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排序方式: 共有574条查询结果,搜索用时 125 毫秒
1.
The osmotic water outflow of large multilamellar liposomes containing 1-acid glycoprotein was measured at a temperature near the lipid's phase transition temperature. The liposomes were formed from a mixture of DPPC, cholesterol and glycoprotein in molar ratios 100:20:1, by continuous sucrose density gradient centrifugation. These liposomes captured 35% of the radiolabeled glycoprotein. The temperature-dependent experiments showed that near phase transition temperature the initial rate of water outflow increased drastically in comparison with glycoprotein free liposomes incubated in buffer containing glycoprotein. We suggested that eventual a channel mechanism may be involved due to spontaneous incorporation of glycoprotein into the bilayer. 相似文献
2.
Measurements have been made of light-induced conductivity changes and the associated kinetics of the relaxation processes in aqueous suspensions and sonicated liposomes containing bacteriorhodopsin (bR). Aqueous suspensions exhibit a single relaxation time of 1 to 2 ms. The addition of D2O to the aqueous suspension slows down the relaxation time, fourfold. Similar behaviour is seen in sonicated liposomes with a relaxation time of 2 to 3 ms. Activation energies of approximately 14 and 6 kJM-1 are obtained for the effect in sonicated liposomes and aqueous suspension containing bR, respectively. These relaxation processes with lifetime of 1 to 2 ms suggest conformational changes in the protein moiety of bR which most probably may be associated with protonation-deprotonation processes or less likely the release and binding of small ions. 相似文献
3.
Cecilia Zazueta José A. Holguín Jorge Ramírez 《Journal of bioenergetics and biomembranes》1991,23(6):889-902
We describe a calcium transport that is sensitive to ruthenium red in liposomes reconstituted with mitochondrial extracts. This system is able to build an internally negative membrane potential, which allows the electrogenic influx of Ca2+ and Sr2+. Proteins with molecular weights higher than 35 kDa were incorporated to the vesicles, and enhanced the accumulation of the cation in an energy-dependent fashion. 相似文献
4.
V P Torchilin A L Klibanov N N Ivanov M A Gluckhova V E Koteliansky H K Kleinman G R Martin 《Journal of cellular biochemistry》1985,28(1):23-29
We have incorporated antibodies against fibronectin or laminin into liposomes and studied their interaction with insoluble forms of these antigens. The antibodies, after modification by palmitoylchloride, were incorporated into the lipid bilayer by the cholate dialysis method. The antibodies in the liposomes recognized their specific antigen with little reaction to the alternative attachment protein or to albumin (less than 2%). The binding of antibody-containing liposomes to insoluble antigen was inhibited by soluble antibodies to the respective antigens but not by antibodies to other antigens. The affinity constant of the liposome-antibody complex with the antigen was estimated at 1-10 X 10(-9) M liposomes. Thus, antibodies in liposomes retain their reactivity and specificity, and the reaction constant is comparable to that observed for immune complexes. 相似文献
5.
Lanfranco Corazzi Giuseppe Fratto Roberto Pistolesi Giuseppe Arienti 《The Journal of membrane biology》1989,112(2):123-129
Summary Liposomes are prepared from rat brain microsomal lipid and loaded with either Tb3+ or dipicolinic acid (DPA) to test fusion with the Tb-DPA assay. They are also loaded with octadecyl Rhodamine B chloride (R18) to test fusion with the R18 assay. The addition of either Ca2+ or Mg2+ to loaded liposomes develops fluorescence with both assays. The fluorescence elicited by Mg2+ is similar to that elicited by Ca2+ if assessed with R18, but much higher if determined by Tb-DPA. The Ca2+-dependent fluorescence of the Tb-DPA complex is not suppressed by the addition of EDTA, and therefore it is internal to vesicles. The contrary is true for the Mg2+-dependent fluorescence. Rat brain microsomes can be disrupted by adding octylgucoside and reconstituted by removing it by dialysis. We use this procedure to load microsomes with DPA. This allows the use of the Tb-DPA assay for testing the fusion of rat brain microsomes. Reconstituted microsomes fuse with liposomes. This fusion has characteristics similar to those of liposome-liposome fusion. However, no microsome-microsome fusion could be detected with either method. The two methods give different results, owing to the chemical properties of the assays. Indeed Tb-DPA implies the retention of vesicle content, whereas this is not required by the R18 assay. 相似文献
6.
Asim K. Dutta-Roy Margaret J. Gordon Derek J. Leishman Brian J. Paterson Garry G. Duthie William P. T. James 《Molecular and cellular biochemistry》1993,123(1-2):139-144
An -tocopherol-binding protein has been isolated and purified from rabbit heart cytosol. The purified protein had an apparent molecular mass of 14,200, as derived from SDS-PAGE. The content of the protein in rabbit heart was around 11.8 g per g of tissue. The binding of -tocopherol to the purified protein was rapid, reversible, and saturable. Neither nor tocopherol could displace the bound -tocopherol from the protein, suggesting a high specificity for -tocopherol. -Tocopherol-binding protein did not bind oleate. Transfer of -tocopherol from liposomes to mitochodria was stimulated 8-fold in the presence of the binding protein, suggesting that this protein may be involved in the intracellular transport of -tocopherol in the heart. 相似文献
7.
8.
Isabel Haro Rosa M. Pinto Juan F. Gonzalez-Dankaart Jose A. Perez Francisca Reig Albert Bosch 《Microbiology and immunology》1995,39(7):485-490
Peptide VP1 (11-25) of the capsid of hepatitis A virus was synthesized by the Fmoc-polyamide solid phase method, and administered to mice in different forms: (1) free, (2) encapsulated in multilamellar liposomes, (3) coupled to keyhole limpet hemocyanin (KHL), and (4) incorporated into a tetrameric branched lysine core. The highest anti-VP1 peptide responses were generated by synthetic peptides entrapped into liposomes and coupled to KLH. No anti-HAV response was generated with the free peptide, while all the other forms induced both anti-HAV and HAV-neutralizing antibodies. Maximum neutralization indices were observed in ascites from mice treated with liposome-entrapped and KLH peptides. 相似文献
9.
B. Eleazar Cohen 《The Journal of membrane biology》1982,68(1):79-88
Summary An osmotic method was used to study the salt permeability induced by gramicidin A in liposomes. Sequences of cation permeation were obtained for iodide, salycilate, acetate und formate salts in liposomes below and above their transition temperature. Salycilate and formate salts, unlike acetate and iodide salts, exhibit the same sequences for cation selectivity in liposomes below and above their transition temperature. These results can be explained by assuming three mechanisms for salt permeation across gramicidin-containing liposomes: (i) the anion moves by the lipid part of the membrane whereas the cation moves by the gramicidin channel, (ii) movement of the undissociated acid species occurs through the lipid part of the membrane followed by cation-proton exchange via the gramicidin channel and (iii) the cation and anion may move simultaneously via the gramicidin channel.When the movement of the anion or undissociated acid across the lipid part of the membrane is not rate limiting the permeation process, the cation selectivity obtained agrees with the cation selectivity of the gramicidin A channel, as determined by others using independent measurements. 相似文献
10.
Wayne K. Hoffman Peter Lalley Jean Deb Butler Sheldon Orloff Joseph D. Schulman Anil B. Mukherjee 《In vitro cellular & developmental biology. Plant》1981,17(8):735-740
Summary Using lipochromosomes (phospholipid-entrapped chromosomes) we have transferred the human HGPRT gene into HGPRT deficient mouse
cells (A9) with a frequency of approximately 1×10−5 (Mukherjee et al., Proc. Natl. Acad. Sci. USA 75: 1361–1365; 1978). Two other genes located on the long arm of the human
X-chromosome were also expressed in two independently derived populations of transferents (A9/GT3 and A9/GT4). We report here
the chromosomal and enzymatic composition of human HGPRT-positive clones from each subpopulation analyzed in detail with alkaline
Giemsa-11 staining.
All the clones expressed human PGK and HGPRT, but one (A9/GT4C6) lacked human G6PD. In each of four clones examined microscopically,
a small piece of presumptive human chromatin was visible in the karyotypes of most cells. The chromatin fragment was free
or attached in each cell of an individual clone. When integrated, the human chromosomal fragment in each clone appeared associated
with the centromere of the same telocentric A9 chromosome (No. 6 by Q-banding).
These data suggest that: (a) substantial human chromosomal fragments can be transferred into recipient cells using the lipochromosome
technique; (b) clones from human HGPRT positive A9 transferent subpopulations may or may not possess other human X-linked
markers; (c) the stability of lipochromosomally transferred genes varied from clone to clone and stability is generally poor
in the absence of continuous selection pressure (e.g., HAT); (d) when multiple X-linked human genes were transferred to mouse
cells a cytologically detectable human chromosomal fragment was identified free or attached to a host chromosome; and (e)
integration of transferred human chromosomal material into mouse chromosomes may occur at preferential site(s) in the recipient
genome.
This research was sponsored in part by the Office of Health and Environmental Research U.S. Department of Energy under Contract
W-7405-eng-26 with the Union Carbide Corporation. 相似文献