全文获取类型
收费全文 | 2842篇 |
免费 | 148篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 12篇 |
综合类 | 3篇 |
化学工业 | 737篇 |
金属工艺 | 31篇 |
机械仪表 | 16篇 |
建筑科学 | 131篇 |
矿业工程 | 4篇 |
能源动力 | 46篇 |
轻工业 | 482篇 |
水利工程 | 28篇 |
石油天然气 | 19篇 |
武器工业 | 1篇 |
无线电 | 130篇 |
一般工业技术 | 478篇 |
冶金工业 | 504篇 |
原子能技术 | 18篇 |
自动化技术 | 352篇 |
出版年
2023年 | 15篇 |
2022年 | 76篇 |
2021年 | 118篇 |
2020年 | 59篇 |
2019年 | 47篇 |
2018年 | 59篇 |
2017年 | 88篇 |
2016年 | 86篇 |
2015年 | 85篇 |
2014年 | 109篇 |
2013年 | 157篇 |
2012年 | 162篇 |
2011年 | 195篇 |
2010年 | 148篇 |
2009年 | 129篇 |
2008年 | 162篇 |
2007年 | 160篇 |
2006年 | 144篇 |
2005年 | 102篇 |
2004年 | 87篇 |
2003年 | 86篇 |
2002年 | 67篇 |
2001年 | 54篇 |
2000年 | 33篇 |
1999年 | 51篇 |
1998年 | 48篇 |
1997年 | 46篇 |
1996年 | 39篇 |
1995年 | 26篇 |
1994年 | 35篇 |
1993年 | 37篇 |
1992年 | 28篇 |
1991年 | 19篇 |
1990年 | 28篇 |
1989年 | 22篇 |
1988年 | 20篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 21篇 |
1984年 | 8篇 |
1983年 | 16篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 14篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 10篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1960年 | 5篇 |
排序方式: 共有2992条查询结果,搜索用时 15 毫秒
121.
Julia Welzenbach Christiane Neuhoff Hanna Heidt Mehmet Ulas Cinar Christian Looft Karl Schellander Ernst Tholen Christine Gro?e-Brinkhaus 《International journal of molecular sciences》2016,17(9)
The aim of this study was to integrate multi omics data to characterize underlying functional pathways and candidate genes for drip loss in pigs. The consideration of different omics levels allows elucidating the black box of phenotype expression. Metabolite and protein profiling was applied in Musculus longissimus dorsi samples of 97 Duroc × Pietrain pigs. In total, 126 and 35 annotated metabolites and proteins were quantified, respectively. In addition, all animals were genotyped with the porcine 60 k Illumina beadchip. An enrichment analysis resulted in 10 pathways, amongst others, sphingolipid metabolism and glycolysis/gluconeogenesis, with significant influence on drip loss. Drip loss and 22 metabolic components were analyzed as intermediate phenotypes within a genome-wide association study (GWAS). We detected significantly associated genetic markers and candidate genes for drip loss and for most of the metabolic components. On chromosome 18, a region with promising candidate genes was identified based on SNPs associated with drip loss, the protein “phosphoglycerate mutase 2” and the metabolite glycine. We hypothesize that association studies based on intermediate phenotypes are able to provide comprehensive insights in the genetic variation of genes directly involved in the metabolism of performance traits. In this way, the analyses contribute to identify reliable candidate genes. 相似文献
122.
Discovery of Highly Potent Dual Orexin Receptor Antagonists via a Scaffold‐Hopping Approach 下载免费PDF全文
Dr. Bibia Heidmann Dr. John Gatfield Dr. Catherine Roch Dr. Alexander Treiber Dr. Simone Tortoioli Dr. Christine Brotschi Dr. Jodi T. Williams Dr. Martin H. Bolli Dr. Stefan Abele Dr. Thierry Sifferlen Dr. François Jenck Dr. Christoph Boss 《ChemMedChem》2016,11(19):2132-2146
Starting from suvorexant (trade name Belsomra), we successfully identified interesting templates leading to potent dual orexin receptor antagonists (DORAs) via a scaffold‐hopping approach. Structure–activity relationship optimization allowed us not only to improve the antagonistic potency on both orexin 1 and orexin 2 receptors (Ox1 and Ox2, respectively), but also to increase metabolic stability in human liver microsomes (HLM), decrease time‐dependent inhibition of cytochrome P450 (CYP) 3A4, and decrease P‐glycoprotein (Pgp)‐mediated efflux. Compound 80 c [{(1S,6R)‐3‐(6,7‐difluoroquinoxalin‐2‐yl)‐3,8‐diazabicyclo[4.2.0]octan‐8‐yl}(4‐methyl‐[1,1′‐biphenyl]‐2‐yl)methanone] is a potent and selective DORA that inhibits the stimulating effects of orexin peptides OXA and OXB at both Ox1 and Ox2. In calcium‐release assays, 80 c was found to exhibit an insurmountable antagonistic profile at both Ox1 and Ox2, while displaying a sleep‐promoting effect in rat and dog models, similar to that of the benchmark compound suvorexant. 相似文献
123.
Dr. Gabriel E. Büchel Brandon Carney Travis M. Shaffer Dr. Jun Tang Dr. Christine Austin Prof. Manish Arora Prof. Brian M. Zeglis Prof. Jan Grimm Prof. Jörg Eppinger Prof. Thomas Reiner 《ChemMedChem》2016,11(18):1978-1982
Intraoperative imaging technologies recently entered the operating room, and their implementation is revolutionizing how physicians plan, monitor, and perform surgical interventions. In this work, we present a novel surgical imaging reporter system: intraoperative chemiluminescence imaging (ICI). To this end, we have leveraged the ability of a chemiluminescent metal complex to generate near‐infrared light upon exposure to an aqueous solution of Ce4+ in the presence of reducing tissue or blood components. An optical camera spatially resolves the resulting photon flux. We describe the construction and application of a prototype imaging setup, which achieves a detection limit as low as 6.9 pmol cm?2 of the transition‐metal‐based ICI agent. As a proof of concept, we use ICI for the in vivo detection of our transition metal tracer following both systemic and subdermal injections. The very high signal‐to‐noise ratios make ICI an interesting candidate for the development of new intraoperative imaging technologies. 相似文献
124.
Toon Verstraelen Bartłomiej M. Szyja David Lesthaeghe Reinout Declerck Veronique Van Speybroeck Michel Waroquier Antonius P. J. Jansen Alexander Aerts Lana R. A. Follens Johan A. Martens Christine E. A. Kirschhock Rutger A. van Santen 《Topics in Catalysis》2009,52(9):1261-1271
Zeolite synthesis is driven by structure-directing agents, such as tetrapropyl ammonium ions (TPA+) for Silicalite-1 and ZSM-5. However, the guiding role of these organic templates in the complex assembly to highly ordered
frameworks remains unclear, limiting the prospects for advanced material synthesis. In this work, both static ab initio and
dynamic classical modeling techniques are employed to provide insight into the interactions between TPA+ and Silicalite-1 precursors. We find that as soon as the typical straight 10-ring channel of Silicalite-1 or ZSM-5 is formed
from smaller oligomers, the TPA+ template is partially squeezed out of the resulting cavity. Partial retention of the template in the cavity is, however,
indispensable to prevent collapse of the channel and subsequent hydrolysis.
相似文献
Rutger A. van Santen (Corresponding author)Email: |
125.
Francesca Frati Keith Chamberlain Michael Birkett Samuel Dufour Patrick Mayon Christine Woodcock Lester Wadhams John Pickett Gianandrea Salerno Eric Conti Ferdinando Bin 《Journal of chemical ecology》2009,35(2):201-208
The profiles of volatile chemicals emitted by Vicia faba plants damaged by Lygus rugulipennis feeding, and by feeding plus oviposition, were shown to be quantitatively different from those released by undamaged plants.
Samples of volatile chemicals collected from healthy plants, plants damaged by males as a consequence of feeding, plants damaged
by females as a consequence of feeding and oviposition, plants damaged by feeding with mated males still present, and plants
damaged by feeding and oviposition with gravid females still present, showed significant differences in the emission of hexyl
acetate, (Z)-β-ocimene, (E)-β-ocimene, (E)-β-caryophyllene, and methyl salicylate. In particular, treatments with mated females present on plants had a significant
increase in emission levels of the above compounds, possibly due to eggs laid within plant tissues or active feeding, compared
with undamaged plants and plants damaged by males feeding, with or without insects still present. Furthermore, the pheromonal
blend released by mated L. rugulipennis females, mainly comprising hexyl butyrate, (E)-2-hexenyl butyrate, and (E)-4-oxo-2-hexenal, was enhanced when females were active on broad bean plants, whereas such an increase was not observed in
males. Both sexes gave electroantennogram responses to green leaf volatiles from undamaged plants and to methyl salicylate
and (E)-β-caryophyllene emitted by Lygus-damaged plants, suggesting that these compounds may be involved in colonization of host plants by L. rugulipennis. In addition, mated males and females were responsive to hexyl butyrate, (E)-2-hexenyl butyrate, and (E)-4-oxo-2-hexenal released by mated females on V. faba, indicating that these substances could have a dual function as a possible aggregation pheromone in female–female communication,
and as a sex pheromone in female–male communication.
An erratum to this article can be found at 相似文献
126.
Eric Favre Vronique Falk Christine Roizard Eric Schaer 《Education for Chemical Engineers》2008,3(1):e22-e27
Teaching chemical engineering has always been faced with a dilemma: either keep in touch with industry needs or incorporate new scientific concepts into the curriculum. In this paper, a short historical analysis of the evolution of chemical engineering teaching is presented and the recent trends of the two previous facets (industry and science) are briefly reviewed. The process vs product engineering concept is proposed as one of the means to achieve a better alignment between the curriculum and industry needs. A chemical engineering teaching framework, based in part on a product and a process oriented component, which has been in place in our department 5 years ago, is described and discussed. The concept of sustainable chemistry, including process and product considerations, which can be seen as the next frontier in chemical engineering education, is finally analysed from the education point of view. 相似文献
127.
Alessandri JM Extier A Langelier B Perruchot MH Heberden C Guesnet P Lavialle M 《Lipids》2008,43(1):19-28
Whether neurosteroids regulate the synthesis of long chain polyunsaturated fatty acids in brain cells is unknown. We examined
the influence of 17-β-estradiol (E2) on the capacity of SH-SY5Y cells supplemented with α-linolenic acid (ALA), to produce
eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). Cells were incubated for 24 or 72 h
with ALA added alone or in combination with E2 (ALA + E2). Fatty acids were analyzed by gas chromatography of ethanolamine
glycerophospholipids (EtnGpl) and phosphatidylcholine (PtdCho). Incubation for 24 h with ALA alone increased EPA and DPA in
EtnGpl, by 330 and 430% compared to controls (P < 0.001) and DHA by only 10% (P < 0.05). Although DHA increased by 30% (P < 0.001) in ALA + E2-treated cells, the difference between the ALA and ALA + E2 treatments were not significant after 24 h
(Anova-1, Fisher’s test). After 72 h, EPA, DPA and DHA further increased in EtnGpl and PtdCho of cells supplemented with ALA
or ALA + E2. Incubation for 72 h with ALA + E2 specifically increased EPA (+34% in EtnGpl, P < 0.001) and DPA (+15%, P < 0.001) compared to ALA alone. Thus, SH-SY5Y cells produced membrane EPA, DPA and DHA from supplemental ALA. The formation
of DHA was limited, even in the presence of E2. E2 significantly favored EPA and DPA production in cells grown for 72 h. Enhanced
synthesis of ALA-elongation products in neuroblastoma cells treated with E2 supports the hypothesis that neurosteroids could
modulate the metabolism of PUFA. 相似文献
128.
Schönrogge K Napper EK Birkett MA Woodcock CM Pickett JA Wadhams LJ Thomas JA 《Journal of chemical ecology》2008,34(2):168-178
The larva of the hoverfly Microdon mutabilis is a specialist social parasite of the ant Formica lemani that is adapted to local groups of F. lemani colonies but mal-adapted to colonies of the same species situated only a few hundred meters away. At a study site in Ireland,
F. lemani shares its habitat with four other ant species. All nest under stones, making the oviposition choice by M. mutabilis females crucial to offspring survival. In this study, we tested the hypothesis that, as an extreme specialist, M. mutabilis should respond to cues derived from its host rather than from its microenvironment, a phenomenon that has hitherto only been
addressed in the context of herbivorous insects and their parasitoids. In behavioral assays, M. mutabilis females reacted to volatiles from F. lemani colonies by extending their ovipositors, presumably probing for an oviposition substrate. This behavior was not observed
toward negative controls or volatiles from colonies of Myrmica scabrinodis, the host ant of the closely related Microdon myrmicae. Coupled gas chromatography-electroantennography (GC-EAG) that used antennal preparations of M. mutabilis located a single physiologically active compound within an extract of heads of F. lemani workers. Coupled GC-mass spectrometry (GC-MS) tentatively identified the compound as a methylated methylsalicylate. GC co-injection
of the extract with authentic samples showed that of the four possible isomers (methyl 3-, 4-, 5-, and 6-methylsalicylate),
only methyl 6-methylsalicylate co-eluted with the EAG-active peak. Furthermore, the response to methyl 6-methylsalicylate
was four times higher than to those of the other isomers. Coupled GC-EAG and GC-MS also revealed physiological responses to
two constituents, 3-octanone and 3-octanol, of the M. scabrinodis alarm pheromone. However, the behavioral trials did not reveal any behavior that could be attributed to these compounds.
Results are discussed in the context of four phases of host location behavior, and of the characteristics, which volatile
cues should provide to be useful for an extreme specialist such as M. mutabilis. 相似文献
129.
Crane CM Hirsch AK Alphey MS Sgraja T Lauw S Illarionova V Rohdich F Eisenreich W Hunter WN Bacher A Diederich F 《ChemMedChem》2008,3(1):91-101
The enzymes of the non-mevalonate pathway for isoprenoid biosynthesis are attractive targets for the development of novel drugs against malaria and tuberculosis. This pathway is used exclusively by the corresponding pathogens, but not by humans. A series of water-soluble, cytidine-based inhibitors that were originally designed for the fourth enzyme in the pathway, IspD, were shown to inhibit the subsequent enzyme, the kinase IspE (from Escherichia coli). The binding mode of the inhibitors was verified by co-crystal structure analysis, using Aquifex aeolicus IspE. The crystal structures represent the first reported example of a co-crystal structure of IspE with a synthetic ligand and confirmed that ligand binding affinity originates mainly from the interactions of the nucleobase moiety in the cytidine binding pocket of the enzyme. In contrast, the appended benzimidazole moieties of the ligands adopt various orientations in the active site and establish only poor intermolecular contacts with the protein. Defined binding sites for sulfate ions and glycerol molecules, components in the crystallization buffer, near the well-conserved ATP-binding Gly-rich loop of IspE were observed. The crystal structures of A. aeolicus IspE nicely complement the one from E. coli IspE for use in structure-based design, namely by providing invaluable structural information for the design of inhibitors targeting IspE from Mycobacterium tuberculosis and Plasmodium falciparum. Similar to the enzymes from these pathogens, A. aeolicus IspE directs the OH group of a tyrosine residue into a pocket in the active site. In the E. coli enzyme, on the other hand, this pocket is lined by phenylalanine and has a more pronounced hydrophobic character. 相似文献
130.
Johannes Klopf Christine Brostjan Wolf Eilenberg Christoph Neumayer 《International journal of molecular sciences》2021,22(2)
Neutrophils are primary effector cells of innate immunity and fight infection by phagocytosis and degranulation. Activated neutrophils also release neutrophil extracellular traps (NETs) in response to a variety of stimuli. These NETs are net-like complexes composed of cell-free DNA, histones and neutrophil granule proteins. Besides the evolutionarily conserved mechanism to capture and eliminate pathogens, NETs are also associated with pathophysiological processes of various diseases. Here, we elucidate the mechanisms of NET formation and their different implications in disease. We focused on autoinflammatory and cardiovascular disorders as the leading cause of death. Neutrophil extracellular traps are not only present in various cardiovascular diseases but play an essential role in atherosclerotic plaque formation, arterial and venous thrombosis, as well as in the development and progression of abdominal aortic aneurysms. Furthermore, NETosis can be considered as a source of autoantigens and maintains an inflammatory milieu promoting autoimmune diseases. Indeed, there is further need for research into the balance between NET induction, inhibition, and degradation in order to pharmacologically target NETs and their compounds without impairing the patient’s immune defense. This review may be of interest to both basic scientists and clinicians to stimulate translational research and innovative clinical approaches. 相似文献