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121.
Studies have suggested that the expression, translocation, and function of alpha4beta2 nicotinic receptors may be modulated by alpha4 subunit phosphorylation, but little direct evidence exists to support this idea. The objective of these experiments was to identify specific serine/threonine residues on alpha4 subunits that are phosphorylated in vivo by cAMP-dependent protein kinase and protein kinase C (PKC). To accomplish this, DNAs coding for human alpha4 subunits containing alanines in place of serines/threonines predicted to represent phosphorylation sites were constructed, and transiently transfected with the DNA coding for wild-type beta2 subunits into SH-EP1 cells. Cells were pre-incubated with (32)Pi and incubated in the absence or presence of forskolin or phorbol 12,13-dibutyrate. Immunoprecipitated alpha4 subunits were subjected to immunoblot, autoradiographic and phosphoamino acid analyses, and two-dimensional phosphopeptide mapping. Results confirmed the presence of two alpha4 protein bands, a major band of 71/75 kDa and a minor band of 80/85 kDa. Phosphoamino acid analysis of the major band indicated that only serine residues were phosphorylated. Phosphopeptide maps demonstrated that Ser362 and 467 on the M3/M4 cytoplasmic domain of the alpha4 subunit represent major cAMP-dependent protein kinase phosphorylation sites, while Ser550 also contained within this major intracellular loop is a major site for protein kinase C phosphorylation. 相似文献
122.
Bovine viral diarrhea virus: prevention of persistent fetal infection by a combination of two mutations affecting Erns RNase and Npro protease 下载免费PDF全文
Meyers G Ege A Fetzer C von Freyburg M Elbers K Carr V Prentice H Charleston B Schürmann EM 《Journal of virology》2007,81(7):3327-3338
Different genetically engineered mutants of bovine viral diarrhea virus (BVDV) were analyzed for the ability to establish infection in the fetuses of pregnant heifers. The virus mutants exhibited either a deletion of the overwhelming part of the genomic region coding for the N-terminal protease N(pro), a deletion of codon 349, which abrogates the RNase activity of the structural glycoprotein E(rns), or a combination of both mutations. Two months after infection of pregnant cattle with wild-type virus or either of the single mutants, the majority of the fetuses contained virus or were aborted or found dead in the uterus. In contrast, the double mutant was not recovered from fetal tissues after a similar challenge, and no dead fetuses were found. This result was verified with a nonrelated BVDV containing similar mutations. After intrauterine challenge with wild-type virus, mutated viruses, and cytopathogenic BVDV, all viruses could be detected in fetal tissue after 5, 7, and 14 days. Type 1 interferon (IFN) could be detected in fetal serum after challenge, except with wild-type noncytopathogenic BVDV. On days 7 and 14 after challenge, the largest quantities of IFN in fetal serum were induced by the N(pro) and RNase-negative double mutant virus. The longer duration of fetal infection with the double mutant resulted in abortion. Therefore, for the first time, we have demonstrated the essential role of both N(pro) and E(rns) RNase in blocking interferon induction and establishing persistent infection by a pestivirus in the natural host. 相似文献
123.
Identification of major sporulation proteins of Myxococcus xanthus using a proteomic approach 下载免费PDF全文
Dahl JL Tengra FK Dutton D Yan J Andacht TM Coyne L Windell V Garza AG 《Journal of bacteriology》2007,189(8):3187-3197
Myxococcus xanthus is a soil-dwelling, gram-negative bacterium that during nutrient deprivation is capable of undergoing morphogenesis from a vegetative rod to a spherical, stress-resistant spore inside a domed-shaped, multicellular fruiting body. To identify proteins required for building stress-resistant M. xanthus spores, we compared the proteome of liquid-grown vegetative cells with the proteome of mature fruiting body spores. Two proteins, protein S and protein S1, were differentially expressed in spores, as has been reported previously. In addition, we identified three previously uncharacterized proteins that are differentially expressed in spores and that exhibit no homology to known proteins. The genes encoding these three novel major spore proteins (mspA, mspB, and mspC) were inactivated by insertion mutagenesis, and the development of the resulting mutant strains was characterized. All three mutants were capable of aggregating, but for two of the strains the resulting fruiting bodies remained flattened mounds of cells. The most pronounced structural defect of spores produced by all three mutants was an altered cortex layer. We found that mspA and mspB mutant spores were more sensitive specifically to heat and sodium dodecyl sulfate than wild-type spores, while mspC mutant spores were more sensitive to all stress treatments examined. Hence, the products of mspA, mspB, and mspC play significant roles in morphogenesis of M. xanthus spores and in the ability of spores to survive environmental stress. 相似文献
124.
PTX3 interacts with inter-alpha-trypsin inhibitor: implications for hyaluronan organization and cumulus oophorus expansion 总被引:1,自引:0,他引:1
Scarchilli L Camaioni A Bottazzi B Negri V Doni A Deban L Bastone A Salvatori G Mantovani A Siracusa G Salustri A 《The Journal of biological chemistry》2007,282(41):30161-30170
Pentraxin 3 (PTX3) and heavy chains (HCs) of inter-alpha-trypsin inhibitor (IalphaI) are essential for hyaluronan (HA) organization within the extracellular matrix of the cumulus oophorus, which is critical for in vivo oocyte fertilization and female fertility. In this study, we examined the possibility that these molecules interact and cooperate in this function. We show that HCs and PTX3 colocalize in the cumulus matrix and coimmunoprecipitate from cumulus matrix extracts. Coimmunoprecipitation experiments and solid-phase binding assays performed with purified human IalphaI and recombinant PTX3 demonstrate that their interaction is direct and not mediated by other matrix components. PTX3 does not bind to IalphaI subcomponent bikunin and, accordingly, bikunin does not compete for the binding of PTX3 to IalphaI, indicating that PTX3 interacts with IalphaI subcomponent HC only. Recombinant PTX3-specific N-terminal region, but not the PTX3-pentraxin C-terminal domain, showed the same ability as full-length protein to bind to HCs and to enable HA organization and matrix formation by Ptx3(-/-) cumulus cell oocyte complexes cultured in vitro. Furthermore, a monoclonal antibody raised against PTX3 N terminus, which inhibits PTX3/IalphaI interaction, also prevents recombinant full-length PTX3 from restoring a normal phenotype to in vitro-cultured Ptx3(-/-) cumuli. These results indicate that PTX3 directly interacts with HCs of IalphaI and that such interaction is essential for organizing HA in the viscoelastic matrix of cumulus oophorus, highlighting a direct functional link between the two molecules. 相似文献
125.
Admixture in Mexico City: implications for admixture mapping of Type 2 diabetes genetic risk factors
Martinez-Marignac VL Valladares A Cameron E Chan A Perera A Globus-Goldberg R Wacher N Kumate J McKeigue P O'Donnell D Shriver MD Cruz M Parra EJ 《Human genetics》2007,120(6):807-819
Admixture mapping is a recently developed method for identifying genetic risk factors involved in complex traits or diseases
showing prevalence differences between major continental groups. Type 2 diabetes (T2D) is at least twice as prevalent in Native
American populations as in populations of European ancestry, so admixture mapping is well suited to study the genetic basis
of this complex disease. We have characterized the admixture proportions in a sample of 286 unrelated T2D patients and 275
controls from Mexico City and we discuss the implications of the results for admixture mapping studies. Admixture proportions
were estimated using 69 autosomal ancestry-informative markers (AIMs). Maternal and paternal contributions were estimated
from geographically informative mtDNA and Y-specific polymorphisms. The average proportions of Native American, European and,
West African admixture were estimated as 65, 30, and 5%, respectively. The contributions of Native American ancestors to maternal
and paternal lineages were estimated as 90 and 40%, respectively. In a logistic model with higher educational status as dependent
variable, the odds ratio for higher educational status associated with an increase from 0 to 1 in European admixture proportions
was 9.4 (95%, credible interval 3.8–22.6). This association of socioeconomic status with individual admixture proportion shows
that genetic stratification in this population is paralleled, and possibly maintained, by socioeconomic stratification. The
effective number of generations back to unadmixed ancestors was 6.7 (95% CI 5.7–8.0), from which we can estimate that genome-wide
admixture mapping will require typing about 1,400 evenly distributed AIMs to localize genes underlying disease risk between
populations of European and Native American ancestry. Sample sizes of about 2,000 cases will be required to detect any locus
that contributes an ancestry risk ratio of at least 1.5. 相似文献
126.
Luis A. Materon Martha Martinez-Garcia Veronica McDonald 《World journal of microbiology & biotechnology》2007,23(9):1281-1287
Foodborne illness outbreaks involving cantaloupes have increased dramatically in the past 15 years in the United States and
other countries. The need for the identification of the microbial sources that contaminate cantaloupe rinds has been raised
by various investigators. This study was undertaken to identify the agricultural, industrial and human sources of microbial
contamination from the pre- to post-harvest operations of cantaloupes grown at ten different farms in southern Texas. Results
indicate that irrigation water contained a wide range of microorganisms that could cause human illness and were able to survive
on the rind of cantaloupes before, at, and after harvesting. Fungi, total aerobic bacteria and total coliform bacteria were
not completely eliminated by chlorinated water in the disinfection tanks of the six packinghouses under investigation. There
were significant (P < 0.05) reductions on rind populations of fungi and total aerobic bacteria as well as drastic reductions in total coliform
bacteria on the rinds after the disinfection and rinsing steps in all packing facilities. There was no evidence of the presence
of Escherichia coli O157:H7 on packed cantaloupes across packinghouses. Less than a geometric mean of 1 c.f.u. cm−2 of salmonellae were detected on the surface of packed cantaloupes in two of the packinghouses, and approximately ten times
more salmonellae were found on the packed fruit processed in the remaining packinghouses. A similar trend was observed with
listeriae. Results suggested that microbial loads originating from river water may survive on the rind or may re-infest cantaloupes
after the disinfection and rinsing process at the packinghouses. Disinfection techniques and aseptic handling of cantaloupes
at the packing facilities need a closer evaluation to ensure a safe product. 相似文献
127.
Manera C Cascio MG Benetti V Allarà M Tuccinardi T Martinelli A Saccomanni G Vivoli E Ghelardini C Di Marzo V Ferrarini PL 《Bioorganic & medicinal chemistry letters》2007,17(23):6505-6510
A series of new 1,8-naphthyridine and quinoline derivatives were synthesized and evaluated for their cannabinoid receptor affinity. In particular, compounds 2, 5, 11, and 13 showed a high CB(2) affinity and CB(2) versus CB(1) selectivity, in agreement with molecular modeling studies. Furthermore, compound 2 also exhibited in vivo antinociceptive effects. 相似文献
128.
UmuD and RecA directly modulate the mutagenic potential of the Y family DNA polymerase DinB 总被引:3,自引:0,他引:3
DinB is the only translesion Y family DNA polymerase conserved among bacteria, archaea, and eukaryotes. DinB and its orthologs possess a specialized lesion bypass function but also display potentially deleterious -1 frameshift mutagenic phenotypes when overproduced. We show that the DNA damage-inducible proteins UmuD(2) and RecA act in concert to modulate this mutagenic activity. Structural modeling suggests that the relatively open active site of DinB is enclosed by interaction with these proteins, thereby preventing the template bulging responsible for -1 frameshift mutagenesis. Intriguingly, residues that define the UmuD(2)-interacting surface on DinB statistically covary throughout evolution, suggesting a driving force for the maintenance of a regulatory protein-protein interaction at this site. Together, these observations indicate that proteins like RecA and UmuD(2) may be responsible for managing the mutagenic potential of DinB orthologs throughout evolution. 相似文献
129.
Hartl D Latzin P Hordijk P Marcos V Rudolph C Woischnik M Krauss-Etschmann S Koller B Reinhardt D Roscher AA Roos D Griese M 《Nature medicine》2007,13(12):1423-1430
Interleukin-8 (IL-8) activates neutrophils via the chemokine receptors CXCR1 and CXCR2. However, the airways of individuals with cystic fibrosis are frequently colonized by bacterial pathogens, despite the presence of large numbers of neutrophils and IL-8. Here we show that IL-8 promotes bacterial killing by neutrophils through CXCR1 but not CXCR2. Unopposed proteolytic activity in the airways of individuals with cystic fibrosis cleaved CXCR1 on neutrophils and disabled their bacterial-killing capacity. These effects were protease concentration-dependent and also occurred to a lesser extent in individuals with chronic obstructive pulmonary disease. Receptor cleavage induced the release of glycosylated CXCR1 fragments that were capable of stimulating IL-8 production in bronchial epithelial cells via Toll-like receptor 2. In vivo inhibition of proteases by inhalation of alpha1-antitrypsin restored CXCR1 expression and improved bacterial killing in individuals with cystic fibrosis. The cleavage of CXCR1, the functional consequences of its cleavage, and the identification of soluble CXCR1 fragments that behave as bioactive components represent a new pathophysiologic mechanism in cystic fibrosis and other chronic lung diseases. 相似文献