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81.
Ringel AK Wilkens E Hortig D Willke T Vorlop KD 《Applied microbiology and biotechnology》2012,93(3):1049-1056
A new screening method was developed and established to find high-performance bacteria for the conversion of crude glycerol
to 1,3-propanediol. Three soil samples from palm oil-rich habitats were investigated using crude glycerol of a German biodiesel
plant. Nine promising 1,3-propanediol producers could be found. Because of a special pH buffer system, a fast evaluation on
microscale and high 1,3-propanediol concentrations up to 40 g L−1 could be achieved. Three strains demonstrated very high product tolerance and were identified as Clostridium butyricum. Two strains, AKR91b and AKR102a, grew and produced 1,3-propanediol in the presence of 60 g L−1 initial 1,3-propanediol, the strain AKR92a even in the presence of 77 g L−1 1,3-propanediol. The strains AKR91b and AKR102a tolerated up to 150 g L−1 crude glycerol and produced 80% of the 1,3-propanediol attained from pure glycerol of the same concentration. Further criteria
for the choice of a production strain were the pathogenicity (risk class), ability to grow on low-cost media, e.g., with less
yeast extract, and robustness, e.g., process stability after several bioconversions. Overall, the strain C. butyricum AKR102a was chosen for further process optimization and scale-up due to its high productivity and high final concentration
in a pH-regulated bioreactor. 相似文献
82.
Phospholipids are asymmetrically distributed across the membrane of all cells, including red blood cells (RBCs). Phosphatidylserine (PS) is mainly localized in the cytoplasmic membrane leaflet, but during RBC ageing it flip-flops to the external leaflet—a process that is increased in certain pathological conditions (e.g., β-thalassemia). PS externalization in RBCs mediates their phagocytosis by macrophages and removal from the circulation. PS is usually measured by flow cytometry and is reported as the percentage of cells with external PS. In the current study, we developed a novel two-step flow cytometry procedure to quantitatively measure not only the external PS but also the intracellular and shed PS. In this method, PS is first bound to fluorescent annexin V, and then the residual nonbound annexin is quantified by binding to PS exposed on apoptotic cells. Using this method, we measured 1.1 ± 0.2 and 0.12 ± 0.04 μmol inner and external PS, respectively, per 107 normal RBCs. Thalassemic RBCs demonstrated increased PS externalization (1.7-fold) and shedding (11-fold) that was accompanied by lower intracellular PS (31%). These results suggest that quantitative flow cytometry of PS could have a diagnostic value in evaluating the pathology of RBCs in hemolytic anemias associated with increased PS externalization and shortening of the RBC life span. 相似文献
83.
84.
Ayelet Zauberman Avital Tidhar Yinon Levy Erez Bar-Haim Gideon Halperin Yehuda Flashner Sara Cohen Avigdor Shafferman Emanuelle Mamroud 《PloS one》2009,4(6)
An important virulence strategy evolved by bacterial pathogens to overcome host defenses is the modulation of host cell death. Previous observations have indicated that Yersinia pestis, the causative agent of plague disease, exhibits restricted capacity to induce cell death in macrophages due to ineffective translocation of the type III secretion effector YopJ, as opposed to the readily translocated YopP, the YopJ homologue of the enteropathogen Yersinia enterocolitica O∶8. This led us to suggest that reduced cytotoxic potency may allow pathogen propagation within a shielded niche, leading to increased virulence. To test the relationship between cytotoxic potential and virulence, we replaced Y. pestis YopJ with YopP. The YopP-expressing Y. pestis strain exhibited high cytotoxic activity against macrophages in vitro. Following subcutaneous infection, this strain had reduced ability to colonize internal organs, was unable to induce septicemia and exhibited at least a 107-fold reduction in virulence. Yet, upon intravenous or intranasal infection, it was still as virulent as the wild-type strain. The subcutaneous administration of the cytotoxic Y. pestis strain appears to activate a rapid and potent systemic, CTL-independent, immunoprotective response, allowing the organism to overcome simultaneous coinfection with 10,000 LD50 of virulent Y. pestis. Moreover, three days after subcutaneous administration of this strain, animals were also protected against septicemic or primary pneumonic plague. Our findings indicate that an inverse relationship exists between the cytotoxic potential of Y. pestis and its virulence following subcutaneous infection. This appears to be associated with the ability of the engineered cytotoxic Y. pestis strain to induce very rapid, effective and long-lasting protection against bubonic and pneumonic plague. These observations have novel implications for the development of vaccines/therapies against Y. pestis and shed new light on the virulence strategies of Y. pestis in nature. 相似文献
85.
86.
Kiran S Nadella Motoyasu Saji Naduparambil K Jacob Emilia Pavel Matthew D Ringel Lawrence S Kirschner 《EMBO reports》2009,10(6):599-605
Proper regulation of the cAMP-dependent protein kinase (protein kinase A, PKA) is necessary for cellular homeostasis, and dysregulation of this kinase is crucial in human disease. Mouse embryonic fibroblasts (MEFs) lacking the PKA regulatory subunit Prkar1a show altered cell morphology and enhanced migration. At the molecular level, these cells showed increased phosphorylation of cofilin, a crucial modulator of actin dynamics, and these changes could be mimicked by stimulating the activity of PKA. Previous studies of cofilin have shown that it is phosphorylated primarily by the LIM domain kinases Limk1 and Limk2, which are under the control of the Rho GTPases and their downstream effectors. In Prkar1a−/− MEFs, neither Rho nor Rac was activated; rather, we showed that PKA could directly phosphorylate Limk1 and thus enhance the phosphorylation of cofilin. These data indicate that PKA is crucial in cell morphology and migration through its ability to modulate directly the activity of LIM kinase. 相似文献
87.
This article traces a critical change in the professional therapy of posttraumatic stress disorder (PTSD): from treatment
of a disorder borne by individuals to treatment of an anticipated disorder to be prevented by fortifying the entire population.
A community resilience program in the city of Sderot in southern Israel, which has been subjected to Qassam rockets by its
Palestinian neighbors across the border, serves as our case study. Drawing on an ethnographic study of this new therapeutic
program, we analyze how the social body that the professionals attempt to immunize against trauma was treated. In particular,
we follow the various practices used to expand the clinical. We found that the population was split into several groups on
a continuum between the clinical and the preclinical, each receiving different treatment. Moreover, the social body managed
according to this new form of PTSD was articulated through ethnic and geopolitical power relations between professionals from
the country’s center and professionals from its periphery, and between the professionals and the city’s residents. Finally,
we discuss how this Israeli case compares with other national sites of the growing globalization of PTSD, like Bali, Haiti
and Ethiopia, which anthropologists have been exploring in recent years. 相似文献
88.
Declarative and emotional memories are key to quality of life and day-to-day functioning. The absence of memory or the inability to recall memories properly in an emotional context leads to dysfunction but, paradoxically, memories that generate too much emotion can be equally disabling. 相似文献
89.
Identification and Biochemical Characterization of Molybdenum Cofactor-binding Proteins from Arabidopsis thaliana 总被引:1,自引:0,他引:1
Tobias Kruse Christian Gehl Mirco Geisler Markus Lehrke Phillip Ringel Stephan Hallier Robert H?nsch Ralf R. Mendel 《The Journal of biological chemistry》2010,285(9):6623-6635
The molybdenum cofactor (Moco) forms part of the catalytic center in all eukaryotic molybdenum enzymes and is synthesized in a highly conserved pathway. Among eukaryotes, very little is known about the processes taking place subsequent to Moco biosynthesis, i.e. Moco transfer, allocation, and insertion into molybdenum enzymes. In the model plant Arabidopsis thaliana, we identified a novel protein family consisting of nine members that after recombinant expression are able to bind Moco with KD values in the low micromolar range and are therefore named Moco-binding proteins (MoBP). For two of the nine proteins atomic structures are available in the Protein Data Bank. Surprisingly, both crystal structures lack electron density for the C terminus, which may indicate a high flexibility of this part of the protein. C-terminal truncated MoBPs showed significantly decreased Moco binding stoichiometries. Experiments where the MoBP C termini were exchanged among MoBPs converted a weak Moco-binding MoBP into a strong binding MoBP, thus indicating that the MoBP C terminus, which is encoded by a separate exon, is involved in Moco binding. MoBPs were able to enhance Moco transfer to apo-nitrate reductase in the Moco-free Neurospora crassa mutant nit-1. Furthermore, we show that the MoBPs are localized in the cytosol and undergo protein-protein contact with both the Moco donor protein Cnx1 and the Moco acceptor protein nitrate reductase under in vivo conditions, thus indicating for the MoBPs a function in Arabidopsis cellular Moco distribution. 相似文献
90.