全文获取类型
收费全文 | 2752篇 |
免费 | 76篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 101篇 |
综合类 | 2篇 |
化学工业 | 579篇 |
金属工艺 | 100篇 |
机械仪表 | 32篇 |
建筑科学 | 32篇 |
矿业工程 | 1篇 |
能源动力 | 109篇 |
轻工业 | 190篇 |
水利工程 | 7篇 |
石油天然气 | 4篇 |
无线电 | 226篇 |
一般工业技术 | 438篇 |
冶金工业 | 698篇 |
原子能技术 | 63篇 |
自动化技术 | 253篇 |
出版年
2024年 | 5篇 |
2023年 | 28篇 |
2022年 | 44篇 |
2021年 | 56篇 |
2020年 | 34篇 |
2019年 | 34篇 |
2018年 | 53篇 |
2017年 | 49篇 |
2016年 | 79篇 |
2015年 | 35篇 |
2014年 | 72篇 |
2013年 | 103篇 |
2012年 | 116篇 |
2011年 | 121篇 |
2010年 | 92篇 |
2009年 | 108篇 |
2008年 | 103篇 |
2007年 | 98篇 |
2006年 | 93篇 |
2005年 | 85篇 |
2004年 | 67篇 |
2003年 | 82篇 |
2002年 | 51篇 |
2001年 | 46篇 |
2000年 | 39篇 |
1999年 | 60篇 |
1998年 | 285篇 |
1997年 | 145篇 |
1996年 | 91篇 |
1995年 | 60篇 |
1994年 | 68篇 |
1993年 | 71篇 |
1992年 | 52篇 |
1991年 | 25篇 |
1990年 | 25篇 |
1989年 | 27篇 |
1988年 | 19篇 |
1987年 | 21篇 |
1986年 | 10篇 |
1985年 | 25篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1982年 | 20篇 |
1981年 | 19篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 14篇 |
1976年 | 29篇 |
1973年 | 4篇 |
排序方式: 共有2835条查询结果,搜索用时 0 毫秒
51.
Fatigue tests were conducted for 1800 MPa-class spring steels at various stress ratios. For comparison, similar fatigue tests were conducted for conventional steels whose tensile strength was lower than 1200 MPa. The spring steels exhibited fish-eye fractures, and the origins of these fractures were oxide, TiN and the matrix itself. In contrast, the conventional steels never exhibited fish-eye fractures. The fatigue strength of these steels decreased monotonously as the stress ratio increased, when the fatigue strength was evaluated in terms of stress amplitude. However, the fatigue strength degradation was less than that expected from a modified-Goodman line, and the best fit line was obtained by connecting the fatigue limit at zero mean stress to true fracture strength instead of tensile strength. This research also reviewed application of a power low to the stress ratio effect evaluation. In these results, the difference between the spring and conventional steels was negligible. 相似文献
52.
Out‐of‐Plane Strain Induced in a Moiré Superstructure of Monolayer MoS2 and MoSe2 on Au(111) 下载免费PDF全文
Satoshi Yasuda Ryosuke Takahashi Ryo Osaka Ryota Kumagai Yasumitsu Miyata Susumu Okada Yuhei Hayamizu Kei Murakoshi 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(31)
Making contact of transition metal dichalcogenides (TMDCs) with a metal surface is essential for fabricating and designing electronic devices and catalytic systems. It also generates strain in the TMDCs that plays significant role in both electronic and phonon structures. Therefore, detailed understanding of mechanism of the strain generation is important to fully comprehend the modulation effect for the electronic and phonon properties. Here, MoS2 and MoSe2 monolayers are grown on Au surface by chemical vapor deposition and it is demonstrated that the contact with a crystalline Au(111) surface gives rise to only out‐of‐plane strain in both MoS2 and MoSe2 layers, whereas no strain generation is observed on polycrystalline Au or SiO2/Si surfaces. Scanning tunneling microscopy analysis provides information regarding consequent specific adsorption sites between lower S (Se) atoms in the S? Mo? S (Se? Mo? Se) structure and Au atoms via unique moiré superstructure formation for MoS2 and MoSe2 layers on Au(111). This observation indicates that the specific adsorption sites give rise to out‐of‐plane strain in the TMDC layers. Furthermore, it also leads to effective modulation of the electronic structure of the MoS2 or MoSe2 layer. 相似文献
53.
Minami Yamauchi Toshihiro Sato Ayana Otake Masaki Kumondai Yu Sato Masafumi Kikuchi Masamitsu Maekawa Hiroaki Yamaguchi Takaaki Abe Nariyasu Mano 《International journal of molecular sciences》2022,23(15)
Patients with liver diseases not only experience the adverse effects of liver-metabolized drugs, but also the unexpected adverse effects of renally excreted drugs. Bile acids alter the expression of renal drug transporters, however, the direct effects of bile acids on drug transport remain unknown. Renal drug transporter organic anion-transporting polypeptide 4C1 (OATP4C1) was reported to be inhibited by chenodeoxycholic acid. Therefore, we predicted that the inhibition of OATP4C1-mediated transport by bile acids might be a potential mechanism for the altered pharmacokinetics of renally excreted drugs. We screened 45 types of bile acids and calculated the IC50, Ki values, and bile acid–drug interaction (BDI) indices of bile acids whose inhibitory effect on OATP4C1 was >50%. From the screening results, lithocholic acid (LCA), glycine-conjugated lithocholic acid (GLCA), and taurine-conjugated lithocholic acid (TLCA) were newly identified as inhibitors of OATP4C1. Since the BDI index of LCA was 0.278, LCA is likely to inhibit OATP4C1-mediated transport in clinical settings. Our findings suggest that dose adjustment of renally excreted drugs may be required in patients with renal failure as well as in patients with hepatic failure. We believe that our findings provide essential information for drug development and safe drug treatment in clinics. 相似文献
54.
55.
Johann Kalchman Shingo Fujioka Seok Chung Yamato Kikkawa Toshihiro Mitaka Roger D. Kamm Kazuo Tanishita Ryo Sudo 《Microfluidics and nanofluidics》2013,14(6):969-981
Most anti-cancer drug screening assays are currently performed in two dimensions, on flat, rigid surfaces. However, there are increasing indications that three-dimensional (3D) platforms provide a more realistic setting to investigate accurate morphology, growth, and sensitivity of tumor cells to chemical factors. Moreover, interstitial flow plays a pivotal role in tumor growth. Here, we present a microfluidic 3D platform to investigate behaviors of tumor cells in flow conditions with anti-migratory compounds. Our results show that interstitial flow and its direction have significant impact on migration and growth of hepatocellular carcinoma cell lines such as HepG2 and HLE. In particular, HepG2/HLE cells tend to migrate against interstitial flow, and their growth increases in interstitial flow conditions regardless of the flow direction. Furthermore, this migratory activity of HepG2 cells is enhanced when they are co-cultured with human umbilical vein endothelial cells. We also found that migration activity of HepG2 cells attenuates under hypoxic conditions. In addition, the effect of Artemisinin, an anti-migratory compound, on HepG2 cells was quantitatively analyzed. The microfluidic 3D platform described here is useful to investigate more accurately the effect of anti-migratory drugs on tumor cells and the critical influence of interstitial flow than 2D culture models. 相似文献
56.
Yasuyoshi Kaneko Shinya Matsushita Yasufumi Oikawa Shigeru Abe 《Electrical Engineering in Japan》2010,172(2):47-54
The equivalent circuit, the efficiency, and the important characteristics of moving pick‐up type contactless power transfer systems are described. If the primary series capacitor and the secondary parallel capacitors are chosen correctly and the winding resistances are ignored, the equivalent circuit of the transformer with these capacitors becomes the same as an ideal transformer at the resonant frequency. This simple approximation helps to understand the phenomena occurring with load changes. Because the circuit analysis becomes simple, the approximate value of the power transfer efficiency can be derived. This paper describes the determination of the capacitor values, the derivation of the equivalent circuit and the efficiency, and test results. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(2): 47–54, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20970 相似文献
57.
Sumikin Iron and Steel Corporation (SISC) is the main manufacturing base of seamless tube materials in Sumitomo Metals group, and stainless steel making plant is in charge of semi‐manufactured special steel products such as stainless and high alloy steel. Total manufacturing costs of these special steels are heavily dependent on the price of raw material. Therefore, reduction of its usage and optimizing operation process in order to absorb influence of its unstable price are important issues. In this report, we introduce three cases as following: yield improvement in order to reduce raw material usage, optimization of the steel dust usage, and active use of low‐price raw material through dividing refining process. 相似文献
58.
Hirobumi Shibata Tomoaki Morita Taku Ogura Keishi Nishio Hideki Sakai Masahiko Abe Mutsuyoshi Matsumoto 《Journal of Materials Science》2009,44(10):2541-2547
Mesostructured zirconia particles having monoclinic-type crystalline walls were prepared using a low-temperature crystallization
technique. Crystalline zirconia particles with highly-ordered mesostructures were obtained through the sol–gel process of
zirconium sulfate tetrahydrate at 333 K in the presence of molecular self-assemblies of cetyltrimethylammonium bromide (CTAB)
or mixtures of CTAB and anionic molecules such as sodium dodecyl sulfate and sodium p-toluenesulfonate. Variations in the molar ratios of CTAB and the chemical species of anionic molecules led to the variations
in the periods of highly-ordered zirconia having crystalline walls. Calcination of the mesostructured zirconia particles prepared
using templates consisting solely of CTAB yielded crystalline mesoporous zirconia particles. 相似文献
59.
Many studies have focused on the stabilization of additive manufacturing (AM) in microgravity for its use in various space projects. Nevertheless, this paper presents a vital clue for innovating metal AM technologies from the perspective of high gravity. High-gravitational powder bed fusion has an excellent potential to address various challenges in AM, such as density enhancement, spatter suppression, and precise fabrication. This study summarizes an analogy among phenomena in different gravitational fields and establishes a combined machine for centrifuge and powder bed fusion. The results confirm the spatter suppression and fine-powder availability in high gravity, both theoretically and experimentally. 相似文献
60.