全文获取类型
收费全文 | 155篇 |
免费 | 17篇 |
专业分类
电工技术 | 1篇 |
综合类 | 1篇 |
化学工业 | 34篇 |
金属工艺 | 1篇 |
机械仪表 | 1篇 |
建筑科学 | 3篇 |
能源动力 | 8篇 |
轻工业 | 39篇 |
石油天然气 | 2篇 |
无线电 | 17篇 |
一般工业技术 | 16篇 |
冶金工业 | 27篇 |
原子能技术 | 1篇 |
自动化技术 | 21篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 3篇 |
2015年 | 9篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 6篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 16篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有172条查询结果,搜索用时 15 毫秒
91.
A–D–A‐Type Oligothiophenes for Small Molecule Organic Solar Cells: Extending the π‐System by Introduction of Ring‐Locked Double Bonds 下载免费PDF全文
Roland Fitzner Elena Mena‐Osteritz Karsten Walzer Martin Pfeiffer Peter Bäuerle 《Advanced functional materials》2015,25(12):1845-1856
A series of novel acceptor–donor–acceptor oligothiophenes terminally substituted with the 1‐(1,1‐dicyanomethylene)‐cyclohex‐2‐ene (DCC) acceptor has been synthesized. Structural, thermal, optoelectronic, and photovoltaic properties of the π‐extended DCCnTs (n = 1–4) are characterized and contrasted to the trends found for the series of parent dicyanovinyl (DCV)‐substituted oligothiophenes DCVnT. The optoelectronic properties reveal the influence of the additional exocyclic, sterically fixed double bonds in trans‐configuration in the novel DCCnT derivatives. A close correspondence for derivatives with equal number of double bonds, that is, DCCnTs and DCV(n + 1)Ts, is identified. Despite having the same energy gap, the energy levels of the frontier orbitals, HOMO and LUMO, for the DCC ‐ derivatives are raised and more destabilized due to the aromatization energy of a thiophene ring versus two exocyclic double bonds indicating improved donor and reduced acceptor strength. DCC‐terthiophenes give good photovoltaic performance as donor materials in vacuum‐processed solar cells (power conversion efficiencies ≤ 4.4%) clearly outperforming all comparable DCV4T derivatives. 相似文献
92.
Claudio Curti Nicoletta Brindani Lucia Battistini Andrea Sartori Giorgio Pelosi Pedro Mena Furio Brighenti Franca Zanardi Daniele DelRio 《Advanced Synthesis \u0026amp; Catalysis》2015,357(18):4082-4092
The asymmetric synthesis of a set of hydroxyphenyl γ‐valerolactones was achieved starting from 2‐silyloxyfuran and alkoxy‐substituted benzaldehydes as common precursors. Key synthesis steps included an enantioselective vinylogous Mukaiyama aldol reaction and a Barton–McCombie deoxygenation. Five enantioenriched γ‐valerolactone targets were obtained in 5–6 steps, 18–63% overall yields and 82–98 % ee, paving the way for the straightforward entry to this class of biologically effective and poorly available flavan‐3‐ol metabolites. In parallel, an unprecedented one‐pot reductive ring expansion process was fortuitously discovered, yielding racemic δ‐lactone analogues from phenolic butanolide precursors.
93.
A–D–A‐type S,N‐Heteropentacenes: Next‐Generation Molecular Donor Materials for Efficient Vacuum‐Processed Organic Solar Cells 下载免费PDF全文
94.
95.
The effects of feeding varying amounts of gossypol from whole cottonseed and cottonseed meal in lactating dairy cows. 总被引:1,自引:0,他引:1
H Mena J E Santos J T Huber J M Simas M Tarazon M C Calhoun 《Journal of dairy science》2001,84(10):2231-2239
Effects of feeding varying amounts of total gossypol from whole cottonseed and cottonseed meal were evaluated in 30 lactating Holstein cows. After a 14-d pretreatment period, cows were assigned for 42 d to one of five treatments: control (diet A); 1040 mg/kg of total gossypol, and 989 mg/kg of free gossypol from whole cottonseed (diet B); 900 mg/kg of total gossypol and 64 mg/kg of free gossypol from cottonseed meal (diet C); 960 mg/kg of total gossypol and 531 mg/kg of free gossypol with equal amounts of total gossypol from whole cottonseed and cottonseed meal (diet D); or 1922 mg/kg of total gossypol and 1050 mg/kg of free gossypol with equal amounts of total gossypol from whole cottonseed and cottonseed meal (diet E). Concentrations of plasma gossypol and its isomers were directly proportional to free gossypol intake. Plasma gossypol concentrations plateaued after 35 d on treatment, and they were highest in cows receiving diet E. At 42 d on treatment, erythrocyte fragility was higher in the cows receiving the diet E, but it did not differ among other treatments. Dry matter intakes were similar for all groups. Cows receiving diet E produced more milk and 3.5% fat-corrected milk, but milk protein content decreased. Feeding diets containing 1900 mg/kg of total gossypol and 1050 mg/kg of free gossypol for 42 d resulted in increased plasma gossypol concentrations and erythrocyte fragility, but no detrimental impact on lactation performance were observed. 相似文献
96.
A new multiple-resistivity drift-region structure which leads to an improvement of the on-resistance of high voltage LDMOS devices is proposed. The distinctive feature of the novel structure is the low sensitivity of the breakdown voltage to process variations. The important parameters of the structure such as on-resistance, threshold voltage and punchthrough voltage in the channel are discussed, and related to breakdown voltage. Experimental structures are fabricated and characterized to illustrate the advantages of the structure. 相似文献
97.
Shane N. Berger Beatrice Baumberger Srimal Samaranayake Melinda Hersey Sergio Mena Ian Bain William Duncan Michael C. Reed H. Frederik Nijhout Janet Best Parastoo Hashemi 《International journal of molecular sciences》2022,23(23)
Histamine is well known for mediating peripheral inflammation; however, this amine is also found in high concentrations in the brain where its roles are much less known. In vivo chemical dynamics are difficult to measure, thus fundamental aspects of histamine’s neurochemistry remain undefined. In this work, we undertake the first in-depth characterization of real time in vivo histamine dynamics using fast electrochemical tools. We find that histamine release is sensitive to pharmacological manipulation at the level of synthesis, packaging, autoreceptors and metabolism. We find two breakthrough aspects of histamine modulation. First, differences in H3 receptor regulation between sexes show that histamine release in female mice is much more tightly regulated than in male mice under H3 or inflammatory drug challenge. We hypothesize that this finding may contribute to hormone-mediated neuroprotection mechanisms in female mice. Second, a high dose of a commonly available antihistamine, the H1 receptor inverse agonist diphenhydramine, rapidly decreases serotonin levels. This finding highlights the sheer significance of pharmaceuticals on neuromodulation. Our study opens the path to better understanding and treating histamine related disorders of the brain (such as neuroinflammation), emphasizing that sex and modulation (of serotonin) are critical factors to consider when studying/designing new histamine targeting therapeutics. 相似文献
98.
Paul Ritter Stefanie Nübler Andreas Buttgereit Lucas R. Smith Alexander Mühlberg Julian Bauer Mena Michael Lucas Kreiß Michael Haug Elisabeth Barton Oliver Friedrich 《International journal of molecular sciences》2022,23(18)
Duchenne muscular dystrophy (DMD) is a degenerative genetic myopathy characterized by complete absence of dystrophin. Although the mdx mouse lacks dystrophin, its phenotype is milder compared to DMD patients. The incorporation of a null mutation in the Cmah gene led to a more DMD-like phenotype (i.e., more fibrosis). Although fibrosis is thought to be the major determinant of ‘structural weakness’, intracellular remodeling of myofibrillar geometry was shown to be a major cellular determinant thereof. To dissect the respective contribution to muscle weakness, we assessed biomechanics and extra- and intracellular architecture of whole muscle and single fibers from extensor digitorum longus (EDL) and diaphragm. Despite increased collagen contents in both muscles, passive stiffness in mdx Cmah diaphragm was similar to wt mice (EDL muscles were twice as stiff). Isometric twitch and tetanic stresses were 50% reduced in mdx Cmah diaphragm (15% in EDL). Myofibrillar architecture was severely compromised in mdx Cmah single fibers of both muscle types, but more pronounced in diaphragm. Our results show that the mdx Cmah genotype reproduces DMD-like fibrosis but is not associated with changes in passive visco-elastic muscle stiffness. Furthermore, detriments in active isometric force are compatible with the pronounced myofibrillar disarray of the dystrophic background. 相似文献
99.
Salvador A. Snchez‐Tovar Alfredo Salazar‐Zazueta Baltasar Mena‐Iniesta Carmen Durn‐de‐Bazúa 《Starch - St?rke》2004,56(11):526-534
Mexicans staple food is maize “tortilla”, prepared by thermal‐alkaline processes. The sensory properties of “masa” and “tortilla” depend on the reactions occuring between lime and chemical compounds in maize. In the present study, the effect of different calcium hydroxide, Ca(OH)2, concentrations (0.0, 0.10, 0.30, 0.50 %, dry basis, d.b.) on the apparent viscosity and maximum gelatinization temperature of a cornstarch water slurry was assessed. This Mexican traditional thermal‐alkaline gelatinization reaction (TAGR) was evaluated in a Brabender Viscoamylograph. This small well‐mixed reactor was homogeneously heated, and apparent viscosity data from corn starch were recorded in Brabender Units BU). It was found that an increase in Ca(OH)2 concentrations considerably increases the apparent viscosity, thus reducing the time needed to reach the maximum gelatinization temperature. A mathematical model that represents the phenomena, that occur in the Viscoamylograph, was developed. In the model the Viscoamylograph was considered as a batch reactor and the apparent kinetic coefficients for the TAGR were obtained, including mass balances and thermal‐alkaline gelatinization rates, considering a spherical cornstarch granule formed by a starchy matrix. Activation energy found for this reaction was 1241 kJ. 相似文献
100.