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21.
22.
Peripheral Lipopolysaccharide Challenge Induces Long‐Term Changes in Tyrosine Hydroxylase Regulation in the Adrenal Medulla
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Lin Kooi Ong Larisa Bobrovskaya Frederick R. Walker Trevor A. Day Phillip W. Dickson Peter R. Dunkley 《Neurochemical research》2011,36(1):27-33
Tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, is regulated acutely by protein phosphorylation
and chronically by protein synthesis. No studies have systematically investigated the phosphorylation of these sites in vivo
in response to stressors. We specifically investigated the phosphorylation of TH occurring within the first 24 h in response
to the social defeat stress in the rat adrenal, the locus coeruleus, substantia nigra and ventral tegmental area. Five groups
were investigated; home cage control (HCC), two groups that underwent social defeat (SD+) which were sacrificed either 10 min
or 24 h after the end of the protocol and two groups that were put into the cage without the resident being present (SD−)
which were sacrificed at time points identical to the SD+. We found at 10 min there were significant increases in serine 40
and 31 phosphorylation levels in the locus coeruleus in SD+ compared to HCC and increases in serine 40 phosphorylation levels
in the substantia nigra in SD+ compared to SD−. We found at 24 h there were significant increases in serine 19 phosphorylation
levels in the ventral tegmental area in SD+ compared to HCC and decreases in serine 40 phosphorylation levels in the adrenal
in SD+ compared to SD−. These findings suggest that the regulation of TH phosphorylation in different catecholamine-producing
cells varies considerably and is dependent on both the nature of the stressor and the time at which the response is analysed. 相似文献
25.
Dunkley Katie Ellison Amy R. Mohammed Ryan S. van Oosterhout Cock Whittey Kathryn E. Perkins Sarah E. Cable Jo 《Coral reefs (Online)》2019,38(2):321-330
Coral Reefs - Cleaning interactions, which involve a cleaner removing ectoparasites and other material from the body of a heterospecific (client), are iconic symbiotic interactions observed on... 相似文献
26.
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Isabel S. Fenton Paul N. Pearson Tom Dunkley Jones Alexander Farnsworth Daniel J. Lunt Paul Markwick Andy Purvis 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2016,371(1691)
The Cenozoic planktonic foraminifera (PF) (calcareous zooplankton) have arguably the most detailed fossil record of any group. The quality of this record allows models of environmental controls on macroecology, developed for Recent assemblages, to be tested on intervals with profoundly different climatic conditions. These analyses shed light on the role of long-term global cooling in establishing the modern latitudinal diversity gradient (LDG)—one of the most powerful generalizations in biogeography and macroecology. Here, we test the transferability of environment-diversity models developed for modern PF assemblages to the Eocene epoch (approx. 56–34 Ma), a time of pronounced global warmth. Environmental variables from global climate models are combined with Recent environment–diversity models to predict Eocene richness gradients, which are then compared with observed patterns. The results indicate the modern LDG—lower richness towards the poles—developed through the Eocene. Three possible causes are suggested for the mismatch between statistical model predictions and data in the Early Eocene: the environmental estimates are inaccurate, the statistical model misses a relevant variable, or the intercorrelations among facets of diversity—e.g. richness, evenness, functional diversity—have changed over geological time. By the Late Eocene, environment–diversity relationships were much more similar to those found today. 相似文献
28.
Mutants of Bacillus species isolated on the basis of protonophore resistance are deficient in fatty acid desaturase activity.
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The fatty acid desaturase activity in cell extracts of Bacillus subtilis was characterized and found to be O2 dependent, NADH dependent, and cyanide sensitive. In cell fractionation studies, only 10% of the desaturase activity was recovered in the membrane fraction; the addition of cytosolic factors, which by themselves were devoid of activity, restored membrane activity to the level found in the unfractionated cell extracts. NADH was preferred over NADPH as an electron donor, and palmitoyl-coenzyme A was used preferentially over stearoyl-coenzyme A as the straight-chain fatty acid substrate. An increase in desaturase activity was observed when either the growth or the assay temperature was lowered from 37 to 20 degrees C, although the assay temperature appeared to be the more important parameter. Three protonophore-resistant mutants of B. subtilis and a comparable mutant of Bacillus megaterium had been found to possess reduced levels of unsaturated fatty acids in their membrane phospholipids; their protonophore resistance was abolished when grown in the presence of an unsaturated fatty acid supplement. All of these strains were found to be either significantly deficient in or totally lacking desaturase activity in comparison with their wild-type parent strains. Full, protonophore-sensitive revertants of the mutants had levels of desaturase activity comparable to those of the wild-type. Temperature-sensitive revertants of two of the mutants, which grew at 32 degrees C but not at 26 degrees C in the presence of protonophore, exhibited desaturase activity comparable to that of the wild-type at 26 degrees C but lacked activity at 32 degrees C. These results indicate that the biochemical basis for protonophore resistance in these Bacillus mutants is a fatty acid desaturase deficiency. 相似文献
29.
Facultative alkaliphiles lack fatty acid desaturase activity and lose the ability to grow at near-neutral pH when supplemented with an unsaturated fatty acid. 总被引:2,自引:2,他引:0
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Two obligate alkaliphiles were found to have high levels of fatty acid desaturase, whereas two facultative alkaliphiles had no detectable activity. Supplementation of the growth medium of one facultative strain with palmitoleic acid, but not palmitic acid, at pH 7.5 inhibited growth. The obligate strain outgrows the facultative strain in a chemostat at a very high pH, whereas the converse is true at a pH of 7.5, and the two strains grow equally well at pH 9.0. Thus, the obligate strain is compromised at a near-neutral pH but is better adapted than a related facultative alkaliphile to an extremely alkaline pH. 相似文献
30.
Aamir Ahmad Shadan Ali Alia Ahmed Azfur S. Ali Avraham Raz Wael A. Sakr KM Wahidur Rahman 《PloS one》2013,8(1)
Herceptin failure is a major clinical problem in breast cancer. A subset of breast cancer patients with high HER-2/neu levels eventually experience metastatic disease progression when treated with Herceptin as a single agent. Mechanistic details of development of this aggressive disease are not clear. Therefore, there is a dire need to better understand the mechanisms by which drug resistance develops and to design new combined treatments that benefit patients with aggressive breast cancer and have minimal toxicity. We hypothesized that 3, 3′-diindolylmethane (DIM), a non-toxic agent can be combined with Herceptin to treat breast cancers with high levels of HER-2/neu. Here, we evaluated the effects of Herceptin alone and in combination with DIM on cell viability, apoptosis and clonogenic assays in SKBR3 (HER-2/neu-expressing) and MDA-MB-468 (HER-2/neu negative) breast cancer cells. We found that DIM could enhance the effectiveness of Herceptin by significantly reducing cell viability, which was associated with apoptosis-induction and significant inhibition of colony formation, compared with single agent treatment. These results were consistent with the down-regulation of Akt and NF-kB p65. Mechanistic investigations revealed a significant upregulation of miR-200 and reduction of FoxM1 expression in DIM and Herceptin-treated breast cancer cells. We, therefore, transfected cells with pre-miR-200 or silenced FoxM1 in these cells for understanding the molecular mechanism involved. These results provide experimental evidence, for the first time, that DIM plus Herceptin therapy could be translated to the clinic as a therapeutic modality to improve treatment outcome of patients with breast cancer, particularly for the patients whose tumors express high levels of HER-2/neu. 相似文献