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Joong Kyu Kim Mark Klinger Jonathan Benjamin Yuanyuan Xiao David J. Erle Dan R. Littman Nigel Killeen 《PloS one》2009,4(8)
Signaling through the T cell antigen receptor (TCR) is important for the homeostasis of naïve and memory CD4+ T cells. The significance of TCR signaling in regulatory T (Treg) cells has not been systematically addressed. Using an Ox40-cre allele that is prominently expressed in Treg cells, and a conditional null allele of the gene encoding p56Lck, we have examined the importance of TCR signaling in Treg cells. Inactivation of p56Lck resulted in abnormal Treg homeostasis characterized by impaired turnover, preferential redistribution to the lymph nodes, loss of suppressive function, and striking changes in gene expression. Abnormal Treg cell homeostasis and function did not reflect the involvement of p56Lck in CD4 function because these effects were not observed when CD4 expression was inactivated by Ox40-cre.The results make clear multiple aspects of Treg cell homeostasis and phenotype that are dependent on a sustained capacity to signal through the TCR. 相似文献
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Cory Bystrom Shijun Sheng Ke Zhang Michael Caulfield Nigel J. Clarke Richard Reitz 《PloS one》2012,7(9)
Measurement of insulin-like growth factor-1 (IGF-I) has utility for the diagnosis and management of growth disorders, but inter-assay comparison of results has been complicated by a multitude of reference standards, antibodies, detection methods, and pre-analytical preparation strategies. We developed a quantitative LC-MS method for intact IGF-I, which has advantages in throughput and complexity when compared to mass spectrometric approaches that rely on stable isotope dilution analysis of tryptic peptides. Since the method makes use of full-scan data, the assay was easily extended to provide quantitative measurement of IGF-II using the same assay protocol. The validated LC-MS assay for IGF-I and IGF-II provides accurate results across the pediatric and adult reference range and is suitable for clinical use. 相似文献
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The present study reports the isolation and characterization of a cadmium-containing glycoprotein from the water-soluble fraction of an aquatic insect. The isolated glycoprotein contained 0·67% cadmium, 62·1% carbohydrate, and 37·2% protein. The glycoprotein appears to be involved in the detoxification of cadmium, because species insensitive to cadmium contain five times the amount of the glycoprotein as do species sensitive to cadmium. 相似文献
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Moran Jonathan A.; Merbach Marlis A.; Livingston Nigel J.; Clarke Charles M.; Booth Webber E. 《Annals of botany》2001,88(2):307-311
Old World pitcher plants (Nepenthes spp., Nepenthaceae) trapand digest invertebrate prey to derive nutrients, primarilynitrogen (N). In the majority of lowland Nepenthes species studiedto date, ants (Hymenoptera, Formicidae) are numerically thedominant prey taxon. Nepenthes albomarginata is unusual in showingan apparent bias towards the capture of termites (Isoptera).We tested the hypothesis that N. albomarginata derives N fromtermite capture, by comparison of foliar stable N isotope abundance( 相似文献
9.
Homozygous lymphoblastoid cell lines representing various Dw subtypes of DR2 were examined for polymorphism at the DQ
locus by molecular and cellular techniques. The subtypes studied included Dw2, Dw12, and a group heterogenous by cellular typing that we shall refer to as non-Dw2/non-Dw12. Restriction fragment length polymorphism analysis of cell lines representing these subtypes revealed DQ
-specific patterns consistent with cellular typing. Two-dimensional gel electrophoresis of DQ molecules from representative cell lines revealed a structural polymorphism of DQ
among the three subtypes. The DQ
chain migrated to a position that was unique to each subtype and was consistent among various representative cell lines of each subtype. Nucleotide sequence analysis of cDNA clones of DQ
from Dw2, Dw12, and non-Dw2/non-Dw12 lines confirmed that the variability resided at the genetic level. Variability was found in the form of numerous scattered nucleotide substitutions throughout the first domain of these alleles. The DQ
gene of the non-Dw2/non-Dw12 cell line AZH was further found to be almost identical with the DQ
gene of a DR1 line (Bell et al. 1985b), implicating a common evolutionary origin of these alleles. The only difference between these two sequences was due to an apparent gene conversion event at amino acid 57. T-cell cloning experiments resulted in the derivation of Epstein-Barr virus-specific, DQw1-restricted clones that proliferated against only those cell lines that exhibited the DQ
gene common to AZH and the DR1 cell line. Thus, the polymorphism among DQ
alleles within DR2 results in subtype-specific restriction. 相似文献
10.
Nigel W. Kerby Gordon W. Niven Peter Rowell William D. P. Stewart 《Applied microbiology and biotechnology》1987,25(6):547-552
Summary Mutant strains of the N2-fixing cyanobacterium bacterium Anabaena variabilis resistant to 6-fluorotryptophan or to ethionine were isolated. Many of these strains liberated amino acids into their media in the absence of 6-fluorotryptophan and ethionine. Nitrogenase activity was higher in mutant strains than in the parent strain. Mutant strains were immobilised in calcium alginate and sustained photoproduction of amino acids has been demonstrated.Abbreviations ETH
ethionine
- FT
6-fluorotryptophan
- Hepes
4-(2-hydroxyethyl)-1, piperazine ethanesulphonic acid
- PEP
phosphoenolpyruvate
- DAHP
3-deoxy-d-arabinoheptulosonate 7-phosphate
- chl a
chlorophyll a 相似文献