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391.
Ami Okada Tom Shin Eva Dworkin-Rastl Mark B. Dworkin Geoffrey Zubay 《Differentiation; research in biological diversity》1985,29(1):14-19
A study was undertaken to test for the occurrence of DNA rearrangements or amplifications during embryonic development in Xenopus laevis. DNA isolated from testes and liver was digested with four restriction enzymes, separated on agarose gels, transferred to nitrocellulose, and hybridized with over 50 cloned cDNA probes generated from embryonic poly (A)+ RNA. No qualitative or quantitative differences were detectable in the DNA hybridization patterns of testes and liver DNA, suggesting that, at least during liver development, selective amplifications or rearrangements occur rarely if at all. In the course of this investigation a wide range of restriction-site polymorphisms for different genes was observed. While some genes showed little polymorphism among different animals, several genes showed considerable polymorphism, involving changes in several restriction enzyme sites. These complex polymorphisms could be the result of gene rearrangements that occur occasionally during the course of sexual reproduction rather than during development. 相似文献
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Wafa Al-Kurdi-Norimine Fumiko Ochikubo Yasushi Ami Kazuya Yamanouchi Chieko Kai 《American journal of primatology》1994,33(4):301-308
Optimal conditions for the mitogen-induced proliferation of T and B lymphocytes of cynomolgus monkeys were determined. The T cell mitogens concanavalin A and phytohemagglutinin, at concentrations of 1.25–10 μg/ml and 1.25–10 μg/ml, respectively, and the T and B cell mitogen pokeweed mitogen, at concentrations of 0.2–10 μg/ml, induced high lymphoproliferative responses, the average stimulation index (SI) being 34–93. Since suitable mitogens have not been reported for monkey B cells, we tested three types of lipopolysaccharide (LPS): two derived from Escherichia coli—one extracted with phenol and one extracted with trichloroacetic acid (TCA); and one derived from Salmonella typhimurium, extracted with phenol. All three LPS had a high mitogenic effect for monkey lymphocytes, with SI of 2.3–6.4. The highest response was observed for 25 μg/ml of Salmonella LPS, and the addition of trypsin to the culture augmented the proliferative response of low or non-responder lymphocytes. © 1994 Wiley-Liss, Inc. 相似文献
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Ami Ben-Amotz 《Journal of phycology》1975,11(1):50-54
The holophilic alga Dunaliella parva produces glycerol as a major product of photosynthetic 14CO2 incorporation and accumulates very large amounts of intracellular glycerol. A method was adopted for the determination of the cell water space based on the distribution of 14C sorbitol and 3H2O between the cells and the medium. Using these measurements the internal concentration of glycerol was found to be isoomotic with that of the medium over a broad range of 0.6 to 2.1 m NaCl. When the extracellular salt concentration of an algal suspension was increased or decreased, the intracellular water content immediately varied so as to keep an osmotic equilibrium between the cells and the medium. During the following 90 min under metabolic conditions, glycerol content changed until a new level was reached. Since no leakage of intracellular glycerol was observed above 0.6 m NaCl, these alterations in glycerol content are interpreted as due to metabolic formation and degradation of intracellular glycerol. Determination of the glycerol sensitivity of enzymic and photosynthetic reactions of cell-free preparations from D. parva showed a broad range of tolerance to high concentrations of glycerol. These results indicate that osmoregulation in Dunaliella depends on the synthesis or degradation of intracellular glycerol in response to the external salt concentration. A proposed scheme of glycerol synthesis in Dunaliella is suggested. 相似文献