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41.
Stamp collapse in soft lithography 总被引:1,自引:0,他引:1
Huang YY Zhou W Hsia KJ Menard E Park JU Rogers JA Alleyne AG 《Langmuir : the ACS journal of surfaces and colloids》2005,21(17):8058-8068
We have studied the so-called roof collapse in soft lithography. Roof collapse is due to the adhesion between the PDMS stamp and substrate, and it may affect the quality of soft lithography. Our analysis accounts for the interactions of multiple punches and the effect of elastic mismatch between the PDMS stamp and substrate. A scaling law among the stamp modulus, punch height and spacing, and work of adhesion between the stamp and substrate is established. Such a scaling law leads to a simple criterion against the unwanted roof collapse. The present study agrees well with the experimental data. 相似文献
42.
Robin D. Rogers Jerry L. Atwood Marvin D. Rausch David W. Macomber 《Journal of chemical crystallography》1990,20(6):555-560
The crystal structures of (
5-C5H4COMe)M(CO)3Me (M=Mo,W) have been determined. They are not isostructural. M=Mo isP21/c,a=10.205(6),b=14.192(8),c=8.135(6) Å,=93.43(4)° andD(calc)=1.71 g cm–3 forZ=4. M=WisP21/c,a=12.580(7),b=6.830(5),c=13.750(7) Å,=93.72(4)° andD(calc)=2.20 g cm–3 forZ=4. Both have a four-legged piano stool geometry with the substituted carbon making the closest M-C(
5) approach. The methyl group in the M=W derivative is disordered between twotrans-ligand positions. The average bonding parameters for the more accurately determined Mo analog are: Mo-C()5)=2.34(3) Å, Mo-CO=1.98(2) Å, Mo-Me=2.304(4) Å. 相似文献
43.
For part 29, see Rogerset al. (1989). 相似文献
44.
Richard A. Bunce David Rogers Takahiro Nago Scott A. Bryant 《Journal of heterocyclic chemistry》2008,45(2):547-550
Treatment of 2‐fluoro‐5‐nitrobenzyl bromide with active methylene compounds in the presence of excess potassium carbonate in acetone leads to the formation of highly functionalized 4H‐1‐benzopyrans by a tandem SN2‐SNAr reaction sequence. The reaction works well with β‐keto esters, β‐keto sulfones, β‐keto phosphine oxides, β‐keto phosphonates and β‐keto nitriles. The reaction is simple to perform and affords products in 50‐92% yields. 相似文献
45.
46.
Amaresh RR Lakshmikantham MV Baldwin JW Cava MP Metzger RM Rogers RD 《The Journal of organic chemistry》2002,67(8):2453-2458
3,4-Cyanomethyl substituted thiophenes reacted with thionyl chloride in the presence of base to give dicyano substituted thieno(3,4-c)thiophenes. The use of selenium oxychloride furnished the corresponding cyano substituted seleno(3,4-c)thiophene. 1,2-Phenylenediacetonitriles gave the corresponding cyano substituted benzo(c)thiophenes and benzo(c)selenenophenes, respectively, upon reaction with thionyl chloride and selenium oxychloride in the presence of base. 相似文献
47.
Rogers JE Slagle JE McLean DG Sutherland RL Brant MC Heinrichs J Jakubiak R Kannan R Tan LS Fleitz PA 《The journal of physical chemistry. A》2007,111(10):1899-1906
A comprehensive photophysical study of the linear and nonlinear absorption properties has been carried out on two series of two-photon absorbing dyes to gain insight into how structure-property relationships influence observed nonlinear absorption. The materials studied consist of an electron accepting benzothiazole group connected to an electron donating diphenylamine via a fluorene bridging group. Two series differ from each other by the addition of one phenyl group and for each series one-arm (dipolar, AF240 and AF270), two-arm (quadrupolar, AF287 and AF295), and three-arm (octupolar, AF350 and AF380) versions were studied. Overall the AF240 series exhibits higher intrinsic two-photon absorption (TPA) cross-sections than the AF270 series as well as enhanced nanosecond nonlinear absorption, with an increase with number of branches. The enhanced nanosecond nonlinearity is understood by taking into account the contribution from the singlet and triplet excited states and was verified by a two-photon assisted excited-state absorption model that satisfactorily predicts the nonlinear absorption of the chromophores. 相似文献
48.
Kim In S. Barrow Kevin D. Rogers Peter L. 《Applied biochemistry and biotechnology》2000,84(1-9):357-370
The fermentation characteristics and effects of lignocelulosic toxic compounds on recombinant Zymomonas mobilis ZM4(pZB5), which is capable of converting both glucose and xylose to ethanol, and its parental strain, ZM4, were characterized
using 13C and 31P nuclear magnetic resonance (NMR) in vivo. From the 31P NMR data, the levels of nucleoside triphosphates (NTP) of ZM(pZB5) using xylose were lower than those of glucose. This can
be related to the intrinsically slower assimilation and/or metabolism of xylose compared to glucose and is evidence of a less
energized state of ZM4(pZB5) cells during xylose fermentation. Acetic acid was shown to be strongly inhibitory to ZM4(pZB5)
on xylose medium, with xylose utilization being completely inhibited at pH 5.0 or lower in the presence of 10.9 g/L of sodium
acetate. From the 31P NMR results, the addition of sodium acetate caused decreased NTP and sugar phosphates, together with acidification of the
cytoplasm. Intracellular deenergization and acidification appear to be the major mechanisms by which acetic acid exerts its
toxic effects on this recombinant strain. 相似文献
49.
Different inner-sphere coordination environments are observed for the uranyl nitrate complexes formed with octyl-phenyl-N,N-diisobutylcarbamoylmethylphosphine oxide and tributyl phosphate in dodecane and in the hydrophobic ionic liquids (ILs) [C(4)mim][PF(6)] and [C(8)mim][N(SO(2)CF(3))(2)]. Qualitative differences in the coordination environment of the extracted uranyl species are implied by changes in peak intensity patterns and locations for uranyl UV-visible spectral bands when the solvent is changed. EXAFS data for uranyl complexes in dodecane solutions is consistent with hexagonal bipyramidal coordination and the existence of UO(2)(NO(3))(2)(CMPO)(2). In contrast, the complexes formed when uranyl is transferred from aqueous nitric acid solutions into the ILs exhibit an average equatorial coordination number of approximately 4.5. Liquid/liquid extraction results for uranyl in both ILs indicate a net stoichiometry of UO(2)(NO(3))(CMPO)(+). The concentration of the IL cation in the aqueous phase increases in proportion to the amount of UO(2)(NO(3))(CMPO)(+) in the IL phase, supporting a predominantly cation exchange mechanism for partitioning in the IL systems. 相似文献
50.
Biocatalysis has become an important method in the pharmaceutical industry for the incorporation of new functionality in small molecules. Currently this method is limited in the types of reactions that can be carried out and no strategy exists to systematically screen for new biocatalyzed reactions. This study involves the development of a medium throughput screen to identify and optimize new reactions using a series of marine-derived bacterial cell lines, which were screened against several (13)C labeled organic substrates. The reactions were analyzed using (13)C NMR as the primary screening tool. We describe the discovery of a bacterial catalyzed indole oxidation reaction in which complete conversion of (13)C labeled N-methyl indole to 3-hydroxyindole was observed. In addition, the sensitivity of this reaction to dO(2) levels can be exploited to oxidize to either 3-hydroxyindole or 2-oxoindole. This new platform sets up an important tool for the discovery of new organic transformations using an extensive library of marine bacteria. 相似文献