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51.
Three-year-old plants of Parthenium argentatum Gray cv. 11591 grown under natural photoperiod were exposed for 60 d to low night temperature (LNT) of 15 °C (daily from
18:00 to 06:00). Effects of the treatment on net photosynthetic rates (P
N), rubber accumulation, and associated biochemical traits were examined. LNT initially reduced P
N with a parallel decline in the activities of ribulose-1,5-bisphosphate carboxylase, fructose bisphosphatase, and sucrose
phosphate synthase for 20–30 d. Later, LNT enhanced P
N and the activities of photosynthetic enzymes. Associated with high P
N in LNT-treated guayule plants was a two-fold increase in rubber content and rubber transferase activity per unit of protein.
The initial decrease in P
N in LNT-treated guayule was associated with low content of chlorophyll (a+b), large starch accumulation, and higher ratio of glucose-6-phosphate/fructose-6-phosphate. Photosystem 2 activity in isolated
chloroplasts was initially decreased, but increased after 30 d. There was a significant increase in the leaf soluble protein
content in LNT-treated plants. Hence the photosynthetic performance of plants grown at 15 °C night temperature for 50 d was
superior to those grown under natural photoperiod in all parameters studied. The high photosynthetic capacity may contribute
to superior rubber yields under LNT.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
52.
S. Ramachandra Rao Usha Tripathi G. A. Ravishankar 《Biocatalysis and Biotransformation》2002,20(2):137-143
Cell suspension cultures of Capsicum frutescens accumulated digoxin, purpureaglycoside A and other unknown derivatives when digitoxin, a cardiac glycoside, was used as a precursor. The feeding of digitoxin complexed with β-cyclodextrin increased the accumulation of digoxin, purpureaglycoside A and other unknown derivatives. Control cultures (without digitoxin) did not produce any of these metabolites. The growth of cells was affected by both digitoxin as well as digitoxin- β-cyclodextrin. The accumulation of purpureaglycoside A and digoxin reached a maximum of 1241 and 374 μg 100 ml -1 culture on the 6th and 2nd day, respectively, which was 3.9 and 4.5 fold higher than cultures treated with digitoxin alone (sampled on the 13th day). The other unknown derivatives formed in digitoxin- β-cyclodextrin fed cultures were 15 times higher than digitoxin alone fed C. frutescens cultures. The addition of glucose to digitoxin- β-cyclodextrin treated cultures increased the accumulation of purpureaglycoside A which reached a maximum of 3589 μg 100 ml -1 culture after 12 h incubation, which was a 2.9 fold increase over cultures treated with digitoxin- β-cyclodextrin alone. 相似文献
53.
Dipnarayan Saha Vajinder Kumar Shripad Ramachandra Bhat Ramamurthy Srinivasan 《Plant Molecular Biology Reporter》2011,29(2):265-277
Isolation and characterization of promoters are important in understanding gene regulation and genetic engineering of crop
plants. Earlier, a pentatricopeptide repeat protein (PPR) encoding gene (At2g39230), designated as Lateral Organ Junction (LOJ) gene, was identified through T-DNA promoter trapping in Arabidopsis thaliana. The upstream sequence of the LOJ gene conferred on the reporter gene a novel LOJ-specific expression. The present study was aimed at identifying and characterizing
the cis-regulatory motifs responsible for tissue-specific expression in the −673 and +90 bases upstream of the LOJ gene recognized as LOJ promoter. In silico analysis of the LOJ promoter revealed the presence of a few relevant regulatory motifs and a unique feature like AT-rich inverted repeat. Deletion
analysis of the LOJ promoter confirmed the presence of an enhancer-like element in the distal region (−673/−214), which stimulates a minimal
promoter-like sequence in the −424/−214 region in a position and orientation autonomous manner. The −136/+90 region of the
LOJ promoter was efficient in driving reporter gene expression in tissues like developing anthers and seeds of Arabidopsis. A positive regulation for the seed- and anther-specific expression module was contemplated within the 5′ untranslated region
of the LOJ gene. However, this function was repressed in the native context by the lateral organ junction-specific expression. The present
study has led to the identification of a novel lateral organ junction-specific element and an enhancer sequence in Arabidopsis with potential applications in plant genetic engineering. 相似文献
54.
Anwesha Dutta Premalatha Shetty Smitha Bhat Yeshaswini Ramachandra Shrinidhi Hegde 《Journal of biomolecular techniques》2012,23(4):128-135
A solvent system that extracts a maximum number of metabolites belonging to diverse chemical classes from complex biofluids, such as plasma, may offer useful inputs to understand the metabolic and physiological state of an individual. The present study compared seven solvent systems for extraction of metabolites from plasma. The extracts were analyzed by mass spectrometry (MS) and MS/MS (MS2) using a quadrupole time-of-flight liquid chromatography/MS system in positive and negative modes of ionization. Metabolites with molecular mass below 400 were identified using Human Metabolome Database MS2 and MS search interfaces. The acetone/isopropanol (2:1) system yielded promising results in positive ionization mode, as the maximum number of MS and MS2 features was detected in the extract. It was found to be superior in extraction of various classes of metabolites, especially organic acids, nucleosides and nucleoside derivatives, and heterocyclic molecules. Glycerophosphocholines in the mass range of 400–700 were found to be efficiently extracted by the methanol/chloroform/water (8:1:1) system. In negative mode as well, the maximum number of MS2 features was detected in methanol/chloroform/water and acetone/isopropanol extracts. The fingerprints of molecular features obtained in the negative and positive modes differed from each other to a significant extent. 相似文献
55.
Min-Kyoo Shin Edwin Vázquez-Rosa Yeojung Koh Matasha Dhar Kalyani Chaubey Coral J. Cintrón-Pérez Sarah Barker Emiko Miller Kathryn Franke Maria F. Noterman Divya Seth Rachael S. Allen Cara T. Motz Sriganesh Ramachandra Rao Lara A. Skelton Machelle T. Pardue Steven J. Fliesler Chao Wang Andrew A. Pieper 《Cell》2021,184(10):2715-2732.e23
56.
Zhao Y Sun L Muralidhara BK Kumar S White MA Stout CD Halpert JR 《Biochemistry》2007,46(41):11559-11567
The crystal structure of P450 2B4 bound with 1-(4-chlorophenyl)imidazole (1-CPI) has been determined to delineate the structural basis for the observed differences in binding affinity and thermodynamics relative to 4-(4-chlorophenyl)imidazole (4-CPI). Compared with the previously reported 4-CPI complex, there is a shift in the 1-CPI complex of the protein backbone in helices F and I, repositioning the side chains of Phe-206, Phe-297, and Glu-301, and leading to significant reshaping of the active site. Phe-206 and Phe-297 exchange positions, with Phe-206 becoming a ligand-contact residue, while Glu-301, rather than hydrogen bonding to the ligand, flips away from the active site and interacts with His-172. As a result the active site volume expands from 200 A3 in the 4-CPI complex to 280 A3 in the 1-CPI complex. Based on the two structures, it was predicted that a Phe-206-->Ala substitution would alter 1-CPI but not 4-CPI binding. Isothermal titration calorimetry experiments indicated that this substitution had no effect on the thermodynamic signature of 4-CPI binding to 2B4. In contrast, relative to wild-type 1-CPI binding to F206A showed significantly less favorable entropy but more favorable enthalpy. This result is consistent with loss of the aromatic side chain and possible ordering of water molecules, now able to interact with Glu-301 and exposed residues in the I-helix. Hence, thermodynamic measurements support the active site rearrangement observed in the crystal structure of the 1-CPI complex and illustrate the malleability of the active site with the fine-tuning of residue orientations and thermodynamic signatures. 相似文献
57.
58.
Kolluru Viswanatha Chaitanya Girish Kumar Rasineni Attipalli Ramachandra Reddy 《Acta Physiologiae Plantarum》2009,31(3):437-443
Five popularly grown mulberry cultivars (K-2, MR-2, TR-10, BC2-59 and S-13) were subjected to drought stress by withholding
irrigation, to obtain leaf water potentials (Ψw) ranging from −0.75, −1.50 and −2.25 MPa. Accumulation of proline, glycine betaine and abscisic acid (ABA) were quantified
in control and water stressed mulberry leaves. The activities of enzymes involved in proline accumulation including glutamate
dehydrogenase (EC1.4.1.2-4), pyrroline-5-carboxylate synthetase (EC 1.2.1.41), pyrroline-5-carboxylate reductase (EC1.5.1.2),
ornithine transaminase (EC 2.6.1.13) were significantly enhanced in the leaves of all the cultivars with decreasing leaf water
potentials, while the activities of proline dehydrogenase (EC 1.5.1.2) were reduced with progressive increase in water stress.
Accumulation of proline, glycine betaine and abscisic acid was relatively higher in S-13 and BC2-59 compared to K-2, MR-2
and TR-10 under water deficit conditions. Our results demonstrate that S-13 and BC2-59 have superior osmoprotectant mechanisms
under water-limited growth regimes. 相似文献
59.
Lysyl tRNA synthetases facilitate amino acylation and play a crucial role in the essential cellular process of translation. They are grouped into two distinct classes (class I and class II). Class I lysyl tRNA synthetase is considered as a drug target for syphilis caused by Treponema pallidum. Comparative genome analysis shows the absence of its sequence homolog in eukaryotes. The structure of class I lysyl tRNA synthetase from Treponema pallidum is unknown and the difficulties in the in vitro culturing of Treponema makes it non-trivial. We used the structural template of class I lysyl tRNA synthetase from the archaea Pyrococcus horikoshii for modeling the Treponema pallidum lysyl tRNA synthetase structure. Thus, we propose the usefulness of the modeled class I lysyl tRNA synthetase for the design of suitable inhibitors towards the treatment of syphilis. 相似文献
60.