX) formation and stronger fluorescence intensity (FI) than 5-ALA, which will greatly facilitate photodynamic diagnosis and therapy. The main drawback of HAL is its low solubility in neutral aqueous media. In this study, surfactants were used to increase HAL solubility in the cell culture medium and serum, followed by in vitro fluorescence formation measurement in human pancreatic cancer cells (SW1990) and in vivo fluorescence detection in tumor-bearing mice. The results showed that Tween 80 (TW80) and Kolliphor® HS 15 (HS15) increased the solubility of HAL in the selected media. Although TW80 and HS15 exhibited in vitro cytotoxicity at high concentrations (5 mg mL−1), they facilitated fluorescent signal formation at the early stage of cell incubation. When surfactants were used, the FI should be determined without the routine washing process because surfactant-containing culture medium caused the loss of synthesized PpIX during the washing process. When HAL dissolved in TW80 solution was injected intraperitoneally into pancreatic cancer-bearing mice at a dose of 50 mg kg−1, the tumors exhibited red fluorescence, which indicated that systemic administration of surfactant-solubilized HAL might be applicable for tumor fluorescence detection in vivo. 相似文献
57.
A series of novel diaroylhydrazone aluminum complexes have been synthesized and well-defined structurally, and their catalytic performance in the polymerization of ε-caprolactone and lactides have also been evaluated. Complexes [(L1–4)2AlMe] ( 1 – 4 ) {[L1 = (3,5-tBu2–2-OMe-C6H2)CH=NNCOC6H5], [L2 = (3,5-tBu2–2-OMe-C6H2)CH=NNCO(C6H4–4-OCH3)], [L3 = (3,5-tBu2–2-OMe-C6H2)CH=NNCO(C6H4–4-Br)] and [L4 = (2-OMe-C6H4)CH=NNCO(C6H4–4-tBu)]} were prepared through treatment of AlMe3 with the corresponding proligands L1–4H in molar ratios of 1: 1 or 1: 2. Chemical structures of all the complexes were well-defined by elemental analysis, NMR spectra as well as single-crystal X-ray study. Complexes [(L1–4)2AlMe] ( 1 – 4 ) in this work represent the first examples of aluminum complexes of aroylhydrazone ligands with crystallographic characterization. Specifically, they are all in monomeric form with a penta-coordinated aluminum center, including two approximately co-planar five-membered metallacycles with aluminum. Introduced bulky tert-butyl substituents in aroylhydrazone ligands could affect the geometry around the central metal which is a distorted square-based pyramid in complexes 1 – 3 while being a trigonal bipyramidal in complex 4 , thus affecting their catalytic behaviors. The complexes can successfully catalyze the ring-opening polymerization of ε-caprolactone and L-lactide under mild conditions without any activator. In addition, complexes 1 – 4 could also polymerize rac-lactide, affording atactic polylactides with high conversions and good controllability in relatively short reaction time. 相似文献
58.
Xiao-Ying Yu Jennifer Yao Edgar C. Buck Zihua Zhu 《Surface and interface analysis : SIA》2020,52(7):454-459
Trace analysis of nuclear materials in solid particles collected in the environment or particles in liquid slurry generated in nuclear material manufacturing processes can pinpoint elemental, organic, and isotopic signatures of nuclear fuel cycle activities and processes. Such information can support nuclear safeguards programs by increasing our ability to detect undeclared nuclear materials, routine activities for safeguarding at declared facilities, and illicit activities. However, trace radioactive material analysis in liquids and slurries is challenging using bulk approaches. For example, one drawback of sensitive analysis such as inductively coupled plasma mass spectrometry (ICP-MS) is that sample is consumed or destroyed as a result of the technical approach. We developed a vacuum compatible microfluidic interface to enable surface analysis of liquids and solid–liquid interactions using time-of-flight secondary ion mass spectrometry (ToF-SIMS). In this work, we illustrate the initial results from the analysis of liquid uranium oxide standard solutions using in situ liquid SIMS. Because the liquid SIMS analysis is almost nondestructive, the same sample can then be analyzed by other analytical techniques or saved for future reference. Consequently, multimodal analysis is possible. Our results demonstrate that in situ liquid SIMS can be used as a new approach to analyze radioactive materials in liquid and slurry forms of relevance to diverse applications. 相似文献
59.
The development of catalysts capable of catalyzing amidation of esters with amines to construct amides under mild conditions is of great importance. Compared to aliphatic amines, the direct catalytic amidation of esters with less nucleophilic aromatic amines is rather difficult. Employing simple lanthanide tris (amide) complexes Ln[N (SiMe3)2]3(μ-Cl)Li (THF)3 as the catalysts, it was found a broad range of aromatic amines and esters were efficiently converted into various amides in good yields under mild conditions. A plausible mechanism for this transformation was experimentally supported as starting from an amide exchange reaction between the lanthanide tris (amide) complex and the substrate amine. 相似文献
60.
Dr. Yongqi Yao Dr. Qifu Lin Dr. Wen Yang Prof. Dr. Weitao Yang Prof. Dr. Fenglong Gu Prof. Dr. Wei Guo Prof. Dr. Dingqiao Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(25):5607-5610
A cobalt(II)-catalyzed [4+2] annulation of picolinamides with alkynes via C−H bond activation has been developed. The operationally simple annulation reaction allows for the synthesis of acyl-substituted 1H-benzoquinoline bearing multiple aromatic rings (up to 96 % yield) without co-oxidant or other oxidation factors under mild conditions. Several control experiments were carried out. This practical [4+2] annulation provides an efficient route to access highly functionalized compounds. 相似文献