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101.
Participation of both host and virus factors in induction of severe acute respiratory syndrome (SARS) in F344 rats infected with SARS coronavirus
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Nagata N Iwata N Hasegawa H Fukushi S Yokoyama M Harashima A Sato Y Saijo M Morikawa S Sata T 《Journal of virology》2007,81(4):1848-1857
To understand the pathogenesis and develop an animal model of severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV), the Frankfurt 1 SARS-CoV isolate was passaged serially in young F344 rats. Young rats were susceptible to SARS-CoV but cleared the virus rapidly within 3 to 5 days of intranasal inoculation. After 10 serial passages, replication and virulence of SARS-CoV were increased in the respiratory tract of young rats without clinical signs. By contrast, adult rats infected with the passaged virus showed respiratory symptoms and severe pathological lesions in the lung. Levels of inflammatory cytokines in sera and lung tissues were significantly higher in adult F344 rats than in young rats. During in vivo passage of SARS-CoV, a single amino acid substitution was introduced within the binding domain of the viral spike protein recognizing angiotensin-converting enzyme 2 (ACE2), which is known as a SARS-CoV receptor. The rat-passaged virus more efficiently infected CHO cells expressing rat ACE2 than did the original isolate. These results strongly indicate that host and virus factors such as advanced age and virus adaptation are critical for the development of SARS in rats. 相似文献
102.
IL-28 elicits antitumor responses against murine fibrosarcoma 总被引:3,自引:0,他引:3
Numasaki M Tagawa M Iwata F Suzuki T Nakamura A Okada M Iwakura Y Aiba S Yamaya M 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(8):5086-5098
IL-28 is a recently described antiviral cytokine. In this study, we investigated the biological effects of IL-28 on tumor growth to evaluate its antitumor activity. IL-28 or retroviral transduction of the IL-28 gene into MCA205 cells did not affect in vitro growth, whereas in vivo growth of MCA205IL-28 was markedly suppressed along with survival advantages when compared with that of controls. When the metastatic ability of IL-28-secreting MCA205 cells was compared with that of controls, the expression of IL-28 resulted in a potent inhibition of metastases formation in the lungs. IL-28-mediated suppression of tumor growth was mostly abolished in irradiated mice, indicating that irradiation-sensitive cells, presumably immune cells, are primarily involved in the IL-28-induced suppression of tumor growth. In vivo cell depletion experiments displayed that polymorphonuclear neutrophils, NK cells, and CD8 T cells, but not CD4 T cells, play an equal role in the IL-28-mediated inhibition of in vivo tumor growth. Consistent with these findings, inoculation of MCA205IL-28 into mice evoked enhanced IFN-gamma production and cytotoxic T cell activity in spleen cells. Antitumor action of IL-28 is partially dependent on IFN-gamma and is independent of IL-12, IL-17, and IL-23. IL-28 increased the total number of splenic NK cells in SCID mice and enhanced IL-12-induced IFN-gamma production in vivo and expanded spleen cells in C57BL/6 mice. Moreover, IL-12 augmented IL-28-mediated antitumor activity in the presence or absence of IFN-gamma. These findings indicate that IL-28 has bioactivities that induce innate and adaptive immune responses against tumors. 相似文献
103.
Embryonic stem (ES) cells hold promise as a source for cell transplantation treatment of diseases such as type I diabetes. Further, cells releasing bioactive substances from ES cell progeny may be concentrated and purified for clinical applications. Although ES cell lines that express reporter genes have been established to isolate cells releasing bioactive substances, other difficulties must be overcome before these genetically modified cells can be used for gene therapy in human patients. Fluorescence- or magnetic-activated cell sorters are commonly used to isolate specific cells using antibodies against cell surface antigens. However, for some cells, such as insulin-producing beta cells, specific surface antigens have not yet been identified. In this study, we developed a simple and efficient method to identify and purify insulin- and alpha-fetoprotein-producing cells. A nitrocellulose membrane treated with anti-insulin or anti-alpha-fetoprotein antibodies was placed on a cell layer to trap insulin or alpha-fetoprotein released from the cells. The location of specific substance-producing cells was identified by immunostaining the membrane. The insulin-releasing cells were selectively collected from the culture dish using a cloning ring and transferred to another culture plate. 相似文献
104.
Heme proteins––hemoglobin and myoglobin possess esterase activities. Studies with purified hemoglobin from normal individuals
and diabetic patients revealed that the esterase activity as measured from hydrolysis of p-nitrophenyl acetate (p-NPA) was higher in diabetic condition and increased progressively with extent of the disease. HbA1c, the major glycated hemoglobin, which increases proportionately with blood glucose level in diabetes mellitus, exhibited
more esterase activity than the non-glycated hemoglobin fraction, HbA0, as demonstrated spectrophotometrically as well as by activity staining. Glycation influenced esterase activity of hemoglobin
by increasing the affinity for the substrate and the rate of the reaction. Both HbA0 and HbA1c-mediated catalysis of p-NPA hydrolysis was pH-dependent. Esterase activity of in vitro-glycated myoglobin (GMb) was also higher than that of its
non-glycated analog (Mb). The amplified esterase activities of hemoglobin and myoglobin might be associated with glycation-induced
structural modifications of the proteins. 相似文献
105.
Akita Y Otani H Matsuhisa S Kyoi S Enoki C Hattori R Imamura H Kamihata H Kimura Y Iwasaka T 《American journal of physiology. Heart and circulatory physiology》2007,292(5):H2051-H2059
We investigated the mechanism of exercise-induced late cardioprotection against ischemia-reperfusion (I/R) injury. C57BL/6 mice received treadmill exercise (60 min/day) for 7 days at a work rate of 60-70% maximal oxygen uptake. Exercise transiently increased oxidative stress and activated endothelial isoform of nitric oxide synthase (eNOS) during exercise and increased expression of inducible isoform of NOS (iNOS) in the heart after 7 days of exercise. The mice were subjected to regional ischemia by 30 min of occlusion of the left coronary artery, followed by 2 h of reperfusion. Infarct size was significantly smaller in the exercised mice. Ablation of cardiac sympathetic nerve by topical application of phenol abolished oxidative stress, activation of eNOS, upregulation of iNOS, and cardioprotection mediated by exercise. Treatment with the antioxidant N-(2-mercaptopropionyl)-glycine during exercise also inhibited activation of eNOS, upregulation of iNOS, and cardioprotection. In eNOS(-/-) mice, exercise-induced oxidative stress was conserved, but upregulation of iNOS and cardioprotection was lost. Exercise did not confer cardioprotection when the iNOS selective inhibitor 1400W was administered just before coronary artery occlusion or when iNOS(-/-) mice were employed. These results suggest that exercise stimulates cardiac sympathetic nerves that provoke redox-sensitive activation of eNOS, leading to upregulation of iNOS, which acts as a mediator of late cardioprotection against I/R injury. 相似文献
106.
An oncoprotein from the plant pathogen agrobacterium has histone chaperone-like activity 总被引:1,自引:0,他引:1
Terakura S Ueno Y Tagami H Kitakura S Machida C Wabiko H Aiba H Otten L Tsukagoshi H Nakamura K Machida Y 《The Plant cell》2007,19(9):2855-2865
Protein 6b, encoded by T-DNA from the pathogen Agrobacterium tumefaciens, stimulates the plant hormone-independent division of cells in culture in vitro and induces aberrant cell growth and the ectopic expression of various genes, including genes related to cell division and meristem-related class 1 KNOX homeobox genes, in 6b-expressing transgenic Arabidopsis thaliana and Nicotiana tabacum plants. Protein 6b is found in nuclei and binds to several plant nuclear proteins. Here, we report that 6b binds specifically to histone H3 in vitro but not to other core histones. Analysis by bimolecular fluorescence complementation revealed an interaction in vivo between 6b and histone H3. We recovered 6b from a chromatin fraction from 6b-expressing plant cells. A supercoiling assay and digestion with micrococcal nuclease indicated that 6b acts as a histone chaperone with the ability to mediate formation of nucleosomes in vitro. Mutant 6b, lacking the C-terminal region that is required for cell division-stimulating activity and interaction with histone H3, was deficient in histone chaperone activity. Our results suggest a relationship between alterations in nucleosome structure and the expression of growth-regulating genes on the one hand and the induction of aberrant cell proliferation on the other. 相似文献
107.
Iwata K Takabayashi A Miyachi E 《Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology》2007,14(1):P75-P76
In this study, we analysed the eye movements of flatfish for body tilting and compared with that of goldfish. The fish was fixed on the tilting table controlled by computer. The eye movements for body tilting along the different body axis were video-recorded. The vertical and torsional eye rotations were analysed frame by frame. In normal flatfish, vertical eye movement of left eye to leftward tilting was larger than that to rightward tilting. For head up or head down tilting, clear vertical eye movements were observed. On the other hand, torsional eye movements showed similar characteristics as goldfish. These results suggested that sacculus and lagena were important for otolith-ocular eye movements in flatfish. 相似文献
108.
109.
Ono T Kumakura I Arimoto M Hori K Dong J Iwata H Nokubi T Tsuga K Akagawa Y 《Gerodontology》2007,24(3):143-150
Objective: To investigate the influence of maximal bite force, maximal tongue pressure, number of mastications and swallowing on the oro‐pharyngeal residue in the elderly. Background: Oro‐pharyngeal residue in the elderly is an indication of dysphagia. Pharyngeal residue is especially critical as it may cause aspiration pneumonia, which is one of the major causes of death in elderly. Materials and methods: Videofluorographic recordings were performed on 14 elderly volunteers (six males, eight females, age range 65–93 years) without any history or symptoms of dysphagia. The subjects were instructed to consume 9 g of barium containing bread in two manners; free mastication and swallow (FMS: masticate and swallow freely), and limited mastication and swallow (LMS: swallow once after 30 chewing actions). The amount of oral and pharyngeal residue was evaluated using a 4‐point rating scale. Maximal occlusal force was measured by a pressure sensitive sheet, and maximal tongue pressure using a handy probe. Multiple regression analysis was performed to examine the influence of these items on the amount of oral and pharyngeal residue in FMS and LMS. Results: In FMS, age was found to be a factor which increased oral residue (p = 0.053), and the number of swallowing (p = 0.017) and the state of the prosthesis (p = 0.030) reduced the pharyngeal residue. In LMS, tongue pressure was a factor which reduced oral residue (p = 0.015) and increased pharyngeal residue (p = 0.008). Conclusion: It is suggested that in the elderly tongue pressure contributed to propulsion of the food bolus from oral cavity into the pharynx, and multiple swallowing contributed to the reduction in the amount of pharyngeal residue. 相似文献
110.
Tomoya Iwata 《Ecological Research》2007,22(4):619-628
In headwater streams, many aquatic insects rely on terrestrial detritus, while their emergence from streams often subsidizes
riparian generalist predators. However, spatial variations in such reciprocal trophic linkages remain poorly understood. The
present study, conducted in a northern Japanese stream and the surrounding forest, showed that pool–riffle structure brought
about heterogeneous distributions of detritus deposits and benthic aquatic insects. The resulting variations in aquatic insect
emergence influenced the distributions of riparian web-building spiders. Pools with slow current stored greater amounts of
detritus than riffles, allowing more benthic aquatic insects to develop in pools. The greater larval biomass in pools and
greater tendency for riffle insects to drift into pools at metamorphosis resulted in an emergence rate of aquatic insects
from pools that was some four to five times greater than from riffles. In the riparian forest, web-building spiders (Tetragnathidae
and Linyphiidae) were distributed in accordance with the emergence rates of aquatic insects, upon which both spider groups
heavily depended. Consequently, the riparian strips bordering pools had a density of tetragnathid spiders that was twice as
high as that of the riparian strips adjacent to riffles. Moreover, although limitations of vegetation structure prevented
the aggregation of linyphiid spiders around pools, linyphiid density normalized by shrub density was higher in habitats adjacent
to pools than those adjacent to riffles. The results indicated that stream geomorphology, which affects the storage of terrestrial
organic material and the export of such material to riparian forests via aquatic insect emergence, plays a role in determining
the strength of terrestrial–aquatic linkages in headwater ecosystems. 相似文献