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71.
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The ability of juvenile turbot, Scophthalmus maximus (L.), to elongate and desaturate various polyunsaturated fatty acids (PUFA) was examined in relation to their lipid composition. Triacylglycerols were the most abundant lipid class present in the fish and phosphatidylcholine was the predominant phospholipid. In all lipid classes examined the levels of (n-3) PUFA exceeded that of (n-6) PUFA. 18C PUFA were minor components in comparison with 20:5(n-3) and 22:6(n-3). 20:4(n-6) was present in highest concentration in phosphatidylinositol in which it accounted for 16.9% of the fatty acids. When the fish were injected with either 14C-labelled 18:2(n-6), 18:3(n-3), 20:4(n-6), 20:5(n-3) or 22:6(n-3) the highest percentage recovery of radioactivity (69%) in body lipid was observed with 22:6(n-3). With all labelled substrates free fatty acids contained only a small proportion of the total recovered radioactivity whereas triacylglycerols were highly labelled. Phosphatidylcholine/sphingomyelin was the most highly labelled polar lipid fraction. With 14C-20:4(n-6) as injected substrate, 23.2% of the radioactivity recovered in total lipid was present in phosphatidylinositol in comparison with less than 6% with the other substrates. Only small proportions of radioactivity from 14C-18:2(n-6) and 14C-18:3(n-3) were recovered in the 20 and 22C fatty acids of triacylglycerols and total polar lipid. With 14C-20:5(n-3) as substrate, 27 and 33% of the total radioactivity recovered in the fatty acids of triacylglycerols and polar lipids respectively was present in 22C fatty acids. The corresponding values for l4C-20:4(n-6) as substrate were 19 and 18%. The results confirm the limited capacity of turbot to convert 18C PUFA to longer chain PUFA but demonstrate their ability to synthesize 22C PUFA from 20C PUFA. They also suggest a small but specific requirement for 20:4(n-6). 相似文献
74.
Leticia Morales-Ledesma Rosa Linares Gabriela Rosas Carolina Morán Roberto Chavira Mario Cárdenas Roberto Domínguez 《Reproductive biology and endocrinology : RB&E》2010,8(1):99
The present study tested the hypothesis that if polycystic ovary syndrome (PCOS) results from activating the noradrenergic
outflow to the ovary, unilaterally sectioning the superior ovarian nerve (SON) will result in ovulation by the denervated
ovary, and the restoration of progesterone (P4), testosterone (T) and estradiol (E2) normal serum level. A single 2 mg dose
of estradiol valerate (EV) to adult rats results in the development of a syndrome similar to the human PCOS. Ten-day old rats
were injected with EV or vehicle solution (Vh) and were submitted to sham surgery, unilateral or bilateral sectioning of the
SON at 24-days of age. The animals were sacrificed at 90 to 92 days of age, when they presented vaginal estrus preceded by
a pro-estrus smear. In EV-treated animals, unilateral sectioning of the SON restored ovulation by the innervated ovary and
unilateral or bilateral sectioning of the SON normalized testosterone and estradiol levels. These results suggest that aside
from an increase in ovarian noradrenergic tone in the ovaries, in the pathogenesis of the PCOS participate other neural influences
arriving to the ovaries via the SON, regulating spontaneous ovulation. Changes in P4, T and E2 serum levels induced by EV
treatment seem to be controlled by neural signals arising from the abdominal wall and other signals arriving to the ovaries
through the SON, and presents asymmetry. 相似文献
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Ziello C Sparks TH Estrella N Belmonte J Bergmann KC Bucher E Brighetti MA Damialis A Detandt M Galán C Gehrig R Grewling L Gutiérrez Bustillo AM Hallsdóttir M Kockhans-Bieda MC De Linares C Myszkowska D Pàldy A Sánchez A Smith M Thibaudon M Travaglini A Uruska A Valencia-Barrera RM Vokou D Wachter R de Weger LA Menzel A 《PloS one》2012,7(4):e34076
A progressive global increase in the burden of allergic diseases has affected the industrialized world over the last half century and has been reported in the literature. The clinical evidence reveals a general increase in both incidence and prevalence of respiratory diseases, such as allergic rhinitis (common hay fever) and asthma. Such phenomena may be related not only to air pollution and changes in lifestyle, but also to an actual increase in airborne quantities of allergenic pollen. Experimental enhancements of carbon dioxide (CO[Formula: see text]) have demonstrated changes in pollen amount and allergenicity, but this has rarely been shown in the wider environment. The present analysis of a continental-scale pollen data set reveals an increasing trend in the yearly amount of airborne pollen for many taxa in Europe, which is more pronounced in urban than semi-rural/rural areas. Climate change may contribute to these changes, however increased temperatures do not appear to be a major influencing factor. Instead, we suggest the anthropogenic rise of atmospheric CO[Formula: see text] levels may be influential. 相似文献
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78.
Limnology - Benthic macroinvertebrate assemblages are used to assess anthropogenic stressors and pressures globally—although considerable spatial and temporal variability in those assemblages... 相似文献
79.
This paper analyses the relationship between extreme temperatures and mortality among persons aged 45–64 years. Daily mortality in Madrid was analysed by sex and cause, from January 1986 to December 1997. Quantitative analyses were performed using generalised additive models, with other covariables, such as influenza, air pollution and seasonality, included as controls. Our results showed that impact on mortality was limited for temperatures ranging from the 5th to the 95th percentiles, and increased sharply thereafter. During the summer period, the effect of heat was detected solely among males in the target age group, with an attributable risk (AR) of 13.3% for circulatory causes. Similarly, NO2 concentrations registered the main statistically significant associations in females, with an AR of 15% when circulatory causes were considered. During winter, the impact of cold was exclusively observed among females having an AR of 7.7%. The magnitude of the AR indicates that the impact of extreme temperature is by no means negligible.Julio Díaz is adviser to the Madrid Autonomous University General Foundation, on behalf of the Department of Education for Sustainable Development, Madrid City Council, Madrid, Spain 相似文献
80.
Reyes-Toso CF Rebagliati IR Ricci CR Linares LM Albornoz LE Cardinali DP Zaninovich A 《Amino acids》2006,31(3):299-302
Summary. The objective of this study was to examine the in vivo effect of melatonin on rat mitochondrial liver respiration. Two experiments were performed: For experiment 1, adult male
rats received melatonin in the drinking water (16 or 50 μg/ml) or vehicle during 45 days. For experiment 2, rats received
melatonin in the drinking water (50 μg/ml) for 45 days, or the same amount for 30 days followed by a 15 day-withdrawal period.
At sacrifice, a liver mitochondrial fraction was prepared and oxygen consumption was measured polarographically in the presence
of excess concentration of DL-3-β-hydroxybutyrate or L-succinate. Melatonin treatment decreased Krebs’ cycle substrate-induced
respiration significantly at both examined doses. The stimulation of mitochondrial respiration caused by excess concentration
of substrate recovered after melatonin withdrawal. Basal state 4 respiration was not modified by melatonin. Melatonin, by
curtailing overstimulation of cellular respiration caused by excess Krebs’ cycle substrates, can protect the mitochondria
from oxidative damage. 相似文献