全文获取类型
收费全文 | 2528篇 |
免费 | 86篇 |
国内免费 | 74篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 19篇 |
2020年 | 27篇 |
2019年 | 42篇 |
2018年 | 42篇 |
2017年 | 30篇 |
2016年 | 40篇 |
2015年 | 52篇 |
2014年 | 77篇 |
2013年 | 138篇 |
2012年 | 71篇 |
2011年 | 90篇 |
2010年 | 87篇 |
2009年 | 109篇 |
2008年 | 109篇 |
2007年 | 99篇 |
2006年 | 102篇 |
2005年 | 95篇 |
2004年 | 85篇 |
2003年 | 81篇 |
2002年 | 65篇 |
2001年 | 53篇 |
2000年 | 57篇 |
1999年 | 50篇 |
1998年 | 48篇 |
1997年 | 45篇 |
1996年 | 45篇 |
1995年 | 48篇 |
1994年 | 49篇 |
1993年 | 53篇 |
1992年 | 59篇 |
1991年 | 53篇 |
1990年 | 50篇 |
1989年 | 60篇 |
1988年 | 45篇 |
1987年 | 45篇 |
1986年 | 45篇 |
1985年 | 57篇 |
1984年 | 57篇 |
1983年 | 41篇 |
1982年 | 61篇 |
1981年 | 43篇 |
1980年 | 33篇 |
1979年 | 30篇 |
1978年 | 25篇 |
1977年 | 18篇 |
1976年 | 19篇 |
1974年 | 4篇 |
1971年 | 5篇 |
排序方式: 共有2688条查询结果,搜索用时 14 毫秒
1.
PETER BOGNER DENYS N. WHEATLEY CSABA BORBLY ATTILA MISETA 《Cell biology international》1996,20(11):741-749
Exchange of erythrocyte intracellular (i/c) K+for extracellular (e/c) Na+in human erythrocytes treated with sub-CMC concentrations of the non-ionic detergent Brij 58 can be stopped by reincubation in serum or albumin containing solutions. The progressive equilibration of the K+contents of detergent-treated human erythrocytes with the incubation medium was reversed by an albumin-mediated withdrawal of detergent molecules from the cell. Re-establishment of near normal [K+] in terms of K+/kg water proceeds in two ways: (i) a metabolism-dependent net accumulation of K+ions; and (ii) a metabolism-independent shrinkage of erythrocytes, this being the more significant factor. 相似文献
2.
Phosphorylation of Synaptic Membrane Glycoproteins: The Effects of Ca2+ and Calmodulin 总被引:1,自引:0,他引:1
Synaptic membranes were incubated with [gamma-32P]ATP, and glycoproteins were isolated by affinity chromatography on concanavalin A agarose. Glycoproteins accounted for 1.5-2.5% of the total 32P incorporated into synaptic membrane proteins. Ca2+ and calmodulin enhanced the phosphorylation of synaptic membrane glycoproteins approximately threefold. In the presence of Ca2+ and calmodulin, the rate of glycoprotein dephosphorylation was also increased three- to four-fold. Gel electrophoretic analysis identified several synaptic membrane glycoproteins that incorporated 32P, with the most highly labeled glycoprotein under basal phosphorylating conditions having an apparent Mr of 205,000 (gpiii). Ca2+ and calmodulin produced a marked increase in the phosphorylation of a glycoprotein with an apparent Mr of 180,000 (gpiv) and lesser increases in the labeling of three other glycoproteins. Membranes that had been labeled with [gamma-32P]ATP were extracted with Triton X-100 under conditions that yield a detergent-insoluble residue enriched in postsynaptic structures. The Triton X-100 insoluble residue accounted for 20-25% of the 32P associated with synaptic membrane glycoproteins. Gpiv and other glycoproteins, the phosphorylation of which was stimulated by calmodulin, were located exclusively in the Triton X-100 insoluble residue, whereas gpiii and other calmodulin-insensitive glycoproteins partitioned predominantly into the Triton X-100-soluble fraction. Phosphopeptide maps and phosphoamino acid analysis of gpiv isolated from synaptic membranes and a postsynaptic glycoprotein of apparent Mr of 180,000 (gp180) isolated from synaptic junctions indicated that the former protein was identical to the previously identified postsynaptic-specific gp180. In addition to phosphoserine and phosphothreonine, gpiv also contained phosphotyrosine, identifying it as a substrate for tyrosine-protein kinase as well as for Ca2+/calmodulin-dependent protein kinase. 相似文献
3.
There is a sudden increase in free radical levels, measured from the electron spin resonance (ESR) signal, in cut carnation ( Dianthus caryophyllus L. cv. Ember) petal powders between the end of blooming and the onset of withering. There is also an increase in the microsomal generation of superoxide radicals (measured from the ESR-Tiron signal). These increases correspond to a decrease of polar lipids content, a slight increase in peroxides and to the onset of a sudden efflux of electrolytes. A correlation is established between free radical production and the loss of membrane integrity. Catalase (EC 1.11.1.6) activity increases progressively until complete withering and an hypothesis concerning the action of this enzyme is proposed. The changes in superoxide dismutase (EC 1.15.1.1) activity appear to be independent of the amplitude of the ESR-Tiron signal. 相似文献
4.
5.
The higher harmonics of the current caused by an alternating voltage applied to bilayer lipid membranes made of diphytanoyl phosphatidylcholine (DPhPC) in decane and tetradecane were measured. A universal relation between the amplitudes of harmonics was proposed and experimentally verified. This allowed the coefficients of expansion of the capacitance in even powers of voltage to be calculated for the DPhPC membrane in tetradecane; it also permitted comparison of the inhomogeneity in the thickness of the DPhPC membranes in decane and tetradecane. 相似文献
6.
Glycosaminoglycans were isolated from plasma membranes of hepatic and renal tubule cells of guinea pig. Plasmalemma of renal tubule cells contained more total glycosaminoglycans, hyaluronic acid, chondroitin-4 sulfates and chondroitin-6 sulfates, and less dermatan sulfates and heparin sulfates than liver plasma membranes. These glycocalyx components, owing to their polyanionic properties, may have a role in the transport of water, ions, and macromolecules across the cell membrane. 相似文献
7.
Thomas D. Noland Linda J. Van Eldik David L. Garbers Wilson H. Burgess 《Molecular reproduction and development》1985,11(3):297-303
Reproducible concentrations of calmodulin representing approximately 0.1% of the membrane protein were detected in purified plasma membranes from bovine epididymal spermatozoa. When membranes were isolated in the presence of 1 mM EGTA, the amount of calmodulin associated with the plasma membranes was not reduced. Calmodulin-binding proteins were detected in both purified plasma membranes and in a mixed membrane fraction containing both plasma membranes and cytoplasmic droplet membranes. A calcium-dependent, calmodulin-binding protein of apparent molecular weight 123,000 was detected in both fractions. In the presence of 1 mM EDTA, putative calcium-independent calmodulin-binding proteins of apparent molecular weights 93,000, 32,000, 18,000, and 15,000 were detected in the plasma membrane fraction. The 15,000 Mr polypeptide was also present in the mixed membrane fraction but the three proteins of higher molecular weight were reduced or absent in this fraction. 相似文献
8.
Monte Carlo simulations of flexible two-dimensional model membranes embedded in three space dimensions are reported. We explain in detail the techniques how to simulate fluid open membranes and fluid closed membranes (vesicles). It is shown that polymerized open membranes are rough and flat. Accordingly, the two larger components of the inertia tensor are proportional to the number of monomers of the surface, λ3 ≈ λ2 ~ N, whereas the smallest λ1 ~ N 0.65. Polymerized vesicles are isotropic and their mean square radius of gyration is R 2 ~ λ k ~ N. In contrast, fluid membranes and vesicles exhibit crumpled shapes with λ k ~ N 0.8 for k = 1,2,3. A monomer on a fluid surface exhibits a time-dependent mean squared displacement of r 2 (t) ~ t 0.8. 相似文献
9.
Jacqueline Knobloch Daniel K. Suhendro Julius L. Zieleniecki Joseph G. Shapter Ingo K?per 《Saudi Journal of Biological Sciences》2015,22(6):714-718
The direct interaction of drugs with the cell membrane is often neglected when drug effects are studied. Systematic investigations are hindered by the complexity of the natural membrane and model membrane systems can offer a useful alternative. Here some examples are reviewed of how model membrane architectures including vesicles, Langmuir monolayers and solid supported membranes can be used to investigate the effects of drug molecules on the membrane structure, and how these interactions can translate into effects on embedded membrane proteins. 相似文献
10.
Though it is well accepted that adipose tissue is central in the regulation of glycemic homeostasis, the molecular mechanisms governing adipocyte glucose uptake remain unclear. Recent studies demonstrate that mitochondrial dynamics (fission and fusion) regulate lipid accumulation and differentiation in adipocytes. However, the role of mitochondrial dynamics in glucose homeostasis has not been explored. The nitric oxide oxidation products nitrite and nitrate are endogenous signaling molecules and dietary constituents that have recently been shown to modulate glucose metabolism, prevent weight gain, and reverse the development of metabolic syndrome in mice. Although the mechanism of this protection is unclear, the mitochondrion is a known subcellular target for nitrite signaling. Thus, we hypothesize that nitrite modulates mitochondrial dynamics and function to regulate glucose uptake in adipocytes. Herein, we demonstrate that nitrite significantly increases glucose uptake in differentiated murine adipocytes through a mechanism dependent on mitochondrial fusion. Specifically, nitrite promotes mitochondrial fusion by increasing the profusion protein mitofusin 1 while concomitantly activating protein kinase A (PKA), which phosphorylates and inhibits the profission protein dynamin-related protein 1 (Drp1). Functionally, this signaling augments cellular respiration, fatty acid oxidation, mitochondrial oxidant production, and glucose uptake. Importantly, inhibition of PKA or Drp1 significantly attenuates nitrite-induced mitochondrial respiration and glucose uptake. These findings demonstrate that mitochondria play an essential metabolic role in adipocytes, show a novel role for both nitrite and mitochondrial fusion in regulating adipocyte glucose homeostasis, and have implications for the potential therapeutic use of nitrite and mitochondrial modulators in glycemic regulation. 相似文献