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101.
Dattilo D Armelao L Maggini M Fois G Mistura G 《Langmuir : the ACS journal of surfaces and colloids》2006,22(21):8764-8769
We report the immobilization of a fulleropyrrolidine, bearing a dec-9-ynyl functionality, on silicon surfaces through a thermal hydrosilylation protocol. Contact angle measurements on porous silicon (PS) surfaces reveal an unusual dependence of the angle with the PS roughness that apparently contradicts Wenzel's formula. This result has been explained by an extension of Wenzel's model in which the critical angle, which discriminates between the hydrophilic/hydrophobic character of a solid material, is substantially reduced below 90 degrees by surface roughness. 相似文献
102.
Benedetti M Fanizzi FP Maresca L Natile G 《Chemical communications (Cambridge, England)》2006,(10):1118-1120
Zeise's anion in strongly basic hydroxylated solvents undergoes unprecedented nucleophilic addition of OR- (R = H, Me, Et) to the eta2-ethene giving trans-[PtCl2(eta1-C2H4OR)(OR)]2- which readily reacts with bidentate nitrogen donors N-N to give Cl- and OR- substitution and formation of [PtCl(CH2CH2OR)(N-N)]. Protonolysis of this stable organometallic species offers a versatile route to cationic [PtCl(eta2-C2H4)(N-N)]+ complexes. 相似文献
103.
Giovanni Zocchi 《Chemphyschem》2006,7(3):555-560
One common strategy for the detection of biomolecules is labeling either the target itself or an antibody that binds to it. Herein, a different approach, based on detecting the conformational change of a probe molecule induced by binding of the target is discussed. That is, what is being detected is not the presence of the target or the probe, but the conformational change of the probe. Recently, a single-molecule sensor has been developed that exploits this mechanism to detect hybridization of a single DNA oligomer to a DNA probe, as well as specific binding of a single protein to a DNA probe. Biomolecular recognition often involves large conformational changes of the molecules involved, and therefore this strategy may be applicable to other assays. 相似文献
104.
Molecular modeling techniques have been used to investigate the interaction of L-lysine in aqueous medium with silanol and methyl sites onto quartz substrates. The substrate effect has been studied for partially hydrophilic surfaces formed by silanol and methyl groups with a ratio of 1:5 and hydrophobic fully methylated surfaces. Molecular dynamics and static calculations indicate that L-lysine does not show any significant interaction with fully methylated surfaces, while its interaction with hydroxylated/methylated surfaces is dominated by electrostatic and H-bond terms. Accordingly, on fully methylated surfaces there is no preferential orientation of L-lysine with respect to the surface, while for hydroxylated/methylated surfaces the L-lysine-surface interaction mainly depends on the molecular orientation, with a preferred geometry involving the ammonium group pointing toward the silanol site. The structure of water shells around L-lysine molecules was shown to be strongly affected by the relative hydrophilic/hydrophobic character of the surfaces. In particular, the order is almost completely lost for partially hydrophilic surfaces, while well-defined hydration shells around L-lysine are obtained for hydrophobic surfaces. 相似文献
105.
106.
Köhler J Hemberger P Fischer I Piani G Poisson L 《The journal of physical chemistry. A》2011,115(50):14249-14253
The ultrafast dynamics of isolated 9-fluorenone was studied by femtosecond time-resolved photoionization and photoelectron spectroscopy. The molecule was excited around 264-266 nm into the S(6) state. The experimental results indicate that the excitation is followed by a multistep deactivation. A time constant of 50 fs or less corresponds to a fast redistribution of energy within the initially excited manifold of states, i.e., a motion away from the Franck-Condon region. Internal conversion to the S(1) state then proceeds within 0.4 ps. The S(1) state is long-lived, and only a lower bound of 20 ps can be derived. In addition, we computed excited state energies and oscillator strengths by TD-DFT theory, supporting the interpretation of the experimental data. 相似文献
107.
Castellano M Fortea-Pérez FR Stiriba SE Julve M Lloret F Armentano D De Munno G Ruiz-García R Cano J 《Inorganic chemistry》2011,50(22):11279-11281
Self-assembly of the rigid rodlike ligand N,N'-4,4'-diphenylethynebis(oxamate) (dpeba) and Cu(2+) ions affords a novel dinuclear copper(II) metallacyclophane (nBu(4)N)(4)[Cu(2)(dpeba)(2)]·4MeOH·2Et(2)O (1) featuring a very long intermetallic distance (r = 15.0 ?). Magnetic susceptibility measurements for 1 reveal a moderately weak but nonnegligible intramolecular antiferromagnetic coupling between the two metal centers across the double para-substituted diphenylethynediamidate bridge (J = -3.9 cm(-1); H = -JS(1)S(2), where S(1) = S(2) = S(Cu) = (1)/(2)). Density functional electronic structure calculations on 1 support the occurrence of a spin polarization mechanism. 相似文献
108.
Structural studies on Ba(II) adducts of the cytosine nucleobase and its derivative 1-Methylcytosine*
AbstractThe use of the cytosine nucleobase or its 1-Methylcytosine derivative as ligands toward barium(II) cations led to the formation of three compounds, {[Ba(1-Mecyt)(H2O)X2]}n [X=Cl (1), Br (2)], and {[Ba(cyt)2(H2O)(ClO4)2]}n (3). Depending on the ligand and the counterion employed, 1–3 exhibit different architectures, which serve as a playground to study how the methyl substitution, together with the nature of the counterion are both significant in the self-assembling process of such species. The effect of the nature and size of the alkaline-earth metal ion on the final structural motif is also evident when comparing these structures with parent complexes of the Ca(II) ion. 相似文献
109.
Bidyut B. Sarma Jonglack Kim Jonas Amsler Giovanni Agostini Claudia Weidenthaler Norbert Pfnder Raul Arenal Patricia Concepcin Philipp Plessow Felix Studt Gonzalo Prieto 《Angewandte Chemie (International ed. in English)》2020,59(14):5806-5815
Realizing the full potential of oxide‐supported single‐atom metal catalysts (SACs) is key to successfully bridge the gap between the fields of homogeneous and heterogeneous catalysis. Here we show that the one‐pot combination of Ru1/CeO2 and Rh1/CeO2 SACs enables a highly selective olefin isomerization‐hydrosilylation tandem process, hitherto restricted to molecular catalysts in solution. Individually, monoatomic Ru and Rh sites show a remarkable reaction specificity for olefin double‐bond migration and anti‐Markovnikov α‐olefin hydrosilylation, respectively. First‐principles DFT calculations ascribe such selectivity to differences in the binding strength of the olefin substrate to the monoatomic metal centers. The single‐pot cooperation of the two SACs allows the production of terminal organosilane compounds with high regio‐selectivity (>95 %) even from industrially‐relevant complex mixtures of terminal and internal olefins, alongside a straightforward catalyst recycling and reuse. These results demonstrate the significance of oxide‐supported single‐atom metal catalysts in tandem catalytic reactions, which are central for the intensification of chemical processes. 相似文献
110.
Attilio Naccarato Sacha Moretti Giovanni Sindona Antonio Tagarelli 《Analytical and bioanalytical chemistry》2013,405(25):8267-8276
A new analytical approach, using paper spray tandem mass spectrometry, has been developed for assay of carnitine and acylcarnitines in urine. Paper spray (PS) is a very promising technique, especially in clinical investigations, because of its simplicity, low cost, and rapid sample preparation. A home-made paper spray device was used for assay of urinary acylcarnitines (C2–C18). The performance of solvents with different elution efficiency and paper substrates with different porosity grade and structure were tested by use of spiked synthetic urine. Tandem mass spectrometry in multiple reaction monitoring (MRM) mode was optimized to obtain better specificity and sensitivity. Analyte signals were evaluated for stability and reproducibility. Calibration with [2H3]propionylcarnitine (C3-d3), [2H3]octanoylcarnitine (C8-d3), and [2H3] palmitoylcarnitine (C16-d3) as internal standards was used for quantification. Very good linearity was obtained, with correlation coefficients >0.99 for C0–C12 and C16 acylcarnitines and >0.96 for C14 and C18 acylcarnitines. Accuracy and precision (RSD, %) of the proposed procedure were tested at concentrations of 0.8, 8, and 20 mg L?1 with very satisfactory results: overall mean accuracy was 98.9 % and overall mean relative standard deviation 1 %. Limits of detection (LOD) between 6 and 208 μg L?1 for propionylcarnitine and tetradecanoylcarnitine, respectively, can be regarded as very satisfactory. Application of the method to real urine proved that paper spray tandem mass spectrometry is a simple, rapid, and direct tool (no derivatization is required) for assay of carnitine and C2–C12 acylcarnitines in urine. 相似文献