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A secondary structure has been predicted for the C termini of the fibrinogen β and γ chains from an aligned set of homologous protein sequences using a transparent method that extracts conformational information from patters of variation and conservation, parsing strings, and patterns of amphiphilicity. The structure is modeled to form two domains, the first having a core parallel sheet flanked on one side by at least two helices and on the other by an antiparallel amphiphilic sheet, with an additional helix connecting the two sheets. The second domain is built entirely from β strands. © 1997 Wiley-Liss, Inc. 相似文献
23.
Effect of nitrate on the synthesis and decay of nitrate reductase of Neurospora 总被引:11,自引:0,他引:11 下载免费PDF全文
George J. Sorger Maria Teresa Debanne Jacqueline Davies 《The Biochemical journal》1974,140(3):395-403
1. A method was developed to examine the turnover of nitrate reductase by the use of tungstate. 2. Evidence is presented which suggests that the disappearance of nitrate reductase activity from Neurospora mycelia exposed to non-inducing conditions is due to the disappearance of the enzyme protein(s) from the mycelia, and not merely due to the disappearance of its (their) catalytic power. 3. The presence of NO(3) (-) in the culture medium slows down the rate of degradation of nitrate reductase in Neurospora in vivo. 相似文献
24.
Helena Barysz Ji Hun Kim Zhuo Angel Chen Damien F. Hudson Juri Rappsilber Dietlind L. Gerloff William C. Earnshaw 《Open biology》2015,5(2)
SMC proteins are essential components of three protein complexes that are important for chromosome structure and function. The cohesin complex holds replicated sister chromatids together, whereas the condensin complex has an essential role in mitotic chromosome architecture. Both are involved in interphase genome organization. SMC-containing complexes are large (more than 650 kDa for condensin) and contain long anti-parallel coiled-coils. They are thus difficult subjects for conventional crystallographic and electron cryomicroscopic studies. Here, we have used amino acid-selective cross-linking and mass spectrometry combined with structure prediction to develop a full-length molecular draft three-dimensional structure of the SMC2/SMC4 dimeric backbone of chicken condensin. We assembled homology-based molecular models of the globular heads and hinges with the lengthy coiled-coils modelled in fragments, using numerous high-confidence cross-links and accounting for potential irregularities. Our experiments reveal that isolated condensin complexes can exist with their coiled-coil segments closely apposed to one another along their lengths and define the relative spatial alignment of the two anti-parallel coils. The centres of the coiled-coils can also approach one another closely in situ in mitotic chromosomes. In addition to revealing structural information, our cross-linking data suggest that both H2A and H4 may have roles in condensin interactions with chromatin. 相似文献
25.
10 new Turkish taxa are described:Arenaria eliasiana, A. sivasica, A. monscragus, A. angustifolioides; Campanula lycica; Scutellaria orientalis subsp.tortumensis; Stachys choruhensis, S. tundjeliensis; Calamintha caroli-henricana; Aristolochia rechingeriana, the latter two species named in honour ofKarl Heinz Rechinger;Allium vuralii.
Dedicated to Prof. DrKarl Heinz Rechinger on the occasion of his 80th birthday. For part I see Pl. Syst. Evol.154, 111–128. 相似文献
26.
Fractional killing arises from cell‐to‐cell variability in overcoming a caspase activity threshold 下载免费PDF全文
Samuel Bandara Joshua J Sims Hannah Hudson Diana Chai Peter K Sorger 《Molecular systems biology》2015,11(5)
When cells are exposed to death ligands such as TRAIL, a fraction undergoes apoptosis and a fraction survives; if surviving cells are re‐exposed to TRAIL, fractional killing is once again observed. Therapeutic antibodies directed against TRAIL receptors also cause fractional killing, even at saturating concentrations, limiting their effectiveness. Fractional killing arises from cell‐to‐cell fluctuations in protein levels (extrinsic noise), but how this results in a clean bifurcation between life and death remains unclear. In this paper, we identify a threshold in the rate and timing of initiator caspase activation that distinguishes cells that live from those that die; by mapping this threshold, we can predict fractional killing of cells exposed to natural and synthetic agonists alone or in combination with sensitizing drugs such as bortezomib. A phenomenological model of the threshold also quantifies the contributions of two resistance genes (c‐FLIP and Bcl‐2), providing new insight into the control of cell fate by opposing pro‐death and pro‐survival proteins and suggesting new criteria for evaluating the efficacy of therapeutic TRAIL receptor agonists. 相似文献
27.
Background
Kinetochores are large multi-protein structures that assemble on centromeric DNA (CEN DNA) and mediate the binding of chromosomes to microtubules. Comprising 125 base-pairs of CEN DNA and 70 or more protein components, Saccharomyces cerevisiae kinetochores are among the best understood. In contrast, most fungal, plant and animal cells assemble kinetochores on CENs that are longer and more complex, raising the question of whether kinetochore architecture has been conserved through evolution, despite considerable divergence in CEN sequence. 相似文献28.
Scheunemann M Sorger D Wenzel B Heinitz K Schliebs R Klingner M Sabri O Steinbach J 《Bioorganic & medicinal chemistry》2004,12(6):1459-1465
Detection of the central cholinergic deficits, a consistent feature of Alzheimer's disease, is essential to allow preventive measures and/or symptomatic treatment already at a very early stage of the disease. The vesicular acetylcholine transporter (VAChT) represents an appropriate target to establish PET radiotracer that are adequate for brain imaging the loss of cholinergic terminals. Here we describe the synthesis and binding characteristics of novel derivatives of vesamicol, known to represent a specific antagonist of VAChT sites. Novel benzyl ether derivatives of vesamicol either 4- or 5-substituted at the cyclohexylring have been synthesized by different regioselective ring opening reactions of a same epoxide precursor. The affinity and selectivity of the novel compounds to VAChT sites were analyzed by competitive radioligand binding studies in rat brain and liver membrane preparations using tritium labeled radioligands. The 4-substituted fluorobenzylether of vesamicol 10b was shown to exhibit a high affinity to VAChT sites (K(i)-value(10b)=10.7+/-1.7 nM), but demonstrated also binding capacities to sigma receptors (K(i-)value(10b)=18.5+/-6.9 nM, [(3)H]DTG; K(i)-value(10b)=30.6+/-9.6 nM, [(3)H]haloperidol). The data suggest the potential of vesamicol derivatives to design appropriate radiotracer for PET imaging of central cholinergic deficits. 相似文献
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Constantin Rüder Tobias Haase Annalena Krost Nicole Langwieser Jan Peter Stefanie Kamann Dietlind Zohlnh?fer 《PloS one》2014,9(8)