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1.
Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect. 相似文献
2.
Germ cell regulation of Sertoli cell transferrin mRNA levels 总被引:3,自引:0,他引:3
3.
4.
Variation in the ribosomal internal transcribed spacers (ITS1 and ITS2) among eight taxa of the Mimulus guttatus species complex 总被引:1,自引:0,他引:1
The internal transcribed spacer region (ITS1 and ITS2) of the 18S-25S
nuclear ribosomal DNA sequence and the intervening 5.8S region were
sequenced from three individuals in each of eight taxa of the Mimulus
guttatus species complex. Three discrete variants, or "types," of ITS
sequences were found, among which 30%-40% of sites differed, compared with
1%-2% within types. Dot plots indicate that these types were not related by
conspicuous rearrangements or inversions. More than one ITS type was often
found in the same taxon, and two of three ITS types span species
boundaries, indicating their presence prior to speciation. These ITS
sequences showed essentially no positional homology with the nearest
sequenced relative, tomato. In contrast, the 5.8S region was relatively
unvaried, with 8 of 162 sites varied in the sample among all eight taxa.
The phylogeny inferred by the most common ITS sequence type, rooted by the
two other ITS types, agreed with isozymes in showing the distinctness of M.
nudatus, M. laciniatus, and M. tilingii from the other five taxa.
相似文献
5.
Variation in heat shock proteins within tropical and desert species of poeciliid fishes 总被引:8,自引:0,他引:8
Norris CE; diIorio PJ; Schultz RJ; Hightower LE 《Molecular biology and evolution》1995,12(6):1048-1062
The 70-kilodalton heat shock protein (hsp70) family of molecular
chaperones, which contains both stress-inducible and normally abundant
constitutive members, is highly conserved across distantly related taxa.
Analysis of this protein family in individuals from an outbred population
of tropical topminnows, Poeciliopsis gracilis, showed that while
constitutive hsp70 family members showed no variation in protein isoforms,
inducibly synthesized hsp70 was polymorphic. Several species of
Poeciliopsis adapted to desert environments exhibited lower levels of
inducible hsp70 polymorphism than the tropical species, but constitutive
forms were identical to those in P. gracilis, as they were in the
confamilial species Gambusia affinis. These differences suggest that
inducible and constitutive members of this family are under different
evolutionary constraints and may indicate differences in their function
within the cell. Also, northern desert species of Poeciliopsis synthesize a
subset of the inducible hsp70 isoforms seen in tropical species. This
distribution supports the theory that ancestral tropical fish migrated
northward and colonized desert streams; the subsequent decrease in
variation of inducible hsp70 may have been due to genetic drift or a
consequence of adaptation to the desert environment. Higher levels of
variability were found when the 30- kilodalton heat shock protein (hsp30)
family was analyzed within different strains of two desert species of
Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In
both cases the distribution of hsp30 isoform diversity was similar to that
seen previously with allozyme polymorphisms.
相似文献
6.
T L Rankin K J Tsuruta M K Holland M D Griswold M C Orgebin-Crist 《Biology of reproduction》1992,46(5):747-766
Three murine epididymal secretory proteins have been characterized by their site of synthesis, sperm association, and tissue localization by use of polyclonal antisera and immunochemistry. Mouse epididymal protein 7 (MEP 7) was localized initially within the supranuclear regions of some principal epithelial cells in the proximal corpus while other cells remained unstained. In the mid-proximal corpus, all principal cells and stereocilia were stained, and luminal staining increased from corpus to cauda. Some clear cells in the distal corpus and cauda also showed immunoperoxidase staining. Sequential extraction of caudal spermatozoa indicated that MEP 7 was predominantly loosely associated with spermatozoa and that only a small amount of MEP 7 required detergent to extract it from spermatozoa. Examination of other rodent caudal fluids revealed a related protein in rat caudal fluid of 32 kDa, and amino acid sequence analysis of MEP 7 showed a 68% sequence similarity with rat proteins AEG and D/E. MEP 9 immunolocalized within the cytoplasm of all principal cells of the distal caput. In a transition zone between the distal caput and the corpus, some principal cells were stained while others were not. Distal to the corpus, the principal cell staining gradually decreased. In the distal caput and proximal corpus, large heavily stained droplets associated with spermatozoa were seen in the lumen. The staining intensity of these droplets also decreased from corpus to cauda. The clear cells of the distal corpus and cauda did not stain with the antibody to MEP 9. Sequential extraction of caudal spermatozoa showed that some MEP 9 was extractable under low-salt conditions, whereas extraction with 0.1% Triton X-100 was required to remove all MEP 9, indicating it was firmly associated with spermatozoa. The antibody to MEP 9 cross-reacted with a 25-kDa protein present in rat caudal fluid. MEP 10 was localized within the cytoplasm of the principal cells, the stereocilia, and the lumen of the epididymis at the junction of the distal caput and corpus. In the distal corpus, a large number of clear cells were stained, but very few of these cells stained in the cauda. MEP 10 dissociated completely from caudal spermatozoa under low-salt conditions, indicating that it was not firmly bound to spermatozoa. The antiserum to MEP 10 cross-reacted with proteins present in rat and guinea pig caudal fluid. The related rat protein migrated at approximately 20 kDa. Amino acid sequence analysis of MEP 10 revealed an 86% sequence similarity with rat proteins B and C.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
7.
ON MISSING ENTRIES IN CLADISTIC ANALYSIS 总被引:5,自引:0,他引:5
Norman I. Platnick Charles E. Griswold Jonathan A. Coddington 《Cladistics : the international journal of the Willi Hennig Society》1991,7(4):337-343
Abstract The exact algorithms of two commonly used parsimony programs, Hennig86 by J. S. Farris and PAUP by D. Swofford, sometimes produce different solutions, and sometimes produce resolutions that are not supported by the data being analysed. The discrepancies apparently involve the treatment of missing entries, which can currently represent unknown data, inapplicable character and/or polymorphic taxa. Each of those potential sources of ambiguity is logically (if not computationally) different; with regard to binary characters, unknown data could be either 0 or 1, inapplicable characters are neither 0 nor 1 and polymorphisms are both 0 and 1. Resolutions that cannot be supported by any possible combination of known state attributions should either be flagged as such or suppressed entirely. 相似文献
8.
Seminal transferrin and spermatogenic capability in the bull 总被引:3,自引:0,他引:3
The objective of this study was to determine the relationship between seminal transferrin and sperm output in ejaculates from mature dairy bulls. Caudal sperm reserves in mature Holstein bulls (n = 15) were depleted by 8 successive ejaculations during a 50-70-min period (depletion phase). Bulls were then ejaculated 6 times per week for a period of 4 weeks (6X phase). Weekly sperm output (WSO) and weekly transferrin output (WTfO) were the sums of sperm and transferrin levels in 6 ejaculates taken in 1 week of the study. Mean WSO ranged from 20.7 billion to 39.6 billion and mean WTfO ranged from 334 micrograms to 1872 micrograms among the bulls. Regression analysis of sperm and transferrin levels in ejaculates collected during the depletion phase indicated that approximately 40% of seminal transferrin was not related to sperm output and probably was from accessory fluids. A relationship between total seminal transferrin and total sperm in ejaculate was observed (p less than 0.01, r = 0.54). This relationship was stronger when the transferrin was corrected for accessory fluid contribution (p less than 0.01, r = 0.65). The relationship between WSO and WTfO corrected for accessory fluid transferrin contribution (cWTfO) was significant (p less than 0.01, r = 0.64). The relationship between WSO and cWTfO can be interpreted to reflect the relationship between actual testicular sperm production and transferrin from testicular or epididymal origin. 相似文献
9.
Sertoli cell cultures were prepared from the testes of 20-day-old rats. The proteins which were secreted by the cells into the culture medium were labeled with [3H]leucine or l-[3H]fucose. The proteins were concentrated by ultrafiltration and analysed by polyacrylamide slab gel electrophoresis (PAGE) in the presence of sodium dodecyl sulfate (SDS). Autofluorography of the gels at ?70 °C showed that the rat Sertoli cells synthesized and secreted at least 7 major polypeptides. The polypeptides had molecular weights ranging from 16 000 to 140 000 D. Proteins which were secreted from cultures of testicular fibroblasts and myoid cells had electrophoretic properties on SDS-PAGE which were different from Sertoli cell secreted proteins. Addition of FSH and testosterone to the Sertoli cell cultures increased the total synthesis and secretion of [3H]leucine-labeled proteins. No qualitative changes in the proteins as a result of hormone application could be detected. However, the synthesis of a polypeptide of molecular weight 48 000 was increased relative to the other secreted peptides if the cells were maintained in FSH and testosterone. The Sertoli cell secreted proteins were shown to be glycoproteins which can bind to ConA-Sepharose and can be labeled with [3H]fucose. Tunicamycin, a specific inhibitor of N-glycosylation, inhibited the secretion of [3H]proteins by 50% but had little effect on the intracellular protein synthesis. 相似文献
10.
Christina A. Muzny Imran R. Sunesara Ranjit Kumar Leandro A. Mena Michael E. Griswold David H. Martin Elliot J. Lefkowitz Jane R. Schwebke 《PloS one》2013,8(11)