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排序方式: 共有158条查询结果,搜索用时 359 毫秒
1.
犬脑11只,经生理盐水冲洗脑血管后,注入20%钡胶液,切成0.2~1.0厘米的厚片,用显微X线法研究犬脑内各级动脉的构筑,其结果:1.皮质动脉的管径平均为25.9±0.005微米,平均长度为888.0±0.241微米。其形态与发出部位有关,分别呈栅状和瓶刷状。2.髓质动脉的管径平均为49.9±0.007微米。呈直线或孤形向心走行。3.皮质下动脉的管径平均为38.7±0.009微米。呈新月形或蟹钳状分布。4.豆纹动脉和内囊动脉的平均管径为70.0±0.021微米。呈锐角、反血流方向发自母干,再呈“S”形上升。5.丘脑动脉的平均管径为63.7±0.019微米,主要从下方进丘脑,呈树枝状分支。 相似文献
2.
The morphology,innervation and neural control of the anterior arterial system of Aplysia californica
M. E. Skelton J. Koester 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,171(2):141-155
Summary The morphology, innervation, and neural control of the anterior arterial system of Aplysia californica were investigated. Immunocytochemical and histochemical techniques generated positive reactions in the anterior arterial system for several neuroactive substances, including SCPB, FMRFamide, R151 peptide, dopamine and serotonin. Three neurons were found to innervate the rostral portions of the anterior arterial tree. One is the identified peptidergic neuron R15 in the abdominal ganglion, and the other two are a pair of previously unidentified neurons, one in each pedal ganglion, named pedal arterial shorteners (PAS)- The endogeneously bursting neuron R15 was found to innervate the proximal anterior aorta. It also innervates a branch of the distal anterior aorta, the left pedal-parapodial artery. Activity in R15 causes constriction of the left pedal-parapodial artery. This effect is presumed to direct hemolymph towards the genital groove and penis on the right side in vivo. This vasoconstrictor action of R15 is mimicked by the R151 peptide. The PAS neuron pair causes longitudinal contraction of the rostral anterior aorta and the pedal-parapodial arteries. In vivo, the pair is active during behaviors involving head withdrawal and turning. By adjusting the length of the arteries during postural changes, the PAS neurons may prevent disturbances in blood flow due to bending or kinking of the arterial walls. 相似文献
3.
Gianni Pedrizzetti Luigino Zovatto Federico Domenichini Angela Tortoriello 《Computer methods in biomechanics and biomedical engineering》2013,16(3):219-231
Pulsatile flow inside a moderately elastic circular conduit with a smooth expansion is studied as a model to understand the influence of wall elasticity in artery flow. The solution of the simultaneous fluid-wall evolution is evaluated by a perturbative method, where the zeroth order solution is represented by the flow in a rigid vessel; the first order correction gives the wall motion and induced flow modification without the need to solve the difficult coupled problem. Such an approach essentially assumes a locally infinite celerity, therefore it represent a good approximation for the fluid-wall interaction in sites of limited extent (branches, stenosis, aneurism, etc.), which include typical situations associated with vascular diseases. The problem is solved numerically in the axisymmetric approximation; the influence of wall elasticity on the flow and on the unsteady wall shear stress is studied in correspondence of parameters taken from realistic artery flow. Attention is posed to the role of phase difference between the incoming pressure and flow pulses. 相似文献
4.
目的:探讨丹皮酚(Paeonol,Pae)对血管紧张素II(AngiotensinⅡ,AngⅡ)所致动脉内皮功能障碍的保护作用及其机制。方法:采用实时定量聚合酶链式反应(RT-PCR)和Westernblot检测酸性鞘磷脂酶(acidsphingomyelinase,ASM)基因及蛋白表达;采用免疫组织荧光检测血管环神经酰胺(ceramide,Cer)含量变化;采用血管环张力描记技术检测主动脉血管环的舒张功能;采用二氢乙啶荧光探针(dihydroethidium,DHE)检测血管环超氧阴离子(superoxideanion,O2-·)水平。结果:与对照组相比,AngⅡ孵育后主动脉对乙酰胆碱(acetylcholine,Ach)的舒张反应显著降低,Pae与AngⅡ共孵育则无明显改变;AngⅡ及Pae孵育后,动脉对硝普钠(sodiumnitroprusside,SNP)的舒张反应均无明显变化;AngⅡ孵育可增高动脉环O2-·水平,这一反应被Pae明显抑制;与对照组相比,AngⅡ孵育动脉ASMmRNA水平无明显改变,但蛋白表达显著增加,Cer含量显著增多,Pae与AngⅡ共孵育动脉ASM蛋白及Cer水平与对照组相比均无明显改变;采用神经酰胺酶抑制剂N-oleoylethanolamine(OEA)增加动脉Cer含量后,Pae降低动脉O2-·水平以及增强Ach舒张反应的效应被显著抑制。结论:Pae通过ASM/Cer通路改善AngⅡ所致动脉氧化应激增强和内皮功能障碍。 相似文献
5.
韩力 《现代生物医学进展》2007,7(10):1548-1549
目的:探讨平板运动试验(TET)对诊断冠状动脉粥样硬化性心脏病(冠心病)的临床意义。方法:对比分析217例疑诊或临床诊断冠心病患者的平板运动试验和选择性冠状动脉造影(CAG)结果。结果:以选择性冠状动脉造影为标准,平板运动试验敏感性为68.4%,特异性为88.4%,阳性预测值为77.1%,阴性预测值为82.9%。结论:简便、易行及无创的平板运动试验是诊断冠心病的重要手段。 相似文献
6.
Paul B Green 《American journal of botany》1999,86(8):1059-1076
Pattern formation in plant meristems occurs across a broad scale. At the topographical level (large scale), tissue folding in the meristem is responsible for the initiation of new organs in specific phyllotactic patterns and also determines organ shape. At the cellular level (small scale), oriented cell division and microtubule-based cellulose reinforcement control cell pattern and growth direction. I argue here that structural specification at each scale is highly efficient if the pertinent gene activity is manifested in two complementary biophysical categories. At large scale, one category is the tendency of the formative tissue to fold with a certain spatial periodicity determined by its material properties (e.g., bending stiffness from cellulose content). This latent tendency is formalized in a differential equation for physical buckling. The second category at this scale comprises boundary conditions that specify how the latent tendency is manifested as topography: whether tissue humps occur as whorls or Fibonacci spirals. This versatile combinatorial format accounts for the relative stability of alternative organ patterning as well as alternative organ shaping (e.g., stamens vs. carpels). It also accounts for the structural shifts seen in normal development and after mutation or chemical/physical intervention. At small scale, the latent differential activity is the tendency for groups of dividing cells to co-align their cytoskeletons. The curvature of the surface opposes this tendency. The least curved part of a new primordium is its quasicylindrical midportion. There, by aligning microtubules and cellulose coherently around the organ, a new growth direction is set. Thus large-scale buckling produces curvature variation, which, in turn, affects the localization and orientation of the cytoskeleton. This scheme for the coherent production of diverse geometrical features, involving calculus at two structural levels, is supported by complex organogenetic responses to simple physical intervention. Also, many morphological alternatives, wild type vs. mutant, reflect single changes in parameters in this differential-integral format. 相似文献
7.
Naganuma T Tohno Y Yamasaki M Tohno S Azuma C Minami T Morikawa H 《Biological trace element research》2004,101(3):203-210
To elucidate compositional changes of the rami of the internal iliac artery with aging, the authors investigated age-related
changes of the calcium content in the uterine, internal pudendal, umbilical, and obturator arteries by inductively coupled
plasma-atomic emission spectrometry. After an ordinary dissection was finished, the uterine, internal pudendal, umbilical,
and obturator arteries were resected from 10 female subjects, and the internal pudendal, umbilical, and obturator arteries
were resected from 10 male subjects. The female subjects ranged in age from 52 to 96 yr, and the male subjects ranged in age
from 63 to 88 yr. The calcium content in the uterine artery began to increase in the seventies and increased markedly in the
nineties. In the internal pudendal artery, the calcium content hardly increased up to the eighties and increased significantly
in the nineties. In contrast, the calcium content did not change in both the umbilical and obturator arteries with advancing
age. It was found that the average content of calcium was the highest in the uterine artery and decreased in the order internal
pudendal, umbilical, and obturator arteries. The average content of calcium in the uterine arteries corresponded to 46-fold
the amount of the women's obturartor arteries, in which it was the lowest. In the cases of men, the average content of calcium
was higher in the order of the internal pudendal, umbilical, and obturator arteries. Regarding the average content of calcium,
the order internal pudendal, umbilical, and obturator arteries of the men was consistent with that of the women. 相似文献
8.
Mahakkanukrauh P Tohno S Tohno Y Chomsung R Azuma C Moriwake Y Minami T 《Biological trace element research》2004,100(3):205-214
To examine whether there were differences between races in regard to the relationships among element contents in the arteries,
the authors investigated the relationships among the average contents of calcium, phosphorus, sulfur, and magnesium in the
18 kinds of the Thai artery. After ordinary dissection by medical students at Chiang Mai University was finished, the thoracic
and abdominal aortas, ramifying site of the abdominal aorta into the common iliac arteries, coronary, common carotid, internal
thoracic, subclavian, axillary, brachial, radial, superior and inferior mesenteric, renal, common iliac, internal iliac, and
external iliac arteries were resected from the subjects who consisted of 12 men and 3 women, ranging in age from 39 to 84
yr. The femoral and posterior tibial arteries were resected from the subjects, consisting of 15 men and 5 women, ranging in
age from 25 to 88 yr. The element content of the arteries was analyzed by inductively coupled plasma-atomic emission spectrometry.
It was found that there were extremely significant direct correlations among the average contents of calcium, phosphorus,
and magnesium in the 18 kinds of the Thai artery, but no significant correlations were found between the average contents
of sulfur and elements, such as calcium, phosphorus, and magnesium. These results were in agreement with those of the Japanese
arteries. Therefore, it was suggested that there was no significant difference between the arteries of the Thai and the Japanese
in the relationships among calcium, phosphorus, sulfur, and magnesium. 相似文献
9.
Abstract
The mechanism for initiation of lateral organs in the shoot apical meristem is still unknown. In this article we investigate
one critical component of a buckling mechanism of organ initiation (that is, the presence and distribution of compressive
stresses in the meristem). Direct evidence for compression in the sunflower capitulum was obtained from the gaping pattern
of shallow cuts and the propagation of fractures. Cuts gaped widely in the central region of the capitulum but remained closed,
or nearly so, in the generative and differentiation regions, suggesting the presence of circumferential compression at these
locations. Fractures were initiated in the generative region and propagated circumferentially over most of their length. They
did not cross the generative region perpendicularly, suggesting again the presence of compressive stresses in the circumferential
direction. This conclusion was confirmed by the stress distribution computed from the geometry of the capitulum at three stages
of development. One interpretation of these results is that the generative region corresponds to a zone of compression that
could control the initiation of new primordia by means of buckling of the tunica layer.
Received 12 January 2000; accepted 2 February 2000 相似文献
10.
The allometry of axis length, diameter, and taper is described for the trunk, rachis, and rachilla of nonbranching ramets of Aralia spinosa. Significant log-linear relationships were found between length and diameter for all axis categories, and in all cases, scaling was negatively allometric. Linear models best described the relationship between length and diameter for the rachis and rachilla, while a quadratic model best described this relationship for the trunk. During the trunk-building stage, the safety factors for trunk height were size dependent, with larger trunks exceeding their predicted critical buckling height. Taper was described by a linear relationship between diameter and position along the axis for all axis categories. All rachises and rachillas sampled exhibited taper along the length of the axis, however, only 51% of the trunks showed continuous taper. The trunk was less tapered than the rachis, but no differences in taper were found between the trunk and the rachilla, or the rachis and the rachilla. In unbranched ramets the large bipinnately compound leaves occupy the space normally occupied by lateral branches. We suggest that the rachis and rachilla are functionally equivalent to branches, that is, acting as axes of exploration and exploitation of the environment. 相似文献