全文获取类型
收费全文 | 1365篇 |
免费 | 39篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 84篇 |
综合类 | 2篇 |
化学工业 | 355篇 |
金属工艺 | 40篇 |
机械仪表 | 28篇 |
建筑科学 | 23篇 |
能源动力 | 72篇 |
轻工业 | 128篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 62篇 |
一般工业技术 | 261篇 |
冶金工业 | 158篇 |
原子能技术 | 66篇 |
自动化技术 | 126篇 |
出版年
2023年 | 11篇 |
2022年 | 19篇 |
2021年 | 40篇 |
2020年 | 22篇 |
2019年 | 17篇 |
2018年 | 25篇 |
2017年 | 23篇 |
2016年 | 48篇 |
2015年 | 28篇 |
2014年 | 43篇 |
2013年 | 88篇 |
2012年 | 67篇 |
2011年 | 91篇 |
2010年 | 56篇 |
2009年 | 59篇 |
2008年 | 60篇 |
2007年 | 70篇 |
2006年 | 64篇 |
2005年 | 38篇 |
2004年 | 45篇 |
2003年 | 35篇 |
2002年 | 22篇 |
2001年 | 22篇 |
2000年 | 24篇 |
1999年 | 28篇 |
1998年 | 60篇 |
1997年 | 46篇 |
1996年 | 31篇 |
1995年 | 28篇 |
1994年 | 21篇 |
1993年 | 20篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 9篇 |
1968年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有1408条查询结果,搜索用时 15 毫秒
991.
992.
The authors irradiated PTFE (polytetrafluoroethylene) with low‐energy nitrogen ions (100 eV) for surface modification. However, PTFE cannot be expected to show improvement in adhesive strength because it is a degradation‐prone polymer and surface fatigue is produced by ion irradiation. We focused on cross‐linked structure to solve this problem. PTFE was changed from a degradation‐prone polymer into a cross‐linked polymer by raising the temperature above the glass‐transition temperature during ion irradiation. As a result, the formation of CF3 bonds was inhibited and degradation was prevented by ion irradiation above the glass‐transition temperature. In addition, combined consideration of the C1s spectrum and the density profile suggests that a cross‐linked structure is effective for improvement of adhesive strength. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(4): 1–7, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21225 相似文献
993.
Toru Yamada Anurag Kumar Yutaka Asako Otto J. Gregory 《Numerical Heat Transfer, Part A: Applications》2013,63(8):651-665
Dissipative particle dynamics (DPD) with energy conservation was applied to simulate forced convection in parallel-plate channels with boundary conditions of constant wall temperature (CWT) and constant wall heat flux (CHF). DPD is a coarse-grained version of molecular dynamics. An additional equation for energy conservation was solved along with conventional DPD equations, where inter-particle heat flux accounts for changes in mechanical and internal energies when particles interact with surrounding particles. The solution domain was considered to be two–dimensional with periodic boundary condition in the flow direction and additional layers of particles on the top and bottom of the channel to apply no-slip and wall temperature boundary conditions. The governing equation for energy conservation was modified based on periodic fully developed velocity and temperature conditions. The results were shown via velocity and temperature profiles across the channel cross-section. The Nusselt numbers for CWT and CHF were calculated from the temperature gradient at the wall using a second order accurate forward difference approximation. The results agreed well with the exact solutions to within 2.3%. 相似文献
994.
Haifeng Gao Toshiro Matsumoto Toru Takahashi Hiroshi Isakari 《Engineering Analysis with Boundary Elements》2013,37(6):914-923
This paper presents accurate numerical solutions for nonlinear eigenvalue analysis of three-dimensional acoustic cavities by boundary element method (BEM). To solve the nonlinear eigenvalue problem (NEP) formulated by BEM, we employ a contour integral method, called block Sakurai–Sugiura (SS) method, by which the NEP is converted to a standard linear eigenvalue problem and the dimension of eigenspace is reduced. The block version adopted in present work can also extract eigenvalues whose multiplicity is larger than one, but for the complex connected region which includes a internal closed boundary, the methodology yields fictitious eigenvalues. The application of the technique is demonstrated through the eigenvalue calculation of sphere with unique homogenous boundary conditions, cube with mixed boundary conditions and a complex connected region formed by cubic boundary and spherical boundary, however, the fictitious eigenvalues can be identified by Burton–Miller's method. These numerical results are supported by appropriate convergence study and comparisons with close form. 相似文献
995.
Yoshihiro Kanno 《Optimization and Engineering》2013,14(1):61-96
A tensegrity structure is a prestressed pin-jointed structure consisting of discontinuous struts and continuous cables. For exploring new configurations of tensegrity structures, this paper addresses a topology optimization problem of tensegrity structures under the compliance constraint and the stress constraints. It is assumed that a cable loosens and loses the elongation stiffness when its tensile prestress vanishes due to the applied external load. It is shown that the topology optimization problem can be formulated as a mixed integer linear programming (MILP) problem. The proposed method does not require any connectivity information of cables and struts to be known in advance. Numerical experiments illustrate that various configurations of tensegrity structures can be found as the optimal solutions. 相似文献
996.
Muhammad Imran Al-haq Eric Lebrasseur Hidenori Tsuchiya Toru Torii 《Crystallography Reviews》2013,19(1):29-64
New methods for improving the quality of protein crystals are always being sought. Electric-field-induced protein crystallization is one of them. A few devices have already been developed. We conducted a series of experiments for several years and fabricated many electrode panels to realize a device for electric-field induced protein crystallization for the microbatch method. The review mainly deals with the application of the various devices that have so far been reported in the literature on the subject, including an overview of the work that has already been conducted. The factors affecting the electric-field-induced protein crystallization are also discussed. 相似文献
997.
Motomu Suzuki Toru Yamamoto Hiroyuki Fukaya Kenya Suyama Gunzo Uchiyama 《Journal of Nuclear Science and Technology》2013,50(12):1161-1176
As part of a validation study of burnup calculations of BWR cores, lattice physics analyses were performed on burnups and isotopic compositions of U, Pu and fission product nuclides measured on five samples taken from 9 × 9 BWR fuel assemblies. Burnup calculations in infinite assembly geometry were carried out using MVP-BURN and SRAC codes coupled with major nuclear data libraries. The burnups determined based on the Nd-148 method were from 27.9 to 64.2 GWd/t. The typical relative differences in isotopic compositions (atom/Total-U) between the burnup calculations and measurements were ?2 ~ 19% for 234U, ?20 ~ 3% for 235U, ?1.5 ~ 0.1% for 236U, ?0.04 ~ 0.02% for 238U, ?4 ~ 11% for 238Pu, ?11 ~ ?2% for 239Pu, ?3 ~ 0% for 240Pu, ?12 ~ ?2% for 241Pu and ?2 ~ 3% for 242Pu. They were ?2 ~ 2% for Nd isotopes, ?15 ~ 7% for Eu isotopes, ?13 ~ 1% for Cs isotopes, ?13 ~ 8% for Sm isotopes, 0 ~ 7% for 147Pm, ?7 ~ ?2% for 95Mo, ?2 ~ ?1% for101Ru and 0 ~ 4% for 103Rh. 相似文献
998.
Takuya Umano Kenichi Yoshioka Toru Obara 《Journal of Nuclear Science and Technology》2013,50(5):608-625
For nuclear critical experiments, it is essential to certify similarities of the experiment with the objective of the actual reactor conditions or actual reactor equipment. To judge the applicability of the experimental data, the concept of a “representativity factor” has recently been adopted in the critical experiment field, particularly for fast breeder reactors and future reactor studies. In this study, we extended this concept to the design of a light water reactor system. We developed a new numerical evaluation method and a calculation system. The method is based on a linear combination of the sensitivity coefficient vector of an experiment in which the representativity factor to the target system is maximized to utilize experimental data effectively. Simultaneously, using the measurement data of critical experiments, the method enables us to evaluate calculation errors caused by errors or uncertainties of physical parameters. The derivation of the new calculation method is explained first. We then qualify it with a sample calculation, presenting numerical results for three kinds of critical experiments conducted at the Toshiba Nuclear Critical Assembly facility. Finally, the results are compared with those of an extended bias factor method to clarify the performance of the new method. 相似文献
999.
Huagang Wang Hideaki Takashima Yozo Miyakawa Yoshinori Kanno 《Science and Technology of Advanced Materials》2005,6(8):921-926
Recently, airborne virus infections have emerged as some of the most challenging medical problems. To prevent the threat of infection, the processes of sterilization have been studied widely. Microwave sterilization has many advantages in comparison with conventional methods. It is able to raise the temperature of a material in a short time and selectively heat the material. This results in the reduction of usage and the rapid completion of sterilization. We developed a novel microwave sterilization system that can raise the temperature in quite a short time using a lower microwave power (100 W). Filters made with Kao wool (Al2O3) were coated with TiO2 (anatase) by sol–gel method and used to trap microorganisms. In addition, these filters were coated with Pt or Ag by impregnated method. We also prepared a Tyranno-fiber textile filter and a honeycomb SiC filter. Two microorganisms, Bacillus subtilis ATCC 9372 and Bacillus stearothermophilus ATCC 7953, were used in this experiment, where either microorganism was loaded onto a filter. After irradiation, filters loaded with B. subtilis and B. stearothermophilus were incubated for 48 h in a TSB medium (Bacto™ Tryptic Soy Broth, Becton, Dickinson and company sparks, MD) at 37 and 56 °C, respectively. B. subtilis and B. stearothermophilus loaded on to Ag-impregnated filters were sterilized in 30 and 15 s, respectively. The Tyranno-fiber textile filter and the honeycomb SiC also filter showed effective microwave sterilization. These results showed that this system could sterilize B. subtilis and B. stearothermophilus in quite a short time and that microwave absorbable materials are effective as microwave sterilization filters. 相似文献
1000.
Ejima K Liu J Oshima Y Hirooka K Shimanuki S Yokota Y Hemmi H Nakayama T Nishino T 《Journal of Bioscience and Bioengineering》2004,98(6):445-451
A gene coding for an esterase (SshEstI, 915 bp in length) of the thermoacidophilic archaeon Sulfolobus shibatae DSM5389 was cloned, sequenced, and overexpressed in Escherichia coli JM109 cells as a soluble, catalytically active protein. The deduced amino acid sequence of SshEstI was consistent with a protein containing 305 amino acid residues with a molecular mass of 33 kDa. Sequence comparison studies indicated that SshEstI could be a member of the hormone-sensitive lipase family, in that it had the highest sequence similarity to esterases from Sulfolobus solfataricus (90% identity) and Archaeoglobus fulgidus (42%) and a lipase from Pseudomonas sp. B11-1 (38%). The recombinant enzyme was highly thermostable and retained more than 70% of its initial activity after incubation at 90 degrees C and pH 7.0 for 30 min. The recombinant enzyme catalyzed the hydrolysis of p-nitrophenyl (p-NP) esters with C2-C16 acyl chains but not the hydrolysis of triacylglycerides such as tributyrin and triolein. The enzymatic hydrolysis of p-NP acetate proceeded in a linear manner with time, whereas that of p-NP esters with acyl chains of C5 or longer showed a biphasic profile, where a rapid release of p-nitrophenol ( approximately 3 min) was followed by a slow, sustained release. These non-linear kinetics may be explained in terms of a very slow, presteady-state burst phenomenon of p-nitrophenol release or a hysteretic behavior of SshEstI with these substrates. 相似文献