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21.
Barbara O'Callaghan Monique Synguelakis Gildas Le Gal La Salle Nicolas Morel 《Biology of the cell / under the auspices of the European Cell Biology Organization》1994,81(2):121-130
Summary— A major antigen of the brush border membrane of Torpedo marmorata kidney was identified and purified by immunoprecipitation. The sequence of its 18 N terminal amino acids was determined and found to be very similar to that of mammalian aminopeptidase N (EC 3.4.11.2). Indeed aminopeptidase N activity was efficiently immunoprecipitated by monoclonal antibody 180K1. The purified antigen gives a broad band at 180 kDa after SDS-gel electrophoresis, which, after treatment by endoglycosidase F, is converted to a thinner band at 140 kDa. This antigen is therefore heavily glycosylated. Depending on solubilization conditions, both the antigen and peptidase activity were recovered either as a broad peak with a sedimentation coefficient of 18S (2% CHAPS) or as a single peak of 7.8S (1% CHAPS plus 0.2 % C12E9), showing that Torpedo aminopeptidase N behaves as an oligomer stabilized by hydrophobic interactions, easily converted into a 160 kDa monomer. The antigen is highly concentrated in the apical membrane of proximal tubule epithelial cells (600 gold particles/μm2 of brush border membrane) whereas no labeling could be detected in other cell types or in other membranes of the same cells (basolatéral membranes, vacuoles or vesicles). Monoclonal antibodies prepared here will be useful tools for further functional and structural studies of Torpedo kidney aminopeptidase N. 相似文献
22.
Rinkel Monique Hubert Jean-Claude Roux Brigitte Lett Marie-Claire 《Current microbiology》1994,29(5):249-254
AKlebsiella pneumoniae strain having mobilization helper potential has been isolated from the river Rhine. Analysis of the transconjugants resulting from the mobilization of nonconjugative pBR-type plasmids and RSF1010 derivatives showed that the transfer-helper capacity of theK. pneumoniae strain is related to the presence of a Tn3-like transposable element, Tn5403. This element has been identified and localized in a plasmid. 相似文献
23.
TOL plasmid pWW0 from Pseudomonas putida mt-2 encodes catabolic enzymes required for the oxidation of toluene and xylenes. The structural genes for these catabolic enzymes are clustered into two operons, the xylCMABN operon, which encodes a set of enzymes required for the transformation of toluene/xylenes to benzoate/toluates, and the xylXYZLTEGFJQKIH operon, which encodes a set of enzymes required for the transformation of benzoate/toluates to Krebs cycle intermediates. The latter operon can be divided physically and functionally into two parts, the xylXYZL cluster, which is involved in the transformation of benzoate/toluates to (methyl)catechols, and the xylTEGFJQKIH cluster, which is involved in the transformation of (methyl)catechols to Krebs cycle intermediates. Genes isofunctional to xylXYZL are present in Acinetobacter calcoaceticus, and constitute a benzoate-degradative pathway, while xylTEGFJQKIH homologous encoding enzymes of a methylphenol-degradative pathway and a naphthalene-degradative pathway are present on plasmid pVI150 from P. putida CF600, and on plasmid NAH7 from P. putida PpG7, respectively. Comparison of the nucleotide sequences of the xylXYZLTEGFJQKIH genes with other isofunctional genes suggested that the xylTEGFJQKIH genes on the TOL plasmid diverged from these homologues 20 to 50 million years ago, while the xylXYZL genes diverged from the A. calcoaceticus homologues 100 to 200 million years ago. In codons where amino acids are not conserved, the substitution rate in the third base was higher than that in synonymous codons. This result was interpreted as indicating that both single and multiple nucleotide substitutions contributed to the amino acid-substituting mutations, and hence to enzyme evolution. This observation seems to be general because mammalian globin genes exhibit the same tendency. 相似文献
24.
Size variation of rDNA clusters in the yeasts Saccharomyces cerevisiea and Schizosaccharomyces pombe
Summary The higher-order organization of rRNA genes was investigated in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. We used pulsed-field gel electrophoresis (PFGE) in combination with frequent cutter endonucleases having no recognition sites within rDNA repeating units to characterize tandem arrays of ribosomal genes in these two species. Large variations in rDNA cluster length were detected in various S. cerevisiae and S. pombe strains commonly used as PFGE molecular weight markers. This wide range of variability implies that the sizes currently assessed for chromosomes bearing rRNA genes in these organisms are unreliable since they may vary within strains by several hundreds of kilobase pairs, depending on the size of the tandem arrays of rRNA genes. Consequently, there is now a lack of reliable PFGE size standards between 1.6 Mb and 4.5 Mb, even when established yeast strains with calibrated chromosomes are used. 相似文献
25.
Julio Sáez-Vásquez Monique Raynal Luis Meza-Basso Michel Delseny 《Plant molecular biology》1993,23(6):1211-1221
In order to identify genes involved in cold acclimation, we have constructed a cDNA library from Brassica napus (cv. Samouraï) cold-acclimated etiolated seedlings. By differential screening, a cDNA clone named pBnC24 (Brassica napus Cold), corresponding to a new cold-inducible plant gene, was isolated. Northern blot hybridizations using total RNA from acclimated and unacclimated seedlings confirmed that BnC24 represents a cold-regulated gene. In contrast with a number of cold-inducible plant genes, BnC24 does not seem to be responsive to abscisic acid (ABA). In addition, further screening of the cold-acclimated cDNA library using pBnC24 cDNA as a probe, allowed the isolation of a second type of homologous cDNA. Sequence analysis showed that the two BnC24 genes encode basic 24 kDa proteins, which are highly hydrophilic and rich in alanine, lysine and arginine. The nucleotide and deduced amino acid sequences of these clones do not show any homology with other previously described cold-induced plants genes. However they have strong homology with a recently discovered human tumour gene, bbc1 (breast basic conserved), which seems to be highly conserved in eukaryotes. 相似文献
26.
Yannick Azou Monique Laval 《Biology of the cell / under the auspices of the European Cell Biology Organization》1993,77(2):155-164
Summary— We have previously shown the presence, in the amplified DNA of a Drosophila cell line resistant to N-phosphonacetyl-L-aspartate (PALA), of two units of 150 kb and 120 kb respectively duplicated and amplified. The two joints (J1 and J2) linking these units as well as their respective wild-type counterparts have been sequenced. Sequence analysis indicates that a region of the Drosophila genome which corresponds to the proximal boundary of the 150 kb unit is common to both joints. In addition to this common region, the J1 junction possesses a 26-nucleotide sequence belonging to the J2 junction. This indicates that the J2 junction was the first formed, and that J1, therefore, results from recombination between J2 and a region of the wild-type genome 120 kb distal to J2. Sequence analysis also reveals that the joints result from illegitimate recombination between unrelated regions. AT-rich sequences, strand bias composition and putative topoisomerase I and II sites were found in at least one of the two parental sequences involved in the formation of the joints. On the basis of these results we can hypothesize that after two illegitimate recombinations between sister chromatids, leading first to J2 and then to J1, the amplification may have arisen by a series of homologous (unequal crossing-over) or illegitimate recombinations, or by an intrachromosomal rolling circle. 相似文献
27.
Characterization of Xanthomonas campestris Pathovars by rRNA Gene Restriction Patterns 总被引:4,自引:2,他引:2 下载免费PDF全文
Yvette Berthier Valrie Verdier Jean-Luc Guesdon Danile Chevrier Jean-Baptiste Denis Guy Decoux Monique Lemattre 《Applied microbiology》1993,59(3):851-859
Genomic DNA of 191 strains of the family Pseudomonadaceae, including 187 strains of the genus Xanthomonas, was cleaved by EcoRI endonuclease. After hybridization of Southern transfer blots with 2-acetylamino-fluorene-labelled Escherichia coli 16+23S rRNA probe, 27 different patterns were obtained. The strains are clearly distinguishable at the genus, species, and pathovar levels. The variability of the rRNA gene restriction patterns was determined for four pathovars of Xanthomonas campestris species. The 16 strains of X. campestris pv. begoniae analyzed gave only one pattern. The variability of rRNA gene restriction patterns of X. campestris pv. manihotis strains could be related to ecotypes. In contrast, the variability of patterns observed for X. campestris pv. malvacearum was not correlated with pathogenicity or with the geographical origins of the strains. The highest degree of variability of DNA fingerprints was observed within X. campestris pv. dieffenbachiae, which is pathogenic to several hosts of the Araceae family. In this case, variability was related to both host plant and pathogenicity. 相似文献
28.
We have used fluorescence in situ hybridization to map the positions of the different repetitive DNA sequences from the region forming the lampbrush loop pair Nooses on the Y chromosome of Drosophila hydei. This region harbours a megabase cluster of tandemly organized repeats of the Y-specific ay1 family and a megabase cluster of tandem repeats of the related Y-specific YsI family. In addition, ay1 repeats also occur in short blocks that are interspersed by other repetitive DNA sequences that we call Y-associated, since they have additional copies on other chromosomes. Using specific probes for ay1, YsI and Y-associated DNA sequences, we show that there is one large proximal cluster of YsI repeats and one, more distally located, large cluster of ay1 repeats. The Y-chromosomal copies of the Y-associated sequences are located in the most distal part of the ay1 cluster. This is consistent with the juxtaposition of ay1 and Y-associated sequences in more than 300 kb of cloned genomic DNA. Since both ay1 and Y-associated sequences have been shown to be transcribed in the Nooses, the lampbrush loop is formed in a distal region of the short arm of the Y chromosome, adjacent to the terminally located nucleolus organizer region. The clusters of homogeneous ay1 and YsI repeats are of no functional significance for the formation of the lampbrush loop. 相似文献
29.
Iron content of sediment and phosphate adsorption properties 总被引:9,自引:2,他引:7
Phosphorus can occur in sediments in different forms and accordingly its availability varies. The distinction between the phosphorus fractions is made with two chemical extraction methods; an ammonium oxalate-oxalic acid extraction and an extraction according to Hieltjes & Lijklema (1980).The iron and aluminum liberated with the ammonium oxalate-oxalic acid extraction method is linearly correlated (r
2 = 0.73) with the phosphorus liberated in the first two steps of the Hieltjes and Lijklema extraction by: P = 0.035 (Fe + Al) + 0.001 (P, Fe and Al in mmol g–1).The iron and aluminum (hydr)oxides are very important fractions in the sediment adsorption capacity for phosphorus. The phosphorus sorption capacity (PSC) is 0.080 mol P (mol (Fe + Al))–1 and the adsorption constant (k) is 11.9 µmol P l–1. Here it is assumed that iron and aluminum (hydr)oxide have the same affinity for phosphorus. 相似文献
30.
Sandrine Villechanoux Monique Garnier Frédéric Laigret Joël Renaudin Joseph-Marie Bové 《Current microbiology》1993,26(3):161-166
We have recently cloned three DNA fragments (In-2.6, In-1.0, and In-0.6) of the noncultured, bacterial-like organism (BLO) associated with citrus greening disease. Nucleotide sequence determination has shown that fragment In-2.6 is part of therplKAJL-rpoBC gene cluster, a well-known operon in eubacteria. The DNA fragment upstream of and partially overlapping with In-2.6 could be isolated and was shown to be thenusG gene. InEscherichia coli, nusG is also immediately upstream ofrplKAJL-rpoBC. Fragment In-1.0 carries the gene for a bacteriophage type DNA polymerase. Fragment In-0.6 could not be identified.When In-2.6 was used, at high stringency, as a probe to detect greening BLO strains in infected plants, hybridization was obtained with all Asian strains tested, but not with the African strain examined. At lower stringencies, In-2.6 was able to detect also the African strain. The implications of these reults in the taxonomical position of the greening BLO are discussed. 相似文献