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41.
42.
JUSTIN A. PITT SERGE LARIVIÈRE FRANÇOIS MESSIER 《The Journal of wildlife management》2008,72(2):389-395
ABSTRACT We investigated the influence of intrinsic and extrinsic variables on overwinter survival of raccoons (Procyon lotor; n = 114) at the northern edge of their distribution. A Cox proportional hazard model identified winter severity as the variable with the greatest influence on raccoon survival (β = 1.08). Autumn body condition estimates (20.5 ± 0.46% total body fat) were relatively stable across years even though we observed large differences in autumn food indices. Variations in autumn body condition did not explain heterogeneity observed in overwinter survival nor the spring condition in which raccoons emerged. Relatively constant autumn body condition suggests reliable availability of anthropogenic food resources may negate variations observed in natural food items on which raccoons rely during hyperphagia. Conversely, spring body condition did vary among years and was highly correlated with winter severity. Accordingly, we also observed a strong inverse relationship with overwinter survival and winter severity. Our findings indicate winter climatic constraints are important factors governing the northern limit of raccoon distribution and changes in winter severity could have important implications in further range expansion of this species. 相似文献
43.
Calmodulin has been isolated and characterized from the gill of the bay scallop aequipecten irradians. Quantitative electrophoretic analysis of epithelial cell fractions show most of the calmodulin to be localized in the cilia, specifically in the detergent- solubilized membrane-matrix fraction. Calmodulin represents 2.2 +/- 0.3 percent of the membrane-matrix protein or 0.41 +/- 0.5 percent of the total ciliary protein. Its concentration is at least 10(-4) M if distributed uniformly within the matrix. Extraction in the presence of calcium suggests that the calmodulin is not bound to the axoneme proper. The ciliary protein is identified as a calmodulin on the basis of its calcium- dependent binding to a fluphenazine-sepharose affinity column and its comigration with bovine brain calmodulin on alkaline-urea and SDS polyacrylamide gels in both the presence and absence of calcium. Scallop ciliary calmodulin activates bovine brain phosphodiesterase to the same extent as bovine brain and chicken gizzard calmodulins. Containing trimethyllysine and lacking cysteine and tryptophan, the amino acid composition of gill calmodulin is typical of known calmodulins, except that it is relatively high in serine and low in methionine. Its composition is less acidic than other calmodulins, in agreement with an observed isoelectric point approximately 0.2 units higher than that of bovine brain. Comparative tryptic peptide mapping of scallop gill ciliary and bovine brain calmodulins indicates coincidence of over 75 percent of the major peptides, but at least two major peptides in each show no near-equivalency. Preliminary results using ATP-reactivated gill cell models show no effect of calcium at micromolar levels on ciliary beat or directionality of the lateral cilia, the cilia which constitute the vast majority of those isolated. However, ciliary arrest will occur at calcium levels more than 150 muM. Because calmodulin usually functions in the micromolar range, its role in this system is unclear. Scallop gill ciliary calmodulin may be involved in the direct regulation of dyneintubule sliding, or it may serve some coupled calcium transport function. At the concentration in which it is found, it must also at least act as a calcium buffer. 相似文献
44.
Relationship between the Geotropic Response and the Evolution of the Statenchyma in Roots of Asparagus officinalis. The evolution of the statenchyma in roots of Asparagus of ficinalis seedlings, grown in obscurity, was followed during the first 17 days. After 7 days of etiolation, a decrease of both the average diameter of the amyloplasts and the average number of these organelles was observed in the central root cap cells. If the seedlings were illuminated (with white light) from the 7th day, the average number of statoliths increased rapidly in the statocytes. The volume of these organelles undergoes the same variation in etiolated and in illuminated plants. The initial rate of curvature (Vi) of the roots (stimulated in a horizontal position) and the volume of amyloplasts (Vac) in their caps were analysed as a function of the time of germination in obscurity (from the 8th to the 17th day). It was found that Vi increased as a linear function of the logarithm of Vac, which confirms that the weight of the amyloplasts of the statocytes may play a role in the geotropic stimulation of the roots. 相似文献
45.
JEAN-FRANÇOIS RIOU DE-LI SHI THIERRY DARRIBÈRE JEAN-CLAUDE BOUCAUT JACQUES CHARLEMAGNE 《Development, growth & differentiation》1987,29(5):443-454
We have previously reported the identification of cell surface glycoproteins in Pleurodeles waltlii gastrulae. In an attempt to study the expression of three of these cell surface glycoproteins (proteins referred to 1, 11 and 14), we have produced monoclonal and polyclonal antibodies by immunizing mice with the spots of the three selected glycoproteins excised from 2D-gels. Expression of the three glycoproteins was detected on the surfaces of all cells during embryonic development. Before hatching, proteins 1, 11 and 14 become expressed in a limited number of tissues. 相似文献
46.
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48.
STÉPHANIE DEPICKÈRE G. MARCELO RAMÍREZ ÁVILA DOMINIQUE FRESNEAU JEAN-LOUIS DENEUBOURG 《Ecological Entomology》2008,33(2):225-231
Abstract. 1. Aggregation of individuals, a basic behaviour in social species, plays an essential role in many aspects of animal life (reproduction, defence, and alimentation). Understanding how this phenomenon is modulated is important to comprehend the social organisation of the group.
2. In social insects, aggregation is influenced by environmental (e.g. the light level) and social (e.g. polyethism in monomorphic ants) factors. Ants display a great variation of biological characteristics (e.g. queen number, polymorphism, division of labour, etc.) that are likely to influence the level of inter-attraction and so the aggregation.
3. The present research focused on one biological characteristic: the morphological castes (minors, majors), testing the hypothesis that minors will aggregate more than majors due to their greater need to fight against the loss of heat and to increase their self-protection.
4. Aggregation experiments were conducted on two highly polymorphic species, Atta sexdens rubropilosa and Solenopsis interrupta , using the two extreme morphological castes (majors and minors).
5. All castes exhibited a low level of aggregation: 40–50% of workers assembled for both species, the biggest cluster involving 20% of the total population. The lack of difference between morphological castes in the aggregation shows the weak influence of polymorphism on the interactions between ants.
6. It is concluded that the main factor modulating the aggregation behaviour is polyethism, i.e. the division of labour associated with the presence of an outside-the-nest experience: workers that only take care of the brood, without outside world experience (brood-tenders) assembling more than foraging workers (foragers). 相似文献
2. In social insects, aggregation is influenced by environmental (e.g. the light level) and social (e.g. polyethism in monomorphic ants) factors. Ants display a great variation of biological characteristics (e.g. queen number, polymorphism, division of labour, etc.) that are likely to influence the level of inter-attraction and so the aggregation.
3. The present research focused on one biological characteristic: the morphological castes (minors, majors), testing the hypothesis that minors will aggregate more than majors due to their greater need to fight against the loss of heat and to increase their self-protection.
4. Aggregation experiments were conducted on two highly polymorphic species, Atta sexdens rubropilosa and Solenopsis interrupta , using the two extreme morphological castes (majors and minors).
5. All castes exhibited a low level of aggregation: 40–50% of workers assembled for both species, the biggest cluster involving 20% of the total population. The lack of difference between morphological castes in the aggregation shows the weak influence of polymorphism on the interactions between ants.
6. It is concluded that the main factor modulating the aggregation behaviour is polyethism, i.e. the division of labour associated with the presence of an outside-the-nest experience: workers that only take care of the brood, without outside world experience (brood-tenders) assembling more than foraging workers (foragers). 相似文献
49.
Abstract. 1. Sexual conflict can play an important role in the evolution of animal life-history characteristics, including lifespan. Seaweed flies show an increase in mortality rates when exposed to brown algae. The seaweed stimulates females to oviposit and males to mount females. Females typically respond to male mounts by performing a violent rejection response.
2. Here the contribution of sexual conflict to the increase in mortality seen in the presence of seaweed was determined. The survival of single and mixed sex pairs of flies was followed in the presence and absence of seaweed.
3. The two sexes showed differential survival rates, with females living longer in the absence of seaweed. The presence of seaweed reduced survival in both sexes. In the presence of seaweed, female survival was lower when paired with a male. Over 40% of the reduction in survival in females in the presence of seaweed appears to be attributable to sexual conflict.
4. The presence of a female did not significantly affect male survival. Thus the mortality cost of being in the presence of the opposite sex and seaweed appears highly asymmetric.
5. In the presence of seaweed, female survival was lower when females were paired with small males. Small males exhibit higher levels of harassment of females, thus it is argued that pre-copulatory sexual conflict is the probable cause of the increased mortality cost to females of being in the presence of both males and seaweed. 相似文献
2. Here the contribution of sexual conflict to the increase in mortality seen in the presence of seaweed was determined. The survival of single and mixed sex pairs of flies was followed in the presence and absence of seaweed.
3. The two sexes showed differential survival rates, with females living longer in the absence of seaweed. The presence of seaweed reduced survival in both sexes. In the presence of seaweed, female survival was lower when paired with a male. Over 40% of the reduction in survival in females in the presence of seaweed appears to be attributable to sexual conflict.
4. The presence of a female did not significantly affect male survival. Thus the mortality cost of being in the presence of the opposite sex and seaweed appears highly asymmetric.
5. In the presence of seaweed, female survival was lower when females were paired with small males. Small males exhibit higher levels of harassment of females, thus it is argued that pre-copulatory sexual conflict is the probable cause of the increased mortality cost to females of being in the presence of both males and seaweed. 相似文献
50.
Austin RJ Kuestner RE Chang DK Madden KR Martin DB 《Journal of proteome research》2011,10(11):5251-5259
The methylotrophic yeast Pichia pastoris is a powerful eukaryotic platform for the production of heterologous protein. Recent publication of the P. pastoris genome has facilitated strain development toward biopharmaceutical and environmental science applications and has advanced the organism as a model system for the study of peroxisome biogenesis and methanol metabolism. Here we report the development of a P. pastoris arg-/lys- auxotrophic strain compatible with SILAC (stable isotope labeling by amino acids in cell culture) proteomic studies, which is capable of generating large quantities of isotopically labeled protein for mass spectrometry-based biomarker measurements. We demonstrate the utility of this strain to produce high purity human serum albumin uniformly labeled with isotopically heavy arginine and lysine. In addition, we demonstrate the first quantitative proteomic analysis of methanol metabolism in P. pastoris, reporting new evidence for a malate-aspartate NADH shuttle mechanism in the organism. This strain will be a useful model organism for the study of metabolism and peroxisome generation. 相似文献