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61.
Silanylidene and Germanylidene Anions: Valence‐Isoelectronic Species to the Well‐Studied Phosphinidene 下载免费PDF全文
Dr. Mujahuddin M. Siddiqui Dr. Soumen Sinhababu Sayan Dutta Dr. Subrata Kundu Paul Niklas Ruth Annika Münch Dr. Regine Herbst‐Irmer Prof. Dietmar Stalke Dr. Debasis Koley Prof. Herbert W. Roesky 《Angewandte Chemie (International ed. in English)》2018,57(36):11776-11780
The reduction of TipMCl3 (Tip=2,4,6‐triisopropylphenyl) (M=Si, Ge) with KC8 in the presence of cyclic alkyl(amino) carbene (cAAC) afforded the acyclic silanylidene and germanylidene anions in the form of potassium salt [K(cAAC)MTip]2 (M=Si ( 1 ); Ge ( 2 )). The silanylidene and germanylidene anions are valence‐isoelectronic to the well‐studied phosphinidene and are a new class of acyclic anions of Group 14. Compounds 1 and 2 were isolated and well characterized by NMR and single‐crystal X‐ray structure analysis. Furthermore, the structure and bonding of compounds 1 and 2 was investigated by computational methods. 相似文献
62.
G. Daikuhara E. Truog L. Michaelis L. T. Sharp D. R. Hoogland H. A. Noyes O. Arrhenius C. B. Lipman H. R. Christensen F. W. Parker H. Kappen A. Densch A. Rippel Th. Arnd O. Schreiner G. Loges E. Ramann F. K. Cameron R. Ulbricht W. Wolf W. Jani Biéler-Chatelan E. A. Mitscherlich C. W. Davis B. S. Davisson H. Neubauer W. Schneider Fr. Czapek G. Wunder J. K. Greisenegger K. Vorbuchner H. Niklas Hirschberger Ausschuss für Boden und Düngung des Verbandes Landwirtschaftlicher Versuchs-Stationen im Deutschen Reiche 《Analytical and bioanalytical chemistry》1924,65(6-7):273-274
63.
A. Gehring S. Goy P. Müller O. Roos Br. Tacke Th. Arnd J. von Csiky G. von Eperjessy H. Kappen R. A. Kutschinsky S. T. Jensen St Kühn S. N. Aleschin O. Lemmermann J. König J. Hasenbäumer A. A. J. v. 'Sigmond A. Němec H. Neubauer L. Dworak K. Hesse M. Gračanin Hempelmann L. Fresenius H. Fischer E. Blanck W. Jessen W. Lesch E. Hoffmann B. Dirks F. Scheffer E. Becker R. Balks H. Elleder M. Gerlach Th. Römer A. Densch E. A. Mitscherlich H. Vageler R. Meyer H. Opitz K. H. Rathsack H. Niklas H. Poschenrieder J. Trischler J. Lanik Anna Koppová O. Wehrmann O. Eckstein A. Jacob G. N. Hoffer 《Analytical and bioanalytical chemistry》1932,90(11-12):456-480
64.
Frisk T Sandström N Eng L van der Wijngaart W Månsson P Stemme G 《Lab on a chip》2008,8(10):1648-1657
We present the design, fabrication and successful testing of a 14x14x4 mm3 integrated electronic narcotics sensing system which consists of only four parts. The microsystem absorbs airborne narcotics molecules and performs a liquid assay using an integrated quartz crystal microbalance (QCM). A vertically conductive double-sided adhesive foil (VCAF) was used and studied as a novel material for LOC and MEMS applications and provides easy assembly, electrical contacting and liquid containment. The system was tested for measuring cocaine and ecstasy, with successful detection of amounts as small as 100 ng and 200 ng, respectively. These levels are of interest in security activities in customs, prisons and by the police. 相似文献
65.
Rasitha Manha Veedu Niklas Niemeyer Dr. Nils Bäumer Dr. Krishnan Kartha Kalathil Prof. Dr. Johannes Neugebauer Prof. Dr. Gustavo Fernández 《Angewandte Chemie (International ed. in English)》2023,62(49):e202314211
The functionalization of π-conjugated scaffolds with sterically demanding substituents is a widely used tactic to suppress cofacial (H-type) stacking interactions, which may even inhibit self-assembly. Contrary to expectations, we demonstrate herein that increasing steric effects can result in an enhanced thermodynamic stability of H-type supramolecular polymers. In our approach, we have investigated two boron dipyrromethene (BODIPY) dyes with bulky phenyl ( 2 ) and mesityl ( 3 ) meso-substituents and compared their self-assembly in nonpolar media with that of a parent meso-methyl BODIPY 1 lacking bulky groups. While the enhanced steric demand induces pathway complexity, the superior thermodynamic stability of the H-type pathways can be rationalized in terms of additional enthalpic gain arising from intermolecular C−H⋅⋅⋅F−B interactions of the orthogonally arranged aromatic substituents, which overrule their inherent steric demand. Our findings underline the importance of balancing competing non-covalent interactions in self-assembly. 相似文献
66.
67.
The amino acid derivative Boc-Asp-OBzl (Boc=N-butyloxycarbonyl; Asp=aspartic acid; Bzl=benzyl) was functionalized by coupling its carboxylate side chain to dipicolylamine. This yielded the tridentate nitrogen donor ligand Boc-Asp(Dpa)-OBzl (-OBzl). The compound -OBzl contains three different carbonyl groups: a tertiary amide linkage between Asp and Dpa, a C-terminal benzyl ester function, and an N-terminal urethane protecting group. NMR spectra were used to compare the reactivity of these moieties. The Boc protecting group gives rise to two isomers, (E, 9%) and (Z, 91%). Coordination of Cd(NO3)2 and Zn(NO3)2 yielded the complexes and. These compounds have significantly reduced barriers to rotation about the tertiary amide C-N bond compared with the free ligand (-OBzl:18.5 kcal mol-1 in CDBr3;: 12.9 kcal mol-1 in (CD3)2CO;: 13.8 kcal mol-1 in (CD3)2CO). Both complexes readily undergo transesterification in methanol or CD3OD. Experimental pseudo-first order rate constants were determined in CD3OD and (CD3)2CO:CD3OD (3:1;). It was found that the zinc complex (k=(2.28+/-0.02)x10(-4) s-1) is significantly more reactive than the cadmium complex (k=(1.41+/-0.03)x10(-6) s-1). In order to study their tertiary amide cis-trans isomerization, the cadmium complex [(-OCH3)Cd(NO3)2] was synthesized, and the zinc complex [(-OCD3)Zn(NO3)2] was generated in situ in (CD3)2CO:CD3OD (3:1). The barriers to rotation were determined (:14.1 kcal mol-1 in CD3OD;: 13.4 kcal mol-1 in (CD3)2CO:CD3OD (3:1)). Our results show that the stronger Lewis-acid zinc(II) is significantly more active than cadmium(II) in the acceleration of the transesterification. This is in marked contrast to the tertiary amide bond rotation which is comparably fast with both metal ions. 相似文献
68.
69.
The objective of this study was to create a thin film optode for fast pH measurements that meets the requirements for imaging pH-responses from cells as well as for a future hybrid design for detection of multiple analytes simultaneously. The sensor is based on the covalent attachment of 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) to a film forming cellulose acetate material through a sulfonamide linkage. The synthesis routes of the cellulose material and regio-specific covalent attachment of the dye are described in detail. The sensor was sterilized in two different ways and showed excellent biocompatibility with Chinese hamster ovary cells. Imprints from cells and μm thin cell extensions were visualized when altering pH of the surrounding solution. The sensor was tested together with time-dependent sigmoidal calibrations giving pH determinations with an exceptional precision and accuracy during measurement within pH 6-8. The precision of the optode, calculated as pooled S.D. (n = 8) according to IUPAC recommendations between pH 6.641 and 7.742 was 0.0029. The accuracy was significantly better than the electrode used as reference during the measurements. The response time (0-95%) was 100 s between pH 6.641 and 7.742 and the reverse response (95-0%) was 80 s. The sensor shows great potential for extra-cellular pH determination over time during cell growth and pharmacological exposure. 相似文献
70.
Hanessian S Del Valle JR Xue Y Blomberg N 《Journal of the American Chemical Society》2006,128(32):10491-10495
The first enantiocontrolled total synthesis of the marine sponge metabolite chlorodysinosin A is described. The structure and absolute configuration are identical to those of dysinosin A except for the presence of a novel 2S,3R-3-chloroleucine residue in the former. A concise stereocontrolled synthesis of the new chlorine-containing amino acid fragment was developed. An X-ray cocrystal structure of synthetic chlorodysinosin A with the enzyme thrombin confirms the structure and configuration assignment achieved through total synthesis. Within the aeruginosin family of natural products, chlorodysinosin A is the most potent inhibitor of the serine proteases thrombin, factor VIIa, and factor Xa, which are critical enzymes in the process leading to platelet aggregation and fibrin mesh formation in humans. 相似文献