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991.
Osteoblastic proliferative activity of Epimedium brevicornum Maxim. 总被引:19,自引:0,他引:19
The effect of the extracts of Epimedium brevicornum Maxim. was investigated on proliferative activity in vitro. The osteoblast-like UMR106 cells was employed as an osteoblast model. The EtOH extract and the n-butanol fraction from the crude extract were found to show proliferation stimulating activity. Three flavonoid compounds (icariin, epimedin B and epimedin C) were isolated from this fraction by activity-guided assay, and the effects on cell proliferation were studied. Icariin produced the most significant promoting effect on the proliferation in osteoblast-like UMR106 cells. The results suggested that E. brevicornum Maxim. extracts might have potential activity against osteoporosis, and flavonoids such as icariin might be the active constituents stimulating osteoblasts. 相似文献
992.
993.
994.
Twelve dwarf plants were found in the second hybrid generation of beet. The average height of mutant plants was 21.8 cm, their leaf blades and flowers were significantly smaller than normal, and the plants exhibited male and female sterility. This dwarfism was shown to be caused by a mutation differing from that previously described in beet, which is named dwarf2 (dw2). The experimental evidence suggests that this mutation appeared in one of the first-generation plants. Based on plant phenotype in the first hybrid generation and the number of mutant plants in the second one, this mutation is suggested to be under recessive monogenic control of the dw2 gene. The genotypic class segregation in the second hybrid generation indicates that the dw2 gene is inherited independently of genes m, a1, and ap that control choricarpousness, gene male sterility, and pollen grain aggregation into tetrads.__________Translated from Genetika, Vol. 41, No. 5, 2005, pp. 657–660.Original Russian Text Copyright © 2005 by Mglinets, Osipova. 相似文献
995.
Allopolyploidy in Wheat Induces Rapid and Heritable Alterations in DNA Methylation Patterns of Cellular Genes and Mobile Elements 总被引:2,自引:0,他引:2
Y. Z. Dong Z. L. Liu X. H. Shan T. Qiu M. Y. He B. Liu 《Russian Journal of Genetics》2005,41(8):890-896
Whereas accumulating recent evidences indicate that allopolyploid formation in plants is accompanied by rapid and non-Mendelian genomic changes, some other works showed genomic stasis in both nascent and natural allopolyploids. To further study the issue, we performed global DNA fingerprinting of a newly synthesized allohexaploid wheat and its natural counterpart, the common wheat, by AFLP analysis. It was found that ca. 20% bands showed deviation from parental additivity in both synthetic and natural common wheat. Sequence analysis indicates that a majority of the changed bands represent known-function genes and transposable elements. DNA gel blot analysis showed that the main type of changes in the amphiploid is epigenetic in nature, i.e., alteration in DNA methylation patterns. Two types of alterations in methylation, random and non-random, were detected, and both types were stably inherited. Possible causes and implications of the epigenetic changes in allopolyploid genome evolution and speciation are discussed.__________From Genetika, Vol. 41, No. 8, 2005, pp. 1089–1095.Original English Text Copyright © 2005 by Dong, Liu, Shan, Qiu, He, Liu.This text was submitted by the authors in English. 相似文献
996.
Jordan D. R. Tao Y. Z. Godwin I. D. Henzell R. G. Cooper M. McIntyre C. L. 《Molecular breeding : new strategies in plant improvement》2005,14(4):441-454
Seventy sorghum inbred lines which formed part of the Queensland Department of Primary Industries (QDPI) sorghum breeding program were screened with 104 previously mapped RFLP markers. The lines were related by pedigree and consisted of ancestral source lines, intermediate lines and recent releases from the program. We compared the effect of defining marker alleles using either identity by state (IBS) or identity by descent (IBD) on our capacity to trace markers through the pedigree and detect evidence of selection for particular alleles. Allelic identities defined using IBD were much more sensitive for detecting non-Mendelian segregation in this pedigree. Only one marker allele showed significant evidence of selection when IBS was used compared with ten regions with particular allelic identities when IBD was used. Regions under selection were compared with the location of QTLs for agronomic traits known to be under selection in the breeding program. Only two of the ten regions were associated with known QTLs that matched with knowledge of the agronomic characteristics of the ancestral lines. Some of the other regions were hypothesised to be associated with genes for particular traits based on the properties of the ancestral source lines. 相似文献
997.
Amino acid oxidases, which enantiospecifically catalyze the oxidative deamination of either D‐ or L‐amino acids, belong to the class of oxidoreductases functioning with a tightly bound cofactor. This cofactor favors industrial applications of D‐amino acid oxidases (D‐AAO). Hence, the enzyme is very important for the industrial application in the purification and determination of certain amino acids. In developing the enzyme‐catalyzed reaction for large‐scale production, modeling of the reaction kinetics plays an important role. Therefore, the subject of this study was the kinetics of the oxidative deamination, a very complex reaction system, which is catalyzed by D‐AAO from Arthrobacter protophormiae using its natural substrate D‐methionine and the aromatic amino acid 3,4‐dihydroxyphenyl‐D‐alanine (D‐DOPA). The kinetic parameters determined by the measurement of the initial rate and nonlinear regression were verified in batch reactor experiments by comparing calculated and experimental concentration‐time curves. It was found that the enzyme is highly specific towards D‐methionine (Km = 0.24 mM) and not as specific to D‐DOPA as a substrate (Km = 9.33 mM). The enzyme activity towards D‐methionine ( = 3.01 U/mL) was approx. seven times higher than towards D‐DOPA ( = 20.01 U/mL). The enzyme exhibited no activity towards L‐methionine and L‐DOPA. Batch and repetitive batch experiments were performed with both substrates in the presence and in the absence of catalase for hydrogen peroxide decomposition. Their comparison made it possible to conclude that hydrogen peroxide has no negative influence on the enzyme activity. 相似文献
998.
999.
Soluble Organic Nitrogen Pools in Forest soils of Subtropical Australia 总被引:15,自引:0,他引:15
Soil soluble organic N (SON) plays an important role in N biogeochemical cycling. In this study, 22 surface forest soils (0–10 cm)
were collected from southeast Queensland, Australia, to investigate the size of SON pools extracted by water and salt solutions.
Approximately 5–45 mg SON kg−1, 2–42 mg SON kg−1 and 1–24 SON mg kg−1 were extracted by 2 M KCl, 0.5 M K2SO4 and water, on average, corresponding to about 21.1, 13.5 and 7.0 kg SON ha−1 at the 0–10 cm forest soils, respectively. These SON pools, on average, accounted for 39% (KCl extracts), 42% (K2SO4 extracts) and 43% (water extracts) of total soluble N (TSN), and 2.3% (KCl extracts), 1.3% (K2SO4 extracts) and 0.7% (water extracts) of soil total N, respectively. Large variation in SON pools observed across the sites
in the present study may be attributed to a combination of factors including soil types, tree species, management practices
and environmental conditions. Significant relationships were observed among the SON pools extracted by water, KCl and K2SO4 and microbial biomass N (MBN). In general, KCl and K2SO4 extracted more SON than water from the forest soils, while KCl extracted more SON than K2SO4. The SON and soluble organic C (SOC) in KCl, K2SO4 and water extracts were all positively related to soil organic C, total N and clay contents. This indicates that clay and
soil organic matter play a key role in the retention of SON in soil. 相似文献
1000.
Effects of water stress and high nocturnal temperature on photosynthesis and nitrogen level of a perennial grass Leymus chinensis 总被引:5,自引:0,他引:5
Water deficit and high temperature are important environmental factors restricting plant growth and photosynthesis. The two
stresses often occur simultaneously, but their interactions on photosynthesis and nitrogen level have been less studied. In
the present experiment, we measured photosynthetic parameters, stomatal density, and nitrogen levels, as well as soluble sugar
content of leaves of a perennial grass, Leymus chinensis, experiencing two day/night temperature regimes of 30/20 °C and 30/25 °C, and five different soil moisture contents (the
soil relative-water content ranged from 80% to 25%). Leaf relative water content, leaf biomass, whole plant biomass, the ratio
between the leaf biomass and total plant biomass, and the photosynthetic rate, as well as water-use efficiency decreased at
high night temperature, especially under severe water stress conditions. Stomatal index was also increased by soil water stress
except very severe water stress, and high nocturnal temperature decreased the leaf stomatal index under soil water stress.
Nocturnal warming decreased nitrogen concentration in the leaves and increased it in the roots, particularly when plants were
subjected to severe water stress. There were significant positive correlations between the photosynthetic rate and both soluble
sugar concentration and nitrogen concentration at low nocturnal temperature. It is suggested that nocturnal warming significantly
exacerbates the adverse effects of soil water stress, and their synergistic interactions might reduce the plant productivity
and constrain its distribution in the region dominated by L. chinensis, based on predictions of global climate change. 相似文献