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941.
Hao Wu Xiaolong Xu Dengke Shen Lili Peng Jiajia Song Yan Zhang 《Journal of biological inorganic chemistry》2011,16(1):69-79
Coagulation factor IX/coagulation factor X binding protein from the venom of Agkistrodon halys Pallas (AHP IX/X-bp) is a unique coagulation factor IX/coagulation factor X binding protein (IX/X-bp). Among all IX/X-bps
identified, only AHP IX/X-bp is a Ca2+- and Zn2+-binding protein. The binding properties of Ca2+ and Zn2+ ions binding to apo-AHP IX/X-bp and their effects on the stability of the protein have been investigated by isothermal titration
calorimetry, fluorescence spectroscopy, and differential scanning calorimetry. The results show that AHP IX/X-bp has two metal
binding sites, one specific for Ca2+ with lower affinity for Zn2+ and one specific for Zn2+ with lower affinity for Ca2+. The bindings of Ca2+ and Zn2+ in the two sites are entropy- and enthalpy-driven. The binding affinity of AHP IX/X-bp for Zn2+ is 1 order of magnitude higher than for Ca2+ for either high-affinity binding or low-affinity binding, which accounts for the existence of one Zn2+ in the purified AHP IX/X-bp. Guanidine hydrochloride (GdnHCl)-induced and thermally induced denaturations of Ca2+–Ca2+-AHP IX/X-bp, Zn2+–Zn2+-AHP IX/X-bp, and Ca2+–Zn2+-AHP IX/X-bp are all a two-state processes with no detectable intermediate state(s), indicating the Ca2+/Zn2+-induced tight packing of the protein. Ca2+ and Zn2+ increase the structural stability of AHP IX/X-bp against GdnHCl or thermal denaturation to a similar extent. Although Ca2+ and Zn2+ have no obvious effect on the secondary structure of AHP IX/X-bp, they induce different rearrangements in local conformation.
The Zn2+-stabilized specific conformation of AHP IX/X-bp may be helpful to its recognition of the structure of coagulation factor
IX. This work suggests that in vitro, Ca2+ plays a structural rather than an active role in the anticoagulation of AHP IX/X-bp, whereas Zn2+ plays both structural and active roles in the anticoagulation. In blood, Ca2+ binds to AHP IX/X-bp and stabilizes its structure, whereas Zn2+ cannot bind to AHP IX/X-bp owing to the low Zn2+ concentration. AHP IX/X-bp prolongs the clotting time in vivo through its binding only with coagulation factor X/activated
coagulation factor X. 相似文献
942.
The Golgi apparatus is an important eukaryotic organelle. Successful prediction of Golgi protein types can provide valuable information for elucidating protein functions involved in various biological processes. In this work, a method is proposed by combining a special mode of pseudo amino acid composition (increment of diversity) with the modified Mahalanobis discriminant for predicting Golgi protein types. The benchmark dataset used to train the predictor thus formed contains 95 Golgi proteins in which none of proteins included has ≥40% pairwise sequence identity to any other. The accuracy obtained by the jackknife test was 74.7%, with the ROC curve of 0.772 in identifying cis-Golgi proteins and trans-Golgi proteins. Subsequently, the method was extended to discriminate cis-Golgi network proteins from cis-Golgi network membrane proteins and trans-Golgi network proteins from trans-Golgi network membrane proteins, respectively. The accuracies thus obtained were 76.1% and 83.7%, respectively. These results indicate that our method may become a useful tool in the relevant areas. As a user-friendly web-server, the predictor is freely accessible at http://immunet.cn/SubGolgi/. 相似文献
943.
Introduction – Sinigrin, a major glucosinolate present in Indian mustard (Brassica juncea L.) seeds as the precursor of the anticancer compound allyl isothiocyanate, shows a wide range of biological activities. It's necessary to optimize the extraction methods and conditions, in order to improve the extraction productivity and save raw material. Objective – To systemically investigate and optimize the most important factors affected the productivity of sinigrin in the process of extraction using response surface methodology. Methodology – The ranges of three main factors including the ethanol concentration, extraction time and extraction temperature were selected by the one‐factor‐at‐a‐time method. The conditions of ultrasonic‐stimulated extraction of sinigrin from defatted Indian mustard seed powder were optimized by Box‐Behnken design to obtain the maximum productivity. Result – The predicted productivity (3.81%) was obtained using 57% ethanol concentration at 81°C for 60 min, with the coefficient of the model R2 > 0.96 (n = 17). The actual productivity (3.84 ± 0.02%) of sinigrin under the optimized condition was increased by 70.67% compared with the result of conventional extraction. Meanwhile, HPLC, UV and IR were applied to examine if there is a difference between the ultrasonic‐stimulated solvent extraction and conventional extraction, and the improvement of productivity of sinigrin depended on the destruction of cell wall caused by the elimination of outer pectinous material was explained by SEM and composition content analysis. Conclusion – The ultrasonic‐stimulated solvent extraction was suggested to be a promising method to improve the productivity of sinigrin. And the results demonstrated that sinigrin productivity may be related to pectinous materials existed in the seeds. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
944.
Chiemchaisri W Chiemchaisri C Dumrongsukit C Threedeach S Ngo HH Vigneswaran S 《Bioresource technology》2011,102(9):5438-5443
Floating plastic media pre-filter (PP) in combination with microfiltration membrane (MF) was applied to the removal of water-borne microorganism from surface water. The system was operated with and without coagulant addition. Jar-test results suggested that alum and polyaluminum chloride could effectively remove turbidity, fecal coliforms (FC) and algae at their optimum doses. Nevertheless, none of those coagulants could accomplish high coliphage (CP) removal. Microorganism removal in the system was increasing along with time in the PP unit operated at 5-m3/m2/h filtration rate but opposite trend was observed at higher filtration rates (10-15 m3/m2/h). Different coagulant types and filtration rates employed in the PP unit also affected microorganism removal in MF unit. The operation of PP unit at a filtration rate of 15 m3/m2/h and MF unit at a filtration rate of 0.6 m3/m2/d could achieve satisfactory turbidity and overall microorganism removal. 相似文献
945.
Acid tolerance of an acid mine drainage bioremediation system based on biological sulfate reduction 总被引:1,自引:0,他引:1
The acid tolerance response of an AMD bioremediation system based on sulfate reduction was investigated. Efficient sulfate reduction was observed with a maximum sulfate reduction rate of 12.3±0.8 mg L(-1) d(-1) and easily available organic carbon was released during high acid treatment with an initial pH of 2.0. The rapid increase in sulfate reduction was observed when the extreme acid treatment with an initial pH of 1.0 was stopped. Column experiment on acid shock showed that efficient sulfate reduction was maintained while precipitation of Cu or Zn still occurred during extreme or high acid shock. More than 98% of Cu and 85% of Zn were removed in the high acid column experiment with influent pH of 2.0. The majority bacteria in the remediation system used for high acid drainage belonged to genera Clostridiaceae, Eubacterium, Pseudobutyrivibrio, and Clostridium. These findings showed high acid tolerance of the straw remediation system. 相似文献
946.
Qiu H Nomiyama R Moriguchi K Fukada T Sugimoto K 《Bioscience, biotechnology, and biochemistry》2011,75(1):145-147
Since certain missense mutations in the N-terminal part of filamin A (FLNA) cause inherited skeletal malformation, we screened for proteins that bind to this part of FLNA. We identified two nuclear proteins that are specifically associated with the N-terminal region of FLNA. This suggests more extensive nuclear function of filamin than expected. 相似文献
947.
Biodiesel production from rubber seed oil using poly (sodium acrylate) supporting NaOH as a water-resistant catalyst 总被引:1,自引:0,他引:1
Poly (sodium acrylate) supporting NaOH (NaOH/NaPAA) was prepared by in situ polymerization of aqueous solution of acrylic acid with an over-neutralization by adding excess of NaOH. NaOH/NaPAA presented a promising selectivity for water absorbency and good water retention with negligible swelling capacity in the organic solvents of methanol, glycerol, rubber seed oil methyl esters, and rubber seed oil. NaOH/NaPAA catalysts showed a basic strength of 15.0 < H_ < 18.4 and their basicity increased with the increase of the NaOH loading amount. NaOH/NaPAA catalysts exhibited almost the same catalytic activity in the transesterification of rubber seed oil with methanol under the optimized reaction conditions compared to conventional homogeneous NaOH catalyst. Furthermore, the functional absorbent/catalyst system presented a good water resistance in the transesterification which retained high catalytic activity when a water concentration in the reaction system was less than 2 wt.%. 相似文献
948.
Guiyang Hao Jian Zhou Yi Guo Michael A. Long Tiffani Anthony Jennifer Stanfield Jer-Tsong Hsieh Xiankai Sun 《Amino acids》2011,41(5):1093-1101
Non-invasive detection of prostate cancer or metastases still remains a challenge in the field of molecular imaging. In our
recent work of screening arginine- or lysine-rich peptides for intracellular delivery of a therapeutic agent into prostate
cancer cells, an arginine-rich cell permeable peptide (NH2GR11) was found with an unexpectedly preferential uptake in prostate cancer cell lines. The goal of this work was to develop this
peptide as a positron emission tomography (PET) imaging probe for specific detection of distant prostate cancer metastases.
The optimal length of arginine-rich peptides was evaluated by the cell uptake efficiency of three fluorescein isothiocyanate
(FITC)-tagged oligoarginines (NHGR9, NHGR11, and NHGR13) in four human prostate cell lines (LNCaP, PZ-HPV-7, DU145, and PC3). Of the three oligoarginines, NH2GR11 showed the highest cell uptake and internalization efficiency with its subcellular localization in cytosol. The biodistribution
of FITC-NHGR9, FITC-NHGR11, and FITC-NHGR13 performed in control nude mice displayed the unique preferential accumulation of FITC-NHGR11 in the prostate tissue. Further in vivo evaluation of FITC-NHGR11 in PC3 tumor-bearing nude mice revealed elevated uptake of this peptide in tumors as compared to other organs. In vivo pharmacokinetics
evaluated with 64Cu-labeled NH2GR11 showed that the peptide was rapidly cleared from the blood (t
1/2 = 10.7 min) and its elimination half-life was 17.2 h. The PET imaging specificity of 64Cu-labled NH2GR11 was demonstrated for the detection of prostate cancer in a comparative imaging experiment using two different human cancer
xenograft models. 相似文献
949.
Computational protein structure prediction remains a challenging task in protein bioinformatics. In the recent years, the importance of template-based structure prediction is increasing because of the growing number of protein structures solved by the structural genomics projects. To capitalize the significant efforts and investments paid on the structural genomics projects, it is urgent to establish effective ways to use the solved structures as templates by developing methods for exploiting remotely related proteins that cannot be simply identified by homology. In this work, we examine the effect of using suboptimal alignments in template-based protein structure prediction. We showed that suboptimal alignments are often more accurate than the optimal one, and such accurate suboptimal alignments can occur even at a very low rank of the alignment score. Suboptimal alignments contain a significant number of correct amino acid residue contacts. Moreover, suboptimal alignments can improve template-based models when used as input to Modeller. Finally, we use suboptimal alignments for handling a contact potential in a probabilistic way in a threading program, SUPRB. The probabilistic contacts strategy outperforms the partly thawed approach, which only uses the optimal alignment in defining residue contacts, and also the re-ranking strategy, which uses the contact potential in re-ranking alignments. The comparison with existing methods in the template-recognition test shows that SUPRB is very competitive and outperforms existing methods. 相似文献
950.
Lü S Luo Q Hao X Li X Ji L Zheng W Wang F 《Bioorganic & medicinal chemistry letters》2011,21(23):6964-6968
Six analogs of imatinib, an Abl kinase inhibitor clinically used as a first-line therapeutic agent for chronic myeloid leukaemia (CML), have been synthesized and characterized. And their potency as Abl kinase inhibitors have been screened by a robust virtual screening method developed based on the crystal structure (PDB code 2hyy) of Abl-imatinib complex using Surflex-Docking. The docking results are consistent with the inhibitory potency of the compounds characterized by MS method. And the H-bonds between imatinib analogs and Thr315 and Met318 residues in Abl kinase are shown to be crucial for achieving accurate poses and high binding affinities for the ATP-competitive kinase inhibitors. 相似文献