全文获取类型
收费全文 | 1125篇 |
免费 | 55篇 |
出版年
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 18篇 |
2014年 | 22篇 |
2013年 | 81篇 |
2012年 | 65篇 |
2011年 | 68篇 |
2010年 | 37篇 |
2009年 | 38篇 |
2008年 | 50篇 |
2007年 | 45篇 |
2006年 | 45篇 |
2005年 | 68篇 |
2004年 | 48篇 |
2003年 | 56篇 |
2002年 | 58篇 |
2001年 | 29篇 |
2000年 | 29篇 |
1999年 | 28篇 |
1998年 | 18篇 |
1997年 | 17篇 |
1996年 | 15篇 |
1995年 | 17篇 |
1994年 | 18篇 |
1993年 | 16篇 |
1992年 | 27篇 |
1991年 | 14篇 |
1990年 | 18篇 |
1989年 | 11篇 |
1988年 | 18篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 23篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 9篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 4篇 |
排序方式: 共有1180条查询结果,搜索用时 31 毫秒
1.
Shigeo Koyasu Makoto Asada Akio Fukuda Yoshimi Okada 《Journal of molecular biology》1981,153(2):471-475
The mode of polymerization of two species of flagellins, flagellin A and flagellin B, in polar flagella of Caulobacter crescentus was examined. By immunological staining we found that 1 to 1.2 μm of the portion of the flagellar filament proximal to the cell was composed of flagellin B, whereas about 5 μm of the distal portion was composed of flagellin A. This result, together with the previous observation that a flagellin B-less mutant cannot form normal flagella but instead forms stubs in spite of their high level of flagellin A synthesis, indicates that flagellin B is very important for the formation of complete flagella and/or for the initiation of filament formation from the hook. 相似文献
2.
3.
Y Hiraki N Endo M Takigawa A Asada H Takahashi F Suzuki 《Biochimica et biophysica acta》1987,931(1):94-100
Pulsed electromagnetic fields promote healing of delayed united and ununited fractures by triggering a series of events in fibrocartilage. We examined the effects of a pulsed electromagnetic field (recurrent bursts, 15.4 Hz, of shorter pulses of an average of 2 gauss) on rabbit costal chondrocytes in culture. A pulsed electromagnetic field slightly reduced the intracellular cyclic adenosine 3',5'-monophosphate (cAMP) level in the culture. However, it significantly enhanced cAMP accumulation in response to parathyroid hormone (PTH) to 140% of that induced by PTH in its absence, while it did not affect cAMP accumulation in response to prostaglandin E1 or prostaglandin I2. The effect on cAMP accumulation in response to PTH became evident after exposure of the cultures to the pulsed electromagnetic field for 48 h, and was dependent upon the field strength. cAMP accumulation in response to PTH is followed by induction of ornithine decarboxylase, a good marker of differentiated chondrocytes, after PTH treatment for 4 h. Consistent with the enhanced cAMP accumulation, ornithine decarboxylase activity induced by PTH was also increased by the pulsed electromagnetic field to 170% of that in cells not exposed to a pulsed electromagnetic field. Furthermore, stimulation of glycosaminoglycan synthesis, a differentiated phenotype, in response to PTH was significantly enhanced by a pulsed electromagnetic field. Thus, a pulsed electromagnetic field enhanced a series of events in rabbit costal chondrocytes in response to PTH. These findings show that exposure of chondrocytes to a pulsed electromagnetic field resulted in functional differentiation of the cells. 相似文献
4.
Hiroshi Ishii Osamu Nadaoka Yoshimasa Mimura Yoshio Inoue Riichir Chûj 《International journal of biological macromolecules》1989,11(6)
A tetrapetide containing an Aib residue, Boc-Asn-Aib-Thr-Aib-OMe, was synthesized as a peptide model for the N-glycosylation site in N-glycoproteins. Backbone conformation of the peptide and possible intramolecular interaction between the Asn and Thr side chains were elucidated by means of n.m.r. spectroscopy. Temperature dependence of NH proton chemical shift and NOE experiments showed that Boc-Asn-Aib-Thr-Aib-OMe has a tendency to form a β-turn structure with a hydrogen bond involving Thr and Aib4 NH groups. Incorporation of Aib residues in the peptide model promotes folding of the peptide backbone. With folded backbone conformation, carboxyamide protons of the Asn residue are not involved in hydrogen bond network, while the OH group of the Thr residue is a candidate for a hydrogen bond in DMSO-d6 solution. 相似文献
5.
The polymerase chain reaction for Mycoplasma pulmonis 总被引:2,自引:0,他引:2
R Harasawa K Koshimizu T Uemori O Takeda K Asada I Kato 《Microbiology and immunology》1990,34(4):393-395
In vitro DNA amplification by polymerase chain reaction was examined to detect Mycoplasma pulmonis. A pair of synthetic oligonucleotide primers was constructed, and used to amplify a unique sequence of M. pulmonis DNA. Amplified products were detected by agarose gel electrophoresis and verified by blot hybridization with a synthetic oligonucleotide probe. This system detected cellular DNA of M. pulmonis but not M. arthritidis or M. neurolyticum, and thus appears to be useful for M. pulmonis diagnosis. 相似文献
6.
Summary Electron microscopic studies revealed that major cytological changes in the cortical cells of poplar (Populus euramericana cv. gelrica) began to occur in early September in conjunction with the metabolic transition from the growing to the wintering stage. During this transition, the cells became temporarily rich in endoplasmic reticulum, polysomes and vesicles. As the conspicuous formation of organelles progressed, the large vacuoles became smaller and filled with osmiophilic materials. Undefined organelles (protein-lipid bodies) also increased in number. From late October until March, organelles involved in protein synthesis were sparsely distributed in the cells, indicating that the number of these organelles is probably linked to the seasonal cycle of protein synthesis. In early February, after release from dormancy, fusion of vacuoles proceeded in the cells. The inclusion of organelles and a gradual decrease in the amount of osmiophilic materials in the vacuoles occurred at this stage. Subsequently, the structure of the cells continued to undergo changes to accommodate growth, which occurred in early May. 相似文献
7.
Yasuhiko Asada Yoshio Kimura Masaaki Kuwahara Akira Tsukamoto Kazuo Koide Atsuhiro Oka Mitsuru Takanami 《Applied microbiology and biotechnology》1988,29(5):469-473
Summary A ligninase gene has been cloned from a Phanerochaete chrysosporium genomic DNA library. Nucleotide sequencing of the gene has revealed that the ligninase structural gene contains 1116 bp of the protein-encoding sequence, of which 84 bp encode the signal peptide. The protein-encoding sequence is interrupted by eight introns which conform to the universal G-T/A-G splicing rule observed for the 3 and 5 intron boundaries. The putative eukaryotic regulatory sequences, i.e. CAAT and TATA box-like sequences, are present in the 5 flanking region. 相似文献
8.
Morikawa Hiromichi; Hayashi Yasuyuki; Hirabayashi Yasuzi; Asada Masanori; Yamada Yasuyuki 《Plant & cell physiology》1988,29(1):189-193
Protoplasts isolated from cultured cells of Coptis japonicaand Euphorbia millii were electrically fused using platinummicroelectrodes. The process involved two stages, cellular andvacuolar fusion, which are characterized respectively by transientwrinkling of the membrane and the formation of a dark-red precipitate. (Received June 12, 1987; Accepted October 13, 1987) 相似文献
9.
The effects of three physical parameters upon protoplast electrofusionwere studied using protoplasts from cultured cells of Coptisjaponica and Euphorbia millii. The osmotic potential of themedium did not appreciably affect the AC-field-induced protoplast-pairformation, but significantly influenced the fusion process ofthe paired protoplasts in response to DC pulses. The optimumosmotic potential was 0.55 to 0.60 Osm/kg H2O in our system.The density of the medium markedly influenced both pair formationand fusion process. The optimum density was 1.13 to 1.14 g/cm3,and at this density the yield of the fused protoplasts increasedto more than twice that of the control (1.10 g/cm3). Hydrophiliccoating of the bottom surface of the chamber with Gellan gumor polyacrylamide gel was also effective for both pair formationand the fusion process, while coating with hydrophobic siliconewas entirely inhibitory. Possible interpretations of the effectsof these physical parameters upon protoplast electrofusion arepresented.
1Permanent address: Biochemical Research Laboratories, KanegafuchiChemical Industry Co., Ltd., Takasago, Hyogo 676, Japan. (Received December 21, 1987; Accepted March 18, 1988) 相似文献
10.
Toshio Shimada Dr. Yoshimasa Kosako Yasunori Isshiki Kazuhito Hisatsune 《Current microbiology》1992,25(4):215-217
The O antigen of enterohemorrhagicEscherichia coli O157:H7 is identical with that ofSalmonella O301 and is also related toSalmonella O301302 in an a-a, b type of relationship. 相似文献