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1.
The morphological, metrical, and discriminant function analysis of a phalanx from the Lower Pleistocene site of Cueva Victoria suggests that it differs significantly from carnivores and non-human primate groups, and closely resembles theHomo group studied. The phalanx has been classified as a IInd. phalanx of the 5th. finger of the right hand.  相似文献   

2.
New skeletal elements are reported of the holotype specimen Australovenator wintonensis, from the type locality, near Winton, central western Queensland. New elements include left and right humeri, right radius, right radiale, right distal carpal 1, near complete right metacarpal I, left manual phalanx II-1, left manual phalanx II-2, near complete left manual phalanx II-3 and a left manual phalanx III-3. These new elements combined with those previously described are compared against other neovenatorids.  相似文献   

3.
辽宁西部早白垩世义县组一新的手盗龙类(英文)   总被引:5,自引:0,他引:5  
我国辽西早白垩世热河群义县组和九佛堂组近年来产出大量恐龙化石 ,已知兽脚类恐龙包括 8属 1 0种 ,其中 6属 8种保存有原始羽毛或者羽毛结构。已经报道的属种均产自朝阳地区。 2 0 0 1年 ,中国科学院古脊椎动物与古人类研究所辽西野外考察队在邻近朝阳的锦州地区义县头台乡王家沟义县组下部采集到一件恐龙标本。这一标本保存了较为完整的肩带和前肢 ,在骨骼化石附近还保存了皮肤结构。通过研究对比 ,我们建立了手盗龙类的一个新属种 :长掌义县龙 (Yixianosauruslongimanusgen .etsp .nov .)。依据以下特征将长掌义县龙归入手盗龙类 :肩胛骨明显短于肱骨、肩臼窝的乌喙骨部分小、乌喙骨近四方形、尺骨向后弯曲以及挠骨细。长掌义县龙手部的相对长度以及手指各指节的相对比例不同于已知手盗龙类。原始兽脚类恐龙的手部一般短于肱骨 ;手盗龙手部加长 ,长于肱骨 ;原始鸟类的手部相对更长 ,但进步鸟类出现反转 ,手部次生变短。长掌义县龙手部的相对长度在非鸟兽脚类恐龙当中仅比原始祖鸟 (Protarchaeopteryx) (Jietal.,1 998)和树息龙 (Epidendrosaurus) (Zhangetal.,2 0 0 2 )短。次末端指节加长是兽脚类恐龙的一个进步特征 ,长掌义县龙具有这一特征。比如 ,长掌义县龙的手指指节Ⅱ 2长于掌骨Ⅱ ,在已知兽?  相似文献   

4.
The nonelectrolyte (Js) and volume (Jv) flux across a membrane is usually described in terms of two equations derived from the theory of irreversible thermodynamics: (see article) where delta c and delta P are the concentration and pressure difference; omega and Lp are the diffuse and hydraulic permeability; and sigma s and sigma v are the reflection coefficients. If Onsager's reciprocity postulate is assumed, it can be shown that signa s and sigma v are equal. This is an important assumption because it allows one to apply the continuum theory relationship between sigma s and the pore radius to experimental measurements of sigma v. In this paper, general continuum expressions for both the Jv (a new result) and Js equation will be derived and the equality of sigma s and sigma v proved. The proof uses only general hydrodynamic results and does not require explicit solutions for the drag coefficients or, for example, the assumption that the solute is in the center of the pore. The proof applys to arbitrarily shaped solutes and any pore whose shape is independent of axial position (uniform). In addition, new expressions for the functional dependence of omega and sigma on the pore radius are derived (including the effect of the particle lying off the pore axis). These expressions differ slightly from earlier results and are probably more accurate.  相似文献   

5.
This paper reports on newly developed ecomorphological models for the cervid intermediate phalanx. Using a geometric morphometric approach, we quantitatively assess the overall gracility of the bone, the depth and concavity of the proximal articulation and the roundness and symmetry of the distal articulation in the intermediate phalanx, to establish relationships between morphology, locomotor behavior and environment. The morphology of the phalanx was found to vary along a gradient from gracile phalanges with shallow proximal articulations in forms adapted to yielding substrate, to robust phalanges with deeper proximal articulations in taxa adapted to firm substrate. Phylogeny and allometry are accounted for using regressions and phylogenetic comparative methods. Although the results indicate phylogeny explains part of the morphological variation, overall the shape of the intermediate phalanx appears mainly driven by differences in function. Consequently, this element promises to be a useful palaeoenvironmental proxy that can be applied on fossil assemblages with cervid remains.  相似文献   

6.
刘凤红  刘建  董鸣 《生态学报》2005,25(12):3415-3419
克隆植物根据其构型可以分为游击型和密集型。游击型克隆植物的间隔子长,分株在水平空间的扩展范围大,可以利用更大空间范围内的资源,其通过克隆生理整合作用发生的非局部反应的能力强。由此可以得出的推论之一是,小生境斑块的环境发生变化,生长于其中的密集型克隆植物的反应可能会更灵敏。这种反应可能会体现在生物量以及配置格局的变化上。以毛乌素地区沙生半灌木群落中两种优势克隆植物羊柴(H edy sarum laeve)和油蒿(A rtem isia ord osica)为研究对象,前者是典型的游击型克隆植物,后者是密集型克隆植物。采取野外调查的方式,观测在不同植被盖度的小生境斑块内二者地上生物量分配格局的变化情况,并结合二者的克隆构型和生活史特征试图探讨产生这种格局的原因。结果表明:羊柴的地上各部分生物量对植被盖度变化的响应不如油蒿敏感。这或者是因为羊柴的游击型克隆构型决定其可以跨越小尺度斑块实现克隆生理整合,可以利用不同小生境斑块的资源导致的。油蒿只能利用小生境斑块内的资源,当小生境斑块的条件改变,其生物量以及配置方式也随之发生相应的变化。在繁殖方式上,羊柴的有性繁殖结构以及有性繁殖投资显著小于油蒿。在资源有限的条件下,对一种繁殖方式的投资常常会削弱另一种繁殖方式。羊柴主要依靠克隆繁殖,这或者符合并支持配置理论的观点。  相似文献   

7.
This study evaluated the discriminant capability of stability measures, trunk kinematics, and step kinematics to classify successful and failed compensatory stepping responses. In addition, the shared variance between stability measures, step kinematics, and trunk kinematics is reported. The stability measures included the anteroposterior distance (d) between the body center of mass and the stepping limb toe, the margin of stability (MOS), as well as time-to-boundary considering velocity (TTB(v)), velocity and acceleration (TTB(a)), and MOS (TTB(MOS)). Kinematic measures included trunk flexion angle and angular velocity, step length, and the time after disturbance onset of recovery step completion. Fourteen young adults stood on a treadmill that delivered surface accelerations necessitating multiple forward compensatory steps. Thirteen subjects fell from an initial disturbance, but recovered from a second, identical disturbance. Trunk flexion velocity at completion of the first recovery step and trunk flexion angle at completion of the second step had the greatest overall classification of all measures (92.3%). TTB(v) and TTB(a) at completion of both steps had the greatest classification accuracy of all stability measures (80.8%). The length of the first recovery step (r ≤ 0.70) and trunk flexion angle at completion of the second recovery step (r ≤ -0.54) had the largest correlations with stability measures. Although TTB(v) and TTB(a) demonstrated somewhat smaller discriminant capabilities than trunk kinematics, the small correlations between these stability measures and trunk kinematics (|r| ≤ 0.52) suggest that they reflect two important, yet different, aspects of a compensatory stepping response.  相似文献   

8.
Phospholipase A(2) (PLA(2)) quantitation in real-time, using (7-nitro-2-1,3-benzoxadiazol-4-yl)amino-derivatives of phosphatidylcholine (NBD-PCs) as substrates, is influenced by high protein content, color or turbidity. The purpose of the study was to overcome such limitations by a complementary reversed-phase HPLC step to separate the substrates from the products of the reaction. Plasma and bronchoalveolar lavage (BAL) fluid were applied as enzymic sources, while standard porcine PLA(2) and human plasma PAF-acetylhydrolase (PAF-AH) were employed as positive controls. The method was validated with a radiometric assay and compared with the real-time fluorimetric assay. Regarding PLA(2) and PAF-AH determination, the isocratic elution systems CH(3)OH-H(2)O (80:20, v/v) and CH(3)OH-H(2)O-CH(3)COOH (60:40:0.2, v/v/v) separated efficiently C(12)-NBD-FA/C(12)-NBD-PC and C(6)-NBD-FA/C(6)-NBD-PC, with 4.4 and 2.2 resolution, respectively. Analysis time was ~15 min/injection. The reproducibility, expressed as relative standard deviation, was ≤13% for PLA(2) and ≤16% for PAF-AH, respectively. The assay was linear for PLA(2) activities extending from 1 pmol up to at least 250 nmol FA/h/mL sample, similar to the radiometric assay. It was appropriate for samples with high protein content, where the real-time fluorimetric assay was insufficient. The HPLC method was also evaluated under elevated temperatures, various pH values and Ca(2+) concentrations.  相似文献   

9.
This study examined the effect of friction between the hand and grip surface on a person's grip strategy and force generation capacity. Twelve young healthy adults performed power grip exertions on an instrumented vertical cylinder with the maximum and 50% of maximum efforts (far above the grip force required to hold the cylinder), while normal and shear forces at each phalanx of all five fingers in the direction orthogonal to the gravity were recorded. The cylinder surface was varied for high-friction rubber and low-friction paper coverings. An increase in surface friction by replacing the paper covering with the rubber covering resulted in 4% greater mean phalanx normal force (perpendicular to the cylinder surface) and 22% greater mean phalanx shear force in either the proximal or distal direction of the digits (p<0.05; for both 50% and maximum grip efforts). Consequently, increased friction with the rubber surface compared to the paper surface was associated with a 20% increase in the angular deviation of the phalanx force from the direction normal to the cylinder surface (p<0.05). This study demonstrates that people significantly changed the magnitude and direction of phalanx forces depending on the surface they gripped. Such change in the grip strategy appears to help increase grip force generation capacity. This finding suggests that a seemingly simple power grip exertion involves sensory feedback-based motor control, and that people's power grip capacity may be reduced in cases of numbness, glove use, or injuries resulting in reduced sensation.  相似文献   

10.
The human distal thumb phalanx from the earlier Upper Paleolithic of Ob?azowa Cave, southern Poland, exhibits features of its palmar surface that align it morphologically principally with early modern humans. These aspects include the configurations of the proximal palmar fossa, the flexor pollicis longus tendon insertion, the proximal margin of the palmar apical tuft, and especially its low ulnar deviation angle. If it is assumed that it possessed the pollical phalangeal length proportions of an early modern human, it would exhibit modest base and tuft breadths. However, given Late Pleistocene archaic-modern contrasts in relative pollical phalanx lengths, the isolated nature of the phalanx prevents secure assessment of its radioulnar interphalangeal articular and apical tuft hypertrophy. Similar constraints apply to the assessment of other Pleistocene Homo pollical phalanges.  相似文献   

11.
 采用样线法和点样法对鄂尔多斯风蚀沙化梁地上的植物进行了调查,研究了梁地上克隆植物的分布、克隆植物在群落中的重要性及其与群落物种多样性之间的关系。结果表明:1)在梁顶的典型草原植物群落和梁底的滩地盐生植物群落中克隆植物的物种丰富度较高,而在梁坡的沙生植物群落中较少,非克隆植物物种在梁顶出现频率较高,在梁坡和梁底较少;密集型克隆植物物种丰富度的变化与非克隆植物相同,游击型克隆植物在梁顶植物群落中没有出现,在梁坡群落中也很少,而在梁底的滩地中较多。2)梁底群落中克隆植物的重要值高于梁顶和梁坡群落中克隆植物的重要值,梁顶与梁坡群落中非克隆植物的重要值高于梁底群落中非克隆植物的重要值;在梁坡与梁底群落中,克隆植物的重要值都高于非克隆植物的重要值,而在梁顶群落中克隆植物与非克隆植物的重要值之间无差异;梁顶与梁坡群落中密集型克隆植物的重要值高于梁底群落中密集型克隆植物的重要值,而游击型克隆植物的重要值在梁底群落中较高;在梁顶与梁坡群落中,密集型克隆植物的重要值分别高于游击型克隆植物的重要值,而在梁底群落中,密集型克隆植物的重要值低于游击型克隆植物的重要值。3)梁顶的典型草原植物群落中,群落物种多样性随非克隆植物的重要值、克隆植物的重要值、密集型克隆植物的重要值的变化趋势相同,都为抛物线型。梁坡的沙生植物群落中,群落物种多样性与非克隆植物的重要值呈正相关,而分别与克隆植物和密集型克隆植物的重要值呈负相关。梁底的滩地盐生植物群落中,群落物种多样性与非克隆植物的重要值呈正相关,而与克隆植物和游击型克隆植物的重要值呈负相关。  相似文献   

12.
All carnivorans retract and protract their claws. In felids and some viverrids the claws of digits II through V of both the manus and pes have a larger arc of rotation than those of other carnivorans; the claws retract to the lateral side of the middle phalanx rather than onto its dorsal surface as in most other carnivorans. This condition should be termed hyper-retraction. Morphological features of the middle and distal (ungual) phalanges that have been purported to be necessary for hyper-retraction in felids vary considerably among digits within the manus and pes. These features include the lateral projection of the distal head and the asymmetry of the shaft of the middle phalanx, and the oblique orientation of the articular surface on the distal phalanx. None of these features is necessary in every instance for hyperretraction, and some of the variation in these features is associated instead with protraction. Differences among digits in the orientation of the articular surface on the distal phalanx are associated with differences in the degree to which the claws must move laterally to rotate from the protracted to the retracted position. Differences in the orientation of the distal head on the middle phalanx are associated with the spreading of the claws during protraction. The manual claws are hook-shaped, whereas the pedal claws are more blade-like; this morphological difference is associated with differences in function between the manus and pes. In the manus the medial claws have a larger radius of curvature and a smaller angle of arc as compared to the more lateral claws; in the pes, the claws on digits III and IV have larger radii of curvature and smaller angles of arc. Digit I of the manus lacks the hyper-retraction mechanism; nonetheless, this digit shares many of the attributes that are associated with this mechanism. © 1996 Wiley-Liss, Inc.  相似文献   

13.
Examination of the water mite collection made by the authors in the territory of the Sakha Republic (Yakutia) in 2006 has revealed 43 mite species of the phalanx Hydrachnidia, belonging to 19 genera and 12 families, 1 species of the phalanx Trombidia, and 2 freshwater species of the superfamily Halacaroidea, belonging to 2 genera and 1 family. All the species registered, except for two species of the phalanx Hydrachnidia (Mixobates processifer and Lebertia porosa), were recorded in the Sakha Republic for the first time. The species Aturus miyashitai Uchida, 1934 and A. parapilosus Kim et Chung, 1993 (Hydrachnidia) and the family Johnstonianidae Thor, 1935 (Trombidia) are new for the Russian fauna. The female of A. parapilosus is described for the first time.  相似文献   

14.
A high-performance liquid chromatographic (HPLC) method was developed for the combined analysis of the chemoprotective agent, amifostine, its active metabolite, WR 1065, and the (symmetrical and mixed) disulfides of WR 1065 in plasma. These three compounds were quantified by measuring WR 1065 after three different sample pretreatment procedures. During these procedures, amifostine and the disulfides were quantitatively converted into WR 1065, by incubating the sample either at a low pH or in the presence of dithiothreitol, respectively. The resulting amounts of WR 1065 were determined by HPLC with electrochemical detection (Au electrode, +1.00 V). The lower limit of quantitation of WR 1065 was 0.15 μM. The within-day and between-day precision were ≤4.4 and ≤8.2% for WR 1065, ≤4.9 and ≤13.1% for amifostine and ≤8.5 and ≤5.5% for the disulfides, respectively. The within-day and between-day accuracy ranged from 97.2 to 109.8% and from 97.6 to 101.5% for WR 1065, from 88.3 to 110.7% and from 99.4 to 101.5% for amifostine and from 99.2 to 110.2% and from 103.3 to 104.9% for the disulfides, respectively. This method is superior to other described methods due to its simple and relatively rapid analysis of all three compounds in one system. Furthermore, it is at least as sensitive as earlier reported methods for one of the compounds and the application of the gold electrode requires only minor maintenance. Therefore, this method is very suitable for pharmacokinetic studies of amifostine and its metabolites. As an example, the plasma concentrations of amifostine, WR 1065 and the disulfides are shown in a patient after receiving an i.v. dose of 740 mg/m2 amifostine.  相似文献   

15.
The growth form along the continuum from compact phalanx plants to more loosely packed guerilla plants is an important life-history trait in clonal plants. Prerequisite for its evolution is heritable genetic variation. Starting with 102 genotypes of the stoloniferous herb Ranunculus reptans, we performed one selection experiment on spatial spread per rosette as measure of guerillaness (broad-sense heritability 0.198) and another on plasticity in this trait in response to competition (broad-sense heritability 0.067). After two generations, spatial spread was 36.9% higher in the high line than in the low line (realized heritability +/- SE 0.149 +/- 0.039). Moreover, compared with the low line genotypes of the high line had fewer rosettes, a lower proportion of flowering rosettes, a higher proportion of rooted rosettes, more branches per rosette, longer internodes and longer leaves. In the second experiment, we found no significant direct response to selection for high and low plasticity in spatial spread (realized heritability +/- SE -0.029 +/- 0.063), despite a significant correlated response in plasticity in the length of the first three stolon internodes. Our study indicates a high potential for further evolution of the clonal growth form in R. reptans, but not for its plasticity, and it demonstrates that the clonal growth form does not evolve independently of other clonal life-history characteristics.  相似文献   

16.
Vertebrate claws are used in a variety of important behaviours and are typically composed of a keratinous sheath overlying the terminal phalanx of a digit. Keratinous claws, however, are rare in living amphibians; their microstructure and other features indicate that they probably originated independently from those in amniotes. Here we show that certain African frogs have a different type of claw, used in defence, that is unique in design among living vertebrates and lacks a keratinous covering. These frogs have sectorial terminal phalanges on their hind feet that become functional by cutting through the skin. In the resting state, the phalanx is subdermal and attached to a distal bony nodule, a neomorphic skeletal element, via collagen-rich connective tissue. When erected, the claw breaks free from the nodule and pierces the ventral skin. The nodule, suspended by a sheath attached to the terminal phalanx and supported by collagenous connections to the dermis, remains fixed in place. While superficially resembling the shape of claws in other tetrapods, these are the only vertebrate claws known to pierce their way to functionality.  相似文献   

17.
Ongoing excavations in the Middle Paleolithic levels at the Gruta da Oliveira, Portugal have yielded four fragmentary human remains, a manual phalanx and an ulna from levels 9 and 10, and a humerus and a tibia from levels 18 and 19. The first two remains date to approximately 39 ka 14C BP ( approximately 43.5 ka cal BP), whereas the latter two derive from earlier in oxygen isotope stage 3. The preserved portions of the phalanx, humerus, and tibia align them morphologically with the Neandertals. In addition, the Oliveira 4 tibial diaphysis shows evidence of carnivore (probably canid) gnawing.  相似文献   

18.
Biomechanics of phalangeal curvature   总被引:1,自引:0,他引:1  
Phalangeal curvature has been widely cited in primate functional morphology and is one of the key traits in the ongoing debate about whether the locomotion of early hominins included a significant degree of arboreality. This study examines the biomechanics of phalangeal curvature using data on hand posture, muscle recruitment, and anatomical moment arms to develop a finite element (FE) model of a siamang manual proximal phalanx during suspensory grasping. Strain patterns from experiments on intact cadaver forelimbs validated the model. The strain distribution in the curved siamang phalanx FE model was compared to that in a mathematically straight rendition in order to test the hypotheses that curvature: 1) reduces strain and 2) results in lower bending strains but relatively higher compression. In the suspensory posture, joint reaction forces load the articular ends of the phalanx in compression and dorsally, while muscle forces acting through the flexor sheath pull the mid-shaft palmarly. These forces compress the phalanx dorsally and tense it palmarly, effectively bending it 'open.' Strains in the curved model were roughly half that of the straight model despite equivalent lengths, areas, mechanical properties, and loading conditions in the two models. The curved model also experienced a higher ratio of compressive to tensile strains. Curvature reduces strains during grasping hand postures because the curved bone is more closely aligned with the joint reaction forces. Therefore, phalangeal curvature reduces the strains associated with arboreal, and especially suspensory, activity involving flexed digits. These results offer a biomechanical explanation for the observed association between phalangeal curvature and arboreality.  相似文献   

19.
A sensitive and precise LC-ESI-MS/MS method for the determination of vandetanib (ZD6474) in human plasma and cerebrospinal fluid (CSF) using [(13)C,d(3)]-ZD6474 as an internal standard (ISTD) was developed and validated. Sample preparation consisted of a simple liquid-liquid extraction with tert-butyl methyl ether containing 0.1% or 0.5% ammonium hydroxide. ZD6474 and ISTD were separated on a Kinetex C18 column (2.6 μm, 50 mm × 2.1 mm) at ambient temperature with an isocratic mobile phase (acetonitrile/10mM ammonium formate=50/50, v/v, at pH 5.0) delivered at 0.11 mL/min. The retention time of both compounds was at 1.60 min in a runtime of three min. Detection was achieved by an API-3200 LC-MS/MS system, monitoring m/z 475.1/112.1 and m/z 479.1/116.2 for vandetanib and ISTD, respectively. The method was linear in the range of 0.25-50 ng/mL (R(2) ≥ 0.990) for the CSF curve and from 1.0 to 3000 ng/mL (R(2) ≥ 0.992) for the plasma curve. The mean recovery for vandetanib was 80%. Within-day and between-day precisions were ≤ 8.8% and ≤ 5.9% for CSF and plasma, respectively. Within-day and between-day accuracies ranged from 95.0 to 98.5% for CSF, and from 104.0 to 108.5% for plasma. Analysis of plasma from six different sources showed no matrix effect for vandetanib (MF=0.98, %CV ≤ 4.97, n=6). This method was successfully applied to the analysis of pharmacokinetic samples from children with brain tumors treated with oral vandetanib.  相似文献   

20.
This work aimed to develop a chiral separation method of ketoconazole enantiomers using electrokinetic chromatography. The separation was achieved using heptakis (2, 3, 6‐tri‐O‐methyl)‐β‐cyclodextrin (TMβCD), a commonly used chiral selector (CS), as it is relatively inexpensive and has a low UV absorbance in addition to an anionic surfactant, sodium dodecyl sulfate (SDS). The influence of TMβCD concentration, phosphate buffer concentration, SDS concentration, buffer pH, and applied voltage were investigated. The optimum conditions for chiral separation of ketoconazole was achieved using 10 mM phosphate buffer at pH 2.5 containing 20 mM TMβCD, 5 mM SDS, and 1.0% (v/v) methanol with an applied voltage of 25 kV at 25 °C with a 5‐s injection time (hydrodynamic injection). The four ketoconazole stereoisomers were successfully resolved for the first time within 17 min (total analysis time was 28 min including capillary conditioning). The migration time precision of this method was examined to give repeatability and reproducibility with RSDs ≤5.80% (n =3) and RSDs ≤8.88% (n =9), respectively. Chirality 27:223–227, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   

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