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721.
Akira Hattori Shoji Iwasaki Katsuhito Murase Masafumi Tsujimoto Masahiro Sato Kyozo Hayashi Michiaki Kohno 《FEBS letters》1994,340(3):177-180
A possible interaction between tumor necrosis factor- (TNF) and other cytokines/growth factors in stimulating the production of nerve growth factor (NGF) in Swiss 3T3 cells was studied. TNF's stimulatory activity on fibroblast NGF production was synergized by interleukin-1 (IL-1), IL-1β and interferon-γ (IFN-γ), but was antagonized by transforming growth factor-β (TGF-β). The most remarkable synergistic effect was observed between TNF and IL-1/β; as little as 0.003 ng/ml of IL-1β markedly enhanced TNF's stimulatory activity on NGF production in the cells. These findings reinforce the idea that TNF, in concert with IL-1/β, plays an essential role in regulating the regeneration of peripheral nerves following injury through an indirect mechanism by which it stimulates NGF production in fibroblasts. 相似文献
722.
723.
Sadami Ohtsubo Mitsuyoshi Kanno Hiroyoshi Miyahara Shuhei Kohno Yosuke Koga Isao Miura 《FEMS microbiology ecology》1993,12(1):39-50
Abstract A highly sensitive method for the quantification of methanogens in anaerobic digestor sludges was developed, based on an analysis of ether-linked glycerolipids. Core lipids were prepared from total lipids by HF treatment and mild methanolysis, and these core lipids were quantified as the corresponding 9-anthroyl derivatives by high-performance liquid chromatography with fluorescence detection. The amounts, in terms of cell carbon content, of Methanosaeta and Methanosarcina were proportional to the amounts of α-hydroxyarchaeol and β-hydroxyarchaeol, respectively. Moreover, the total amount of core lipids was well correlated with the cell mass of aceticlastic and H2 /CO2 -consuming methanogens. The limit of detection for Methanosaeta concilii was 17 ng of cell carbon when the signal/noise ratio was 3. This method allowed us to quantitate aceticlastic methanogens with high accuracy and to make a rough estimate of total methanogenic cells without any interference by the multifarious impurities that are present in anaerobic sludges. These results suggest that the present method will be a useful tool for investigations of methanogenic ecosystems. 相似文献
724.
The various species of Japanese hagfish, namely, Eptatretus okinoseanus (types A and B), Eptatretus burgeri and Myxine garmani, are known to eliminate a fraction of their chromosomes during early embryogenesis. High molecular weight DNA from germ line cells and somatic cells of these hagfish species was isolated and digested with different restriction enzymes. The DNA fragments were separated by agarose gel electrophoresis. Digestion with BamHI and DraI generated two weak bands and one weak band, respectively, that were estimated to be about 90, and 180 bp and about 90 bp long and were limited to the germ line DNA in both types of E. okinoseanus. DNA filter hybridization experiments showed that the two BamHI fragments and the one DraI fragment were present almost exclusively in the germ line DNA of E. okinoseanus. Thus, these DNA fragments appear to be eliminated during embryogenesis. Moreover, evidence was obtained that these fragments are highly and tandemly repeated. Molecular cloning and sequence analysis revealed that the BamHI fragments are mainly composed of a family of closely related sequences that are 95 bp long (EEEo1, for Eliminated Element of E. okinoseanus 1), and the DraI fragment is composed of another family of closely related sequences that are 85 bp long (EEEo2). The two DNA families account for about 19% of the total eliminated DNA in E. okinoseanus type A. Fluorescence in situ hybridization experiments demonstrated that the two families of DNA are located on several C-band-positive, small chromosomes that are limited to germ cells in both types of E. okinoseanus.by W. Hennig 相似文献
725.
Yumi Kohno Hideo Akiyoshi Maki Fukunaga Kazuo Shiraki 《Virchows Archiv. B, Cell pathology including molecular pathology》1993,63(1):317-324
The ultrastructure of the cellular contacts and bile canaliculi was examined in cultured neonatal (day 5) rat hepatocytes
to elucidate the development of cellular polarity. A new scanning electron microscopic technique for cultured hepatocytes
allowed a view of cell-cell attachment and the entire cell surface, including the underside on plastic dishes. At 3 h after
plating, neonatal hepatocytes were shown to be round, with loss of the preferential localization of cell organelles. After
6 h of culture, the cells had become oblong; they were aggregated in groups of several cells and the cellular contacts were
not as rigid or as straight as those in adult hepatocytes. Transmission electron microscopy showed the biliary functional
polarity to be like that in vivo. On the undersurfaces of adjacent neonatal heptocytes a hemicanalicular structure lined with
microvilli was found, which probably corresponds to the ultrastructure of bile canaliculi in vivo. However, no canaliculi
or orifices of bile channels were found in adult hepatocytes. These results suggest that in neonatal rat hepatocyts the formation
of tight rigid cellular contacts was suppressed. Modulation of cell membranes appeared on the undersurfaces of neonatal hepatocytes
in early culture stages. The difference in the development of cellular polality could be caused by the proliferating activity
of neonatal hepatocytes. 相似文献
726.
Scavenging Effects of Dopamine Agonists on Nitric Oxide Radicals 总被引:4,自引:0,他引:4
Sakiko Nishibayashi Masato Asanuma †Masahiro Kohno Marvin Gómez-Vargas Norio Ogawa 《Journal of neurochemistry》1996,67(5):2208-2211
Abstract: It has recently been considered that free radicals are closely involved in the pathogenesis of Parkinson's disease (PD), and the level of nitric oxide radical (• NO), one of the free radicals, is reported to increase in PD brain. In the present study, we established a direct detection system for • NO in an in vitro • NO-generating system using 3-(2-hydroxy-1-methylethyl-2-nitrosohydrazino)- N -methyl-1-propanamine as an • NO donor and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO) by electron spin resonance (ESR) spectrometry and examined the quenching effects of the dopamine agonists pergolide and bromocriptine on the amount of • NO generated. • NO appeared to be scavenged by pergolide and, to a lesser extent, by bromocriptine. In the competition assay, the 50% inhibitory concentration values for pergolide and bromocriptine were estimated to be ∼23 and 200 µ M , respectively. It was previously reported that in vivo treatment of pergolide and bromocriptine completely protected against the decrease in levels of striatal dopamine and its metabolites in the 6-hydroxydopamine-injected mouse. Considering these findings, pergolide and probably bromocriptine may also protect against dysfunction of dopaminergic neurons because of its multiple effects; not only does it stimulate the presynaptic autoreceptors, but it also directly scavenges • NO radicals and hence protects against • NO-related cytotoxicity. This ESR spectrometry method using carboxy-PTIO may be useful for screening other drugs that can quench • NO. 相似文献
727.
Jun Anzai Fumihiko Takamatsu Kenji Takeuchi Takashi Kohno Kinjiro Morimoto Hideo Goto Nobuyuki Minamoto Akihiko Kawai 《Microbiology and immunology》1997,41(3):229-240
We have investigated a phosphatase-sensitive sequential epitope of the nucleoprotein (N), one of the phosphoproteins of rabies virus, which is recognized by the monoclonal antibody (MAb) #5-2-26. The epitope was shared in common by all of the rabies virus strains we tested, including the HEP, ERA, CVS and Japanese strains (Nishigahara and Komatsukawa). Thin layer chromatography of the acid hydrolyzates of 32P-labeled N protein showed that the protein contained phosphoserine and phospho-threonine at a molar ratio of about 4 to 1, while no phosphotyrosine was detected. Immunoprecipitation studies with several deletion mutants of the N protein showed that the epitope is located in a region spanning from amino acid 344 to 415. If the phosphatase-sensitive epitope is located at or near the phosphoamino acid, the location of the latter could be narrowed further to a region from amino acid 354 to 389 by comparing the amino-acid sequences among the viral strains. To examine this assumption, point mutation was introduced by amino-acid substitution with alanine at either of five potential phosphorylation sites (i.e., positions 354, 375, 377, 386 and 389) in the 354–389 region. Among those, only one substitution, at position 389, greatly affected the antigenicity. Substitution of serine-389 by threonine also reduced the antigenicity. These results strongly suggest that serine-389 is a phosphorylation site and essential for constructing or stabilizing the antigenic structure for MAb 5-2-26. 相似文献
728.
729.
Human-human hybridomas which secrete a human monoclonal antibody (h-MoAb) against hepatitis B virus surface antigen showed growth associated production kinetics. The rate of h-MoAb production rapidly decreased after cell growth was arrested in a perfusion culture, even if the perfusion rate was increased. A continuous suspended-perfusion culture, in which both culture broth and culture supernatant are continuously harvested and the same volume of fresh medium is continuously fed into the reactor, was developed to maintain continuous growing conditions during cultivation. In this culture system, the production of h-MoAb continued for more than 50 days with an average productivity of 5.0 mg/l of working volume/day. A semicontinuous immobilized-perfusion culture in which parts of the cells are repeatedly removed from the immobilized reactor was another useful technique for the long term cultivation of these h-h hybridomas. As an average h-MoAb production rate, 62 mg/l of immobilized-bed volume/day was achieved for 65 days of cultivation using a ceramic matrix reactor, and 327 mg/l/day was achieved over 47 days of cultivation using a hollow fiber reactor equipped with Cultureflo MTM Thus, the antibody productivity per reactor volume per day by the semicontinuous immobilized-perfusion culture was much higher than that of the continuous perfusion culture in an agitation reactor. 相似文献
730.
T Kohno D Kohda M Haruki S Yokoyama T Miyazawa 《The Journal of biological chemistry》1990,265(12):6931-6935
Nonprotein amino acid furanomycin was found to bind with Escherichia coli isoleucyl-tRNA synthetase (IleRS) almost as tightly as the substrate L-isoleucine. The conformation of furanomycin bound to the enzyme was determined by NMR analyses including the transferred nuclear Overhauser effect method. The conformation of IleRS-bound furanomycin was similar to that of L-isoleucine, although the chemical structure of furanomycin is unlike that of L-isoleucine. By E. coli IleRS, E. coli tRNAIle was charged with furanomycin as efficiently as with L-isoleucine. Furthermore, furanomycyl-tRNAIle was bound to polypeptide chain elongation factor Tu as tightly as isoleucyl-tRNAIle. Furanomycin was found to be incorporated into beta-lactamase precursor by in vitro protein biosynthesis. A newly designed amino acid will probably be incorporated into proteins, provided that the new amino acid takes a similar conformation as a protein-constituting amino acid in the active site of an aminoacyl-tRNA synthetase. 相似文献