全文获取类型
收费全文 | 179篇 |
免费 | 14篇 |
国内免费 | 3篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 15篇 |
2012年 | 17篇 |
2011年 | 16篇 |
2010年 | 8篇 |
2009年 | 2篇 |
2008年 | 16篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有196条查询结果,搜索用时 15 毫秒
21.
Herd composition counts (HCC) are commonly used to assess population status in deer. We evaluated the reliability of HCC of sika deer (Cervus nippon Temminck) using repeated counts and by comparing estimated sex ratios and calf-to-female ratios of marked deer on Nakanoshima Island, Hokkaido, Japan between April 1999 and October 2000. Although both total counts and sex and age ratios fluctuated greatly by month, seasonal changes showed a relatively small variance. This suggested that seasonal changes in behavior within sex and age classes contributed to biased ratio estimates obtained from HCC. Route counts should be used as a relative population abundance index with estimates of detection probability, especially for females. Adult sex ratios and age ratios from HCC were unbiased during the rutting season (October–November), and age ratios in spring could be used if yearlings are counted as adults. 相似文献
22.
23.
Takashi Yokochi Izumi Nakashima Nobuo Kato Junpei Asai Soichi Iijima 《Microbiology and immunology》1980,24(10):933-944
The sequence of histological changes in the regional lymph node and other lymphoid organs of mice injected with the capsular polysaccharide of Klebsiella pneumoniae (CPS-K) or bacterial lipopolysaccharide (LPS) was followed. Injection of CPS-K, but not LPS, induced the following characteristic histological changes in the regional lymph node. In the early stage there was a marked decrease in the number of small lymphocytes, accompanied by the appearance of scattered fragmented nuclei and infiltration of polymorphonuclear neutrophilic leukocytes, and in the late stage there was marked proliferation of macrophage-like cells and pyroninophilic cells. Histological changes in the thymus and spleen and changes in cell populations in the bone marrow and peripheral blood after CPS-K injection were essentially the same as after LPS injection. Since CPS-K has a much stronger adjuvant action on antibody response than does LPS, it is suggested that the characteristic histological changes in the regional lymph node after injection of CPS-K are closely related to its extraordinarily strong adjuvant action. 相似文献
24.
25.
26.
Hideaki Takano Yuhei Matsui Junpei Nomura Masahiro Fujimoto Naoto Katsumata Takafumi Koyama 《Bioscience, biotechnology, and biochemistry》2017,81(1):153-164
AmfS, a class III lantipeptide serves as a morphogen in Streptomyces griseus. Here, we constructed a high production system of AmfS in S. griseus. We isolated S. griseus Grd1 strain defective in glucose repression of aerial mycelium formation and found it suitable for the overproduction of AmfS. Two expression vectors carrying the strong and constitutive ermE2 promoter were constructed using a multicopy number plasmid, pIJ702. The use of the Grd1 strain combined with the expression vectors enabled high production of AmfS by S. griseus into its culture broth. The expression system was also effective for the generation of abundant AmfS derived from Streptomyces avermitilis. In addition, site-directed mutagenesis revealed the amino acid residues essential for the morphogen activity of AmfS. These results indicate that the constructed system enables efficient production of class III lantipeptides by Streptomyces. 相似文献
27.
Complex structure of cytochrome c–cytochrome c oxidase reveals a novel protein–protein interaction mode 下载免费PDF全文
Satoru Shimada Kyoko Shinzawa‐Itoh Junpei Baba Shimpei Aoe Atsuhiro Shimada Eiki Yamashita Jiyoung Kang Masaru Tateno Shinya Yoshikawa Tomitake Tsukihara 《The EMBO journal》2017,36(3):291-300
Mitochondrial cytochrome c oxidase (CcO) transfers electrons from cytochrome c (Cyt.c) to O2 to generate H2O, a process coupled to proton pumping. To elucidate the mechanism of electron transfer, we determined the structure of the mammalian Cyt.c–CcO complex at 2.0‐Å resolution and identified an electron transfer pathway from Cyt.c to CcO. The specific interaction between Cyt.c and CcO is stabilized by a few electrostatic interactions between side chains within a small contact surface area. Between the two proteins are three water layers with a long inter‐molecular span, one of which lies between the other two layers without significant direct interaction with either protein. Cyt.c undergoes large structural fluctuations, using the interacting regions with CcO as a fulcrum. These features of the protein–protein interaction at the docking interface represent the first known example of a new class of protein–protein interaction, which we term “soft and specific”. This interaction is likely to contribute to the rapid association/dissociation of the Cyt.c–CcO complex, which facilitates the sequential supply of four electrons for the O2 reduction reaction. 相似文献
28.
Ko Tahara Takashi Yamanoshita Mariko Norisada Isao Hasegawa Hiroyuki Kashima Satohiko Sasaki Katsumi Kojima 《Plant and Soil》2008,307(1-2):167-178
To elucidate the mechanism of the high aluminum (Al) resistance of a Myrtaceae tree, Melaleuca cajuputi Powell, we investigated the responses of root tips to Al and compared them with those of an Al-sensitive species, M. bracteata F. Muell. Roots of seedlings of both species were treated with a calcium solution (pH 4.0) containing 0 or 1 mM AlCl3. After 3 h of Al treatment, inhibition of root elongation and deposition of callose and lignin in root tips, typical signs of Al injury, were induced in M. bracteata but not in M. cajuputi, yet Al accumulation in root tips was similar in both species. These results indicate that internal Al tolerance mechanisms, not Al exclusion mechanisms, are responsible for the Al resistance of M. cajuputi. After 3 h of Al treatment, amount of Al tightly bound to root tips, Al remaining after washing with a desorbing solution, was less in M. cajuputi than in M. bracteata. In M. bracteata, 6 h of Al treatment triggered the accumulation of hydrogen peroxide (H2O2) in root tips despite the upregulation of antioxidant mechanisms, activity of peroxidase and concentration of reduced glutathione. In M. cajuputi, 6 h of Al treatment did not affect the concentration of H2O2, but decreased activity of peroxidase, and increased concentration of reduced glutathione in root tips. These results suggest that the less Al tightly bound to root tips is involved in the suppressing the H2O2 accumulation and the internal Al tolerance in M. cajuputi, and that the H2O2 accumulation or changes in cellular environment that bring about H2O2 accumulation despite the upregulation of antioxidant mechanisms results in Al-induced inhibition of root elongation in M. bracteata. 相似文献
29.
30.
Role of aluminum-binding ligands in aluminum resistance of Eucalyptus camaldulensis and Melaleuca cajuputi 总被引:1,自引:0,他引:1
We investigated the roles of Al-binding ligands in Al exclusion from roots and in internal Al detoxification in roots as Al
resistance mechanisms in two Al-resistant Myrtaceae trees, Eucalyptus camaldulensis Dehnh. and Melaleuca cajuputi Powell. The amounts of ligands secreted from roots and contained in root tips of these species were compared with those of
an Al-sensitive species, Melaleuca bracteata F. Muell., after the roots were exposed to 0 or 1 mM AlCl3 solution. Secretion of well-known ligands (citrate, oxalate, and malate) from roots under Al treatment was low in all species.
However, in E. camaldulensis, the Al-binding capacity of root exudates under Al treatment was considerable and was higher than that in M. bracteata. Gel filtration chromatography revealed that a low-molecular-weight Al-binding ligand was secreted from roots in response
to Al only in E. camaldulensis. On the other hand, the Al-binding capacity of cell sap in root tips under Al treatment was similar for the resistant and
sensitive species. These results suggest that Al exclusion by secretion of the unknown low-molecular-weight Al-binding ligand
from roots contributes to the Al resistance of E. camaldulensis, whereas M. cajuputi has developed Al-resistance mechanisms other than secretion of ligands from roots or concentration of internal ligands in
root tips. 相似文献