全文获取类型
收费全文 | 85940篇 |
免费 | 7116篇 |
国内免费 | 46篇 |
出版年
2023年 | 386篇 |
2022年 | 748篇 |
2021年 | 1410篇 |
2020年 | 1060篇 |
2019年 | 1136篇 |
2018年 | 1718篇 |
2017年 | 1520篇 |
2016年 | 2404篇 |
2015年 | 3439篇 |
2014年 | 3516篇 |
2013年 | 4460篇 |
2012年 | 5666篇 |
2011年 | 5517篇 |
2010年 | 3369篇 |
2009年 | 3085篇 |
2008年 | 4240篇 |
2007年 | 4266篇 |
2006年 | 3843篇 |
2005年 | 4093篇 |
2004年 | 4072篇 |
2003年 | 3545篇 |
2002年 | 3057篇 |
2001年 | 1925篇 |
2000年 | 1767篇 |
1999年 | 1667篇 |
1998年 | 936篇 |
1997年 | 809篇 |
1996年 | 849篇 |
1995年 | 709篇 |
1994年 | 688篇 |
1993年 | 658篇 |
1992年 | 1207篇 |
1991年 | 1035篇 |
1990年 | 1000篇 |
1989年 | 998篇 |
1988年 | 981篇 |
1987年 | 864篇 |
1986年 | 844篇 |
1985年 | 846篇 |
1984年 | 767篇 |
1983年 | 621篇 |
1982年 | 532篇 |
1981年 | 520篇 |
1980年 | 465篇 |
1979年 | 605篇 |
1978年 | 502篇 |
1977年 | 422篇 |
1975年 | 406篇 |
1974年 | 443篇 |
1973年 | 424篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
133.
Production of vanillic acid from vanillin by resting cells of Serratia marcescens. 总被引:2,自引:2,他引:0
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Resting-cell suspensions of Serratia marcescens were able to convert, quantitatively, 0.3% vanillin to vanillic acid. The vanillic acid-producing activity reached a maximum after 28 h of incubation with 0.01% vanillin as an inducer. 相似文献
134.
Wytske de Vries M. I. H. Aleem Anneke Hemrika-Wagner A. H. Stouthamer 《Archives of microbiology》1977,112(3):271-276
Fumarase-free electron particles from Propionibacterium freudenreichii and P. pentosaceum were prepared by discontinuous sucrose gradient centrifugation, and the influence of 2-n-heptyl-4-hydroxy-quinoline-N-oxide (HQNO) and ultraviolet irradiation on the reduction of menaquinone and cytochrome b with l-lactate or glycerol-3-phosphate and the reoxidation by fumarate was studied. In the presence of HQNO the steady state reduction level of menaquinone during fumarate reduction was increased whereas the steady state reduction level of cytochrome b was decreased as compared with the reduction levels measured in the absence of HQNO. The steady state reduction level of menaquinone during electron transport to fumarate was not influenced by ultraviolet irradiation and the steady state reduction level of cytochrome b was decreased at increasing irradiation times. The data indicate that cytochrome b is involved in the electron transport to fumarate.Abbreviations HQNO
2-n-heptyl-4-hydroxyquinoline-N-oxide
- NQNO
2-n-nonyl-4-hydroxyquinoline-N-oxide
Visiting Professor at the Biological Laboratory 相似文献
135.
Oxidation of liposome phospholipids has been studied in the presence of cytochrome c. Sonicated vesicles of soya bean or egg-yolk lipids, or purified phospholipid preparations, were treated with oxidized cytochrome c at a 10:4 lipid/protein ratio (w/w). Lipid peroxidation was examined by oxygen polarography, gas-liquid chromatography (GLC) and the thiobarbituric acid test. Oxidized, but not reduced, cytochrome effectively catalyzes lipid oxidation under these conditions. Oxygen consumption and disappearance of unsaturated fatty acids follow closely similar patterns, the O2 consumption rate showing a maximum (1.53 mol O2/min per mol heme) shortly before fatty acid loss reaches its peak. GLC and O2 consumption data suggest that monohydroperoxides are the most abundant oxidized species in the system. The thiobarbituric acid reaction, however, appears only to be of qualitative value in peroxidation studies. In order to test the mechanism through which oxidation occurs in our system, the effect of liposome composition and the presence of antioxidants was tested, both on cytochrome c binding to bilayers and on O2 consumption. Oxidized and reduced cytochrome c bind the lipid bilayers with similar affinity, but only the oxidized form is active in autoxidation. Antioxidants do not modify either cytochrome c binding to sonicated liposomes. Lipid composition does influence considerably cytochrome binding, and O2 consumption is correspondingly altered. Studies with various antioxidants and inhibitors suggest that both free radicals and singlet oxygen may be involved in the process under study. 相似文献
136.
Caroline van Haaften-Day Peter Russell Susan Carr Lesley Wright 《In vitro cellular & developmental biology. Plant》1988,24(10):965-971
Summary A cell line derived from a human ovarian carcinosarcoma was established in tissue culture and in nude mice. Two sublines,
LDF and HDF, separated by discontinuous density centrifugation were also established from the parent line JoN. The cloning
efficiency of the JoN line was 21%. Morphologic features of adenocarcinoma cells characteristic of the parent JoN cells were
retained in the sublines and clones; all lines showed the same karyotype and DNA content (pseudodiploid and pseudotetraploid).
Keratin, as demonstrated immunohistochemically, was strongly expressed in the parent line JoN and the xenograft tumor, but
not at all in the LDF sublines and only moderately in the HDF sublines. Vimentin, however, was expressed in neither the parent
line JoN nor the xenograft tumor, but was present in both sublines. Transglutaminase and plasminogen activator activity was
high in the parent line JoN. Neither, sublines nor clones showed the same high enzyme activity as the parent line. It is concluded
that this human tumor line JoN is comprised of epithelial cells, capable of multidirectional differentiation. 相似文献
137.
The improvement of glass capillary preparation technology has allowed the development of high-resolution and very low-bleeding gas chromatographic columns. Using an all-glass injector and a flame ionization detector, it was possible to get a complete resolution of some of the principal stable oxygenated metabolites of arachidonic acid (cyclized and aliphatic, i.e., eicosanoids). Due to the low bleeding of the column, detector limits exceed those obtained with previously prepared columns. Total profiling studies have been obtained with small amounts of activated washed platelets after only an ether extraction, allowing for the first time a complete, simultaneous survey of cycloxygenase and lipoxygenase pathways. The application has been extended with success to other cell types. 相似文献
138.
139.
140.
de Haas P. G. 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1947,17(13-15):402-411
Theoretical and Applied Genetics - 相似文献