全文获取类型
收费全文 | 307篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
314篇 |
出版年
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 5篇 |
2012年 | 12篇 |
2011年 | 12篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 3篇 |
2007年 | 9篇 |
2006年 | 10篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 12篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 17篇 |
1999年 | 5篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1970年 | 1篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1966年 | 2篇 |
排序方式: 共有314条查询结果,搜索用时 0 毫秒
61.
M. O. Segizbaeva M. A. Pogodin I. N. Lavrova M. V. Balykin N. P. Aleksandrova 《Human physiology》2011,37(2):171-177
The effect of a head-down tilt on the responses of the external respiration system and the functional capacity of the diaphragm
and parasternal muscles were investigated in 11 healthy subjects. A 30-min head-down tilt posture (−30° relative to the horizontal)
significantly increased the inspiratory time, decreased the respiration rate and the inspiratory and expiratory flow rates;
and increased the airway resistance compared to these values in the vertical posture. There were no significant changes in
tidal volume or minute ventilation. The electromyograms (EMGs) of the diaphragm and parasternal muscles showed that the constant
values of tidal volume and minute ventilation during head-down tilt could be provided by an increase in the electric activity
of the thoracic inspiratory muscles. It was established that the contribution of the thoracic inspiratory muscles increased,
while the diaphragms’ contribution decreased, during patient, spontaneous breathing. The maximal inspiratory effort (Muller’s
maneuver) during a head-down tilt evoked the opposite EMG-activity pattern: the contribution of inspiratory thoracic muscles
was decreased and the diaphragm EMG activity was increased compared to the vertical posture. These results suggest that coordinated
modulations in inspiratory muscle activity make it possible to preserve the functional reserve of human inspiratory muscles
during a short-term head-down tilt. 相似文献
62.
Clemens Wittenbecher Romina di Giuseppe Ronald Biemann Juliane Menzel Maria Arregui Juliane Hoffmann Krasimira Aleksandrova Heiner Boeing Berend Isermann Matthias B. Schulze Cornelia Weikert 《PloS one》2015,10(9)
The reliability of single time point measurements of the novel adipokines retinol-binding protein 4 and omentin-1 in the blood has not been evaluated in large samples yet. The present study aimed to assess the amount of biological variation of these two adipokines within individuals. The study sample comprised 207 participants (124 women and 83 men) from Potsdam (Germany) and surrounding areas, with an average age of 56.5 years (SD 4.2). Blood samples were collected from each participant twice, approximately four months apart. Using enzyme linked immunosorbent assays, the concentrations of retinol-binding protein 4 and omentin-1 were determined in EDTA plasma. As indicators of reliability, intraclass correlation coefficients (ICCs) were calculated from the repeated biomarker measurements. The ICCs for repeated retinol-binding protein 4 and omentin-1 measurements were 0.77 (95% CI 0.71, 0.82) and 0.83 (95% CI 0.78, 0.87), respectively, indicating for both adipokines excellent reliability. ICCs were stable across strata according to sex, age, BMI, and blood pressure. Thus, for epidemiological studies it seems reasonable to rely on concentrations of retinol-binding protein 4 and omentin-1 in samples from a single time point if repeated measurements are not available. 相似文献
63.
S. S. Terekhov T. V. Bobik Yu. A. Mokrushina A. V. Stepanova N. M. Aleksandrova I. V. Smirnov A. A. Belogurov N. A. Ponomarenko A. G. Gabibov 《Applied Biochemistry and Microbiology》2016,52(2):162-169
A platform for the cloning and expression of active human butyrylcholinesterase (BuChE) in the yeast Pichia рastoris is first presented. Genetic constructs for BuChE gene expression, separately and in conjunction with a proline-rich peptide called proline-rich attachment domain (PRAD), are based on the vector pPICZαA. It is shown that the highest level of production is achieved in the expression of a BuChE gene without PRAD pPICZαA. It is found that one can obtain up to 125 mg of active enzyme from 1 L of culture medium at an optimal pH environment (pH 7.6), an optical seed culture density of 3 o.u., and an optimum methanol addition mode of (0.5% methanol in the first day and 0.2% thereafter from the second day). 相似文献
64.
65.
66.
67.
D. V. Grishin D. D. Zhdanov Ju. A. Gladilina V. S. Pokrovsky O. V. Podobed M. V. Pokrovskaya S. S. Aleksandrova A. L. Milyushkina M. A. Vigovskiy N. N. Sokolov 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2018,12(2):143-150
In this work, a recombinant chemotaxis CheW protein from Thermotoga petrophila RKU-1 (TpeCheW) and its mutant homologue (TpeCheW-mut) have been obtained. Despite the low homology with the CheW protein of the Escherichia coli bacteria, these proteins do not cause metabolic overload and are well expressed by E. coli laboratory strains. A wide range of features and parameters important for isolation of the TpeCheW-mut protein, such as stability over a wide range of temperatures and pH values, high level of expression, solubility, and the possibility of using simple low-stage purification schemes, including heat pretreatment, has been recognized. Possible directions of using this protein in the practice of scientific and applied research have been formulated and justified. 相似文献
68.
69.
R. Daraktchiev V. Beschkov N. Kolev T. Aleksandrova 《Bioprocess and biosystems engineering》1997,16(2):115-117
The bioreactor with a semi-fixed packing consists of frames with stretched “Raschell”-type sacks on them. This construction enables the attainment of a larger interfacial area of the biofilm carrier per unit reactor volume as well as the easy removal of the exausted biomass at certain biofilm thickness. In the present paper the batch anaerobic conversion of lactose to lactic acid in this reactor with immobilized bacteria Lactobacillus casei is studied. The dilution rate of the feeding substrate solution was 1?mm/s. Comparison of our experimental results with data, obtained for free cells and other construction of bioreactors with immobilized cells is made. It is shown that the used immobilised biocatalyst is superior to free bacterial cells, or attached to the inner pores of polyurethane foam. 相似文献
70.