全文获取类型
收费全文 | 246篇 |
免费 | 6篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 6篇 |
2012年 | 13篇 |
2011年 | 16篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 15篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 16篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有252条查询结果,搜索用时 890 毫秒
1.
L I Kulikova G A Iatskiavichiute V S Tsvetkov Iu E Ershikova S P Gordienko 《Biulleten' eksperimental'no? biologii i meditsiny》1987,104(8):224-226
Antibodies to calcitonin, parathyroid hormone and cortisol are detected in acute stage of infection-caused bronchial asthma. The appearance of antibodies is paralleled by marked hypercalcaemia. The antibodies may bind excessive hormones in the blood, preventing further hormonal imbalance. Ten-day treatment with glucocorticoids decreased the amount of antibodies possibly due to normalization of hormonal secretion and restoration of their balance. As a result, calcium blood levels returned to normal. 相似文献
2.
Conformational changes in DNA G-quadruplex (GQ)-forming regions affect genome function and, thus, compose an interesting research topic. Computer modelling may yield insight into quadruplex folding and rearrangement, particularly molecular dynamics simulations. Here, we show that specific parameters, which are distinct from those commonly used in DNA conformational analyses, must be introduced for adequate interpretation and, most importantly, convenient visual representation of the quadruplex modelling results. We report a set of parameters that comprehensively and systematically describe GQ geometry in dynamics. The parameters include those related to quartet planarity, quadruplex twist, and quartet stacking; they are used to quantitatively characterise various types of quadruplexes and rearrangements, such as quartet distortion/disruption or deviation/bulging of a single nucleotide from the quartet plane. Our approach to describing conformational changes in quadruplexes using the new parameters is exemplified by telomeric quadruplex rearrangement, and the benefits of applying this approach to analyse other structures are discussed. 相似文献
3.
Effect of trehalose on the phase properties of hydrated and lyophilized dipalmitoylphosphatidylcholine multilayers 总被引:3,自引:0,他引:3
The structure and thermal behavior of hydrated and lyophilized dipalmitoylphosphatidylcholine (DPPC) multilayers in the presence of trehalose were investigated by differential scanning calorimetry and X-ray diffraction methods. Trehalose enters the aqueous space between hydrated bilayers and increases the interbilayer separation (from 0.36 to 1.37 nm in the different DPPC phases at 1 M trehalose). It does not affect the lipid chain packing and also the slow isothermal conversion at 4 degrees C of the metastable L beta' phase into the equilibrium crystalline Lc phase. Addition of trehalose leads to a slight upward shift (about 1 degrees C at 1 M trehalose) of the three phase transitions (sub-, pre-, and main transition) in fully hydrated DPPC while their other properties (enthalpy, excess specific heat, and transition width) remain unchanged. The effect of trehalose on the thermal behavior of DPPC multilayers freeze-dried from an initially completely hydrated state is qualitatively similar to that of water. These data support the "water replacement" hypothesis about trehalose action. It is suggested that trehalose prevents the formation of direct interbilayer hydrogen bonds in states of low hydration. 相似文献
4.
5.
The ovaries of 24 ground squirrels (Citellus citellus L) were studied in spring (March, April), summer (July), and winter (December). The animals hibernated in a chamber at a temperature of 6-8 degrees C. The activities of the interstitial gland, theca interna, atretic follicles with theca interna and yellow bodies were measured densitometrically and studied by a specially modified histoenzymatic technique. Measurements showed that the endocrine structures were most active in March and least active in July. The atretic follicles had the highest enzymatic activity in April. The quantitative histoenzymatic approach presents an objective base for morphofunctional studies of organs and tissues at different body temperature levels in hibernators. 相似文献
6.
The Freezing Points of three lactobacilli strains cultivated in skim milk and MRS-broth were determined. Their survival was analyzed after lyophilization. A maximal preservation of the cell number of the R1 strain was found. The fermentation activity of the laclobacilli was investigated before and after lyophilization in order to characterize their species identification. Copyright 1993, 1999 Academic Press. 相似文献
7.
8.
9.
Gang Fan Mario Kaßmann Yingqiu Cui Claudia Matthaeus Sverine Kunz Cheng Zhong Shuai Zhu Yu Xie Dmitry Tsvetkov Oliver Daumke Yu Huang Maik Gollasch 《Aging cell》2020,19(4)
Caveolae position CaV3.2 (T‐type Ca2+ channel encoded by the α‐3.2 subunit) sufficiently close to RyR (ryanodine receptors) for extracellular Ca2+ influx to trigger Ca2+ sparks and large‐conductance Ca2+‐activated K+ channel feedback in vascular smooth muscle. We hypothesize that this mechanism of Ca2+ spark generation is affected by age. Using smooth muscle cells (VSMCs) from mouse mesenteric arteries, we found that both Cav3.2 channel inhibition by Ni2+ (50 µM) and caveolae disruption by methyl‐ß‐cyclodextrin or genetic abolition of Eps15 homology domain‐containing protein (EHD2) inhibited Ca2+ sparks in cells from young (4 months) but not old (12 months) mice. In accordance, expression of Cav3.2 channel was higher in mesenteric arteries from young than old mice. Similar effects were observed for caveolae density. Using SMAKO Cav1.2?/? mice, caffeine (RyR activator) and thapsigargin (Ca2+ transport ATPase inhibitor), we found that sufficient SR Ca2+ load is a prerequisite for the CaV3.2‐RyR axis to generate Ca2+ sparks. We identified a fraction of Ca2+ sparks in aged VSMCs, which is sensitive to the TRP channel blocker Gd3+ (100 µM), but insensitive to CaV1.2 and CaV3.2 channel blockade. Our data demonstrate that the VSMC CaV3.2‐RyR axis is down‐regulated by aging. This defective CaV3.2‐RyR coupling is counterbalanced by a Gd3+ sensitive Ca2+ pathway providing compensatory Ca2+ influx for triggering Ca2+ sparks in aged VSMCs. 相似文献
10.
Milov AD Tsvetkov YD Gorbunova EY Mustaeva LG Ovchinnikova TV Handgraaf JW Raap J 《化学与生物多样性》2007,4(6):1243-1255
Zervamicin is a voltage-gated ion-channel-forming peptide. Channels are generally considered to be formed by first insertion of amphipathic molecules into the phospholipid bilayer, followed by self-assembly of a variable number of transmembrane helices. We have studied the length of the peptide structure to address the question whether this peptide is long enough to span the phospholipid bilayer. The pulsed electron-electron double resonance (PELDOR) spectroscopic technique was used to determine the length of the helical molecule in membrane-mimicking solvents. This was achieved from the distance-related dipole-dipole interaction between spin labels, which were located at both ends of the linear peptide chain. The data were obtained by using samples of frozen glassy solutions of MeOH, MeOH/toluene, and MeOH/CHCl(3). Contributions of inter- and intramolecular interactions of spin labels were separated to analyze the intramolecular interaction and the distance distribution function between the labels. It is shown that the main maximum of the distribution functions is located at a distance of ca. 3.3 nm, and this distance appears to be only slightly dependent on the solvent composition. The distribution function was observed to narrow after addition of either CHCl(3) or toluene to MeOH. This effect is rationalized in terms of a decreased mobility of the terminal amino acid residues. By molecular-dynamics simulations, it was shown that the conformation, corresponding with the predominant distance found by PELDOR, agrees well with the mixed alpha/3(10)-helical that was previously determined by NMR. However, in the case toluene was added to the MeOH solution to further increase the hydrophobicity of the environment of the membrane-active peptide, the distribution function gives rise to a minor fraction (7-8%) with a distance of 4.2 nm. This distance corresponds most likely to the more extended 2(7)-helix structure. 相似文献