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101.
Christina Kennedy Natalie Doetsch Dietmar Meletzus Eduardo Patriarca Mohamad Amar Maurizio Iaccarino 《Plant and Soil》1994,161(1):43-57
A plentiful supply of fixed nitrogen as ammonium (or other compounds such as nitrate or amino acids) inhibits nitrogen fixation in free-living bacteria by preventing nitrogenase synthesis and/or activity. Ammonium and nitrate have variable effects on the ability ofRhizobiaceae (Rhizobium, Bradyrhizobium andAzorhizobium) species to nodulate legume hosts and on nitrogen fixation capacity in bacteroid cells contained in nodules or in plant-free bacterial cultures. In addition to effects on nitrogen fixation, excess ammonium can inhibit activity or expression of other pathways for utilization of nitrogenous compounds such as nitrate (through nitrate and nitrite reductase), or glutamine synthetase (GS) for assimilation of ammonium. This paper describes the roles of two key genesglnB andglnD, whose gene products sense levels of fixed nitrogen and initiate a cascade of reactions in response to nitrogen status. While work onEscherichia coli and other enteric bacteria provides the model system,glnB and, to a lesser extent,glnD have been studied in several nitrogen fixing bacteria. Such reports will be reviewed here. Recent results on the identity and function of theglnB andglnD gene products inAzotobacter vinelandii (a free-living soil diazotroph) and inRhizobium leguminosarum biovarviciae, hereinafter designatedR.l. viciae will be presented. New data suggests thatAzotobacter vinelandii probably contains aglnB-like gene and this organism may have twoglnD-like genes (one of which was recently identified and namednfrX). In addition, evidence for uridylylation of theglnB gene product (the PII protein) ofR. l. viciae in response to fixed nitrogen deficiency is presented. Also, aglnB mutant ofR. l. viciae has been isolated; its characteristics with respect to expression of nitrogen regulated genes is described. 相似文献
102.
Nadia Mastroianni Maurizio De Fusco Massimo Zollo Giulia Arrigo Orsetta Zuffardi Alberto Bettinelli Andrea Ballabio Giorgio Casari 《Genomics》1996,35(3):486
Electrolyte homeostasis is maintained by several ion transport systems. Na–(K)–Cl cotransporters promote the electrically silent movement of chloride across the membrane in absorptive and secretory epithelia. Two kidney-specific Na–(K)–Cl cotransporter isoforms are known, so far, according to their sensitivity to specific inhibitors. We have cloned the human cDNA coding for the renal Na–Cl cotransporter selectively inhibited by the thiazide class of diuretic agents. The predicted protein sequence of 1021 amino acids (112 kDa) shows a structure common to the other members of the Na–(K)–Cl cotransporter family: a central region harboring 12 transmembrane domains and the 2 intracellular hydrophilic amino and carboxyl termini. The ex- pression pattern of the human Na–Cl thiazide-sensitive cotransporter (hTSC, HGMW-approved symbol SLC12A3) confirms the kidney specificity. hTSC has been mapped to human chromosome 16q13 by fluorescencein situhybridization. The cloning and characterization of hTSC now render it possible to study the involvement of this cotransport system in the pathogenesis of tubulopathies such as Gitelman syndrome. 相似文献
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105.
Fiorenza Lagona M. Smid Nadia Papasergio Augusto Ferrari Maurizio Ferrari Laura Cremonesi 《Human genetics》1998,102(6):687-690
Fetal male DNA can be identified in maternal blood by polymerase chain reaction (PCR) amplification of Y-specific sequences.
This technology has not reached a satisfactory accuracy and reproducibility in fetal gender determination because of the very
low concentration of fetal cells. Our purpose was to evaluate the possibility of improving the reliability of this test by
setting up a repeated amplification system. We amplified, by nested PCR of the Y-specific sequence DYS14, 137 DNA samples
extracted from maternal peripheral blood (93 from male-bearing and 44 from female-bearing pregnancies ranging from the 6th
to the 36th gestational week). Each maternal DNA sample was tested doubly, in two different PCR sessions, with a total of
four amplifications. We obtained discordant results in the four amplifications in 82/137 (60%) samples. The best interpretation
of these discordant results was obtained by applying a positivity cutoff of at least two positive amplifications for considering
a DNA sample as belonging to a male-bearing pregnancy. We obtained a sensitivity of 83%, a specificity of 93%, a positive
predictive value of 96% and a negative predictive value of 72% in fetal male gender diagnosis. By applying this quadruple
testing system, we significantly improved PCR accuracy and predictive values compared with single and double testing of the
same samples. We conclude that, for future investigations of fetal DNA retrieved from maternal blood, the application of a
quadruple testing system is better than the single PCR test.
Received: 18 August 1997 / Accepted: 12 January 1998 相似文献
106.
Isabella Panfoli Laura Santucci Maurizio Bruschi Andrea Petretto Daniela Calzia Luca A. Ramenghi 《Expert review of proteomics》2013,10(10):801-808
ABSTRACTIntroduction: Shed by most cells, in response to a myriad of stimuli, extracellular vesicles (EVs) carry proteins, lipids, and various nucleic acids. EVs encompass diverse subpopulations differing for biogenesis and content. Among these, microvesicles (MVs) derived from plasma membrane, are key regulators of physiopathological cellular processes including cancer, inflammation and infection. This review is unique in that it focuses specifically on the MVs as a mediator of information transfer. In fact, few proteomic studies have rigorously distinguished MVs from exosomes.Areas covered: Aim of this review is to discuss the proteomic analyses of the MVs. Many studies have examined mixed populations containing both exosomes and MVs. We discuss MVs’ role in cell-specific interactions. We also show their emerging roles in therapy and diagnosis.Expert commentary: We see MVs as therapeutic tools for potential use in precision medicine. They may also have potential for allowing the identification of new biomarkers. MVs represent an invaluable tool for studying the cell of origin, which they closely represent, but it is critical to build a repository with data from MVs to deepen our understanding of their molecular repertoire and biological functions. 相似文献
107.
108.
Colombo F Tintori C Furlan A Borrelli S Christodoulou MS Dono R Maina F Botta M Amat M Bosch J Passarella D 《Bioorganic & medicinal chemistry letters》2012,22(14):4693-4696
The use of Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition permitted the synthesis of a new compound that is able to inhibit the HGF-induced scattering of MDCK (epithelial cells) and in vitro tumorigenesis of H1437 (non-small-cell lung cancer) and GTL-16 (human gastric carcinoma). In agreement with biochemical and biological results, docking studies within the ATP binding site of Met suggested for the new synthesized compound a binding mode similar to that of the active compound Triflorcas previously reported. 相似文献
109.
G Boumis G Giardina F Angelucci A Bellelli M Brunori D Dimastrogiovanni F Saccoccia AE Miele 《Biochemical and biophysical research communications》2012,425(4):806-811
Plasmodium falciparum is the vector of the most prevalent and deadly form of malaria, and, among the Plasmodium species, it is the one with the highest rate of drug resistance. At the basis of a rational drug design project there is the selection and characterization of suitable target(s). Thioredoxin reductase, the first protection against reactive oxygen species in the erythrocytic phase of the parasite, is essential for its survival. Hence it represents a good target for the design of new anti-malarial active compounds. In this paper we present the first crystal structure of recombinant P. falciparum thioredoxin reductase (PfTrxR) at 2.9 Å and discuss its differences with respect to the human orthologue. The most important one resides in the dimer interface, which offers a good binding site for selective non competitive inhibitors. The striking conservation of this feature among the Plasmodium parasites, but not among other Apicomplexa parasites neither in mammals, boosts its exploitability. 相似文献
110.
Tumbarello M Fiori B Trecarichi EM Posteraro P Losito AR De Luca A Sanguinetti M Fadda G Cauda R Posteraro B 《PloS one》2012,7(3):e33705