全文获取类型
收费全文 | 759篇 |
免费 | 10篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 27篇 |
综合类 | 2篇 |
化学工业 | 188篇 |
金属工艺 | 31篇 |
机械仪表 | 12篇 |
建筑科学 | 24篇 |
能源动力 | 29篇 |
轻工业 | 107篇 |
石油天然气 | 1篇 |
无线电 | 43篇 |
一般工业技术 | 170篇 |
冶金工业 | 35篇 |
原子能技术 | 48篇 |
自动化技术 | 58篇 |
出版年
2022年 | 26篇 |
2021年 | 20篇 |
2020年 | 17篇 |
2019年 | 9篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 11篇 |
2015年 | 10篇 |
2014年 | 23篇 |
2013年 | 38篇 |
2012年 | 34篇 |
2011年 | 47篇 |
2010年 | 29篇 |
2009年 | 37篇 |
2008年 | 31篇 |
2007年 | 32篇 |
2006年 | 18篇 |
2005年 | 32篇 |
2004年 | 31篇 |
2003年 | 27篇 |
2002年 | 30篇 |
2001年 | 16篇 |
2000年 | 17篇 |
1999年 | 12篇 |
1998年 | 21篇 |
1997年 | 18篇 |
1996年 | 18篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 17篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1968年 | 1篇 |
排序方式: 共有775条查询结果,搜索用时 0 毫秒
761.
A. Nakayama N. Kokubo T. Ishida F. Kuwahara 《Numerical Heat Transfer, Part A: Applications》2013,63(2):155-165
A conjugate numerical model has been proposed to investigate the problem of cooling a fluid flowing through a spiral coil immersed in a chilled water container, which is common in many beverage dispensers. A simple axisymmetric numerical procedure is described to determine the temperature of the fluid in the spiral coil and that of the coil surface. A one-dimensional heat balance equation for the fluid within the coil is utilized to update the fluid and wall surface temperatures, which are needed to calculate the temperature field in the water container with solid ice walls. The SIMPLE algorithm has been adopted along with the standard k-epsilon turbulence model equations. A reasonably good agreement between the numerical predictions and experimental results has been achieved. 相似文献
762.
Explicit algebraic expressions are first proposed to predict easily and precisely the thermal-expansion coefficients of unidirectional reinforced plastics. They are given as functions of the thermal and elastic properties of the constituent materials and of the fiber-volume fraction. They are derived by considering circular anisotropic fibers arranged in a hexagonal array in a matrix. Then, analytical expressions are derived for the thermal-expansion coefficients and curing stresses in filament-wound laminated composites under the assumption of elastic behavior and within the framework of laminated plate theory. Experiments on carbon-fiber/epoxy composite cylinders reinforced by helical and circumferential windings show good agreement with the calculated values. The residual stresses induced by curing are found not to be negligible compared with the low tensile strength transverse to the fibers. Such algebraic expressions for thermal coefficients, together with those for elastic moduli and failure criterion proposed by one of the authors, seem to be of use in the tailored design of laminated composite structures in a closed form, which elucidate the effects of various sorts of constitutive parameters. 相似文献
763.
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
764.
Masayuki Fujimoto Yuji Nishi Toshimasa Suzuki Hisashi Shigetani Shoichi Sekiguchi 《Journal of the American Ceramic Society》1998,81(9):2477-2480
Coherent copper-metal precipitates at grains adjacent to the Σ= 5 coincident-site lattice (CSL) boundary in a low-temperature-fired Ni-Zn-Cu ferrite have been observed and analyzed using analytical electron microscopy. This precipitation behavior is related to the copper solubility limits in the Ni-Zn-Cu ferrite during cooling after sintering, and preferential solute segregation may be dominant at stacking faults rather than at the Sigma = 5 CSL boundary. Copper-metal precipitates have a 〈100〉 matrix ∥〈100〉 Cu coherent relationship to the ferrite matrix. 相似文献
765.
766.
In this study, we investigated the efficiency of dissolved methane (D-CH4) collection by degasification from the effluent of a bench-scale upflow anaerobic sludge blanket (UASB) reactor treating synthetic wastewater. A hollow-fiber degassing membrane module was used for degasification. This module was connected to the liquid outlet of the UASB reactor. After chemical oxygen demand (COD) removal efficiency of the UASB reactor became stable, D-CH4 discharged from the UASB reactor was collected. Under 35 °C and a hydraulic retention time (HRT) of 10 h, average D-CH4 concentration could be reduced from 63 mg COD L−1 to 15 mg COD L−1; this, in turn, resulted in an increase in total methane (CH4) recovery efficiency from 89% to 97%. Furthermore, we investigated the effects of temperature and HRT of the UASB reactor on degasification efficiency. Average D-CH4 concentration was as high as 104 mg COD L−1 at 15 °C because of the higher solubility of CH4 gas in liquid; the average D-CH4 concentration was reduced to 14 mg COD L−1 by degasification. Accordingly, total CH4 recovery efficiency increased from 71% to 97% at 15 °C as a result of degasification. Moreover, degasification tended to cause an increase in particulate COD removal efficiency. The UASB reactor was operated at the same COD loading rate, but different wastewater feed rates and HRTs. Although average D-CH4 concentration in the UASB reactor was almost unchanged (ca. 70 mg COD L−1) regardless of the HRT value, the CH4 discharge rate from the UASB reactor increased because of an increase in the wastewater feed rate. Because the D-CH4 concentration could be reduced down to 12 ± 1 mg COD L−1 by degasification at an HRT of 6.7 h, the CH4 recovery rate was 1.5 times higher under degasification than under normal operation. 相似文献
767.
768.
769.
Hideyuki Hara Junji Chida Agriani Dini Pasiana Keiji Uchiyama Yutaka Kikuchi Tomoko Naito Yuichi Takahashi Junji Yamamura Hisashi Kuromatsu Suehiro Sakaguchi 《International journal of molecular sciences》2021,22(6)
Prions are infectious agents causing prion diseases, which include Creutzfeldt–Jakob disease (CJD) in humans. Several cases have been reported to be transmitted through medical instruments that were used for preclinical CJD patients, raising public health concerns on iatrogenic transmissions of the disease. Since preclinical CJD patients are currently difficult to identify, medical instruments need to be adequately sterilized so as not to transmit the disease. In this study, we investigated the sterilizing activity of two oxidizing agents, ozone gas and vaporized hydrogen peroxide, against prions fixed on stainless steel wires using a mouse bioassay. Mice intracerebrally implanted with prion-contaminated stainless steel wires treated with ozone gas or vaporized hydrogen peroxide developed prion disease later than those implanted with control prion-contaminated stainless steel wires, indicating that ozone gas and vaporized hydrogen peroxide could reduce prion infectivity on wires. Incubation times were further elongated in mice implanted with prion-contaminated stainless steel wires treated with ozone gas-mixed vaporized hydrogen peroxide, indicating that ozone gas mixed with vaporized hydrogen peroxide reduces prions on these wires more potently than ozone gas or vaporized hydrogen peroxide. These results suggest that ozone gas mixed with vaporized hydrogen peroxide might be more useful for prion sterilization than ozone gas or vaporized hydrogen peroxide alone. 相似文献
770.
Yoshimori Kento Okuda Chika Ohta Shinji Ômura Hisashi 《Journal of chemical ecology》2022,48(5-6):518-530
Journal of Chemical Ecology - The common grass yellow Eurema mandarina has a characteristic patch (sex brand) composed of specialized scales (androconia) and wing intermembranous cells on the... 相似文献