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111.
An increase in gear ratio of the limb extensor muscles during joint extension has been suggested to be a mechanism that facilitates optimal power production by skeletal muscles. The objectives of this study were to: (1) measure gear ratios at the wrist, elbow, shoulder, ankle, knee, and hip joints of jumping dogs, (2) compute the work performed by each of these joints, and (3) measure muscle shortening velocity for a joint exhibiting an increasing gear ratio during joint extension. The gear ratio out-lever was computed by dividing the ground reaction force (GRF) moment by the GRF, whereas the in-lever was directly measured as the perpendicular distance from the joint center to the line of action of the extensor muscle. In addition, changes in fascicle length were measured from the vastus lateralis muscle using sonomicrometry. Of the joints examined, only the gear ratios at the shoulder and knee joints increased during jumping in a manner that could facilitate peak power production of actively shortening muscles. The vastus lateralis was found to shorten at an average velocity of 3.20 muscle lengths per second. This is similar to estimates of shortening velocity that produce peak muscular power in mammals the size of dogs. Additionally, the knee extensors were found to produce a large proportion (26.6%) of the positive external work of the limbs. These observations suggest that dynamic gearing in jumping dogs may allow the extensor muscles of the knee joint to shorten in a way that maximizes their power production. 相似文献
112.
Genetic association of the R620W polymorphism of protein tyrosine phosphatase PTPN22 with human SLE 总被引:17,自引:0,他引:17 下载免费PDF全文
Kyogoku C Langefeld CD Ortmann WA Lee A Selby S Carlton VE Chang M Ramos P Baechler EC Batliwalla FM Novitzke J Williams AH Gillett C Rodine P Graham RR Ardlie KG Gaffney PM Moser KL Petri M Begovich AB Gregersen PK Behrens TW 《American journal of human genetics》2004,75(3):504-507
We genotyped 525 independent North American white individuals with systemic lupus erythematosus (SLE) for the PTPN22 R620W polymorphism and compared the results with data generated from 1,961 white control individuals. The R620W SNP was associated with SLE (genotypic P=.00009), with estimated minor (T) allele frequencies of 12.67% in SLE cases and 8.64% in controls. A single copy of the T allele (W620) increases risk of SLE (odds ratio [OR]=1.37; 95% confidence interval [CI] 1.07-1.75), and two copies of the allele more than double this risk (OR=4.37; 95% CI 1.98-9.65). Together with recent evidence showing association of this SNP with type 1 diabetes and rheumatoid arthritis, these data provide compelling evidence that PTPN22 plays a fundamental role in regulating the immune system and the development of autoimmunity. 相似文献
113.
Small intestinal morphometric and biomechanical changes during physiological growth in rats 总被引:5,自引:0,他引:5
Changes in small intestinal geometry, residual strain and stress-strain properties during physiological growth were studied in rats ranging from 1 to 32 weeks of age. Small intestinal mass and dimensions increased many-fold with age, e.g. the weight per unit length increased five-fold with age and the wall cross-sectional area increased four-fold. The opening angle of duodenum obtained at zero-stress state was approximately 220 degrees and 290 degrees during the first and second week after birth and decreased to 170 degrees at other ages (p < 0.005). The opening angle of ileum ranged between 120 degrees and 150 degrees . The residual strain of duodenum at the mucosal surface did not vary with age (p > 0.05) whereas the residual strain of ileum at the mucosal surface decreased with age (p < 0.001). The circumferential and longitudinal stress-strain curves fitted well to a mono-exponential function. At a given circumferential stress, the corresponding strain values increased during the first 8 weeks of age (p < 0.05) where after no further change was observed. Hence, the small intestine became more compliant during early life. At a given longitudinal stress, the corresponding strains of ileum and duodenum became larger during the first 2-4 weeks of age (p < 0.05) where after no further change was observed. The small intestine was stiffer in longitudinal direction compared to the circumferential direction. In conclusion, pronounced morphometric and biomechanical changes were observed in the rat small intestine during physiological growth. Such data may prove useful in the understanding of the functional changes of the digestive tract during early life. 相似文献
114.
Zhong XB Leng L Beitin A Chen R McDonald C Hsiao B Jenison RD Kang I Park SH Lee A Gregersen P Thuma P Bray-Ward P Ward DC Bucala R 《Nucleic acids research》2005,33(13):e121
Microsatellite repeat and single nucleotide polymorphisms (SNPs) are abundant sources of genetic variation, but existing methodologies cannot simultaneously detect these variants in a facile or inexpensive way. We describe herein a thin-film biosensor chip based on an allele-discriminating oligonucleotide array that enables genotyping for both microsatellite repeats and SNPs in a single analysis. We validated this methodology for the functionally polymorphic −794 CATT5–8 repeat and −173 G/C SNP present in the promoter of the human gene for macrophage migration inhibitory factor (MIF). In a comparison of 30 samples collected at a rural hospital in Zambia, we observed a 100% concordance for both the CATT repeat and G/C SNP between the biosensor methodology and the conventional capillary electrophoresis. The biosensor chips are low in cost and once printed, they are robust and require no instrumentation for analysis. When combined with multiple displacement amplification, this methodology can be utilized in primitive settings for the genotyping of nanogram quantities of DNA present in blood, dried and stored on filter paper samples. We applied this methodology to a field study of MIF genotype in children with malaria, and provide first evidence for a potential association between MIF alleles and malaria infection. We also present data supporting significant population stratification of the low- versus high-expression forms of MIF that may bear on the role of this gene in infectious diseases. 相似文献
115.
Oligoclonality in the human CD8+ T cell repertoire in normal subjects and monozygotic twins: implications for studies of infectious and autoimmune diseases. 总被引:10,自引:4,他引:6 下载免费PDF全文
J. Monteiro R. Hingorani I. H. Choi J. Silver R. Pergolizzi P. K. Gregersen 《Molecular medicine (Cambridge, Mass.)》1995,1(6):614-624
BACKGROUND: We have previously demonstrated CD8+ T cell clonal dominance using a PCR assay for the CDR3 length of T cell receptors belonging to a limited number of TCRBV segments/families. In this study, we have modified this approach in order to analyze more comprehensively the frequency of oligoclonality in the CD8+ T cell subset in 25 known TCRBV segments/families. In order to assess the relative roles of genes and environment in the shaping of a clonally restricted CD8+ T cell repertoire, we have analyzed clonal dominance in the CD8+ T cell population of monozygotic twins, related siblings, and adoptees. MATERIALS AND METHODS: Oligoclonality was assessed in the CD8+ T cell subsets using a multiplex PCR approach to assay for CDR3 length variation across 25 different TCRBV segments/families. Specific criteria for oligoclonality were established, and confirmed by direct sequence analysis of the PCR products. This assay was used to investigate the CD8+ T cell repertoire of 56 normal subjects, as well as six sets of monozygotic (MZ) twins. RESULTS: Seventy-two percent of normal subjects (n = 56) had evidence of oligoclonality in the CD8+ T cell subset, using well-defined criteria. Although MZ twins frequently displayed CD8+ T cell clonal dominance, the overall pattern of oligoclonality was very diverse within each twin pair. However, we occasionally observed dominant CD8+ T cell clones that were highly similar in sequence in both members of some twin pairs. Not a single example of such similarity was observed in normal controls or siblings. CONCLUSIONS: Oligoclonality of circulating CD8+ T cells is a characteristic feature of the human immune system; both host genetic factors and environment shape the pattern of oligoclonality in this T cell subset. The high frequency of this phenomenon in normal subjects provides a background with which to evaluate CD8+ T cell oligoclonality in the setting of infection or autoimmune disease. Further phenotypic and functional characterization of these clonally expanded T cells should provide insight into normal immune homeostasis. 相似文献
116.
117.
Acyl-CoA:glycine N-acyltransferase: organelle localization and affinity toward straight- and branched-chained acyl-CoA esters in rat liver 总被引:1,自引:0,他引:1
Prompted by the fact that the urinary excretion of organic acids in the riboflavin-deficient rat closely mimics that found in patients with inborn errors in the acyl-CoA dehydrogenation systems, the organelle localization and the apparent kinetic constants (Km and Vmax values) for the rat liver acyl-CoA:glycine-N-acyltransferase (glycine-N-acylase) toward isobutyryl-CoA, 2-methylbutyryl-CoA, isovaleryl-CoA, butyryl-CoA, hexanoyl-CoA, octanoyl-CoA, decanoyl-CoA, and benzoyl-CoA were determined. The studies on organelle localization demonstrated that the glycine-N-acylase is exclusively an intramitochondrial enzyme, and that no activity is present in peroxisomes, which also possess ability to produce Acyl-CoAs. The kinetic studies were done in order to elucidate whether the quantitative differences in excretion profile of acylglycines between riboflavin-deficient rats and patients with beta-oxidation defects are caused by differences in ability to conjugate the various acyl-CoAs. It was found that the Km values for the rat liver enzyme were generally somewhat lower than the values found in man, but with the same chain length profile. Consequently, the above-mentioned differences in excretion profile of acylglycines between riboflavin-deficient rats and patients with beta-oxidation defects cannot be explained by differences in affinity toward the glycine-N-acylase. 相似文献
118.
Analysis of the molecular specificities of anti-class II monoclonal antibodies by using L cell transfectants expressing HLA class II molecules 总被引:4,自引:0,他引:4
E P Klohe R Watts M Bahl C Alber W Y Yu R Anderson J Silver P K Gregersen R W Karr 《Journal of immunology (Baltimore, Md. : 1950)》1988,141(6):2158-2164
Expressible HLA class II alpha- and beta-chain cDNA were used for DNA-mediated gene transfer to produce L cell transfectants expressing single types of human class II molecules. Cloned transfectants expressing nine different class II molecules were isolated: DR alpha: DR1 beta I, DR alpha: DR4 beta I, DR alpha: DR5 beta I, DR alpha: DR5 beta III (DRw52), DR alpha: DR7 beta I, DR alpha: DR4/7 beta IV (DRw53), DQ7 alpha: DQw2 beta, DQ7 alpha: DQw3 beta, and DPw4 alpha: DPw4 beta. These class II-expressing transfectants were used to analyze by flow cytometry the molecular specificities of 20 anti-class II mAb. These analyes indicate that some mAb are more broadly reactive than was previously thought based on immunochemical studies. In contrast, the narrow molecular specificities of other anti-class II mAb were confirmed by this approach. Transfectants expressing human class II molecules should be valuable reagents for studies of B cell and T cell defined epitopes on these molecules. 相似文献
119.
120.
Kathryn D Kavanagh Thrond O Haugen Finn Gregersen Jukka Jernvall L Asbjørn Vøllestad 《BMC evolutionary biology》2010,10(1):350