全文获取类型
收费全文 | 5946篇 |
免费 | 588篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 64篇 |
综合类 | 4篇 |
化学工业 | 1646篇 |
金属工艺 | 191篇 |
机械仪表 | 420篇 |
建筑科学 | 86篇 |
矿业工程 | 7篇 |
能源动力 | 265篇 |
轻工业 | 492篇 |
水利工程 | 22篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 976篇 |
一般工业技术 | 1394篇 |
冶金工业 | 230篇 |
原子能技术 | 71篇 |
自动化技术 | 669篇 |
出版年
2024年 | 3篇 |
2023年 | 84篇 |
2022年 | 105篇 |
2021年 | 208篇 |
2020年 | 181篇 |
2019年 | 234篇 |
2018年 | 205篇 |
2017年 | 233篇 |
2016年 | 261篇 |
2015年 | 236篇 |
2014年 | 335篇 |
2013年 | 421篇 |
2012年 | 497篇 |
2011年 | 527篇 |
2010年 | 367篇 |
2009年 | 335篇 |
2008年 | 327篇 |
2007年 | 264篇 |
2006年 | 245篇 |
2005年 | 192篇 |
2004年 | 172篇 |
2003年 | 181篇 |
2002年 | 124篇 |
2001年 | 120篇 |
2000年 | 81篇 |
1999年 | 95篇 |
1998年 | 101篇 |
1997年 | 72篇 |
1996年 | 61篇 |
1995年 | 44篇 |
1994年 | 26篇 |
1993年 | 30篇 |
1992年 | 27篇 |
1991年 | 15篇 |
1990年 | 20篇 |
1989年 | 23篇 |
1988年 | 15篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1941年 | 1篇 |
排序方式: 共有6544条查询结果,搜索用时 15 毫秒
31.
Uniaxial tensile tests in various directions following uniaxial extension, equibiaxial stretching or plane strain rolling have been performed to study the effects of changes in strain path on the anisotropy of yield stresses of aluminium-killed low-carbon steel and 70-30 brass sheets. The anisotropy could be predicted from the specimen textures, if dislocation structure were equiaxed, as in the case of equibiaxial stretching. However, elongated dislocation cell structures, developed in the steel specimens prestrained in uniaxial tension or plane strain rolling, gave rise to the second-stage yield stresses higher than predicted from textures in the directions different from the maximum prestrain direction. Planar dislocation structures in the brass specimens prestrained in uniaxial tension or plane strain rolling gave the second-stage yield stresses lower than predicted from the textures in the directions different from the maximum prestrain direction. The phenomena are discussed based on textures and dislocation structures. 相似文献
32.
A new physics analysis procedure has been developed for a prismatic very high temperature gas-cooled reactor based on a conventional two-step procedure for the PWR physics analysis. The HELIOS and MASTER codes were employed to generate the coarse group cross sections through a transport lattice calculation, and to perform the 3-dimensional core physics analysis by a nodal diffusion calculation, respectively. Physics analysis of the prismatic VHTRs involves particular modeling issues such as a double heterogeneity of the coated fuel particles, a neutron streaming in the coolant channels, a strong core-reflector interaction, and large spectrum shifts due to changes of the surrounding environment and state parameters. Double heterogeneity effect was considered by using a recently developed reactivity-equivalent physical transformation method. Neutron streaming effect was quantified through 3-dimensional Monte Carlo transport calculations by using the MCNP code. Strong core-reflector interaction could be handled by applying an equivalence theory to the generation of the reflector cross sections. The effects of a spectrum shift could be covered by optimizing the coarse energy group structure. A two-step analysis procedure was established for the prismatic VHTR physics analysis by combining all the methodologies described above. The applicability of our code system was tested against core benchmark problems. The results of these benchmark tests show that our code system is very accurate and practical for a prismatic VHTR physics analysis. 相似文献
33.
34.
Tae-Sung Jung Do-Chan Choi Sung-Hee Cho Myong-Jae Kim Seung-Keun Lee Byung-Soon Choi Jin-Sun Yum San-Hong Kim Dong-Gi Lee Jong-Chang Son Myung-Sik Yong Heung-Kwun Oh Sung-Bu Jun Woung-Moo Lee Haq E. Kang-Deog Suh Ali S.B. Hyung-Kyu Lim 《Solid-State Circuits, IEEE Journal of》1997,32(11):1748-1757
A 3.3-V 16-Mb nonvolatile memory having operation virtually identical to DRAM with package pin compatibility has been developed. Read and write operations are fully DRAM compatible except for a longer RAS precharge time after write. Fast random access time of 63 ns with the NAND flash memory cell is achieved by using a hierarchical row decoder scheme and a unique folded bit-line architecture which also allows bit-by-bit program verify and inhibit operation. Fast page mode with a column address access time of 21 ns is achieved by sensing and latching 4 k cells simultaneously. To allow byte alterability, nonvolatile restore operation with self-contained erase is developed. Self-contained erase is word-line based, and increased cell disturb due to the word-line based erase is relaxed by adding a boosted bit-line scheme to a conventional self-boosting technique. The device is fabricated in a 0.5-μm triple-well, p-substrate CMOS process using two-metal and three-poly interconnect layers. A resulting die size is 86.6 mm2, and the effective cell size including the overhead of string select transistors is 2.0 μm2 相似文献
35.
Isothermal melt spinning experiments have been conducted using two polyethylene melts of low density (LDPE) and high density
(HDPE) to produce steady state spinline profiles. The data revealed the threadline extensional viscosity exhibiting a contrasting
picture : extension thickening behavior for LDPE and extension thinning one for HDPE. A White-Metzner model having a strain
rate-dependent relaxation time was then found to be able to simulate this dichotomy in melt spinning fairly well: the fluids
whose relaxation times have smaller strain rate-dependence can fit LDPE data with extension thickening extensional viscosity
whereas the fluids whose relaxation times have larger strain rate-dependence can fit HDPE data with extension thinning extensional
viscosity. This dichotomous nature of viscoelastic fluids is also believed to be able to explain other similar contrasting
phenomena exhibited by polymer melts, such as vortex/no vortex in entry flows, cohesive/ductile fracture modes in extension,
and more/less stable draw resonance than Newtonian fluids. 相似文献
36.
Young-Jin Kim Jin-Ho Son Hae-Dong Chung Joon-Gu Kim 《Journal of Mechanical Science and Technology》1994,8(2):198-205
This paper describes the development strategy of a prototype expert system, called RViES, for the reactor vessel integrity.
The main objectives of the system are to assist engineers to perform fatigue and fracture mechanics analyses of reactor vessels
quickly and accurately. The system consists of three parts; user interface, knowledge base and inference engine. Various rules
recommended in codes and standards are stored in the knowledge base. Several case studies were performed to check the usefulness
of the system. 相似文献
37.
JK Kang SW Lee MW Baik BC Son YK Hong CK Jung KH Ryu 《Canadian Metallurgical Quarterly》1998,14(7):297-301
Accurate assessment and replacement of blood loss and fluid-electrolyte deficit during craniosynostosis repair is difficult owing to patient size and the diversity of surgical technique. Forty-three patients undergoing primary craniosynostosis repair over a 10-year period were studied retrospectively to determine blood loss and fluid deficit and to assess blood transfusion practices during both intraoperative and postoperative periods. Blood loss was calculated on the basis of estimated red cell mass (ERCM) and fluid-electrolyte imbalance was investigated with blood samplings. Blood transfusion was considered appropriate if the postoperative or posttransfusion ERCM was within 12% of the preoperative value. Estimated fluid requirement (EFR) was used in 4 ml kg(-1) h(-1) except for neonates. Intraoperatively, 80% of all patients were appropriately managed with respect to blood transfusion and EFR. Postoperatively only 20% of the patients receiving transfusions were transfused appropriately. In 23.3% of these patients (10/43) unexpected respiratory distress developed immediately after their recovery from the anesthesia. With the measurement of estimated blood volume and allowable blood loss, appropriate transfusion could be achieved for the successful treatment of the primary craniosynostosis. 相似文献
38.
Wu Li Yann-Hang Lee Wei-Tek Tsai Jingjing Xu Young-Sung Son Jun-Hee Park Kyung-Duk Moon 《Service Oriented Computing and Applications》2012,6(1):65-79
A smart home usually has a variety of devices or home appliance, instead of designing software for a specific home, this paper
proposes a service-oriented framework with a set of ontology systems to support service and device publishing, discovery of
devices and their services, composition of control software using existing control services that wrap devices, deployment,
and execution of the composed service in an computing environment, monitoring the execution, and recovery from device failure.
The ontology systems specify semantic information about devices, services, and workflows used in various smart home, and users
can compose and recompose services for their specific needs. New devices, workflows, and services can be added into ontology.
Most of the steps in this process can be automated including code generation. For example, service composition will be carried
out in three steps: abstract workflow design, function construction, and device discovery, and different codes can be generated
for different computing platforms such as Java and Open Services Gateway initiative environments. In this way, a variety of
smart home can be constructed rapidly using the framework by discovery and composition using existing services and workflows.
This paper illustrates this framework using a media control example to illustrate the ontology, discovery, composition, deployment,
execution, monitoring, and recovery. 相似文献
39.
Neural Computing and Applications - In recent years, the design of social software UI has become a design research focus in the field of design. Color affects many factors in UI design. However,... 相似文献
40.
Jung Nam Bae Jin Young Kim Geon Kim Yong Tae Lee Jae Sang Cha 《Multimedia Tools and Applications》2012,57(2):359-372
Recently, watermarking based data transmission techniques using terrestrial digital TV signal have been proposed since they
are also cost-free and can overcome the limitations of GPS. However, in the previous watermarking based methods, the detection
accuracy is low and additional data rate is too low. Thus, we propose the throughput enhancement method by employing the TZCD-MBOK
watermarking technique in T-DMB system. By applying the proposed scheme to T-DMB, it allows additional data transmission for
disaster broadcasting and improves efficiency of data transmission in shadow region and indoor to mobile environment through
watermarking spread code. From the simulation results, we confirm the proposed watermarking scheme affected on the existing
T-DMB signal. Moreover, it was also confirmed that the system capacity increases as the power of additional watermarking signal
rose. The results of the paper can be applied to wireless multimedia digital broadcasting systems. 相似文献