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排序方式: 共有121条查询结果,搜索用时 15 毫秒
1.
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
2.
Several molecular maps have been constructed in sorghum (Sorghum bicolor L. Moench) using a variety of probes from different grass species such as sorghum, maize, sugarcane, rice, oat, and barley. In order to enhance the utility of the existing mapping information by the sorghum research community, alignment and integration of all major molecular maps is necessary. To achieve this objective, a genetic map of 214 loci with a total map distance of 1200 cM was constructed using 98 F7 sorghum recombinant inbred lines (RILs) from a cross between two inbred lines, B35 and Tx7000. Few cDNA clones of sorghum and maize related to photosynthesis and drought stress were mapped on this map for the first time. Five major restriction fragment length polymorphism (RFLP) maps independently developed in this species were used for alignment purpose. The distributions of previously mapped markers were compared with their respective sorghum maps to align each of the linkage groups. In general, consistent linear order among markers was maintained in all the linkage maps. The successful alignment of these RFLP maps will now allow selection of a large number of markers for any region of the sorghum genome with many potential applications ranging from fine mapping and marker-assisted selection to map-based cloning for the improvement of sorghum and related species. 相似文献
3.
Subudhi PK Parami NP Harrison SA Materne MD Murphy JP Nash D 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,111(8):1632-1641
Uniola paniculata, commonly known as sea oats, is a C4 perennial grass capable of stabilizing sand dunes. It is most abundant along the Gulf of Mexico and southeastern Atlantic
coastal regions of the United States. The species exhibits low seed set and low rates of germination and seedling emergence,
and so extensive clonal reproduction is achieved through production of rhizomes, which may contribute to a decline in genetic
diversity. To date, there has been no systematic assessment of genetic variability and population structure in naturally occurring
stands in the USA. This study was conducted to assess the genetic relationship and diversity among nineteen U. paniculata accessions representing eight states: Texas, Louisiana, Mississippi, Alabama, Florida, South Carolina, North Carolina, and
Virginia, using amplified fragment length polymorphism (AFLP). Twelve AFLP EcoRI+MseI primer combinations generated a wide range of polymorphisms (42–81%) with a mean of 59%. Overall, the sea oats plants exhibited
a low range of genetic similarity. Florida accessions, FL-33 and FL-39, were most genetically diverse and the accessions from
both Carolinas and Virginia (NC-1, NC-11, SC-15, and VA-53) harbored less genetic variability. Cluster analysis using the
UPGMA approach separated U. paniculata plants into four major clusters which were also confirmed by principal coordinate analysis (PCO). Further examination of
the different components of genetic variation by analysis of molecular variance (AMOVA) indicated the largest proportion of
variability at the state level (47.8%) followed by the variation due to the differences among the genotypes within an accession
(34.4%), and the differences among the accessions within a state (17.8%). The relationship between genetic diversity and geographic
source of sea oats populations of the United States as revealed through this comprehensive study will be helpful to resource
managers and commercial nurseries in identifying suitable plant materials for restoration of new areas without compromising
the adaptation and genetic diversity. 相似文献
4.
5.
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
6.
Administration of agonistic anti-4-1BB monoclonal antibody leads to the amelioration of experimental autoimmune encephalomyelitis. 总被引:15,自引:0,他引:15
Yonglian Sun Xiaoqi Lin Helen M Chen Qiang Wu Sumit K Subudhi Lieping Chen Yang-Xin Fu 《Journal of immunology (Baltimore, Md. : 1950)》2002,168(3):1457-1465
4-1BB, a member of the TNFR superfamily, is a costimulatory receptor primarily expressed on activated T cells. It has been shown that the administration of agonistic anti-4-1BB Abs enhances tumor immunity and allogenic immune responses. Paradoxically, we found that the administration of an agonistic anti-4-1BB mAb (2A) dramatically reduced the incidence and severity of experimental autoimmune encephalomyelitis (EAE). Adoptive transfer of T cells from such treated mice failed to induce EAE, whereas anti-4-1BB treatment following adoptive transfer of encephalitogenic T cells did not prevent EAE pathogenesis. These results suggest that anti-4-1BB treatment during the induction phase inhibits autoreactive T cell immune responses rather than preventing T cell trafficking into the CNS. This was substantiated by the observations that draining lymph node cells from anti-4-1BB-treated mice failed to respond to Ag stimulation in vitro. In addition, we found that such treatment initially promotes the activation and proliferation of Ag-specific CD4+ T cells but subsequently increases their probability of undergoing activation-induced cell death, thereby inhibiting effector T cell responses. More importantly, 2A treatment also inhibits the relapse of EAE in a clinically relevant murine model of multiple sclerosis. This study indicates that the agonistic Ab against 4-1BB can potentially be used as a novel immunotherapeutic agent for treating autoimmune diseases. 相似文献
7.
Costimulatory molecule-targeted antibody therapy of a spontaneous autoimmune disease 总被引:19,自引:0,他引:19
Humans and mice deficient in Fas, a tumor necrosis factor (TNF)-receptor family member, cannot induce apoptosis of autoreactive cells, and consequently develop progressive lymphoproliferative disorders and lupus-like autoimmune diseases. Previous studies have shown that short-term administrations of agonistic monoclonal antibodies against CD137, another TNF-receptor family member, activate T cells and induce rejection of allografts and established tumors. Here we report that treatment with an agonistic monoclonal antibody to CD137 (2A) blocks lymphadenopathy and spontaneous autoimmune diseases in Fas-deficient MRL/lpr mice, ultimately leading to their prolonged survival. Notably, 2A treatment rapidly augments IFN-gamma production, and induces the depletion of autoreactive B cells and abnormal double-negative T cells, possibly by increasing their apoptosis through Fas- and TNF receptor-independent mechanisms. This study demonstrates that agonistic monoclonal antibodies specific for costimulatory molecules can be used as novel therapeutic agents to delete autoreactive lymphocytes and block autoimmune disease progression. 相似文献
8.
P. K. Subudhi S. Nandi C. Casal S. S. Virmani N. Huang 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,96(6-7):941-949
The cytoplasmic genetic male-sterile (CMS) lines developed at the International Rice Research Institute are valuable in producing
tropical rice hybrids. Efficient use of CMS lines in hybrid rice production will depend on their level of genetic diversity.
Aside from morphological characterization, molecular analysis based on DNA markers can provide information on the genetic
diversity of the germplasm. The Amplified Fragment Length Polymorphism (AFLP) technique was used to fingerprint 71 CMS lines
and four rice cultivars, ‘IR64’, ‘Azucena’, ‘IR74’, and ‘FR13A’. Eleven primer pair combinations specific to the enzymes PstI and MseI were used to generate 530 AFLP markers, 176 of which were polymorphic. Each CMS line revealed a distinct fingerprint. The
AFLP marker-based dendrogram depicted genetic variation among the CMS lines. The CMS lines developed in japonica background
grouped with ‘Azucena’, a japonica cultivar. None of the CMS lines clustered with ‘FR13A’, a flood-tolerant traditional indica
variety. ‘IR64’ was found to be distinct from the other indica CMS lines and clustered with lines developed in its background.
The grouping of CMS lines into a few groups is useful for breeders in selecting genetically diverse CMS lines for hybrid rice
production and in avoiding test crossing every CMS line empirically. This study demonstrated that AFLP is a powerful and reliable
tool in determining the genetic relationships and in producing distinct fingerprints of rice cultivars.
Received: 20 December 1996 / Accepted: 9 October 1997 相似文献
9.
Prasanta K. Subudhi Teresa De Leon Pradeep K. Singh Arnold Parco Marc A. Cohn Takuji Sasaki 《PloS one》2015,10(6)
Chromosome segment substitution lines (CSSLs) are a powerful alternative for locating quantitative trait loci (QTL), analyzing gene interactions, and providing starting materials for map-based cloning projects. We report the development and characterization of a CSSL library of a U.S. weedy rice accession ‘PSRR-1’ with genome-wide coverage in an adapted rice cultivar ‘Bengal’ background. The majority of the CSSLs carried a single defined weedy rice segment with an average introgression segment of 2.8 % of the donor genome. QTL mapping results for several agronomic and domestication traits from the CSSL population were compared with those obtained from two recombinant inbred line (RIL) populations involving the same weedy rice accession. There was congruence of major effect QTLs between both types of populations, but new and additional QTLs were detected in the CSSL population. Although, three major effect QTLs for plant height were detected on chromosomes 1, 4, and 8 in the CSSL population, the latter two escaped detection in both RIL populations. Since this was observed for many traits, epistasis may play a major role for the phenotypic variation observed in weedy rice. High levels of shattering and seed dormancy in weedy rice might result from an accumulation of many small effect QTLs. Several CSSLs with desirable agronomic traits (e.g. longer panicles, longer grains, and higher seed weight) identified in this study could be useful for rice breeding. Since weedy rice is a reservoir of genes for many weedy and agronomic attributes, the CSSL library will serve as a valuable resource to discover latent genetic diversity for improving crop productivity and understanding the plant domestication process through cloning and characterization of the underlying genes. 相似文献
10.
Kurdrid P Subudhi S Cheevadhanarak S Tanticharoen M Hongsthong A 《Molecular biology reports》2007,34(4):261-266
When the gene desD encoding Spirulina Δ6-desaturase was heterologously expressed in E. coli, the enzyme was expressed without the ability to function. However, when this enzyme was co-expressed with an immediate electron
donor, i.e. the cytochrome b
5 domain from Mucor rouxii, the results showed the production of GLA (γ-linolenic acid), the product of the reaction catalyzed by Δ6-desaturase. The results revealed that in E. coli cells, where cytochrome b
5 is absent and ferredoxin, a natural electron donor of Δ6-desaturase, is present at a very low level, the cytochrome b
5 domain can complement for the function of ferredoxin in the host cells. In the present study, the Spirulina-ferredoxin gene was cloned and co-expressed with the Δ6-desaturase in E. coli. In comparison to the co-expression of cytochrome b
5
with the Δ6-desaturase, the co-expression with ferredoxin did not cause any differences in the GLA level. Moreover, the cultures containing
the Δ6-desaturase co-expressed with cytochrome b
5 and ferredoxin were exogenously supplied with the intermediate electron donors, NADPH (nicotinamide adenine dinucleotide
phosphate, reduced form) and FADH2 (flavin adenine dinucleotide, reduced form), respectively. The GLA level in these host cells increased drastically, by approximately
50%, compared to the cells without the intermediate electron donors. The data indicated that besides the level of immediate
electron donors, the level of intermediate electron donors is also critical for GLA production. Therefore, if the pools of
the immediate and intermediate electron donors in the cells are manipulated, the GLA production in the heterologous host will
be affected. 相似文献