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991.
Capillary electrophoresis dynamic reaction cell™ inductively coupled plasma mass spectrometry (CE-DRC-ICP-MS) for the determination of sulfur-containing amino acids is described. The sulfur-containing amino acids studied include l-cysteine, l-cystine, dl-homocystine and l-methionine. The species studied were well separated using a 70 cm length×75 μm i.d. fused silica capillary while the applied voltage was set at +22 kV and a 10 mmol l−1 disodium tetraborate buffer (pH 9.8) containing 0.1 mmol l−1 EDTA and 0.5 mmol l−1 Triton X-100 was used as the electrophoretic buffer. The sulfur-selective electropherogram was determined at m/z 48 as by using its reaction with O2 in the reaction cell. The method avoided the effect of polyatomic isobaric interferences at m/z 32 caused by and on by detecting as the oxide ion at m/z 48, which is less interfered. The detection limit of various species studied was in the range of 0.047-0.058 μg S ml−1, which corresponded to the absolute detection limit of 1.3-1.6 pg S based on the injection volume of 27 nl. We determined the concentrations of selected sulfur-containing amino acids in urine and nutritive complement samples. The recovery was in the range of 92-128% for various species. 相似文献
992.
We reported the design and synthesis of a new type of metal-cation probes, 3-hydroxy-4-(1,4,7,10-tetraoxa-13-azacyclopentadec-13-ylmethyl)naphthalene-2-carbaldehyde (1a) and its single hydrogen-bond analogue 1-(1,4,7,10-tetraoxa-13-azacylopentadec-13-ylmethyl)-2-naphthol (2a), in which 1-aza-15-crown-5 ether in combination with the naphthol oxygen acts as a receptor, while the mechanism of excited-state intramolecular proton transfer (ESIPT) is exploited as a signal transducer. The association constant of (2.5±0.5)×104, (3.8±0.4)×104, (5.5±0.5)×103 and (1.2±0.3)×104 M−1 for the formation of 1a/Na+, 1a/Ca2+, 2a/Na+ and 2a/Ca2+ complexes, respectively, in CH3CN plus drastic fluorescence changes due to the fine-tuning of ESIPT reaction upon complexation, lead 1a and 2a to be highly sensitive fluorescent sensors. The results add a new class into the category of metal-cation probes, with the perspective of designing ESIPT systems capable of sensing bio-analytes. 相似文献
993.
Yi-Liang Lin Po-Yen Wang Ling-Ling Hsieh Kuan-Hsuan Ku Yun-Tai Yeh Chien-Hou Wu 《Journal of chromatography. A》2009,1216(36):6377-6381
A simple and sensitive method is described for the determination of picomolar amounts of C1–C9 linear aliphatic aldehydes in waters containing heavy metal ions. In this method, aldehydes were first derivatized with 2,4-dinitrophenylhydrazine (DNPH) at optimized pH 1.8 for 30 min and analyzed by HPLC with UV detector at 365 nm. Factors affecting the derivatization reaction of aldehydes and DNPH were investigated. Cupric ion, an example of heavy metals, is a common oxidative reagent, which may oxidize DNPH and greatly interfere with the determination of aldehydes. EDTA was used to effectively mask the interferences by heavy metal ions. The method detection limits for direct injection of derivatized most aldehydes except formaldehyde were of the order of 7–28 nM. The detection limit can be further lowered by using off-line C18 adsorption cartridge enrichment. The recoveries of C1–C9 aldehydes were 93–115% with a relative standard deviation of 3.6–8.1% at the 0.1 μM level for aldehydes. The HPLC–DNPH method has been applied for determining aldehyde photoproducts from Cu(II)–amino acid complex systems. 相似文献
994.
Wen‐Shuo Kuo Shiaw‐Min Hwang Hei‐Tin Sei Yu‐Cian Ku Lee‐Feng Hsu Fong‐Yu Cheng Patrick Ching‐Ho Hsieh Chen‐Sheng Yeh 《中国化学会会志》2009,56(5):940-948
We report that human mesenchymal stem cells (hMSCs) were successfully labeled with poly(lactide‐co‐glycolide) nanoparticles (PLGA NPs) surface‐conjugated quantum dots (QDs) (PLGA‐QD NPs) via endocytosis pathway. These NPs were not toxicity even treated with PLGA‐QD NPs at high concentrations for at least four weeks. Besides, PLGA‐QD NPs‐labeled hMSCs did not change their proliferation and differentiation capability toward the cell fates of adipocytes, osteocytes, and chrondrocytes. It's known that PLGA has been widely employed to act as delivery carrier which encapsulates drugs and releases them under a controlled way. Currently, we have also demonstrated that FITC‐loaded PLGA‐QD NPs degraded in hMSCs to achieve intracellular release of FITC. The aim of this research is to investigate viability, proliferation and differentiation capability and the potential for gene delivery of MSCs labeled with PLGA‐QD NPs. In addition to PLGA‐QD NPs, QDs alone were used to serve as a control set for comparison. 相似文献
995.
Reaction of Mo(CO)(η2‐C2Ph2)2(η4‐C4Ph4) and Me3NO in acetonitrile solvent affords Mo(NCMe)(η2‐C2Ph2)2(η4‐C4Ph4) 1 . Compound 1 reacts with trimethylphosphine to produce Mo(PMe3)(η2‐C2Ph2)2(η4‐C4Ph4) 2 , or reacts with diphenylacetylene to produce (η5‐C5Ph5)2Mo 3 and Mo(η2‐O2CPh)(η4‐C4Ph4H)(η4‐C4Ph4) 4 . The molecular structures of 1, 2 and 4 have been determined by an X‐ray diffraction study. 相似文献
996.
α‐Imidazolformylarylhydrazine 2 and α‐[1,2,4]triazolformylarylhydrazine 3 have been synthesized through the nucleophilic substitution reaction of 1 with imidazole and 1,2,4‐triazole, respectively. 2,2′‐Diaryl‐2H,2′H‐[4,4′]bi[[1,2,4]‐triazolyl]‐3,3′‐dione 4 was obtained from the cycloaddition of α‐chloroformylarylhydrazine hydrochloride 1 with 1,2,4‐triazole at 60 °C and in absence of n‐Bu3N. The inducing factor for cycloaddition of 1 with 1,2,4‐triazole was ascertained as hydrogen ion by the formation of 4 from the reaction of 3 with hydrochloric acid. 4 was also acquired from the reaction of 3 with 1 and this could confirm the reaction route for cycloaddition of 1 with 1,2,4‐triazole. Some acylation reagents were applied to induce the cyclization reaction of 2 and 3.1 possessing chloroformyl group could induce the cyclization of 2 to give 2‐aryl‐4‐(2‐aryl‐4‐vinyl‐semicarbazide‐4‐yl)‐2,4‐dihydro‐[1,2,4]‐triazol‐3‐one 6. 7 was obtained from the cyclization of 2 induced by some acyl chlorides. Acetic acid anhydride like acetyl chloride also could react with 2 to produce 7D . 5‐Substituted‐3‐aryl‐3H‐[1,3,4]oxadiazol‐2‐one 8 was produced from the cyclization reaction of 3 induced by some acyl chlorides or acetic acid anhydride. The 1,2,4‐triazole group of 3 played a role as a leaving group in the course of cyclization reaction. This was confirmed by the same product 8 which was acquired from the reaction of 1 , possessing a better leaving group: Cl, with some acyl chlorides or acetic acid anhydride. 相似文献
997.
998.
Kuo CK Chang JC Yeh CY Lee GH Wang CC Peng SM 《Dalton transactions (Cambridge, England : 2003)》2005,(22):3696-3701
A series of triruthenium complexes with arylacetylide axial ligands Ru(3)(dpa)(4)(C(2)X)(2)(BF(4))(y)(dpa = dipyridylamido; X = Fc, y= 0 (1); X = Ph, y= 0 (2); X = PhOCH(3), y= 1 (3); X = PhC(5)H(11), y= 1 (4); X = PhCN, y= 0 (5); X = PhNO(2), y= 0 (6)) have been synthesized. The crystal structures show that the Ru-Ru bond lengths (2.3304(9)-2.3572(5)A) of these compounds are longer than those of Ru(3)(dpa)(4)Cl(2)(Ru-Ru=2.2537(1)A). This is ascribed to the formation of the stronger pi-backbonding from metal to axial ligand which weakens the Ru-Ru interactions and the bond order is reduced in the triruthenium unit. Cyclic voltammetry and differential pulse voltammetry show that compound exhibits electronic coupling between the two ferrocenyl units with DeltaE(1/2) close to 100 mV. Compounds 2-6 display three triruthenium-based reversible one-electron redox couples, two oxidations and one reduction, and the electrode potentials shift upon varying the substituents. A linear relationship is observed when the Hammett constants are plotted against the redox potentials. 相似文献
999.
The synthesis and structures of a mononuclear copper(I) carbonyl complex [Cu(OClO3)(CO)(H2CPz2')] (3) and a dinuclear copper(I) carbonyl complex [{Cu(CO)(H2CPz2')}2(mu-pyrazine)](ClO4)2 (4), where H2CPz2' = bis(3,5-dimethylpyrazol-1-yl)methane, are described. These two compounds were generated by the carbonylation of the corresponding copper(I)-acetonitrile complexes, [Cu(H2CPz2')(MeCN)](ClO4) (1) and [{Cu(H2CPz2')(MeCN)}2(mu-pyrazine)](ClO4)2 (2). Alternatively, treatment of mononuclear 1 and 3, respectively, with pyrazine in a molar ratio of 2:1 produces the pyrazine-bridged dinuclear Cu(I) complexes 2 and 4. Each of the complexes 1-4 can react with PPh3 to generate a common three-coordinated copper(I) complex [Cu(PPh3)(H2CPz2')](ClO4) (5). The structures of complexes 1-5 were all confirmed by X-ray crystallography. Comparison of the Cu(I)-C(CO) bond distances and the CO stretching frequencies of 3 and 4 indicates the back-donating properties of d pi(Cu)-pi*(pyrazine) bonds in 4, and accordingly, stabilizes the mixed-valence species generated from 2. Complex 3, stabilized by the strong interaction between copper(I) ion and perchlorate counteranion (Cu(I)-O(ClO4) = 2.240(3) A), is a potential precursor for polynuclear copper(I) carbonyl complexes. 相似文献
1000.
A new type of human calicivirus (HuCV) showing the classic cup-shaped surface morphology was identified in the stool sample from a child with symptoms of acute gastroenteritis in Seoul, Korea (SK virus). Genomic RNA was extracted directly from the stool sample, and the nucleotide sequence of 3.2 kb of the 3' end of SK virus was determined from cDNA. This region spanned sequences from the RNA-dependent RNA polymerase (RDRP) region in the open reading frame 1 (ORF1) to the 3' poly A tail. The non-structural and capsid protein coding sequences were fused in a single ORF as observed in Manchester type (Genogroup III). However, ORF2 of Manchester virus was missing in SK virus. In RDRP region, SK virus showed amino acid and nucleotide identities of 74-75% and 68-69% respectively, with those of Manchester virus, while showed 34-46% and 55-60% identities respectively with those of other human caliciviruses. However, capsid protein of SK virus showed a partial (29-46%) amino acid identity with those of other caliciviruses including Manchester type. The closest resemblance in amino acid (97-99%) and nucleotide sequence (85-86%) identities were found in RDRP region with Vanderbijlpark and Pretoria isolates recently found in South Africa. These results suggest that SK virus together with Vanderbijlpark and Pretoria isolates belong to a new type different from Manchester virus. 相似文献