全文获取类型
收费全文 | 364篇 |
免费 | 52篇 |
国内免费 | 2篇 |
出版年
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 26篇 |
2012年 | 11篇 |
2011年 | 16篇 |
2010年 | 17篇 |
2009年 | 8篇 |
2008年 | 18篇 |
2007年 | 17篇 |
2006年 | 23篇 |
2005年 | 11篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 6篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1993年 | 3篇 |
1992年 | 13篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 6篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1968年 | 3篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有418条查询结果,搜索用时 281 毫秒
381.
Invasive characteristics of neural crest cells in vitro 总被引:1,自引:0,他引:1
K R Gehlsen M J Hendrix 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》1987,1(1):16-21
An investigation of the invasiveness of avian neural crest cells and neural crest-derived melanocytes through a human amniotic basement membrane (BM) was undertaken. Avian neural tube explants or derived melanocyte populations were seeded directly onto BMs in membrane invasion culture system (MICS) chambers for periods of 24, 48, and 72 h. In 36 experimental trials for each group, neither neural crest nor neural crest-derived melanocytes were observed to have invaded the BMs. In concert with these studies, coculturing of B16F10 murine melanoma cells with avian neural crest-derived melanocytes was performed in MICS chambers. Under these experimental conditions, the neural crest-derived melanocytes were able to successfully invade the BMs and to a greater extent than the B16F10 tumor cells. These data suggest that neural crest cells and neural crest-derived melanocytes do not have the ability to invade the BM alone; however, they can be induced to be invasive when cocultured in the presence of B16F10 cells. Alternatively, the B16F10 cells may create weaknesses within the BM that facilitate migration of the pigmented crest cells. 相似文献
382.
383.
Differentiation of Coxiella burnetii isolates by analysis of restriction-endonuclease-digested DNA separated by SDS-PAGE. 总被引:5,自引:0,他引:5
Thirty-two isolates of Coxiella burnetii collected from various hosts ranging from arthropods to man were compared by restriction endonuclease (RE) digestion patterns of chromosomal DNA using SDS-PAGE. SDS-PAGE provided better DNA fragment separation than agarose gel electrophoresis and enabled the differentiation of these isolates into six distinct groups on the basis of DNA restriction fingerprints. Two groups of chronic disease isolates could be distinguished, each having unique RE digestion patterns of chromosomal DNA. Three similar but distinct RE digestion patterns were seen among the group of acute disease isolates. Three additional isolates included in this study exhibited a unique RE digestion pattern and also had a unique plasmid type, designated QpDG. DNA-DNA hybridization on selected isolates quantified the relatedness between several groups and supported the classification of these groups as distinct strains. 相似文献
384.
385.
Alicia M. Hendrix Kathi A. Lefebvre Lori Quakenbush Anna Bryan Raphaela Stimmelmayr Gay Sheffield Gabriel Wisswaesser Maryjean L. Willis Emily K. Bowers Preston Kendrick Elizabeth Frame Thomas Burbacher David J. Marcinek 《Marine Mammal Science》2021,37(4):1292-1308
Domoic acid (DA) and saxitoxin (STX)-producing algae are present in Alaskan seas, presenting exposure risks to marine mammals that may be increasing due to climate change. To investigate potential increases in exposure risks to four pagophilic ice seal species (Erignathus barbatus, bearded seals; Pusa hispida, ringed seals; Phoca largha, spotted seals; and Histriophoca fasciata, ribbon seals), this study analyzed samples from 998 seals harvested for subsistence purposes in western and northern Alaska during 2005–2019 for DA and STX. Both toxins were detected in bearded, ringed, and spotted seals, though no clinical signs of acute neurotoxicity were reported in harvested seals. Bearded seals had the highest prevalence of each toxin, followed by ringed seals. Bearded seal stomach content samples from the Bering Sea showed a significant increase in DA prevalence with time (logistic regression, p = .004). These findings are consistent with predicted northward expansion of DA-producing algae. A comparison of paired samples taken from the stomachs and colons of 15 seals found that colon content consistently had higher concentrations of both toxins. Collectively, these results suggest that ice seals, particularly bearded seals (benthic foraging specialists), are suitable sentinels for monitoring HAB prevalence in the Pacific Arctic and subarctic. 相似文献
386.
Our study was designed to examine how components of complex mixtures can
inhibit the binding of other components to receptor sites in the olfactory
system of the spiny lobster Panulirus argus. Biochemical binding assays
were used to study how two- to six-component mixtures inhibit binding of
the radiolabeled odorants taurine, L-glutamate and
adenosine-5'-monophosphate to a tissue fraction rich in dendritic membrane
of olfactory receptor neurons. Our results indicate that binding inhibition
by mixtures can be large and is dependent on the nature of the odorant
ligand and on the concentration and composition of the mixture. The binding
inhibition by mixtures of structurally related components was generally
predicted using a competitive binding model and binding inhibition data for
the individual components. This was not the case for binding inhibition by
most mixtures of structurally unrelated odorants. The binding inhibition
for these mixtures was generally smaller than that for one or more of their
components, indicating that complex binding interactions between components
can reduce their ability to inhibit binding. The magnitude of binding
inhibition was influenced more by the mixture's precise composition than by
the number of components in it, since mixtures with few components were
sometimes more inhibitory than mixtures with more components. These
findings raise the possibility that complex binding interactions between
components of a mixture and their receptors may shape the output of
olfactory receptor neurons to complex mixtures.
相似文献
387.
388.
389.
Tubulin and MAP2 regulate the PCSL phosphatase activity. A possible new role for microtubular proteins 总被引:1,自引:0,他引:1
C Jessus J Goris X Cayla J Hermann P Hendrix R Ozon W Merlevede 《European journal of biochemistry》1989,180(1):15-22
Tubulin can stimulate specifically the aryl phosphatase activity of the low-Mr polycation-stimulated (PCSL) phosphatase, measured as p-nitrophenyl phosphatase activity, or using reduced carboxamidomethylated and maleylated (RCM) lysozyme, phosphorylated on tyrosyl residues, as a substrate. This stimulation is independent of the degree of polymerization of tubulin (A50 = 60 nM) and is due to an increase in Vmax. It is mechanistically different from the ATP-induced activation and resistant to heat and trypsin treatment. Chymotrypsin destroys the stimulatory effect of tubulin. The polycation-stimulated phosphorylase phosphatase activity is inhibited by tubulin, probably by a polycation/polyanion interaction. The microtubule-associated protein, MAP2, is inhibitory to the p-nitrophenyl phosphatase activity and tubulin can eliminate this inhibitory effect. MAP2 also inhibits the polycation-stimulated phosphorylase phosphatase activity. 相似文献
390.
R E Seftor E A Seftor A E Cress M J Hendrix 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》1990,3(1):44-48
Three human melanoma cell lines of differing invasive and metastatic potentials were cultured on either a plastic surface or a denuded amniotic basement membrane, and alterations in their cell surface proteins, invasive profiles, and the presence or absence of the 69 Kd high-affinity metastasis-associated laminin receptor were examined. Our data indicate that the labeled, precipitable cell surface proteins are different from the three cell lines when they are cultured on the same substrate, and change when the cells are cultured on a different substrate. Furthermore, the invasive potential (as measured in the in vitro Membrane Invasion Culture System) is decreased for all of the cell lines after culturing the cells on a basement membrane matrix compared to a plastic surface. Finally, we show that the 69 Kd high-affinity metastasis-associated laminin receptor can be isolated from all three cell lines cultured on the two different substrates by labeling the cell surface with trinitrobenzene sulfonic acid and immunoprecipitating these targeted proteins. 相似文献