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51.
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
52.
Revollo JR Körner A Mills KF Satoh A Wang T Garten A Dasgupta B Sasaki Y Wolberger C Townsend RR Milbrandt J Kiess W Imai S 《Cell metabolism》2007,6(5):363-375
Intracellular nicotinamide phosphoribosyltransferase (iNampt) is an essential enzyme in the NAD biosynthetic pathway. An extracellular form of this protein (eNampt) has been reported to act as a cytokine named PBEF or an insulin-mimetic hormone named visfatin, but its physiological relevance remains controversial. Here we show that eNampt does not exert insulin-mimetic effects in vitro or in vivo but rather exhibits robust NAD biosynthetic activity. Haplodeficiency and chemical inhibition of Nampt cause defects in NAD biosynthesis and glucose-stimulated insulin secretion in pancreatic islets in vivo and in vitro. These defects are corrected by administration of nicotinamide mononucleotide (NMN), a product of the Nampt reaction. A high concentration of NMN is present in mouse plasma, and plasma eNampt and NMN levels are reduced in Nampt heterozygous females. Our results demonstrate that Nampt-mediated systemic NAD biosynthesis is critical for beta cell function, suggesting a vital framework for the regulation of glucose homeostasis. 相似文献
53.
To investigate the functional expression of adenosine A3 receptor (A3AR) in mammalian living tissues, we generated an apoaequorin-transgenic mouse that expresses jellyfish apoaequorin
throughout its body. The expression of apoaequorin under the control of a strong CAG promoter was detected in various tissues,
including the abdominal skin, adipose, ear, brain, esophagus, heart, inferior vena cava vessel, kidney, lens, liver, lung,
pancreas, skeletal muscle, spleen, tail, testis, and thymus. The transgene was mapped to the C1–2 region of chromosome 16
by Fluorescence in situ hybridization analysis. Among these transgenic mouse tissues, we succeeded in detecting elevated responses
of intracellular Ca2+ as a light emission of aequorin induced by the A3AR agonist in the pancreas, brain, and testis, the last two of which are
known to be main tissues abundantly expressing A3AR. The A3AR agonist led to the phosphorylation of both extracellular signal-regulated
kinase 1/2 and protein kinase B in mouse pancreas, and all the intracellular responses via A3AR were antagonized by the A3AR-specific
antagonist. In addition, the mRNA expression of A3AR and the A3AR-induced intracellular responses were also found in the rat
pancreatic acinar cell line AR42J. These results suggest that pancreas is one of the main tissues functionally expressing
A3AR in mammalians in vivo, and that the present approach using transgenic mice that express apoaequorin throughout their bodies will facilitate the
functional analysis of proteins of interest.
Kazuya Yamano and Katsuhiro Mori contributed equally to this work 相似文献
54.
55.
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
56.
An epidermis-specific gene HrEpiC of the ascidian Halocynthia roretzi is activated in all presumptive blastomeres by the 64-cell stage. To explore the molecular mechanisms underlying the regulation of the timing of activation of HrEpiC, we studied the genomic organization and the 5' upstream sequences of HrEpiC associated with specific spatio-temporal expression of the gene. The restriction site mapping and sequencing of genomic clones showed that the H. roretzi genome contained two copies of HrEpiC gene, HrEpiC1 and HrEpiC2, aligned tandemly in about 8 kb of the genome. Analysis of various deletion constructs with the 5' flanking sequences of HrEpiC1 revealed that 103 bp of the 5' flanking region was sufficient for the minimal epidermis-specific expression of HrEpiC1 and that the region between -281 bp and -198 bp of the 5' flanking region was associated with the amplification of the minimal expression of the reporter gene in the epidermis. This module between -281 bp and -198 bp was also shown to be associated with the timing of the activation of HrEpiC1 by the 64-cell stage. We discussed how the spatio-temporal expression pattern of HrEpiC1 is regulated by the two modules. 相似文献
57.
M Shinada F Narumi Y Osada K Matsumoto T Yoshida K Higuchi T Kawasaki H Tanaka M Satoh 《Bioorganic & medicinal chemistry》2012,20(16):4901-4914
Phenserine is a potentially attractive drug for Alzheimer's disease. In order to further expand SAR study for inhibitions of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), the methyl group at the 3a-position of phenserine was replaced with an alkyl or alkenyl group, and its phenylcarbamoyl moiety was substituted at the o- or p-position. The synthetic methodology for these phenserine analogues includes the efficient cascade reactions for introduction of the 3a-substituent and assembly of the quaternary carbon center followed by reductive cyclization to the key pyrroloindoline structure. The bulkiness of the substituent at 3a-position of phenserine derivatives tends to reduce the inhibitory effect on AChE activity in the following order: methyl>ethyl>vinyl>propyl≈allyl>reverse-prenyl groups. Among the series synthesized, the 3a-ethyl derivative demonstrated the highest AChE selectivity. In construct, the 3a-reverse-prenyl derivative indicated modest BuChE selectivity. 相似文献
58.
Kashino Y Koike H Yoshio M Egashira H Ikeuchi M Pakrasi HB Satoh K 《Plant & cell physiology》2002,43(11):1366-1373
Using a recently introduced electrophoresis system [Kashino et al. (2001) Electrophoresis 22: 1004], components of low-molecular-mass polypeptides were analyzed in detail in photosystem II (PSII) complexes isolated from a thermophilic cyanobacterium, Thermosynechococcus vulcanus (formerly, Synechococcus vulcanus). PsbE, the large subunit polypeptide of cytochrome b(559), showed an apparent molecular mass much lower than the expected one. The unusually large mobility could be attributed to the large intrinsic net electronic charge. All other Coomassie-stained polypeptides were identified by N-terminal sequencing. In addition to the well-known cyanobacterial PSII polypeptides, such as PsbE, F, H, I, L, M, U, V and X, the presence of PsbY, PsbZ and Psb27 was also confirmed in the isolated PSII complexes. Furthermore, the whole amino acid sequence was determined for the polypeptide which was known as PsbN. The whole amino acid sequence revealed that this polypeptide was identical to PsbTc which has been found in higher plants and green algae. These results strongly suggest that PsbN is not a member of the PSII complex. It is also shown that cyanobacteria have cytochrome b(559) in the high potential form as in higher plants. 相似文献
59.