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221.
Bennett R Adams B French A Neggers Y Vincent JB 《Biological trace element research》2006,113(1):53-66
Chromium is generally believed to be an essential element and is often claimed to have value as a weight loss or muscle building
agent. Recent studies in humans and rats have failed to demonstrate effects on body composition, although recent studies with
pharmacological doses of the cation [Cr(III)3O(O2CCH2CH3)6(H2O)3]+ (or Cr3) (≤1 mg Cr/kg body mass) in rats have noted a trend toward body mass loss and fat mass loss. Thus, the effects of
large gavage doses of Cr3 (1–10 mg Cr/kg) on body mass, organ mass, food intake, and blood plasma variables (insulin, glucose,
leptin, cholesterol, and triglycerides) were examined over a 10-wk period using male Sprague-Dawley rats. No effects on body
composition were noted, although Cr3 administration lowered (p<0.05) plasma insulin, leptin, and triglycerides concentrations. As Cr3 is absorbed greater than 10-fold better than commercially
available nutritional supplements, the lack of an effect of the Cr(III) compound at these levels of administration clearly
indicates that Cr(III) supplements do not have an effect on body composition at any reasonable dosage. 相似文献
222.
Gül N Ozsoy N Osmanagaoglu O Selmanoğlu G Koçkaya EA 《Cell biochemistry and function》2006,24(6):541-546
Patulin is a mycotoxin that is produced by species of Penicillum, Aspergillus, and Byssochylamys molds that may grow on a variety of foods including fruit, grains and cheese. Patulin, at a dose of 0.1 mg kg(-1) bw day(-1) was administered orally to growing male rats aged 5-6 weeks for a period of 60 or 90 days. The dose of patulin used in the present study was based on estimated human exposure levels. At the end of these periods, the thymus glands of patulin-treated and control Wistar rats were removed and ultrastructural changes in capillary cells of the thymus of patulin-treated Wistar rats were determined by electron microscopy. The walls of thymus capillaries of the 60-day patulin-treated rat groups (P-60) exhibited degeneration observable in electron microscopic sections. For example, loss of cytoplasm and mitochondrial cristae of cells, swollen endothelial cells, increased thickness of the basement membrane, closed lumen of capillaries, accumulation of fibrous material at the periphery of the capillaries and nuclear anomalies were seen in these sections. Such degeneration and changes were also observed in sections of capillaries of the 90-day patulin-treated rat groups (P-90). The levels of degeneration of endothelial cell nucleus of P-90 were greater than those of P-60. This study demonstrated the ultrastructural degeneration of thymus capillary cells of patulin-treated rats. The results obtained from this study may provide a guide to research dealing with the toxic effects of patulin on tissue and organ ultrastructure. 相似文献
223.
In the current study, the improved oral bioavailability of a synthetic astaxanthin derivative (CardaxTM; disodium disuccinate astaxanthin) was utilized to evaluate its potential effects as a cardioprotective agent after 7-day
subchronic oral administration as a feed supplement to Sprague-Dawley rats. Animals received one of two concentrations of
CardaxTM in feed (0.1 and 0.4%; ∼125 and 500 mg/kg/day, respectively) or control feed without drug for 7 days prior to the infarct
study carried out on day 8. Thirty minutes of occlusion of the left anterior descending (LAD) coronary artery was followed
by 2 h of reperfusion prior to sacrifice, a regimen which resulted in a mean infarct size (IS) as a percentage (%) of the
area at risk (AAR; IS/AAR,%) of 61 ± 1.8%. The AAR was quantified by Patent blue dye injection, and IS was determined by triphenyltetrazolium
chloride (TTC) staining. CardaxTM at 0.1 and 0.4% in feed for 7 days resulted in a significant mean reduction in IS/AAR,% to 45 ± 2.0% (26% salvage) and 39
± 1.5% (36% salvage), respectively. Myocardial levels of free astaxanthin achieved after 7-day supplementation at each of
the two concentrations (400 ± 65 nM and 1634 ± 90 nM, respectively) demonstrated excellent solid-tissue target organ loading
after oral supplementation. Parallel trends in reduction of plasma levels of multiple lipid peroxidation products with disodium
disuccinate astaxanthin supplementation were observed, consistent with the documented in vitro antioxidant mechanism of action. These results extend the potential utility of this compound for cardioprotection to the
elective human cardiovascular patient population, for which 7-day oral pre-treatment (as with statins) provides significant
reductions in induced periprocedural infarct size. 相似文献
224.
225.
The present study has aimed to verify the influence of calcineurin and mTOR pathways in skeletal muscle longitudinal growth
induced by stretching. Male Wistar rats were treated with cyclosporin-A or rapamycin for 10 days. To promote muscle stretching,
casts were positioned so as completely to dorsiflex the plantar-flexor muscles at the ankle in one hind limb during the last
4 days of treatment with either cyclosporin-A or rapamycin. Thereafter, we determined soleus length, weight, protein content,
and phenotype. In addition, NFATc1, Raptor, S6K1, 4E-BP1, iNOS, and nNOS gene expression in the soleus were determined by
real-time polymerase chain reaction. Soleus length, weight, and protein content were significantly reduced by rapamycin treatment
in animals submitted to stretching (P<0.05). In contrast, cyclosporin-A treatment did not alter these parameters. In all cyclosporin-A treated groups, there was
a significant reduction in NFATc1 expression (P<0.001). Similarly, a significant reduction was noted in Raptor (P<0.001) and S6K1 (P<0.01) expression in all rapamycin-treated groups. No alteration was observed in 4E-BP1 gene expression among rapamycin-treated
groups. Stretching increased gene expression of both NOS isoforms in skeletal muscle. Rapamycin treatment did not interfere
with NOS gene expression (P<0.05). Cyclosporin-A treatment did not impair muscle growth induced by stretching but instead caused a marked slow-to-fast
fiber shift in the soleus; this was attenuated by stretching. The data presented herein indicate that mTOR pathway is involved
in skeletal muscle longitudinal growth.
We gratefully acknowledge the financial support given by FAPESP. 相似文献
226.
The goal of this study was to determine the acute effects of permanent denervation on the length density of the capillary
network in rat slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles and the effect of short-lasting reinnervation
in slow muscle only. Denervation was performed by cutting the sciatic nerve. Both muscles were excised 2 weeks later. Reinnervation
was studied 4 weeks after nerve crush in SOL muscle only. Capillaries and muscle fibres were visualised by triple immunofluorescent
staining with antibodies against CD31 and laminin and with fluorescein-labelled Griffonia (Bandeira) simplicifolia lectin. A recently developed stereological approach allowing the estimation of the length of capillaries adjacent to each
individual fibre (Lcap/Lfib) was employed. Three-dimensional virtual test grids were applied to stacks of optical images captured with a confocal microscope
and their intersections with capillaries and muscle fibres were counted. Interrelationships among capillaries and muscle fibres
were demonstrated with maximum intensity projection of the acquired stacks of optical images. The course of capillaries in
EDL seemed to be parallel to the fibre axes, whereas in SOL, their preferential direction deviated from the fibre axes and
formed more cross-connections among neighbouring capillaries. Lcap/Lfib was clearly reduced in denervated SOL but remained unchanged in EDL, although the muscle fibres significantly atrophied in
both muscle types. When soleus muscle was reinnervated, capillary length per unit fibre length was completely restored. The
physiological background for the different responses of the capillary network in slow and fast muscle is discussed.
This study was supported by the Slovenian Research Agency and the Ministry of Education, Youth and Sport of the Czech Republic
(KONTAKT grant no. 19/2005). 相似文献
227.
228.
Cotton rats (Sigmodon hispidus, inbred strain COTTON/NIco) have been shown to be a good animal model to investigate measles virus (MV) immune suppression and to assess alternative vaccine candidates against MV infection. Here we demonstrate that cotton rats develop a bronchusassociated and interstitial pneumonia with necrotic lesions after intranasal infection resembling findings from fatal cases of human MV pneumonia. In the absence of superinfection restitutio ad integrum is observed and overcoming of lung infection correlates with the development of MV specific neutralizing antibodies. 相似文献
229.
Between 1988 and 1997, 72 mouse colonies and 38 rat colonies were examined for the presence of bacteria parasite infections. Among mouse and rat bacteria, high positive rates were observed with Proteus species (sp.), Pasteurella pneumotropica, Mycoplasma sp. and Pseudomonas aeruginosa. Concerning murine colonies, parasites frequently detected were Tritrichomonas sp., Syphacia sp., Aspiculuris tetraptera, Entamoeba muris, Spironucleus muris, Myobia musculi, Chilomastix sp. and Myocoptes musculinus. In rats, high rates were obtained with Syphacia sp., Tritrichomonas sp., Spironucleus muris, Entamoeba muris and Chilomastix sp. During the first part of the last decade, some agents such as Clostridium piliforme, Citrobacter sp., Mycoplasma sp., Pseudomonas aeruginosa, Myobia musculi, Radfordia ensifera, Spironucleus muris and Giardia muris were often found among rodents, and most of them were still present in 1997. At the time of our study, results point out that some agents are still persistent, even increasing during the same period. It is particularly the case for parasites such as Entamoeba muris and the oxyurids, but also for bacteria like Proteus sp. and Klebsiella pneumoniae. We can thus conclude that only very limited success has been achieved in preventing microbial and parasitic infections in mice and rats colonies. 相似文献
230.
Miller RR 《Behavioural processes》2012,90(1):81-3; discussion 87-8
Gallistel (2012) asserts that animals use rationalistic reasoning (i.e., information theory and Bayesian inference) to make decisions that underlie select extinction phenomena. Rational processes are presumed to lead to evolutionarily optimal behavior. Thus, Gallistel's model is a type of optimality theory. But optimality theory is only a theory, a theory about an ideal organism, and its predictions frequently deviate appreciably from observed behavior of animals in the laboratory and the real world. That is, behavior of animals is often far from optimal, as is evident in many behavioral phenomena. Hence, appeals to optimality theory to explain, rather than illuminate, actual behavior are misguided. 相似文献