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51.
A single atom in free space can have a strong influence on a light beam and a single photon can have a strong effect on a
single atom in free space. Regarding this interaction, two conceptually different questions can be asked: can a single atom
fully absorb a single photon and can a single atom fully reflect a light beam. The conditions for achieving the full effect
in either case are different. Here we discuss related questions in the context of an optical resonator. When shaping a laser
pulse properly it will be fully absorbed by an optical resonator, i.e., no light will be reflected and all the pulse energy
will accumulate inside the resonator before it starts leaking out. We show in detail that in this case the temporal pulse
shape has to match the time-reversed pulse obtained by the cavity’s free decay. On the other hand a resonator, made of highly
reflecting mirrors which normally reflect a large portion of any incident light, may fully transmit the light, as long as
the light is narrow band and resonant with the cavity. The analogy is the single atom—normally letting most of the light pass—which
under special conditions may fully reflect the incident light beam. Using this analogy we are able to study the effects of
practical experimental limitations in the atom-photon coupling, such as finite pulses, bandwidths, and solid angle coverage,
and to use the optical resonator as a test bed for the implementation of the quantum experiment. 相似文献
52.
We calculate the quantum correlations existing among the three output fields (pump, signal, and idler) of a triply resonant nondegenerate optical parametric oscillator operating above threshold. By applying the standard criteria [P. van Loock and A. Furusawa, Phys. Rev. A 67, 052315 (2003)], we show that strong tripartite continuous-variable entanglement is present in this well-known and simple system. Furthermore, since the entanglement is generated directly from a nonlinear process, the three entangled fields can have very different frequencies, opening the way for multicolored quantum information networks. 相似文献
53.
Ioannis Zalachoras Gwendolynn Grootaers Lisa TCM van Weert Yves Aubert Suzanne R de Kreij Nicole A Datson Willeke MC van Roon-Mom Annemieke Aartsma-Rus Onno C Meijer 《BMC neuroscience》2013,14(1):1-12
Background
Antisense oligonucleotide (AON)-mediated exon skipping is a powerful tool to manipulate gene expression. In the present study we investigated the potential of exon skipping by local injection in the central nucleus of the amygdala (CeA) of the mouse brain. As proof of principle we targeted the splicing of steroid receptor coactivator-1 (SRC-1), a protein involved in nuclear receptor function. This nuclear receptor coregulator exists in two splice variants (SRC-1a and SRC-1e) which display differential distribution and opposing activities in the brain, and whose mRNAs differ in a single SRC-1e specific exon.Methods
For proof of principle of feasibility, we used immunofluorescent stainings to study uptake by different cell types, translocation to the nucleus and potential immunostimulatory effects at different time points after a local injection in the CeA of the mouse brain of a control AON targeting human dystrophin with no targets in the murine brain. To evaluate efficacy we designed an AON targeting the SRC-1e-specific exon and with qPCR analysis we measured the expression ratio of the two splice variants.Results
We found that AONs were taken up by corticotropin releasing hormone expressing neurons and other cells in the CeA, and translocated into the cell nucleus. Immune responses after AON injection were comparable to those after sterile saline injection. A successful shift of the naturally occurring SRC-1a:SRC-1e expression ratio in favor of SRC-1a was observed, without changes in total SRC-1 expression.Conclusions
We provide a proof of concept for local neuropharmacological use of exon skipping by manipulating the expression ratio of the two splice variants of SRC-1, which may be used to study nuclear receptor function in specific brain circuits. We established that exon skipping after local injection in the brain is a versatile and useful tool for the manipulation of splice variants for numerous genes that are relevant for brain function. 相似文献54.
Electronic Structure Modulation in an Exceptionally Stable Non‐Heme Nitrosyl Iron(II) Spin‐Crossover Complex 下载免费PDF全文
Lucía Piñeiro‐López Dr. Norma Ortega‐Villar Prof. Dr. M. Carmen Muñoz Dr. Gábor Molnár Dr. Jordi Cirera Prof. Dr. Rafael Moreno‐Esparza Prof. Dr. Víctor M. Ugalde‐Saldívar Dr. Azzedine Bousseksou Prof. Dr. Eliseo Ruiz Prof. Dr. José A. Real 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12741-12751
The highly stable nitrosyl iron(II) mononuclear complex [Fe(bztpen)(NO)](PF6)2 (bztpen=N‐benzyl‐N,N′,N′‐tris(2‐pyridylmethyl)ethylenediamine) displays an S=1/2?S=3/2 spin crossover (SCO) behavior (T1/2=370 K, ΔH=12.48 kJ mol?1, ΔS=33 J K?1 mol?1) stemming from strong magnetic coupling between the NO radical (S=1/2) and thermally interconverted (S=0?S=2) ferrous spin states. The crystal structure of this robust complex has been investigated in the temperature range 120–420 K affording a detailed picture of how the electronic distribution of the t2g–eg orbitals modulates the structure of the {FeNO}7 bond, providing valuable magneto–structural and spectroscopic correlations and DFT analysis. 相似文献
55.
Paital AR Bertolasi V Aromí G Ribas-Ariño J Ray D 《Dalton transactions (Cambridge, England : 2003)》2008,(7):861-864
A perchlorate ligand in the rare mu4-1,1,2,2 binding mode is seen for the first time as the sole support for the assembly of two cationic [Cu II 2L]+ fragments (H3L = a dinucleating ligand) in the formation of a magnetically-exchanged tetranuclear cluster. 相似文献
56.
Highly regioselective annulation reactions of unsymmetrically substituted alkynes by primary 2-bromo or 2-chloroanilines are achieved with an efficient one-pot protocol, which relies on a regioselective TiCl4-catalyzed intermolecular hydroamination and a subsequent palladium-catalyzed intramolecular aza-Heck reaction. The use of unsymmetrically substituted alkynes in this strategy enables the synthesis of diversely functionalized indoles, with a regioselectivity that is complementary to the one obtained when employing Larock's annulation reaction. 相似文献
57.
Lorenzo Fernandez Pedro Viruela-Martin Julio Latorre Carmen Guillem Aurelio Beltrn Pedro Amors 《Journal of Molecular Structure》2008,850(1-3):94-104
Quantum chemical calculations using density functional theory have been carried out to investigate molecular precursors based on alumatranes which are one of the components with silatranes for the preparation of mesoporous aluminosilicate materials. In the same way, some oligomeric alumatranes of this study take part in chemical syntheses related to materials such as zeolites and alumina composite. Gas phase and solution equilibrium geometries of the alumatrane precursors were fully optimized at B3LYP level, modeling solvent effects using a self-consistent reaction field (SCRF). From these optimized geometries, calculations of the 1H, 13C and 27Al NMR chemical shifts at GIAO/B3LYP/6-31G(d,p) levels of theory have also been performed. This study has shown that the assumed conformations of the alumatrane precursors that have been derived from a previous work on a FAB-MASS analysis (Fast Atomic Bombardment Mass Spectroscopy) are confirmed by DFT calculations. All the conformations of alumatranes show that there would have transannular Al–N bond. Oligomeric alumatranes are composed of one or more two-membered Al2O2 rings where tricoordinated oxygen would be present. A good agreement between the experimental NMR data and the theoretical study on the chemical shifts of nucleus as 13C, 1H and 27Al from full geometry optimizations of the alumatrane precursors seems to corroborate the presence of the alumatrane precursors in the “atrane route”. 相似文献
58.
Aromí G Bouwman E Burzurí E Carbonera C Krzystek J Luis F Schlegel C van Slageren J Tanase S Teat SJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(35):11158-11166
A highly asymmetric Ni(II) cluster [Ni(4)(OH)(OMe)(3)(Hphpz)(4)(MeOH)(3)](MeOH) (1) (H(2)phpz=3-methyl-5-(2-hydroxyphenyl)pyrazole) has been prepared and its structure determined by means of single-crystal X-ray diffraction by using synchrotron radiation. Variable-temperature bulk-magnetization measurements show that the complex exhibits intramolecular-ferromagnetic interactions leading to a spin ground state S=4 with close-lying excited states. Magnetization and high-frequency EPR measurements suggest the presence of sizable Ising-type magnetic anisotropy, with zero-field splitting parameters D=-0.263 cm(-1) and E=0.04 cm(-1) for the spin ground state, and an isotropic g value of 2.25. The presence of both axial and transverse anisotropy was confirmed through low-temperature specific heat determinations down to 300 mK, but no slow relaxation of the magnetization was observed by AC measurements down to 1.8 K. Interestingly, AC susceptibility measurements down to temperatures as low as 23 mK showed no indication of slow relaxation of the magnetization in 1. Thus, despite the presence of an anisotropy barrier (U approximately 4.21 cm(-1) for the purely axial limit), the magnetization relaxation remains extremely fast down to the lowest temperatures. The estimated quantum tunneling rate, Gamma>0.667 MHz, makes this complex a prime candidate for observation of coherent tunneling of the magnetization. 相似文献
59.
Barrios LA Ribas J Aromí G Ribas-Ariño J Gamez P Roubeau O Teat SJ 《Inorganic chemistry》2007,46(17):7154-7162
The syntheses and X-ray structures of three isomeric 1D coordination polymers are reported. The complex [Co(dbm)2(MeOH)2] (1) was used as a precursor in these reactions. The preparation and structure of 1 is also presented; this mononuclear complex is in the cis configuration because this allows the formation of a network of intermolecular hydrogen bonds in the solid state. Reaction of 1 with 2,4,6-tris-(4-pyridyl)-1,3,5-triazine (4ptz) yields the polymers [Co(dbm)2(4ptz)]n.nTHF (2a), [Co(dbm)2(4ptz)]n.0.75nTHF.0.5nEt2O (2b), and [Co(dbm)2(4ptz)]n.3nDMF (2c) in the form of zigzag chains, instead of the expected honeycomb architectures. This is because of the establishment of extended pi-pi stacking throughout these solids, which could not have occurred otherwise. Compounds 2a, 2b, and 2c are solvatomorphs, and formation of either one of them depends on the exact conditions of crystallization, which lead to significant differences in the supramolecular organization of the chains. Bulk magnetic measurements on 2a reveal weak antiferromagnetic exchange within the chains and small ordering throughout the solid that results in the manifestation of the phenomenon of spin canting, whereas for 2c the different supramolecular organization causes the antiferromagnetic exchange not to result in spin canting. 相似文献
60.
KM Varier AM Vinodkumar NVSV Prasad PV Madhusudhana Rao DL Sastry Lagy T Baby MC Radhakrishna NG Puttaswamy JJ Das P Sugathan N Madhavan AK Sinha DO Kataria 《Pramana》1999,53(3):529-533
Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies.
Coupled channel calculations incorporating couplings to 2+ and 3− states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements
had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer
were carried out for 46,48Ti+61Ni systems. The present paper gives the results of these studies. 相似文献