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81.
82.
Xiangbin Xu Jufang Bian Songbai Liu Hongmiao Song Nongnong Shi Yuezhi Tao Huizhong Wang 《Molecular breeding : new strategies in plant improvement》2011,27(3):337-346
The PROMOTION OF CELL SURVIVAL 1 (PCS1) gene, encoding an aspartic protease, has an important role in determining the fate of cells in embryonic development and
reproduction processes in Arabidopsis. To explore the potential function of the PCS1 gene in generating reproductive sterility, we placed the PCS1 gene under the control of an 1,869-bp nucleotide sequence from the 3′ end of the second intron (AG-I) of Arabidopsis AGAMOUS and CaMV 35S (–60) minimal promoter [AG-I-35S (–60)::PCS1], and introduced it into tobacco. RT–PCR results demonstrated that the PCS1 gene driven by AG-I-35S (–60) chimeric promoter was expressed only in anthers and carpels in the reproductive tissues of transgenic tobacco. Compared to
wild-type plants, all AG-I-35S (–60) and AG-I-35S (–60)::PCS1 transgenic lines showed a normal phenotype throughout the vegetative growth phase. However, during the reproductive stage,
most AG-I-35S (–60)::PCS1 transgenic plant anthers displayed delayed dehiscence, failed dehiscence, petalody and hypoplasia, and the pollen grains
had different shapes and sizes with a distorted, shrunken, or collapsed morphology. Moreover, three transgenic lines, PCS1-1,
PCS1-3 and PCS1-4, showed higher sterility than wild-type and AG-I-35S (–60) transgenic plants, respectively. These results showed that the construct of AG-I-35S (–60)::PCS1 was partially effective at preventing seed set and provided a novel sterility strategy. 相似文献
83.
Pei Jian-Ming; Yu Xiao-Chun; Bian Jin-Song; Wong Tak-Ming 《American journal of physiology. Cell physiology》1999,277(3):C492
To study the effects of -opioid receptor stimulation onintracellular Ca2+ concentration([Ca2+]i)homeostasis during extracellular acidosis, we determined the effects of-opioid receptor stimulation on[Ca2+]iresponses during extracellular acidosis in isolated single ratventricular myocytes, by a spectrofluorometric method. U-50488H (10-30 µM), a selective -opioid receptor agonist, dosedependently decreased the electrically induced[Ca2+]itransient, which results from the influx ofCa2+ and the subsequentmobilization of Ca2+ from thesarcoplasmic reticulum (SR). U-50488H (30 µM) also increased theresting[Ca2+]iand inhibited the[Ca2+]itransient induced by caffeine, which mobilizesCa2+ from the SR, indicating thatthe effects of the -opioid receptor agonist involved mobilization ofCa2+ from its intracellular poolinto the cytoplasm. The Ca2+responses to 30 µM U-50488H were abolished by 5 µMnor-binaltorphimine, a selective -opioid receptorantagonist, indicating that the event was mediated by the -opioidreceptor. The effects of the agonist on[Ca2+]iand the electrically induced[Ca2+]itransient were significantly attenuated when the extracellular pH(pHe) was loweredto 6.8, which itself reduced intracellular pH(pHi) and increased[Ca2+]i.The inhibitory effects of U-50488H were restored during extracellular acidosis in the presence of 10 µM ethylisopropyl amiloride, a potentNa+/H+exchange blocker, or 0.2 mM Ni2+,a putativeNa+/Ca2+exchange blocker. The observations indicate that acidosismay antagonize the effects of -opioid receptor stimulation viaNa+/H+andNa+/Ca2+exchanges. When glucose at 50 mM, known to activate theNa+/H+exchange, was added, both the resting[Ca2+]iand pHi increased. Interestingly,the effects of U-50488H on [Ca2+]iand the electrically induced[Ca2+]itransient during superfusion with glucose were significantly attenuated; this mimicked the responses during extracellular acidosis. When a high-Ca2+ (3 mM) solutionwas superfused, the resting[Ca2+]iincreased; the increase was abolished by 0.2 mMNi2+, but thepHi remained unchanged. Like theresponses to superfusion with high-concentration glucose andextracellular acidosis, the responses of the[Ca2+]iand electrically induced[Ca2+]itransients to 30 µM U-50488H were also significantly attenuated. Results from the present study demonstrated for the first time thatextracellular acidosis antagonizes the effects of -opioid receptorstimulation on the mobilization ofCa2+ from SR. Activation of bothNa+/H+andNa+/Ca2+exchanges, leading to an elevation of[Ca2+]i,may be responsible for the antagonistic action of extracellular acidosis against -opioid receptor stimulation. 相似文献
84.
Genistein is an isoflavone and phytoestrogen that is a potent inhibitor of cell proliferation and angiogenesis. This study was designed to investigate the binding of genistein to human serum albumin (HSA) under physiological conditions with drug concentrations in the range of 6.7 × 10−6 to 2.0 × 10−5 mol L−1 and HSA concentration at 1.5 × 10−6 mol L−1. Fluorescence quenching methods in combination with Fourier transform infrared (FT-IR) spectroscopy and circular dichroism (CD) spectroscopy was used to determine the binding mode, the binding constant and the protein structure changes in the presence of genistein in aqueous solution. Changes in the CD spectra and FT-IR spectra were observed upon ligand binding, and the degree of tryptophan fluorescence quenching change did significantly in the complexes. These data have proved the change in protein secondary structure accompanying ligand binding. The change in tryptophan fluorescence intensity was used to determine the binding constants. The thermodynamic parameters, the enthalpy change (ΔH) and the entropy change (ΔS) were calculated to be −22.24 kJ mol−1and 19.60 J mol−1 K−1 according to the van’t Hoff equation, which indicated that hydrophobic and electrostatic interactions play the main role in the binding of genistein to HSA. 相似文献
85.
Kasumov T Martini WZ Reszko AE Bian F Pierce BA David F Roe CR Brunengraber H 《Analytical biochemistry》2002,305(1):90-96
We developed gas chromatography-mass spectrometry assays for the concentration and mass isotopomer distribution of propionyl-CoA, methylmalonyl-CoA, and succinyl-CoA in tissues. The assays involves perchloric acid extraction of the tissue, spiking the extract with [(2)H(5)]propionyl-CoA and [(2)H(4)]succinyl-CoA internal standards, and isolation of short-chain acyl-CoA fraction on an oligonucleotide purification cartridge. Propionyl-CoA is reacted with sarcosine and the formed N-propionylsarcosine is assayed as its pentafluorobenzyl derivative. Methylmalonyl-CoA and succinyl-CoA are hydrolyzed and the corresponding acids assayed as tert-butyl dimethylsilyl derivatives. The assay was applied to a study of [U-(13)C(3)]propionate metabolism in perfused rat livers. While propionyl-CoA is only M3 labeled, succinyl-CoA is M3, M2, and M1 labeled because of isotopic exchanges in the citric acid cycle. Methylmalonyl-CoA is M3 and M2 labeled, reflecting reversal of S-methylmalonyl-CoA mutase. Thus, our assays allow measuring the turnover of the coenzyme A derivatives involved in anaplerosis of the citric acid cycle via precursors of propionyl-CoA, i.e., propionate, odd-chain fatty acids, isoleucine, threonine, and valine. 相似文献
86.
A key commonality of most age-related neurodegenerative diseases is the accumulation of aggregation-prone proteins in the brain. Except for the prionoses, the initiation and propagation of these proteopathies in vivo remains poorly understood. In a previous study, we found that the deposition of the amyloidogenic peptide Abeta can be induced by injection of dilute extracts of Alzheimeric neocortex into the brains of Tg2576 transgenic mice overexpressing the human beta-amyloid precursor protein. The present study was undertaken to assess the pathology after long-term (12 months) incubation, and to clarify the distinctive anatomical distribution of seeded Abeta-immunoreactivity. All mice were injected at 3 months of age; 5 months later, as expected, Abeta deposits were concentrated mostly in the injected hemisphere. After 12 months, abundant, transgene-derived Abeta deposits were present bilaterally in the forebrain, but plaque load was still clearly greater in the extract-injected hemisphere. There was also evidence of tau hyperphosphorylation in axons of the corpus callosum that had been injured by the injection, most prominently in transgenic mice, but also, to a lesser degree, in non-transgenic mice. Five months following injection of AD-extract, an isolated cluster of Abeta-immunoreactive microglia was sometimes evident in the ipsilateral entorhinal cortex; the strong innervation of the hippocampus by entorhinal cortical neurons suggests the possible spread of seeded pathology from the injection site via neuronal transport mechanisms. Finally, using India Ink to map the local dispersion of injectate, we found that Abeta induction is especially potent in places where the injectate is sequestered. The AD-seeding model can illuminate the emergence and spread of cerebral beta-amyloidosis and tau hyperphosphorylation, and thus could enhance our understanding of AD and its pathogenic commonalties with other cerebral proteopathies. 相似文献
87.
Zha-Jun Zhan Hong-Ling Bian Jian-Wei Wang Wei-Guang Shan 《Bioorganic & medicinal chemistry letters》2010,20(5):1532-1534
A series of physostigmine analogues were prepared and evaluated for cholinesterase inhibition activities, including acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Most of them showed potent inhibition activities against AChE, in which compound 17 especially exhibited significantly higher selectivity over BChE than phenserine, a compound currently on clinical trial. Discussion about the relationships between structure and activity of these derivatives was also presented. 相似文献
88.
89.
Fei Bian Shousong Yue Zhenying Peng Xiaowei Zhang Gao Chen Jinhui Yu Ning Xuan Yuping Bi 《PloS one》2015,10(3)
The relationship between salt bridges and stability/enzymatic activity is unclear. We studied this relationship by systematic alanine-scanning mutation analysis using the typical M4 family metalloprotease Pseudomonas aeruginosa elastase (PAE, also known as pseudolysin) as a model. Structural analysis revealed seven salt bridges in the PAE structure. We constructed ten mutants for six salt bridges. Among these mutants, six (Asp189Ala, Arg179Ala, Asp201Ala, Arg205Ala, Arg245Ala and Glu249Ala) were active and four (Asp168Ala, Arg198Ala, Arg253Ala, and Arg279Ala) were inactive. Five mutants were purified, and their catalytic efficiencies (k
cat/K
m), half-lives (t
1/2) and thermal unfolding curves were compared with those of PAE. Mutants Asp189Ala and Arg179Ala both showed decreased thermal stabilities and increased activities, suggesting that the salt bridge Asp189-Arg179 stabilizes the protein at the expense of catalytic efficiency. In contrast, mutants Asp201Ala and Arg205Ala both showed slightly increased thermal stability and slightly decreased activity, suggesting that the salt bridge Asp201-Arg205 destabilizes the protein. Mutant Glu249Ala is related to a C-terminal salt bridge network and showed both decreased thermal stability and decreased activity. Furthermore, Glu249Ala showed a thermal unfolding curve with three discernable states [the native state (N), the partially unfolded state (I) and the unfolded state (U)]. In comparison, there were only two discernable states (N and U) in the thermal unfolding curve of PAE. These results suggest that Glu249 is important for catalytic efficiency, stability and unfolding cooperativity. This study represents a systematic mutational analyses of salt bridges in the model metalloprotease PAE and provides important insights into the structure-function relationship of enzymes. 相似文献
90.
Jun Lv Wei Chen Dianjianyi Sun Shengxu Li Iona Y. Millwood Margaret Smith Yu Guo Zheng Bian Canqing Yu Huiyan Zhou Yunlong Tan Junshi Chen Zhengming Chen Liming Li China Kadoorie Biobank collaborative group 《PloS one》2015,10(4)