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941.
Ai X Semesi A Yee A Arrowsmith CH Choy WY Li SS 《Protein science : a publication of the Protein Society》2008,17(1):154-158
Atu4866 is a 79-residue conserved hypothetical protein of unknown function from Agrobacterium tumefaciens. Protein sequence alignments show that it shares > or =60% sequence identity with 20 other hypothetical proteins of bacterial origin. However, the structures and functions of these proteins remain unknown so far. To gain insight into the function of this family of proteins, we have determined the structure of Atu4866 as a target of a structural genomics project using solution NMR spectroscopy. Our results reveal that Atu4866 adopts a streptavidin-like fold featuring a beta-barrel/sandwich formed by eight antiparallel beta-strands. Further structural analysis identified a continuous patch of conserved residues on the surface of Atu4866 that may constitute a potential ligand-binding site. 相似文献
942.
Over-expression of an arabidopsis family A sucrose phosphate synthase (SPS) gene alters plant growth and fibre development 总被引:1,自引:0,他引:1
The objective of this study was to manipulate the intracellular pools of sucrose by differentially expressing exogenous sucrose
phosphate synthase (SPS) and investigating its role in regulating plant growth and fibre development. Tobacco (Nicotiana tabacum cv. Xanthi) plants were transformed with an arabidopsis SPS gene under the regulation of the ubiquitously expressed tandem
repeat of the 35S cauliflower mosaic virus promoter, and subject to growth trials and fibre characterization. It was apparent
that over-expression of SPS resulted in substantially elevated concentrations of sink sucrose pools compared to wild-type
plants, while source tissue sucrose pools remained the same. All transformed plants had significantly increased stem height,
which was ascribed to internode elongation, and greater stem diameters, longer fibers and increased total dry biomass relative
to the control plants. Difference in the chemical composition of either the storage or structural carbohydrates of the wild-type
and SPS transgenic lines were only minor. The correlation between increased stem sucrose content and plant phenotypes with
elevated SPS gene expression confirm a role for sucrose availability in controlling plant growth and fibre elongation. 相似文献
943.
944.
An amplified fragment length polymorphism (AFLP) linkage map for coastal Douglas-fir (Pseudotsuga menziesii) was constructed from eight full-sib families each consisting of 40 progeny. These families were part of the British Columbia
Ministry of Forests second-generation progeny test program and represent typical family sizes used in progeny trials. For
map construction, ten primer pairs using EcoRI+3 and MseI+4 were employed to identify and assay AFLP loci that segregated in backcross configurations. A new technique was used to
obtain a single recombination rate for each pair of marker loci: for each locus pair, a recombination rate and log-odd value
were estimated across all segregating families using a joint maximum likelihood function that considered the full dataset
of segregating genotypes. The resulting matrix of recombination rates between all pairs of loci was used to construct an integrated
linkage map using JoinMap. The final map consisted of 19 linkage groups spanning 938.6 cM at an average distance of 9.3 cM
between markers. The simultaneous integration of data from multiple families may provide an effective way to construct a linkage
map, using the genetic resources inherent in most tree improvement programs, where progeny tests of small size are conducted.
The statistical property of number of families used is briefly discussed. For our data, at least three to four families greatly
increased the chance of obtaining an informative locus in at least one family. Families as small as ten are adequate for closely
linked loci (<10 cM), while the size used in our study (40) is adequate for loci within 30 cM. 相似文献
945.
Bearson BL Bearson SM Uthe JJ Dowd SE Houghton JO Lee I Toscano MJ Lay DC 《Microbes and infection / Institut Pasteur》2008,10(7):807-816
Catecholamines may stimulate enteric bacteria including the foodborne pathogen Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) by two mechanisms in vivo: as a quorum sensing signal and a supplier of iron. To identify genes of Salmonella Typhimurium that respond to norepinephrine, transposon mutagenesis and DNA microarray analysis were performed. Insertional mutations in the following genes decreased norepinephrine-enhanced growth: degS, entE, entF, fes, gpmA, hfq, STM3846. DNA microarray and real-time RT-PCR analyses revealed a decrease in the expression of several genes involved in iron acquisition and utilization during norepinephrine exposure, signifying the iron-limiting conditions of serum-SAPI minimal medium and the siderophore-like activity of norepinephrine. Unlike the wild-type parent strain, growth of neither a fepA iroN cirA mutant nor a fepC mutant, harboring deletional mutations in the outer and inner membrane transporters of enterochelin, respectively, was enhanced by norepinephrine. However, growth of the fepC and the fepA iroN cirA mutants could be rescued by an alternative siderophore, ferrioxamine E, further validating the role of norepinephrine in supplying the organism with iron via the catecholate-specific iron transport system. Contrary to previous reports using small animal models, the fepA iroN cirA mutant of Salmonella Typhimurium colonized the swine gastrointestinal tract, as did the fepC mutant. 相似文献
946.
947.
Shawn A Hawkins Alice C Layton Steven Ripp Dan Williams Gary S Sayler 《Virology journal》2008,5(1):1-5
Background
Co-circulation of multiple dengue virus serotypes has been reported from many parts of the world including India, however concurrent infection with more than one serotype of dengue viruses in the same individual is rarely documented. An outbreak of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) occurred in and around Delhi in 2006. This is the first report from India with high percentage of concurrent infections with different dengue virus serotypes circulating during one outbreak.Results
Acute phase sera from patients were tested for the presence of dengue virus RNA by RT-PCR assay. Of the 69 samples tested for dengue virus RNA, 48 (69.5%) were found to be positive. All the four dengue virus serotypes were found to be co-circulating in this outbreak with DENV-3 being the predominant serotype. In addition in 9 of 48 (19%) dengue virus positive samples, concurrent infection with more than one dengue virus serotype were identified.Conclusion
This is the first report in which concurrent infections with different dengue virus serotypes is being reported during an outbreak from India. Delhi is now truly hyperendemic for dengue. 相似文献948.
Background
Conserved Wnt ligands are critical for signalling during development; however, various factors modulate their activity. Among these factors are the Secreted Frizzled-Related Proteins (SFRP). We previously isolated the SFRP-4 gene from an involuting rat mammary gland and later showed that transgenic mice inappropriately expressing SFRP-4 during lactation exhibited a high level of apoptosis with reduced survival of progeny.Results
In order to address the questions related to the mechanism of Wnt signalling and its inhibition by SFRP-4 which we report here, we employed partially-purified Wnt-3a in a co-culture model system. Ectopic expression of SFRP-4 was accomplished by infection with a pBabepuro construct. The co-cultures comprised Line 31E mouse mammary secretory epithelial cells and Line 30F, undifferentiated, fibroblast-like mouse mammary cells. In vitro differentiation of such co-cultures can be demonstrated by induction of the β-casein gene in response to lactogenic hormones. We show here that treatment of cells with partially-purified Wnt-3a initiates Dvl-3, Akt/PKB and GSK-3β hyperphosphorylation and β-catenin activation. Furthermore, while up-regulating the cyclin D1 and connexin-43 genes and elevating transepithelial resistance of Line 31E cell monolayers, Wnt-3a treatment abrogates differentiation of co-cultures in response to the lactogenic hormones prolactin, insulin and glucocorticoid. Cells which express SFRP-4, however, are largely unaffected by Wnt-3a stimulation. Since a physical association between Wnt-3a and SFRP-4 could be demonstrated with immunoprecipitation/Western blotting experiments, this interaction, presumably owing to the Frizzled homology region typical of all SFRPs, explains the refractory response to Wnt-3a which was observed.Conclusion
This study demonstrates that Wnt-3a treatment activates the Wnt signalling pathway and interferes with in vitro differentiation of mammary co-cultures to β-casein production in response to lactogenic hormones. Similarly, in another measure of differentiation, following Wnt-3a treatment mammary epithelial cells could be shown to up-regulate the cyclin D1 and connexin-43 genes while phenotypically they show increased transepithelial resistance across the cell monolayer. All these behavioural changes can be blocked in mammary epithelial cells expressing SFRP-4. Thus, our data illustrate in an in vitro model a mechanism by which SFRP-4 can modulate a differentiation response to Wnt-3a. 相似文献949.
Hunt SC Stone S Xin Y Scherer CA Magness CL Iadonato SP Hopkins PN Adams TD 《Obesity (Silver Spring, Md.)》2008,16(4):902-904
Variants in the FTO gene have been strongly associated with obesity in a very large sample (38,759) of diabetic and control subjects. To replicate these findings, the previously reported SNP in the FTO gene (rs9939609, T/A) was genotyped in 5,607 subjects from five different Utah studies. The studies included a random sample of the Utah population, families selected for aggregation of extreme thinness, families selected for severe obesity, a series of unrelated severe obesity subjects, and families participating in a 25-year longitudinal study of cardiovascular disease and aging. Results show a strong significant increase in the rs9939609 A allele frequency with increasing BMI (P < 0.0001). In the longitudinal study, FTO genotypes were significantly associated with BMI at a baseline exam, a 2(1/2)-year follow-up exam and a 25-year follow-up exam using an additive genetic model. The mean genotype difference in BMI ranged from 1.3 to 2.1 kg/m(2) across exams. The genotype difference in BMI means was established in youth, and at-risk subjects under age 20 at baseline had a significantly larger 25-year BMI increase (10.0 for A/A; 9.7 for A/T, and 8.5 kg/m(2) for T/T, P = 0.05). We conclude that the BMI increases associated with FTO genotypes begin in youth and are maintained throughout adulthood. 相似文献
950.