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41.
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Christopher W. Schmidt Ashley Remy Rebecca Van Sessen John Willman Kristin Krueger Rachel Scott Patrick Mahoney Jeremy Beach Jaqueline McKinley Ruggero D'Anastasio Laura Chiu Michele Buzon J. Rocco De Gregory Susan Sheridan Jacqueline Eng James Watson Haagen Klaus Pedro Da-Gloria Jeremy Wilson Abigail Stone Paul Sereno Jessica Droke Rose Perash Christopher Stojanowski Nicholas Herrmann 《American journal of physical anthropology》2019,169(2):207-226
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Bingchuan Wei Nicholas Woon Lu Dai Raphael Fish Michelle Tai Winode Handagama Ashley Yin Jia Sun Andrew Maier Dana McDaniel Elvira Kadaub Jessica Yang Miguel Saggu Ann Woys Oxana Pester Danny Lambert Alex Pell Zhiqi Hao Gordon Magill Jack Yim Jefferson Chan Lindsay Yang Frank Macchi Christian Bell Galahad Deperalta Yan Chen 《MABS-AUSTIN》2022,14(1)
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A model of structure and catalysis for ketoreductase domains in modular polyketide synthases 总被引:7,自引:0,他引:7
Reid R Piagentini M Rodriguez E Ashley G Viswanathan N Carney J Santi DV Hutchinson CR McDaniel R 《Biochemistry》2003,42(1):72-79
A putative catalytic triad consisting of tyrosine, serine, and lysine residues was identified in the ketoreductase (KR) domains of modular polyketide synthases (PKSs) based on homology modeling to the short chain dehydrogenase/reductase (SDR) superfamily of enzymes. This was tested by constructing point mutations for each of these three amino acid residues in the KR domain of module 6 of the 6-deoxyerythronolide B synthase (DEBS) and determining the effect on ketoreduction. Experiments conducted in vitro with the truncated DEBS Module 6+TE (M6+TE) enzyme purified from Escherichia coli indicated that any of three mutations, Tyr --> Phe, Ser --> Ala, and Lys --> Glu, abolish KR activity in formation of the triketide lactone product from a diketide substrate. The same mutations were also introduced in module 6 of the full DEBS gene set and expressed in Streptomyces lividans for in vivo analysis. In this case, the Tyr --> Phe mutation appeared to completely eliminate KR6 activity, leading to the 3-keto derivative of 6-deoxyerythronolide B, whereas the other two mutations, Ser --> Ala and Lys --> Glu, result in a mixture of both reduced and unreduced compounds at the C-3 position. The results support a model analogous to SDRs in which the conserved tyrosine serves as a proton donating catalytic residue. In contrast to deletion of the entire KR6 domain of DEBS, which causes a loss in substrate specificity of the adjacent acyltransferase (AT) domain in module 6, these mutations do not affect the AT6 specificity and offer a potentially superior approach to KR inactivation for engineered biosynthesis of novel polyketides. The homology modeling studies also led to identification of amino acid residues predictive of the stereochemical nature of KR domains. Finally, a method is described for the rapid purification of engineered PKS modules that consists of a biotin recognition sequence C-terminal to the thioesterase domain and adsorption of the biotinylated module from crude extracts to immobilized streptavidin. Immobilized M6+TE obtained by this method was over 95% pure and as catalytically effective as M6+TE in solution. 相似文献
47.
Wastewater sludge reduced the heat required to inactivate rotavirus SA-11, and ionic detergents were identified as the sludge components responsible for this effect. A similar result was found previously with reovirus (R. L. Ward and C. S. Ashley, Appl. Environ. Microbiol 36:889-897, 1978). The quantitative effects of individual ionic detergents on rotavirus and reovirus were very different, and rotavirus was found to be extremely sensitive to several of these detergents. However, neither virus was destabilized by nonionic detergents. On the contrary, rotavirus was stabilized by a nonionic detergent against the potent destabilizing effects of the ionic detergent sodium dodecyl sulfate. The destabilizing effects of both cationic and anionic detergents on rotavirus were greatly altered by changes in the pH of the medium. 相似文献
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Vicuna Requesens Deborah Gonzalez Romero Maria Elena Devaiah Shivakumar P. Chang Yeun-Kyung Flory Ashley Streatfield Stephen Ring Rebecca Phillips Cassie Hood Nathan C. Marbaniang Cyrus Dean Howard John A. Hood Elizabeth E. 《Transgenic research》2019,28(5-6):537-547
Transgenic Research - Expression of recombinant proteins in plants is a technology for producing vaccines, pharmaceuticals and industrial enzymes. For the past several years, we have produced... 相似文献
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Aaron G. Carfagnini F. Helen Rodd Kayin B. Jeffers Ashley E. E. Bruce 《Environmental Biology of Fishes》2009,86(3):403-409
Female zebrafish housed in aquaria with spatial complexity (plastic plants) over a 13–16-week period showed reduced levels
of aggressive behavior compared to females in bare tanks. In tanks with plants, there was no relationship between levels of
aggression and fecundity but, in bare tanks, females experiencing the highest levels of aggression showed reduced fecundity.
Our results suggest that it may be beneficial, when maintaining zebrafish at moderate to high densities or working with especially
aggressive strains, to house them in spatially complex conditions. 相似文献
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Jennifer L. Belsky Alyssa J. Ashley Premal A. Bhatt Karen V. Gilbert Heather R. Joyce Chunhua Pan Horacio Pappa Samir Z. Wahab 《AAPS PharmSciTech》2010,11(2):994-1004
The water-insoluble procedures in US Pharmacopeia (USP) General Chapter Residual Solvents <467>, which are based on European Pharmacopoeia procedures, were optimized and modified before their inclusion in the chapter to improve their scope, performance, and ruggedness.
The optimized procedures use a static headspace introduction system with a gas chromatograph equipped with a flame ionization
detector. This article describes some of the key changes made to the USP published procedures, including use of dimethyl sulfoxide
(DMSO) or dimethylformamide (DMF) as the solvent, addition of 5 mL of water and 1 mL of sample (dissolved in DMSO or DMF)
to the headspace vial, use of a 3:1 GC split ratio, and use of new matrix-matched system suitability solutions. These procedures
were verified with two different active pharmaceutical ingredients—hydroxyzine pamoate and prednisone. In the investigation,
the more polar material (hydroxyzine pamoate) showed greater recoveries for the optimized procedures when prepared in DMSO.
The less polar material (prednisone) typically had greater recoveries in DMF for the optimized procedures. During experimentation,
insights into sample preparation, additional types of headspace instrumentation, solvent purity, and other parameters were
also gained. 相似文献