全文获取类型
收费全文 | 16835篇 |
免费 | 2146篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 1361篇 |
综合类 | 403篇 |
化学工业 | 8481篇 |
金属工艺 | 245篇 |
机械仪表 | 377篇 |
建筑科学 | 642篇 |
矿业工程 | 167篇 |
能源动力 | 91篇 |
轻工业 | 1699篇 |
水利工程 | 116篇 |
石油天然气 | 68篇 |
无线电 | 334篇 |
一般工业技术 | 2836篇 |
冶金工业 | 142篇 |
原子能技术 | 25篇 |
自动化技术 | 1999篇 |
出版年
2023年 | 619篇 |
2022年 | 305篇 |
2021年 | 654篇 |
2020年 | 658篇 |
2019年 | 572篇 |
2018年 | 545篇 |
2017年 | 379篇 |
2016年 | 600篇 |
2015年 | 776篇 |
2014年 | 807篇 |
2013年 | 1383篇 |
2012年 | 522篇 |
2011年 | 395篇 |
2010年 | 752篇 |
2009年 | 902篇 |
2008年 | 400篇 |
2007年 | 368篇 |
2006年 | 267篇 |
2005年 | 261篇 |
2004年 | 213篇 |
2003年 | 201篇 |
1998年 | 176篇 |
1997年 | 131篇 |
1996年 | 194篇 |
1995年 | 182篇 |
1994年 | 156篇 |
1993年 | 219篇 |
1992年 | 152篇 |
1991年 | 122篇 |
1990年 | 151篇 |
1989年 | 173篇 |
1988年 | 136篇 |
1987年 | 161篇 |
1986年 | 182篇 |
1985年 | 164篇 |
1984年 | 167篇 |
1983年 | 175篇 |
1982年 | 155篇 |
1981年 | 202篇 |
1980年 | 165篇 |
1979年 | 169篇 |
1977年 | 147篇 |
1976年 | 149篇 |
1975年 | 202篇 |
1974年 | 188篇 |
1973年 | 365篇 |
1972年 | 212篇 |
1971年 | 150篇 |
1970年 | 144篇 |
1968年 | 153篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Importance of a Conserved Lys/Arg Residue for Ligand/PDZ Domain Interactions as Examined by Protein Semisynthesis 下载免费PDF全文
Dr. Søren W. Pedersen Griffin E. Moran Vita Sereikaitė Dr. Linda M. Haugaard‐Kedström Prof. Dr. Kristian Strømgaard 《Chembiochem : a European journal of chemical biology》2016,17(20):1936-1944
PDZ domains are ubiquitous small protein domains that are mediators of numerous protein–protein interactions, and play a pivotal role in protein trafficking, synaptic transmission, and the assembly of signaling‐transduction complexes. In recent years, PDZ domains have emerged as novel and exciting drug targets for diseases (in the brain in particular), so understanding the molecular details of PDZ domain interactions is of fundamental importance. PDZ domains bind to a protein partner at either a C‐terminal peptide or internal peptide motifs. Here, we examined the importance of a conserved Lys/Arg residue in the ligand‐binding site of the second PDZ domain of PSD‐95, by employing a semisynthetic approach. We generated six semisynthetic PDZ domains comprising different proteogenic and nonproteogenic amino acids representing subtle changes of the conserved Lys/Arg residue. These were tested with four peptide interaction partners, representing the two different binding modes. The results highlight the role of a positively charged amino acid in the β1–β2 loop of PDZ domains, and show subtle differences for canonical and noncanonical interaction partners, thus providing additional insight into the mechanism of PDZ/ligand interaction. 相似文献
982.
Greg Mann Dr. Liujie Huo Sebastian Adam Dr. Brunello Nardone Dr. Jeremie Vendome Prof. Nicholas James Westwood Prof. Rolf Müller Dr. Jesko Koehnke 《Chembiochem : a European journal of chemical biology》2016,17(23):2286-2292
The bottromycins are a family of highly modified peptide natural products, which display potent antimicrobial activity against Gram‐positive bacteria, including methicillin‐resistant Staphylococcus aureus. Bottromycins have recently been shown to be ribosomally synthesized and post‐translationally modified peptides (RiPPs). Unique amongst RiPPs, the precursor peptide BotA contains a C‐terminal “follower” sequence, rather than the canonical N‐terminal “leader” sequence. We report herein the structural and biochemical characterization of BotP, a leucyl‐aminopeptidase‐like enzyme from the bottromycin pathway. We demonstrate that BotP is responsible for the removal of the N‐terminal methionine from the precursor peptide. Determining the crystal structures of both apo BotP and BotP in complex with Mn2+ allowed us to model a BotP/substrate complex and to rationalize substrate recognition. Our data represent the first step towards targeted compound modification to unlock the full antibiotic potential of bottro‐ mycin. 相似文献
983.
Inside Cover: Hydrophilic trans‐Cyclooctenylated Noncanonical Amino Acids for Fast Intracellular Protein Labeling (ChemBioChem 16/2016) 下载免费PDF全文
984.
Amanda J. Cox Hillary N. Bengtson Dr. Yulia V. Gerasimova Dr. Kyle H. Rohde Dr. Dmitry M. Kolpashchikov 《Chembiochem : a European journal of chemical biology》2016,17(21):2038-2041
Some natural enzymes increase the rate of diffusion‐limited reactions by facilitating substrate flow to their active sites. Inspired by this natural phenomenon, we developed a strategy for efficient substrate delivery to a deoxyribozyme (DZ) catalytic sensor. This resulted in a three‐ to fourfold increase in sensitivity and up to a ninefold improvement in the detection limit. The reported strategy can be used to enhance catalytic efficiency of diffusion‐limited enzymes and to improve sensitivity of enzyme‐based biosensors. 相似文献
985.
DNA‐Templated Synthesis of Perylenediimide Stacks Utilizing Abasic Sites as Binding Pockets and Reactive Sites 下载免费PDF全文
Dr. Tadao Takada Misa Ido Akane Ashida Dr. Mitsunobu Nakamura Prof. Kazushige Yamana 《Chembiochem : a European journal of chemical biology》2016,17(23):2230-2233
DNA is considered to be a promising biomolecule as a template and scaffold for arranging and organizing functional molecules on the nanoscale. The construction and evaluation of DNAs containing multiple functional molecules that are useful for optoelectronic devices and sensors has been studied. In this paper we report the efficient incorporation of perylenediimide (PDI) units into DNA by using abasic sites both as binding sites and as reactive sites and the construction of PDI stacks within the DNA structure, accomplished through the preorganization of the PDI units in the hydrophobic pocket within the DNA. Our approach could become a valuable method for construction of DNA/chromophore hybrid structures potentially useful for the design of DNA‐based devices and biosensors. 相似文献
986.
Back Cover: Tailored Synthesis of 162‐Residue S‐Monoglycosylated GM2‐Activator Protein (GM2AP) Analogues that Allows Facile Access to a Protein Library (ChemBioChem 20/2016) 下载免费PDF全文
987.
988.
Cover Picture: DNA Antenna Tile‐Associated Deoxyribozyme Sensor with Improved Sensitivity (ChemBioChem 21/2016) 下载免费PDF全文
989.
Inside Cover: Site‐Specific Immobilization of the Peptidoglycan Synthase PBP1B on a Surface Plasmon Resonance Chip Surface (ChemBioChem 23/2016) 下载免费PDF全文
990.
11C‐ and 18F‐Labeled Radioligands for P‐Glycoprotein Imaging by Positron Emission Tomography 下载免费PDF全文
Dr. Mariangela Cantore Marcel Benadiba Philip H. Elsinga Chantal Kwizera Rudi A. J. O. Dierckx Nicola Antonio Colabufo Gert Luurtsema 《ChemMedChem》2016,11(1):108-118
P‐Glycoprotein (P‐gp) is an efflux transporter widely expressed at the human blood–brain barrier. It is involved in xenobiotics efflux and in onset and progression of neurodegenerative disorders. For these reasons, there is great interest in the assessment of P‐gp expression and function by noninvasive techniques such as positron emission tomography (PET). Three radiolabeled aryloxazole derivatives: 2‐[2‐(2‐methyl‐(11C)‐5‐methoxyphenyl)oxazol‐4‐ylmethyl]‐6,7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinoline ([11C]‐ 5 ); 2‐[2‐(2‐fluoromethyl‐(18F)‐5‐methoxyphenyl)oxazol‐4‐ylmethyl]‐6,7‐dimethoxy‐1,2,3,4‐tetra‐hydroisoquinoline ([18F]‐ 6 ); and 2‐[2‐(2‐fluoroethyl‐(18F)‐5‐methoxyphenyl)oxazol‐4‐ylmethyl]‐6,7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinoline ([18F]‐ 7 ), were tested in several in vitro biological assays to assess the effect of the aryl substituent in terms of potency and mechanism of action toward P‐gp. Methyl derivative [11C]‐ 5 is a potent P‐gp substrate, whereas the corresponding fluoroethyl derivative [18F]‐ 7 is a P‐gp inhibitor. Fluoromethyl compound [18F]‐ 6 is classified as a non‐transported P‐gp substrate, because its efflux increases after cyclosporine A modulation. These studies revealed a promising substrate and inhibitor, [11C]‐ 5 and [18F]‐ 7 , respectively, for in vivo imaging of P‐gp by using PET. 相似文献