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1.
《Bioorganic & medicinal chemistry》2020,28(8):115432
In the search of new DNA groove binding agents a series of substituted 9,10-methylpyridiniumanthracenes have been synthesized and their interactions with DNA have been studied by UV/vis absorption, CD and fluorescence spectroscopy. A minor groove binding mode is confirmed by DNA melting studies, strong CD effects, the dependence of the binding affinity on ionic strength, and the differentiation between AT and GC base pairs. No binding occurs to GC sequences. Binding constants to calf thymus DNA (ct-DNA) and poly(dA:dT) in the range between 1 × 104 and 3 × 105 M−1 have been determined. The binding strength decreases with the size of substituents attached at the anthracene site. Variation of the substitution pattern of the charged groups shows that methyl groups in meta position cause slightly stronger binding than methyl groups in para position. In contrast, with these groups in ortho position, no binding interaction has been observed. The strongest binding is achieved with an expansion of the peripheral heterocycle from pyridine to quinoline. Molecular modeling reveals the pivotal role of the substitution pattern: Anthracenes with para and meta pyridines align along the minor grooves. On the other hand, the ortho derivative adopts no groove-alignment. 相似文献
2.
《Bioorganic & medicinal chemistry letters》2020,30(17):127397
Herein, a boronic acid-based sensor was reported selectively to recognize Pd2+ ion. The fluorescence intensity increased 36-fold after sensor binding with 2.47 × 10−5 M of Pd2+ ion. It was carried out in the 99% aqueous solution for binding tests, indicating sensor having good water solubility. In addition, it is discernible that Pd2+ ion turned on the blue fluorescence of sensor under a UV–lamp (365 nm), while other ions (Ag+, Al3+, Ba2+, Ca2+, Cr2+, Cd2+, Co2+, Cs2+, Cu2+, Fe2+, Fe3+, K+, Li+, Mg2+, Mn2+, Na+, Ni2+ and Zn2+) did not show the similar change. Furthermore, sensor has a low limit of detection (38 nM) and high selectivity, which exhibits the potential for the development of Pd2+ recognition in practical environments. 相似文献
3.
Fluorescent biosensors are powerful tools for the detection of biochemical events inside cells with high spatiotemporal resolution. Biosensors based on fluorescent proteins often suffer from issues with photostability and brightness. On the other hand, hybrid, chemical–genetic systems present unique opportunities to combine the strengths of synthetic, organic chemistry with biological macromolecules to generate exquisitely tailored semisynthetic sensors. 相似文献
4.
The fluorescent probe erythrosine 5′-iodoacetamide (ER) binds to mitochondrial NADH-CoQ reductase (Complex-I) accompanied by an enhancement of the fluorescence intensity. The binding of the CoQ analogue, 2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinone (DB), decreased the fluorescence intensity of the ER:Complex-I system. The ‘site 1’ inhibitor rotenone did not decrease the fluorescence intensity showing the non-identical nature of the binding sites of DB and rotenone. Also, the reduced form of DB did not decrease the fluorescence intensity. The decrease of the fluorescence intensity by DB was shown to be due to the removal of bound ER by DB. The rapid kinetics of ER binding was studied by temperature-jump relaxation. While DB caused complete elimination of the relaxation process in the ER:Complex-I system, rotenone caused only a decrease in the relaxation rate, suggesting conformational change. The relaxation rate showed a pH dependence with a maximum around pH 7.5. 相似文献
5.
6.
Visualization of the microbody division inCyanidioschyzon merolae with the fluorochrome brilliant sulfoflavin 总被引:1,自引:0,他引:1
M. Miyagishima R. Itoh K. Toda H. Takahashi H. Kuroiwa T. Kuroiwa 《Protoplasma》1998,201(1-2):115-119
Summary A novel procedure is described for fluorescence staining of microbodies, which can be applied quickly and easily. We developed this technique of microbody staining with the unicellular red algaCyanidioschyzon merolae. Cyanidioschyzon merolae only contains a single chloroplast, mitochondrion, and microbody per cell, and the mitotic cycle and the organelle division cycle are easily synchronized. Knowing that the concentration of H2O2 in the microbody is higher than it is in the cytosol and other cell components, we attempted to visualize the microbody by using fluorescence microscopy to detect H2O2. Brilliant sulfoflavin (BSF), used for detecting Fe2+ in analytical chemistry, fluoresces when it reacts with Fe2+ and H2C2. We were able to specifically stain microbodies with BSF, under acidic conditions (pH 3.0 or pH 2.5) with blue-light excitation. Using this procedure, we observed division of the microbody and the effect of aphidicolin on the microbody. We also discovered that microbody division is regulated by the cell nucleus and follows division of the cell nucleus. 相似文献
7.
Salvatore Chiantia Grzegorz Chwastek Zaiguo Li Petra Schwille 《生物化学与生物物理学报:生物膜》2008,1778(5):1356-1364
Ceramide-induced alterations in the lateral organization of membrane proteins can be involved in several biological contexts, ranging from apoptosis to viral infections. In order to investigate such alterations in a simple model, we used a combined approach of atomic force microscopy, scanning fluorescence correlation spectroscopy and confocal fluorescence imaging to study the partitioning of different membrane components in sphingomyelin/dioleoyl-phosphatidylcholine/cholesterol/ceramide supported bilayers. Such model membranes exhibit coexistence of liquid-disordered, liquid-ordered (raft-like) and ceramide-rich lipid phases. Our results show that components with poor affinity toward the liquid-ordered phase, such as several fluorescent lipid analogues or the synaptic protein Synaptobrevin 2, are excluded from ceramide-rich domains. Conversely, we show for the first time that the raft-associated protein placental alkaline phosphatase (GPI-PLAP) and the ganglioside GM1 are enriched in such domains, while exhibiting a strong decrease in lateral diffusion. Analogue modulation of the local concentration and dynamics of membrane proteins/receptors by ceramide can be of crucial importance for the biological functions of cell membranes. 相似文献
8.
In this work we describe not previously explored binding studies on the reversible interaction of benzoxaborole with ligands of medical and pharmaceutical interest such as nucleosidic drugs gemcitabine and capecitabine, as well as the hydrophobic chemotherapeutic doxorubicin. We include functional derivatives of benzoxaborole such as a near infrared fluorescent boronolectine, Cy-Bx, The dynamic covalent interaction in physiological conditions was assessed by spectroscopic techniques yielding moderate to high binding affinities. The cytotoxic activity of the drugs upon conjugation to the boronolectins was evaluated revealing significant influence of the bioconjugation status on the cellular viability. The availability of the conjugate for cellular uptake and localization in the model cancer cell line HeLa was assessed by fluorescence imaging. Benzoxaborole and the fluorescent boronolectin Cy-Bx, proved to be versatile conjugation tools for 1,2 and 1,3-diol containing pharmacophores as well as bioisosteric forms such as 1,2-hydroxyamino, envisioning these small boronolectins as components in systems for drug release with tracking capability. 相似文献
9.
激光光漂恢复技术测定了异硫氰基荧光素标记的林蛀卵表面分子在第一次卵裂前的运动。发现固着在玻片上的剥离“细胞膜”的分子运动形式为扩散。扩散系数为(4.6±1.3)×10~(-12)cm~2/s,可动部份为15%。完整卵子上的分子运动形式为流动。细胞膜在不停地流动着。它可能起着协助细胞质运动的作用。细胞膜流动的速度随时间而异,卵裂前不久,在大多数的卵子上,出现两个流动较慢的谷,少数细胞只测到一个谷。这可能与光漂起始时间,光斑与未来分裂沟的距离,和卵子间的差异有关。也讨论了这种速度变化与表面收缩波的关系。 相似文献
10.
Influence of ionic strength and pH on the interaction between high-affinity heparin and antithrombin
Birgitta Nordenman Ingemar Björk 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,672(3):227-238
Binding constants for the binding of high-affinity heparin to antithrombin at different ionic strengths were determined by fluorescence titrations and were also estimated from dissociation curves of the heparin-antithrombin complex. These curves were monitored by near-ultraviolet circular dichroism or fluorescence. The dependence of the binding constant on the activity of NaCl suggested that maximally 5–6 charged groups are directly involved in the interaction between the two macromolecules. Major pH-dependent changes of the interaction, as evident by changes of the spectroscopic properties of the complex between the molecules, were found to occur below pH 5.5 and above pH 8.5. The acid change, which was irreversible, was most likely caused by an irreversible conformational change of antithrombin. At alkaline pH, however, the gross conformation of antithrombin was stable up to pH 12, while the affinity of high-affinity heparin for antithrombin began to decrease markedly at pH 8.5. The dissociation curve, which was reversible, had a midpoint around pH 9.5. This is compatible with the loss of affinity being caused by either a local conformational change, by ionization of tyrosine or by titration of one or more amino groups. 相似文献