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1.
The role of fluorinated pyrimidine analogues in the induction of the in vitro expression of the fragile X chromosome 总被引:1,自引:1,他引:0
Summary The modes of action of 5-fluoro-2-deoxyuridine (FdUrd) and 5-fluoro-2-deoxycytidine (FdCyd) were studied in PHA-stimulated lymphocytes from normal volunteer donors and a fragile X patient. In both cell types, FdUrd and FdCyd inhibited cell proliferation at concentrations of 3x10-8
M. Thymidylate synthetase was identified as the decisive target for the action of both FdUrd and FdCyd, as judged from the following observations: First, addition of thymidine to the culture medium was able to counteract both FdUrd and FdCyd toxicities, whereas addition of dCyd had no observable effect. Second, inhibition of the in situ thymidylate synthetase activity measured as an increase in the level of [3H]-dThd incorporation coincided with the inhibition of cell proliferation. Third, the inhibition of the thymidylate synthetase-dependent incorporation of [3H]-dUrd into newly synthesized DNA coincided with the inhibition of cell proliferation. The effects of FdUrd and FdCyd on the in vitro expression of fragile site Xq27 of fragile X chromosomes was shown to be based on the depletion of the intracellular pool of thymidine-5-monophosphate (dTMP), as fudged from the following observations: First, both the FdUrd- and FdCyd-dependent induction of site Xq27 coincided with the antiproliferative effects of the respective fluoropyrimidines. Second, addition of thymidine (dThd) to the culture medium both prevented the expression of site Xq27 and neutralized the cytotoxicity of FdUrd and of FdCyd. On the basis of these findings, we provide further evidence for the concept that the fragile X site is located in an AT-rich region. 相似文献
2.
Jan Schripsema Annemarie H. Meijer Frank van Iren Hens J. G. ten Hoopen Robert Verpoorte 《Plant Cell, Tissue and Organ Culture》1990,22(1):55-64
A simple non-invasive method for the characterization of growth of a plant cell suspension in a single culture flask is given. The dissimilation of sugars by a cell-culture causes a loss of weight of the contents of the culture flask, and can therefore be used to follow the growth in that single culture flask. Because a correction for water evaporation is necessary, accurate results can only be obtained when a stable closure is used (e.g. Silicosen T-type plugs). The dissimilation curves obtained in this way were correlated to the concentration of sugars in the medium, the dry weight and the fresh weight. From these correlations the amount of intracellularly stored carbohydrates could be estimated. Rate constants for CO2-diffusion were determined for different types of closure. These values allowed the estimation of CO2 levels inside the culture flasks from the dissimilation curves (CO2 release curves). The dissimilation curves obtained using this method can easily be related to other types of growth curves. Different growth-phases can be clearly distinguished, e.g. lag-phase, exponential growth-phase and stationary-phase. 相似文献
3.
Jacques J. H. Hens Marina De Wit Lodewijk V. Dekker Frans Boomsma A. Beate Oestreicher Frank Margolis† Willem Hendrik Gispen Pierre N. E. De Graan 《Journal of neurochemistry》1993,60(4):1264-1273
Abstract: The involvement of B-50, protein kinase C (PKC), and PKC-mediated B-50 phosphorylation in the mechanism of Ca2+-induced noradrenaline (NA) release was studied in highly purified rat cerebrocortical synaptosomes permeated with streptolysin-O. Under optimal permeation conditions, 12% of the total NA content (8.9 pmol of NA/mg of synaptosomal protein) was released in a largely (>60%) ATP-dependent manner as a result of an elevation of the free Ca2+ concentration from 10?8 to 10?5M Ca2+ The Ca2+ sensitivity in the micromolar range is identical for [3H]NA and endogenous NA release, indicating that Ca2+-induced [3H]NA release originates from vesicular pools in noradrenergic synaptosomes. Ca2+-induced NA release was inhibited by either N- or C-terminal-directed anti-B-50 antibodies, confirming a role of B-50 in the process of exocytosis. In addition, both anti-B-50 antibodies inhibited PKC-mediated B-50 phosphorylation with a similar difference in inhibitory potency as observed for NA release. However, in a number of experiments, evidence was obtained challenging a direct role of PKC and PKC-mediated B-50 phosphorylation in Ca2+-induced NA release. PKC pseudosubstrate PKC19-36, which inhibited B-50 phosphorylation (IC50 value, 10?5M), failed to inhibit Ca2+-induced NA release, even when added before the Ca2+ trigger. Similar results were obtained with PKC inhibitor H-7, whereas polymyxin B inhibited B-50 phosphorylation as well as Ca2+-induced NA release. Concerning the Ca2+ sensitivity, we demonstrate that PKC-mediated B-50 phosphorylation is initiated at a slightly higher Ca2+ concentration than NA release. Moreover, phorbol ester-induced PKC down-regulation was not paralleled by a decrease in Ca2+-induced NA release from streptolysin-O-permeated synaptosomes. Finally, the Ca2+- and phorbol ester-induced NA release was found to be additive, suggesting that they stimulate release through different mechanisms. In summary, we show that B-50 is involved in Ca2+-induced NA release from streptolysin-O-permeated synaptosomes. Evidence is presented challenging a role of PKC-mediated B-50 phosphorylation in the mechanism of NA exocytosis after Ca2+ influx. An involvement of PKC or PKC-mediated B-50 phosphorylation before the Ca2+ trigger is not ruled out. We suggest that the degree of B-50 phosphorylation, rather than its phosphorylation after PKC activation itself, is important in the molecular cascade after the Ca2+ influx resulting in exocytosis of NA. 相似文献
4.
Michael Keßler Hens J.G. ten Hoopen Josef J. Heijnen Shintaro Furusaki 《Biotechnology Techniques》1997,11(7):507-510
Despite the same mean volumetric power input of 19 and 47 W/m 3 , the specific oxygen uptake rate (OUR S ) of strawberry ( Fragaria ananassa) cell suspensions was higher in bioreactors equipped with a Rushton Turbine (4.4 and 6.2 3 10 -5 mol O 2 /kg.s) than with an anchor stirrer (2.5 and 4.6 3 10 -5 mol O 2kg.s). The increase in OUR S was caused by stress-activated respiration and appeared to be correlated with the locally dissipated power input. OUR S was corrected for the increase in surface through aggregate break-up and reached a maximum of 6.0 3 10 -5 mol O 2kg.s when agitating with approximately 200 kW/m 3 locally dissipated power input. 相似文献
5.
"Generalized distances" between centromeres were statistically analyzed (chi2 test) on 50 normal female trypsin-banded metaphase figures. This study revealed that the homologous chromosomes of the pairs 13, 17, 14, and 21 lie closer together than would be expected by a reference distribution, and this in a statistically significant way. The same relative position was demonstrated for the chromosome groups 13-14, 13-21, 14-21, 15-22, and 14-22. Evidences were collected that also showed that homologous chromosomes of the pairs 1, 19, and 20 and the chromosome groups 15-21, 13-15, and 18-20 tend to lie closer together. Giving a functional interpretation to the phenomenon of non-random distribution of chromosomes in metaphase figures, it may be suggested that the chromosomes 13, 14, and 21 are involved in the organization of the human nucleolar organizers, more frequently than the other D- and G-group chromosomes. 相似文献
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9.
Janaka?WeragodaEmail author Rohini?Seneviratne Manuj?C.?Weerasinghe SM?Wijeyaratne 《BMC research notes》2016,9(1):508
Background
Peripheral artery disease (PAD) is an important global health problem and contributes to notable proportion of morbidity and mortality. This particular manifestation of systemic atherosclerosis is largely under diagnosed and undertreated. For sustainable preventive strategies in a country, it is mandatory to identify country-specific risk factors. We intended to assess the risk factors of PAD among adults aged 40–74 years.Methods
This case control study was conducted in 2012–2013 in Sri Lanka. Seventy-nine cases and 158 controls in the age group of 40–74 years were selected for the study in order to have case to control ratio 1:2. The criterion for selecting cases and control was based on Ankle brachial pressure index (ABPI). Cases were selected from those who had ABPI 0.85 or less (ABPI ≤0.85) in either lower limb. Controls were selected from those ABPI score between 1.18 and 1.28 in both lower limbs. Only newly identified individuals with PAD were selected as cases. Controls were selected from the same geographical location and within the 5 year age group as cases.Results
The history of diabetes mellitus more than 10 years (OR 5.8, 95% CI 2.2–14.2), history of dyslipidemia for more than 10 years (OR 4.9, 95% CI 2.1–16.2), history of hypertension for more than 10 years (OR 3.8, 95% CI 1.8–12.7) and smoking (OR 2.9, 95% CI 1.2–6.9), elevated HsCRP (OR 3.7, 95% CI 1.2–12.0) and hyperhomocysteinemia (OR 3.0, 95% CI 1.1–8.1) were revealed as country specific significant risk factor of PAD.Conclusions
Diabetes mellitus, hypertension, dyslipidemia, smoking as well as elevated homocysteine and HsCRP found as risk factors of PAD. Longer the duration or higher level exposure to these risk factors has increased the risk of PAD. These findings emphasis the need for routine screening of PAD among patients with the identified risk factors.10.
Eva Santermans Emmanuel Robesyn Tapiwa Ganyani Bertrand Sudre Christel Faes Chantal Quinten Wim Van Bortel Tom Haber Thomas Kovac Frank Van Reeth Marco Testa Niel Hens Diamantis Plachouras 《PloS one》2016,11(1)