全文获取类型
收费全文 | 615篇 |
免费 | 46篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 6篇 |
2019年 | 2篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 28篇 |
2012年 | 38篇 |
2011年 | 35篇 |
2010年 | 26篇 |
2009年 | 22篇 |
2008年 | 41篇 |
2007年 | 24篇 |
2006年 | 44篇 |
2005年 | 50篇 |
2004年 | 51篇 |
2003年 | 50篇 |
2002年 | 43篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 12篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有661条查询结果,搜索用时 437 毫秒
651.
Ikuko Ogata-Ikeda Hakaru SeoTakuya Kawanai Erika HashimotoYasuo Oyama 《Phytomedicine》2011,18(5):362-365
German chamomile (Matricaria recutita L.) is a popular ingredient in herbal teas. In previous study, micromolar bisabololoxide A, one of main constituents in German chamomile, exerted cytotoxic action on rat thymocyte, a normal non-proliferative cell. This result prompted us to study the effect of bisabololoxide A on proliferative cancer cells and to seek the possibility of its use with 5-fluorouracil, an anticancer agent. In this study, the effect of micromolar bisabololoxide A on human leukemia K562 cells was cytometrically examined. Although the incubation of K562 cells with 10 μM bisabololoxide A for 72 h did not significantly increase the percentage populations of dead cells and shrunken cells, the inhibitory action on the growth was obviously observed. It was not the case for the concentrations of less than 5 μM. The threshold concentration of bisabololoxide A to exert the cytotoxic action on K562 cells was ascertained to be 5-10 μM. Bisabololoxide A at 5-10 μM did not exert cytotoxic action on normal non-proliferative cells (rat thymocytes) in our previous study. Since the antiproliferative action of micromolar bisabololoxide A on cancerous cells was expected to be beneficial to cancer treatment, the modification of antiproliferative action of 5-fluorouracil (3-30 μM) by bisabololoxide A was studied. The combination of 5-fluorouracil and bisabololoxide further inhibited the growth of K562 cells although the additive inhibition of growth by bisabololoxide A became smaller as the concentration of 5-fluorouracil increased. Therefore, it is suggested that the simultaneous application of German chamomile containing bisabololoxide A may reduce the dose of 5-fluorouracil. 相似文献
652.
Dense vesicles mediate the final step in the delivery of seedproteins to vacuoles in developing pumpkin (Cucurbita sp.) cotyledons.To explore the vesicle-mediated transport system that is targetedto vacuoles in plant cells, we isolated the dense vesicles andexamined then for the presence of guanine nucleotide-bindingproteins. GTP-binding proteins of 25 kDa and 27 kDa were detectedon the isolated vesicles. The 25-kDa protein had dithiothreitol-dependentGTP-binding activity, but binding of GTP by the 27-kDa proteinshowed no such dependence. Binding of [ 相似文献
653.
Ikuko Fujisaki Leonard G. Pearlstine Frank J. Mazzotti 《Wetlands Ecology and Management》2010,18(1):17-26
As part of the Everglades Depth Estimation Network (EDEN) project, this paper describes validation of raster-based daily surface
water depth models of the Greater Everglades in Florida developed using real-time stage data and elevation data obtained from
a survey with an aerial height finder. Daily median stage data obtained at over 200 locations were interpolated using the
multiquadric radial basis function. Surface water depth was obtained by subtracting a digital elevation model from the interpolated
stage raster. The model was validated with 751 independent field measurements of surface water depth between 1999 and 2004.
Correlations between prediction error and both density of the monitoring gages and distance from a major linear geographic
feature, such as a canal, were weak, suggesting that the error does not depend on these features. South Florida has distinct
dry and wet seasons and the study area is dominated by sawgrass and wet prairie. Seasonality and ground vegetation type significantly
affect prediction error. Correlation between observed and predicted water depth was high for all combination of season and
vegetation type (0.83–0.96). Model validation using an equivalence test provided evidence of equivalence between predicted
and observed water depths in dry season prairie-dominated and wet season sawgrass-dominated areas with the strict test and
in dry season sawgrass-dominated areas with the liberal test, but not in wet season prairie-dominated areas. Equivalence between
observed and predicted water depth for both dry season sawgrass- and wet season prairie-dominated areas were confirmed with
the strict test after further model calibrations using linear regressions. 相似文献
654.
Ikuko Kitaba Mao Harada Masayuki Hyodo Shigehiro Katoh Hiroshi Sato Mariko Matsushita 《Palaeogeography, Palaeoclimatology, Palaeoecology》2011,299(1-2):227-239
We report climate and sea-level variation for the marine oxygen isotope stage (MIS) 21, encompassing the end of the Mid-Pleistocene climate transition (MPT), based on pollen, diatom, and sulfur records from a 50-m thick sequence in a core from Osaka Bay. An extremely warm climate coincided with the sea level highstand of substage 21.5, when the warm-temperate element Quercus (Cyclobalanopsis) exceeds 40% of total arboreal pollen. This was followed by a warm-temperate to temperate and humid climate that continued until the end of MIS 21. A linear age model shows that climate was dominated by precessional cyclicity, with an inverse correlation between temperature and precipitation. The postglacial sea-level rise reached its highest peak in substage 21.5, when paleo-Osaka Bay reached its maximum extent including Kyoto and Nara Basins. At this time pelagic diatoms were dominant in the central part of the bay. Sea level dropped below the Osaka Bay sill (about ? 60 m at present) during substage 21.4, followed by a rise above the sill in substage 21.3, and a drop at 21.2. Sea level remained below the sill during substage 21.1. The thermal maximum and sea level peak occurred just after the rapid postglacial sea level rise, after which there was a gradual decline in temperature and sea level accompanied by precession-related oscillations; these features are typical of the post-MPT interglacials dominated by 100-ka cyclicity. These features may be a sign of termination of the MPT. 相似文献
655.
Sixty-seven isolates of the southern blight fungus from Japan were divided into five groups based on ITS-RFLP analysis of
nuclear rDNA. Morphological characters of sclerotia varied between groups. Three groups were reidentified asSclerotium rolfsii, and two resembledS. delphinii in RFLP patterns and/or in having large sclerotia and relatively low optimal growth temperature (28°C). Sclerotia of the
latter, however, varied in size according to temperature and became indistinguishable from those ofS. rolfsii at high temperatures. Hyphal anastomosis (imperfect fusion) was observed between different ITS-RFLP groups, as well as between
different isolates belonging to the same groups. These results indicate that populations of this fungus in Japan consists
of several different subgroups, although morphological differences are not always evident. 相似文献
656.
Induction of avascular yolk sac due to reduction of basic fibroblast growth factor by retinoic acid in mice 总被引:3,自引:0,他引:3
657.
We studied the ionic balance during diurnal changes in the levelsof accumulated malic acid and hydrogen ion in the vacuoles ofGraptopetalum paraguayense, a crassulacean acid metabolism (CAM)plant. There was a clear diurnal rhythm of the pH and the totalmalic acid content, but the amount of negative charges due tothe unprotonated carboxyl groups of malic acid remained approximatelyconstant. The negative charges were balanced by the positivecharges of cations, which were also constant throughout thediurnal CAM rhythm. The results gave evidence for the electroneutralityof the translocation of the malic acid and protons across thetonoplast membrane. (Received July 30, 1987; Accepted March 17, 1988) 相似文献
658.
Akira Sano Noriko Yamauchi Yasuo Kakimoto Osamu Komure Jun Kawai Fumitada Hazama Kazuyo Kuzume Nozomi Sano Ikuko Kondo 《Human genetics》1994,93(6):699-702
Anticipation refers to the progressively earlier onset and increase in disease severity in successive generations. We studied four families with hereditary dentatorubral-pallidoluysian atrophy (DRPLA), a neurodegenerative disease, and anticipation was present in the mode of inheritance. In subsequent generations DRPLA shows an earlier onset and more severe as well as additional symptoms. Older onset patients suffer from cerebellar ataxia with or without dementia, whereas younger onset patients present as progressive myoclonus epilepsy syndrome, which consists of mental retardation, dementia, and cerebellar ataxia as well as epilepsy and myoclonus. Anticipation with paternal transmission was significantly greater than with maternal transmission. 相似文献
659.
Autoantibodies recognizing proteins copurified with PCNA in patients with connective tissue diseases
Ken Takeuchi Kazuhiko Kaneda Ikuko Kawakami Yoshinari Takasaki Hiroshi Hashimoto 《Molecular biology reports》1996,23(3-4):243-246
Objective. Proliferating cell nuclear antigen (PCNA), one of the target antigen recognized by lupus sera, has been reported to be present as a subnuclear multi-peptide complex. But autoantibodies reacting with components of PCNA complex are poorly understood. To study the specificity of those autoantibodies, immunoreactivities of autoimmune sera against purified PCNA antigen were studied. Methods. PCNA antigens were purified from rabbit thymus extract by affinity column using murine monoclonal antibodies (mAbs) to PCNA, TOB7, TO17 and TO30. Immunoreactivities of autoimmune sera against purified PCNA were analyzed by WB. Results. PCNA antigen purified by serum AK predominantly showed a 34 kD band specific for PCNA in SDS-PAGE. When antigens were purified by anti-PCNA mAb TOB7 and TO30 which are known to be targeting different epitopes on PCNA antigen, SDS-PAGE analysis showed various mol. wt of proteins in addition to the 34 kD PCNA while both AK and mAbs reacted only with 34 kD PCNA in WB. In WB using PCNA purified by TOB7, various immunoreactivities were observed at 150, 66, 58, 48, 45, 37, 32 and 16 kDa in sera from patients with connective tissue diseases. Conclusions. These results suggested that many of the proteins copurified with PCNA were also targets of autoimmune responses and these autoantibody experssion may be induced through antigen-driven mechanisms.Abbreviations mAb
monoclonal antibody
- PCNA
proliferating cell nuclear antigen
- PCNA/AK
PCNA affinity purified by antibodies from patient serum AK
- PCNA/TO30
PCNA purfied by mAb TO30
- PCNA/TOB7
PCNA purified by mAb TOB7
- SLE
systemic lupus erythematosus 相似文献
660.
Yumi Sugimoto Jun Yamada Ikuko Kimura Yoshiko Watanabe Kazuyoshi Horisaka 《Neurochemical research》1994,19(1):19-22
Effects of tryptamine on tolbutamide-induced hypoglycemia were investigated in mice. Tryptamine significantly inhibited hypoglycemia elicited by tolbutamide. The inhibitory effects of tryptamine were strongly blocked by the 5-HT1 and 5-HT2 receptor antagonist methysergide and the 5-HT2 receptor antagonist ketanserin, while the 5-HT3 receptor antagonist ICS 205–930 was without effect. Tryptamine induced hyperglucagonemia in tolbutamide-treated mice, and this effect elicited by tryptamine was strongly inhibited by the 5-HT2 receptor antagonist ketanserin. These results suggest that the inhibitory effects of tryptamine on tolbutamide-induced hypoglycemia are mediated by 5-HT2 receptors and that tryptamine is involved in glucagon release. 相似文献