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121.
Audrey Di Martino Jean‐Pierre Broyer Daniel Schweich Claude de Bellefon Guenter Weickert Timothy F. L. McKenna 《大分子反应工程》2007,1(2):284-294
A novel stopped flow reactor system is described in the current work, along with the underlying design philosophy. While the concept of stopped flow technology is not recent, this system is the first to be designed with the objective of studying particle morphology, and to work at extremely short (40 ms) residence times. It is shown that traditional chemical engineering principles are required to properly design and operate this type of reactor, and that when correctly design, it is a very flexible tool for the study of nascent polymerisation of olefins.
122.
Dromey B Kar S Bellei C Carroll DC Clarke RJ Green JS Kneip S Markey K Nagel SR Simpson PT Willingale L McKenna P Neely D Najmudin Z Krushelnick K Norreys PA Zepf M 《Physical review letters》2007,99(8):085001
The first evidence of x-ray harmonic radiation extending to 3.3 A, 3.8 keV (order n>3200) from petawatt class laser-solid interactions is presented, exhibiting relativistic limit efficiency scaling (eta approximately n{-2.5}-n{-3}) at multi-keV energies. This scaling holds up to a maximum order, n{RO} approximately 8{1/2}gamma;{3}, where gamma is the relativistic Lorentz factor, above which the first evidence of an intensity dependent efficiency rollover is observed. The coherent nature of the generated harmonics is demonstrated by the highly directional beamed emission, which for photon energy hnu>1 keV is found to be into a cone angle approximately 4 degrees , significantly less than that of the incident laser cone (20 degrees ). 相似文献
123.
Aubert B Bona M Boutigny D Karyotakis Y Lees JP Poireau V Prudent X Tisserand V Zghiche A Garra Tico J Grauges E Lopez L Palano A Eigen G Stugu B Sun L Abrams GS Battaglia M Brown DN Button-Shafer J Cahn RN Groysman Y Jacobsen RG Kadyk JA Kerth LT Kolomensky YG Kukartsev G Lopes Pegna D Lynch G Mir LM Orimoto TJ Ronan MT Tackmann K Wenzel WA del Amo Sanchez P Hawkes CM Watson AT Held T Koch H Lewandowski B Pelizaeus M Schroeder T Steinke M Walker D Asgeirsson DJ Cuhadar-Donszelmann T Fulsom BG 《Physical review letters》2007,99(7):071801
We present updated measurements of CP-violating asymmetries in the decays B0-->D*(+/-)D(-/+) and B0-->D+D- using (383+/-4) x 10(6)B(B) pairs collected by the BABAR detector at the SLAC PEP-II B factory. We determine the time-integrated CP asymmetry A(D*(+/-)D(-/+))=0.12+/-0.06+/-0.02, and the time-dependent asymmetry parameters to be C(D*+D-)=0.18+/-0.15+/-0.04, S(D*+D-)=-0.79+/-0.21+/-0.06, C(D*-D+)=0.23+/-0.15+/-0.04, S(D*-D+)=-0.44+/-0.22+/-0.06, C(D+D-)=0.11+/-0.22+/-0.07, and S(D+D-)=-0.54+/-0.34+/-0.06, where the first uncertainty is statistical and the second is systematic. 相似文献
124.
The current work presents the results from an investigation of the mechanical behavior of single crystals of the energetic material pentaerythritol tetranitrate (PETN) using a nano‐indentation technique. The indentation tests have been performed on the maximum growth habit face (110) of the PETN, using a spherical, Berkovich and an anisometric (wedge‐shaped) tip. The load displacement curves along with analysis have been used to extract the mechanical properties and identify the anisotropic indentation modulus for the PETN. The indentation moduli of the PETN single crystal were found to decrease as indentation depth increases and become independent of indentation depth for depths greater than 200 nm for the spherical indenter and 300 nm for the anisometric wedge indenter and Berkovich tip. The indentation modulus obtained from spherical tip indentation is compared with the results calculated by using literature values of the elastic constants. The wedge indenter measurements and Berkovich indentation at various tip orientations are different due to the anisotropy of the PETN. The yield behaviors of the PETN single crystal were also explored using both spherical and wedge tip indentation and the differences are discussed. 相似文献
125.
Błażewska KM Haiges R Kashemirov BA Ebetino FH McKenna CE 《Chemical communications (Cambridge, England)》2011,47(22):6395-6397
Under certain conditions, the phosphonocarboxylate analogue (3) of the bisphosphonate drug minodronate (4) in contact with borosilicate glassware reversibly forms an isolable dimer complex of boron, as revealed by the X-ray crystallographic structure of the (R,R/S,S) complex and supported by NMR and HRMS data. 相似文献
126.
Carta F Aggarwal M Maresca A Scozzafava A McKenna R Supuran CT 《Chemical communications (Cambridge, England)》2012,48(13):1868-1870
The zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1) is inhibited by several classes of zinc-binders (sulfonamides, sulfamates, and sulfamides) as well as by compounds which do not interact with the metal ion (phenols, polyamines and coumarins). Here we report a new class of potent CA inhibitors which bind the zinc ion: the dithiocarbamates (DTCs). They coordinate to the zinc ion from the enzyme active site in monodentate manner and establish many favorable interactions with amino acid residues nearby. Several low nanomolar CA I, II and IX inhibitors were detected. 相似文献
127.
McKenna MH Gibson RG Walker BE McKenna J Winslow NW Kofford AS 《The Journal of the Acoustical Society of America》2012,131(1):35-46
Infrasound data were collected using portable arrays in a region of variable terrain elevation to quantify the effects of topography on observed signal amplitude and waveform features at distances less than 25 km from partially contained explosive sources during the Frozen Rock Experiment (FRE) in 2006. Observed infrasound signals varied in amplitude and waveform complexity, indicating propagation effects that are due in part to repeated local maxima and minima in the topography on the scale of the dominant wavelengths of the observed data. Numerical simulations using an empirically derived pressure source function combining published FRE accelerometer data and historical data from Project ESSEX, a time-domain parabolic equation model that accounted for local terrain elevation through terrain-masking, and local meteorological atmospheric profiles were able to explain some but not all of the observed signal features. Specifically, the simulations matched the timing of the observed infrasound signals but underestimated the waveform amplitude observed behind terrain features, suggesting complex scattering and absorption of energy associated with variable topography influences infrasonic energy more than previously observed. 相似文献
128.
McKenna MF Ross D Wiggins SM Hildebrand JA 《The Journal of the Acoustical Society of America》2012,131(1):92-103
Underwater radiated noise measurements for seven types of modern commercial ships during normal operating conditions are presented. Calibrated acoustic data (<1000 Hz) from an autonomous seafloor-mounted acoustic recorder were combined with ship passage information from the Automatic Identification System. This approach allowed for detailed measurements (i.e., source level, sound exposure level, and transmission range) on ships of opportunity. A key result was different acoustic levels and spectral shapes observed from different ship-types. A 54 kGT container ship had the highest broadband source level at 188 dB re 1 μPa@1m; a 26 kGT chemical tanker had the lowest at 177 dB re 1 μPa@1m. Bulk carriers had higher source levels near 100 Hz, while container ship and tanker noise was predominantly below 40 Hz. Simple models to predict source levels of modern merchant ships as a group from particular ship characteristics (e.g., length, gross tonnage, and speed) were not possible given individual ship-type differences. Furthermore, ship noise was observed to radiate asymmetrically. Stern aspect noise levels are 5 to 10 dB higher than bow aspect noise levels. Collectively, these results emphasize the importance of including modern ship-types in quantifying shipping noise for predictive models of global, regional, and local marine environments. 相似文献
129.
Ramakrishna B Kar S Robinson AP Adams DJ Markey K Quinn MN Yuan XH McKenna P Lancaster KL Green JS Scott RH Norreys PA Schreiber J Zepf M 《Physical review letters》2010,105(13):135001
We demonstrate experimentally that the relativistic electron flow in a dense plasma can be efficiently confined and guided in targets exhibiting a high-resistivity-core-low-resistivity-cladding structure analogous to optical waveguides. The relativistic electron beam is shown to be confined to an area of the order of the core diameter (50 μm), which has the potential to substantially enhance the coupling efficiency of electrons to the compressed fusion fuel in the Fast Ignitor fusion in full-scale fusion experiments. 相似文献
130.
K. Quinn P. A. Wilson B. Ramakrishna G. Sarri L. Romagnani A. Pipahl O. Willi L. Lancia J. Fuchs D. C. Carroll M. N. Quinn P. Gallegos X. H. Yuan P. McKenna R. J. Clarke D. Neely M. Notley A. Macchi M. Borghesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):293-297
New method of neutron spectrum recovery described in the paper involves accelerated deuterons (that produce neutrons in DD
reaction) and allows getting neutron spectrum in any direction from computed time-velocity characteristics of deuterons. Time of flight signals registered in various distances and directions are used, that makes
information involved in the recovery process (Monte-Carlo simulation) more complete than in a one-directional case, although
additional assumption about axial symmetry of deuterons motion, is required. In the paper recent results of two standard tests
of the proposed method are presented demonstrating its capability to recover neutron spectrum from time-of-flight signals. 相似文献