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1.
J. Kelley Bentley Peter W. Reed 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,678(2):238-244
All of the common cytochalasins activate superoxide anion release and exocytosis of β-N-acetylglucosaminidase and lysozyme from guinea-pig polymorphonuclear leukocytes (neutrophils) incubated in a buffered sucrose medium. Half-maximal activation of both processes is produced by approx. 2 μM cytochalasin A, C >μM cytochalasin B ? 4–5 μM cytochalasin D, E. While maximal rates of O2? release and extents of exocytosis require extracellular calcium (1–2 mM), replacing sucrose with monovalent cation chlorides is inhibitory to neutrophil activation by cytochalasins. Na+, K+ or choline inhibited either cytochalasin B- or E-stimulated O2? production with IC50 values of 5–10 mM and inhibition occurs whether Cl?, NO3? or SCN? is the anion added with Na+ or K+. Release of β-N-acetylglucosaminidase in control or cytochalasin B-stimulated cells is inhibited by NaCl (IC50 ≈ 10 mM), while cytochalasin E-stimulated exocytosis is reduced less and K+ or choline chloride are ineffective in inhibiting either cytochalasin B- or E-stimulated exocytosis. Release of β-glucuronidase, myeloperoxidase or acid phosphatase from neutrophils incubated in buffered sucrose is not stimulated by cytochalasin B. Stimulation of either O2? or β-N-acetylglucosaminidase release by low concentrations of cytochalasin A is followed by inhibition of each at higher concentrations. It appears that all cytochalasins can activate both NAD(P)H oxidase and selective degranulation of neutrophils incubated in salt-restricted media and that differential inhibition of these two processes by monovalent cations and/or anions is produced at some step(s) subsequent to cytochalasin interaction with the cell. 相似文献
2.
Biosynthesis of vitamin K (menaquinone) in bacteria. 总被引:17,自引:0,他引:17
3.
4.
Barbara R. Grubb Suzanne M. Driscoll P. J. Bentley 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1987,157(2):181-186
In vitro measurements were made of transmural potential difference (PD), short-circuit current (Isc), resistance and unidirectional fluxes of 22Na and 36Cl across the duodenum, jejunum, ileum and colon of normal sodium-replete domestic fowl (Gallus domesticus). The PD ranged from about 1 mV across the duodenum to 8 mV across the colon while the Isc was, respectively, 2.8 and 64 microA X cm-2. The jejunum and ileum exhibited values between these extremes. Unidirectional fluxes (under short-circuit conditions) of Na and Cl were lowest across the duodenum where there was no evidence of active transport of these ions. Unidirectional fluxes of Na and Cl were less across the jejunum than across the ileum or colon. A net active transport of Na (but not Cl) was observed in the ileum (= 106% of the Isc) and colon (= 50% of Isc). The possible physiological significance of these observations in the domestic fowl are discussed and are compared to that of a mammal, the rabbit. 相似文献
5.
6.
Bone marrow stromal proteoglycan heterogeneity: phenotypic variability between cell lines and the effects of glucocorticoid 总被引:1,自引:0,他引:1
S A Bentley S L Kirby P Anklesaria J S Greenberger 《Journal of cellular physiology》1988,136(1):182-187
Hematopoiesis in vivo is dependent upon the interaction of hematopoietic stem cells with a complex microenvironment, of which stromal proteoglycans are an important functional component. Certain bone marrow stromal cell lines provide a microenvironment that supports hematopoiesis in vitro, a function that is dependent upon glucocorticoid supplementation. Proteoglycan synthesis in the hematopoietic-supportive D2XRII, Bl6 and 14F1 bone marrow stromal cell lines was studied by 35S-sulfate precursor labelling and ion-exchange separation, followed by isopyknic CsCl density centrifugation and gel filtration HPLC. The effects of glucocorticoid were also investigated. A similar pattern of proteoglycan heterogeneity was observed in all three cell lines, although there was considerable quantitative variation. All cultures synthesized three species of chondroitin/dermatan sulfate (CS/DS) proteoglycans: DS1, excluded from a Bio-Sil TSK-400 HPLC column, and DS2, eluting at Kd = 0.31, were present mainly in the culture media. The smallest (DS3) eluted at Kd = 0.63 and was present mainly in the cell layers. CS/DS species were the major proteoglycans in all cultures. Hydrocortisone-free cultures also synthesized heparan sulfate (HS) proteoglycans, including a cell-associated form (HS1), partially excluded from the TSK-400 column, and a secretory form (HS2), eluting at Kd = 0.15. D2XRII cells also secreted an apparently-unique, high-density proteoglycan, Kd = 0.65, into the culture medium. Hydrocortisone at 10(-6) M virtually abolished HS proteoglycan synthesis in all three cell lines, and altered the pattern of CS/DS proteoglycans in the culture media, increasing the quantity of DS1 and DS3, and reducing the quantity of DS2. 相似文献
7.
Localization of the ganglioside-binding site of fibronectin 总被引:10,自引:0,他引:10
L K Thompson P M Horowitz K L Bentley D D Thomas J F Alderete R J Klebe 《The Journal of biological chemistry》1986,261(11):5209-5214
It has been demonstrated via biological assays that fibronectin possesses a receptor for gangliosides that is involved in cell adhesion and restoration of the normal morphology of transformed cells. In this study, fluorescence polarization has been employed to monitor the binding of ganglioside oligosaccharide to fibronectin. Parameters involved in ganglioside oligosaccharide binding to fibronectin are described and compared to the interaction of heparin with fibronectin. A Kd of 1.4 X 10(-8) mol/liter has been calculated, and it is demonstrated that labeled ganglioside oligosaccharides can be eluted from fibronectin with either unlabeled ganglioside oligosaccharides or 4 M urea. Using the fluorescence polarization assay developed in this study for measurement of ganglioside binding to fibronectin, it is demonstrated that gangliosides bind to the 31,000-dalton amino terminal heparin-binding domain of fibronectin. A ganglioside-Sepharose affinity column has been constructed which specifically binds the 31,000-dalton amino terminal fragment of fibronectin. The localization of the ganglioside receptor to the amino terminal domain of fibronectin indicates that the ganglioside receptor is distinct from the putative fibronectin cell surface receptor which is located near the center of the fibronectin molecule. 相似文献
8.
1. The following compounds, added to the growth medium of Fusarium javanicum, were converted into labelled javanicin with the percentage incorporations noted in parentheses: [Me-14C]methionine (0·83); [1-14C]acetate (0·70); [2-14C]malonate (0·07). 2. Labelled samples of javanicin were degraded by Zeisel reaction, Kuhn–Roth oxidation and reaction with sodium hypoiodite; acetic acid obtained from the Kuhn–Roth reaction was further degraded by the Schmidt reaction. Labelled methionine was used only for the formation of the methoxyl group, and the remaining carbon atoms were derived by the acetate-plus-polymalonate pathway. The methyl group attached directly to the naphthaquinone ring is derived by the reduction of a carboxyl group. 3. The demonstration of this biosynthetic pathway supports the assignment of the methoxyl group at position 7. 相似文献
9.
S A Bentley S L Kirby P Anklesaria J S Greenberger 《Journal of cellular physiology》1990,145(1):53-59
The Steel anemia of mice results from an inherited defect in the hematopoietic microenvironment. Proteoglycans synthesized by bone marrow stromal cells are an important functional component of the hematopoietic microenvironment in normal animals. It is thus possible that Steel anemia results from a molecular abnormality involving bone marrow stromal proteoglycans. To investigate this possibility, we studied proteoglycan synthesis in three stromal cell lines from Steel anemic (Sl/Sld) animals and two control stromal cell lines, one (+/+2.4) from a non-anemic littermate, and one (GBl/6) from a normal mouse. Proteoglycans were precursor labelled with 35S sulfate and separated by ion exchange HPLC, CsCl density gradient centrifugation, and molecular sieve HPLC. Glycosaminoglycan (GAG) moieties were characterized by molecular sieve HPLC and enzyme sensitivity. There were no consistent differences in total proteoglycan synthesis, proteoglycan heterogeneity, GAG hydrodynamic size, or enzyme sensitivity among the cell lines studied. Growth factor binding to stromal extracellular matrix (ECM) was studied by co-culture of an IL-3-dependent cell line (FDC-P1) with cell-free ECM preparations from an Sl/Sld and a control (GBl/6) stromal cell line, with and without pre-incubation with IL-3. Cell-free ECM preparations from Sl/Sld and control cell lines supported FDC-P1 growth to an approximately equal extent after pre-incubation with IL-3. FDC-P1 growth support by ECM preparations from both cell lines was also observed without IL-3 pre-incubation, although to a lesser extent, suggesting ECM binding of endogenous growth factors synthesized by the stromal cells. 相似文献
10.
Kathleen D. Murray Eleanor Groden Francis A. Drummond A. Randall Alford Richard H. Storch Michael D. Bentley 《Entomologia Experimentalis et Applicata》1996,80(3):503-510
The effects of citrus limonoids, applied topically to potato (Solanum tuberosum L. var. Katahdin) foliage, on Colorado potato beetle (Leptinotarsa decemlineata) (Say) (Chrysomelidae) larval development, growth, and survival were quantified in laboratory assays and a small-plot field test. In laboratory assays, survival, development rate, and body weight decreased with increasing limonoid concentration, however these measures of larval response did not significantly differ among varying periods of limonoid exposure (three, six, or nine days). Significant limonoid application concentration and frequency effects on survival, development rate, and defoliation were observed in the field test. These results indicate the potential utility of lethal and non-lethal effects of citrus limonoids for management of the Colorado potato beetle. 相似文献