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X. Zhang Robert R. Fuller Robin L. Dahlgren Kurt Potgieter Rhanor Gillette J. V. Sweedler 《Analytical and bioanalytical chemistry》2001,369(3-4):206-211
Quantitative analysis of signaling molecules from single cells and cellular materials requires careful validation of the
analytical methods. Strategies have been investigated that enable single neurons and neuronal tissues to be stored before
being assayed for many low-weight, biologically active molecules, such as serotonin, dopamine, and citrulline. Both metacerebral
cell and pedal ganglia homogenates isolated from Pleurobranchaea californica have been studied by capillary electrophoresis with two complimentary laser-induced fluorescence detection methods. For homogenized
ganglia samples, several cellular analytes (such as arginine and citrulline) are unaffected by standing at room temperature
for days. Many other analytes in the biological matrix, including the catecholamines and indolamines, degrade by 20% within
10 h at room temperature. Rapidly freezing samples or preserving them with ascorbic acid preserves more than 80% of the dopamine
and about 70% of the serotonin even after five days. In addition, serotonin and dopamine remain completely stable for at least
five days by combining the ascorbic acid preservation and freezing at –20 °C. The timing of preservation is critical in maintaining
the original composition of the biological samples. Using our optimum storage protocol of freezing the sample within 2 h after
isolation, we can store frozen homogenate ganglia samples for more than four weeks before assay while still obtaining losses
less than 10% of the original serotonin and dopamine. The nanoliter-volume single cell samples, however, must be analyzed
within 4 h to obtain losses of less than 10% for serotonin related metabolites.
Received: 23 August 2000 / Revised: 2 November 2000 / Accepted: 7 November 2000 相似文献
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The adsorption and decomposition of H2S on the Ge(100) surface is investigated. H2S is a simple sulfur containing molecule that eventually decomposes to yield hydrogen gas and deposits sulfur on the germanium surface. The surface reactions of H2S are investigated by ultraviolet photoelectron spectroscopy, Auger electron spectroscopy, and temperature programmed desorption. Room temperature exposure of H2S to Ge(100) results in dissociative adsorption which can be followed easily by ultraviolet photoelectron spectroscopy. Warming the H2S exposed surface results in some molecular desorption and further decomposition of the adsorbed species. At saturation, 0.25 ML of H2S decomposes generating 0.5 ML of atomic hydrogen. Above the hydrogen desorption temperature some etching of the germanium surface is observed by sulfur. The etch product, GeS, is subsequently observed in temperature programmed desorption experiments. Exposure of H2S to the Ge surface at elevated temperatures leads to higher sulfur coverages. A sulfur coverage approaching 0.5 ML can be deposited at the higher exposure temperatures. 相似文献
296.
S. Fuller J. Hopwood A. Rahman N. Shinde G. J. Tiddy G. S. Attard O. Howell S. Sproston 《Liquid crystals》1992,12(3):521-529
We have studied the lyotropic liquid-crystalline behaviour of cationic surfactants containing a potentially thermotropic moiety, a terminal cyanobiphenyloxy group. Both mono-alkyl and mid-chain substituted dialkyl surfactants have been examined using optical microscopy and NMR spectroscopy. Incorporation of the cyanobiphenyloxy group destabilizes the hexagonal and bicontinuous cubic phases, with only an extensive lamellar region being observed. For the dialkyl surfactant there is a range of compositions where two lamellar phases co-exist, one water-rich and the second surfactant-rich. 相似文献
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Fuller BJ 《Cryo letters》2004,25(6):375-388
In the fifty years since the establishment of the cryoprotective effect of glycerol, cell banking by cryopreservation has become routine in many areas of biotechnology and medicine. Cryoprotectant addition has become a rather mundane step within the overall protocol. However, for future advances in cryobiology and to meet new challenges in the clinical use of cryopreserved cells or tissues, it will be essential to have an understanding of the development and current status of the biological and chemical knowledge on cryoprotectants (CPA). This review was undertaken to outline the history of CPA use, the important properties of CPA in relation to freezing damage, and what can be learnt from natural freezing-tolerant organisms. The conflicting effects of protection and toxicity resulting from use of CPA are discussed, and the role of CPA in enhancing glassy states in the emerging field of vitrification are also set out. 相似文献
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