全文获取类型
收费全文 | 781篇 |
免费 | 11篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 18篇 |
综合类 | 4篇 |
化学工业 | 149篇 |
金属工艺 | 5篇 |
机械仪表 | 16篇 |
建筑科学 | 10篇 |
能源动力 | 7篇 |
轻工业 | 77篇 |
水利工程 | 7篇 |
无线电 | 103篇 |
一般工业技术 | 144篇 |
冶金工业 | 191篇 |
原子能技术 | 34篇 |
自动化技术 | 33篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 15篇 |
2013年 | 30篇 |
2012年 | 22篇 |
2011年 | 26篇 |
2010年 | 15篇 |
2009年 | 24篇 |
2008年 | 35篇 |
2007年 | 28篇 |
2006年 | 28篇 |
2005年 | 16篇 |
2004年 | 21篇 |
2003年 | 19篇 |
2002年 | 15篇 |
2001年 | 24篇 |
2000年 | 12篇 |
1999年 | 22篇 |
1998年 | 86篇 |
1997年 | 55篇 |
1996年 | 34篇 |
1995年 | 28篇 |
1994年 | 20篇 |
1993年 | 22篇 |
1992年 | 13篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 6篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有798条查询结果,搜索用时 15 毫秒
791.
Hayanori Takei Kazuro Furukawa Yoshiharu Yano Yujiro Ogawa 《Journal of Nuclear Science and Technology》2018,55(9):996-1008
Frequent beam trips as experienced in existing high-power proton accelerators may cause thermal fatigue in Accelerator-Driven System components. In order to overcome the beam-trip problem, the beam-trip frequencies were estimated based on operational data on existing accelerators. However, there are at least three methods to calculate the mean time between accidental interruptions (MTBI) for one of the accelerator components, the klystron system. In this study, the four types of MTBI for the klystron systems of an electron/positron injector linear accelerator at the High Energy Accelerator Research Organization were compared based on the same operational data. In the analysis, the stop events of the klystron systems were classified, and the MTBI for the klystron systems was calculated using the Kaplan–Meier (KM) estimation, which is a representative non-parametric reliability method. As a result, the mean value of the MTBI found by the KM estimation was 57.3 ± 6.5 hours. On the other hand, the mean values of the MTBI found by the three traditional methods were 30.9 ± 2.4, 32.0 ± 2.3, and 50.4 ± 5.9 hours. The mean values for the ratios of the MTBI found by the KM estimation, to the MTBI found by the traditional estimation, were 1.67 ± 0.07, 1.58 ± 0.06, and 1.14 ± 0.01, respectively. Although these results are obviously different from traditional results, it appears that the present estimation is suitable for the MTBI for accelerator components. 相似文献
792.
Ryusuke Kado Hisashi Nakagawa Ken Obara Hideo Yano Osamu Ishikawa Tohru Hata 《Journal of Low Temperature Physics》2007,148(5-6):585-589
We have studied phase transition of superfluid 3He in 97.5% porosity aerogel by NMR method. Above 1.0 MPa, superfluid phase transition has been observed. The transition temperature
T
c
a
is strongly suppressed from its bulk value. The Pressure-Temperature diagram suggests that superfluid phase will not appear
below near 0.8 MPa. The A-B phase transition has been observed above 1.3 MPa, below which a state of superfluid phases remains
to be identified. The temperature dependence of NMR frequency shifts Δf in the A-like and the B-like phases are almost linear at pressures below 2.4 MPa. We obtained the differential coefficient
of NMR frequency shifts ∂(Δf)/∂(T/T
c
a
) at 0.9T
c
a
as a function of pressure, and it suggests that superfluid phase will not appear below near 0.8 MPa which is the same pressure
estimated by P-T diagram. 相似文献
793.
M. Yano S. Fujitani K. Nishio Y. Akai M. Kurimura 《Journal of Applied Electrochemistry》1998,28(11):1221-1225
The amount and distribution of additive species in zinc alloy particles containing 0.025wt% bismuth modified with 0.10wt% indium for mercury-free alkaline manganese batteries were examined after storage at various discharging levels at 60°C. The amount of hydrogen gas evolution due to the self-discharging reactions of zinc and the internal cell impedance were also evaluated. The amount of additive species in the zinc alloy particles was found to increase with increasing depth of discharge. Indium was homogeneously distributed on the surface even after partial discharge and also after storage for 1200h at 60°C. This behaviour is considered to contribute to the suppression of hydrogen gas evolution and increase in the internal cell impedance to the same level as when mercury is employed. As a result, mercury-free alkaline manganese batteries showed the same storage characteristics as conventional batteries containing mercury. 相似文献
794.
Balancing mixed-model assembly lines to reduce work overload 总被引:1,自引:0,他引:1
We propose a new line balancing approach for mixed-model assembly lines with an emphasis on how the assignment of tasks to stations affects the ability to construct daily sequences of jobs (customer orders) that provide stable workloads (in a minute-to-minute sense) on the assembly line, while also achieving reasonable workload balance among the stations. The issue of short-term workload stability has received little attention in the assembly line balancing literature. Such stability allows assembly workers to complete their tasks without being rushed and thereby contributes to product quality. We propose a new objective for assembly line balancing that helps to achieve better short-term workload stability and develop a heuristic solution procedure based on filtered beam search for this new objective. Computational results show that for small problems (which can be solved optimally), this approach provides near optimal solutions, and for larger problems, it provides significantly better results than traditional assembly line balancing methods. 相似文献
795.
H Yasuda N Shima N Nakagawa SI Mochizuki K Yano N Fujise Y Sato M Goto K Yamaguchi M Kuriyama T Kanno A Murakami E Tsuda T Morinaga K Higashio 《Canadian Metallurgical Quarterly》1998,139(3):1329-1337
The morphogenesis and remodeling of bone depends on the integrated activity of osteoblasts that form bone and osteoclasts that resorb bone. We previously reported the isolation of a new cytokine termed osteoclastogenesis inhibitory factor, OCIF, which specifically inhibits osteoclast development. Here we report the cloning of a complementary DNA of human OCIF. OCIF is identical to osteoprotegerin (OPG), a soluble member of the tumor-necrosis factor receptor family that inhibits osteoclastogenesis. Recombinant human OPG/OCIF specifically acts on bone tissues and increases bone mineral density and bone volume associated with a decrease of active osteoclast number in normal rats. Osteoblasts or bone marrow-derived stromal cells support osteoclastogenesis through cell-to-cell interactions. A single class of high affinity binding sites for OPG/OCIF appears on a mouse stromal cell line, ST2, in response to 1,25-dihydroxyvitamin D3. An anti-OPG/OCIF antibody that blocks the binding abolishes the biological activity of OPG/OCIF. When the sites are blocked with OPG/OCIF, ST2 cells fail to support osteoclastogenesis. These results suggest that the sites are involved in cell-to-cell signaling between stromal cells and osteoclast progenitors and that OPG/OCIF inhibits osteoclastogenesis by interrupting the signaling through the sites. 相似文献
796.
Starch granules were isolated from rice endosperms of twenty mutants, included two kinds of shrunken (shr) mutant, and two cultivars of their normal counterparts. The shr mutants, EM-20 and Kenkei 2088, showed opposite effects on the amylose content, that is, EM-20 had 5% higher than its normal counterpart and Kenkei 2088 had 3% lower than its one. The amylopectin of EM-20 was composed of slightly shorter chains on the average than its normal one. The gelatinization temperature and heat of gelatinization were affected by the mutation of shr, EM-20. The amylose extender (ae) mutant, Kenkei 2064, had a comparable amylose content with its normal counterpart but its amylopectin had higher content of long chain than the normal one. Twelve kinds of dull (du) mutant reduced the amylose content which varied from 2% to 16%. 相似文献
797.
Toru Hashimoto Satoshi Ishii Reiko Yano Hiroki Miura Ken Sakata Ryo Takeuchi 《Advanced Synthesis \u0026amp; Catalysis》2015,357(18):3901-3916
The complex [Ir(cod)Cl]2/DPPF or rac‐BINAP is an efficient catalyst for the [2+2+2] cycloaddition of α,ω‐diynes with cyanamides. A wide range of cyanamides derived from secondary amines are good coupling partners for α,ω‐diynes. The reaction of unsymmetrical α,ω‐diynes possessing two different internal alkyne moieties with cyanamides is regioselective. A competitive experiment showed that cyanamide is more reactive than nitrile. This higher reactivity of cyanamide than nitrile was analyzed based on density functional theory (DFT) calculations at the B3LYP level.
798.
The combustion wave structure of HMX-CMDB (composite modified double-base) propellants was studied in order to elucidate the gas phase reaction mechanism and to understand the burning rate characteristics. Experiments were conducted to determine the thickness of the reaction zone, gaseous products in the dark zone, and the temperature profile in the combustion waves. The reaction rate in the dark zone is increased by the addition of HMX. This is caused by the equivalence ratio of the oxidizer/fuel in the dark zone shifting towards a stoichiometric ratio when HMX is added. However, the reaction rate in the fizz zone and the heat feedback from the gas phase to the burning surface is decreased by the addition of HMX. Thus, the burning rate of HMX-CMDB propellants decreases when HMX is mixed within double-base propellants. 相似文献