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David N. Kuhn Michael Knauf P.K. Stumpf 《Archives of biochemistry and biophysics》1981,209(2):441-450
The localization of acetyl-CoA synthetase in the spinach leaf cell was examined. When the different compartments of lysed spinach protoplasts were assayed for marker enzymes and acetyl-CoA synthetase, it was determined that the synthetase was totally localized in the chloroplast compartment. Analysis of spinach leaf for free acetate revealed that this acid was present at a 1 mm level in the leaf cell. It is suggested that free acetate probably derived from a number of sources in the cell diffuses into the chloroplast stroma compartment where it is converted to acetyl-CoA and thence employed for biosynthetic reactions. Thus, free acetate is metabolically inert in the leaf cell until it is transported to the only compartment that contains acetyl-CoA synthetase, namely the chloroplast. 相似文献
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Dr. G. Schleicher W. E. Stumpf U. Drews K. U. Thiedemann M. Sar 《Histochemistry and cell biology》1985,82(5):453-461
Summary The distribution of specific nuclear binding sites for androgens and estrogens in the male accessory sex organs of the mouse
was assessed by autoradiography with3H dihydrotestosterone (3H DHT) and3H estradiol (3H E2).
With3H DHT nuclear labeling differed among the epithelia of the organs. It was high in seminal vesicle and ampullary gland, moderate
in ventral prostate, urethral gland, prostatic excretory ducts and the ampulla ductus deferentis, low in dorsal prostate and
low or absent in coagulation gland. With3H E2, in contrast, epithelial nuclear labeling was high only in coagulation gland, moderate or low in seminal vesicle, low or
absent in ventral and dorsal prostate and absent in ampullary gland and ampulla ductus deferentis. In the lamina propria of
all organs nuclear labeling with3H DHT was generally moderate and existed only in some cells, with the highest number in the ampulla ductus deferentis. With3H E2, nuclear labeling in the lamina propria showed a high intensity in all organs, except in ventral and dorsal prostate which
remained unlabeled. Many labeled cells were found in the deferent duct and its ampulla, while in the other organs only a few
cells showed nuclear labeling with3H E2. In the smooth muscle sheath of all organs, some muscle cells were moderately labeled with3H DHT, but not with3H E2.
The results indicate the presence of nuclear receptors in male accessory sex organs for both dihydrotestosterone and estradiol.
The differential patterns of3H DHT and3H E2 nuclear uptake suggest differential sensitivities of the individual organs and their tissue compartments for androgens and
estrogens.
Supported by PHS grant NSO9914 to W.E.S. and Deutsche Forschungsgemeinschaft Dr94/4 to U.D. The work of Dr. Schleicher and
his stay in Chapel Hill were additionally sponsored by Studienstiftung des Deutschen Volkes and Boehringer-Ingelheim Fonds 相似文献
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H. F. Stumpf 《Development genes and evolution》1967,158(3):315-330
Summary Evidence for the existence of a concentration gradient in the segments ofGalleria mellonella and ofRhodnius prolixus has been reported elsewhere. InGalleria it is possible to determine the functional form of the gradient by measuring the deviation of the scales from their normal direction after the transplantation of a piece of the intersegmental integument from the anterior or the posterior margin into the segment. The calculated values indicate the force with which the scales are oriented in an axial direction. This force corresponds to the slope of the concentration gradient.Different curves are found for the forces depending on the origin of the graft (anterior or posterior margin). This seems to be the result of unequal shrinking of the grafts. The geometrical mean of the average of the forces for anterior grafts and that for posterior grafts is nearly constant all over the segment (only the parts near the segment margins could not be included in the measurement). Thus the concentration gradient declines almost linearly. Linearly declining concentrations are expected between two different but constant concentrations which may be assumed to be located in the anterior and the posterior margin of the segment.
Ich danke Herrn Dr.Marcus für die großzügige Überlassung seiner Präparate und Herrn Dr.Schmidt-König für die hilfreiche Diskussion der statistischen Möglichkeiten dieses Falles. Die Arbeit wurde mit Unterstützung der Deutschen Forschungsgemeinschaft ausgeführt. 相似文献
Ich danke Herrn Dr.Marcus für die großzügige Überlassung seiner Präparate und Herrn Dr.Schmidt-König für die hilfreiche Diskussion der statistischen Möglichkeiten dieses Falles. Die Arbeit wurde mit Unterstützung der Deutschen Forschungsgemeinschaft ausgeführt. 相似文献
6.
Wheat germ acetyl CoA carboxylase was purified 600-fold over the crude homogenate. The purified enzyme gave rise to complex electrophoretic patterns in dissociating gels. As isolated, the activity of wheat germ acetyl CoA carboxylase exhibited profound dependence on the composition of the reaction mixture. In addition to the substrates MgATP, HCO3, and acetyl CoA, the enzyme required both free Mg2+ and K+ for optimal activity. The effects of the two ions were additive. At pH 8.5, Mg2+ activated the carboxylase by adding to the enzyme prior to the other reactants in an equilibrium ordered reaction mechanism. 相似文献
7.
Summary The presence of specific binding sites for radiolabelled vertebrate-type and arthropod-type steroid hormones was investigated in several organs including salivary gland, and central nervous system of third instar Calliphora vicina larvae by thaw-mount autoradiography. Ponasterone A, a 20-hydroxyecdysone agonist and 20-hydroxyecdysone are the only steroids which bind to nuclear high affinity binding sites. These binding sites are DNA associated while nucleoli show no tracer binding. Ecdysone, an endogenous 20-hydroxyecdysone precursor, is taken up by target cells but no significant nuclear binding occurs. 1,25-Dihydroxyvitamin D3 concentrates in cytoplasm only and its uptake is highest compared to all other steroids. Progesterone and testosterone show weak accumulation in the cytoplasm, while for cholesterol, corticosterone, cortisol, dexamethasone, dihydrotestosterone and estradiol-17, no noticeable uptake occurs. For ponasterone A, a clear time dependence of uptake and intracellular distribution is visible, suggesting the existence and involvement of specific ecdysteroid uptake and transport mechanisms. These results suggest the presence of binding sites for various mammalian steroids in insects. Whether vertebrate steroid hormones or metabolites of them play a role in insects or whether the uptake and binding is based on chemical similarities alone without biological significance remains to be further investigated. 相似文献
8.
Co-localization of ecdysteroid receptors and c-fos-like protein in the brain of Manduca sexta larvae
Hans-Jürgen Bidmon Noelle Audrey Granger Walter Erich Stumpf 《Development genes and evolution》1991,200(3):149-155
Summary The presence of c-fos, a marker for cell activation, was investigated in cerebral neurons actively expressing ecdysteroid receptors during larval-pupal development in the tobacco hornworm, Manduca sexta. Colocalization was accomplished by ecdysteroid autoradiography using the tritiated high affinity 20-hydroxyecdysone agonist ponasterone A and immunocytochemistry with an antibody to a peptide sequence which is highly conserved in both human and murine c-fos. Immunoreactivity to a c-fos-like protein(s) was present in nuclei of many neurons of all the developmental stages examined. However, with the exception of the optic lobe, cells expressing nuclear ecdysteroid receptors were more immunoreactive than non-ecdysteroid-binding neurons. These data suggest that ecdysteroid-induced gene activation and translation may involve c-fos expression.
Offprint requests to: H.-J. Bidmon 相似文献
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Avocado mesocarp extracts contain both acyl-CoA and acyl-acyl carrier protein (ACP) hydrolase activities. These activities have been separated by a sequence of ammonium sulfate fractionations, DEAE-cellulose, and hydroxyapatite column chromatography. Two distinct acyl-CoA hydrolase fractions and one acyl-ACP hydrolase fraction were obtained. The acyl-ACP hydrolase fraction was essentially free of acyl-CoA hydrolase activity, had a pH optimum of 9.5 and a molecular weight of 70–80,000 based on sucrose density gradient centrifugation and gel filtration chromatography. Substrate specificity studies showed that lauroyl-ACP, myristoyl-ACP, palmitoyl-ACP, and stearoyl-ACP were slowly hydrolyzed but oleoyl-ACP was rapidly hydrolyzed to free fatty acid. These results suggest a possible role for acyl-ACP hydrolase as one component of a switching system which allows, indirectly, acyl transfer from ACP to CoA derivatives in plant cells. 相似文献