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991.
992.
993.
Neuronal nuclear antigen (NeuN), discovered in mice brain cell nuclei by Mullen et al. (1992), is used as an excellent marker of post-mitotic neurons in vertebrates. In this study, the expression pattern of NeuN was examined in the Xenopus brain to explore phylogenetic differences in NeuN expression. Anti-NeuN antibody showed selective staining in mouse and Xenopus brain extracts, but the number and molecular weight of the bands differed in Western blotting analysis. In immunostaining, anti-NeuN antibody showed selective staining of neurons, but not glial cells, in the Xenopus brain. Most neurons, including olfactory bulb mitral cells and cerebellar Purkinjie cells, which show no immunoreactivity in birds/mammals, showed NeuN immunoreactivity in Xenopus. This study revealed that anti-NeuN antibody is a useful marker of post-mitotic neurons in amphibians, but it also stains neurons that show no reactivity in more derived animals. 相似文献
994.
Fibroblast growth factor-2 immunoreactivity is present in the central and peripheral auditory pathways of adult rats 总被引:2,自引:0,他引:2
Recent findings have pointed out the role of neurotrophic factors in the survival and maintenance of neurons of the auditory system. Basic fibroblast growth factor (bFGF, FGF-2) is a potent neurotrophic molecule whose actions can be seen in the central and peripheral nervous systems. In the present study, FGF-2 immunoreactivity was analyzed in the auditory pathways of the adult rat, employing a well-characterized polyclonal antibody against FGF-2. In the cochlea, FGF-2 immunoreactivity was observed in the inner and outer hair cells of the organ of Corti, spiral ganglion neurons, spiral limbus, and stria vascularis. Stereological methods employing optical fractionator revealed the presence of 84.5, 15, and 0.5% of spiral ganglion neurons possessing FGF-2 immunoreactivity of strong, moderate, and weak intensity, respectively. In the central auditory pathways, FGF-2 immunoreactivity was found in the cytoplasm of the neurons of the cochlear nuclei, trapezoid body nuclei, medial geniculate nucleus, and inferior colliculus. The two-color immunoperoxidase method showed FGF-2 immunoreactivity in the nuclei of astrocytes throughout the central auditory pathway. Computer-assisted microdensitometric image analysis revealed higher levels of specific mean gray values of FGF-2 immunoreactivity in the trapezoid body and ventral cochlear nucleus and also in the spiral ganglion and inner hair cells. Sections incubated with FGF-2 antibody preabsorbed with human recombinant FGF-2 showed no immunoreaction in the majority of the studied regions, exhibiting only a slight immunoreactive product in the hair cells of the organ of Corti. Furthermore, no changes in immunoreactivity were observed in sections incubated with FGF-2 antiserum preincubated with human recombinant acidic FGF (FGF-1). The findings suggest that FGF-2 may exert paracrine and autocrine actions on neurons of the central and peripheral auditory systems and may be of importance in the mechanism of hearing diseases. 相似文献
995.
Using the combined Golgi-electron microscopy technique, we have determined the three-dimensional dendritic fields of the short
visual fibres (svf 1–3) and first-order interneurons or L-fibres (L1-4) within the first optic ganglion (lamina) of the nocturnal
bee Megalopta genalis. Serial cross sections have revealed that the svf type 2 branches into one adjacent neural unit (cartridge) in layer A, the
most distal of the three lamina layers A, B and C. All L-fibres, except L1-a, exhibit wide lateral branching into several
neighbouring cartridges. L1-b shows a dendritic field of seven cartridges in layers A and C, dendrites of L2 target 13 cartridges
in layer A, L3 branches over a total of 12 cartridges in layer A and three in layer C and L4 has the largest dendritic field
size of 18 cartridges in layer C. The number of cartridges reached by the respective L-fibres is distinctly greater in the
nocturnal bee than in the worker honeybee and is larger than could be estimated from our previous Golgi-light microscopy study.
The extreme dorso-ventrally oriented dendritic field of L4 in M. genalis may, in addition to its potential role in spatial summation, be involved in edge detection. Thus, we have shown that the
amount of lateral spreading present in the lamina provides the anatomical basis for the required spatial summation. Theoretical
and future physiological work should further elucidate the roles that this lateral spreading plays to improve dim-light vision
in nocturnal insects.
B.G. is grateful for grants from the Royal Physiographic Society, the Per Westlings Fond, the Foundation of Dagny and Eilert
Ekvall and the Royal Swedish Academy of Sciences. E.J.W. would like to thank the Smithsonian Tropical Research Insitute, the
Swedish Research Council, the Crafoord Foundation, the Wenner-Gren Foundation and the Royal Physiographic Society of Lund
for their ongoing support. 相似文献
996.
997.
Ito M 《Biochemical and biophysical research communications》2003,301(2):564-571
Treatment of RGCs with insulin or C2 ceramide alone increased survival rate by 30%. Adding both insulin and C2 ceramide increased survival rate by 80%. Protein phosphatase 2A (PP2A) inhibitor okadaic acid (OA) eliminated the effect of C2 ceramide, but not that of insulin. Protein kinase inhibitor K252a decreased the effect of C2 ceramide in a dose-dependent manner, but the effect of insulin was not changed. Treatment of RGCs with bFGF increased survival rate by 36%. Adding both bFGF and C2 ceramide increased survival rate by 102%. OA did not alter the effect of bFGF, whereas K252a increased survival rate in a dose-dependent manner. Inhibition of C2 ceramide by OA suggests that PP2A activation is involved in its pathway, whereas PP2A is not involved in the insulin- and bFGF-activated pathway. Elimination of the effect of C2 ceramide by K252a suggests that sphingomyelin cycle activation is mediated by a protein kinase not important in the insulin-activated pathway. Moreover, the increased effect of bFGF and dose-dependently decreased effect of C2 ceramide by K252a suggest that different protein kinases are important in bFGF- and ceramide-mediated enhancement of RGC survival rate. 相似文献
998.
Leptin increases human alpha1 (I) collagen mRNA and type I collagen production and enhances hepatic fibrosis in animal models of hepatic fibrosis. These effects of leptin on fibrogenesis may be mediated by TGFbeta1, since leptin increases the TGFbeta type II receptor and augments the effect of TGFbeta1 on collagen production by stellate cells. In this study, leptin increased the activity of the human alpha1 (I) collagen promoter in transfected stellate cells. Leptin did not further enhance the activation of the promoter induced by TGFbeta1. Leptin had no effects on the transfected TGFbeta-responsive p3TP-LUX plasmid, which contains 3 CAGA elements that are essential and sufficient for the induction by TGFbeta. Leptin did not increase significantly the binding of proteins to two TGFbeta1 responsive elements in the human alpha1 (I) collagen promoter. In conclusion, this study shows that leptin activates the alpha1 (I) collagen gene and that this effect is not mediated by TGFbeta responsive elements. 相似文献
999.
腺病毒介导的NT3基因转染对噪音损伤的耳蜗螺旋神经节细胞的保护作用 总被引:23,自引:0,他引:23
神经营养素 3(neurotrophin 3,NT3)作为螺旋神经节细胞特异的营养因子 ,可有效地支持内耳传入神经元的存活 ,因此有望成为治疗因其退变而引起的感音性神经性耳聋的有效因子。实验采用腺病毒介导lacZ基因 ,检测了外源基因在豚鼠内耳中的长期表达。用噪音制备了豚鼠耳聋模型 ,在噪音损伤后第 7天 ,通过圆窗膜注入 1× 10 8重组腺病毒。注入神经营养素 3重组腺 (Ad NT3)的组为实验组 ,注入Ad lacZ的为对照组。 4周后 ,经NT3抗体免疫细胞化学染色可见 ,在注入Ad NT3病毒的实验组中 ,在内耳多种细胞中有明显的NT3蛋白的表达。HE染色显示 ,注射Ad lacZ组的豚鼠耳蜗螺旋神经节细胞明显退变 ,螺旋神经节内细胞间隙拉大 ,细胞密度明显低于注射Ad NT3实验组动物 (P <0 .0 1)。这一结果说明 ,腺病毒介导的NT3基因可长期表达于内耳中 ,并且可在噪音引起毛细胞死亡后有效地抑制螺旋神经节细胞的退变。 相似文献
1000.
Peripherin is a type III intermediate filament (IF) abundantly expressed in developing neurons, but in the adult, it is primarily found in neurons extending to the peripheral nervous system. It has been suggested that peripherin may play a role in axonal elongation and/or cytoskeletal stabilization during development and regeneration. To further clarify the function of peripherin, we generated and characterized mice with a targeted disruption of the peripherin gene. The peripherin null mice were viable, reproduced normally and did not exhibit overt phenotypes. Microscopic analysis revealed no gross morphological defects in the ventral and dorsal roots, spinal cord, retina and gut, but protein analyses showed increased levels of the type IV IF alpha-internexin in ventral roots of peripherin null mice. Whereas the number and caliber of myelinated motor and sensory axons in the L5 roots remained unchanged in peripherin knockout mice, there was a substantial reduction ( approximately 34%) in the number of L5 unmyelinated sensory fibers that correlated with a decreased binding of the lectin IB4. These results demonstrate a requirement of peripherin for the proper development of a subset of sensory neurons. 相似文献