全文获取类型
收费全文 | 1214篇 |
免费 | 42篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 50篇 |
化学工业 | 355篇 |
金属工艺 | 22篇 |
机械仪表 | 23篇 |
建筑科学 | 20篇 |
能源动力 | 68篇 |
轻工业 | 101篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 111篇 |
一般工业技术 | 254篇 |
冶金工业 | 122篇 |
原子能技术 | 39篇 |
自动化技术 | 87篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 40篇 |
2021年 | 41篇 |
2020年 | 19篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 27篇 |
2016年 | 38篇 |
2015年 | 20篇 |
2014年 | 53篇 |
2013年 | 83篇 |
2012年 | 80篇 |
2011年 | 74篇 |
2010年 | 56篇 |
2009年 | 57篇 |
2008年 | 60篇 |
2007年 | 45篇 |
2006年 | 51篇 |
2005年 | 35篇 |
2004年 | 26篇 |
2003年 | 35篇 |
2002年 | 29篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 12篇 |
1998年 | 37篇 |
1997年 | 37篇 |
1996年 | 23篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1977年 | 9篇 |
1976年 | 4篇 |
1974年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有1259条查询结果,搜索用时 171 毫秒
1.
Tomohiro Toigawa Yasuhiro Tsubata Takeshi Kai Takuya Furuta Yuta Kumagai Tatsuro Matsumura 《溶剂提取与离子交换》2021,39(1):74-89
ABSTRACT Absorbed-dose estimation is essential for evaluation of the radiation tolerance of minor-actinide-separation processes. We propose a dose-evaluation method based on radiation permeability, with comparisons of heterogeneous structures seen in the solvent-extraction process, such as emulsions forming in the mixture of the organic and aqueous phases. A demonstration of radiation-energy-transfer simulation is performed with a focus on the minor-actinide-recovery process from high-level liquid waste with the aid of the Monte Carlo radiation-transport code PHITS. The simulation results indicate that the dose absorbed by the extraction solvent from alpha radiation depends upon the emulsion structure, and that from beta and gamma radiation depends upon the mixer-settler-apparatus size. Non-negligible contributions of well-permeable gamma rays were indicated in terms of the plant operation of the minor-actinide-separation process. 相似文献
2.
Kazuaki Katagiri Shinya Honda Sayaka Minami Daiki Kimu Shimpei Yamaguchi Takuya Ehiro 《先进材料力学与结构力学》2020,27(18):1541-1550
Abstract The I-shaped cross-sectional beam of CFRP (CFRP I-beam) is usually manufactured by the continuous protrusion method. Carbon fibers can only be arranged in the longitudinal direction. The CFRP I-beam with arbitrary arrangement of carbon fiber was manufactured with applying the electro-activated deposition molding method. The carbon fiber fabric was immersed in the deposition solution and energized, epoxy resin precipitated around carbon fiber and impregnated. The resin-impregnated fabric was installed to the mold, and the CFRP I-beam was fabricated. The CFRP I-beam was subjected to three-point bending tests, and the relationship between load-deflection was simulated by finite-element analysis. 相似文献
3.
Tanabe A. Nakahara Y. Furukawa A. Mogami T. 《Solid-State Circuits, IEEE Journal of》2003,38(1):107-113
A redundant multivalued logic is proposed for high-speed communication ICs. In this logic, serial binary data are received and converted into parallel redundant multivalued data. Then they are restored into parallel binary data. Because of the multivalued data conversion, this logic makes it possible to achieve higher operating speeds than that of a conventional binary logic. Using this logic, a 1:4 demultiplexer (DEMUX, serial-parallel converter) IC was fabricated using a 0.18-/spl mu/m CMOS process. The IC achieved an operating speed of 10 Gb/s with a supply voltage of only 1.3 V and with power consumption of 38 mW. This logic may achieve CMOS communication ICs with an operating speed several times greater than 10 Gb/s. 相似文献
4.
R. Urata R. Takahashi T. Nakahara K. Takahata H. Suzuki 《Photonics Technology Letters, IEEE》2006,18(1):67-69
We propose an optically clocked transistor array optoelectronic integrated circuit (OEIC) for both serial-to-parallel and parallel-to-serial conversion (demux/mux), enabling an interface between high-speed asynchronous burst optical labels and CMOS circuitry for optical label swapping. Dual functionality of the OEIC reduces size, power, and cost of the optical label swapper. The capability for greater than 20-Gb/s conversion operation is demonstrated. 相似文献
5.
Although EDTA-dependent pseudothrombocytopenia (EDTA-PTCP) is of practical importance because failure to recognize this clinical entity may result in misdiagnosis and subsequent mismanagement of the patients, the pathophysiological nature of EDTA-PTCP remains unknown. To develop an effective way to evaluate the platelet counts in patients with EDTA-PTCP, we introduced aminoglycosides-supplemented anticoagulating agents. When kanamycin was pre-supplemented with EDTA for anticoagulating blood samples from EDTA-PTCP patients there was no significant change in the platelet counts and the morphology of blood cells after 150 min of incubation at room temperature. Furthermore, when kanamycin was added to EDTA-anticoagulated blood samples from EDTA-PTCP patients within 30 min after blood withdrawal, rapid dissociation of platelets without apparent morphological changes of blood cells was observed, and complete blood cell counts as well as the histogram patterns were almost the same as those examined immediately after blood sampling. The dissociation of aggregated platelets was also detected when other antibiotics were used, although it was associated with some extent of morphological changes of blood cells. These findings indicate that the supplementation of aminoglycosides either before or after blood sampling is a useful method for the diagnosis EDTA-PTCP and for the evaluation of platelet counts in patients with EDTA-PTCP. 相似文献
6.
Microbial sensor for preliminary screening of mutagens utilizing a phage induction test 总被引:1,自引:0,他引:1
For the preliminary screening of mutagens, a novel microbial sensor system was developed utilizing a phage induction test. Escherichia coli lysogenic strain GY5027 and nonlysogenic strain GY5026 were used in this study. The number of living cells was determined by measuring the respiration of cells immobilized onto an oxygen electrode. The injection of a mutagen, such as AF-2 and MNNG, caused the phage induction in the lysogenic strain, resulting in the decreased respiration of only the lysogenic strain immobilized onto the oxygen electrode but not of nonlysogenic strain. The rate of current increase correlated well with the concentration of mutagens. The sensor responses to the antibiotics and bactericides were definitely different from those of mutagens. Therefore, utilization of this microbial sensor system makes possible the estimation of a substrate's mutagenicity. 相似文献
7.
T Ohnishi T Yano S Nakano S Jinnouchi S Nagamachi LI Flores H Nakahara K Watanabe 《Canadian Metallurgical Quarterly》1997,38(9):1463-1467
We compared the acetazolamide challenge test using 99mTc-ECD SPECT and 123I-IMP SPECT images in patients with chronic occlusive cerebrovascular disease. We also evaluated the usefulness of linearization correction for acetazolamide challenge test of 99mTc-ECD SPECT. METHODS: Twenty patients with unilateral chronic occlusive cerebrovascular disease (10 patients had middle cerebral arterial lesion and 10 had internal carotid lesion) were included in the study. Split-dose (a dose fractioning was 1:2), and sequential SPECT technique was used for 99mTc-ECD SPECT studies while only acetazolamide challenge test studies for 123I-IMP SPECT were performed. Permeability surface area product model (PS model) and back-diffusion model (Lassen's correction) were used for linearization correction of acetazolamide challenge with 99mTc-ECD SPECT. RESULTS: Six of 16 patients with reduced vasodilatory capacity in 123I-IMP SPECT were underestimated by 99mTc-ECD SPECT acetazolamide challenge test. Relative ECD uptake normalized by cerebellar uptake compared with IMP uptake showed a nonlinear relationship, indicating relatively less uptake in high flow range. The underestimations of limited vasodilatory capacity observed in 99mTc-ECD SPECT without linearization correction was modified by linearization algorithm. However, the effect of correction based on PS model was superior than that of Lassen's correction. The corrected 99mTc-ECD uptake ratio, based on PS model, and IMP uptake ratio demonstrated a better linear relationship than that of Lassen's correction. CONCLUSION: Technetium-99m ECD SPECT corrected based on the PS model is a better method of linearization for evaluating cerebrovascular reserve using acetazolamide challenge. 相似文献
8.
The excretion of methoxyphenamine (MOP) and methamphetamine (MA) into beards has been studied. Six healthy male subjects orally took 50 mg of MOP at a single dose and 7 doses for a successive 7 days. Their beard hairs were collected by an electric shaver every morning until MOP disappeared from the beard. After washing with 0.1% SDS, the beard samples were extracted with methanol-5 N HCl (20:1) under ultra-sonication for 1 h and the solution was kept overnight. MOP in the extract was determined by GC/MS using deuterium labelled MOP as an internal standard after trifluoroacetyl-derivatization. The drug concentrations in beard and the reproducibility of analysis were compared with the three procedures, unwashed, 0.1% SDS (wash I) and the additional ethanol (wash II) wash. The drug concentration in beard after SDS wash was 0.5-2.5 ng/mg lower than that in unwashed beard during the first 5-6 days. The drug concentration in beard after ethanol wash was much lower than that in the unwashed beard. The drug excreted into beard was detected 10 approximately 12 days for a single dose and 12-14 days for 7 doses after the last dosage at the cut off level of 1 ng/mg. On the contrary, the drug excreted in urine was not detected after more than 3 days after use. O-Desmethyl MOP, a major metabolite of MOP, was also detected in beard. The procedures were applied to the detection of MA in beard of MA abusers. It was realized that a beard sample was more useful than a urine sample assuming a longer detection. 相似文献
9.
H Kuniyasu W Yasui F Shimamoto K Fujii M Nakahara T Asahara K Dohi E Tahara 《Canadian Metallurgical Quarterly》1996,46(12):1005-1010
A rare case of hepatoblastoma in a 61-year-old Japanese housewife is described. This liver tumor mainly consisted of two tissue components: embryonal hepatocytes and primitive mesenchymal tissue. Fetal hepatocytes with alpha-fetoprotein production, gland formation, cartilage and osteoid were also found in a small portion. Molecular analysis by slot blot method revealed increased copy numbers of c-met and K-sam proto-oncogenes and cyclin D1 genes. These findings suggest that alterations of these oncogenes might play a role in the development of adult hepatoblastoma. 相似文献
10.
With the growing size and complexity of power systems, system analysis—such as transients calculation—takes much time. Hence, fast calculation methods are required. Although parallel processing is a hopeful method, there have been difficulties in the parallel solution of linear equations which appear in power-flow calculations by the Newton-Raphson method. This paper aims at the fast calculation of the power-flow problem by means of parallel processing. In order to improve the suitability to the parallel solution of the differential equation in transients calculation, we assume the use of a direct-mapping parallel processing machine to map directly the network of a power system onto a network of processors. Under this assumption, we propose a new parallel-processing-oriented method in which the linear equation is solved by linear iterations between nodes with Aitken acceleration. We simulate the method on three model power systems and compare this Parallel Iterative Method (PIN) with a Parallel Direct Method (PDM) which uses the banded matrix according to the number of operations required. As a result, we can expect that PIM may solve linear equations faster than PDM with m processors, although the PIM might be inferior to the PDM with m × m processors, where m denotes the half-band width of the banded matrix. 相似文献