全文获取类型
收费全文 | 822篇 |
免费 | 24篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 48篇 |
化学工业 | 137篇 |
金属工艺 | 12篇 |
机械仪表 | 13篇 |
建筑科学 | 8篇 |
能源动力 | 60篇 |
轻工业 | 54篇 |
水利工程 | 2篇 |
无线电 | 111篇 |
一般工业技术 | 117篇 |
冶金工业 | 209篇 |
原子能技术 | 15篇 |
自动化技术 | 63篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 14篇 |
2020年 | 13篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 15篇 |
2014年 | 23篇 |
2013年 | 35篇 |
2012年 | 15篇 |
2011年 | 37篇 |
2010年 | 33篇 |
2009年 | 28篇 |
2008年 | 31篇 |
2007年 | 23篇 |
2006年 | 10篇 |
2005年 | 16篇 |
2004年 | 26篇 |
2003年 | 13篇 |
2002年 | 19篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 27篇 |
1998年 | 59篇 |
1997年 | 53篇 |
1996年 | 41篇 |
1995年 | 19篇 |
1994年 | 25篇 |
1993年 | 24篇 |
1992年 | 21篇 |
1991年 | 14篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 2篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1965年 | 1篇 |
排序方式: 共有849条查询结果,搜索用时 15 毫秒
841.
Michiko Ishihara Harmit Singh Glen Chung Chick Tam 《Journal of the science of food and agriculture》2007,87(15):2844-2852
BACKGROUND: Isoflavones, found in soymilk and tofu, are one of the phytochemicals in soy‐based products that may promote good health. Homemade tofu and various homemade soymilk samples were made using different soaking, grinding, and cooking methods. The homemade samples were compared to commercial tofu and soymilk for total isoflavone content and composition as well as their antioxidant capacity. All samples were freeze‐dried and extracted with a 58% acetonitrile solution which was subsequently used to determine the isoflavone content by reverse‐phase high‐performance liquid chromatography. The antioxidant activity of extracts was determined using a modified 2,2‐azino‐bis‐(3‐ethylbenzthiazoline‐6‐sulfonic acid) method and total antioxidant capacity was reported as ascorbic acid equivalents. RESULTS: The total isoflavone, aglycone, and antioxidant levels were significantly higher in homemade soymilk and tofu (1571 µg) than in commercial samples. Homemade soymilk made by the extended boiling method yielded the highest total isoflavone (2567 µg) and glucoside (1525 µg) content. A strong positive correlation was observed between the total isoflavone, aglycone conjugates, and genistein series concentration and antioxidant capacity of soymilk. CONCLUSION: Increased moist heating time yielded the highest concentration of total isoflavones as well as aglycone conjugates and the genistein series. Increasing the duration of boiling can increase the isoflavone content of both homemade and commercial soymilk and tofu. Copyright © 2007 Society of Chemical Industry 相似文献
842.
Degradation of pectic substances by two pectate lyases from a human intestinal bacterium, Clostridium butyricum-beijerinckii group 总被引:1,自引:0,他引:1
Nakajima N Ishihara K Tanabe M Matsubara K Matsuura Y 《Journal of Bioscience and Bioengineering》1999,88(3):331-333
Clostridium butyricum-beijerinckii group, an anaerobic human intestinal bacterium, produced exo-pectate lyase, endo-pectate lyase, and pectin methylesterase, but not polygalacturonase. The production of the two pectate lyases was strongly influenced by the composition of the carbon sources added to the medium. The enzymes secreted by the bacterium into the human large intestine cooperatively digested pectic substances, producing mainly 4,5-unsaturated digalacturonic acid with the participation of the pectin methylesterase. The findings suggest that in the human intestine the bacterium contributes to the digestion of ingested pectic substances. 相似文献
843.
F. O. Adurodija H. Izumi T. Ishihara H. Yoshioka M. Motoyama 《Solar Energy Materials & Solar Cells》2002,71(1)
The electrical and optical properties of pulsed laser deposited amorphous indium tin oxide films at room temperature are discussed. The films were grown from indium oxide (In2O3) targets of different tin (Sn) doping content (0, 5 and 10 wt%) at different oxygen pressures (PO2) ranging from 1×10−3 to 5×10−2 Torr. The electrical and optical properties of the films were examined by Hall measurements and optical spectrophotometry. It was found that high conductivity amorphous films could be prepared at room temperature irrespective of the Sn doping content. The properties of these films deposited from 0, 5, 10 wt% Sn-doped In2O3 targets show a similar response to changes in PO2. The maximal conductivity of (4.0, 2.1 and 1.8)×103 S/cm and optical transmittance (visible) higher than 90% were obtained at PO2 region of (1–1.5)×10−2 Torr. An undoped In2O3 film produced the highest conductivity of 4×103 S/cm in these studies. 相似文献
844.
A correction factor accounting for the effect of elastic deformation of flange is proposed for the ultimate strength analysis of L‐type flanges used for wind turbine towers. It is derived based on systematic analyses and explicitly expressed as a function of flange dimensions. The proposed factor is simple and suitable for the engineering applications, comparing with the conventional formula for the ultimate strength analysis of flange connections. 相似文献
845.
Taira Matsuo Rie Komori Minami Nakatani Shiori Ochi Aya Yokota-Nakatsuma Junichi Matsumoto Fuyuko Takata Shinya Dohgu Yasuhiro Ishihara Kouichi Itoh 《International journal of molecular sciences》2022,23(14)
Acute brain inflammation after status epilepticus (SE) is involved in blood–brain barrier (BBB) dysfunction and brain edema, which cause the development of post-SE symptomatic epilepsy. Using pilocarpine-induced SE mice, we previously reported that treatment with levetiracetam (LEV) after SE suppresses increased expression levels of proinflammatory mediators during epileptogenesis and prevents the development of spontaneous recurrent seizures. However, it remains unclear how LEV suppresses neuroinflammation after SE. In this study, we demonstrated that LEV suppressed the infiltration of CD11b+CD45high cells into the brain after SE. CD11b+CD45high cells appeared in the hippocampus between 1 and 4 days after SE and contained Ly6G+Ly6C+ and Ly6G−Ly6C+ cells. Ly6G+Ly6C+ cells expressed higher levels of proinflammatory cytokines such as IL-1β and TNFα suggesting that these cells were inflammatory neutrophils. Depletion of peripheral Ly6G+Ly6C+ cells prior to SE by anti-Ly6G antibody (NIMP-R14) treatment completely suppressed the infiltration of Ly6G+Ly6C+ cells into the brain. Proteome analysis revealed the downregulation of a variety of inflammatory cytokines, which exhibited increased expression in the post-SE hippocampus. These results suggest that Ly6G+Ly6C+ neutrophils are involved in the induction of acute brain inflammation after SE. The proteome expression profile of the hippocampus treated with LEV after SE was similar to that after NIMP-R14 treatment. Therefore, LEV may prevent acute brain inflammation after SE by suppressing inflammatory neutrophil infiltration. 相似文献
846.
Y Kawanishi S Ishihara T Tsushima S Hagishita M Ishikawa Y Ishihara 《Canadian Metallurgical Quarterly》1997,5(7):1401-1409
In order to study structure-activity relationships of the previously reported dual histamine H2 and gastrin receptor antagonists and also to improve their low oral absorbability, we tried two chemical modifications. One tried to decrease the high hydrophobicity of the parent hybrid compounds to an appropriate level by incorporating a hydrophilic group into the molecule and the other by replacing the more hydrophobic groups with less hydrophobic ones. The former compounds (type I) involved hybrid compounds with a hydroxyl group at a position of a spacer, a piperidine moiety of H2A, or a phenyl ring at the C5 of the benzodiazepine skeleton as well as those with a free carboxyl group in the piperidine moiety of H2A. The latter (type II) involved hybrid compounds with the C5-phenyl group replaced with either a methyl group or hydrogen atom. Among them, only a type I compound, ([2-[3-(3-piperidin-1-ylmethylphenoxy)propylcarbamoyl] ethylcarbamoyl]methyl)carbamic acid 3-[3-[5-(3-hydroxyphenyl)-1-methyl-2-oxo-2,3-dihydro-1H-1,4-benzodiaz epin-3-yl]ureido]benzyl ester (18), showed potent dual histamine H2 and gastrin receptor antagonistic activity, whereas others resulted in a significant decrease of histamine H2 receptor antagonistic activity. The in vivo gastric acid antisecretory activity of 18 evaluated by Schild's rat method, however, did not suggest any notable improvement in oral absorbability. 相似文献
847.
Aleksandar Staykov Helena Tellez John Druce Ji Wu Tatsumi Ishihara John Kilner 《Science and Technology of Advanced Materials》2018,19(1):221-230
Surface reactivity and near-surface electronic properties of SrO-terminated SrTiO3 and iron doped SrTiO3 were studied with first principle methods. We have investigated the density of states (DOS) of bulk SrTiO3 and compared it to DOS of iron-doped SrTiO3 with different oxidation states of iron corresponding to varying oxygen vacancy content within the bulk material. The obtained bulk DOS was compared to near-surface DOS, i.e. surface states, for both SrO-terminated surface of SrTiO3 and iron-doped SrTiO3. Electron density plots and electron density distribution through the entire slab models were investigated in order to understand the origin of surface electrons that can participate in oxygen reduction reaction. Furthermore, we have compared oxygen reduction reactions at elevated temperatures for SrO surfaces with and without oxygen vacancies. Our calculations demonstrate that the conduction band, which is formed mainly by the d-states of Ti, and Fe-induced states within the band gap of SrTiO3, are accessible only on TiO2 terminated SrTiO3 surface while the SrO-terminated surface introduces a tunneling barrier for the electrons populating the conductance band. First principle molecular dynamics demonstrated that at elevated temperatures the surface oxygen vacancies are essential for the oxygen reduction reaction. 相似文献
848.
Ni‐Fe Nitride Nanoplates on Nitrogen‐Doped Graphene as a Synergistic Catalyst for Reversible Oxygen Evolution Reaction and Rechargeable Zn‐Air Battery
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yuchi Fan Shintaro Ida Aleksandar Staykov Taner Akbay Hidehisa Hagiwara Junko Matsuda Kenji Kaneko Tatsumi Ishihara 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(25)
Obtaining bifunctional electrocatalysts with high activity for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is a main hurdle in the application of rechargeable metal‐air batteries. Earth‐abundant 3d transition metal‐based catalysts have been developed for the OER and ORR; however, most of these are based on oxides, whose insulating nature strongly restricts their catalytic performance. This study describes a metallic Ni‐Fe nitride/nitrogen‐doped graphene hybrid in which 2D Ni‐Fe nitride nanoplates are strongly coupled with the graphene support. Electronic structure of the Ni‐Fe nitride is changed by hybridizing with the nitrogen‐doped graphene. The unique heterostructure of this hybrid catalyst results in very high OER activity with the lowest onset overpotential (150 mV) reported, and good ORR activity comparable to that for commercial Pt/C. The high activity and durability of this bifunctional catalyst are also confirmed in rechargeable zinc‐air batteries that are stable for 180 cycles with an overall overpotential of only 0.77 V at 10 mA?2. 相似文献
849.
Shusei Kawara Brian Cunningham James Bezer Neelima KC Jingwen Zhu Meng-Xing Tang Jun Ishihara James J. Choi Sam H. Au 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(42):2301163
Microvascular networks are essential for the efficient transport of nutrients, waste products, and drugs throughout the body. Wire-templating is an accessible method for generating laboratory models of these blood vessel networks, but it has difficulty fabricating microchannels with diameters of ten microns and narrower, a requirement for modeling human capillaries. This study describes a suite of surface modification techniques to selectively control the interactions amongst wires, hydrogels, and world-to-chip interfaces. This wire templating method enables the fabrication of perfusable hydrogel-based rounded cross-section capillary-scale networks whose diameters controllably narrow at bifurcations down to 6.1 ± 0.3 microns in diameter. Due to its low cost, accessibility, and compatibility with a wide range of common hydrogels of tunable stiffnesses such as collagen, this technique may increase the fidelity of experimental models of capillary networks for the study of human health and disease. 相似文献