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2.
The effects of various metal cations and pH on the adsorption of uranium(VI) on strongly acidic cation exchanger Amberlite IR-118H (AIR-118H) were studied. The metal cations suppress U(VI) adsorption differently depending on their ionic radii. Adsorption of U(VI) on AIR-118H peaks at pH 3.4, which was attributed to the occurrence of different forms of U(VI) at different pH values. The adsorption data were then processed using the Frumkin–Fowler–Guggenheim equation, and the standard free energy of adsorption was calculated. 相似文献
3.
在颈椎生物力学研究中,通过离体实验对颈椎内植入固定器的生物力学性能进行评价是国际上普遍采用并认可的方法.本研究利用多靶点三维运动跟踪系统和USB数据采集卡,以LabVIEW和Matlab为软件开发平台,构建了颈椎内植入固定器生物力学性能测试系统.测试参数包括三维运动角度范围(ROM)和压力载荷值.对颈椎模型的测试结果表明,本系统能有效地用于颈椎生物力学的离体实验测试. 相似文献
4.
Tadashi Yasuda Hirokazu Imai Yasushi Nakamoto Akira B. Miura Shiegki Inomata 《Virchows Archiv : an international journal of pathology》1992,421(4):297-303
Summary The pathogenesis of the nodular lesion in diabetic glomerulosclerosis is described in association with fibrils. Thirteen diabetic patients with glomerular nodular lesions and 9 diabetics without the nodules were examined by electron microscopy using periodic acid-thio-carbohydrazide-silver proteinate staining. In cases of nodular glomerulosclerosis, abundant fibrillar structures mixed with electron-dense material were detected within the nodule and the mesangial matrix. They were also occasionally observed along the subendothelial space of the glomerular capillary walls. On the cross-section, these fibrils, including the lucent periphery, were 34 nm wide. Immunohistologically, collagen V and collagen VI were detected in nodular lesions. In contrast, in cases of the diffuse type of glomerulosclerosis, the widened mesangium was composed of dense material, which resembled the original mesangial matrix. The above fibrils were not detected in the mesangium. These findings suggest that the accumulation of the peculiar fibrils in the glomerular mesangium is a major pathogenic factor in the formation of Kimmelstiel-Wilson nodules. 相似文献
5.
Ei Kawahara Yoshio Oda Shogo Katsuda Isao Nakanishi Kunihiko Aoyama Katsuro Tomita 《Virchows Archiv : an international journal of pathology》1991,419(5):373-380
Summary Thickened ligamenta flava obtained from 14 patients with spinal canal stenosis were examined with special reference to type VI collagen. The characteristic histological finding in the thickened area was rupture of normal elastic fibre meshwork with resultant fibrosis which usually appeared hyaline. Using an immunohistological method, collagen types VI, I and III were found to be present in the hyaline matrix. Ultrastructural study revealed many microfilamentous structures of type VI collagen admixed in loosely packed, banded collagen fibres. With differential salt precipitation of pepsin-extracted collagen the existence of type VI collagen was confirmed by SDS-polyacrylamide gel electrophoresis analysis and Western blotting analysis using anti-type VI collagen antibody. Quantification of type VI collagen in pepsin-extracted crude collagen samples by an inhibition enzyme-linked immunosorbent assay showed an increasing amount of type VI collagen in the thickened ligamenta flava compared to the normal ligaments. Thus, increase of type VI collagen is the main contribution to the thickening of the ligamentum flavum. This may represent an adaptational and reparative process associated with disruption of elastic fibres. 相似文献
6.
N. Furuya K. Kawano H. Shimazu 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1976,25(5):447-463
Summary In decerebrate, unanesthetized cats, the brain stem was longitudinally cut at the midline from its dorsal to ventral surface with the cerebellum kept intact, eliminating neural interactions between the bilateral vestibular nuclei through the brain stem.Extracellular spike potentials of vestibular type I neurons identified by horizontal rotation were distinctly inhibited by contralateral vestibular nerve stimulation. This crossed inhibition was abolished by removal of the medial part of the cerebellum, indicating that the inhibition was mediated through the cerebellum. Neither aspiration of the flocculus on the recording side nor intravenous administration of picrotoxin eliminated transcerebellar crossed inhibition, suggesting that it is mediated through the cerebellar nuclei. When the fastigial, interposite and dentate nuclei were stimulated, inhibition of vestibular type I neurons was produced only from the contralateral fastigial nucleus. Cerebellocortical stimulation which inhibited fastigial type I neurons suppressed transcerebellar crossed inhibition. Effective sites for suppression of transcerebellar crossed inhibition were localized to lobules VI and VIIa in the vermal cortex on the side of labyrinthine stimulation.Intracellular recordings were made from type I neurons in the medial vestibular nucleus. Stimulation of the contralateral vestibular nerve and the contralateral fastigial nucleus produced IPSPs in these neurons with the shortest latency of 3.8 msec and 1.8 msec, respectively. The difference between these two latency values approximates the shortest latency of spike initiation of fastigial type I neurons in response to vestibular nerve stimulation. It is postulated that transcerebellar crossed inhibition is mediated through the fastigial nucleus on the side of labyrinthine stimulation. 相似文献
7.
Alain Verloes Yves Gillerot Jean-Paul Langhendries Jean-Pierre Fryns Lucien Koulischer 《American journal of medical genetics. Part A》1992,43(4):669-677
We report on a case of neonatal hypothalamic hamartoblastoma with holoprosencephaly, Hirschsprung disease, and tetramelic postaxial polydactyly. Twenty-seven previous cases of congenital hypothalamic embryonic tumours with associated congenital defects are reviewed. A classification in isolated, associated, and syndromal forms is proposed. The difficulties encountered in differential diagnosis between the syndromal form (mainly represented by the Pallister-Hall syndrome) and related diseases as Smith-Lemli-Opitz type II, holoprosencephaly-polydactyly, orofaciodigital type VI and hydrolethalus syndromes are outlined. Two pathogenic mechanisms are discussed: a classical pleiotropic model and single sequence model. The latter is sufficient to delineate syndromal hypothalamic hamartoblastoma. With the former, syndromal hypothalamic hamartoblastoma cannot be clearly recognized in the absence of a CNS tumour, a child with syndromal hypothalamic hamartoblastoma cannot be reliably diagnosed as Pallister-Hall rather than another MCA syndrome, and, ultimately, the existence of Pallister-Hall syndrome could be questioned, as it could only be the extreme expression of one or several other syndromes. As this hypothesis cannot be proven or disproven at this point, the authors suggest creating the concept of multiplex phenotype. “Cerebro-Acro-Visceral Early lethality multiplex syndrome” is suggested to encompass all the ambiguous cases. Within this complex, an operative classification key is proposed. © 1992 Wiley-Liss, Inc. 相似文献
8.
The properties of cells of the striate visual cortex (V1) have been studied in the normal adult sheep and in new-born lambs without visual experience, the majority of cells in the lamb are orientation specific, but 20% are non-oriented compared to only 3% cells in the adult. In the lamb there was little or no facilitation of binocularly-driven cells by simultaneous stimulation of both receptive fields. Cells which responded only to binocular stimulation of particular disparities ('obligate binocular' cells) were rarely encountered. In the adult, 15% of the sample were obligate binocular cells and a further 28% showed binocular facilitation. Simple and complex receptive fields were found in similar proportions in both new-born lambs and adult sheep. End-stopped cells comprised 17% of the sample in adults but only 2% in the lambs. Direction sensitive cells were found more frequently in the sheep (21% of cells) than in the lamb (4% of cells). It is concluded that facilitatory processes in binocular cells and inhibitory mechanisms generally, seem much less developed in the lamb. 相似文献
9.
Chang J Poole CA 《Osteoarthritis and cartilage / OARS, Osteoarthritis Research Society》1996,4(4):275-285
The chondron represents the chondrocyte and its pericellular microenvironment and plays an important role in the progression of osteoarthritis. Type VI collagen is preferentially localized in the pericellular microenvironment of adult articular cartilage and increases during osteoarthritis. In this study, we characterized the pericellular sequestration of type VI collagen in long-term chondrocyte-agarose cultures, and assessed the action of interleukin-1 on type VI collagen deposition and assembly. Immunohistochemical and biochemical analysis showed that cultured chondrocytes initiate type VI collagen sequestration immediately upon plating and continue pericellular matrix sequestration in a time dependent manner. Confocal microscopy confirmed the cell surface localization and pericellular accumulation of type VI collagen, while image analysis identified a 'cargo-net like' organization of type VI collagen around each chondrocyte. Quantitative analysis revealed a primary phase of rapid cell division and low levels of type VI collagen sequestration, followed by a secondary phase of relative growth stability and high levels of type VI collagen deposition. Interleukin-1 treated cultures showed increased sequestration and retention of type VI collagen in an expanded microenvironment surrounding the chondrocytes. The data suggests a role for type VI collagen in the differentiation of the pericellular microenvironment in vitro. The increased type VI collagen sequestration promoted by interleukin-1 was consistent with previous studies on osteoarthritic cartilage, and implies a functional role for type VI collagen in the chondron remodeling associated with cartilage degradation. 相似文献
10.
Arthrofibrosis is a disabling complication after trauma and surgery due to massive connective tissue proliferation. The etiology and pathogenesis have never been fully understood. A strong immune response may lead to activation and proliferation of fibroblasts with excessive and disordered deposition of matrix proteins. In similar pathological conditions, like lung fibrosis or superficial fibromatoses with fibrotic transformation an increased expression of collagen type VI has been reported. We investigated fibrotic tissue samples taken from 18 patients (average age: 32.7 years), who underwent arthrolysis of the knee joint because of symptomatic arthrofibrosis following ligament injury. The mean interval between trauma and arthrolysis was 13.8 months (range 4-50 months). Tissue samples were taken from the infrapatellar fat pad and intercondylar connective tissue. All samples were stained with HE. The expression of type III and VI collagen was studied immunohistochemically using an immunoperoxidase method for light microscopic visualization. Histologic analysis from patients with arthrofibrosis showed a synovial hyperplasia with cell infiltration and vascular proliferation compared to synovial tissue samples from knee joints without any detectable pathology. Subsynovial an increased deposition of matrix proteins was visible. Type VI collagen was widely distributed as a network subsynovial and around capillary walls. Type III collagen showed a diffuse distribution. Arthrofibrotic tissue is, similar to pathological conditions with fibrotic transformation characterized by an increased expression of collagen type VI. Collagen type VI may play an important role in matrix homeostasis. It serves as an anchoring element between collagen fibers and as a cell binding structure. 相似文献