全文获取类型
收费全文 | 6587篇 |
免费 | 430篇 |
国内免费 | 11篇 |
专业分类
7028篇 |
出版年
2024年 | 20篇 |
2023年 | 78篇 |
2022年 | 268篇 |
2021年 | 384篇 |
2020年 | 146篇 |
2019年 | 180篇 |
2018年 | 271篇 |
2017年 | 178篇 |
2016年 | 260篇 |
2015年 | 392篇 |
2014年 | 381篇 |
2013年 | 484篇 |
2012年 | 482篇 |
2011年 | 462篇 |
2010年 | 281篇 |
2009年 | 234篇 |
2008年 | 274篇 |
2007年 | 288篇 |
2006年 | 229篇 |
2005年 | 179篇 |
2004年 | 176篇 |
2003年 | 137篇 |
2002年 | 136篇 |
2001年 | 94篇 |
2000年 | 70篇 |
1999年 | 54篇 |
1998年 | 39篇 |
1997年 | 34篇 |
1996年 | 28篇 |
1995年 | 29篇 |
1994年 | 24篇 |
1993年 | 24篇 |
1992年 | 54篇 |
1991年 | 39篇 |
1990年 | 50篇 |
1989年 | 47篇 |
1988年 | 37篇 |
1987年 | 30篇 |
1986年 | 34篇 |
1985年 | 29篇 |
1984年 | 38篇 |
1983年 | 33篇 |
1982年 | 32篇 |
1981年 | 34篇 |
1980年 | 40篇 |
1979年 | 18篇 |
1978年 | 27篇 |
1977年 | 19篇 |
1974年 | 22篇 |
1973年 | 20篇 |
排序方式: 共有7028条查询结果,搜索用时 11 毫秒
281.
Imane Sabaouni Ahmed Moussa Brigitte Vannier Oussama Semlali Terri A Pietka Nada A Abumrad Azeddine Ibrahimi 《Bioinformation》2013,9(17):849-852
We have previously shown that CD36 is a membrane protein that facilitates long chain fatty acid (FA) transport by muscle tissues.
We also documented the significant impact of muscle CD36 expression on heart function, skeletal muscle insulin sensitivity as well
as on overall metabolism. To identify a comprehensive set of genes that are differentially regulated by CD36 expression in the
heart, we used two microarray technologies (Affymetrix and Agilent) to compare gene expression in heart tissues from CD36
KnocK-Out (KO-CD36) versus wild type (WT-CD36) mice. The obtained results using the two technologies were similar with
around 35 genes differentially expressed using both technologies. Absence of CD36 led to down-regulation of the expression of
three groups of genes involved in pathways of FA metabolism, angiogenesis/apoptosis and structure. These data are consistent
with the fact that the CD36 protein binds FA and thrombospondin 1 invoved respectively in lipid metabolism and anti-angiogenic
activities. In conclusion, our findings led to validate our data analysis workflow and identify specific pathways, possibly
underlying the phenotypic abnormalities in CD36 Knock -Out hearts. 相似文献
282.
283.
Fakhriya S. Taha Ahmed S. El-Nockrashy 《Bioscience, biotechnology, and biochemistry》2013,77(11):2625-2629
Three different treatments were tested for their effectiveness in removing alkaloids, and producing protein products suitable for human consumption from Lupinus albus seeds. The treatments included: a) water leaching of the seeds, b) ammonium salt treatment of the seeds, and c) multistage extraction of the defatted meal.Results revealed that treatments a) and c) were highly effective in the removal of alkaloids. Protein contents of the resulting three products were about 62, 47 and 58%, respectively, compared to 39% in the seed. Amino acid analysis showed that the protein preparations lack sulphur amino acids, lysine, tryptophan and valine. 相似文献
284.
285.
Aspergillus terreus MTCC 11096 isolated from the soils of agricultural fields cultivating sweet sorghum was previously identified to produce feruloyl esterases (FAEs). The enzymes responsible for feruloyl esterase activity were purified to homogeneity and named as AtFAE‐1, AtFAE‐2, and AtFAE‐3. The enzymes were monomeric having molecular masses of 74, 23 and 36 kDa, respectively. Active protein bands were identified by a developed pH‐dependent zymogram on native PAGE. The three enzymes exhibited variation in pH tolerance ranging between pH 5–8 and thermostability of up to 55°C. Inhibition studies revealed that the serine residue was essential for feruloyl esterase activity; moreover aspartyl and glutamyl residues are not totally involved at the active site. Metal ions such as Ca2+, K+, and Mg2+ stabilized the enzyme activity for all three FAEs. Kinetic data indicated that all three enzymes showed catalytic efficiencies (kcat/Km) against different synthesized alkyl and aryl esters indicating their broad substrate specificity. The peptide mass fingerprinting by MALDI/TOF‐MS analysis and enzyme affinity toward methoxy and hydroxy substituents on the benzene ring revealed that the AtFAE‐1 belonged to type A while AtFAE‐2 and AtFAE‐3 were type C FAE. The FAEs could release 65 to 90% of ferulic acid from agrowaste substrates in the presence of xylanase. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:924–932, 2013 相似文献
286.
287.
Ibrar Ahmed Peter J. Matthews Patrick J. Biggs Muhammad Naeem Patricia A. McLenachan Peter J. Lockhart 《Molecular ecology resources》2013,13(5):929-937
Recently, we reported the chloroplast genome‐wide association of oligonucleotide repeats, indels and nucleotide substitutions in aroid chloroplast genomes. We hypothesized that the distribution of oligonucleotide repeat sequences in a single representative genome can be used to identify mutational hotspots and loci suitable for population genetic, phylogenetic and phylogeographic studies. Using information on the location of oligonucleotide repeats in the chloroplast genome of taro (Colocasia esculenta), we designed 30 primer pairs to amplify and sequence polymorphic loci. The primers have been tested in a range of intra‐specific to intergeneric comparisons, including ten taro samples (Colocasia esculenta) from diverse geographical locations, four other Colocasia species (C. affinis, C. fallax, C. formosana, C. gigantea) and three other aroid genera (represented by Remusatia vivipara, Alocasia brisbanensis and Amorphophallus konjac). Multiple sequence alignments for the intra‐specific comparison revealed nucleotide substitutions (point mutations) at all 30 loci and microsatellite polymorphisms at 14 loci. The primer pairs reported here reveal levels of genetic variation suitable for high‐resolution phylogeographic and evolutionary studies of taro and other closely related aroids. Our results confirm that information on repeat distribution can be used to identify loci suitable for such studies, and we expect that this approach can be used in other plant groups. 相似文献
288.
Oreenaiza Nordin Wesley Donald Wong Hong Ming Teoh Guat Ney Khairul Asuad Mohamed Nor Azlina Abdul Halim Peter Winskill Azahari Abdul Hadi Zulkamal Safi'in Muhammad Renaud Lacroix Sarah Scaife Andrew Robert McKemey Camilla Beech Murad Shahnaz Luke Alphey Derric David Nimmo Wasi Ahmed Nazni Han Lim Lee 《PloS one》2013,8(3)
Dengue is the most important mosquito-borne viral disease. No specific treatment or vaccine is currently available; traditional vector control methods can rarely achieve adequate control. Recently, the RIDL (Release of Insect carrying Dominant Lethality) approach has been developed, based on the sterile insect technique, in which genetically engineered ‘sterile’ homozygous RIDL male insects are released to mate wild females; the offspring inherit a copy of the RIDL construct and die. A RIDL strain of the dengue mosquito, Aedes aegypti, OX513A, expresses a fluorescent marker gene for identification (DsRed2) and a protein (tTAV) that causes the offspring to die. We examined whether these proteins could adversely affect predators that may feed on the insect. Aedes aegypti is a peri-domestic mosquito that typically breeds in small, rain-water-filled containers and has no specific predators. Toxorhynchites larvae feed on small aquatic organisms and are easily reared in the laboratory where they can be fed exclusively on mosquito larvae. To evaluate the effect of a predator feeding on a diet of RIDL insects, OX513A Ae. aegypti larvae were fed to two different species of Toxorhynchites (Tx. splendens and Tx. amboinensis) and effects on life table parameters of all life stages were compared to being fed on wild type larvae. No significant negative effect was observed on any life table parameter studied; this outcome and the benign nature of the expressed proteins (tTAV and DsRed2) indicate that Ae. aegypti OX513A RIDL strain is unlikely to have any adverse effects on predators in the environment. 相似文献
289.
Mohammad Oves Mohammad Saghir Khan Almas Zaidi Arham S. Ahmed Faheem Ahmed Ejaz Ahmad Asif Sherwani Mohammad Owais Ameer Azam 《PloS one》2013,8(3)
Biofabricated metal nanoparticles are generally biocompatible, inexpensive, and ecofriendly, therefore, are used preferably in industries, medical and material science research. Considering the importance of biofabricated materials, we isolated, characterized and identified a novel bacterial strain OS4 of Stenotrophomonas maltophilia (GenBank: ). At neutral pH, this Gram negative bacterial strain significantly reduced hexavalent chromium, an important heavy metal contaminant found in the tannery effluents and minings. Subsequently, even at room temperature the supernatant of log phase grown culture of strain OS4 also reduced silver nitrate (AgNO3) to generate nanoparticles (AgNPs). These AgNPs were further characterized by UV–visible, Nanophox particle size analyzer, XRD, SEM and FTIR. As evident from the FTIR data, plausibly the protein components of supernatant caused the reduction of AgNO3. The cuboid and homogenous AgNPs showed a characteristic UV-visible peak at 428 nm with average size of ∼93 nm. The XRD spectra exhibited the characteristic Bragg peaks of 111, 200, 220 and 311 facets of the face centred cubic symmetry of nanoparticles suggesting that these nanoparticles were crystalline in nature. From the nanoparticle release kinetics data, the rapid release of AgNPs was correlated with the particle size and increasing surface area of the nanoparticles. A highly significant antimicrobial activity against medically important bacteria by the biofabricated AgNPs was also revealed as decline in growth of Staphylococcus aureus (91%), Escherichia coli (69%) and Serratia marcescens (66%) substantially. Additionally, different cytotoxic assays showed no toxicity of AgNPs to liver function, RBCs, splenocytes and HeLa cells, hence these particles were safe to use. Therefore, this novel bacterial strain OS4 is likely to provide broad spectrum benefits for curing chromium polluted sites, for biofabrication of AgNPs and ultimately in the nanoparticle based drug formulation for the treatment of infectious diseases. JN247637.1相似文献
290.
Respiratory Viruses Associated Hospitalization among Children Aged <5 Years in Bangladesh: 2010-2014
Nusrat Homaira Stephen P. Luby Kamal Hossain Kariul Islam Makhdum Ahmed Mustafizur Rahman Ziaur Rahman Repon C. Paul Mejbah Uddin Bhuiyan W. Abdullah Brooks Badrul Munir Sohel Kajal Chandra Banik Marc-Alain Widdowson Melisa Willby Mahmudur Rahman Joseph Bresee Katharine-Sturm Ramirez Eduardo Azziz-Baumgartner 《PloS one》2016,11(2)