首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   367篇
  免费   31篇
  2023年   1篇
  2022年   4篇
  2021年   13篇
  2020年   6篇
  2019年   7篇
  2018年   7篇
  2017年   4篇
  2016年   10篇
  2015年   11篇
  2014年   14篇
  2013年   36篇
  2012年   27篇
  2011年   30篇
  2010年   31篇
  2009年   17篇
  2008年   18篇
  2007年   14篇
  2006年   17篇
  2005年   11篇
  2004年   12篇
  2003年   11篇
  2002年   13篇
  2001年   14篇
  2000年   9篇
  1999年   3篇
  1998年   5篇
  1997年   5篇
  1996年   1篇
  1995年   5篇
  1993年   1篇
  1992年   1篇
  1991年   4篇
  1990年   4篇
  1989年   7篇
  1988年   5篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1982年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1973年   3篇
  1972年   1篇
  1970年   2篇
  1968年   1篇
排序方式: 共有398条查询结果,搜索用时 109 毫秒
391.
Large Hydrophobic Residues (LHR) such as phenylalanine, isoleucine, leucine, methionine and valine play an important role in protein structure and activity. We describe the role of LHR in complete set of protein sequences in 15 different species. That is the distribution of LHR in different proteins of different species is reported. It is observed that the proteins prefer to have 27% of large hydrophobic residues in total and all along the sequence. It is also observed that proteins accumulate more LHR in its active sites. A window analysis on these protein sequences shows that the 27% of LHR is more frequent at window length of 45 amino acids. The influenza virus and P. falciparum show a random distribution of LHR in its proteins compared to other model organisms.  相似文献   
392.
393.
394.
Equine osteochondrosis is a developmental joint disease that is a significant source of morbidity affecting multiple breeds of horse. The genetic variants underlying osteochondrosis susceptibility have not been established. Here, we describe the results of a genome‐wide association study of osteochondrosis using 90 cases and 111 controls from a population of Dutch Warmblood horses. We report putative associations between osteochondrosis and loci on chromosome 3 (BIEC2‐808543; = 5.03 × 10?7) and chromosome 10 (BIEC2‐121323; = 2.62 × 10?7).  相似文献   
395.
Journal of Ethology - Artificial lighting at nights (ALAN) affects behaviour in many animals, especially nocturnal species. However, its effect on frugivorous bats remains less explored, especially...  相似文献   
396.
This study presents ethanol''s fabrication by fermenting the golden trumpet flower (Allamanda schottii L) with the yeast strain Saccharomyces cerevisiae. The changes in different parameters during fermentation were studied and optimized while producing the ethanol and the end product was subjected to emission test study by blending petrol and ethanol. The Allamanda floral substrate contains 65% polysaccharides. The strain S. cerevisiae was obtained in the form of baker’s yeast from a domestic shop. For 100 ml of slurry, the highest bioethanol yield recorded was about 18.75 ml via optimization of different culture conditions, including a 1:8 ratio for slurry preparation, maintained under 35 ⁰C, 5.5 pH, 72 h. old inoculum with a quantity of 3.75 g 100 ml−1, fermented for120 h. The highest yield of bioethanol was acquired under the addition of urea. This technique & design is capable of industrial-scale fabrication of bioethanol by using A. schottii floral substrates. This research was conducted to fabricate ethanol by fermentation (A. schottii L) floral substrate with S. cerevisiae. The optimum physiochemical parameters required to obtain the highest yield of bioethanol from A. schottii flower by fermentation was studied. The immobilization strategy with a cheap agricultural substrate and magnetic nanoparticles were also studied. The engine performance and emission studies were done with different blends of petrol and bio-ethanol.  相似文献   
397.
Ageing influences gait patterns which in turn can affect the balance control of human locomotion. Entropy-based regularity and complexity measures have been highly effective in analysing a broad range of physiological signals. Minimum toe clearance (MTC) is an event during the swing phase of the gait cycle and is highly sensitive to the spatial balance control properties of the locomotor system. The aim of this research was to investigate the regularity and complexity of the MTC time series due to healthy ageing and locomotors' disorders. MTC data from 30 healthy young (HY), 27 healthy elderly (HE) and 10 falls risk (FR) elderly subjects with balance problems were analysed. Continuous MTC data were collected and using the first 500 data points, MTC mean, standard deviation (SD) and entropy-based complexity analysis were performed using sample entropy (SampEn) for different window lengths (m) and filtering levels (r). The MTC SampEn values were lower in the FR group compared to the HY and HE groups for all m and r. The HY group had a greater mean SampEn value than both HE and FR reflecting higher complexity in their MTC series. The mean SampEn values of HY and FR groups were found significantly different for m = 2, 4, 5 and r = (0.1–0.9) × SD, (0.3–0.9) × SD and (0.3–0.9) × SD, respectively. They were also significant difference between HE and FR groups for m = 4–5 and r = (0.3–0.7) × SD, but no significant differences were seen between HY and HE groups for any m and r. A significant correlation of SampEn with SD of MTC was revealed for the HY and HE groups only, suggesting that locomotor disorders could significantly change the regularity or the complexity of the MTC series while healthy ageing does not. These results can be usefully applied to the early diagnosis of common gait pathologies.  相似文献   
398.
Twenty-nine laticiferous taxa of Apocynaceae, Asclepiadaceae, and Sapotaceae were screened for suitability as alternative sources of renewable energy, rubber, and phytochemicals and to select the most promising ones for large-scale cultivation. Of these,Allamanda violacea (14.9% protein, 13.8% polyphenol, 8.6% oil, 3.2% hydrocarbon),Catharanthus roseus (15.4% protein, 10.4% polyphenol, 11.5% oil, 1.9% hydrocarbon), andHolarrhena antidysenterica (14.2% protein, 16.4% polyphenol, 5.4% oil, 4.8% hydrocarbon) of Apocynaceae;Asclepias curassavica (19.3% protein, 6.5% polyphenol, 3.9% oil, 2.0% hydrocarbon), Calotropis gigantea (18.5% protein, 6.8% polyphenol, 7.0% oil, 2.8% hydrocarbon) of Asclepiadaceae;Mimusops elengi (11.3% protein, 9.7% polyphenol, 7.2% oil, 4.0% hydrocarbon) of Sapotaceae show promising potential for future petrochemical plantations; of all these taxa,Holarrhena antidysenterica yielded an unusually high percentage (4.8%) of hydrocarbon fraction followed byMimusops elengi (4.0%). NMR spectra confirmed the presence of cis-polyisoprene in all species studied exceptNerium indicum (white-flowered var.). These data indicate that the majority of the species under investigation may be considered for large-scale cultivation as an alternative source of rubber, intermediate energy, and other phytochemicals.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号