全文获取类型
收费全文 | 446篇 |
免费 | 35篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 5篇 |
2019年 | 15篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 14篇 |
2015年 | 22篇 |
2014年 | 32篇 |
2013年 | 28篇 |
2012年 | 30篇 |
2011年 | 34篇 |
2010年 | 26篇 |
2009年 | 17篇 |
2008年 | 24篇 |
2007年 | 29篇 |
2006年 | 26篇 |
2005年 | 18篇 |
2004年 | 21篇 |
2003年 | 7篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1963年 | 1篇 |
1960年 | 2篇 |
1957年 | 1篇 |
1948年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有481条查询结果,搜索用时 15 毫秒
341.
Fermentation and purification strategies for the production of betulinic acid and its lupane‐type precursors in Saccharomyces cerevisiae 下载免费PDF全文
342.
Pharmacophore mapping studies were undertaken for a series of molecules belonging to pyrrolopyrimidines, indolopyrimidines
and their congeners as multidrug resistance-associated protein (MRP1) modulators. A five-point pharmacophore with two hydrogen
bond acceptors (A), one lipophilic/hydrophobic group (H), one positive ionic feature (P) and one aromatic ring (R) as pharmacophoric
features was developed. The pharmacophore hypothesis yielded a statistically significant 3D-QSAR model, with a correlation
coefficient of r
2 = 0.799 for training set molecules. The model generated showed excellent predictive power, with a correlation coefficient Q
2 = 0.679 for an external test set of 20 molecules. The pharmacophore was further validated using four structurally diverse
compounds with MRP1 modulatory activity. These compounds mapped well onto four of the five features of the pharmacophore.
The pharmacophore proposed here was then utilised for the successful retrieval of active molecules with diverse chemotypes
from database search. The geometry and features of pharmacophore are expected to be useful for the design of selective MRP1
inhibitors.
Figure Alignment of multidrug resistance-associated protein (MRP1) inhibitors with the developed pharmacophore.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
343.
Anwaar Ahmad Heng Zhong Wengling Wang Mariam B. Sticklen 《In vitro cellular & developmental biology. Plant》2002,38(2):163-167
Summary We report a less genotype-dependent in vitro regeneration system capable of producing multiple shoot clumps and whole plants in four different wheat genotypes. Shool
apical meristems from 7-d-old-seedlings produced axillary and adventitious shoots and somatic embryos on media containing
N6-benzyladenine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D). All four genotypes responded positively to shoot multiplication
depending upon media composition. Scanning electron microscopies of cultures showed a proliferating budding state that gave
rise to adventitious shoots and somatic embryos on further multiplication. The percentage of relative shoot apical meristem
multiplication was 80–90%, and the average number of shoot meristems per multiplied shoot was 40–50 in all genotypes. Among
different concentrations of phytohormones, 2 and 4 mgl−1 BA (8.8 and 17.7 μM) in combination with 0.5 mg l−1 2,4-D (2.26 μM) gave the best results. Actively multiplying shoot clumps were recovered with high frequency among 3-mo.-old cultures. These
shoot clumps regenerated normally and produced fertile plants containing viable seeds. This in vitro system might prove useful for the production of transgenic plants of wheat in a relatively genotype-independent manner. 相似文献
344.
345.
Zhan Qi Christophe Jung Peter Bandilla Claudia Ludwig Mark Heron Anja Sophie Kiesel Mariam Museridze Julia PhilippouMassier Miroslav Nikolov Alessio Renna Max Schnepf Ulrich Unnerstall Stefano Ceolin Bettina Mühlig Nicolas Gompel Johannes Soeding Ulrike Gaul 《Molecular systems biology》2022,18(2)
The core promoter plays a central role in setting metazoan gene expression levels, but how exactly it “computes” expression remains poorly understood. To dissect its function, we carried out a comprehensive structure–function analysis in Drosophila. First, we performed a genome‐wide bioinformatic analysis, providing an improved picture of the sequence motifs architecture. We then measured synthetic promoters’ activities of ~3,000 mutational variants with and without an external stimulus (hormonal activation), at large scale and with high accuracy using robotics and a dual luciferase reporter assay. We observed a strong impact on activity of the different types of mutations, including knockout of individual sequence motifs and motif combinations, variations of motif strength, nucleosome positioning, and flanking sequences. A linear combination of the individual motif features largely accounts for the combinatorial effects on core promoter activity. These findings shed new light on the quantitative assessment of gene expression in metazoans. 相似文献
346.
Mariam Sahrawy Valérie Hecht Javier Lopez-Jaramillo Ana Chueca Yvette Chartier Yves Meyer 《Journal of molecular evolution》1996,42(4):422-431
In contrast to prokaryotes, which typically possess one thioredoxin gene per genome, three different thioredoxin types have
been described in higher plants. All are encoded by nuclear genes, but thioredoxins m and f are chloroplastic while thioredoxins
h have no transit peptide and are probably cytoplasmic. We have cloned and sequencedArabidopsis thaliana genomic fragments encoding the five previously described thioredoxins h, as well as a sixth gene encoding a new thioredoxin
h. In spite of the high divergence of the sequences, five of them possess two introns at positions identical to the previously
sequenced tobacco thioredoxin h gene, while a single one has only the first intron. The recently published sequence ofChlamydomonas thioredoxin h shows three introns, two at the same positions as in higher plants. This strongly suggests a common origin
for all cytoplasmic thioredoxins of plants and green algae. In addition, we have cloned and sequenced pea DNA genomic fragments
encoding thioredoxins m and f. The thioredoxin m sequence shows only one intron between the regions encoding the transit peptide
and the mature protein, supporting the prokaryotic origin of this sequence and suggesting that its association with the transit
peptide has been facilitated by exon shuffling. In contrast, the thioredoxin f sequence shows two introns, one at the same
position as an intron in various plant and animal thioredoxins and the second at the same position as an intron in thioredoxin
domains of disulfide isomerases. This strongly supports the hypothesis of a eukaryotic origin for chloroplastic thioredoxin
f. 相似文献
347.
The last decade has witnessed a tremendous rise in the proposed applications of nanomaterials in the field of medicine due to their very attractive physiochemical properties and novel actions such as the ability to reach previously inaccessible targets such as brain. However biological activity of functional molecules bound to nanoparticles and its physiological consequences is still unclear and hence this area requires immediate attention. The functional properties of Human Serum Albumin (HSA) and Bovine Serum Albumin (BSA) bound to silver nanoparticles (~60 nm) have been studied under physiological environment. Esterase activity, binding of drugs (warfarin and ibuprofen), antioxidant activity and copper binding by albumins was evaluated. The catalytic efficiencies of HSA and BSA diminished upon binding to silver nanoparticles. Perturbation in binding of warfarin and ibuprofen, loss of free sulphydryls, antioxidant activity and enhancement of copper binding were observed in albumins bound to nanoparticles. These alterations in functional activity of nanoparticle bound albumins which will have important consequences should be taken into consideration while using nanoparticles for diagnostic and therapeutic purposes. 相似文献
348.
Mitchell J. L. Morton Mariam Awlia Nadia Al‐Tamimi Stephanie Saade Yveline Pailles Snia Negro Mark Tester 《The Plant journal : for cell and molecular biology》2019,97(1):148-163
Salt stress limits the productivity of crops grown under saline conditions, leading to substantial losses of yield in saline soils and under brackish and saline irrigation. Salt tolerant crops could alleviate these losses while both increasing irrigation opportunities and reducing agricultural demands on dwindling freshwater resources. However, despite significant efforts, progress towards this goal has been limited, largely because of the genetic complexity of salt tolerance for agronomically important yield‐related traits. Consequently, the focus is shifting to the study of traits that contribute to overall tolerance, thus breaking down salt tolerance into components that are more genetically tractable. Greater consideration of the plasticity of salt tolerance mechanisms throughout development and across environmental conditions furthers this dissection. The demand for more sophisticated and comprehensive methodologies is being met by parallel advances in high‐throughput phenotyping and sequencing technologies that are enabling the multivariate characterisation of vast germplasm resources. Alongside steady improvements in statistical genetics models, forward genetics approaches for elucidating salt tolerance mechanisms are gaining momentum. Subsequent quantitative trait locus and gene validation has also become more accessible, most recently through advanced techniques in molecular biology and genomic analysis, facilitating the translation of findings to the field. Besides fuelling the improvement of established crop species, this progress also facilitates the domestication of naturally salt tolerant orphan crops. Taken together, these advances herald a promising era of discovery for research into the genetics of salt tolerance in plants. 相似文献
349.
Kanakeswary Krishnan Jeremy Er An Ker Shar Mariam Mohammed Vishna Devi Nadarajah 《Journal of biomedical science》2010,17(1):86