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91.
Effects of sex hormones and gender on attraction thresholds for volatile anal scent gland odors in ferrets 总被引:4,自引:0,他引:4
Body odors contribute to mate recognition and sexual partner preference in many mammals, including ferrets. We used a habituation/dishabituation procedure to test whether sex steroid hormones influence whether ferrets will approach and investigate different concentrations of volatile anal scent gland odors from male and female conspecifics. When tested with high concentrations of anal scent gland secretions in oil vehicle, gonadectomized male and female ferrets that received no sex steroids reliably discriminated anal scents from male and female conspecifics. This discrimination most likely reflects gender recognition rather than individual recognition because gonadectomized, sex steroid-treated ferrets discriminated between anal scents of males and females but not between anal scents of individual males or females. Treatment with either the estrogen receptor agonist, estradiol benzoate (EB), or the androgen receptor agonist, 5-alpha dihydrotestosterone proprionate (DHTP), increased investigation of low concentrations of anal scent by gonadectomized ferrets. These data suggest that ferrets could use anal scent gland secretions in mate recognition and that seasonal increases in circulating sex steroid hormones increase ferrets' responsiveness to low concentrations of these odors. 相似文献
92.
93.
Natural selection on the erythrocyte surface 总被引:6,自引:0,他引:6
Surface glycoproteins are principal receptors used by pathogens to invade target cells. It has been suggested that mammalian erythrocyte surface glycoproteins function as decoy receptors attracting pathogens to the anucleated erythrocyte and away from their target tissues. Glycophorin A (GYPA) is solely expressed on the erythrocyte surface where it is the most abundant sialoglycoprotein, although its function is unknown. The pathogen decoy hypothesis may be relevant here, as GYPA has been shown in vitro to bind numerous viruses and bacteria, which do not infect erythrocytes. However, it is also a receptor for erythrocyte invasion by the malarial parasite Plasmodium falciparum. Analyses of gypa sequence variation among six higher primates and within a human population show that there is a large excess of replacement (nonsynonymous) substitutions along each primate lineage (particularly on exons 2-4 encoding the extracellular glycosylated domain of GYPA) and a significant excess of polymorphisms in exon 2 (encoding the terminal portion of the extracellular domain) within humans. These two signatures suggest that there has been exceptionally strong positive selection on this receptor driving GYPA divergence during primate evolution and balancing selection maintaining allelic variation within human populations. The pathogen decoy hypothesis alone is adequate to explain both these signatures of between-species and within-species diversifying selection. This has implications for understanding the functions of erythrocyte surface components and their roles in health and disease. 相似文献
94.
Early Tertiary out-of-India dispersal of Crypteroniaceae: evidence from phylogeny and molecular dating 总被引:3,自引:0,他引:3
Conti E Eriksson T Schönenberger J Sytsma KJ Baum DA 《Evolution; international journal of organic evolution》2002,56(10):1931-1942
Abstract.— Pylogenetic analyses and molecular dating estimates based on chloroplast DNA sequences were used to establish the relationships of the southern and Southeast Asian Crypteroniaceae and elucidate their biogeographic history. Maximum parsimony and likelihood analyses of rbc L sequences suggested that Crypteroniaceae should be restricted to Crypteronia , Axinandra , and Dactylocladus and that Crypteroniaceae, so defined, are sister to a clade formed by three small African taxa (Oliniaceae, Penaeaceae, and Rhynchocalycaceae) and the monotypic Central and South American Alzateaceae. Three molecular dating approaches (maximum-likelihood under a molecular clock, Langley-Fitch, and penalized-likelihood) were used to infer the age of Crypteroniaceae using both paleobotanic and geologic calibrations. Comparisons among these three methods revealed significant lineage effects in rbc L sequences. Clock-independent dating estimates suggested that divergence of Crypteroniaceae from its African and South American relatives coincided with the breakup of Gondwana, and that India likely served as a "raft" transporting Crypteroniaceae to Asia, with later expansion to Southeast Asia. To our knowledge, Crypteroniaceae are the first plant group for which the out-of-India hypothesis is well corroborated by molecular-based estimates of divergence times. 相似文献
95.
Isolation of EST-derived microsatellite markers for genotyping the A and B genomes of wheat 总被引:39,自引:0,他引:39
Eujayl I Sorrells ME Baum M Wolters P Powell W 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(2-3):399-407
Genetic variation present in 64 durum wheat accessions was investigated by using three sources of microsatellite (SSR) markers:
EST-derived SSRs (EST-SSRs) and two sources of SSRs isolated from total genomic DNA. Out of 245 SSR primer pairs screened,
22 EST-SSRs and 20 genomic-derived SSRs were polymorphic and used for genotyping. The EST-SSR primers produced high quality
markers, but had the lowest level of polymorphism (25%) compared to the other two sources of genomic SSR markers (53%). The
42 SSR markers detected 189 polymorphic alleles with an average number of 4.5 alleles per locus. The coefficient of similarity
ranged from 0.28 to 0.70 and the estimates of similarity varied when different sources of SSR markers were used to genotype
the accessions. This study showed that EST-derived SSR markers developed in bread wheat are polymorphic in durum wheat when
assaying loci of the A and B genomes. A minumum of ten EST-SSRs generated a very low probability of identity (0.36×10−12) indicating that these SSRs have a very high discriminatory power. EST-SSR markers directly sample variation in transcribed
regions of the genome, which may enhance their value in marker-assisted selection, comparative genetic analysis and for exploiting
wheat genetic resources by providing a more-direct estimate of functional diversity.
Received: 19 December 2000 / Accepted: 17 April 2001 相似文献
96.
Volatile urinary odors from opposite sex conspecifics contribute to mate recognition in numerous mammalian species, including mice. We used a simple habituation/dishabituation testing procedure to ask whether the capacity to detect and investigate decreasing concentrations of volatile urinary odors is sexually differentiated in mice. Beginning 2 months after gonadectomy and in the absence of any sex steroid treatment, adult, sexually naive male and female CBA x C57Bl/6 F1 hybrid mice received two series of daily tests that involved the presentation of different dilutions of urine from C57Bl/6 males followed by urine from estrous females. Each test session began with three consecutive presentations of deionized water (10 microl on filter paper for 2 min, behind a mesh barrier which prevented direct physical access, in the home cage at 1-min intervals) followed by three presentations of one of five different dilutions of urine (a different dilution on each test day). Males and females showed equivalent, significant habituation/dishabituation responses (low investigation times for successive water presentations; increased investigation of the first urine stimulus, followed by a decline in successive urine investigation times) to both male and female urine/water dilutions of 1:1, 1:10, and 1:20. However, only female mice responded reliably to 1:40 and 1:80 dilutions of both types of urine, pointing to a sex dimorphism in the detection and/or processing of biologically relevant, volatile urinary odors by the main olfactory system. 相似文献
97.
98.
Mazarei M Puthoff DP Hart JK Rodermel SR Baum TJ 《Molecular plant-microbe interactions : MPMI》2002,15(6):577-586
99.
Ah,sweet mystery of death! Galectins and control of cell fate 总被引:9,自引:0,他引:9
Control of cell death is critical in eukaryotic development, immune system homeostasis, and control of tumorigenesis. The galectin family of lectins is implicated in all of these processes. Other families of molecules function as death receptors or death effectors, but galectins are uniquely capable of acting both extracellularly and intracellularly to control cell death. Extracellularly, galectins cross-link glycan ligands to transduce signals that lead directly to death or that influence other signals regulating cell fate. Intracellular expression of galectins can modulate other signals controlling cell viability. Individual galectins can act on multiple cell types, and multiple galectins can act on the same cell. Understanding how galectins regulate cell viability and function will broaden our knowledge of the roles of galectins in basic biological processes and facilitate development of therapeutic applications for galectins in autoimmunity, transplant-related disease, and cancer. 相似文献
100.
Beier M Baum M Rebscher H Mauritz R Wixmerten A Stähler CF Müller M Stähler PF 《Biochemical Society transactions》2002,30(2):78-82
Concepts and results are described for the use of a single, but extremely flexible, probing tool to address a wide variety of genomic questions. This is achieved by transforming genomic questions into a software file that is used as the design scheme for potentially any genomic assay in a microarray format. Microarray fabrication takes place in three-dimensional microchannel reaction carriers by in situ synthesis based on spatial light modulation. This set-up allows for maximum flexibility in design and realization of genomic assays. Flexibility is achieved at the molecular, genomic and assay levels. We have applied this technology to expression profiling and genotyping experiments. 相似文献