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21.
22.
Morphological variation of layer III pyramidal neurones in the occipitotemporal pathway of the macaque monkey visual cortex 总被引:5,自引:5,他引:0
We compared the morphological characteristics of layer III pyramidal
neurones in different visual areas of the occipitotemporal cortical
'stream', which processes information related to object recognition in the
visual field (including shape, colour and texture). Pyramidal cells were
intracellularly injected with Lucifer Yellow in cortical slices cut
tangential to the cortical layers, allowing quantitative comparisons of
dendritic field morphology, spine density and cell body size between the
blobs and interblobs of the primary visual area (V1), the interstripe
compartments of the second visual area (V2), the fourth visual area (V4)
and cytoarchitectonic area TEO. We found that the tangential dimension of
basal dendritic fields of layer III pyramidal neurones increases from
caudal to rostral visual areas in the occipitotemporal pathway, such that
TEO cells have, on average, dendritic fields spanning an area 5-6 times
larger than V1 cells. In addition, the data indicate that V1 cells located
within blobs have significantly larger dendritic fields than those of
interblob cells. Sholl analysis of dendritic fields demonstrated that
pyramidal cells in V4 and TEO are more complex (i.e. exhibit a larger
number of branches at comparable distances from the cell body) than cells
in V1 or V2. Moreover, this analysis demonstrated that the dendrites of
many cells in V1 cluster along specific axes, while this tendency is less
marked in extrastriate areas. Most notably, there is a relatively large
proportion of neurones with 'morphologically orientation-biased' dendritic
fields (i.e. branches tend to cluster along two diametrically opposed
directions from the cell body) in the interblobs in V1, as compared with
the blobs in V1 and extrastriate areas. Finally, counts of dendritic spines
along the length of basal dendrites revealed similar peak spine densities
in the blobs and the interblobs of V1 and in the V2 interstripes, but
markedly higher spine densities in V4 and TEO. Estimates of the number of
dendritic spines on the basal dendritic fields of layer III pyramidal cells
indicate that cells in V2 have on average twice as many spines as V1 cells,
that V4 cells have 3.8 times as many spines as V1 cells, and that TEO cells
have 7.5 times as many spines as V1 cells. These findings suggest the
possibility that the complex response properties of neurones in rostral
stations in the occipitotemporal pathway may, in part, be attributed to
their larger and more complex basal dendritic fields, and to the increase
in both number and density of spines on their basal dendrites.
相似文献
23.
24.
Scrotal masses with a uniformly hyperechoic pattern 总被引:3,自引:0,他引:3
25.
The structure of carboxypeptidase a, vi. Some results at 2.0-a resolution, and the complex with glycyl-tyrosine at 2.8-a resolution 下载免费PDF全文
26.
Anil Kumar Rai Saurabh Singh Vinay Kumaraswamy GN Khare Vinit Yadav Rakesh Agarwal 《Indian Journal of Orthopaedics》2011,45(6):508-513
Background:
The bipolar hip prostheses after some time functions as a unipolar device. There is a need to change the design of bipolar hip prostheses to make it function as a bipolar device over a prolonged period of time. A bicentric bipolar hip prosthesis was used as an implant for various conditions of the hip. We evaluated the movement of this newly developed prosthesis at the interprosthetic joint radiologically at periodic intervals.Materials and Methods:
Fifty two cases were operarted with the Bicentric bipolar prosthesis for indications like fracture neck of femur and various other diseases of the hip and were followed up with serial radiographs at periodic intervals to evaluate, what fraction of the total abduction at the hip was occurring at the interprosthetic joint.Results:
In cases of intracapsular fracture neck of femur, the percentage of total abduction occurring at the interprosthetic joint at 3 months follow-up was 33.74% (mean value of all the patients), which fell to 25.66% at 1.5 years. In indications for bipolar hemireplacement other than fracture neck of femur, the percentage of total abduction occurring at the interprosthetic joint at 3 months follow-up was 71.71% (mean value) and at 1.5 years it was 67.52%.Conclusion:
This study shows the relative preservation of inner bearing movement in the bipolar hip prosthesis with time probably due its refined design. Further refinements are needed to make the prosthesis work better in patients of intracapsular fracture neck femur. 相似文献27.
28.
ObjectiveTo determine the prevalence of Trichomonas vaginalis (T. vaginalis) in HIV/AIDS patients attending two different hospitals in southeast Nigeria.MethodsWe collected 970 urine samples from HIV/AIDS patients attending two different hospitals in southeast Nigeria. Samples were processed by microscopy and cultural methods.ResultsOut of the 970 screened, 355 (36.60%) were positive for T. vaginalis. Subjects with the least CD4+ count in the range of 40-140 cells/mL had the highest number of positive samples (180, 50.70%), while those in the range of 480-580 cells/mL had the least value (2, 0.56%). Those in the rural areas had a higher number of positive samples (155, 38.75%) than their urban counterparts (200, 35.09%) with respect to the total number examined in each group but this was not statistically significant (P>0.05). Out of the 355 positive cases, the university undergraduate students’ group had the highest percentage incidence of 53.00% followed by the low-income group with 47.08%.ConclusionsIt can be concluded that the occurrence of T. vaginalis increases with decrease in the CD4+ counts in HIV/AIDS patients in Nigeria. Since T. vaginalis may be an important cofactor in promoting the spread of HIV and, in some circumstances, may have a major impact on the epidemic dynamics of HIV, there is a need to take measures to check the spread of this parasitic infection. 相似文献
29.
The occipitoparietal pathway of the macaque monkey: comparison of pyramidal cell morphology in layer III of functionally related cortical visual areas 总被引:13,自引:12,他引:1
The dendritic morphology of pyramidal cells located at the base of layer
III in the primary visual area (V1), the second visual area (V2), the
middle temporal area (MT), the ventral portion of the lateral intraparietal
area (LIPv) and in the portion of cytoarchitectonic area 7a within the
anterior bank of the superior temporal sulcus was revealed by injecting
neurons with Lucifer Yellow in fixed, flattened slices of macaque monkey
visual cortex. These areas correspond to different levels of the
occipitoparietal cortical 'stream', which processes information related to
motion and spatial relationships in the visual field. The tissue was
immunocytochemically processed to obtain a light-stable diaminobenzidine
reaction product, revealing the dendritic morphology in fine detail.
Retrogradely labelled MT- projecting neurons in supragranular V1 (layer
IIIc of Hassler's nomenclature, corresponding to Brodmann's layer IVb) were
predominantly pyramidal, although many spiny multipolar (stellate) cells
were also found. The average basal dendritic field area of pyramidal
neurons in sublamina IIIc of V1 was significantly smaller than that in the
homologous layer of V2, within the cytochrome oxidase-rich thick stripes.
Furthermore, the average basal dendritic field areas of V1 and V2 pyramidal
neurons were significantly smaller than those of neurons in MT, LIPv and
area 7a. There was no difference in basal dendritic field area between
layer III pyramidal neurons in areas MT, LIPv and 7a. While the shape of
most basal dendritic fields was circularly symmetrical in the dimension
tangential to the cortical layers, there were significant biases in
complexity, with dendritic branches tending to cluster along particular
axes. Sholl analysis revealed that the dendritic fields of neurons in areas
MT, LIPv and 7a were significantly more complex (i.e. had a larger number
of branches) than those of V1 or V2 neurons. Analysis of basal dendritic
spine densities revealed regional variations along the dendrites, with peak
densities being observed 40-130 microns from the cell body, depending on
the visual area. The peak spine density of layer III pyramidal neurons in
V1 was lower than that observed in V2, MT or LIPv, which were all similar.
Pyramidal neurons in area 7a had the greatest peak spine density, which was
on average 1.7 times that found in V1. Calculations based on the average
spine density and number of dendritic branches at different distances from
the cell body demonstrated a serial increase in the total number of basal
dendritic spines per neuron at successive stations of the occipitoparietal
pathway. Our observations, comparing dendritic fields of neurons in the
homologous cortical layer at different levels of a physiologically defined
'stream', indicate changes in pyramidal cell morphology between
functionally related areas. The relatively large, complex, spine-dense
dendritic fields of layer III pyramidal cells in rostral areas of the
occipitoparietal pathway allow these cells to sample a greater number of
more diverse inputs in comparison with cells in 'lower' areas of the
proposed hierarchy.
相似文献
30.
GN Dalekos ; E Zervou ; F Karabini ; M Elisaf ; K Bourantas ; KC Siamopoulos 《Transfusion》1995,35(6):503-506
BACKGROUND: In addition to human immunodeficiency virus, human T- lymphotropic virus types I and II (HTLV-I/II) is prevalent among blood donors in the United States. In Greece, there are no epidemiologic data regarding the prevalence of HTLV-I/II among volunteer blood donors and high-risk groups. STUDY DESIGN AND METHODS: To determine the prevalence of HTLV-I/II infections in northwestern Greece, a seroepidemiologic study was conducted among volunteer blood donors, multiply transfused patients, heroin addicts, and chronic hemodialysis patients. The subjects were tested for serologic evidence of HTLV-I/II infection by enzyme immunoassays and specific protein immunoblot confirmatory test. RESULTS: None of the volunteer blood donors and heroin addicts had detectable antibodies to HTLV-I/II. Only 1 (1.45%) of the 69 multiply transfused patients had indeterminate results, while 2 (1.2%) of 163 hemodialysis patients were positive. CONCLUSION: In northwestern Greece, routine screening for HTLV-I and HTLV-II infections does not appear to be required. However, the finding of seropositivity among hemodialysis patients requires further evaluation of the origin of the infection, as its zero prevalence in this population seems to exclude transfusion transmission. 相似文献