全文获取类型
收费全文 | 766篇 |
免费 | 26篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 241篇 |
金属工艺 | 22篇 |
机械仪表 | 13篇 |
建筑科学 | 14篇 |
能源动力 | 15篇 |
轻工业 | 98篇 |
水利工程 | 7篇 |
石油天然气 | 2篇 |
无线电 | 60篇 |
一般工业技术 | 106篇 |
冶金工业 | 142篇 |
原子能技术 | 12篇 |
自动化技术 | 51篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 16篇 |
2021年 | 20篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 19篇 |
2015年 | 14篇 |
2014年 | 24篇 |
2013年 | 31篇 |
2012年 | 36篇 |
2011年 | 45篇 |
2010年 | 35篇 |
2009年 | 29篇 |
2008年 | 35篇 |
2007年 | 30篇 |
2006年 | 29篇 |
2005年 | 25篇 |
2004年 | 22篇 |
2003年 | 18篇 |
2002年 | 21篇 |
2001年 | 11篇 |
2000年 | 16篇 |
1999年 | 14篇 |
1998年 | 65篇 |
1997年 | 44篇 |
1996年 | 27篇 |
1995年 | 19篇 |
1994年 | 18篇 |
1993年 | 11篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 8篇 |
1972年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有795条查询结果,搜索用时 15 毫秒
61.
Noriko Saruta Toshiro Fukami Takayuki Furuishi Toyofumi Suzuki Kazuo Tomono 《Advanced Powder Technology》2010,21(3):326-330
Teprenone (Tp) is a widely used pharmaceutically active ingredient in terpene anti-ulcer agents. We investigated Tp and cyclodextrin (CD) complexes for the objective of forming stable Tp powders. Tp was combined with each CD at a molar ratio of 1:2, kneaded together while adding an appropriate amount of water, then dried under reduced pressure and lightly milled into a powder to produce a kneaded mixture (KM). Powder X-ray diffraction of KM containing Tp and β- and γ-CD revealed new diffraction peaks. On infrared spectroscopy, the peak near 1718 cm?1 corresponding to the carbonyl group of Tp had shifted to around 1701 cm?1. Solid-state NMR spectroscopy showed signs of inhibited molecular mobility of Tp, which is liquid at room temperature, confirming that Tp had formed complexes with β- and γ-CD. Photostability analysis of Tp showed improved stability in the order of γ-CD > β-CD ? α-CD. 相似文献
62.
Kazuki Kai Masafumi Moriyama A. S. M. Rafiul Haque Taichi Hattori Akira Chinju Chen Hu Keigo Kubota Yuka Miyahara Noriko Kakizoe-Ishiguro Shintaro Kawano Seiji Nakamura 《International journal of molecular sciences》2021,22(17)
Tumor-associated macrophages (TAMs) promote cancer cell proliferation and metastasis, as well as anti-tumor immune suppression. Recent studies have shown that tumors enhance the recruitment and differentiation of TAMs, but the detailed mechanisms have not been clarified. We thus examined the influence of cancer cells on the differentiation of monocytes to TAM subsets, including CD163+, CD204+, and CD206+ cells, in oral squamous cell carcinoma (OSCC) using immunohistochemistry, flow cytometry, and a cytokine array. Furthermore, we investigated the effect of OSCC cells (HSC-2, SQUU-A, and SQUU-B cells) on the differentiation of purified CD14+ cells to TAM subsets. The localization patterns of CD163+, CD204+, and CD206+ in OSCC sections were quite different. The expression of CD206 on CD14+ cells was significantly increased after the co-culture with OSCC cell lines, while the expressions of CD163 and CD204 on CD14+ cells showed no change. High concentrations of plasminogen activator inhibitor-1 (PAI-1) and interleukin-8 (IL-8) were detected in the conditioned medium of OSCC cell lines. PAI-1 and IL-8 stimulated CD14+ cells to express CD206. Moreover, there were positive correlations among the numbers of CD206+, PAI-1+, and IL-8+ cells in OSCC sections. These results suggest that PAI-1 and IL-8 produced by OSCC contribute to the differentiation of monocytes to CD206+ TAMs. 相似文献
63.
Yuichiro Hirota Yohei Maeda Norikazu Nishiyama Takashi Furusawa Akira Ito 《American Institute of Chemical Engineers》2016,62(3):624-628
Ionic liquid/polyvinylidene fluoride composite membrane was successfully prepared by impregnation method and used for the separation on organic chemical hydride process. The separation factors of C6H6/H2 and C6H12/H2 in the ternary mixture system were 7500 and 300, respectively. The ionic liquid membrane showed an excellent possibility as a technology of H2 purification in the organic chemical hydride process by removing aromatic hydrocarbon and cycloalkane simultaneously from the ternary system. © 2015 American Institute of Chemical Engineers AIChE J, 62: 624–628, 2016 相似文献
64.
Miyagawa Y Sato H Okabe T Nishiyama T Miyajima M Sunada H 《Drug development and industrial pharmacy》1999,25(4):429-435
The in vivo performance of wax matrix granules (WMGs) prepared by a twin-screw compounding extruder was evaluated in fasted beagle dogs. In vitro dissolution behavior of the model drug, diclofenac sodium (DS), from WMGs was strongly influenced by pH in a dissolution medium due to its solubility (DS is soluble in pH 6.8 and insoluble in pH 1.2 and 4.0) and was independent of paddle rotation rate (50, 100, and 200 rpm) of the dissolution apparatus. Pharmacokinetics parameters such as mean residence time (MRT) showed a sustained action of WMGs in beagle dogs; however, the transit time of WMGs in the small intestine is found to control total drug absorption. Furthermore, the values of the area under the curve (AUC) of the plasma concentration-time curve and the maximum concentration Cmax significantly decreased with decreases in hydroxypropylcellulose (HPC) content in WMGs. Good correlation between one in vitro dissolution parameter (mean dissolution time, MDT) and two in vivo parameters (AUC12 and MRT) suggested that it would be possible to design WMGs with a desired in vivo performance by controlling HPC content. 相似文献
65.
Hiroyasu Hotokezaka Noboru Aoyagi Yasuhiro Kawahara Noriko U. Yamaguchi Shinya Nagasaki Ken Sasaki Satoru Tanaka 《Microsystem Technologies》2005,11(8-10):974-979
Laser-induced breakdown spectroscopy (LIBS) has been applied for quantitative analysis of Al2O3, CaCO3 and MgO particles suspended in water. In the single elemental system, the plasma emission intensities of Al, Ca and Mg were linearly increased with concentration of elements in the range of 1.0×10?5–1.0×10?3 M, 1.0×10?4–2.0×10?3 M and 8.0×10?5 –4.0×10?3 M, respectively. We also investigated the concentration dependence of breakdown spectra for suspended mixtures of Al2O3, CaCO3 and MgO particles. The emission lines, such as Al I, Ca I, Ca II and Mg I, were appeared in the LIBS spectrum simultaneously, and each emission peak could be deconvoluted. The plasma emission intensities of Al, Ca and Mg in the multielemental system were also linearly increased with their concentrations in the range of 1.0×10?5–1.0×10?3 M, 1.0×10?4–2.0×10?3 M and 4.0×10?4–2.0×10?3 M, respectively. LIBS was found to be available for quantitative and qualitative measurement of the concentrations of Al2O3, CaCO3 and MgO particles suspended in water. The present results suggest that LIBS is a potentially useful tool for in-situ analysis on particles composition and concentrations for environmental monitoring by the wearable information equipments. 相似文献
66.
In this paper we propose a new software development process simulation model. The model can predict variations of productivity based on dynamic changes in the developer's knowledge structure. An important concept of the model is that a developer's productivity is influenced by the developer's knowledge. Moreover, a developer can acquire new knowledge by executing activities of a project. In other words, the developer's knowledge structure changes during the project. The knowledge structure is defined using a cognitive map that consists of knowledge elements and prerequisite relationships among the knowledge elements. By adding the specific developer's knowledge and the specific project workload to the knowledge structure, an increment of the developer's knowledge and the project progress are calculated into the model. The simulation results are useful for making project plans including technical reviews, which are an efficient technique for acquiring new knowledge. The simulation model can predict what knowledge should be discussed in the technical review, when the review should be held, and who the members of the review should be. The simulation results help managers make the most appropriate and executable project plan. 相似文献
67.
Artificial Life and Robotics - In recent years, unspecified messages posted on social media have significantly affected the price fluctuations of online-traded products, such as stocks and virtual... 相似文献
68.
Yuanbo Liu Soichi Nishiyama Tomohisa Yano 《International journal of remote sensing》2013,34(11):2121-2139
Although change detection algorithms for temporal remote sensing images have been compared using various datasets, there is no general agreement on their performance for separating change and no-change. This study compared image differencing, image ratioing, image regression, and principal component analysis (PCA) from a mathematical perspective. Error analysis showed that no-change pixels with errors are expected to be located within an error zone in bi-temporal space. Bi-temporal space consists of two temporal axes of target pixel values observed successively. All algorithms confine a no-change area to a zone delineating change and no-change pixels in the space. Image ratioing defines a fan-like sector as a no-change area, generally unsuitable for change detection. The other algorithms confine a no-change area to a strip-like zone. Image differencing defines a no-change zone with a fixed slope, leading to its inability to specify flexibly the error zone that varies with different conditions. In the examined case, image regression and standardized PCA (SPCA) achieved the best performance for change detection, followed by PCA, image differencing, and image ratioing. 相似文献
69.
70.
This note examines testing methods for Paretoness in the framework of rank-size rule regression. Rank-size rule regression describes a relationship found in the analysis of various topics such as city population, words in texts, scale of companies and so on. In terms of city population, it is basically an empirical rule that log?(S(i)) is approximately a linear function of log?(i) where S(i) is the number of population of i th largest city in a country. This is closely related to the so-called Zipf’s law. It is known that this kind of empirical observation is found when the city population is a random variable following a Pareto distribution. Thus one may be willing to test if city size has a Pareto distribution or not. Rosen and Resnick [K.T. Rosen, M. Resnick, The size distribution of cities: an explanation of the Pareto law and primacy, Journal of Urban Economics 8 (1980), 165–186] and Soo [K.T. Soo, Zipf’s law for cities: a cross country investigation, Regional Science and Urban Economics (35) 2005, 239–263] regress log?(S(i)) on log?(i) and log?2(i) and test the null of Paretoness by standard t-test for the latter regressor. It is found that t-statistics take large values and the Paretoness is rejected in many countries. We study the statistical properties of the t-statistic and show that it explodes asymptotically, in fact, by simulation and thus the t-test does not provide a reasonable testing procedure. We propose an alternative test statistic which seems to be asymptotically normally distributed. We also propose a test with the null hypothesis that the city size distribution is Pareto with exponent unity, which is a modification of the F-test. 相似文献