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51.
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Zusammenfassung Das Pankreas und der Fettkörper von Latimeria chalumnae, dem einzigen rezenten Crossopterygier aus der Klasse der Coelacanthes, werden in ihrer Lagebeziehung zu Magen, Darm und Milz beschrieben. Das von Millot und Anthony (1958) als Pankreas geschilderte Organ wird histologisch als Fettkörper identifiziert. Der exokrine Pankreasanteil besteht, ähnlich wie bei anderen niederen Wirbeltieren, aus einem tubulösen System exkretorischer Zellen. Das Inselorgan ist mit dem Gangsystem verbunden. Mit der Aldehydfuchsin Ponceau de Xylidine-Färbung lassen sich A- und B-Zellen, mit der Versilberung nach Hellman und Hellerström (1960) Silberzellen darstellen. Geschwollene Zellen werden als Fixationsartefakt nach Formolfixierung betrachtet. B-Zellknospen an den Gängen werden als erste phylogenetische Ansätze zu einer Dissemination des Inselorgans in das exokrine Parenchym hinein gedeutet. Zellen zwischen den exokrinen Tubuli werden beschrieben. Die Befunde werden mit den Ergebnissen am Pankreas niederer Wirbeltiere und Säuger verglichen.
Summary The topographical anatomy of the pancreas and the fat-body of Latimeria chalumnae, the only living Crossopterygian of the suborder of Coelacanths, is described. The organ, which was considered by Millot and Anthony (1958) to be the pancreas, has been histologically identified as a fat-body. The exocrine part of the pancreas consists of a tubulous system of exocrine cells, which are similar to those of lower vertebrates. The islet-organ is connected to the ductsystem. The aldehydfuchsin Ponceau de Xylidine-staining makes it possible to demonstrate - and -cells, the argyrophil reaction according to Hellman and Hellerström (1960) silvercells. Swollen cells are thought to be fixation artefacts due to formalin-fixation. -cellbuds, which are attached to the ducts, are regarded as the first phylogenetic beginning of dissemination of the islet-organ into the exocrine tissue. Cells between the exocrine tubules are described. The findings are compared with the results of the investigations of the pancreas of lower vertebrates and mammals.


Herrn Dr. G. v. Wahlert, Forschungsstelle für Ichthylogie in Ludwigsburg, danke ich für die freundliche Überlassung des Untersuchungsmaterials.  相似文献   
53.
We investigated the spatial expression of three genes that are expressed during seed germination and postgerminative development in Brassica napus L. using in situ hybridization procedures. Two of the mRNAs encode isocitrate lyase and a predicted polypeptide that is homologous to cysteine proteinases. We reported previously that the mRNAs are prevalent primarily in cotyledons of seedlings and accumulate with similar kinetics during postgerminative growth. Here, we show that the two mRNAs are detected in several seedling tissues, but they display different distribution patterns in both cotyledons and root-shoot axes. The third mRNA is abundant in seedling axes and accumulates specifically in the ground meristem and mature cortex of hypocotyls and roots. Distribution of the mRNA in root meristems suggests that the gene product participates in an early event in cortical cell differentiation. Our results provide insight into the physiological processes that characterize seedlings.  相似文献   
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The pseudanthia ofHeliopsis scabra andRudbeckia vulgaris (Asteraceae) were examined during the anthesis for differences in their UV patterns. Distinct changes in the reflectance and absorbance properties could be observed. The results suggest a close correlation between different stages of floral development and pollinator attraction.
Herrn Prof. Dr.Lothar Geitler zum 90. Geburtstag gewidmet.  相似文献   
56.
The loading of amino acids and nitrate into the xylem was investigated by collection and analysis of root-pressure exudate from the cut hypocotyl stumps of seedlings of Ricinus communis L. Glutamine was found to be the dominant amino acid in the exudate and also to be the amino acid which is transferred to the xylem most rapidly and accumulated to the greatest extent. The comparison between uptake and xylem loading showed significant differences in specificity between these two transport reactions, indicating a different set of transport systems. Nitrate is transferred to the xylem at a higher relative rate than any amino acid despite the great nitrate-storage capacity of the root system. Thus the supply of nitrate to Ricinus plants leads to enhanced nitrogen allocation to the shoots.  相似文献   
57.
The intestinal tumor multiplicity in mice heterozygous for Apc(Min) is strongly modulated by genetic background. On the sensitive C57BL/6J (B6) background, mice develop large numbers of intestinal adenomas. The AKR/J (AKR) strain carries alleles that correlate with a strong reduction in tumor multiplicity. To study the effect of one of these modifiers, Mom1, we have generated a mouse line in which the AKR allele of Mom1 is carried on the sensitive B6 genetic background. This strain was produced by using a marker-assisted selection method to eliminate unlinked AKR alleles more rapidly. The application and efficiency of this method are discussed. We used this strain to determine that Mom1 affects both tumor multiplicity and tumor size in a semi-dominant fashion.  相似文献   
58.
A polyclonal antiserum against saxitoxin (STX) was used in a competitive enzyme immunoassay for the detection of paralytic shellfish poisoning toxins. The extent of cross-reactions was determined from the amounts of neoSTX, decarbamoylSTX and gonyautoxin 2/3 (GTX2/3) that gave 50% inhibition in the assay. Horseradish peroxidase (HRP) conjugates of the toxins and a bovine serum albumin conjugate of STX (STX-BSA) were used. When compared with STX-BSA and STX as standard, the extent varied to which heterologous conjugates affected the binding values of the other toxins to the antibodies. The antibodies did not bind GTX2/3-HRP. By use of neoSTX-HRP or decarbamoylSTX-HRP as the labelled antigen instead of STX-HRP, the detection limit for neoSTX was improved to 100 pg ml-1.  相似文献   
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The cultural reproduction of lithic technology, long an implicit assumption of archaeological theories, has garnered increasing attention over the past decades. Major debates ranging from the origins of the human culture capacity to the interpretation of spatiotemporal patterning now make explicit reference to social learning mechanisms and cultural evolutionary dynamics. This burgeoning literature has produced important insights and methodological innovations. However, this rapid growth has sometimes led to confusion and controversy due to an under-examination of underlying theoretical and methodological assumptions. The time is thus ripe for a critical assessment of progress in the study of the cultural reproduction of lithic technology. Here we review recent work addressing the evolutionary origins of human culture and the meaning of artifact variation at both intrasite and intersite levels. We propose that further progress will require a more extended and context-specific evolutionary approach to address the complexity of real-world cultural reproduction.  相似文献   
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