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排序方式: 共有163条查询结果,搜索用时 15 毫秒
101.
J M Gee W M Amselgruber B Jasani R I Nicholson 《The journal of histochemistry and cytochemistry》1991,39(12):1659-1670
To date, reliable and sensitive methods to localize the estrogen receptor (ER) in rat tissues and human breast cancers have required the use of frozen sections. This not only incurs poor tissue structure but also precludes the study of small breast lesions that are usually paraffin embedded for histological evaluation. We have developed and optimized a dinitrophenyl hapten sandwich staining (DHSS) immunocytochemical procedure to demonstrate ER in paraffin-embedded, hormone-sensitive tissues of the rat and in human breast cancers. The method was applicable to formalin- and Bouins-fixed material, with trypsinization of sections being essential. The immunocytochemical system utilized a dinitrophenyl (DNP) hapten-labeled monoclonal antibody to the receptor. Mouse IgM anti-DNP was used secondarily, followed by a DNP/peroxidase complex, diaminobenzidine/hydrogen peroxide chromogen, and silver intensification. This highly sensitive method localized the ER within paraffin-embedded rat uterus, fallopian tube, vagina, and normal and cancerous mammary gland. Furthermore, excellent staining was generated in human breast cancers in accordance with their ER-ICA status. Control sections involving simultaneous incubation with DNP-labeled and unlabeled H222 were background free, while uteri from castrated rats demonstrated reduced receptor immunostaining. Staining was also absent in ER-negative human breast tumors. 相似文献
102.
Libia Sanz Juan Jos Calvete Karlheinz Mann Wolfram Schfer Erich R. Schmid Werner Amselgruber Fred Sinowatz Michael Ehrhard Edda Tpfer-Petersen 《FEBS letters》1992,300(3):213-218
AWN is a boar protein which originates in secretions of the male accessory glands and which becomes sperm surface-associated upon ejaculation. It is one of the components thought to mediate sperm adhesion to the egg's zona pellucida through a carbohydrate-recognition mechanism. AWN may, thus, participate in the initial events of fertilization in the pig. In this report we describe its complete primary structure by combination of protein-chemical and mass spectrometric methods. AWN exists as two isoforms, AWN-1 and AWN-2, which differ in that AWN-2 is N-terminally acetylated. The amino acid sequence of AWN contains 133 amino acid residues and two disulphide bridges between nearest-neighbour cysteine residues. Analysis of the amino acid sequence of the AWN proteins showed significant similarity only to AQN-1 and AQN-3, two other boar spermadhesins. 相似文献
103.
The conclusion arrived at by chemical methods, that the volatile agent produced when sulphur is applied to a heated surface is gaseous sulphur, has been subjected to biological tests in which the fungi Ery-siphe graminis and Sphaerotheca Humulind the gall mite Eriophyes ribis were employed.
The fungi were found not to be sufficiently sensitive to yield satisfactory and concordant results and strong support is given to the view that actual contact of the sulphur particle with the fungus is necessary before fungicidal action can occur.
It was shown that the agent present in air passed over heated sulphur and responsible for the death of the gall mite was not removed by filtration through a heated glass-wool plug, this observation being contrary to the view that the toxic agent is produced initially in solid form.
Filtration through a cooled glass-wool plug only removed part of the volatile agent and it was shown that the gall mite is affected by the traces of sulphur volatilised at ordinary temperatures.
The results of the experiments with the gall mite were in complete accord with those obtained in the previous chemical work.
At relatively large concentrations sulphur dioxide and hydrogen sulphide are without permanent effect upon the gall mite and these gases are therefore not responsible for the acaricidal action of sulphur. 相似文献
The fungi were found not to be sufficiently sensitive to yield satisfactory and concordant results and strong support is given to the view that actual contact of the sulphur particle with the fungus is necessary before fungicidal action can occur.
It was shown that the agent present in air passed over heated sulphur and responsible for the death of the gall mite was not removed by filtration through a heated glass-wool plug, this observation being contrary to the view that the toxic agent is produced initially in solid form.
Filtration through a cooled glass-wool plug only removed part of the volatile agent and it was shown that the gall mite is affected by the traces of sulphur volatilised at ordinary temperatures.
The results of the experiments with the gall mite were in complete accord with those obtained in the previous chemical work.
At relatively large concentrations sulphur dioxide and hydrogen sulphide are without permanent effect upon the gall mite and these gases are therefore not responsible for the acaricidal action of sulphur. 相似文献
104.
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107.
Phylogenetic inference under the pure drift model 总被引:1,自引:1,他引:0
When pairwise genetic distances are used for phylogenetic reconstruction,
it is usually assumed that the genetic distance between two taxa contains
information about the time after the two taxa diverged. As a result, upon
an appropriate transformation if necessary, the distance usually can be
fitted to a linear model such that it is expressed as the sum of lengths of
all branches that connect the two taxa in a given phylogeny. This kind of
distance is referred to as "additive distance." For a phylogenetic tree
exclusively driven by random genetic drift, genetic distances related to
coancestry coefficients (theta XY) between any two taxa are more suitable.
However, these distances are fundamentally different from the additive
distance in that coancestry does not contain any information about the time
after two taxa split from a common ancestral population; instead, it
reflects the time before the two taxa diverged. In other words, the
magnitude of theta XY provides information about how long the two taxa
share the same evolutionary pathways. The fundamental difference between
the two kinds of distances has led to a different algorithm of evaluating
phylogenetic trees when theta XY and related distance measures are used.
Here we present the new algorithm using the ordinary- least-squares
approach but fitting to a different linear model. This treatment allows
genetic variation within a taxon to be included in the model. Monte Carlo
simulation for a rooted phylogeny of four taxa has verified the efficacy
and consistency of the new method. Application of the method to human
population was demonstrated.
相似文献
108.
Previous investigations on the monkey kidney COS cell line demonstrated the
weak expression of fucosylated cell surface antigens and presence of
endogenous fucosyltransferase activities in cell extracts. RT-PCR analyses
have now revealed expression of five homologs of human fucosyltransferase
genes, FUT1, FUT4, FUT5, FUT7, and FUT8, in COS cell mRNA. The enzyme in
COS cell extracts acting on unsialylated Type 2 structures is closely
similar in its properties to the alpha1,3- fucosyltransferase encoded by
human FUT4 gene and does not resemble the product of the FUT5 gene.
Although FUT1 is expressed in the COS cell mRNA, it has not been possible
to demonstrate alpha1,2- fucosyltransferase activity in cell extracts but
the presence of Le(y) and blood-group A antigenic determinants on the cell
surface imply the formation of H-precursor structures at some stage. The
most strongly expressed fucosyltransferase in the COS cells is the
alpha1,6-enzyme transferring fucose to the innermost N -acetylglucosamine
unit in N - glycan chains; this enzyme is similar in its properties to the
product of the human FUT8 gene. The enzymes resembling the human FUT4 and
FUT8 gene products both had pH optima of 7.0 and were resistant to 10 mM
NEM. The incorporation of fucose into asialo-fetuin was optimal at 5.5 and
was inhibited by 10 mM NEM. This result initially suggested the presence of
a third fucosyltransferase expressed in the COS cells but we have now shown
that triantennary N- glycans with terminal nonreducing galactose units,
similar to those present in asialo-fetuin, are modified by a weak
endogenous beta-galactosidase in the COS cell extracts and thereby rendered
suitable substrates for the alpha1,6- fucosyltransferase.
相似文献
109.
110.
Although the reproductive ecology of marine turtles has beenthe subject of numerous long-range studies, the reproductivephysiology of these unique animals is little known. Recently,however, preliminary anatomical and endocrinological studieshave provided a good basis on which to begin to attempt to explainseveral of their unusual biological systems. New findings relatedto the anatomy of Chelonia mydas and Lepidochelys olivacea arepresented. The female, although having a very massive pair ofsimultaneously functioning ovaries, appears in most ways verysimilar to other chelonians. Corpora hemorrhagica, corpora luteaand corpora atretica from active ovaries are briefly described.Ovulation coincides with a luteinizing hormone and progesteronesurge. Sperm are probably stored for the season after a singlemating period which appears to occur prior to the first ovulation.Males may also cycle and mating as well as nesting are seenas more or less seasonal. The seasonality could be controlledin part by melatonin or other endocrines from the sea turtle'smassive pineal complex. A hypothetical model for reproductionis presented in hopes of stimulating interest in physiologicalapproaches to the study of marine turtle reproduction. 相似文献