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191.
This paper examines the variability of the genital characters
ofHelix pomatia and H. lucorum. Some of these
characters are commonlyused to distinguish the two closely related
species. Variationswithin and between populations are also
investigated. The highvariability of these characters can frequently
lead to identificationerrors, especially in eastern Europe. Correct
identificationof these edible snails is also of commercial
importance, differentspecies having a different price. The reciprocal
nature of themale parts of the genitalia and the bursa stalk and
diverticulumcomplex is pointed out. A possible function of the
diverticulumis suggested on the basis of size relations between
genitalsystem features. (Received 12 August 1999; accepted 11 April 2000) 相似文献
192.
A Regulatory Mutant of Hansenula polymorpha Exhibiting Methanol Utilization Metabolism and Peroxisome Proliferation in Glucose
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![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Giuseppinia Parpinello Enrico Berardi Rosanna Strabbioli 《Journal of bacteriology》1998,180(11):2958-2967
Mutant LGM-128 of Hansenula polymorpha harbors the recessive mutation glr2-1 which confers a complex pleiotropic phenotype, the major feature of which is the metabolically unnecessary induction of methanol utilization metabolism (C1 metabolism) during growth on glucose, whether or not methanol is in the medium. Therefore, in this mutant, peroxisomes are formed and proliferate upon cultivation in glucose-containing media. In these media, LGM-128 shows induction levels of C1 metabolism that are similar to those observed in methanol-containing media. This indicates that GLR2 controls the repression-derepression process stimulated by glucose and that the induction process triggered by methanol plays only a minor role in activating C1 metabolism. Cultivating LGM-128 in methanol and then transferring it to glucose media revealed that active degradative processes occur, leading to the disappearance of C1 metabolism. This observation suggests that, although stimulated by glucose, the two processes are controlled by elements which are, at least in part, distinct. Finally, glr2-1 does not affect ethanol repression, suggesting that in H. polymorpha the two repressing circuits are separated. 相似文献
193.
G Protein β Subunit–null Mutants Are Impaired in Phagocytosis and Chemotaxis Due to Inappropriate Regulation of the Actin Cytoskeleton
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![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Barbara Peracino Jane Borleis Tian Jin Monika Westphal Jean-Marc Schwartz Lijun Wu Enrico Bracco Günther Gerisch Peter Devreotes Salvatore Bozzaro 《The Journal of cell biology》1998,141(7):1529-1537
Chemotaxis and phagocytosis are basically similar in cells of the immune system and in Dictyostelium amebae. Deletion of the unique G protein β subunit in D. discoideum impaired phagocytosis but had little effect on fluid-phase endocytosis, cytokinesis, or random motility. Constitutive expression of wild-type β subunit restored phagocytosis and normal development. Chemoattractants released by cells or bacteria trigger typical transient actin polymerization responses in wild-type cells. In β subunit–null cells, and in a series of β subunit point mutants, these responses were impaired to a degree that correlated with the defect in phagocytosis. Image analysis of green fluorescent protein–actin transfected cells showed that β subunit– null cells were defective in reshaping the actin network into a phagocytic cup, and eventually a phagosome, in response to particle attachment. Our results indicate that signaling through heterotrimeric G proteins is required for regulating the actin cytoskeleton during phagocytic uptake, as previously shown for chemotaxis. Inhibitors of phospholipase C and intracellular Ca2+ mobilization inhibited phagocytosis, suggesting the possible involvement of these effectors in the process. 相似文献
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Alessandro Grottesi Marco Sette Anna Teresa Palamara Giuseppe Rotilio Enrico Garaci Maurizio Paci 《Peptides》1998,19(10):1731-1738
The 28-residue peptide thymosin α1 was studied by circular dichroism and two-dimensional NMR. Circular dichroism indicates that thymosin α1 in water solution does not assume a preferred conformation, while in the presence of small unilamellar vesicles of dimiristoylphosphatidylcholine and dimiristoylphosphatidic acid (10:1) and in sodium dodecyl sulphate, it assumes a partly structured conformation. Presence of zinc ions produces similar effects. In a more hydrophobic environment like a solution of a mixed solvent water-2,2,2 trifluoroethanol, it adopts a structured conformation. NMR spectra indicated that in this mixture as solvent, thymosin α1 has a structure characterized by two regions. A β-turn is present between residue 5 and residue 8, while the region between residues 17 and 24 shows an α helix conformation. These changes of conformation in different environments may be considered structural requirements in the steps of its interaction with the lymphocyte membrane. In fact, these conformational changes may correspond to the first event of the mechanism of lymphocyte activation in the immune response modulation by thymosin α1. 相似文献
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199.
Neri Roncucci Nicoletta Nassi O Di Nasso Enrico Bonari Giorgio Ragaglini 《Global Change Biology Bioenergy》2015,7(5):998-1008
Biomass productivity is the main favorable trait of candidate bioenergy crops. Miscanthus × giganteus is a promising species, due to its high‐yield potential and positive traits including low nutrient requirements and potential for C sequestration in soils. However, miscanthus productivity appears to be mostly related to water availability in the soil. This is important, particularly in Mediterranean regions where the risk of summer droughts is high. To date, there have been no studies on miscanthus responses under different soil conditions, while only a few have investigated the role of different crop managements, such as irrigation and nitrogen fertilization, in the Mediterranean. Therefore, the effects of contrasting soil textures (i.e. silty‐clay‐loam vs. sandy‐loam) and alternative agricultural intensification regimes (i.e. rainfed vs. irrigated and 0, 50, 100 kg ha?1 nitrogen fertilization), on miscanthus productivity were evaluated at three different harvest times for two consecutive years. Our results confirmed the importance of water availability in determining satisfactory yields in Mediterranean environments, and how soil and site characteristics strongly affect biomass production. We found that the aboveground dry yields varied between 5 Mg ha?1 up to 29 Mg ha?1. Conversely, nitrogen fertilization played only a minor role on crop productivity, and high fertilization levels were relatively inefficient. Finally, a marked decrease, of up to ?40%, in the aboveground yield occurred when the harvest time was delayed from autumn to winter. Overall, our results highlighted the importance of determining crop responses on a site‐by‐site basis, and that decisions on the optimal harvest time should be driven by the biomass end use and other long‐term considerations, such as yield stability and the maintenance of soil fertility. 相似文献
200.
Integrating Phosphoproteome and Transcriptome Reveals New Determinants of Macrophage Multinucleation