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991.
Isozyme patterns of carrot (Daucus carota L.) zygotic embryos between the torpedo stage up to 5-day-old seedlings have been compared with those of the similar stages from the embryogenic cell suspension culture to the late somatic plantlet. Somatic embryos blocked at the torpedo stage by -cyclodextrine have also been analyzed. All these stages have been analyzed with respect to seven different enzyme systems: arylesterase, glucosephosphate isomerase, phosphogluconate dehydrogenase, alcohol dehydrogenase, isocitrate dehydrogenase, aspartate aminotransferase and phosphoglucomutase (EC 2.7.5.1, PGM). The relationships between the different stages of both types of embryogenesis have been visualized using an unrooted tree. Generally, profiles of somatic embryos were different from those of zygotic embryos. Interestingly however, a typical zygotic embryo pattern was found in the cyclodextrine-blocked somatic embryos. Only aspartate aminotransferase patterns revealed a similarity between zygotic and somatic torpedo embryos. Both plantlet types showed close patterns with common isozymes. Moreover, similarities were evident between somatic plantlets and cell suspensions. A few isozymes appeared to be stage specific markers: esterase 10–11 were specific to achenes and early germination, phosphogluconate dehydrogenase 8 was specific to 4–5 day-old seedlings and phosphoglucomutase 1 and 7 and alcohol dehydrogenase 4 were markers for zygotic embryos. No somatic embryogenesis specific isozyme could be found. We show that patterns can be associated with particular tissue formation: mainly, aspartate aminotransferase 2 and 1, phosphoglucomutase 8 and 9 and phosphogluconate dehydrogenase 7 coincided with apical meristem initiation and phosphoglucomutase 4 and 5, zones b and d of esterase and zone b of phosphogluconate dehydrogenase coincided with vascular bundle formation.Abbreviations ADH
alcohol dehydrogenase
- CD
-cyclodextrine
- CS
cell suspension culture
- 2,4-D
2,4-dichlorophenoxyacetic acid
- EDTA
ethylenediaminetetraaeetie acid
- LiBo
lithium hydroxide/boric acid
- PEG
polyethylene glycol
- PVP
polyvinylpyrrolidone
- SEg
somatic embryo at the globular stage
- SEh
heart stage
- SEte
early torpedo stage
- SEtl
late torpedo stage
- SEce
early cotyledonary stage
- SEcl
late cotyledonary stage
- SECD
somatic embryo blocked at the torpedo stage with -cyclodextrine
- EST
esterase
- GOT
aspartate aminotransferase
- IDH
isocitrate dehydrogenase
- MTT
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide)
- PMS
phenazonium methosulfate
- PGD
phosphogluconate dehydrogenase
- PGI
glucosephosphate isomerase
- PGM
phosphoglucomutase
- SO
dry seed
- S1–3
seed after 1–3 days of germination
- SP1–2
young and old somatic plantlets
- ZE
zygotic embryo
- ZP4–5
4–5 day-old seedlings 相似文献
992.
Lorraine Racine-Samson Jean-Yves Scoazec Alain Moreau Laurence Christa Dominique Bernuau Gérard Feldmann 《Histochemistry and cell biology》1996,105(4):319-329
The coexpression of normally periportal and perivenous markers has been described in heterotopically transplanted hepatocytes. To determine whether such a coexpression might also occur in hepatocytes retaining their original intrahepatic location, we compared in bileduct-ligated livers and intrasplenically transplanted hepatocytes, the expression and distribution of the predominantly periportal glucose-6-phosphatase, succinate dehydrogenase, and lactate dehydrogenase, the predominantly perivenous glutamate dehydrogenase, NADPH-dehydrogenase, and -hydroxybutyrate dehydrogenase, and the strictly perivenous glutamine synthetase. The coexpression of high levels of the two periportal markers glucose-6-phosphatase and lactate dehydrogenase and of the perivenous marker NADPH dehydrogenase was observed in two situations: in clusters of hepatocytes isolated within the ductular proliferation in bile-duct-ligated livers and the majority of intrasplenically transplanted hepatocytes. The expression of glutamine synthetase was different according to the site. The protein was observed in certain intrasplenically transplanted hepatocytes bordering the splenic vessels but was never detected in hepatocyte clusters found in bile-duct-ligated livers. Our study therefore suggests that the coexpression of periportal and perivenous markers in the same hepatocytes is likely to be a non-specific consequence of the loss of the normal connections of hepatocytes with the normal liver microcirculation. 相似文献
993.
994.
Laurence Blanchard C. Neil Hunter Michael P. Williamson 《Journal of biomolecular NMR》1997,9(4):389-395
Calculations suggest that some carbon chemical shifts in proteinsshould have large ring current shifts (>1 ppm). We present13C, 15N and 1H assignments forcytochrome c2 from Rhodospirillum rubrum, compare these withshifts for other cytochromes c, and show that the calculated ring currentshifts are similar to experimentally observed shifts, but that there remainsubstantial conformation-dependent shifts of side-chain carbons. Ringcurrent shifts as large as 6 ppm are observed. We show that the ring currenteffects do not seriously affect the Chemical Shift Index method fordelineating secondary structure, but may have an impact on more precisemethods for generating structural constraints. 相似文献
995.
An illustrated identification system is presented to 99 species and 49 genera in three families recorded from the Hawaiian Islands in the Thysanoptera suborder Terebrantia. Only seven (possibly eight) of these species are considered endemic, the remainder being adventive to these islands. The only previous study of Hawaiian Thysanoptera, by Zimmerman in 1948, included 47 Terebrantia species in 21 genera. 相似文献
996.
997.
998.
Laurence Mathieu Grégory Francius Racha El Zein Edith Angel Jean-Claude Block 《Biofouling》2016,32(8):925-934
The short-term kinetics of bacterial repopulation were evaluated after chlorination of high-density polyethylene (HDPE) colonized with drinking water biofilms and compared with bare HDPE surfaces. The effect of chlorination was partial as a residual biofilm persisted and was time-limited as repopulation occurred immediately after water resupply. The total number of bacteria reached the same levels on both the bare and chlorinated biofilm-fouled HDPE after a seven-day exposure to drinking water. Due to the presence of a residual biofilm, the hydrophobicity of chlorinated biofilm-fouled surface exhibited much lower adhesion forces (2.1 nN) compared to bare surfaces (8.9 nN). This could explain the rapid repopulation after chlorination, with a twofold faster bacterial accumulation rate on the bare HDPE surface. γ-Proteobacteria dominated the early stages of repopulation of both surfaces and a shift in the dominance occurred over the colonization time. Such observations define a timescale for cleaning frequency in industrial environments and guidelines for a rinsing procedure using drinking water. 相似文献
999.
Joana Rocha Joe Sarkis Aline Thomas Laurence Pitou Jens Radzimanowski Magali Audry Valérie Chazalet Daniele de Sanctis Monica M. Palcic Maryse A. Block Agnès Girard‐Egrot Eric Maréchal Christelle Breton 《The Plant journal : for cell and molecular biology》2016,85(5):622-633
Monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are the major lipid components of photosynthetic membranes, and hence the most abundant lipids in the biosphere. They are essential for assembly and function of the photosynthetic apparatus. In Arabidopsis, the first step of galactolipid synthesis is catalyzed by MGDG synthase 1 (MGD1), which transfers a galactosyl residue from UDP‐galactose to diacylglycerol (DAG). MGD1 is a monotopic protein that is embedded in the inner envelope membrane of chloroplasts. Once produced, MGDG is transferred to the outer envelope membrane, where DGDG synthesis occurs, and to thylakoids. Here we present two crystal structures of MGD1: one unliganded and one complexed with UDP. MGD1 has a long and flexible region (approximately 50 amino acids) that is required for DAG binding. The structures reveal critical features of the MGD1 catalytic mechanism and its membrane binding mode, tested on biomimetic Langmuir monolayers, giving insights into chloroplast membrane biogenesis. The structural plasticity of MGD1, ensuring very rapid capture and utilization of DAG, and its interaction with anionic lipids, possibly driving the construction of lipoproteic clusters, are consistent with the role of this enzyme, not only in expansion of the inner envelope membrane, but also in supplying MGDG to the outer envelope and nascent thylakoid membranes. 相似文献