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231.
232.
Interactions between cells and between tissues are importantin the development and morphogenesis of higher plants. Attemptsto characterize the role of the cell wall in such interactionshave benefited from the use of carrot (Daucus carota L.) culturedcells in vitro as a model system. The development of carrotcells in culture can be divided into three processes: the acquisitionof embryogenic competence; the development of the embryo; andthe maturation and dormancy of the embryo. Induction of non-embryogeniccallus is accompanied by weakened intercellular attachment,decreased levels of endogenous ABA and a decrease in responsivenessto exogenous ABA. Cell wall polysaccharides are known to beinvolved in various developmental and morphogenetic events.In carrot cultured cells, possible roles in intercellular attachmenthave been proposed for arabinan and xylose in the neutral sugarregions of pectins, and various extracellular proteins havebeen shown to be involved in somatic embryogenesis in vitro.Some of these proteins are also present around and/or in zygoticembryos, possibly being involved in the formation and functionsof zygotic embryos and seeds. A 57-kDa extracellular solubleglycoprotein that binds to insulin-like peptides and an 18-kDaextracellular insoluble cystatin that inhibits the proteinasesof germinating seeds of carrot might be involved in cellularsignal transduction and inter-tissue interaction, respectively,in carrot seeds.
1 Recipient of the JSPP Young Investigator Award, 1997 相似文献
233.
Shiota Hajime; Satoh Rika; Watabe Ken-ichi; Harada Hiroshi; Kamada Hiroshi 《Plant & cell physiology》1998,39(11):1184-1193
A carrot gene homologous to the ABI3 gene of Arabidopsis wasisolated from a carrot somatic embryo cDNA library and designatedC-ABI3. The sequence of C-ABI3 was very similar to those ofABI3 of Arabidopsis and VP1 of maize in certain conserved regions.The expression of C-ABI3 was detected specifically in embryogeniccells, somatic embryos and developing seeds. Thus, expressionof C-ABI3 was limited to tissues that acquired desiccation tolerancein response to endogenous or exogenous abscisic acid (ABA).Endogenous levels of ABA in seeds increased transiently andthen desiccation of seeds started. The expression of C-ABI3in developing seeds was observed prior to the increase in levelsof endogenous ABA that was followed by desiccation of seeds.In transgenic mature leaves in which C-ABI3 was ectopicallyexpressed, expression of ECP31, ECP63 and ECP40 was inducedby treatment with ABA, which indicates that the expression ofECP genes was controlled by the pathway(s) that involved C-ABI3and ABA. This suggests that C-ABI3 has the same function asVP1/ABI3 factor in carrot somatic embryos. (Received March 4, 1998; Accepted September 4, 1998) 相似文献
234.
Measurement of intracellular Ca2+ concentration ([Ca2+]i) has been a fundamental technique in cell biology. However, most investigations have used cultured or isolated cells as an experimental model, and consequently can provide only limited insight into the mechanisms that operate in tissue in situ. Useful information may be obtained by studying intact tissue specimens. High-speed confocal microscopes that can acquire digital images at video rate have recently been developed. These confocal microscopes which can acquire data in real-time enable [Ca2+]i dynamics of individual cells in intact tissue specimens to be observed. The present paper examines the use of fluorescent microscopy and confocal microscopy for [Ca2+]i imaging of living tissue. We analyzed the dynamics of the duodenal gland, lacrimal gland, intestinal smooth muscles, arterioles, myenteric plexus, and dorsal root ganglion. In these specimens, individual cells exhibited different [Ca2+]i dynamics, and the responses to transmitters/modulators were heterogeneous. In conclusion, real-time imaging provides a useful tool for observing dynamic changes in cells in situ, and it may lead to improve understanding tissue physiology. 相似文献
235.
236.
Yumiko Nakagaito Motonobu Satoh Haruhiko Kuno Toshi Iwama Masao Takeuchi Akira Hakura Touho Yoshida 《In vitro cellular & developmental biology. Animal》1998,34(7):585-592
Summary We have established a multipotent clonal cell line, named MEB5, from embryonic mouse forebrains after the infection of a retrovirus
carrying E7 oncogene of human papillomavirus type 16. MEB5 cells proliferated in serum-free, epidermal growth factor (EGF)-supplemented
medium. They expressed markers for neural precursor cells (nestin, A2B5, and RC1) and did not express markers for neurons
(class III β-tubulin), astrocytes (glial fibrillary acidic protein), and oligodendrocytes (galactocerebroside). MEB5 cells
were stably maintained in an undifferentiated state with a diploid karyotype in the presence of EGF. When they were deprived
of EGF, about 50% of the cells died due apoptosis within 24 h. The remaining cells differentiated into neurons, astrocytes,
or oligodendrocytes within 2 wk. The newly developed cells with neuronal morphology were immunoreactive for γ-aminobutyric
acid and exhibited neuronal electrophysiological properties. When MEB5 cells were treated with leukemia inhibitory for 7 d,
they were induced to differentiate exclusively into astrocytes. These results inducate that MEB5 is a cell line with characteristics
of EGF-dependent, multipotent neural precursor cells. This cell line should provide a good model system to study the mechanisms
of survival, proliferation, and differentiation of the multipotent precursor cells in the central nervous system. 相似文献
237.
Bialek-Bylka Grazyna E. Fujii Ritsuko Chen Chun-Hai Oh-oka Hirozo Kamiesu Akihisa Satoh Kazuhiko Koike Hiroyuki Koyama Yasushi 《Photosynthesis research》1998,58(2):135-142
Carotenoids were extracted, at 4 °C in complete darkness and under nitrogen atmosphere, from the reaction center (RC) of a green-sulfur bacterium and the Photosystem (PS) I RC of a cyanobacterium; each extract was subjected to high-performance liquid chromatography (HPLC) using an apparatus equipped with a two-dimensional diode-array detector in order to spectroscopically identify cis–trans carotenoids while performing HPLC analysis. In the extract from the RC of Chlorobium tepidum, 15-cis and all-trans--carotenes as well as 13-cis-, 15-cis- and all- trans-chlorobactenes (in the order of elution) were identified, whereas in the extract from the PS I RC of Synechococcus vulcanus, 15-cis-, all-trans- and 9-cis--carotenes were found. Thus, the universal presence of 15- cis carotenoids in the 'iron sulfur-type' RCs has been shown in addition to the previous cases of the 'quinone-type' RCs. 相似文献
238.
Wadano Akira Nishikawa Keisuke Hirahashi Tomohiro Satoh Ryohei Iwaki Toshio 《Photosynthesis research》1998,56(1):27-33
The dependence of the activity of phosphoribulokinase isolated from a cyanobacterium, Synechococcus PCC7942, on Mg2+ showed that its real substrates were Mg-ATP and free D-ribulose 5-phosphate. On the basis of results of kinetic inhibition studies and previously reported result of affinity chromatography, an ordered bi bi mechanism in which Mg-ATP binds before ribulose 5-phosphate is proposed. The Km values for ATP and D-ribulose 5-phosphate were 0.09 and 0.27 mM, respectively. Ki values of ADP and D-ribulose 1,5-bisphosphate were 0.32 and 10.0 mM, respectively. Inhibition constants Ki1 and Ki2 for 6-phosphogluconate were 9.3 and 0.49 mM. Kia was 0.13 mM. New kinetics on PRK gave higher control coefficient than the kinetics on Spinach PRK did in the model with PRK activity from 175 to 1000 µmol min–1 mg–1 chl. 相似文献
239.
Enami Isao; Mochizuki Yasuki; Takahashi Seitaro; Kakuno Tomisaburo; Horio Takekazu; Satoh Kazuhiko; Katoh Sakae 《Plant & cell physiology》1990,31(5):725-729
Treatment of oxygen-evolving Photosystem II complexes, whichlack light-harvesting chlorophyll a/b proteins, with a seriesof disuccinimidyl esters with different chain lengths yieldeda crosslinked product which consisted of one molecule each ofthe extrinsic 33 kDa and 23 kDa proteins. In addition, crosslinkingbetween the 33 kDa protein and the chlorophyll-carrying 47 kDaprotein and between the 23 kDa and 17 kDa proteins was confirmed.Thus, the three extrinsic proteins are closely associated witheach other to form a complex which is attached to the PS IIreaction center complexes. (Received December 1, 1989; Accepted May 2, 1990) 相似文献
240.
Takako Yasuda Shoji Oda Yusuke Hibi Satomi Satoh Kento Nagata Kei Hirakawa Natsumaro Kutsuna Hiroshi Sagara Hiroshi Mitani 《PloS one》2015,10(6)
Radiation therapy (RT) is pivotal in the treatment of many central nervous system (CNS) pathologies; however, exposure to RT in children is associated with a higher risk of secondary CNS tumors. Although recent research interest has focused on the reparative and therapeutic role of microglia, their recruitment following RT has not been elucidated, especially in the developing CNS. Here, we investigated the spatiotemporal dynamics of microglia during tissue repair in the irradiated embryonic medaka brain by whole-mount in situ hybridization using a probe for Apolipoprotein E (ApoE), a marker for activated microglia in teleosts. Three-dimensional imaging of the distribution of ApoE-expressing microglia in the irradiated embryonic brain clearly showed that ApoE-expressing microglia were abundant only in the late phase of phagocytosis during tissue repair induced by irradiation, while few microglia expressed ApoE in the initial phase of phagocytosis. This strongly suggests that ApoE has a significant function in the late phase of phagocytosis by microglia in the medaka brain. In addition, the distribution of microglia in p53-deficient embryos at the late phase of phagocytosis was almost the same as in wild-type embryos, despite the low numbers of irradiation-induced apoptotic neurons, suggesting that constant numbers of activated microglia were recruited at the late phase of phagocytosis irrespective of the extent of neuronal injury. This medaka model of microglia demonstrated specific recruitment after irradiation in the developing CNS and could provide a useful potential therapeutic strategy to counteract the detrimental effects of RT. 相似文献