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91.
El-Haroun H Clarke DL Deacon K Bradbury D Clayton A Sutcliffe A Knox AJ 《American journal of physiology. Lung cellular and molecular physiology》2008,294(3):L553-L562
We have previously shown that interleukin (IL)-1beta, transforming growth factor (TGF)-beta1, or bradykinin (BK) impair cAMP generation in response to prostacyclin analogs in human pulmonary artery smooth muscle (PASM), suggesting that inflammation can impair the effects of prostacyclin analogs on PASM in pulmonary hypertension. Here we explored the biochemical mechanisms involved. We found that IL-1beta, BK, and TGF-beta1 reduced adenylyl cyclase isoform 1, 2, and 4 mRNA, increased Galphai protein levels, and reduced prostacyclin receptor (IP receptor) mRNA expression. In contrast, Galphas protein levels were unchanged. Protein kinase A (PKA) (H-89, KT-2750, PKIm) and p38 mitogen-activated protein (MAP) kinase (SB-202190) inhibitors attenuated these effects, but protein kinase C (bisindolylmaleide) or phosphoinositol 3-kinase (LY-294002) inhibitors did not. Fluorescent kemptide assay and Western blotting confirmed that PKA and p38 MAP kinase were activated by IL-1beta, BK, and TGF-beta1. These studies suggest that IL-1beta, BK, and TGF-beta1 impair IP receptor-mediated cAMP accumulation by multiple effects on different components of the signaling pathway and that these effects are PKA and p38 MAP kinase dependent. 相似文献
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Chromatosome positioning on assembled long chromatin. Linker histones affect nucleosome placement on 5 S rDNA 总被引:16,自引:0,他引:16
Long chromatin containing linker histones H1 or H5 was assembled on tandemly repeated 172 or 207 base-pair nucleosome positioning sequences from a sea urchin 5 S RNA gene. The effects of H1 and H5 on spacing and positioning of nucleosomes were assessed. In the absence of linker histones, precise determinations of core particle boundaries showed that, although a large proportion of the histone octamers occupy a unique position, there is a small group of other, less populated sites located around this major site. The dominant position was found 10 to 15 base-pairs upstream from the unique position previously reported for the histone octamer on the monomer 260 base-pair sequence. Linker histones do not override the underlying DNA signals that induce the very regular spacing of nucleosomes in chromatins assembled on these strongly positioning multimer DNA sequences. They were nevertheless found to be decisive in determining the chromatosome positions and their distributions, and as such define the chromatosome as a positioning entity. 相似文献
95.
An analysis of the photo-induced decline in the in vivo chlorophyll a fluorescence emission (Kautsky phenomenon) from the bean leaf is presented. The redox state of PS II electron acceptors and the fluorescence emission from PS I and PS II were monitored during quenching of fluorescence from the maximum level at P to the steady state level at T. Simultaneous measurement of the kinetics of fluorescence emission associated with PS I and PS II indicated that the ratio of PS I/PS II emission changed in an antiparallel fashion to PS II emission throughout the induction curve. Estimation of the redox state of PS II electron acceptors at given points during P to T quenching was made by exposing the leaf to additional excitation irradiation and determining the amount of variable PS II fluorescence generated. An inverse relationship was found between the proportion of PS II electron acceptors in the oxidised state and PS II fluorescence emission. The interrelationships between the redox state of PS II electron acceptors and fluorescence emission from PS I and PS II remained similar when the shape of the induction curve from P to T was modified by increasing the excitation photon flux density. The contributions of photochemical and non-photochemical quenching to the in vivo fluorescence decline from P to T are discussed. 相似文献
96.
J. W. Breneman P. M. Yau R. R. Swiger R. Teplitz H. A. Smith J. D. Tucker E. M. Bradbury 《Chromosoma》1996,105(1):41-49
The expression of genes in mammalian cells depends on many factors including position in the cell cycle, stage of differentiation,
age, and environmental influences. As different groups of genes are expressed, their packaging within chromatin changes and
may be detected at the chromsomal level. The organization of DNA within a chromosome is determined to a large extent by the
positively charged, highly conserved histones. Histone subtypes and the reversible chemical modifications of histones have
been associated with gene activity. Active or potentially active genes have been associated with hyperacetylated histones
and inactive genes with nonacetylated histones. Sodium butyrate increases the acetylation levels of histones in cell cultures
and acts as both an inducer of gene activity and as a cell-cycle block. We describe a method to label the interphase distribution
of DNA associated with various histone acetylation stages on chromosomes. Nucleosomes from untreated and butyrate-treated
HeLa cells were fractionated by their acetylation level and the associated DNA labeled, and hybridized to normal human chromosomes.
In the sodium butyrate-treated cells the resulting banding patterns of the high- and low-acetylated fractions were strikingly
different. DNA from low-acetylated chromatin labeled several pericentric regions, whereas hybridization with DNA from highly
acetylated chromatin resulted in a pattern similar to inverse G-bands on many chromsomes. The results from noninduced cells
at both high and low acetylation levels were noticeably different from their induced counterparts. The capture and hybridization
of DNA from interphase chromatin at different acetylation states provides a “snap-shot” of the distribution of gene activity
on chromosomes at the time of cell harvest.
Edited by: P.B. Moens 相似文献
97.
E M Bradbury P D Cary G E Chapman C Crane-Robinson S E Danby H W Rattle M Boublik J Palau F J Aviles 《European journal of biochemistry》1975,52(3):605-613
Proton magnetic resonance, circular dichroism and other studies of whole and cleaved calf thymus histone H1 (formerly F1) reveal the presence of specific folded structures in the region approximately from residue 40--115. Ionic, hydrogen-bond and hydrophobic interactions all appear to contribute to the stability of the structure, which is predicted to contain alpha-helices in regions 42--55 and 58--75. No evidence was found for beta-structures, either inter or intramolecular, or for any structure formation outside the region 40--115. At 18 degrees C and a protein concentration of 2 mM the first-order exchange rate between random-coil and structured forms is slower than 80 s-1; at 40 degrees C the exchange rate is faster than 330 s-1. 相似文献
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