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961.
962.
Florine Cavelier Christine Enjalbal Jérome Santolini Francis Haraux Claude Sigalat Jean Verducci François André 《Letters in Peptide Science》1997,4(4-6):283-288
Tentoxin[cyclo-(MeAla1-Leu2-MePhe3-Gly4] is a metabolite isolated from a phytopathogenic fungusAlternaria alternata, which induces chlorosis of many plants. This potentialnatural herbicide binds specifically to the soluble part CF1of the chloroplastic coupling factor, which is a proton ATP-synthase. Theeffect of the toxin is concentration dependent: at low concentration it is apowerful inhibitor, while at higher concentration, it stimulates the enzyme.We synthesized tentoxin and we designed new analogues in order to vary thehydrophobicity on the side chain and to study the structure activityrelationships. Comparative activities suggest that it is possible toseparate inhibitory and activating effects using tentoxin analogues, showingsome evidence for the existence of two binding sites with different affinityconstant. 相似文献
963.
Petra Düx Brian Whitehead Rolf Boelens Robert Kaptein Geerten W. Vuister 《Journal of biomolecular NMR》1997,10(3):301-306
A modified HNHB experiment is presented that allows thedetermination of J(NH) coupling constants directly from the ratio ofcross-peak to diagonal-peak intensities. The experiment was applied to thephotoactive yellow protein (PYP) and yielded the magnitude of 1173J(NH) coupling constants. In addition, 293J(NH(i–1)) coupling constantscould be measured, providing information about the backbone angle .These data, in conjunction with the magnitudes of the3J(HNH) coupling constantsobtained from the HNHA spectrum, effectively discriminate the twopossibilities for the stereospecific assignment of theH resonances in glycine residues. For all eight glycineresidues in PYP that were not subject to conformational averaging and hadnon-degenerate H resonance frequencies, the J-couplingdata, together with limited NOE data, yielded the stereospecific assignmentof the H resonances for these residues. In addition,reliable and precise , dihedral constraints were also derived forthese residues from the J-coupling data. 相似文献
964.
Summary In this article we review recent work on the physiology of proline and 1-pyrroline-5-carboxylate (P5C) in living organisms and consider recent progress in our understanding of the role of P5C synthetase in collagen metabolism and the regulation of urea cycle in vertebrates. Much of this recent progress has been made possible by advances in our knowledge of the enzymes and genes involved in proline biosynthesis in man. The availability of well characterized P5C synthetase deficiency in man has been an impetus for the cloning of the cDNA encoding for this enzyme from man and facilitated the establishment of the phenotype-genotype relationships in P5C synthetase deficiency in higher vertebrates.Abbreviations GK
-glutamyl kinase
- GPR
-glutamyl phosphate reductase
- P5CR
1-pyrroline-5-carboxylate reductase
- GSA
glutamic--semialdehyde
- P5C
1-pyrroline-5-carboxylate
- P1
Inorganic phosphate
- AMP, ADP, ATP
Adenosine 5-mono-, di-, triphosphate
- NAD+, NADH
nicotinamide adenine dinucleotide, and its reduced form
- NADP+, NADPH
nicotinamide adenine dinucleotide phosphate, and its reduced form; DEAF: diethylaminoethyle
- OAT
ornithine amino transferase; CHO: Chinese hamster ovary
- IGF-1
insulin-like growth factor-1
- P5CDH
pyrroline 5carboxylate dehydrogenase
- IMP
inosine 5-monophosphate 相似文献
965.
Summary Versatile three-step procedures for syntheses of seven racemi-fluoro-a-amino acids are described. Alkylation oftert-butyl N-(diphenylmethylene) glycinate with 1-bromo-2-fluoroalkanes gave N-protected aminoacid esters both in anhydrous medium using lithium-diisopropylamide as base at low temperature or in a two phase system of 50% aqueous sodium hydroxide and methylene chloride with triethylbenzylammonium chloride as the phase transfer catalyst at room temperature. Subsequent two-step deprotection with citric acid and hydrochloric acid gave the title compounds in 13–33% overall yields.Dedicated to Professor Dr.mult., Dr.h.c. Alois Haas on the occasion of his 65th birthday 相似文献
966.
Avram Hershko 《Current opinion in cell biology》1997,9(6):788-799
Selective degradation of cyclins, inhibitors of cyclin-dependent kinases and anaphase inhibitors is responsible for several major cell cycle transitions. The degradation of these cell cycle regulators is controlled by the action of ubiquitin—protein-ligase complexes, which target the regulators for degradation by the 26S proteasome. Recent results indicate that two types of multisubunit ubiquitin ligase complexes, which are connected to the protein kinase regulatory network of the cell cycle in different ways, are responsible for the specific and programmed degradation of many cell cycle regulators. 相似文献
967.
Stephen J Peroutka 《Current opinion in biotechnology》1997,8(6):688-691
The long anticipated ‘genetic revolution’ in neuropsychiatry has yet to have an impact on the practice of clinical medicine. Excitement in the 1980s over major genetic breakthroughs in schizophrenia and manic depression, for example, has been replaced in the late 1990s by the sobering realization that most common neuropsychiatric disorders are multifactorial. Despite considerable effort and resources, no ‘causative’ genetic variation has been identified that plays a definitive major role in any common neuropsychiatric disorder. 相似文献
968.
D'Souza S.E. Altekar W. D'Souza S.F. 《World journal of microbiology & biotechnology》1997,13(5):561-564
Fructose-1,6-bisphosphate (FBP) aldolase (EC 4.1.2.13) of Haloferax mediterranei was immobilized by treating the cell extract in the presence of 10% BSA, with the cross-linking reagent, 0.5% glutaraldehyde for 15min, with the retention of 60% of its original activity. The immobilized preparation exhibited a shift in the temperature optimum from 55°C to 65°C. The enzyme showed enhanced stability towards inactivation by radiation and storage (0–5°C) on immobilization. Immobilization also made the enzyme less halophilic, reducing its denaturation on prolonged storage in a non-salt medium, as well as exhibiting optimal activity at a lower KCl concentration (0.5m) as compared to the soluble enzyme (1–2m). 相似文献
969.
Post-translational modifications are fundamental to processes controlling behaviour, including cellular signaling, growth and transformation. As the molecular basis of protein modifications in normal and disease processes are becoming better defined, so new strategies for designing therapeutic entities to control complex disease processes are emerging. 相似文献
970.
David Cowburn 《Current opinion in structural biology》1997,7(6):835-838
Protein tyrosine binding (PTB) and ‘post synaptic density disc-large zo-1’ (PDZ) domains bind to short peptidic ligands by augmentation of one of the domain's β sheets and other recognition mechanisms. The two domain classes have a superficial resemblance to each other, even though no sequential homology exists. The structural bases of the interactions are well understood for the domains now experimentally determined, and ligand—target pairs can probably be identified in favorable cases by analogy with the known domains. For both PTB and PDZ classes, functional activities are still not fully defined: it is possible that these domain classes, along with pleckstrin homology domains, have multiple roles. 相似文献