全文获取类型
收费全文 | 2581篇 |
免费 | 412篇 |
国内免费 | 65篇 |
专业分类
综合类 | 84篇 |
化学工业 | 784篇 |
金属工艺 | 21篇 |
机械仪表 | 69篇 |
建筑科学 | 14篇 |
能源动力 | 1篇 |
轻工业 | 1752篇 |
水利工程 | 1篇 |
石油天然气 | 7篇 |
无线电 | 69篇 |
一般工业技术 | 192篇 |
冶金工业 | 5篇 |
原子能技术 | 22篇 |
自动化技术 | 37篇 |
出版年
2024年 | 15篇 |
2023年 | 93篇 |
2022年 | 122篇 |
2021年 | 287篇 |
2020年 | 164篇 |
2019年 | 154篇 |
2018年 | 132篇 |
2017年 | 135篇 |
2016年 | 115篇 |
2015年 | 140篇 |
2014年 | 123篇 |
2013年 | 176篇 |
2012年 | 244篇 |
2011年 | 209篇 |
2010年 | 129篇 |
2009年 | 135篇 |
2008年 | 107篇 |
2007年 | 104篇 |
2006年 | 115篇 |
2005年 | 86篇 |
2004年 | 60篇 |
2003年 | 53篇 |
2002年 | 41篇 |
2001年 | 22篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1980年 | 5篇 |
1977年 | 1篇 |
排序方式: 共有3058条查询结果,搜索用时 187 毫秒
71.
Long‐term expansion of human induced pluripotent stem cells in a microcarrier‐based dynamic system 下载免费PDF全文
72.
High‐pressure microfluidisation pretreatment disaggregate peanut protein isolates to prepare antihypertensive peptide fractions 下载免费PDF全文
Kuijie Gong Lei Deng Aimin Shi Hongzhi Liu Li Liu Hui Hu Benu Adhikari Qiang Wang 《International Journal of Food Science & Technology》2017,52(8):1760-1769
High‐pressure microfluidisation (HPM) pretreatment was applied to increase in vitro antihypertensive activity of peanut peptide fractions (PPF). The morphology of protein in aqueous dispersion revealed that peanut protein isolate (PPI) disaggregated at relatively low pressure (≤120 MPa) and re‐aggregated at relatively high pressures (150–210 MPa). The treated pressure of 120 MPa could lead to the most disaggregation of PPI. Small peptides contents, trichloroacetic acid‐nitrogen soluble index (TCA‐NSI) and degree of hydrolysis (DH) of peanut protein hydrolysates (PPH) all reached the highest at 120 MPa. Consequently, it possessed the highest angiotensin converting enzyme (ACE) and renin inhibitory activity. The highest surface hydrophobicity occurred at 120 MPa pretreatment samples. Thirty‐nine oligopeptides at 120 MPa pretreatment were identified by ultra‐performance liquid chromatography‐quadrupole time‐of‐flight (UPLC‐Q‐TOF) mass spectrometer combined with Progenesis QI for Proteomics software compared with 29 and 35 at control and 210 MPa, respectively. This meant that disaggregation of PPI at 120 MPa resulted in the release of new hydrophobic peptide. 相似文献
73.
A simple and facile approach to impart the antifouling properties of silicone hydrogels was developed in this report. Short peptides were first tethered to silicone hydrogels through terminal amino group-induced epoxy ring-opening click reaction. The modified silicone hydrogels have improved hydrophilicity and protein adsorption resistance because of the formation of zwitterionic structure of the grafted peptides. Furthermore, glycylglycine and diglycyl glycine-modified silicone hydrogel contact lenses were fabricated. They exhibited favorable antifouling property and no damage to rabbits’ eyes after continuous wearing. The short peptide modified silicone hydrogel contact lenses have potential application in ophthalmology. 相似文献
74.
Kate Ryan Sabine M. Neumayer Harsha Vardhan R. Maraka Nicolae-Viorel Buchete Andrei L. Kholkin James H. Rice 《Science and Technology of Advanced Materials》2013,14(1):172-179
AbstractNanocomposites of diphenylalanine (FF) and carbon based materials provide an opportunity to overcome drawbacks associated with using FF micro- and nanostructures in nanobiotechnology applications, in particular their poor structural stability in liquid solutions. In this study, FF/graphene oxide (GO) composites were found to self-assemble into layered micro- and nanostructures, which exhibited improved thermal and aqueous stability. Dependent on the FF/GO ratio, the solubility of these structures was reduced to 35.65% after 30 min as compared to 92.4% for pure FF samples. Such functional nanocomposites may extend the use of FF structures to e.g. biosensing, electrochemical, electromechanical or electronic applications. 相似文献
75.
Shabana Vohra Bruck Taddese Alex C. Conner David R. Poyner Debbie L. Hay James Barwell Philip J. Reeves Graham J. G. Upton Christopher A. Reynolds 《Journal of the Royal Society Interface》2013,10(79)
Modelling class B G-protein-coupled receptors (GPCRs) using class A GPCR structural templates is difficult due to lack of homology. The plant GPCR, GCR1, has homology to both class A and class B GPCRs. We have used this to generate a class A–class B alignment, and by incorporating maximum lagged correlation of entropy and hydrophobicity into a consensus score, we have been able to align receptor transmembrane regions. We have applied this analysis to generate active and inactive homology models of the class B calcitonin gene-related peptide (CGRP) receptor, and have supported it with site-directed mutagenesis data using 122 CGRP receptor residues and 144 published mutagenesis results on other class B GPCRs. The variation of sequence variability with structure, the analysis of polarity violations, the alignment of group-conserved residues and the mutagenesis results at 27 key positions were particularly informative in distinguishing between the proposed and plausible alternative alignments. Furthermore, we have been able to associate the key molecular features of the class B GPCR signalling machinery with their class A counterparts for the first time. These include the [K/R]KLH motif in intracellular loop 1, [I/L]xxxL and KxxK at the intracellular end of TM5 and TM6, the NPXXY/VAVLY motif on TM7 and small group-conserved residues in TM1, TM2, TM3 and TM7. The equivalent of the class A DRY motif is proposed to involve Arg2.39, His2.43 and Glu3.46, which makes a polar lock with T6.37. These alignments and models provide useful tools for understanding class B GPCR function. 相似文献
76.
Anja S. GoldmannLeonie Barner Michael KauppAndrew P. Vogt Christopher Barner-Kowollik 《Progress in Polymer Science》2012,37(7):975-984
Modular ligation strategies for the functionalization of polymeric microspheres provide new perspectives for their applications in material science. In the current trend article we highlight variable synthetic procedures for generating functional microspheres via orthogonal modular conjugation chemistries. An overview of the different surface chemistries available is provided, followed by surface-sensitive characterization techniques relevant for the microparticles. Finally, we explore future trends in modular orthogonal modification approaches on microparticles and provide an outlook on the perspectives that the field of surface-modification of polymeric microparticles holds. 相似文献
77.
《Food Control》2016
Previously, we have isolated a novel bacteriocin, peptide F1 from Tibetan Kefir, and demonstrated its superior antimicrobial activity. However, its antimicrobial mechanism is still undefined. This study was aimed to elucidate the antimicrobial mechanism of peptide F1 against Staphylococcus aureus. The antimicrobial effects of peptide F1 were characterized by the following methods: chemical assay to quantify cytoplasmic β-galactosidase leakage, atomic absorption spectrometry to measure the released potassium ions, transmission electron microscopy to visualize the cellular morphological changes, and electrophoresis analysis and atomic force microscopy together to exam the DNA binding activity. Our results revealed that peptide F1 exerted its bactericidal effects by damaging bacterial cell membranes and by binding to the genomic DNA in the cytoplasm, which both led to rapid cell death. 相似文献
78.
Philip J. Kuehl Tracey Boyden Dan E. Dobry Melanie Doyle-Eisele Dwayne T. Friesen Jacob D. McDonald 《Drug development and industrial pharmacy》2016,42(1):150-156
Objective: Peptide YY3–36 [PYY(3–36)] has shown efficacy in appetite suppression when dosed by injection modalities (intraperitoneal (IP)/subcutaneous). Transitioning to needle-free delivery, towards inhalation, often utilizes systemic pharmacokinetics as a key endpoint to compare different delivery methods and doses. Systemic pharmacokinetics were evaluated for PYY3–36 when delivered by IP, subcutaneous, and inhalation, the systemic pharmacokinetics were then used to select doses in an appetite suppression pharmacodynamic study.Methods: Dry-powder formulations were manufactured by spray drying and delivered to mice via nose only inhalation. The systemic plasma, lung tissue, and bronchoalveolar lavage fluid pharmacokinetics of different inhalation doses of PYY(3–36) were compared to IP and subcutaneous efficacious doses. Based on these pharmacokinetic data, inhalation doses of 70:30 PYY(3–36):Dextran T10 were evaluated in a mouse model of appetite suppression and compared to IP and subcutaneous data.Results: Inhalation pharmacokinetic studies showed that plasma exposure was similar for a 2?×?higher inhalation dose when compared to subcutaneous and IP delivery. Inhalation doses of 0.22 and 0.65?mg/kg were for efficacy studies. The results showed a dose-dependent (not dose proportional) decrease in food consumption over 4?h, which is similar to IP and subcutaneous delivery routes.Conclusions: The pharmacokinetic and pharmacodynamics results substantiate the ability of pharmacokinetic data to inform pharmacodynamics dose selection for inhalation delivery of the peptide PYY(3–36). Additionally, engineered PYY(3–36):Dextran T10 particles delivered to the respiratory tract show promise as a non-invasive therapeutic for appetite suppression. 相似文献
79.
80.
Optimization of enzymatic hydrolysis parameters for antioxidant capacity of peptide from goat placenta 总被引:4,自引:0,他引:4
The goat placenta protein was hydrolyzed by pepsin and the optimal hydrolysis parameters of strongest antioxidant capacity of peptides were obtained using response surface methodology (RSM). The effects of reaction temperature, pH value and enzyme to substrate (E:S) ratio on the reducing power (RP) of the peptides and degree of hydrolysis (DH) of protein were well fitted to a quadric equation with high determination coefficients. The hydrolysate with optimal RP was predicted to be obtained at: temperature of 36.5 °C, pH value of 1.05, and E:S ratio of 2.03% and 3–10 kDa fraction (10 mg/mL), rich in GLY, GLU, ASP and TYR, was proved to exhibit highest RP, which is equivalent to the RP of 0.189 mg/mL ascorbic acid. The fraction of peptide also showed peroxidation inhibition in linoleic acid oxidation system and had a free radical scavenging ability similar to ascorbic acid (10 μg/mL) in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) system after 17 min. 相似文献