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101.
Nancy C. Tuchman Kirk A. Wahtera Robert G. Wetzel Nicole M. Russo Grace M. Kilbane Lisa M. Sasso James A. Teeri 《Freshwater Biology》2003,48(8):1432-1439
1. Populus tremuloides leaf litter was produced under elevated (ELEV = 720 ppm) and ambient (AMB = 360 ppm) atmospheric CO2 conditions. Leaf chemical quality was significantly altered by CO2 enrichment. ELEV leaves had significantly higher concentrations of phenolic compounds and lignins, and higher C : N ratios than AMB. 2. Leaf litter was incubated in a headwater stream for 14 days to become colonised by microorganisms; aquatic bacterial productivity was significantly lower on ELEV than on AMB leaf litter. Colonised leaves were fed to four species of detritivorous mosquito larvae to assess their survivorship and development rates. 3. Larval mortality was 2.2 times higher for Aedes albopictus fed ELEV litter when compared with AMB. Although mortality of A. triseriatus, A. aegypti and Armigeres subalbatus was not affected by treatment, larval development rate was delayed by 78, 25 and 27%, respectively, when fed ELEV litter. 4. Increased mosquito mortality and/or delayed larval development rates are more likely to have negative implications for food web structure and productivity in ecosystems where immature stages of mosquitoes are an important food source of predators. 相似文献
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The particle gun approach was used for the quantification of promoter efficiency in a test system for transient gene expression.
β-Glucuronidase was used as reporter gene for determining promotote strength. The variability inherent in this gene transfer
system was considerably reduced by calculating a transformation efficiency factor given by the expression of a cotransferred
second reporter gene (firefly luciferase). The calibration of β-glucuronidase activity by the transformation efficiency factor
caused a lower statistical variance of the values and allowed reliable results to be obtained with a smaller set of repetitions.
The CaMV 35S promoter (as a control) and the monocot-specific promoters for maize polyubiquitin1, rice actin 1 and the maize-derivedEmu were characterized and compared with respect to expression strength, as tested under identical conditions in suspension cell
cultures of maize, barley and tobacco. Compared to the 35S promoter, the monocot-specific promoters show up to 15-fold higher
expression in maize and barley but give only weak expression in tobacco. No expression was found for the rice actin 1 promoter
in tobacco. The level of reporter gene expression is influenced by the osmotic potential in the agar medium. For theEmu promoter, the calibrated β-glucuronidase activities remained mearly constant at low sucrose concentrations. Above 8% sucrose,
the calibrated activities increased steadily with increasing osmotic conditions, reaching a three-to four-fold higher level
at the highest sucrose concentration (32%) as compared to the standard concentration (4% sucrose) in the medium. 相似文献
105.
106.
M Tuchman M T McCann M M Thompson M Y Tsai R Giguere B Lemieux 《Biochemical medicine and metabolic biology》1992,48(1):64-68
Urinary methylmalonic acid (MMA) and 4-hydroxyphenyllactic acid (HPL) have been determined in 3345 and 2498 3-week-old newborns, respectively. Urine was collected onto filter paper and assayed by a rapid gas chromatography-mass spectrometry method. Forty-six infants (1.7%) had elevated MMA levels (greater than 58.5 micrograms/mg creatinine, means + 5 SD) and 31 infants (1.2%) had elevated levels of HPL (greater than 87.7 micrograms/mg creatinine, means + 5 SD). Fifteen infants with elevated values of MMA were retested from one to several months after the first test. In 12 infants the MMA levels normalized, while in the remaining three, elevated methylmalonic acid persisted. Nine infants with elevated values of HPL were retested, and in all except one, HPL levels normalized. No access to clinical evaluation of the infants was available. Transient methylmalonic aciduria and transient tyrosyluria affect a substantial number of infants and the clinical significance of this phenomenon has yet to be determined. 相似文献
107.
de Rosbo NK Kaye JF Eisenstein M Mendel I Hoeftberger R Lassmann H Milo R Ben-Nun A 《Journal of immunology (Baltimore, Md. : 1950)》2004,173(2):1426-1435
Autoimmune response to the myelin-associated oligodendrocytic basic protein (MOBP), a CNS-specific myelin constituent, was recently suggested to play a role in the pathogenesis of multiple sclerosis (MS). The pathogenic autoimmune response to MOBP and the associated pathology in the CNS have not yet been fully investigated. In this study, we have characterized the clinical manifestations, pathology, T cell epitope-specificity, and TCRs associated with experimental autoimmune encephalomyelitis (EAE) induced in SJL/J mice with recombinant mouse MOBP (long isoform, 170 aa). Analysis of encephalitogenic MOBP-reactive T cells for reactivity to overlapping MOBP peptides defined MOBP15-36 as their major immunodominant epitope. Accordingly, MOBP15-36 was demonstrated to be the major encephalitogenic MOBP epitope for SJL/J mice, inducing severe/chronic clinical EAE associated with intense perivascular and parenchymal infiltrations, widespread demyelination, axonal loss, and remarkable optic neuritis. Molecular modeling of the interaction of I-A(s) with MOBP15-36, together with analysis of the MOBP15-36-specific T cell response to truncated peptides, suggests MOBP20-28 as the core sequence for I-A(s)-restricted recognition of the encephalitogenic region MOBP15-36. Although highly focused in their epitope specificity, the encephalitogenic MOBP-reactive T cells displayed a widespread usage of TCR Vbeta genes. These results would therefore favor epitope-directed, rather than TCR-targeted, approaches to therapy of MOBP-associated pathogenic autoimmunity. Localization by molecular modeling of a potential HLA-DRB1*1501-associated MOBP epitope within the encephalitogenic MOBP15-36 sequence suggests the potential relevance of T cell reactivity against MOBP15-36 to MS. The reactivity to MOBP15-36 detected in MS shown here and in another study further emphasizes the potential significance of this epitope for MS. 相似文献
108.
Shi D Morizono H Yu X Roth L Caldovic L Allewell NM Malamy MH Tuchman M 《The Journal of biological chemistry》2005,280(15):14366-14369
We have identified in Xanthomonas campestris a novel N-acetylornithine transcarbamylase that replaces ornithine transcarbamylase in the canonic arginine biosynthetic pathway of several Eubacteria. The crystal structures of the protein in the presence and absence of the reaction product, N-acetylcitrulline, were determined. This new family of transcarbamylases lacks the DxxSMG motif that is characteristic of all ornithine transcarbamylases (OTCases) and contains a novel proline-rich loop that forms part of the active site. The specificity for N-acetylornithine is conferred by hydrogen bonding with residues in the proline-rich loop via water molecules and by hydrophobic interactions with residues from the adjacent 80's, 120's, and proline-rich loops. This novel protein structure provides a starting point for rational design of specific analogs that may be useful in combating human and plant pathogens that utilize acetylornithine transcarbamylase rather than ornithine transcarbamylase. 相似文献
109.
Engler TA Malhotra S Burkholder TP Henry JR Mendel D Porter WJ Furness K Diefenbacher C Marquart A Reel JK Li Y Clayton J Cunningham B McLean J O'toole JC Brozinick J Hawkins E Misener E Briere D Brier RA Wagner JR Campbell RM Anderson BD Vaughn R Bennett DB Meier TI Cook JA 《Bioorganic & medicinal chemistry letters》2005,15(4):899-903
Many 3-aryl-4-(1,2,3,4-tetrahydro[1,4]diazepino[6,7,1-hi]indol-7-yl)maleimides exhibit potent GSK3 inhibitory activity (<100 nM IC(50)), although few show significant selectivity (>100x) versus CDK2, CDK4, or PKCbetaII. However, combining 3-(imidazo[1,2-a]pyridin-3-yl), 3-(pyrazolo[1,5-a]pyridin-3-yl) or aza-analogs with a 4-(2-acyl-(1,2,3,4-tetrahydro[1,4]diazepino[6,7,1-hi]indol-7-yl)) group on the maleimide resulted in very potent inhibitors of GSK3 (=5 nM) with >160 to >10,000-fold selectivity versus CDK2/4 and PKCbetaII. These compounds also inhibited tau phosphorylation in cells and were effective in lowering plasma glucose in a rat model of type 2 diabetes (ZDF rat). 相似文献
110.
Vectors for RNAi technology in poplar 总被引:7,自引:0,他引:7
Meyer S Nowak K Sharma VK Schulze J Mendel RR Hänsch R 《Plant biology (Stuttgart, Germany)》2004,6(1):100-104
Abstract: The potential of double-stranded RNA interference (RNAi) technology was studied for down-regulation of gene expression in poplar. A set of vectors was constructed generating RNAs capable of duplex formation of sequences specific for the β-glucuronidase (GUS) reporter gene system. These gene cassettes are driven by the CaMV-35S promoter. To address the question of gene silencing, we tested the functionality of these vectors, both in transient assays by transforming protoplasts with the RNAi constructs, and in stably transformed GUSexpressing poplar plants. Agrobacterium -mediated transformation of those GUS-expressing plants with a GUS-specific RNAi construct showed a strong down-regulation of the reporter gene. From these results we conclude that RNAi is also functional in poplar. 相似文献