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The efI'ects of smooth space variations of temperature and electric field on the charge-densitywave (CDW) dynamics are analyzed within the Gor'kov model. It is shown that such variations cause a generation of the phase-slip (PS) centers within the bulk of the specimen. The bulk PS's are responsible for the splitting of the narrow-band-noise (NBN) fundamental frequencies, as well as for the appearance of the additional low-frequency and satellite peaks in the voltage spectra. Taking into account the dependence of the threshold electric field for the CDW motion on temperature, we interpret various experimental results concerning the NBN in samples subjected to finite temperature gradients. We discuss in particular a dependence of the NBN splitting on temperature, temperature gradient, and external electric field, as well as on some characteristics of the samples, such as the length and the presence of strong defects.

Rhumb.-On donne une revue de I'approche Ginzburg-Landau des instabilites structurelles, qui sont observies dans les conducteurs unidimensionnels. La statique des fluctuations d'une chaine Golk est dtcrite. Le traitement par Brazovskii et Dzyaloshinskii de la dynamique correspondante est aussi brikvement mentionnt, en relation avec la supraconductivitt de Frohlich. Finalement nous dCcrivons les effets de couplages interchaines sur I'ordre transversal des systkmes a chaines. Le modkle est utilisC pour interprkter les instabilitks de TTF-TCNQ a 2 k,.