全文获取类型
收费全文 | 2327篇 |
免费 | 44篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 171篇 |
化学工业 | 519篇 |
金属工艺 | 31篇 |
机械仪表 | 57篇 |
建筑科学 | 25篇 |
矿业工程 | 2篇 |
能源动力 | 88篇 |
轻工业 | 208篇 |
水利工程 | 2篇 |
石油天然气 | 5篇 |
无线电 | 230篇 |
一般工业技术 | 327篇 |
冶金工业 | 497篇 |
原子能技术 | 76篇 |
自动化技术 | 137篇 |
出版年
2023年 | 7篇 |
2022年 | 27篇 |
2021年 | 48篇 |
2020年 | 16篇 |
2019年 | 21篇 |
2018年 | 26篇 |
2017年 | 19篇 |
2016年 | 33篇 |
2015年 | 38篇 |
2014年 | 44篇 |
2013年 | 136篇 |
2012年 | 77篇 |
2011年 | 102篇 |
2010年 | 73篇 |
2009年 | 100篇 |
2008年 | 102篇 |
2007年 | 86篇 |
2006年 | 71篇 |
2005年 | 62篇 |
2004年 | 56篇 |
2003年 | 77篇 |
2002年 | 62篇 |
2001年 | 50篇 |
2000年 | 37篇 |
1999年 | 60篇 |
1998年 | 196篇 |
1997年 | 126篇 |
1996年 | 97篇 |
1995年 | 70篇 |
1994年 | 46篇 |
1993年 | 58篇 |
1992年 | 24篇 |
1991年 | 8篇 |
1990年 | 18篇 |
1989年 | 32篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 24篇 |
1985年 | 21篇 |
1984年 | 18篇 |
1983年 | 22篇 |
1982年 | 12篇 |
1981年 | 17篇 |
1980年 | 17篇 |
1978年 | 14篇 |
1977年 | 22篇 |
1976年 | 27篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1972年 | 5篇 |
排序方式: 共有2375条查询结果,搜索用时 0 毫秒
11.
12.
Shoji Seki Mami Iwasaki Hiroto Makino Yasuhito Yahara Miho Kondo Katsuhiko Kamei Hayato Futakawa Makiko Nogami Kenta Watanabe Nguyen Tran Canh Tung Tatsuro Hirokawa Mamiko Tsuji Yoshiharu Kawaguchi 《International journal of molecular sciences》2022,23(9)
The role of the ligamentum flavum (LF) in the pathogenesis of adolescent idiopathic scoliosis (AIS) is not well understood. Using magnetic resonance imaging (MRI), we investigated the degrees of LF hypertrophy in 18 patients without scoliosis and on the convex and concave sides of the apex of the curvature in 22 patients with AIS. Next, gene expression was compared among neutral vertebral LF and LF on the convex and concave sides of the apex of the curvature in patients with AIS. Histological and microarray analyses of the LF were compared among neutral vertebrae (control) and the LF on the apex of the curvatures. The mean area of LF in the without scoliosis, apical concave, and convex with scoliosis groups was 10.5, 13.5, and 20.3 mm2, respectively. There were significant differences among the three groups (p < 0.05). Histological analysis showed that the ratio of fibers (Collagen/Elastic) was significantly increased on the convex side compared to the concave side (p < 0.05). Microarray analysis showed that ERC2 and MAFB showed significantly increased gene expression on the convex side compared with those of the concave side and the neutral vertebral LF cells. These genes were significantly associated with increased expression of collagen by LF cells (p < 0.05). LF hypertrophy was identified in scoliosis patients, and the convex side was significantly more hypertrophic than that of the concave side. ERC2 and MAFB genes were associated with LF hypertrophy in patients with AIS. These phenomena are likely to be associated with the progression of scoliosis. 相似文献
13.
Seiichiro Katagiri SungGi Chi Yosuke Minami Kentaro Fukushima Hirohiko Shibayama Naoko Hosono Takahiro Yamauchi Takanobu Morishita Takeshi Kondo Masamitsu Yanada Kazuhito Yamamoto Junya Kuroda Kensuke Usuki Daigo Akahane Akihiko Gotoh 《International journal of molecular sciences》2022,23(9)
KIT is a type-III receptor tyrosine kinase that contributes to cell signaling in various cells. Since KIT is activated by overexpression or mutation and plays an important role in the development of some cancers, such as gastrointestinal stromal tumors and mast cell disease, molecular therapies targeting KIT mutations are being developed. In acute myeloid leukemia (AML), genome profiling via next-generation sequencing has shown that several genes that are mutated in patients with AML impact patients’ prognosis. Moreover, it was suggested that precision-medicine-based treatment using genomic data will improve treatment outcomes for AML patients. This paper presents (1) previous studies regarding the role of KIT mutations in AML, (2) the data in AML with KIT mutations from the HM-SCREEN-Japan-01 study, a genome profiling study for patients newly diagnosed with AML who are unsuitable for the standard first-line treatment (unfit) or have relapsed/refractory AML, and (3) new therapies targeting KIT mutations, such as tyrosine kinase inhibitors and heat shock protein 90 inhibitors. In this era when genome profiling via next-generation sequencing is becoming more common, KIT mutations are attractive novel molecular targets in AML. 相似文献
14.
Riku Kawasaki Kosuke Kondo Risako Miura Keita Yamana Hinata Isozaki Risako Shimada Shogo Kawamura Hidetoshi Hirano Tomoki Nishimura Naoki Tarutani Kiyofumi Katagiri Alexandra Stubelius Shin-ichi Sawada Yoshihiro Sasaki Kazunari Akiyoshi Atsushi Ikeda 《International journal of molecular sciences》2022,23(9)
Developing photoactivatable theranostic platforms with integrated functionalities of biocompatibility, targeting, imaging contrast, and therapy is a promising approach for cancer diagnosis and therapy. Here, we report a theranostic agent based on a hybrid nanoparticle comprising fullerene nanocrystals and gold nanoparticles (FGNPs) for photoacoustic imaging and photothermal therapy. Compared to gold nanoparticles and fullerene crystals, FGNPs exhibited stronger photoacoustic signals and photothermal heating characteristics by irradiating light with an optimal wavelength. Our studies demonstrated that FGNPs could kill cancer cells due to their photothermal heating characteristics in vitro. Moreover, FGNPs that are accumulated in tumor tissue via the enhanced permeation and retention effect can visualize tumor tissue due to their photoacoustic signal in tumor xenograft model mice. The theranostic agent with FGNPs shows promise for cancer therapy. 相似文献
15.
In this paper we establish the exact solution for a hollow sphere with a rigid-plastic pressure-sensitive matrix and subjected to hydrostatic tension or compression. The matrix is assumed to obey to a parabolic Mises–Schleicher criterion. The closed-form expressions of the velocity field and of the stress field are provided. These exact solutions, expressed by means of the Lambert W function, allow to assess and discuss existing results. 相似文献
16.
This paper first reviews the earthquakes that occurred since 1995 and then outlines the significant lessons learnt from disasters. The discussion then goes into the induced development of engineering practices that were triggered by those disasters. It is clear that major development occurred in design philosophies, soil improvement, and facilities for research. The last section of this paper addresses the compound effects of earthquakes and rainfall that may make the extent of the disasters worse. 相似文献
17.
Yoshimoto N. Shibata Y. Oku S. Kondo S. Noguchi Y. 《Lightwave Technology, Journal of》1999,17(9):1662-1668
The authors have designed and demonstrated a 2×2 Mach-Zehnder switch in view of polarization independence as well as low propagation loss (α) and absorption change (Δα). To obtain polarization-insensitive refractive index change (Δn), a lattice-matched InGaAlAs-InAlAs multiple quantum-well (MQW) with a large detuning wavelength was used. Moreover, to reduce the insertion loss difference between polarizations, we applied a multimode-interferometer 3-dB coupler and a deep-etched high-mesa waveguide structure. This switch, therefore, can provide polarization-independent operation about both driving voltage and insertion loss, which is indispensable to practical optical switching applications. We also paid attention to Δα suppression when we decided the value of wavelength detuning and the length of the phase shift region. We also investigated the wavelength dependence of the switch. Within 1530-1560 nm, which is the erbium-doped fiber amplifier (EDFA) gain band, polarization independence in the driving voltage and the crosstalk was maintained. This result shows that the switch is also applicable in wavelength division multiplexing (WDM) applications 相似文献
18.
A 4*4 directional coupler switch matrix is developed which uses, for the first time, the quantum confined Stark effect of InGaAlAs/InAlAs multiquantum well structures. The rearrangeable nonblocking 4*4 network with six 2*2 switches is shown to be perfectly functional with switching voltages between 5 and 6 V and crosstalk below -17 dB in all the operation states.<> 相似文献
19.
Tohmori Y. Yoshikuni Y. Ishii H. Kano F. Tamamura T. Kondo Y. 《Electronics letters》1993,29(4):352-354
A broad range tuning of over 100 nm in tunable DBR lasers with superstructure grating (SSG) is reported. The SSG reflectors for 100 nm were designed and patterned by electron beam lithography. 1.55 mu m DBR lasers with SSG reflector operate in a single mode with a tuning range of 83 nm under CW conditions. With inclusion of the multimode operating region, the tuning range becomes as wide as 103 nm.<> 相似文献
20.
Kasaya K. Mitomi O. Naganuma M. Kondo Y. Noguchi Y. 《Photonics Technology Letters, IEEE》1993,5(3):345-347
Low-loss coupling between semiconductor photonic devices and single-mode fibers is achieved using a simple InP/InGaAsP tapered waveguide. The proposed simple structure has a small and nearly square guiding core at its output facet. In this structure, the output field has a non-Gaussian profile, but low-pass filter coupling can be achieved by optimizing the design of the guiding core sizes. The waveguide is composed of a laterally tapered InGaAsP guiding layer and an InP cladding region on an InP substrate, facilitating integration of the waveguide with active devices using conventional processes. The waveguide is shown to have a total insertion loss of 2.6 dB, including a coupling loss of 0.9 dB and large ±2.5-μm misalignment tolerance in lateral and vertical directions with single-mode filters 相似文献