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21.
Hypoxia stimulates ventilation, but when it is sustained, a decrease in the response is often seen. The mechanism of this depression or "roll off" is unclear. In this study we attempted to localize the responsible mechanism at one of three possible sites: the carotid bodies, the central nervous system (CNS), or the ventilatory apparatus. The ventilatory response to sustained hypoxia (PETO2, 40-50 Torr) was tested in 5 awake and 14 anesthetized adult cats. The roll off was found in both anesthetized and awake cats. Isocapnic hypoxia initially increased ventilation as well as phrenic and carotid sinus nerve activity in anesthetized cats (288 +/- 31, 269 +/- 31, 273 +/- 29% of control value, respectively). During the roll off, ventilation and phrenic nerve activity decreased similarly (to 230 +/- 26 and 222 +/- 28%, respectively after the roll off), but in contrast carotid sinus nerve activity remained unchanged (270 +/- 26%). Thus the ventilatory roll off was reflected in phrenic but not in carotid sinus nerve activity. We conclude that the cat represents a useful animal model of the roll off phenomenon and that the mechanism responsible for the secondary decrease in ventilation lays within the CNS. 相似文献
22.
Laurence Marechal Pierre Guillemaut Jean-Michel Grienenberger Geneviève Jeannin Jacques-Henry Weil 《Plant molecular biology》1986,7(4):245-253
Summary Two bean mitochondria methionine transfer RNAs, purified by RPC-5 chromatography and two-dimensional gel electrophoresis, have been sequenced usingin vitro post-labeling techniques.One of these tRNAsMet has been identified by formylation using anE. coli enzyme as the mitochondrial tRNAF
Met. It displays strong structural homologies with prokaryotic and chloroplast tRNAF
Met sequences (70.1–83.1%) and with putative initiator tRNAm
Met genes described for wheat, maize andOenothera mitochondrial genomes (88.3–89.6%).The other tRNAMet, which is the mitochondrial elongator tRNAF
Met, shows a high degree of sequence homology (93.3–96%& with chloroplast tRNAm
Met, but a weak homology (40.7%) with a sequenced maize mitochondrial putative elongator tRNAm
Met gene.Bean mitochondrial tRNAF
Met and tRNAm
Met were hybridized to Southern blots of the mitochondrial genomes of wheat and maize, whose maps have been recently published (15, 22), in order to locate the position of their genes. 相似文献
23.
The proα2 (V) collagen gene (COL5A2) maps to 2q14→2q32, syntenic to the proα1 (III) collagen locus (COL3A1) 总被引:3,自引:0,他引:3
Cécile Huerre-Jeanpierre Isabelle Henry M. Bernard Pia Gallano Dominique Weil K. H. Grzeschik F. Ramirez Claudine Junien 《Human genetics》1986,73(1):64-67
Summary A recombinant probe specific for the pro2 chain of human Type V collagen has been used for the localization of the corresponding gene (COL5A2) to chromosome 2. Regional mapping by in situ hybridization and analysis of DNA from humanxrodent cell lines indicated that COL5A2 is confined within the segment 2q142q32, thus syntenic to the pro1 (III) collagen gene (COL3A1). 相似文献
24.
The review sums up data on gene mapping studies of tRNAs of chloroplasts from maize, beans, Euglena, Cyanophora. The mechanisms of splicing of tRNA2Ile from maize chloroplasts and coded for by a gene of unusual length was investigated. 相似文献
25.
Richard F. Selden Andre Steinmetz Lee McIntosh Lawrence Bogorad Gerard Burkard Mfika Mubumbila Marcel Kuntz Edwin J. Crouse Jacques H. Weil 《Plant molecular biology》1983,2(3):141-153
A minimum of 37 genes corresponding to tRNAs for 17 different amino acids have been localized on the restriction endonuclease cleavage site map of theZea mays chloroplast DNA molecule. Of these, 14 genes corresponding to tRNAs for 11 amino acids are located in the larger of the two single-copy regions which separate the two inverted copies of the repeat region. One tRNA gene is in the smaller single-copy region. Each copy of the large repeated sequence contains, in addition to the ribosomal RNA genes, 11 tRNA genes corresponding to tRNAs for 8 amino acids. The genes for tRNA2 Ile and tRNAAla map in the ribosomal spacer sequence separating the 16S and 23S ribosomal RNA genes. The three isoaccepting species for the tRNAsLeu and the three for tRNAsSer, as well as the two isoaccepting species for tRNAAsn, tRNAGly, tRNAsIle, tRNAsMet, tRNAsThr, are shown to be encoded at different loci. Two independent methods have been used for the localization of tRNA genes on the physical map of the maize chloroplast DNA molecule: (a) cloned chloroplast DNA fragments were hybridized with radioactively-labelled total 4S RNAs, the hybridized RNAs were then eluted, and identified by two-dimensional polyacrylamide gel electrophoresis, and (b) individual tRNAs were32P-labelledin vitro and hybridized to DNA fragments generated by digestion of maize chloroplast DNA with various restriction endonucleases. 相似文献
26.
27.
Hg ++ - a DCMU independent electron acceptor of photosystem II 总被引:3,自引:0,他引:3
D Miles P Bolen S Faraq R Goodin J Lutz A Moustafa B Rodriquez C Weil 《Biochemical and biophysical research communications》1973,50(4):1113-1119
Mercuric chloride functions as a direct electron acceptor from the quencher of fluorescence in Photosystem II. The photoreduction of ferricyanide, dichlorophenol-indophenol or methyl viologen is inhibited by mercuric ion while oxygen evolution is uneffected. Mercuric chloride supported oxygen evolution (mercury Hill reaction) is not prevented by DCMU or other similar electron transport inhibitors. 相似文献
28.
J Weil 《Journal of molecular biology》1969,43(2):351-355
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