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排序方式: 共有75条查询结果,搜索用时 15 毫秒
1.
J Borst E de Vries H Spits J E de Vries A W Boylston E A Matthews 《Journal of immunology (Baltimore, Md. : 1950)》1987,139(6):1952-1959
Three monoclonal antibodies react with the T cell receptor on the tumor line HPB-ALL and in addition with 3 to 13% of human peripheral blood T cells of normal donors. These antibodies are shown to react with an epitope encoded by the V beta 5 family of T cell receptor beta-chain variable region gene segments. Cells expressing V beta 5 gene segments can have cytotoxic or helper function, be of the T4+ or T8+ phenotype, and have specificity for either class I or class II major histocompatibility complex alloantigens. Seven T cell clones were generated, which express V beta 5 and are specific for the HLA-A2 molecule. With the use of these clones, we illustrate how isoelectric focusing can be used to analyze T cell receptor alpha- and beta-chain structure. The seven clones recognize five distinct conformational determinants on HLA-A2. They procure different binding sites by the use of different alpha-chains, J beta sequences, or both. 相似文献
2.
ELENA RAEVSKAYA MARCO VECOLI WIESAW BEDNARCZYK MARCO TONGIORGI 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2004,37(1):97-111
Billingen (Lower Arenig/Lower Ordovician) sediments of the St. Petersburg region, northwest Russia and the Leba area, northern Poland of the East European Craton yield acritarch assemblages, which are largely homogenous though displaying minor compositional differences that probably reflect a gradient from inner to outer shelf environments. Comparison with coeval acritarch microflora from the Yangtze Platform, South China, shows an overall similarity between Baltoscandian and South Chinese phytoplankton. The widespread uniformity in the fossil microphytoplankton may be related to the extensive global 'evae' sea-level transgression, which characterized the Billingen time. This suggests that during the Tremadoc through early Arenig times, acritarch assemblages displayed essentially an undifferentiated cold-water and oceanic character along the whole margin of Perigondwana in the South, as well as on the South Chinese and Baltic platforms, at middle latitudes (Mediterranean oceanic Realm). Despite this overall similarity, however, some typical taxa of the high-latitude Mediterranean Province (Arbusculidium, Coryphidium and Striatotheca) occur in South China, but are absent in Baltica. This discrepancy is explained as caused by differences in climatic and physiographic conditions that prevailed at the two palaeocontinents at this time. The inferred pattern of oceanic circulation during the Lower Ordovician is consistent with the palynological evidence of a prevailing warmer climate in Baltica than in South China, although the two palaeocontinents occupied the same palaeolatitudinal position. 相似文献
3.
Choksi KB Nuss JE Boylston WH Rabek JP Papaconstantinou J 《Free radical biology & medicine》2007,43(10):1423-1438
Mitochondrial dysfunction generates reactive oxygen species (ROS) which damage essential macromolecules. Oxidative modification of proteins, DNA, and lipids has been implicated as a major causal factor in the age-associated decline in tissue function. Mitochondrial electron transport chain complexes I and III are the principal sites of ROS production, and oxidative modifications to the complex subunits inhibit their in vitro activity. Therefore, we hypothesize that mitochondrial complex subunits may be primary targets for oxidative damage by ROS which may impair normal complex activity by altering their structure/function leading to mitochondrial dysfunction associated with aging. This study of kidney mitochondria from young, middle-aged, and old mice reveals that there are functional decreases in complexes I, II, IV, and V between aged compared to young kidney mitochondria and these functional declines directly correlate with increased oxidative modification to particular complex subunits. We postulate that the electron leakage from complexes causes specific damage to their subunits and increased ROS generation as oxidative damage accumulates, leading to further mitochondrial dysfunction, a cyclical process that underlies the progressive decline in physiologic function seen in aged mouse kidney. In conclusion, increasing mitochondrial dysfunction may play a key role in the age-associated decline in tissue function. 相似文献
4.
A W Boylston J Borst H Yssel D Blanchard H Spits J E de Vries 《Journal of immunology (Baltimore, Md. : 1950)》1986,137(2):741-744
Five Mab raised against the T cell antigen receptor of the human T cell line HPB-ALL which react with a subpopulation of normal peripheral blood T cells are described. Three Mab, 3D6, 1C1, and 1C2, react with 3 to 5% of normal PBL and stimulate proliferation of the cells with which they react. An increase in the number of cells which react with all five Mab occurs. Two Mab, 2D4 and 65, react with subsets of the cells which bind 1C1, 1C2, and 3D6 and divide the family into four subgroups, 2D4+ 65+, 2D4+ 65-, 2D4- 65+, and 2D4- 65-. Functional T cell clones in all four subfamilies have been observed. Cytolytic function can be correlated with the TcR phenotype expressed because all of the Mab which react with a particular clone inhibit its ability to lyse a specific target. The epitopes recognized by the panel are closely related because all five block each other's binding to HPB-ALL. In addition, the determinants recognized by 3D6, 1C1, and 1C2 on normal lymphocytes are probably very closely related because all clones examined react with all three Mab. 相似文献
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MARCIN SIELEZNIEW ROBERT RUTKOWSKI DONATA PONIKWICKA‐TYSZKO MIROSAW RATKIEWICZ IZABELA DZIEKASKA GIEDRIUS VITRA 《Insect Conservation and Diversity》2012,5(3):223-236
Abstract. 1. The endangered butterfly Phengaris alcon exists in two ecotypes (P. ‘alcon’ and P. ‘rebeli’), which inhabit contrasting biotopes (wet and warm/dry grasslands respectively) and use different larval food plants. The initially flower‐bud‐feeding caterpillars complete their development as social parasites of Myrmica ants, and the specificity of these relationships shows geographical variation. 2. We studied the genetic structure of 16 populations (365 individuals) of both ecotypes in eastern Europe, sampling P. ‘rebeli’ in two disjunct areas in Lithuania and southern Poland, and P. ‘alcon’ on Polish localities between them. We analysed the cytochrome c oxidase subunit I (COI) mitochondrial gene, the EF1‐α nuclear gene and five polymorphic microsatellite loci. 3. All individuals shared an identical COI haplotype, which we hypothesise may be linked to a selective sweep associated with the presence of the Wolbachia B strain in all populations. 4. For nuclear markers, we did not find a clear pattern reflecting division into two putative ecotypes. However, ecotypes differed significantly in their genetic variability, i.e., the P. ‘rebeli’ ecotype was less polymorphic, and its populations were much more differentiated (FST: 0.632 for EF1‐α and 0.504 for microsatellites) than the P. ‘alcon’ ecotype (0.177 and 0.082, respectively). 5. Our microsatellite data suggest that all populations of P. ‘alcon’ form a single clade but that P ‘rebeli’ can be split into either six or two clades. The former model would indicate many independent origins, especially in the mountainous areas of southern Poland. The latter, not mutually exclusive, grouping clearly reflects the use of different host ants. 相似文献
7.
A quick embedding method employing UV polymerization reactions has been devised for embedding fibers in acrylic and meth-acrylate media. The resultant thin, flat embed-dings are suitable for both light and electron microscopy. 相似文献
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9.
Abstract: A systematic account of highly diverse cyrtocrinid faunules from Upper Jurassic strata of ?tramberk type (Oxfordian–Tithonian) in southern Poland (Polish Carpathians) is presented. Fourteen taxa (Phyllocrinus malbosianus, Ph. stellaris, Ph. sp., Psalidocrinus armatus, Sclerocrinus compressus, S. polonicus sp. nov., Hemicrinus aff. kabanovi, Ancepsicrinus parvus gen. et sp. nov., Tetracrinus baumilleri sp. nov., Eugeniacrinites alexandrowiczi, E. cf. moravicus, E. sp., Eudesicrinus gluchowskii sp. nov. and Hemibrachiocrinus tithonicus sp. nov. are described and illustrated. Representatives of the genus Eudesicrinus, previously recorded only from the Lower Jurassic, are here shown to extend into the uppermost Jurassic. Other cyrtocrinids considered are common in Jurassic/Cretaceous strata across Europe. In the present faunules, isocrinid (Isocrinida), comatulid (Comatulida) and roveacrinid (Roveacrinida sensu Rasmussen, inclusive of Saccocoma) crinoids are associated. 相似文献