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161.
162.
Nitric oxide and changes of iron metabolism in exercise 总被引:12,自引:0,他引:12
Qian ZM 《Biological reviews of the Cambridge Philosophical Society》2002,77(4):529-536
Accumulated data imply that exercise itself might not lead to a true iron deficiency or 'sport anaemia' in a healthy athlete who has adequate iron intake. The higher prevalence of iron deficiency anaemia in younger female athletes might be not due to exercise itself, but probably results from dietary choices, inadequate iron intake and menstruation. These factors can also induce iron deficiency or anaemia in the general population. However, exercise does affect iron metabolism, leading to low or sub-optimal iron status. The underlying mechanism is unknown. In this review, recent advances in the study of the effect of exercise on iron metabolism and nitric oxide, and the relationship between nitric oxide and iron status in exercise are discussed. A hypothesis that increased production of nitric oxide might contribute to sub-optimal iron status in exercise is proposed. 相似文献
163.
Setchell Joanna M. Lee Phyllis C. Wickings E. Jean Dixson Alan F. 《International journal of primatology》2002,23(1):51-68
We report on 14 years of reproductive data for semifree-ranging mandrills (Mandrillus sphinx) in Gabon, and we explore relationships between female rank, age and parity, and reproductive strategies. Most births (61% of 132) occurred during the wet season in Gabon, between January and March. Female rank and parity were unrelated to the timing of parturition. Gestation lengths average 175 days (SE = ±1 day; N = 61) and were similar irrespective of female rank, parity, or sex of offspring. Birth sex ratio did not differ significantly from unity (52% male), and was unrelated to maternal rank or parity. Stillbirths and neonatal mortality tended to be more common among lower-ranking females than among either mid-ranking or dominant females. Median age at first birth is 4.71 years, at a median body mass of 7.6 kg, ca 5 years before females attain their adult body mass (median 12 kg). Age at first reproduction is significantly correlated with dominance rank, with dominant females giving birth on average 1.3 years earlier than lower-ranking females do. Interbirth intervals (IBI) average 405 days (range 184–1159 days, N = 103), and are independent of the sex of the offspring. Infant death within 6 months shortened IBI to 305 days. Increasing age and parity are also associated with short IBI, as is higher rank. Maternal rank and parity appear to influence reproductive success in female mandrills, but there is no apparent differential maternal investment by sex. 相似文献
164.
Sexual attractiveness of unengorged, semiengorged and fully engorged females of both field and laboratory populations of Ixodes ricinus was studied under laboratory conditions by means of a computerised video tracking system. A male and a female were allowed
to walk freely in a glass arena during 1 h and their behavioural interactions were observed. Obtained results revealed that
the feeding status of I. ricinus females affects their sexual attractiveness. The highest attractiveness was observed in engorged females, the lowest in unengorged
females of the field population. Copulation occurred in all experimental groups with the highest frequency observed in the
unengorged virgin laboratory females. Despite engorged females being highly attractive for males on distance, the frequency
of copulation was low. Differences between field and laboratory populations were found in both behavioural parameters and
frequency of copulation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
165.
Yoichi Sakai Kenji Karino Yasuhiro Nakashima Tetsuo Kuwamura 《Journal of Ethology》2002,20(2):101-105
To examine how a change in an individual's social status could influence its behavioural sex, we conducted male "removal-and-return"
experiments in the polygynous wrasse, Halichoeres melanurus. This coral-reef fish is a protogynous hermaphrodite: the largest female (LF) living in a male's territory typically completes
functional sex change within 2–3 weeks after the male's disappearance. In this experiment we removed males from their territories
just prior to spawning time, about 1 h before sunset. In 12 of 30 trials, the resident LF spawned in the male role with smaller
females, 21–98 min after male removal. Previous research suggests the LF should readily adopt male sexual behaviour to retain
smaller females as future mates. However, the LFs of smaller body size were less likely to immediately perform male-role behaviour.
This could be related to females' preference for larger mates: smaller LFs would be less likely to be chosen by other females,
even if they could complete sex change and defend a territory. When a male was returned immediately after an occurrence of
female–female spawning, the LF subsequently spawned in the female role with the returned male (6 of 12 trials). It could be
adaptive for the LFs to accept a larger male as a mate rather than to fight against it. Thus, behavioural sex is reversible
in H. melanurus, changing rapidly with social status.
Electronic Publication 相似文献
166.
Elhaïmeur F Courderot-Masuyer C Nicod L Guyon C Richert L Berthelot A 《Molecular and cellular biochemistry》2002,237(1-2):77-83
The effects of a vitamin C supplemented diet on blood pressure, body and liver weights, liver antioxidant status, iron and copper levels were investigated in DOCA-salt treated and untreated Sprague-Dawley (SD) male rats after 8 weeks of treatment. Vitamin C supplementation had no effect on blood pressure in SD rats but induced a significant decrease in blood pressure in DOCA-salt treated rats, the decrease being more efficient at 50 mg/kg of vitamin C than at 500 mg/kg. Hepatic lipid peroxidation and iron levels were significantly increased in DOCA-salt hypertensive rats whereas total hepatic antioxidant capacity (HAC), glutathione peroxidase (GSH-Px) and catalase (CAT) activities were decreased. Vitamin C supplementation did not affect the overall antioxidant defences of control SD rat livers. In contrast, vitamin C supplementation accentuated the DOCA-salt induced accumulation of liver iron and lipid peroxidation. This occurred without any notable aggravation in the antioxidant deficiency of vitamin C supplemented DOCA-salt treated rat livers. Our data suggest that DOCA-salt treatment induces an accumulation of iron in rat livers which is responsible for the prooxidant effect of vitamin C. The normalization of blood pressure in DOCA-salt treated rats by vitamin C supplementation appears thus independent from liver antioxidant status. 相似文献
167.
In the absence of longitudinal data, the current presence and severity of disease can be measured for a sample of individuals to investigate factors related to disease incidence and progression. In this article, Bayesian discrete-time stochastic models are developed for inference from cross-sectional data consisting of the age at first diagnosis, the current presence of disease, and one or more surrogates of disease severity. Semiparametric models are used for the age-specific hazards of onset and diagnosis, and a normal underlying variable approach is proposed for modeling of changes with latency time in disease severity. The model accommodates multiple surrogates of disease severity having different measurement scales and heterogeneity among individuals in disease progression. A Markov chain Monte Carlo algorithm is described for posterior computation, and the methods are applied to data from a study of uterine leiomyoma. 相似文献
168.
This paper describes changes in leaf water status and in stem, petiole and leaf blade hydraulics preceding leaf senescence and shedding in Castanea sativa L. (chestnut). Measurements of maximum diurnal leaf conductance to water vapour (gL), minimum water potential (L), hydraulic conductance per unit leaf surface area of stems (KSL), petioles (KPL) and leaf blades (KLL) and number of functional conduits and inside diameter distribution were performed in June, September and October 1999. In September, still green leaves had undergone some dehydration as indicated by decreased gL (by 75 %) and L with respect to June. In the same time, KSL decreased by 88 %, while KPL and KLL decreased by 50 % and 20 % of the conduits of stems and 10 % of the petioles (all belonging to the widest diameter range) were no longer functioning, causing a decrease in the theoretical flow by 82 % in stems and 27 % in petioles. Stem xylem blockage was apparently due to tyloses growing into conduits. We advance the hypothesis that the entire process of leaf shedding and winter rest may be initiated by extensive stem embolism occurring during the summer. 相似文献
169.
Tanzer MM Arst HN Skalchunes AR Coffin M Darveaux BA Heiniger RW Shuster JR 《Functional & integrative genomics》2003,3(4):160-170
We describe a method for gene function discovery and chemical mode-of-action analysis via nutrient utilization using a high throughput Nutritional Profiling platform suitable for filamentous microorganisms. We have optimized the growth conditions for each fungal species to produce reproducible optical density growth measurements in microtiter plates. We validated the Nutritional Profiling platform using a nitrogen source utilization assay to analyze 21 Aspergillus nidulans strains with mutations in the master nitrogen regulatory gene, areA. Analysis of these data accurately reproduced expected results and provided new data to demonstrate that this platform is suitable for fine level phenotyping of filamentous fungi. Next, we analyzed the differential responses of two fungal species to a glutamine synthetase inhibitor, illustrating chemical mode-of-action analysis. Finally, a comparative phenotypic study was performed to characterize carbon catabolite repression in four fungal species using a carbon source utilization assay. The results demonstrate differentiation between two Aspergillus species and two diverse plant pathogens and provide a wealth of new data on fungal nutrient utilization. Thus, these assays can be used for gene function and chemical mode-of-action analysis at the whole organism level as well as interspecies comparisons in a variety of filamentous fungi. Additionally, because uniform distribution of growth within wells is maintained, comparisons between yeast and filamentous forms of a single organism can be performed.Electronic Supplementary Material Supplementary material is available in the online version of this article at
The revised version of the PDF file was published online in January 2004. The figures are now in color.An erratum to this article can be found at 相似文献
170.
We examined the effect of predation risk on female association patterns in the live-bearing sailfin molly (Poecilia latipinna). We tested two classes of females, with and without the risk of predation by a green sunfish (Lepomis cyanellus): (1) postpartum females (maintained with males until visibly gravid, then isolated and tested within 24–48 h of dropping a brood); and (2) non-postpartum females (different females, isolated from males for >50 days). When there was no apparent risk of predation, postpartum females showed a significant preference for large over small males, whereas non-postpartum females showed no size preference at all. When there was an apparent risk of predation, postpartum females maintained their preference for larger males and non-postpartum females continued to show no preference for large or small males. These results suggest that reproductive status (receptivity) plays a greater role in mate preference than predation risk. For postpartum females, the cost of not choosing a preferred mate may outweigh the potential cost of predation. Non-postpartum females either do not benefit from mating or are being indecisive about mating and thus are less likely to be choosy whether or not a predator is present.Communicated by I. Schlupp 相似文献