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排序方式: 共有385条查询结果,搜索用时 15 毫秒
61.
Masoud F. Tavazoie Ilana Pollack Raissa Tanqueco Benjamin N. Ostendorf Bernardo S. Reis Foster C. Gonsalves Isabel Kurth Celia Andreu-Agullo Mark L. Derbyshire Jessica Posada Shugaku Takeda Kimia N. Tafreshian Eric Rowinsky Michael Szarek Roger J. Waltzman Elizabeth A. Mcmillan Connie Zhao Monica Mita Sohail F. Tavazoie 《Cell》2018,172(4):825-840.e18
62.
Charles J. O'Kelly Michael E. Sieracki Edward C. Thier Ilana C. Hobson 《Journal of phycology》2003,39(5):850-854
The smallest known eukaryote, Ostreococcus tauri Courties et Chrétiennot-Dinet, was first reported as the dominant picoplankter in a French lagoon known for its diverse phytoplankton community and high oyster productivity. Long-term seasonal blooms of this picoeukaryote were observed in association with stable plankton communities. On 5 June 2001, a distinctive monotypic picoplankton bloom was detected by flow cytometry as part of an ongoing study of "brown tide" ( Aureococcus anophagefferens ) bloom initiation in Long Island bays. The bloom reached a concentration of 5 × 105 cells·mL−1 in West Neck Bay and lasted less than 2 weeks. Epifluorescence microscopy and TEM indicated that the bloom organism was an Ostreococcus -like picoalga, the first ever observed in a Long Island bay. Many cells of this alga contained numerous virus-like particles. The Ostreococcus -like picoalga, which resembles O. tauri , was rare in samples collected the following week. Instead, a substantial increase in the Synechococcus population was observed. Such rapid population changes have not previously been reported for Ostreococcus . Viral lysis and grazing by heterotrophic nanoflagellates may have contributed to the rapid decline of the Ostreococcus -like cells in West Neck Bay. 相似文献
63.
64.
Proteomic Profiling of Recombinant Escherichia coli in High-Cell- Density Fermentations for Improved Production of an Antibody Fragment Biopharmaceutical 下载免费PDF全文
Ilana S. Aldor Denise C. Krawitz William Forrest Christina Chen Julie C. Nishihara John C. Joly Kathleen M. Champion 《Applied microbiology》2005,71(4):1717-1728
By using two-dimensional polyacrylamide gel electrophoresis, a proteomic analysis over time was conducted with high-cell-density, industrial, phosphate-limited Escherichia coli fermentations at the 10-liter scale. During production, a recombinant, humanized antibody fragment was secreted and assembled in a soluble form in the periplasm. E. coli protein changes associated with culture conditions were distinguished from protein changes associated with heterologous protein expression. Protein spots were monitored quantitatively and qualitatively. Differentially expressed proteins were quantitatively assessed by using a t-test method with a 1% false discovery rate as a significance criterion. As determined by this criterion, 81 protein spots changed significantly between 14 and 72 h (final time) of the control fermentations (vector only). Qualitative (on-off) comparisons indicated that 20 more protein spots were present only at 14 or 72 h in the control fermentations. These changes reflected physiological responses to the culture conditions. In control and production fermentations at 72 h, 25 protein spots were significantly differentially expressed. In addition, 19 protein spots were present only in control or production fermentations at this time. The quantitative and qualitative changes were attributable to overexpression of recombinant protein. The physiological changes observed during the fermentations included the up-regulation of phosphate starvation proteins and the down-regulation of ribosomal proteins and nucleotide biosynthesis proteins. Synthesis of the stress protein phage shock protein A (PspA) was strongly correlated with synthesis of a recombinant product. This suggested that manipulation of PspA levels might improve the soluble recombinant protein yield in the periplasm for this bioprocess. Indeed, controlled coexpression of PspA during production led to a moderate, but statistically significant, improvement in the yield. 相似文献
65.
Ilana Moscatelli Enrico Pierantozzi Antonella Camaioni Gregorio Siracusa Luisa Campagnolo 《Experimental cell research》2009,315(18):3220-3232
Neurotrophins and their receptors are known to play a role in the proliferation and survival of many different cell types of neuronal and non-neuronal lineages. In addition, there is much evidence in the literature showing that the p75 neurotrophin receptor (p75NTR), alone or in association with members of the family of Trk receptors, is expressed in a wide variety of stem cells, although its role in such cells has not been completely elucidated. In the present work we have investigated the expression of p75NTR and Trks in totipotent and pluripotent cells, the mouse pre-implantation embryo and embryonic stem and germ cells (ES and EG cells). p75NTR and TrkA can be first detected in the blastocyst from which ES cell lines are derived. Mouse ES cells retain p75NTR/TrkA expression. Nerve growth factor is the only neurotrophin able to stimulate ES cell growth in culture, without affecting the expression of stem cell markers, alkaline phosphatase, Oct4 and Nanog. Such proliferation effect was blocked by antagonizing either p75NTR or TrkA. Interestingly, immunoreactivity to anti-p75NTR antibodies is lost upon ES cell differentiation. The expression pattern of neurotrophin receptors in murine ES cells differs from human ES cells, that only express TrkB and C, and do not respond to NGF. In this paper we also show that, while primordial germ cells (PGC) do not express p75NTR, when they are made to revert to an ES-like phenotype, becoming EG cells, expression of p75NTR is turned on. 相似文献
66.
The purpose of this work was to evaluate the effects of ethylene action blockade and cold storage on the ripening of ‘Golden’
papaya fruit. Papayas harvested at maturity stage 1 (up to 15% yellow skin) were evaluated. Half of the fruits, whether treated
or not treated with 100 nL L−1 of 1-methylcyclopropene (1-MCP), were stored at 23°C, while the other half were stored at 11°C for 20 days prior to being
stored at 23°C. Non-refrigerated fruits receiving 1-MCP application presented a reduction in respiratory activity, ethylene
production, skin color development and pectinmethylesterase activity. Even with a gradual increase in ethylene production
at 23°C, fruits treated with 1-MCP maintained a high firmness, but presented a loss of green skin color. Cold storage caused
a decrease in ethylene production when fruits were transferred to 23°C. The results suggest that pulp softening is more dependent
on ethylene than skin color development, and that some processes responsible for loss of firmness do not depend on ethylene. 相似文献
67.
68.
Photosynthetic oxygen-evolving microorganisms contend with continuous self-production of molecular oxygen and reactive oxygen species. The deleterious effects of reactive oxygen species are exacerbated for cyanobacterial nitrogen-fixers (diazotrophs) due to the innate sensitivity of nitrogenase to oxygen. This renders incompatible the processes of oxygen-evolving photosynthesis and N-fixation. We examined total antioxidative potential of various diazotrophic and non-diazotrophic cyanobacteria. We focused on Trichodesmium spp., a bloom-forming marine diazotroph that contributes significantly to global nitrogen fixation. Among the species tested, Trichodesmium possessed the highest antioxidant activity. Moreover, while proteins constituted the dominant antioxidative component of all other cyanobacteria tested, Trichodesmium was unique in that small-molecule natural products provided the majority of antioxidant activity, while proteins constituted only 13% of total antioxidant activity. Bioassay-guided fractionation followed by high-performance liquid chromatography profiling of antioxidant purified fractions identified the highly potent antioxidant all- trans -β-carotene, and small amounts of 9- cis -β-carotene and retinyl palmitate. Search of the Trichodesmium genome identified protein sequences homologous to key enzymes in the β-carotene to retinyl palmitate biosynthetic pathway, including 33–37% identity to lecithin retinol acyltransferase. The present study demonstrates the importance of carotenoids in Trichodesmium 's arsenal of defensive compounds against oxidative damage and protection of nitrogenase from oxygen and its radicals. 相似文献
69.
Shahar Amitai Ilana Kolodkin-Gal Mirit Hananya-Meltabashi Ayelet Sacher Hanna Engelberg-Kulka 《PLoS genetics》2009,5(3)
The Escherichia coli mazEF module is one of the most thoroughly studied toxin–antitoxin systems. mazF encodes a stable toxin, MazF, and mazE encodes a labile antitoxin, MazE, which prevents the lethal effect of MazF. MazF is an endoribonuclease that leads to the inhibition of protein synthesis by cleaving mRNAs at ACA sequences. Here, using 2D-gels, we show that in E. coli, although MazF induction leads to the inhibition of the synthesis of most proteins, the synthesis of an exclusive group of proteins, mostly smaller than about 20 kDa, is still permitted. We identified some of those small proteins by mass spectrometry. By deleting the genes encoding those proteins from the E. coli chromosome, we showed that they were required for the death of most of the cellular population. Under the same experimental conditions, which induce mazEF-mediated cell death, other such proteins were found to be required for the survival of a small sub-population of cells. Thus, MazF appears to be a regulator that induces downstream pathways leading to death of most of the population and the continued survival of a small sub-population, which will likely become the nucleus of a new population when growth conditions become less stressful. 相似文献
70.