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941.
942.
Herein, we present the development of a far-infrared spectroscopic approach for studying metalloenzyme active sites in a redox-dependent manner. An electrochemical cell with 5 mm path and based on silicon windows was found to be appropriate for the measurement of aqueous solutions down to 200 cm(-1) . The cell was probed with the infrared redox signature of the metal-ligand vibrations of different iron-sulfur proteins. Each Fe-S cluster type was found to show a specific spectral signature. As a common feature, a downshift of the frequency of the Fe-S vibrations was seen upon reduction, in line with the increase of the Fe-S bond. This downshift was found to be fully reversible. Electrochemically induced FTIR difference spectroscopy in the far infrared is now possible, opening new perspectives on the understanding of metalloproteins in function of the redox state. 相似文献
943.
Vargas Jentzsch P Kampe B Rösch P Popp J 《The journal of physical chemistry. A》2011,115(22):5540-5546
Mg(2+), Na(+), and SO(4)(2-) are common ions in natural systems, and they are usually found in water bodies. Precipitation processes have great importance in environmental studies because they may be part of complex natural cycles; natural formation of atmospheric particulate matter is just one case. In this work, Na(2)Mg(SO(4))(2)·5H(2)O (konyaite), Na(6)Mg(SO(4))(4) (vanthoffite), and Na(12)Mg(7)(SO(4))(13)·15H(2)O (loeweite) were synthesized and their Raman spectra reported. By slow vaporization (at 20 °C and relative humidity of 60-70%), crystallization experiments were performed within small droplets (diameter ≤ 1-2 mm) of solutions containing MgSO(4) and Na(2)SO(4), and crystal formations were studied by Raman spectroscopy. Crystallization of Na(2)Mg(SO(4))(2)·4H(2)O (bloedite) was observed, and the formation of salt mixtures was confirmed by Raman spectra. Bloedite, konyaite, and loeweite, as well as Na(2)SO(4) and MgSO(4)·6H(2)O, were the components found to occur in different proportions. No crystallization of Na(6)Mg(SO(4))(4) (vanthoffite) was observed under the crystallization condition used in this study. 相似文献
944.
Gaitzsch J Appelhans D Gräfe D Schwille P Voit B 《Chemical communications (Cambridge, England)》2011,47(12):3466-3468
Crosslinkable and pH-sensitive amphiphilic block copolymers are promising candidates to establish pH-stable and permeable vesicles for synthetic biology. Here, we report the fabrication of crosslinked and pH-stable polymersomes as swellable vesicles for the pH-dependent loading and release of small dye molecules. 相似文献
945.
Petra Ahrweiler Nigel Gilbert Andreas Pyka 《Computational & Mathematical Organization Theory》2011,17(1):59-76
Modern knowledge-intensive economies are complex social systems where intertwining factors are responsible for the shaping
of emerging industries: the self-organising interaction patterns and strategies of the individual actors (an agency-oriented
pattern) and the institutional frameworks of different innovation systems (a structure-oriented pattern). In this paper, we
examine the relative primacy of the two patterns in the development of innovation networks, and find that both are important.
In order to investigate the relative significance of strategic decision making by innovation network actors and the roles
played by national institutional settings, we use an agent-based model of knowledge-intensive innovation networks, SKIN. We
experiment with the simulation of different actor strategies and different access conditions to capital in order to study
the resulting effects on innovation performance and size of the industry. Our analysis suggests that actors are able to compensate
for structural limitations through strategic collaborations. The implications for public policy are outlined. 相似文献
946.
Novel fused azecine ring systems were synthesized via the microwave-assisted thermal isomerization of terphenyl or biphenyl-pyridazine compounds possessing a vinyl and a tert-amino group, through application of a new extension of the tert-amino effect. Substrates for the ring closure were prepared from ortho-dihalobenzene or pyridazinone by consecutive Suzuki couplings with ortho-sec-amino- and formylphenylboronic acids, followed by Knoevenagel condensation of the aldehydes obtained. 相似文献
947.
Characteristics of iron(III) complexes with malic acid in 0.55 mol L?1 NaCl were investigated by voltammetric techniques. Three iron(III)‐malate redox processes were detected in the pH range from 4.5 to 11: first one at ?0.11 V, second at ?0.35 V and third at ?0.60 V. First process was reversible, so stability constants of iron(III) and iron(II) complexes were calculated: log K1(FeIII(mal))=12.66±0.33, log β2(FeIII(mal)2)=15.21±0.25, log K1(FeII(mal))=2.25±0.36, and log β2(FeII(mal)2)=3.18±0.32. In the case of second and third reduction process, conditional cumulative stability constants of the involved complexes were determined using the competition method: log β(Fe(mal)2(OH)x)=15.28±0.10 and log β(Fe(mal)2(OH)y)=27.20±0.09. 相似文献
948.
Petra Šulcová Lucie Vitásková Miroslav Trojan 《Journal of Thermal Analysis and Calorimetry》2010,99(2):409-413
Compounds based on CeO2 were synthesized as high-temperature environment-friendly inorganic pigments with interesting hues. The pigments have been
synthesized by using the solid state reaction in the temperature range from 1,300 to 1,600 °C. The host lattice of these pigments
is CeO2 that is doped by terbium ions. The incorporation of doped ions provides interesting orange colours after application into
ceramic glaze. The goal was to develop conditions for the synthesis of these compounds and to determine the influence of calcination
temperature on their colouring effects. The simultaneous TG-DTA measurements were used for determination of the temperature
region of the pigment formation and thermal stability of pigments. The pigments were also evaluated from the standpoint of
their structure and particle sizes. 相似文献
949.
950.
Hana Brozmanová Ilona Peřinová Petra Halvová Milan Grundmann 《Journal of separation science》2010,33(15):2287-2293
A LC‐MS/MS method was developed and validated for the determination of cyclosporine A (CsA) and its three phase 1 metabolites AM1, AM9, and AM4N in whole blood and lymphocytes isolated on the Histopaque gradient. 200 μL of whole blood was precipitated with 10 mol/L zinc sulfate in acetonitrile/methanol (40:60, v/v) and lymphocytes isolated from 1.5 mL blood were extracted with acetonitrile/methanol (40:60, v/v). The analytes and internal standard cyclosporine D were separated on RP column BEH C18, 2.1×50 mm, 1.7 μm using gradient LC‐MS/MS analysis in positive electrospray mode. Time of analysis was 5 min. Linearity in blood was 5–2000 μg/L for CsA, AM1, and AM9; 2–500 μg/L for AM4N; and 2–500 μg/L for all substances in lymphocytes. Coefficient of variations was 1.8–9.8% and recovery was 92.0–110.0%. The method was used in early and chronic renal transplant patients for therapeutic drug monitoring of CsA to compare either its share in lymphocytes as target organ or binding to one lymphocyte. The same parameters were calculated for all metabolites tested. 相似文献