全文获取类型
收费全文 | 503篇 |
免费 | 21篇 |
专业分类
524篇 |
出版年
2023年 | 2篇 |
2021年 | 2篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 3篇 |
2016年 | 10篇 |
2015年 | 10篇 |
2014年 | 15篇 |
2013年 | 26篇 |
2012年 | 31篇 |
2011年 | 35篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 28篇 |
2007年 | 14篇 |
2006年 | 18篇 |
2005年 | 16篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 22篇 |
2001年 | 13篇 |
2000年 | 18篇 |
1999年 | 29篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 5篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 5篇 |
排序方式: 共有524条查询结果,搜索用时 0 毫秒
101.
102.
103.
104.
S Yodozawa Y Tsunoda T Funai Y Tashiro 《The journal of histochemistry and cytochemistry》1991,39(10):1311-1319
We investigated spatiotemporal changes in cytoplasmic free Ca2+ concentration ([Ca2+]i) in norepinephrine (NE)-stimulated and fura-2-loaded individual H-35 rat hepatoma cells, using digital imaging microscopy and high time-resolution microspectrofluorometry. Application of NE (5 x 10(-6) M) resulted in an initial transient increase in [Ca2+]i, followed by a small sustained [Ca2+]i plateau above the pre-stimulation level. The initial peak and the small sustained plateau originated from intracellular stores and the extracellular space, respectively. The initial transient evoked by NE was totally blocked by phentolamine, an alpha-adrenergic antagonist, but was not blocked by either pre-incubation with nominally Ca(2+)-free medium or by pre-treatment of cells with La3+. On the other hand, the sustained plateau was eliminated by Ca(2+)-free medium or La3+. Therefore, H-35 cells have a Ca(2+)-signaling pathway which is activated via alpha-adrenergic receptors. Mn2+ entered the cytosol after NE stimulation, as shown by quenching of fura-2. This indicates that H-35 hepatoma cells possess Mn(2+)-permeable Ca2+ channels at the plasma membrane. In addition, the Ca2+ efflux pattern from H-35 cells to the extracellular space during NE stimulation was visualized by digital imaging microscopy when free fura-2 was equilibrated between the cells and the extracellular space. The efflux of Ca2+ from H-35 begins between the initial [Ca2+]i transient and the sustained [Ca2+]i plateau. 相似文献
105.
H Tsunoda S Katayama Y Sakuma S Tanaka K Tsukidate S Abe I Yamatsu K Katayama 《Prostaglandins, leukotrienes, and essential fatty acids》1991,42(1):51-56
6-Hydroxy-2-(4-sulfamoylbenzylamino)-4,5,7-trimethylbenzothiazo le hydrochloride (E6080), an orally active and selective 5-lipoxygenase inhibitor, dose-dependently inhibited the bronchospasm induced by antigen (ovalbumin) inhalation in sensitized conscious guinea pigs. The inhibitory effect of E6080 was more potent than that of a typical 5-lipoxygenase inhibitor, AA861, but less than that of a leukotriene (LT) antagonist, LY171883. When airway infiltration of neutrophils and eosinophils was measured in bronchoalveolar lavage fluid (BALF) at 6 h after antigen inhalation by passively sensitized guinea pigs, the inhibitory effect of E6080 on neutrophil infiltration was more marked than that on eosinophil infiltration. The inhibitory effect of E6080 on bronchoalveolar cellular infiltration and bronchoepithelial damage was confirmed by examination of photomicrographs of the lung. In addition to the above pharmacological effects, E6080 inhibited the increase in BALF levels of both i-LTC4 and i-LTB4. These results suggest that E6080 may prove to be effective for the treatment of asthma, in which large amounts of leukotrienes (LTs) are elaborated. 相似文献
106.
The present study was undertaken to determine the efficiency of HVJ treatment and electrofusion for pronuclear transplantation in the mouse. The output voltage and duration of the pulses were fixed to 200 μsec at 10 V or to 150 μsec at 15 V for electrofusion, because the maximum rates of blastomere fusion of 2-cell embryos and development of fused embryos in vitro were obtained under these conditions. Although the proportion of eggs with fused karyoplast (78%) and the fused eggs developed to morulae or blastocysts (67%) was significantly lower than those obtained after HVJ treatment (94% and 94%), the proportion of pregnant recipients and young obtained after treatment of fused eggs was not significantly different between these two procedures. It is advised that electrofusion can be used as a fusogenic procedure for pronuclear transplantation in the mouse in some cases where HVJ cannot be applied. 相似文献
107.
Y Tsunoda H Takeda T Otaki M Asaka I Nakagaki S Sasaki 《Biochimie et biologie cellulaire》1988,66(4):279-287
In gastrin-stimulated, aequorin-loaded parietal cells from guinea pig gastric mucosa, a rapid but transient increase in the cytosolic free Ca2+ concentration ([Ca2+]i), owing to Ca2+ released from the store(s), and a more prolonged Ca2+ entry from outside the cells were observed. However, there was a little increase in [Ca2+]i when similar measurements were assessed by quin 2 or fura-2 in physiological saline. However, depletion or elimination of Na+ from the incubation medium caused a significant increase in the [Ca2+]; response to gastrin as measured by quin 2. These findings suggest that aequorin and quin 2 (or fura-2) provide information about different aspects of Ca2+ homeostasis and that there is an inhomogeneity of [Ca2+]i in the cytoplasm during gastrin stimulation. By the gastrin stimulation, the intracellular Ca2+ gradients were shifted from the unidentified portion(s) to the restricted apical cytoplasm, as determined by electron probe X-ray microanalysis. Therefore, localization and identification of the source of intracellular Ca2+ as a pool were determined by an X-ray microanalyzer. In the resting state, the tubulovesicle had high Ca2+ concentration compared with the level in the apical cytoplasm. Cells treated with the Ca2+ ionophore ionomycin had a decreased tubulovesicular Ca2+ level, followed by a reciprocal increase in area of the canalicular membrane. The secretory canaliculus in stimulated cells had lower Ca2+ or higher K+ and Cl- concentrations than that of tubulovesicles or cytoplasm in the resting state, respectively. These findings suggest that the Ca2+ pool of the parietal cell is in the tubulovesicles and (or) luminal cell membrane and that the Ca2+ released from the store(s) may mediate a flow of K+ or Cl- into the secretory canaliculus. 相似文献
108.
Electron probe X-ray microanalysis revealed that cytoplasmic Ca2+ concentration increased in the restricted apical cytoplasm during stimulation of isolated guinea pig parietal cells with gastrin. Furthermore, this study, using 45Ca2+, aequorin and fura-2, revealed the mechanism involved in intracellular Ca2+ shifts caused by gastrin and the involvements of inositol 1,4,5-trisphosphate (IP3) and diacylglycerol in producing those shifts. The gastrin-mediated and IP3-sensitive Ca2+ pool was located in the smooth-surfaced membrane-enriched areas and released Ca2+ in the initial phase. Gastrin-mediated Ca2+ mobilization was also evoked by diacylglycerol, comprising an intracellular Ca2+ mobilization followed by a late, sustained and more localised Ca2+ entry from the extracellular space. 相似文献
109.
E L Stuenkel Y Tsunoda J A Williams 《Biochemical and biophysical research communications》1989,158(3):863-869
Microspectrofluorometry of fura-2 was utilized to monitor [Ca2+]i in single acinar cells stimulated with a cholinergic agonist and cholecystokinin. A similar amplitude of agonist induced Ca mobilization between single cell and populational approaches was observed. New findings in single cells not observable in populations of cells include: 1) the maintenance of a sustained elevation in [Ca2+]i above basal levels throughout agonist application, 2) the reloading of the agonist-sensitive Ca pool only following removal of the agonist and 3) the presence of oscillations of [Ca2+]i in response to agonist application which is enhanced at lower agonist concentrations. 相似文献
110.
Ponds are common features of the landscape and are considered important for freshwater biodiversity conservation. Although
fish have a significant impact on the lentic ecosystems, the environmental factors that regulate fish assemblages in human-created
water bodies, such as irrigation ponds, remain unclear. We evaluated the relationship between environmental factors and the
fish assemblage structure in 31 ponds located in northern Japan. Species richness (range: 1–9) was positively correlated with
the size of the inflow channel. Multivariate analyses revealed that the size of the inflow channel was a better predictor
for species richness than lake morphology (surface area and maximum depth), vegetation coverage, water quality (turbidity,
pH, DO, and EC), distance to the main channel, and distance to an adjacent pond. Species richness was significantly different
between ponds with and without an inflow channel. Furthermore, three of the four most commonly observed species are thought
to be relatively tolerant to low oxygen. Given that ponds have a relatively high local extinction rate resulting from exposure
to stressful conditions, such as low oxygen and/or small population sizes, our results suggest that immigration from surrounding
water bodies plays an important role in maintaining species richness of pond-dwelling fish. 相似文献