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Hadi N Yehia Rockford K Draper Carole Mikoryak Erin Kate Walker Pooja Bajaj Inga H Musselman Meredith C Daigrepont Gregg R Dieckmann Paul Pantano 《Journal of nanobiotechnology》2007,5(1):8-17
This work concerns exposing cultured human epithelial-like HeLa cells to single-walled carbon nanotubes (SWNTs) dispersed
in cell culture media supplemented with serum. First, the as-received CoMoCAT SWNT-containing powder was characterized using
scanning electron microscopy and thermal gravimetric analyses. Characterizations of the purified dispersions, termed DM-SWNTs,
involved atomic force microscopy, inductively coupled plasma – mass spectrometry, and absorption and Raman spectroscopies.
Confocal microRaman spectroscopy was used to demonstrate that DM-SWNTs were taken up by HeLa cells in a time- and temperature-dependent
fashion. Transmission electron microscopy revealed SWNT-like material in intracellular vacuoles. The morphologies and growth
rates of HeLa cells exposed to DM-SWNTs were statistically similar to control cells over the course of 4 d. Finally, flow
cytometry was used to show that the fluorescence from MitoSOX™ Red, a selective indicator of superoxide in mitochondria, was
statistically similar in both control cells and cells incubated in DM-SWNTs. The combined results indicate that under our
sample preparation protocols and assay conditions, CoMoCAT DM-SWNT dispersions are not inherently cytotoxic to HeLa cells.
We conclude with recommendations for improving the accuracy and comparability of carbon nanotube (CNT) cytotoxicity reports. 相似文献
644.
Hadi Nazem-Bokaee Dayue Chen Sean Michael O'Donnell Andrew L. Zydney 《Biotechnology and bioengineering》2019,116(8):2010-2017
Virus filtration remains a critical step in the downstream process for the production of monoclonal antibodies and other mammalian cell-derived biotherapeutics. Recent studies have shown large differences in virus capture behavior of different virus filters, although the origin of these differences is still unclear. The objective of this study was to use confocal and scanning electron microscopy to directly evaluate the capture of virus-size nanoparticles in Planova 20N and BioEX hollow-fiber virus filters. Confocal images of fluorescent nanoparticles were quantified using ImageJ image processing software based on the measured fluorescence intensity of the labeled nanoparticles. Nanoparticle capture by the Planova BioEX was independent of transmembrane pressure from 10 to 45 psi. In contrast, the Planova 20N showed significant differences in nanoparticle capture profile at low pressure, consistent with literature data showing virus breakthrough under these conditions. Images obtained after a process interruption show significant migration of previously captured nanoparticles in the Planova 20N filters but not in the BioEX. These results provide important insights into the nature of virus capture in different virus filters and its dependence on the underlying structure of the virus filtration membranes. 相似文献
645.
The EcoP15 restriction endonuclease forms complexes at specific sites on unmodified DNA both in the presence and in the absence of S-adenosyl-l-methionine. ATP acts as an allosteric effector of EcoP15 and induces DNA cleavage followed by release of the enzyme from the DNA. The efficiency of endonucleolytic scission varies from site to site. The nucleotide sequences at sites that are cleaved at a high frequency were compared. 相似文献
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Bahadori Mohammed Hadi Al-Tiraihi Taki Valojerdi Mujtaba Rezazadeh 《Brain Cell Biology》2001,30(2):125-130
Transection of a peripheral nerve in neonatal rats induces death of the axotomized neurons which may be due to either necrosis or apoptosis. In the present investigation, neuronal cell death in L5 dorsal root ganglion was evaluated after unilateral sciatic nerve transection in rats at 1, 3, 5, 7 and 10 days age. After 5 days, right (experimental) and left (control) dorsal root ganglia in all groups were removed, fixed, processed and embedded for either light or electron microscopy. Normal nucleoli were counted in paraffin embedded serial sections, and correction factors for split and multiple nucleoli were applied as well as the physical disector. The number of neurons in the right dorsal root ganglia, as compared with the controls, was significantly lower in all groups, and the percentage of the reduction at 1, 3, 5, 7 and 10 days was 32.4, 27.2, 23.8, 22.8 and 21.8% respectively. On the other hand, the results of neuronal counts using the disector method showed 34.0, 25.7, 20.2, 20.0 and 14.2% reduction in the number of neurons at 1, 3, 5, 7 and 10 days, respectively. The microscopic and ultrastructural results indicated that there were typical morphological changes similar to those of apoptosis, including condensed basophilic nuclei, formation of nuclear caps, cell shrinkage and apoptotic body formation. We concluded that there is an increase in apoptosis in dorsal root ganglia following sciatic nerve axotomy with the greatest neuronal loss on postnatal day 1. 相似文献
649.
Influence of Oxides on the Stress Evolution and Reversibility during SnOx Conversion and Li‐Sn Alloying Reactions
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The effect of varying the oxygen content in Sn and SnOx films during potential dependent SnOx conversion reactions and LiySn alloying relevant to Li ion battery anodes is examined. For metallic Sn films, the stresses and stability of the films are controlled by Li alloying reactions. Small, non‐contacting separated Sn particles exhibit higher electrochemical stability relative to more continuous polycrystalline films with larger particles. Metallic Sn particles develop tensile stress during LiySn de‐alloying as porous structures are formed. The amount of stress associated with lithiation and delithiation of well‐separated metallic particles decreases as a porous, easy to lithiate, material forms with cycling. During the lithiation of oxides, conversion reactions (SnOx → Sn) and the lithiation of the metallic Sn control the stress responses of the films, leading to highly potential‐dependent stress development. In particular, evidence for a multistep electrochemical mechanism, in which partially reversible lithiation of the oxygen‐containing phases is conjoined with a fully reversible lithiation of the metallic phases of the Sn, is found. The electrochemical stress analysis provides new insight into these mechanisms and delineates the extent of the reversibility of lithiation and conversion reactions of oxides. 相似文献
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AbstractHuman health has been identified to be affected more significantly by indoor air quality. Among numerous pollutants present in indoor air, formaldehyde (FA) is of great concern because of its highly hazardous nature. The concentrations of FA were determined from 20 newly decorated homes in the city of Gonabad, Iran during 2015. It was found that the indoor air levels of FA in all the sampled houses were exceptionally high in the range of 21 to 360 µg/m3 (mean of 149.3 µg/m3). If the 24-h average concentrations of FA measured from those sites were concerned, nearly 40% of them were seen to exceed the WHO guideline values (i.e., 100 µg/m3). One of the important reasons for the high concentrations could be low air exchange rates in those houses (e.g., from 0.18 to 0.37?h?1), high levels of humidity in the newly decorating houses and stronger sources in the indoor environment. Furthermore, its pollution in homes with natural ventilation was seen to be much higher than those of mechanical ventilation. Due to high levels of indoor FA, more effective control procedures should be developed and employed to reduce the risk associated with formaldehyde exposure. 相似文献