全文获取类型
收费全文 | 2652篇 |
免费 | 93篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 131篇 |
综合类 | 3篇 |
化学工业 | 338篇 |
金属工艺 | 64篇 |
机械仪表 | 50篇 |
建筑科学 | 147篇 |
矿业工程 | 10篇 |
能源动力 | 86篇 |
轻工业 | 255篇 |
水利工程 | 18篇 |
石油天然气 | 13篇 |
武器工业 | 1篇 |
无线电 | 302篇 |
一般工业技术 | 321篇 |
冶金工业 | 297篇 |
原子能技术 | 17篇 |
自动化技术 | 709篇 |
出版年
2023年 | 12篇 |
2022年 | 26篇 |
2021年 | 43篇 |
2020年 | 24篇 |
2019年 | 43篇 |
2018年 | 85篇 |
2017年 | 59篇 |
2016年 | 52篇 |
2015年 | 46篇 |
2014年 | 90篇 |
2013年 | 197篇 |
2012年 | 171篇 |
2011年 | 136篇 |
2010年 | 172篇 |
2009年 | 180篇 |
2008年 | 208篇 |
2007年 | 130篇 |
2006年 | 157篇 |
2005年 | 140篇 |
2004年 | 73篇 |
2003年 | 97篇 |
2002年 | 83篇 |
2001年 | 42篇 |
2000年 | 51篇 |
1999年 | 54篇 |
1998年 | 34篇 |
1997年 | 34篇 |
1996年 | 30篇 |
1995年 | 31篇 |
1994年 | 21篇 |
1993年 | 23篇 |
1992年 | 24篇 |
1991年 | 17篇 |
1990年 | 19篇 |
1989年 | 20篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 16篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 15篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
排序方式: 共有2762条查询结果,搜索用时 15 毫秒
91.
In this reply, the authors explore several issues raised by I. Kirsch (2004; see record 2004-11156-008) concerning their original article (S. Stewart-Williams & J. Podd, 2004; see record 2004-11156-007), which dealt with the roles of expectancy and classical conditioning in the placebo effect. The only notable disagreement concerns a definitional issue, namely, Stewart-Williams and Podd's claim that the placebo concept can be extended to inert psychotherapies. The authors defend this claim against the criticisms Kirsch raised. In addition, they comment on the suggestion that nonconscious learning processes play only a small role in human placebo effects, arguing that there are theoretical reasons to expect these processes to be more important than has previously been recognized. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
92.
Satellite radar remote sensing of seasonal growing seasons for boreal and subalpine evergreen forests 总被引:2,自引:0,他引:2
John S. Kimball Kyle C. McDonald Steve E. Frolking 《Remote sensing of environment》2004,90(2):243-258
We evaluated whether satellite radar remote sensing of landscape seasonal freeze-thaw cycles provides an effective measure of active growing season timing and duration for boreal and subalpine evergreen forests. Landscape daily radar backscatter measurements from the SeaWinds scatterometer on-board the QuikSCAT satellite were evaluated across a regional network of North American coniferous forest sites for 2000 and 2001. Radar remote sensing measurements of the initiation and length of the growing season corresponded closely with both site measurements and ecosystem process model (BIOME-BGC) simulations of these parameters because of the sensitivity of the Ku-band scatterometer to snow cover freeze-thaw dynamics and associated linkages between growing season initiation and the timing of seasonal snowmelt. In contrast, remote sensing estimates of the timing of growing season termination were either weakly or not significantly associated with site measurements and model simulation results, due to the relative importance of light availability and other environmental controls on stand phenology in the fall. Regional patterns of estimated annual net primary production (NPP) and component photosynthetic and autotrophic respiration rates for the evergreen forest sites also corresponded favorably with remote sensing estimates of the seasonal timing of spring thaw and associated growing season length, indicating the importance of these parameters in determining spatial and temporal patterns of NPP and the potential utility of satellite radar remote sensing for regional monitoring of the terrestrial biosphere. 相似文献
93.
The increasing gap in performance between processors and main memory has made effective instructions prefetching techniques more important than ever. A major deficiency of existing prefetching methods is that most of them require an extra port to I-cache. A recent study by Rivers et al. [19] shows that this factor alone explains why most modern microprocessors do not use such hardware-based I-cache prefetch schemes. The contribution of this paper is two-fold. First, we present a method that does not require an extra port to I-cache. Second, the performance improvement for our method is greater than the best competing method BHGP [23] even disregarding the improvement from not having an extra port. The three key features of our method that prevent the above deficiencies are as follows. First, late prefetching is prevented by correlating misses to dynamically preceding instructions. For example, if the I-cache miss latency is 12 cycles, then the instruction that was fetched 12 cycles prior to the miss is used as the prefetch trigger. Second, the miss history table is kept to a reasonable size by grouping contiguous cache misses together and associated them with one preceding instruction, and therefore, one table entry. Third, the extra I-cache port is avoided through efficient prefetch filtering methods. Experiments show that for our benchmarks, chosen for their poor I-cache performance, an average improvement of 9.2% in runtime is achieved versus the BHGP methods [23], while the hardware cost is also reduced. The improvement will be greater if the runtime impact of avoiding an extra port is considered. When compared to the original machine without prefetching, our method improves performance by about 35% for our benchmarks. 相似文献
94.
Study of the impact of a new hurdle technology composed of electro‐activated solution and low heat treatment on the canned pea and corn quality and microbial safety 下载免费PDF全文
Viacheslav Liato Steve Labrie Marzouk Benali Mohammed Aïder 《International Journal of Food Science & Technology》2016,51(1):180-193
The objective of this work was to evaluate the quality of sterilised canned pea and corn in electro‐activated brine solutions at moderate temperatures. The lowest change in vitamin C was associated with the lowest heat treatment, while the short treatment time resulted in significant changes in texture and colour of vegetables. Best texture profile was obtained with the acid electro‐activated brine solution for pea and corn. The neutral electro‐activated brine solution resulted in a less firm texture for pea and corn. The green colour and brightness of canned pea were higher when neutral solution was used (a* = ?8.4 ± 0.3) than for the acidic one (a* = ?3.7 ± 0.6). The yellowness of corn was better with the neutral electro‐activated brine solution (b* = 36.32 ± 1.24) than with the acidic one (b* = 28.44 ± 2.39). Thirty‐three percent decrease of energy consumption was obtained using the electro‐activation technology. 相似文献
95.
96.
97.
98.
99.
Three-dimensional distinct element modelling and dynamic runout analysis of a landslide in gneissic rock, British Columbia, Canada 总被引:1,自引:1,他引:0
Marc-André Brideau Scott McDougall Doug Stead Steve G. Evans Réjean Couture Kevin Turner 《Bulletin of Engineering Geology and the Environment》2012,71(3):467-486
The McAuley Creek Landslide is a 6?million m3 gneissic rock slope failure that occurred in British Columbia (Canada) in late May–early June 2002. The geological strength index was used to characterize the quality of the overall rock mass and its reduced (damaged) quality near tectonic structures and alteration zones. Potential slope failure mechanisms were investigated using four analysis techniques including: kinematic analysis, surface wedge limit equilibrium (combination) analysis, block theory and three-dimensional distinct element models. Results from all four analyses suggested that the dominant slope failure mechanism was wedge sliding along the intersection of the gneissic foliation and a steeply dipping discontinuity set striking perpendicular to the slope. Of the 6?million m3 of material involved in the landslide, an estimated 5 million?m3 was deposited immediately below the source area against the opposite valley wall, with the remaining 1 million m3 travelling an additional 1.6?km downstream. The runout behaviour was investigated using a three-dimensional dynamic analysis code. 相似文献
100.
Nicolai N. Martovetsky David K. Irick Steve J. Kenney 《Fusion Engineering and Design》2013,88(9-10):1601-1604
The terminations of the Central Solenoid (CS) modules are connected to the bus extensions by joints located outside the CS in the gap between the CS and torodial field (TF) assemblies. These joints have very strict space limitations. Low resistance is a common requirement for all ITER joints. In addition, the CS bus joints will experience and must be designed to withstand significant variation in the magnetic field of several tenths of a Tesla per second during initiation of plasma. The joint resistance is specified to be less than 4 nΩ.The joints also have to be soldered in the field and designed with the possibility to be installed and dismantled in order to allow cold testing in the cold test facility. We have developed coaxial joints that meet these requirements and have demonstrated the feasibility to fabricate and assemble them in the vertical configuration. We introduced a coupling cylinder with superconducting strands soldered to the surface of the cable that can be installed in the ITER assembly hall and at the cold test facility. This cylinder serves as a transition area between the CS module and the bus extension.We made two racetrack samples and tested four bus joints in our Joint Test Apparatus. Resistance of the bus joints was measured by a decay method and by a microvoltmeter; the value of the current was measured by the Hall probes. This measurement method was verified in the previous tests. The resistance of the joints varied insignificantly from 1.5 to 2 nΩ.One of the challenges associated with a soldered joint is the inability to use corrosive chemicals that are difficult to clean. This paper describes our development work on cable preparation, chrome removal, compaction, soldering, and final assembly and presents the test results. 相似文献