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531.
532.
We consider classes of ideals which generalize the mixed product ideals introduced by Restuccia and Villarreal (see [5]), and also generalize the expansion construction by Bayati and Herzog [1]. We compute the minimal graded free resolution of generalized mixed product ideals and show that the regularity of a generalized mixed product ideal coincides with the regularity of the monomial ideal by which it is induced. 相似文献
533.
Anthony M. Haag Audrie M. Medina Ariel E. Royall Norbert K. Herzog David W. Niesel 《Journal of mass spectrometry : JMS》2013,48(6):732-739
Antibiotic resistance is a growing problem worldwide. For this reason, clinical laboratories often determine the susceptibility of the bacterial isolate to a number of different antibiotics in order to establish the most effective antibiotic for treatment. Unfortunately, current susceptibility assays are time consuming. Antibiotic resistance often involves the chemical modification of an antibiotic to an inactive form by an enzyme expressed by the bacterium. Selected reaction monitoring (SRM) has the ability to quickly monitor and identify these chemical changes in an unprecedented time scale. In this work, we used SRM as a technique to determine the susceptibility of several different antibiotics to the chemically modifying enzymes β‐lactamase and chloramphenicol acetyltransferase, enzymes used by bacteria to confer resistance to major classes of commonly used antibiotics. We also used this technique to directly monitor the effects of resistant bacteria grown in a broth containing a specific antibiotic. Because SRM is highly selective and can also identify chemical changes in a multitude of antibiotics in a single assay, SRM has the ability to detect organisms that are resistant to multiple antibiotics in a single assay. For these reasons, the use of SRM greatly reduces the time it takes to determine the susceptibility or resistance of an organism to a multitude of antibiotics by eliminating the time‐consuming process found in other currently used methods. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
534.
In this paper the asymptotic behavior of the Castelnuovo$ndash;Mumford regularity of powers of a homogeneous ideal I is studied. It is shown that there is a linear bound for the regularity of the powers I whose slope is the maximum degree of a homogeneous generator of I, and that the regularity of I is a linear function for large n. Similar results hold for the integral closures of the powers of I. On the other hand we give examples of ideal for which the regularity of the saturated powers is asymptotically not a linear function, not even a linear function with periodic coefficients. 相似文献
535.
Dirk Steinborn Steffi Becke Renate Herzog Mike Günther Robert Kircheisen Helen Stoeckli-Evans Clemens Bruhn 《无机化学与普通化学杂志》1998,624(8):1303-1307
Heteroatom-functionalized Methylgold Complexes: Synthesis and Structure of Chloromethyl(triphenylphosphine)- and Phenylthiomethyl(trimethylphosphine)gold [AuCl(PPh3)] reacts with Mg(CH2Cl)Cl, prepared in situ from CH2ClI and iPrMgCl, in ether at –65 °C to give [Au(CH2Cl)(PPh3)] ( 1 a ). 1 a reacts with LiI, NaOMe and PPh3 to give [Au(CH2I)(PPh3)] ( 2 ), [Au(CH2OMe)(PPh3)] ( 3 ) and [Au(CH2PPh3)(PPh3)]Cl ( 4 ), respectively. 2 decomposes rapidly at room temperature, yielding ethylene and [AuI(PPh3)]. The reaction of [AuCl(PMe3)] with LiCH2SPh in THF affords [Au(CH2SPh)(PMe3)] ( 5 ). The chloromethyl and the phenylthiomethyl complex 1 a and 5 were isolated and characterized by NMR (1H, 13C, 31P) spectroscopy as well as by single-crystal X-ray structure analysis. In the solid state discrete molecules of 1 a and 5 are found with linear C–Au–P units [C–Au–P 179,8(4)° ( 1 a ), 179,1(1)° ( 5 )]. The angle Au–C–Cl (115,4(6)°) in 1 a is slightly greater than the tetrahedral angle. 相似文献
536.
Matthias Frese Philip Saumer Yizhi Yuan Doreen Herzog Dorothea Höpfner Prof. Dr. Aymelt Itzen Prof. Dr. Andreas Marx 《Angewandte Chemie (International ed. in English)》2023,62(8):e202213279
Diadenosine polyphosphates (ApnAs) are non-canonical nucleotides whose cellular concentrations increase during stress and are therefore termed alarmones, signaling homeostatic imbalance. Their cellular role is poorly understood. In this work, we assessed ApnAs for their usage as cosubstrates for protein AMPylation, a post-translational modification in which adenosine monophosphate (AMP) is transferred to proteins. In humans, AMPylation mediated by the AMPylator FICD with ATP as a cosubstrate is a response to ER stress. Herein, we demonstrate that Ap4A is proficiently consumed for AMPylation by FICD. By chemical proteomics using a new chemical probe, we identified new potential AMPylation targets. Interestingly, we found that AMPylation targets of FICD may differ depending on the nucleotide cosubstrate. These results may suggest that signaling at elevated Ap4A levels during cellular stress differs from when Ap4A is present at low concentrations, allowing response to extracellular cues. 相似文献