全文获取类型
收费全文 | 1313篇 |
免费 | 128篇 |
出版年
2021年 | 14篇 |
2019年 | 9篇 |
2018年 | 18篇 |
2017年 | 15篇 |
2016年 | 27篇 |
2015年 | 36篇 |
2014年 | 54篇 |
2013年 | 53篇 |
2012年 | 72篇 |
2011年 | 59篇 |
2010年 | 37篇 |
2009年 | 37篇 |
2008年 | 60篇 |
2007年 | 57篇 |
2006年 | 60篇 |
2005年 | 52篇 |
2004年 | 72篇 |
2003年 | 62篇 |
2002年 | 78篇 |
2001年 | 62篇 |
2000年 | 64篇 |
1999年 | 51篇 |
1998年 | 23篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 7篇 |
1993年 | 14篇 |
1992年 | 39篇 |
1991年 | 27篇 |
1990年 | 20篇 |
1989年 | 19篇 |
1988年 | 24篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 17篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1979年 | 14篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 10篇 |
1975年 | 11篇 |
1974年 | 9篇 |
1973年 | 6篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1970年 | 8篇 |
排序方式: 共有1441条查询结果,搜索用时 359 毫秒
991.
992.
Correction of the nucleotide sequence of the Citrobacter freundii tryptophan operon regulatory region. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We present a correction of the previously reported nucleotide sequence of the Citrobacter freundii trp operon regulatory region. The original sequence analyses were performed with a plasmid designated pCF2. We repeated the cloning of the trp regulatory region of C. freundii and concluded from the determined sequence that a DNA rearrangement had occurred within the leader region of the cloned trp DNA of pCF2. The correct sequence is homologous to the Escherichia coli sequence. 相似文献
993.
Yasushi Oda Ryuji Nakayama Akio Kuroda Junichi Sekiguchi 《Molecular genetics and genomics : MGG》1993,241(3-4):380-388
We have cloned a DNA fragment containing the gene for a cell wall hydrolase from Bacillus licheniformis FD0120 into Escherichia coli. Sequencing of the fragment showed the presence of an open reading frame (ORF; designated as cwlL), which is different from the B. licheniformis cell wall hydrolase gene cwlM, and encodes a polypeptide of 360 amino acids with a molecular mass of 38 994. The enzyme purified from the E. coli clone is an N-acetylmuramoyl-l-alanine amidase, which has a Mr value of 41 kDa as determined by SDS-polyacrylamide gel electrophoresis, and is able to digest B. licheniformis, B. subtilis and Micrococcus luteus cell walls. The nucleotide and deduced amino acid sequences of cwlL are very similar to those of ORF3 in the putative operon xpaL1-xpaL2-ORF3 in B. licheniformis MC14. Moreover, the amino acid sequence homology of CwlL with the B. subtilis amidase CwlA indicates two evolutionarily distinguishable regions in CwlL. The sequence homology of CwlL with other cell wall hydrolases and the regulation of cwlL are discussed. 相似文献
994.
Yasushi Oda Ryuji Nakayama Akio Kuroda Junichi Sekiguchi 《Molecular & general genetics : MGG》1993,241(3-4):380-388
We have cloned a DNA fragment containing the gene for a cell wall hydrolase from Bacillus licheniformis FD0120 into Escherichia coli. Sequencing of the fragment showed the presence of an open reading frame (ORF; designated as cwlL), which is different from the B. licheniformis cell wall hydrolase gene cwlM, and encodes a polypeptide of 360 amino acids with a molecular mass of 38 994. The enzyme purified from the E. coli clone is an N-acetylmuramoyl-l-alanine amidase, which has a Mr value of 41 kDa as determined by SDS-polyacrylamide gel electrophoresis, and is able to digest B. licheniformis, B. subtilis and Micrococcus luteus cell walls. The nucleotide and deduced amino acid sequences of cwlL are very similar to those of ORF3 in the putative operon xpaL1-xpaL2-ORF3 in B. licheniformis MC14. Moreover, the amino acid sequence homology of CwlL with the B. subtilis amidase CwlA indicates two evolutionarily distinguishable regions in CwlL. The sequence homology of CwlL with other cell wall hydrolases and the regulation of cwlL are discussed. 相似文献
995.
996.
Joji Kitayama Nelson Tsuno Hiroshi Yasuhara Hirokazu Nagawa Wataru Kimura Akira Kuroda Yoichi Shibata Takeo Juji Tetsuichiro Muto 《Cancer immunology, immunotherapy : CII》1994,38(5):317-322
The mechanisms of lysis of endothelial cells derived from human umbilical vein (HUVEC) by autologous lymphokine-activated killer (LAK) cells, generated from cord blood lymphocytes of the same donor, were investigated. Freshly isolated HUVEC as well as HUVEC cultured for several passages were efficiently lysed by autologous LAK cells, and their susceptibility to the LAK cells was almost the some as that of allogenic HUVEC. Complement-depletion experiments revealed that the lysis was mainly dependent on CD16-natural killer (NK) LAK cells. Pretreatment of HUVEC with recombinant interferon (rIFN) for 24 h made them resistant to lysis by autologous LAK cells, while pretreatment with either rIL-1. rTNF, or acidic or basic fibroblast growth factor did not alter the lytic sensitivity of HUVEC. The resistance of rIFN-treated HUVEC was specific to lysis by CD16+ NK LAK cells, and their lysis by CD3+ T-LAK cells was not significantly altered. Moreover, in comparison with control HUVEC or rIL-1-treated HUVEC, rIFN-treated HUVEC had a significantly less potent inhibitory effect on the lysis of untreated HUVEC, when used as an unlabeled target. This suggests that rIFN treatment may down-regulate the recognition of some molecules on HUVEC by rIL-2-activated NK cells. These data suggest that damage of the endothelium during LAK therapy is mainly dependent on LAK cells with a NK phenotype that can specifically recognize a certain molecule on autologous endothelial cells. 相似文献
997.
Furuichi Takeshi Idani Gen'ichi Ihobe Hiroshi Kuroda Suehisa Kitamura Koji Mori Akio Enomoto Tomoo Okayasu Naobi Hashimoto Chie Kano Takayoshi 《International journal of primatology》1998,19(6):1029-1043
We analyzed population dynamics and birth seasonality of wild bonobos at Wamba, Democratic Republic of the Congo, based on 20 years of observations (1976–1996). Wamba Bonobo infant mortality is much lower than that reported for chimpanzees. This seemes to be related to several socioecological characteristics of bonobos: the use of abundant fruit and herbaceous foods, larger food patch size, female feeding priority, and the absence of infanticide. The mean interval between live births of 4.8 years is shorter than those reported for chimpanzees, and some females simultaneously carried and nursed two successive offspring. Mother–offspring conflicts, such as refusal of suckling attempts and interference with mothers' copulation, which are common in chimpanzees, are rare in Wamba bonobos. A birth peak seems to occur during the light rainy season from March to May, just after the season with the least rainfall. This timing of births is similar to those reported for chimpanzee populations, and might benefit both mother and offspring by maximizing the amount of time before the next dry season. 相似文献
998.
M. Shimadal M. D. Ph. D. T. Koide E. Kuroda N. Tsuboyama Y. Hosokawa M. Watanabe 《Amino acids》1998,15(1-2):143-150
Summary The expressions of cysteine dioxygenase (CDO) gene in the liver, lung, skeletal muscle, and kidney were studied byin situ hybridization with a cDNA probe from rat liver CDO under normal conditions. Significant expression of the CDO gene was detected in the liver, lung, and kidney, but not skeletal muscle. In the liver, the signal was confined to the cytoplasm of the hepatocytes. Furthermore, the signal was stronger in the periportal than that in the perivenous areas. In the lung, an intensive signal was found in the bronchiolar epithelium. As to the kidney, an intensive signal was observed in the distal convoluted tubules, while no signal was found in the proximal convultions. 相似文献
999.
1000.
Toshiaki Hiramatsu Kazuyo Kodama Teruo Kuroda Tohru Mizushima Tomofusa Tsuchiya 《Journal of bacteriology》1998,180(24):6642-6648
We cloned several genes encoding an Na+/H+ antiporter of Staphylococcus aureus from chromosomal DNA by using an Escherichia coli mutant, lacking all of the major Na+/H+ antiporters, as the host. E. coli cells harboring plasmids for the cloned genes were able to grow in medium containing 0.2 M NaCl (or 10 mM LiCl). Host cells without the plasmids were unable to grow under the same conditions. Na+/H+ antiport activity was detected in membrane vesicles prepared from transformants. We determined the nucleotide sequence of the cloned 7-kbp region. We found that seven open reading frames (ORFs) were necessary for antiporter function. A promoter-like sequence was found in the upstream region from the first ORF. One inverted repeat followed by a T-cluster, which may function as a terminator, was found in the downstream region from the seventh ORF. Neither terminator-like nor promoter-like sequences were found between the ORFs. Thus, it seems that the seven ORFs comprise an operon and that the Na+/H+ antiporter consists of seven kinds of subunits, suggesting that this is a novel type of multisubunit Na+/H+ antiporter. Hydropathy analysis of the deduced amino acid sequences of the seven ORFs suggested that all of the proteins are hydrophobic. As a result of a homology search, we found that components of the respiratory chain showed sequence similarity with putative subunits of the Na+/H+ antiporter. We observed a large Na+ extrusion activity, driven by respiration in E. coli cells harboring the plasmid carrying the genes. The Na+ extrusion was sensitive to an H+ conductor, supporting the idea that the system is not a respiratory Na+ pump but an Na+/H+ antiporter. Introduction of the plasmid into E. coli mutant cells, which were unable to grow under alkaline conditions, enabled the cells to grow under such conditions. 相似文献