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141.
142.
Involvement of intracellular calcium stores in Giardia lamblia induced diarrhoea in mice 总被引:1,自引:0,他引:1
Sushumma Gorowara Nirmal K. Ganguly Ramesh C. Mahajan Brij N.S. Walia 《FEMS microbiology letters》1994,120(3):231-236
Abstract The transmucosal fluxes of Na+ and Cl− were studied in Giardia lamblia -infected mice in the presence of absence of dantrolene (1-(5( p -nitrophenyl)furfurilidene-amino) hydantoin sodiumhydrate ). There was net secretion of Na+ and Cl− in infected animals, while in control animals there was net absorption of these ions. The addition of dantrolene resulted in significant net increase in absorption of Na+ and Cl− in control and experimental groups. Further, mouse intestinal epithelial cells were labelled with [32 P]Pi and then treated with G. lamblia trophozoites and their excretory secretory products separately. The optimum time for inositol triphosphate formation was 15 min in control enterocytes as well as in treated enterocytes. A plateau was formed at higher concentrations. Since raised inositol triphosphate levels mobilize Ca2+ from intracellular stores and dantrolene traps Ca2+ within intracellular calcium stores, the present study thus suggests that intracellular calcium stores are involved in G. lamblia -induced diarrhoea in mice. 相似文献
143.
Vitamin C deficiency in Channa punctatus Bloch 总被引:1,自引:0,他引:1
The results of a series of experiments on Channa punctatus previously conditioned to a complete synthetic diet and later fed vitamin C deficient diet for 210 days followed by 30 days of recovery with fortified vitamin C ration are reported. The survival, growth, morphological abnormalities and biochemical changes in tissue ascorbic acid and cholesterol levels were studied.
Deficiency of vitamin C resulted in a mortality of up to 25% and retarded growth accompanied by anorexia and loss of weight. Marked skeletal abnormalities, viz. , lordosis, scoliosis and degenerative changes in the thoracic vertebrae were revealed by X-ray studies. Biochemical investigations showed a significant decrease in blood and kidney ascorbic acid levels within a month of feeding the deficient diet. A prolonged deficiency beyond 150 days resulted in a rapid rise in the cholesterol content of the liver. These biochemical changes were reversed when vitamin C was added to the ration. 相似文献
Deficiency of vitamin C resulted in a mortality of up to 25% and retarded growth accompanied by anorexia and loss of weight. Marked skeletal abnormalities, viz. , lordosis, scoliosis and degenerative changes in the thoracic vertebrae were revealed by X-ray studies. Biochemical investigations showed a significant decrease in blood and kidney ascorbic acid levels within a month of feeding the deficient diet. A prolonged deficiency beyond 150 days resulted in a rapid rise in the cholesterol content of the liver. These biochemical changes were reversed when vitamin C was added to the ration. 相似文献
144.
S D Mahajan R Aalinkeel S Singh P Shah N Gupta N Kochupillai 《Hormones et métabolisme》2005,37(10):633-640
Data on the effect of maternal malnutrition and/or anemia on thyroid hormone regulation in human fetuses are scarce, and would be of great importance in examining the relevance of Barker's hypothesis, which proposes adaptation of fetuses to undernutrition leading to permanent metabolic and endocrine changes that form the basis of adult diseases. To examine the quantitative variations in thyroid hormone profile of neonates born to malnourished and/or anemic mothers, we quantitated the T3, T4, rT3 and TSH levels in cord blood of neonates and maternal blood of their corresponding mothers that are malnourished and/or anemic. Further, we classified neonates born to each of these groups of mothers into Small for Gestational Age (SGA) or Appropriate for Gestational Age (AGA) based on the intrauterine growth curve for our population, and examined the thyroid hormone profile in these neonates. Our results show that firstly, the effects of malnutrition or anemia on thyroid hormone profile are distinct, secondly, significantly higher levels of cord blood T4 and correspondingly lower levels of T3 and rT3 are observed in the neonates born to anemic and malnourished mothers and thirdly, decreases in cord blood T3 levels were observed in Small for Gestational Age neonates born to anemic mothers. These observations lead us to speculate that alterations in the pituitary-thyroid function result in beneficial adaptations to the hostile intrauterine environment in malnutrition related growth retardation and anemia. 相似文献
145.
Clines, clusters, and the effect of study design on the inference of human population structure
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Previously, we observed that without using prior information about individual sampling locations, a clustering algorithm applied to multilocus genotypes from worldwide human populations produced genetic clusters largely coincident with major geographic regions. It has been argued, however, that the degree of clustering is diminished by use of samples with greater uniformity in geographic distribution, and that the clusters we identified were a consequence of uneven sampling along genetic clines. Expanding our earlier dataset from 377 to 993 markers, we systematically examine the influence of several study design variables—sample size, number of loci, number of clusters, assumptions about correlations in allele frequencies across populations, and the geographic dispersion of the sample—on the “clusteredness” of individuals. With all other variables held constant, geographic dispersion is seen to have comparatively little effect on the degree of clustering. Examination of the relationship between genetic and geographic distance supports a view in which the clusters arise not as an artifact of the sampling scheme, but from small discontinuous jumps in genetic distance for most population pairs on opposite sides of geographic barriers, in comparison with genetic distance for pairs on the same side. Thus, analysis of the 993-locus dataset corroborates our earlier results: if enough markers are used with a sufficiently large worldwide sample, individuals can be partitioned into genetic clusters that match major geographic subdivisions of the globe, with some individuals from intermediate geographic locations having mixed membership in the clusters that correspond to neighboring regions. 相似文献
146.
Whereas alpha-peptides are rapidly degraded in vivo and in vitro by a multitude of peptidases, substrates constructed entirely of or incorporating homologated alpha-amino acid (i.e., beta-amino acid) units exhibit a superior stability profile. Efforts made so far to proteolytically hydrolyze a beta-beta peptide bond have not proved fruitful; a study aimed at breaching this proteolytic stability is discussed here. A series of such bonds have been designed with side-chain groups similar in relative positions (constitution) and three-dimensional arrangements (configuration) as found about alpha-peptidic amide bonds. Increasing the prospect for degradation would permit the tuning of beta-peptide stability; here, however, no cleavage was observed (1, 2, 4-6, Table 1). Peptides comprised of alpha- and beta-amino acids (mixed alpha,beta-peptides, 8-11) are expected to benefit from both recognition by a natural receptor and a high level of proteolytic stability, ideal characteristics of pharmacologically active compounds. Beta3-peptides containing alpha-amino acid moieties at the N-terminus are degraded, albeit slowly, by several peptidases. Of particular interest is the ability of pronase to cleave an alpha-beta peptide bond, namely that of alphaAla-beta3 hAla. Significantly, successful hydrolysis is independent of the configuration of the beta-amino acid. Some of the alpha,beta-peptides discussed here are being investigated for their binding affinities to class I MHC proteins. The computer-programming steps required to prepare alpha,beta-peptides on an automated peptide synthesizer are presented. 相似文献
147.
McCabe SL Pelosi DM Tetreault M Miri A Nguitragool W Kovithvathanaphong P Mahajan R Zimmerman AL 《The Journal of general physiology》2004,123(5):521-531
Rod vision begins when 11-cis-retinal absorbs a photon and isomerizes to all-trans-retinal (ATR) within the photopigment, rhodopsin. Photoactivated rhodopsin triggers an enzyme cascade that lowers the concentration of cGMP, thereby closing cyclic nucleotide-gated (CNG) ion channels. After isomerization, ATR dissociates from rhodopsin, and after a bright light, this release is expected to produce a large surge of ATR near the CNG channels. Using excised patches from Xenopus oocytes, we recently showed that ATR shuts down cloned rod CNG channels, and that this inhibition occurs in the nanomolar range (aqueous concentration) at near-physiological concentrations of cGMP. Here we further characterize the ATR effect and present mechanistic information. ATR was found to decrease the apparent cGMP affinity, as well as the maximum current at saturating cGMP. When ATR was applied to outside-out patches, inhibition was much slower and less effective than when it was applied to inside-out patches, suggesting that ATR requires access to the intracellular surface of the channel or membrane. The apparent ATR affinity and maximal inhibition of heteromeric (CNGA1/CNGB1) channels was similar to that of homomeric (CNGA1) channels. Single-channel and multichannel data suggest that channel inhibition by ATR is reversible. Inhibition by ATR was not voltage dependent, and the form of its dose-response relation suggested multiple ATR molecules interacting per channel. Modeling of the data obtained with cAMP and cGMP suggests that ATR acts by interfering with the allosteric opening transition of the channel and that it prefers closed, unliganded channels. It remains to be determined whether ATR acts directly on the channel protein or instead alters channel-bilayer interactions. 相似文献
148.
Novel quinazolines, having interesting antibacterial activity have been prepared, characterized and tested against a panel of susceptible and resistant Gram positive and Gram negative organisms. 相似文献
149.
150.
A systematic approach through computer assisted design to identify novel quinazolines having anxiolytic and GABAergic activity has been reported. 相似文献