全文获取类型
收费全文 | 1190篇 |
免费 | 88篇 |
出版年
2023年 | 13篇 |
2022年 | 24篇 |
2021年 | 27篇 |
2020年 | 25篇 |
2019年 | 18篇 |
2018年 | 36篇 |
2017年 | 27篇 |
2016年 | 31篇 |
2015年 | 33篇 |
2014年 | 58篇 |
2013年 | 78篇 |
2012年 | 103篇 |
2011年 | 72篇 |
2010年 | 38篇 |
2009年 | 35篇 |
2008年 | 40篇 |
2007年 | 63篇 |
2006年 | 39篇 |
2005年 | 38篇 |
2004年 | 46篇 |
2003年 | 39篇 |
2002年 | 49篇 |
2001年 | 35篇 |
2000年 | 38篇 |
1999年 | 34篇 |
1997年 | 9篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 22篇 |
1991年 | 12篇 |
1990年 | 17篇 |
1989年 | 8篇 |
1988年 | 17篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1973年 | 4篇 |
1971年 | 3篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1967年 | 5篇 |
排序方式: 共有1278条查询结果,搜索用时 31 毫秒
121.
A series of ferrocene-containing collagen models Fc-CO-(Pro-Hyp-Gly)n-Cys (n = 4 (1), 6 (2), 7 (3), 8 (4), 9 (5)) were synthesized by solid-phase synthesis. Biophysical studies using circular dichroism (CD) show that these collagen analogues form triple-helical conformations, and the peptides showed a range of thermal stabilities ((T(m)), 38-74 degrees C). Results also indicate that the ferrocene (Fc)-labeled collagen models possesses a higher triple-helical propensity than the unlabeled collagen models as demonstrated by the higher melting temperatures and thermodynamic parameters, and we conclude that the Fc group at the N-terminal position of the peptide strands increases the stability of the triple helix. 相似文献
122.
Gene-expression strategies are remodeled following exposure to stress. The reactive oxidants and electrophiles generated after stress actually affects the structural and functional properties of different cellular proteins. It is also seen that lysine rich motifs of proteins play crucial role in electrophilic attack and modification. Therefore, this study revealing lysine richness in 5 main human snrups (Small Nuclear Ribonucleoproteins) indicates a possible mechanism of gene regulation under stress. This possibility is highly supported by the findings that surface residues of the molecules were full of lysine rich clusters. Lysine richness is also found to be a highly conserved pattern across the various domains of life indicative of stress adaptation in the prebiotic to biotic world transition. Moreover the modeled structures showed good all atom contacts and minimal outliers. 相似文献
123.
Kaur A Singh R Dey CS Sharma SS Bhutani KK Singh IP 《Indian journal of experimental biology》2010,48(3):314-317
Hexane, chloroform and ethyl acetate extracts (100 microg/ml) of Alpinia galanga rhizomes exhibited significant activity in vitro against promastigotes of L. donovani. Twelve compounds namely, methyleugenol (1), p-coumaryl diacetate (2), 1'-acetoxychavicol acetate (3), 1'-acetoxyeugenol acetate (4), trans-p-acetoxycinnamyl alcohol (5), trans-3,4-dimethoxycinnamyl alcohol (6), p-hydroxybenzaldehyde (7), p-hydroxycinnamaldehyde (8), trans-p-coumaryl alcohol (9), galangin (10), trans-p-coumaric acid (11) and galanganol B (12) were isolated from these extracts. Of these, compounds 2, 3, 4 and 5 were found most active in vitro against promastigotes of L. donovani with IC50 values of 39.3, 32.9, 18.9 and 79.9 microM respectively. This is the first report of antileishmanial activity of the extracts and isolated constituents of A. galanga. 相似文献
124.
The surface activity and self-assembly behavior of zwitterionic amphiphile N-(2-hydroxydodecyl)-l-histidine (C12HHis) were studied in phosphate buffers of pH 2 and 13 using surface tension and fluorescence probe techniques, respectively. Transmission electron microscopic images of the aggregates have revealed existence of nano-size vesicles in dilute solutions of both acidic and basic pH. In basic medium, the vesicles are converted to tubular aggregates upon increase of surfactant concentration. The nanotubes undergo phase transition to form elongated or small rod-like micelles at a much higher concentration of the amphiphile. The vesicles and nanotubes were found to become more stable upon addition of 10 mol% of cholesterol. 相似文献
125.
This study describes a novel isolation procedure for major glycolipids from Bifidobacterium adolescentis 94 BIM. The procedure consists of the use of supercritical carbon dioxide (scCO(2)) with hydro-methanolic solution as co-solvent. The major glycolipids were isolated using the following operating conditions: pressure, 30 MPa, co-solvent concentration, 10% (9:1, methanol/water, v/v), CO(2) flow rate, 5 g/min, extraction time and temperature, 2h and 55 degrees C, respectively. The reference glycolipids sample was prepared by classical organic solvent extraction followed by chromatographic purification. All isolates were characterized by TLC and the major glycolipids additionally by enzyme linked immunosorbent (ELISA). Sixty milligrams of glycolipids with similar immunoreactivity as the reference glycolipids were isolated from 1g of freeze-dried biomass (6% of yield). 相似文献
126.
127.
128.
S-adenosyl-L-methionine (AdoMet, 1mM) protects the stationary phase cells of Saccharomyces cerevisiae against the killing effect of acid (10mM HCl, pH approximately 2). Both the acid and the acid plus AdoMet treatment for 2h increased the plasma membrane H(+)-ATPase activity; thereafter it decreased to the basal level. AdoMet partially recovered the intracellular pH (pH(in)) that dropped in presence of acid. AdoMet treatment facilitated acid induced phospholipid biosynthesis as well as membrane proliferation, which was reflected in the cellular lipid composition. 相似文献
129.
Brd4 is required for recovery from antimicrotubule drug-induced mitotic arrest: preservation of acetylated chromatin
下载免费PDF全文
![点击此处可从《Molecular biology of the cell》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The mammalian bromodomain protein Brd4 interacts with mitotic chromosomes by binding to acetylated histone H3 and H4 and is thought to play a role in epigenetic memory. Mitotic cells are susceptible to antimicrotubule drugs. These drugs activate multiple response pathways and arrest cells at mitosis. We found that Brd4 was rapidly released from chromosomes upon treatment with antimicrotubule drugs, including the reversible agent nocodazole. Yet, when nocodazole was withdrawn, Brd4 was reloaded onto chromosomes, and cells proceeded to complete cell division. However, cells in which a Brd4 allele was disrupted (Brd4+/-), and expressing only half of the normal Brd4 levels, were defective in reloading Brd4 onto chromosomes. Consequently, Brd4+/- cells were impaired in their ability to recover from nocodazole-induced mitotic arrest: a large fraction of +/- cells failed to reach anaphase after drug withdrawal, and those that entered anaphase showed an increased frequency of abnormal chromosomal segregation. The reloading defect observed in Brd4+/- cells coincided with selective hypoacetylation of lysine residues on H3 and H4. The histone deacetylase inhibitor trichostatin A increased global histone acetylation and perturbed nocodazole-induced Brd4 unloading. Brd4 plays an integral part in a cellular response to drug-induced mitotic stress by preserving a properly acetylated chromatin status. 相似文献
130.