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Adenosine and the synthetic adenosine agonists 2-chloroadenosine and N6-(L-2-phenylisopropyl)-adenosine were tested for effects on hormone secretion from the rat isolated perfused pancreas. These nucleosides, at concentrations of 5 μM, markedly potentiated both phases of arginine-induced glucagon release; the two synthetic agonists were more effective than adenosine. In the absence of arginine, each of the nucleosides induced a transient burst of glucagon. In contrast, adenosine and both synthetic agonists inhibited arginine-induced insulin secretion to varying degrees and caused only negligible insulin release when perfused without arginine. The adenosine antagonist 8-(-sulfophenyl)-theophylline prevented the actions of adenosine on hormone release from the pancreas. Our data suggest that adenosine potentiation of arginine-induced glucagon release may be mediated via adenosine receptors on alpha cell membranes; such a mechanism could provide an important endogenous control over glucagon secretion. 相似文献
23.
Irreversible thiophosphorylation and activation of tension in functionally skinned rabbit ileum strips by [35S]ATP gamma S. 总被引:4,自引:0,他引:4
Rabbit ileum strips were functionally skinned by exposure to staphylococcal alpha-toxin. Incubation of the strips in the ATP analog ATP gamma S or [35S]ATP gamma S in the presence of Ca2+ (but not in the absence of Ca2+) resulted in a maximal Ca2+-insensitive activated tension that persisted following removal of Ca2+. Correlated with this tension was 35S-labeling of the 20,000-dalton myosin light chain, LC20, that persisted even after removal of Ca2+. Tension in these strips partially relaxed when exposed to ATP (alpha,beta-methylene). In contrast, alpha-toxin-treated strips exposed to ATP or [gamma-32P]ATP showed Ca2+-sensitive, reversible activated tension and reversible 32P-labeling of the LC20. These results are consistent with a currently proposed model of Ca2+ control of smooth muscle contraction involving a myosin light chain kinase-phosphatase system. 相似文献
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25.
B J Fowlkes C J Herman M Cassidy 《The journal of histochemistry and cytochemistry》1976,24(1):322-331
Seventy cervical cytology specimens have been screened by a xero resolution flow analyzer-sorter using propidium iodide and fluorescein isothiocyanate as fluorochromes for nucleus and cytoplasm, respectively. This system shows a 1% sensitivity for detection of abnormal cells using only crude visual data analysis. Screening of clinical specimens was performed on the instrument with a 5.8% false negative rate and a 11.8% false positive rate by comparison with routine visual cytologic evaluation of the same samples. 相似文献
26.
Effect of Polychlorinated Biphenyl Formulations on the Growth of Estuarine Bacteria 总被引:4,自引:4,他引:0 下载免费PDF全文
Polychlorinated biphenyl formulations inhibited the growth of certain estuarine bacteria. The sensitive strains, although exhibiting some similar physiological characteristics, contained both gram-positive and gram-negative bacteria. 相似文献
27.
Lee A. Borthwick Mathieu Kerbiriou Christopher J. Taylor Giorgio Cozza Ioan Lascu Edith H. Postel Diane Cassidy Pascal Trouvé Anil Mehta Louise Robson Richmond Muimo 《PloS one》2016,11(3)
Cystic fibrosis results from mutations in the cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-dependent protein kinase A (PKA) and ATP-regulated chloride channel. Here, we demonstrate that nucleoside diphosphate kinase B (NDPK-B, NM23-H2) forms a functional complex with CFTR. In airway epithelia forskolin/IBMX significantly increases NDPK-B co-localisation with CFTR whereas PKA inhibitors attenuate complex formation. Furthermore, an NDPK-B derived peptide (but not its NDPK-A equivalent) disrupts the NDPK-B/CFTR complex in vitro (19-mers comprising amino acids 36–54 from NDPK-B or NDPK-A). Overlay (Far-Western) and Surface Plasmon Resonance (SPR) analysis both demonstrate that NDPK-B binds CFTR within its first nucleotide binding domain (NBD1, CFTR amino acids 351–727). Analysis of chloride currents reflective of CFTR or outwardly rectifying chloride channels (ORCC, DIDS-sensitive) showed that the 19-mer NDPK-B peptide (but not its NDPK-A equivalent) reduced both chloride conductances. Additionally, the NDPK-B (but not NDPK-A) peptide also attenuated acetylcholine-induced intestinal short circuit currents. In silico analysis of the NBD1/NDPK-B complex reveals an extended interaction surface between the two proteins. This binding zone is also target of the 19-mer NDPK-B peptide, thus confirming its capability to disrupt NDPK-B/CFTR complex. We propose that NDPK-B forms part of the complex that controls chloride currents in epithelia. 相似文献
28.
Measurement of cellular DNA mass by flow microfluorometry with use of a biological internal standard 总被引:2,自引:0,他引:2
E Tannenbaum M Cassidy O Alabaster C Herman 《The journal of histochemistry and cytochemistry》1978,26(2):145-148
Use of a biological standard (chicken erythrocytes) mixed with experimental cell populations allows control of all variables in flow microfluorometric determination of DNA content. These variables include both staining and instrument procedures. In addition, the use of a biological standard allows determination of cellular DNA mass in unperturbed cell populations. DNA mass measured by FMF technique correlates closely with values reported in the literature that used biochemical techniques. 相似文献
29.
Rufus Turner Tobias Baron Siegfried Wolffram Anne Marie Minihane Aedin Cassidy Gerald Rimbach 《Free radical research》2013,47(2):209-216
Soy isoflavones are thought to have a cardioprotective effect that is partly mediated by an inhibitory influence on the oxidation of low density lipoprotein (LDL). However, the aglycone forms investigated in many previous studies do not circulate in appreciable quantities because they are metabolised in the gut and liver. We investigated effects of various isoflavone metabolites, including for the first time the sulphated conjugates formed in the liver and the mucosa of the small intestine, on copper-induced LDL oxidation. The parent aglycones inhibited oxidation, although only 5% as well as quercetin. Metabolism increased or decreased their effectiveness. Equol inhibited 2.65-fold better than its parent compound daidzein and 8-hydroxydaidzein, not previously assessed, was 12.5-fold better than daidzein. However, monosulphated conjugates of genistein, daidzein and equol were much less effective and disulphates completely ineffective. Since almost all isoflavones circulate as conjugates, these data suggest that despite the increased potency produced by some metabolic changes, isoflavones may not be effective antioxidants in vivo unless they are deconjugated again. 相似文献
30.
A comparison of two novel alcohol dehydrogenase enzymes (ADH1 and ADH2) from the extreme halophile Haloferax volcanii 总被引:1,自引:0,他引:1
Leanne M. Timpson Ann-Kathrin Liliensiek Diya Alsafadi Jennifer Cassidy Michael A. Sharkey Susan Liddell Thorsten Allers Francesca Paradisi 《Applied microbiology and biotechnology》2013,97(1):195-203
Haloarchaeal alcohol dehydrogenases are exciting biocatalysts with potential industrial applications. In this study, two alcohol dehydrogenase enzymes from the extremely halophilic archaeon Haloferax volcanii (HvADH1 and HvADH2) were homologously expressed and subsequently purified by immobilized metal-affinity chromatography. The proteins appeared to copurify with endogenous alcohol dehydrogenases, and a double Δadh2 Δadh1 gene deletion strain was constructed to prevent this occurrence. Purified HvADH1 and HvADH2 were compared in terms of stability and enzymatic activity over a range of pH values, salt concentrations, and temperatures. Both enzymes were haloalkaliphilic and thermoactive for the oxidative reaction and catalyzed the reductive reaction at a slightly acidic pH. While the NAD+-dependent HvADH1 showed a preference for short-chain alcohols and was inherently unstable, HvADH2 exhibited dual cofactor specificity, accepted a broad range of substrates, and, with respect to HvADH1, was remarkably stable. Furthermore, HvADH2 exhibited tolerance to organic solvents. HvADH2 therefore displays much greater potential as an industrially useful biocatalyst than HvADH1. 相似文献