全文获取类型
收费全文 | 3989篇 |
免费 | 329篇 |
国内免费 | 2篇 |
出版年
2023年 | 16篇 |
2022年 | 23篇 |
2021年 | 64篇 |
2020年 | 39篇 |
2019年 | 44篇 |
2018年 | 80篇 |
2017年 | 52篇 |
2016年 | 86篇 |
2015年 | 156篇 |
2014年 | 169篇 |
2013年 | 199篇 |
2012年 | 252篇 |
2011年 | 279篇 |
2010年 | 167篇 |
2009年 | 147篇 |
2008年 | 226篇 |
2007年 | 214篇 |
2006年 | 230篇 |
2005年 | 199篇 |
2004年 | 227篇 |
2003年 | 189篇 |
2002年 | 206篇 |
2001年 | 75篇 |
2000年 | 58篇 |
1999年 | 64篇 |
1998年 | 48篇 |
1997年 | 40篇 |
1996年 | 37篇 |
1995年 | 42篇 |
1994年 | 25篇 |
1993年 | 26篇 |
1992年 | 43篇 |
1991年 | 40篇 |
1990年 | 30篇 |
1989年 | 31篇 |
1988年 | 36篇 |
1987年 | 28篇 |
1986年 | 17篇 |
1985年 | 28篇 |
1984年 | 27篇 |
1983年 | 21篇 |
1982年 | 36篇 |
1981年 | 34篇 |
1980年 | 19篇 |
1979年 | 26篇 |
1978年 | 28篇 |
1977年 | 26篇 |
1976年 | 18篇 |
1975年 | 19篇 |
1974年 | 21篇 |
排序方式: 共有4320条查询结果,搜索用时 15 毫秒
51.
Selenoprotein P associates with endothelial cells in rat tissues 总被引:11,自引:0,他引:11
R. F. Burk Kristina E. Hill Martha E. Boeglin Ford F. Ebner Harold S. Chittum 《Histochemistry and cell biology》1997,108(1):11-15
Selenoprotein P is an extracellular heparin-binding protein that has been implicated in protecting the liver against oxidant
injury. Its location in liver, kidney, and brain was determined by conventional immunohistochemistry and confocal microscopy
using a polyclonal antiserum. Selenoprotein P is associated with endothelial cells in the liver and is more abundant in central
regions than in portal regions. It is also present in kidney glomeruli associated with capillary endothelial cells. Staining
of selenoprotein P in the brain is also confined to vascular endothelial cells. The heparin-binding properties of selenoprotein
P could be the basis for its binding to tissue. Its localization to the vicinity of endothelial cells is potentially relevant
to its oxidant defense function.
Accepted: 6 March 1997 相似文献
52.
Yoshihisa Iwamoto Yusaku Suzuki Akinobu Kurita Yoko Watanabe Tadayori Shimizu Hirohisa Ohgami Yasutake Yanagihara 《Microbiology and immunology》1995,39(11):831-837
A new species, Vibrio trachuri sp. nov., was isolated from the cultured Japanese horse mackerel (Trachurus japonicus). These Vibrio were Gram negative, motile rods and formed yellow colonies on BTB teepol and TCBS plate, turned TSI medium to yellow and was sensitive to 150 μM O/129 (2,4-diamino-6,7-diisopropyl pteridine phosphate) like Listonella anguillarum which has been described as Vibrio anguillarum. However, the results of VP test and decarboxylation of lysine or dihydrolation of arginine suggested that these Vibrio are rather closely related to V. parahaemolyticus. DNA similarity determined by the microplate hybridization technique revealed that these Vibrio are genetically quite distant from Listonella anguillarum or V. parahaemolyticus and rather close to V. harveyi, although there was no Vibrio species which had more than 70% similarity value. From these results we propose to nominate Vibrio trachuri sp. nov. for this new Vibrio species. 相似文献
53.
The purpose of this investigation was to determine whether Madurella mycetomatis, the most frequent agent of eumycotic mycetomas, produces siderophores and synthesizes new outer membrane proteins under iron-starvation conditions. Siderophore production, only of the hydroxamate type, was demonstrated in all nine strains tested. It was regulated by extracellular iron concentrations. Under iron-restricted conditions, M. mycetomatis expressed various outer membrane iron-regulated proteins, particularly of 24-kilodalton, that may participate in iron metabolism. 相似文献
54.
55.
56.
Summary Sixteen patients with unusual heteromorphisms involving alterations of the length and/or position of centromeric heterochromatin are described. Family studies showed that the heteromorphisms were present in other relatives and segregated in the expected 1:1 ratio. There was a significantly greater frequency of unusual heteromorphisms among Orientals than in other races studied. 相似文献
57.
Crayfish (Cambarus bartoni) were tested individually in an electronic shuttlebox thermoregulatory device which allowed them to control water temperature, and thereby their body temperature, by their movements.Crayfish which initially selected 22.1°C water increased their preferred temperature by 1.8°C following injection of killed bacteria (Aeromonas hydrophila) into the gill cavity.This behavioral fever appears similar to that of vertebrates, and may enhance host defense reactions against pathogens. 相似文献
58.
59.
Tetsuo Omata Noritada Iwamoto Tomio Kimura Atsuo Tanaka Saburo Fukui 《Applied microbiology and biotechnology》1981,11(4):199-204
Summary
dl-Menthyl succinate was successfully hydrolyzed stereoselectively by Rhodotorula minuta var. texensis cells entrapped within photo-crosslinked or polyurethane resin gels in water-saturated n-heptane. The hydrolyzed product was found to be pure l-menthol. The catalytic activity of the immobilized cells, especially those entrapped in urethane polymers, was far more stable than that of the free cells. The half-life of the polyurethaneentrapped cells was estimated to be 55–63 days in the organic solvent.Dedicated to the 65th birthday od Professor Dr. G. Manecke 相似文献
60.
Martha J. Powell 《American journal of botany》1980,67(6):839-853
The structure of centric, intranuclear mitosis and of organelles associated with nuclei are described in developing zoosporangia of the chytrid Rhizophydium spherotheca. Frequently dictyosomes partially encompass the sides of diplosomes (paired centrioles). A single, incomplete layer of endoplasmic reticulum with tubular connections to the nuclear envelope is found around dividing nuclei. The nuclear envelope remains intact during mitosis except for polar fenestrae which appear during spindle incursion. During prophase, when diplosomes first define the nuclear poles, secondary centrioles occur adjacent and at right angles to the sides of primary centrioles. By late metaphase the centrioles in a diplosome are positioned at a 40° angle to each other and are joined by an electron-dense band; by telophase the centrioles lie almost parallel to each other. Astral microtubules radiate into the cytoplasm from centrioles during interphase, but by metaphase few cytoplasmic microtubules are found. Cytoplasmic microtubules increase during late anaphase and telophase as spindle microtubules gradually disappear. The mitotic spindle, which contains chromosomal and interzonal microtubules, converges at the base of the primary centriole. Throughout mitosis the semipersistent nucleolus is adjacent to the nuclear envelope and remains in the interzonal region of the nucleus as chromosomes separate and the nucleus elongates. During telophase the nuclear envelope constricts around the chromosomal mass, and the daughter nuclei separate from each end of the interzonal region of the nucleus. The envelope of the interzonal region is relatively intact and encircles the nucleolus, but later the membranes of the interzonal region scatter and the nucleolus disperses. The structure of the mitotic apparatus is similar to that of the chytrid Phlyctochytrium irregulare. 相似文献