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David R. Walt Venetka Agayn Karen Bronk Steven Barnard 《Applied biochemistry and biotechnology》1993,41(1-2):129-138
Optical sensors are prepared by immobilizing an indicating layer on the distal end of a fiber optic cable. Dyes, enzymes, and antibodies can all be incorporated into the layer using a variety of immobilization techniques. Much of the present work is devoted to developing novel indicating schemes by combining appropriate recognition schemes into polymeric matrices. 相似文献
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Bushra Y Ahmed Sridhara Chakravarthy Ruben Eggers Wim TJMC Hermens Jing Ying Zhang Simone P Niclou Christiaan Levelt Fred Sablitzky Patrick N Anderson AR Lieberman Joost Verhaagen 《BMC neuroscience》2004,5(1):1-11
Background
As development proceeds the human embryo attains an ever more complex three dimensional (3D) structure. Analyzing the gene expression patterns that underlie these changes and interpreting their significance depends on identifying the anatomical structures to which they map and following these patterns in developing 3D structures over time. The difficulty of this task greatly increases as more gene expression patterns are added, particularly in organs with complex 3D structures such as the brain. Optical Projection Tomography (OPT) is a new technology which has been developed for rapidly generating digital 3D models of intact specimens. We have assessed the resolution of unstained neuronal structures within a Carnegie Stage (CS)17 OPT model and tested its use as a framework onto which anatomical structures can be defined and gene expression data mapped.Results
Resolution of the OPT models was assessed by comparison of digital sections with physical sections stained, either with haematoxylin and eosin (H&E) or by immunocytochemistry for GAP43 or PAX6, to identify specific anatomical features. Despite the 3D models being of unstained tissue, peripheral nervous system structures from the trigeminal ganglion (~300 μm by ~150 μm) to the rootlets of cranial nerve XII (~20 μm in diameter) were clearly identifiable, as were structures in the developing neural tube such as the zona limitans intrathalamica (core is ~30 μm thick). Fourteen anatomical domains have been identified and visualised within the CS17 model. Two 3D gene expression domains, known to be defined by Pax6 expression in the mouse, were clearly visible when PAX6 data from 2D sections were mapped to the CS17 model. The feasibility of applying the OPT technology to all stages from CS12 to CS23, which encompasses the major period of organogenesis for the human developing central nervous system, was successfully demonstrated.Conclusion
In the CS17 model considerable detail is visible within the developing nervous system at a minimum resolution of ~20 μm and 3D anatomical and gene expression domains can be defined and visualised successfully. The OPT models and accompanying technologies for manipulating them provide a powerful approach to visualising and analysing gene expression and morphology during early human brain development. 相似文献54.
55.
E. Barnard N. Coetzee J. A. M. de Villiers D. Reitmann P. van der Merwe 《Zeitschrift für Physik A Hadrons and Nuclei》1973,260(3):197-207
A study was made of the (n, n), (n, n′), and (n, n′ γ) reactions which occur when a natural rubidium scattering sample is exposed to mono-energetic neutron fluxes of energies ranging from 120 to 1910 keV. Total cross sections, elastic scattering angular distributions and excitation functions for inelastic scattering were measured with a neutron time-of-flight spectrometer. Results are compared with Hauser-Feshbach theory. A 40 cc Ge(Li) detector was used in the time-gated mode to measure γ-rays from the (n, n′ γ) reaction. The latter measurements were used to refine and extend the energy level schemes derived from neutron spectroscopy. Several new levels were discovered in the low-lying (below 1900 keV) energy level spectra of85Rb and87Rb. Gamma decay schemes and branching ratios were determined for the low-lying levels of85Rb and87Rb. 相似文献
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Reversible potentials of partially charged α- and β-Ni(OH)2 electrodes have been measured in both the homogeneous and heterogeneous potential-composition regions. From the points of transition between these regions, nickel oxidation states of the least oxidised coexisting phases U and U1 have been measured as 2.25.Experimental emf—oxidation state measurements for both the β and α/λ-phase couples are found to be in good agreement with theoretically derived expressions. Direct measurement of the oxidation states of the complementary coexisting phases V and V1 has not been possible. From considerations of the homogeneous emf—composition regions it is deduced that the oxidised species are dissociated in the host lattice, in both the β- and α/λ-phase systems. 相似文献
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