全文获取类型
收费全文 | 5083篇 |
免费 | 99篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 220篇 |
综合类 | 5篇 |
化学工业 | 1235篇 |
金属工艺 | 119篇 |
机械仪表 | 114篇 |
建筑科学 | 93篇 |
能源动力 | 207篇 |
轻工业 | 316篇 |
水利工程 | 10篇 |
石油天然气 | 8篇 |
无线电 | 635篇 |
一般工业技术 | 907篇 |
冶金工业 | 965篇 |
原子能技术 | 92篇 |
自动化技术 | 263篇 |
出版年
2023年 | 23篇 |
2022年 | 30篇 |
2021年 | 56篇 |
2020年 | 21篇 |
2019年 | 42篇 |
2018年 | 50篇 |
2017年 | 49篇 |
2016年 | 68篇 |
2015年 | 55篇 |
2014年 | 100篇 |
2013年 | 180篇 |
2012年 | 143篇 |
2011年 | 225篇 |
2010年 | 174篇 |
2009年 | 193篇 |
2008年 | 214篇 |
2007年 | 159篇 |
2006年 | 152篇 |
2005年 | 121篇 |
2004年 | 128篇 |
2003年 | 146篇 |
2002年 | 144篇 |
2001年 | 132篇 |
2000年 | 96篇 |
1999年 | 166篇 |
1998年 | 410篇 |
1997年 | 252篇 |
1996年 | 209篇 |
1995年 | 138篇 |
1994年 | 139篇 |
1993年 | 111篇 |
1992年 | 81篇 |
1991年 | 79篇 |
1990年 | 81篇 |
1989年 | 74篇 |
1988年 | 71篇 |
1987年 | 49篇 |
1986年 | 62篇 |
1985年 | 44篇 |
1984年 | 54篇 |
1983年 | 43篇 |
1982年 | 35篇 |
1981年 | 40篇 |
1980年 | 49篇 |
1979年 | 56篇 |
1978年 | 34篇 |
1977年 | 45篇 |
1976年 | 54篇 |
1973年 | 22篇 |
1972年 | 22篇 |
排序方式: 共有5189条查询结果,搜索用时 15 毫秒
941.
S Morita T Igarashi G Yamada K Suzuki Y Yoshida N Shijubo S Abe 《Canadian Metallurgical Quarterly》1998,36(9):793-797
A 19-year-old woman was admitted to Kushiro city general hospital due to chest pain and dyspnea. Chest radiographs and computed tomographic scan showed a large intrathoracic mass adjacent to the pleura. Angiographs disclosed feeding veins of the tumor arising from lateral thoracic artery. Fine-needle aspiration cytology of the tumor revealed small round cells with a large nuclear/cytoplasmic ratio. Immunocytochemical study demonstrated that the tumor cells were positive for neuron-specific enolase and MIC 2 gene product. The diagnosis was primitive neuroectodermal tumor of the parietal pleura (also known as Askin tumor). Chemotherapy combined with peripheral blood stem cell transplantation reduced the size of the tumor significantly. However, multiple bone metastasis recurred, and the patient died 35 months after the start of therapy. 相似文献
942.
An optical heterodyne interferometer has been combined with a helium flow cryostat to measure the linear thermal expansion coefficient of solids at cryogenic temperatures. The absolute accuracy in length measurement is within a few nanometres. Measurement results on a specimen of fused silica (SRM 739; by US NIST) in the temperature range 6–273 K are presented and compared with some literature data. 相似文献
943.
We report a method that uses near-infrared spectroscopy and multivariate analysis to measure the temperature of turbid aqueous solutions. The measurement principle is based on the fact that the peak wavelength of the water absorption band, with its center near 1440 nm, shifts with changes in temperature. This principle was used to measure the temperatures of 1 mm thick samples of aqueous solutions containing Intralipid (2%), which are often used as optical phantoms for biological tissues due to similar scattering characteristics. Temperatures of pure water and aqueous solutions containing glucose (100 mg/ml and 200 mg/ml) were also measured for comparison. For the turbid Intralipid solutions, the absorbance spectrum varied irregularly with time due to the change in scattering characteristics. However, by making use of the difference between the absorbance at 1412 nm and the temperature-independent absorbance at 1440 nm, we obtained SEPs (standard error of prediction) of 0.3 degrees C and 0.2 degrees C by univariate linear regression and partial least squares regression, respectively. These accuracies were almost the same as those for the transparent samples (pure water and glucose solution). 相似文献
944.
This paper describes an improved microfluidic device that enables hydrodynamic particle concentration and size-dependent separation to be carried out in a continuous manner. In our previous study, a method for hydrodynamic filtration and sorting of particles was proposed using a microchannel having multiple branch points and side channels, and it was applied for continuous concentration and separation of polymer particles and cells. In the current study, the efficiency of particle sorting was dramatically improved by geometrically splitting fluid flow from a main stream and recombining. With these operations, particles with diameters larger than a specific value move toward one sidewall in the mainstream. This control of particle positions is followed by the perfect particle alignment onto the sidewall, which increases the selectivity and recovery rates without using a liquid that does not contain particles. In this study, a microchannel having one inlet and five outlets was designed and fabricated. By simply introducing particle suspension into the device, concentrations of 2.1-3.0-microm particles were increased 60-80-fold, and they were collected independently from each outlet. In addition, it was demonstrated that the measured flow rates distributed into each side channel corresponded well to the theoretical values when regarding the microchannel network as a resistive circuit. 相似文献
945.
Maruo K Oota T Tsurugi M Nakagawa T Arimoto H Hayakawa M Tamura M Ozaki Y Yamada Y 《Applied spectroscopy》2006,60(12):1423-1431
We have applied a new methodology for noninvasive continuous blood glucose monitoring, proposed in our previous paper, to patients in ICU (intensive care unit), where strict controls of blood glucose levels are required. The new methodology can build calibration models essentially from numerical simulation, while the conventional methodology requires pre-experiments such as sugar tolerance tests, which are impossible to perform on ICU patients in most cases. The in vivo experiments in this study consisted of two stages, the first stage conducted on healthy subjects as preliminary experiments, and the second stage on ICU patients. The prediction performance of the first stage was obtained as a correlation coefficient (r) of 0.71 and standard error of prediction (SEP) of 28.7 mg/dL. Of the 323 total data, 71.5% were in the A zone, 28.5% were in the B zone, and none were in the C, D, and E zones for the Clarke error-grid analysis. The prediction performance of the second stage was obtained as an r of 0.97 and SEP of 27.2 mg/dL. Of the 304 total data, 80.3% were in the A zone, 19.7% were in the B zone, and none were in the C, D, and E zones. These prediction results suggest that the new methodology has the potential to realize a noninvasive blood glucose monitoring system using near-infrared spectroscopy (NIRS) in ICUs. Although the total performance of the present monitoring system has not yet reached a satisfactory level as a stand-alone system, it can be developed as a complementary system to the conventional one used in ICUs for routine blood glucose management, which checks the blood glucose levels of patients every few hours. 相似文献
946.
Peening using cavitation impact is called “cavitation shotless peening CSP”, since there is no requirement for shot in the process. Micro- and macro-strain of polycrystalline metal peened by CSP were evaluated using X-ray diffraction methods, as the full width at half maximum (FWHM) of the X-ray diffraction profile from the peened surface was decreased, although compressive residual stress was introduced. It was found that CSP reduced the micro-strain in the surface, but simultaneously introduced compressive residual stress, i.e., a macro-strain. The results demonstrate that the micro-strain is relieved by CSP without the need for heat treatment, and is, therefore, a sort of annealing. Thus, CSP can renew the metallic material while the shape itself is maintained. 相似文献
947.
948.
Michio Yamada Konomi Tokutomi Ayaka Takehara Yusuke Sakai Yutaka Maeda Tadashi Hasegawa 《Fullerenes, Nanotubes and Carbon Nanostructures》2014,22(1-3):66-74
Tröger's base (TB, 1) and its analogues were synthesized and were subject to the titration experiments to evaluate their ability of supramolecular complexation with C60. Results demonstrate clearly that the fluorene-based TB analogue (2) and the bioctylfluorene-based TB analogue (3) show 1:1 binding with C60 to form the corresponding complexes while TB 1 does not. Titration experiments exhibited that the association constant (Kass) of 3/C60 (48.1 ± 7.9 M ?1) was larger than that of 2/C60 (13.7 ± 1.4 M ?1). The formation of the 1:1 binding complexes 2/C60 and 3/C60 was also confirmed by MALDI-TOF mass spectrometry. Theoretical calculations suggest that 2 and 3 have appropriate cavities to embrace C60. These findings indicate that not only the π/π interaction between the fluorene moieties and the C60 surface but also the CH/π interaction between the octyl groups and the C60 surface serve efficiently in the supramolecular complexation with C60. 相似文献
949.
Kazuki Tajima Yasusei Yamada Shanhu Bao Masahisa Okada Kazuki Yoshimura 《Vacuum》2010,84(12):1460-1465
An electrochromic switchable mirror on a flexible plastic sheet was developed taking into consideration practical use, low cost and high adaptability. The mirror has a multilayer of Mg4Ni/Pd/Al/Ta2O5/WO3, which was fabricated by DC magnetron sputtering on an ITO-coated PET sheet. In the previous research, when the mirror was exposed to air for a long period of time, its optical switching properties disappeared. This work focused on the mechanism of degradation of the mirror in different environments. When the mirror was stored in a desiccator for 50 days as a means of preservation, its switching speed was seven times higher as compared with the mirror exposed to air. It is also well known that oxygen and moisture in air easily penetrate PET sheets. The features of the PET sheet strongly affected the durability of the optical switching layer. When the state of the optical switching layer was changed to nonmetallic due to the formation of oxide and hydroxide, the optical switching properties almost disappeared. 相似文献