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381.
SERGIO VARGAS DIRK ERPENBECK CHRISTIAN G
CKE KATHRYN A. HALL JOHN N. A. HOOPER DORTE JANUSSEN GERT W
RHEIDE 《Zoologica scripta》2013,42(1):106-116
Vargas, S., Erpenbeck, D., Göcke, C., Hall, K. A., Hooper, J. N. A., Janussen, D. & Wörheide, G. (2012) Molecular phylogeny of Abyssocladia (Cladorhizidae: Poecilosclerida) and Phelloderma (Phellodermidae: Poecilosclerida) suggests a diversification of chelae microscleres in cladorhizid sponges. —Zoologica Scripta, 42, 106–116. The taxonomic placement of Abyssocladia Lévi, 1964 (Poecilosclerida) is controversial, having been assigned at various times to three different families (Mycalidae, Cladorhizidae and Phellodermidae) in two different suborders (Mycalina and Myxillina, respectively), since its inception in 1964. It shares the general body plan with the carnivorous sponge family Cladorhizidae (Mycalina), including the lack of an aquiferous system. Nevertheless, it also has chela spicules apparently identical to those in Phelloderma Ridley & Dendy 1886 (Phellodermidae, Myxillina). The ongoing debate on the position of Abyssocladia ultimately reduces to a discussion on the use of chelae morphology to infer phylogenetic relationships within Poecilosclerida. Here, we infer the phylogenetic relationships of the genera Phelloderma and Abyssocladia using two independent molecular markers (28S rDNA and COI), showing that Abyssocladia is not closely related to Phelloderma and belongs in Cladorhizidae. We suggest that despite their complexity, chelae morphology can evolve independently in different poecilosclerid lineages and as such might be potentially misleading as indicator of the phylogenetic history of the group. We also provide the first phylogenetic analysis of the carnivorous sponge family Cladorhizidae and give first insights into the evolution of this feeding mode in Poecilosclerida and, more generally, in Porifera. 相似文献
382.
1. In isolation of total ribosomes from Phaseolus leaves thehighest yield was obtained with an extraction medium containingHEPES buffer, low Mg2+-concentration (1 mM) and SH-group protectingagents. 2. Chloroplast and cytoplasmic ribosomes were obtained in aratio of 1 : 28 after selective isolation. 3. After freezing identical portions of cytoplasmic extractthe amount of ribosomes/ml extract dropped, but later increasedwith freezing time. 4. Ribosomal preparations showed UV-absorption spectra typicalfor RNA. Extinction ratios suggested that preparations werecontaminated with extraneous protein to a certain extent, purityincreasing after selective isolation, especially after freezing. 5. Protein patterns and sedimentation behaviour of cytoplasmicribosomes were identical regardless of addition or omissionof detergent in leaf exeracts. 6. After polyacrylamide gel electrophoresis of ribosomal proteins,29 bands of basic protein were found in cytoplasmic ribosomesand 22 in chloroplast ribosomes. Acidic proteins could not bedetected. Patterns in both extracts were different and highlyreproducible, resembling those recently reported. Tests forfive enzymes, highly active in the leaf tissue, gave negativeresults on the isolated ribosomal proteins.
1Present address: Max Planck Institut für ExperimentelleMedizin, Arb.-Gr. Biochemie, D-34 Göttingen, Hermann-Rein-Straße3, West Germany. (Received August 10, 1968; ) 相似文献
383.
ROLAND SCHULTHEIß THOMAS WILKE ASLAK JØRGENSEN CHRISTIAN ALBRECHT 《Biological journal of the Linnean Society. Linnean Society of London》2011,102(1):130-143
Changes in habitat stability may significantly shape evolutionary patterns and processes in ancient lakes. In the present study, we use a hierarchical combination of molecular phylogenetic and coalescent approaches to investigate the evolutionary history of the endemic species of the gastropod genus Bellamya in the African rift‐lake Malawi. By integrating our findings with reported palaeontological and palaeolimnological data, we demonstrate that all but one evolutionary lineage of the Pliocene Bellamya fauna in Lake Malawi became extinct. Coalescent analyses indicate that the modern radiation underwent both a sudden demographic and a spatial expansion after a genetic bottleneck. We argue that a reflooding of the lake after severe Pleistocene low stands offers a straightforward explanation for this pattern and may have triggered speciation processes in the modern endemic Bellamya radiation in Lake Malawi. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 130–143. 相似文献
384.
Cytological evolution and DNA synthesis activity of the female pronucleus were analyzed in experimentally activated virgin eggs of Pleurodeles. Pricking with a micropipette is a positive treatment for activation comparable to electric shock. As in normally fertilized eggs, the evolution of a female pronucleus is related to normal DNA synthesis. Thus, the fact that the female gametic nucleus does not achieve the first mitotic cycle, at the end of migration, cannot be related to initial failure of DNA synthesis. Normal mitoses of this nucleus are obtained in an activated egg in which development is insured by grafting a somatic nucleus. These results are discussed in terms of activation factors. 相似文献
385.
JEAN-FRANCOIS BRUGERE EMMANUEL CORNILLOT THIERRY BOURBON GUY METENIER CHRISTIAN P. VIVARÈS 《The Journal of eukaryotic microbiology》2001,48(S1):50s-55s
ABSTRACT. We applied a two-dimensional pulsed-field gel electrophoresis procedure to the genomes of two karyotype variants assigned to two different strains of the microsporidian Encephalitozoon cuniculi , termed D (strain III) and F (strain II). Data obtained for Bss HII and Mlul restriction fragment length polymorphisms in each chromosome are compiled and compared to the reference strain I variant A. Six Insertion/Deletion (InDels) are found in subterminal position, some of these being characteristic of either D or F. Like in strain I, the terminal fragments extending between each telomere and rDNA locus are conserved in length for each chromosome. They are however smaller than in reference variant. This size reduction is estimated to be 2.5 kbp for the strain III isolate and 3.5 kbp for the strain II isolate. We hypothesize that for the three E. cuniculi strains, all chromosome extremities are prone to a constant process of sequence homogenization through mitolic recombination between conserved regions. 相似文献
386.
387.
388.
Frank's family of bivariate distributions 总被引:4,自引:0,他引:4
389.
KEIKO NAKAZAWA HISAYOSHI NAKAZAWA MICHELLE BONNARD ODILE DAMOUR CHRISTIAN COLLOMBEL 《Pigment cell & melanoma research》1995,8(5):255-262
Direct cell-cell contact between melanocytes and keratinocytes has been shown to play an important role in the regulation of human melanocyte function and skin pigmentation. An important role for the calcium-dependent epithelium-specific cell adhesion molecule, E-cadherin, in melanocyte-keratinocyte adhesion was suggested previously. To further clarify regulation of E-cadherin-mediated melanocyte-keratinocyte interactions, we investigated the effects of physiological (Ca2+) and environmental (ultraviolet B [UVB] radiation) stimuli on the expression and functional activity of E-cadherin in melanocyte-keratinocyte adhesion. Expression of E-cadherin mRNA was detected by Northern blot analysis in cultured normal human melanocytes at levels similar to those in keratinocytes. Flow cytometry analysis with anti-human and anti-mouse-E-cadherin antibodies (anti-uvomorulin and ECCD-2) showed that cultured normal human keratinocytes, melanocytes, and two metastatic melanoma cell lines express E-cadherin strongly on the cell surfaces. Melanocyte adhesion, particularly to differentiating keratinocytes (cultured in 1.2 mM calcium) but not to proliferating keratinocytes or to fibroblasts, was decreased by 41.7 ± 4.5% in the absence of 1 mM Ca2+ during the binding assay. Addition of anti-mouse-E-cadherin antibody (ECCD-1) to the binding assay inhibited the adhesion of melanocytes to differentiating keratinocytes by 88.2 ± 1.1%, while addition of anti-P-cadherin antibody (PCD-1) had no effect. The levels of E-cadherin expression in melanocytes were not changed by the presence of calcium (1 mM) in the medium or by UVB irradiation (20 mJ/cm2) for one day before flow cytometry analysis. Moreover, these treatments had no effect on melanocyte-keratinocyte adhesion. These results demonstrate that E-cadherin is strongly involved in melanocyte adhesion to keratinocytes and suggest the implication of E-cadherin in the overall regulation of the skin pigmentary system. 相似文献
390.
Lichen physiology and air pollution 总被引:1,自引:1,他引:0
CHRISTOPH VON ARB CHRISTINE MUELLER KLAUS AMMANN CHRISTIAN BRUNOLD 《The New phytologist》1990,115(3):431-437