全文获取类型
收费全文 | 1401篇 |
免费 | 37篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 74篇 |
综合类 | 6篇 |
化学工业 | 356篇 |
金属工艺 | 28篇 |
机械仪表 | 35篇 |
建筑科学 | 27篇 |
矿业工程 | 1篇 |
能源动力 | 71篇 |
轻工业 | 129篇 |
水利工程 | 2篇 |
无线电 | 130篇 |
一般工业技术 | 259篇 |
冶金工业 | 192篇 |
原子能技术 | 42篇 |
自动化技术 | 90篇 |
出版年
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 20篇 |
2020年 | 9篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 20篇 |
2016年 | 20篇 |
2015年 | 18篇 |
2014年 | 36篇 |
2013年 | 63篇 |
2012年 | 38篇 |
2011年 | 71篇 |
2010年 | 55篇 |
2009年 | 78篇 |
2008年 | 67篇 |
2007年 | 55篇 |
2006年 | 54篇 |
2005年 | 49篇 |
2004年 | 48篇 |
2003年 | 50篇 |
2002年 | 43篇 |
2001年 | 31篇 |
2000年 | 27篇 |
1999年 | 33篇 |
1998年 | 83篇 |
1997年 | 68篇 |
1996年 | 49篇 |
1995年 | 39篇 |
1994年 | 25篇 |
1993年 | 25篇 |
1992年 | 21篇 |
1991年 | 29篇 |
1990年 | 16篇 |
1989年 | 15篇 |
1988年 | 23篇 |
1987年 | 5篇 |
1986年 | 17篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 2篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1973年 | 4篇 |
1970年 | 2篇 |
排序方式: 共有1442条查询结果,搜索用时 15 毫秒
101.
Cubic magnetocrystalline anisotropy constant K1 as well as uniaxial anisotropy constant Ku and gyromagnetic ratio γ are precisely determined for (111) magnetic garnet epitaxial films from measurements on FMR field orientation dependence. Strict FMR conditions are derived from total free energy expressions, where the differences between magnetization direction and applied field direction are taken into consideration. By applying magnetic field in (110) plane, FMR is measured to obtain the three best fitting parameters of K1, Ku and γ. Present analysis is compared with Cronemeyer et al's analysis. Influence of sample misalignment on measurement accuracy is also presented. Similarly, for (110) garnet films with orthorhombic magnetic anisotropy, measurements are carried out for two crystallographic planes of (001) and (110), and the four best fitting parameters of K1, Ku, δ and γ are determined. 相似文献
102.
Iwaguchi S Suzuki M Sakai N Nakagawa Y Magee PT Suzuki T 《Yeast (Chichester, England)》2004,21(8):619-634
Electrophoretic karyotype studies have shown that clinical isolates of Candida albicans have extensive chromosome length polymorphisms. Chromosome translocation is one of the causes of karyotypic variation. Chromosome translocation events have been shown to occur very frequently at or near the major repeat sequence (MRS) on chromosomes. The MRS consists of the repeated sequences RB2, RPS and HOK, and the repeated sequences are considered to be the template for recombination. To investigate which element of the MRS is important for chromosome translocation, we constructed three cassettes, each containing a URA blaster and sequences homologous to one of the repeats, for insertion into the MRS region on the chromosomes. The ura3 strain STN22u2, which shows a stable, standard karyotype, was transformed with each construct. Insertion events with each cassette occurred at almost all chromosomes. Insertion into the RB2 repeat, but not into the RPS repeat, was accompanied by chromosome translocation in some transformants: chromosome translocations between chromosomes R and 7 and chromosomes 1 and 7 were found, as well as deletions of 7A and 7C from chromosome 7. We conclude that the insertion at the RB2 region may initiate chromosome translocation in C. albicans. 相似文献
103.
Diversity control in ant colony optimization 总被引:1,自引:0,他引:1
Optimization inspired by cooperative food retrieval in ants has been unexpectedly successful and has been known as ant colony
optimization (ACO) in recent years. One of the most important factors to improve the performance of the ACO algorithms is
the complex trade-off between intensification and diversification. This article investigates the effects of controlling the
diversity by adopting a simple mechanism for random selection in ACO. The results of computer experiments have shown that
it can generate better solutions stably for the traveling salesmen problem than ASrank which is known as one of the newest and best ACO algorithms by utilizing two types of diversity. 相似文献
104.
Maruyama T Shirota O Kawahara N Yokoyama K Makino Y Goda Y 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2003,44(1):44-48
'Magic mushrooms' (MMs) are psychoactive fungi containing the hallucinogenic compounds, psilocin (1) and psilocybin (2). Since June 6, 2002, these fungi have been regulated by the Narcotics and Psychotropics Control Law in Japan. Because there are many kinds of MMs and they are sold even as dry powders in local markets, it is very difficult to identify the original species of the MMs by morphological observation. Therefore, we investigated the internal transcribed spacer (ITS) region in the ribosomal RNA gene of MMs obtained in Japanese markets to classify them by a genetic approach. Based on the size and nucleotide sequence of the ITS region amplified by PCR, tested MMs were classified into 6 groups. Furthermore, a comparison of the DNA sequences of the MMs with those of authentic samples or with those found in the databases (GenBank, EMBL and DDBJ) made it possible to identify the species of tested MMs. Analysis by LC revealed that psilocin (1) was contained at the highest level in Panaeolus cyanescens among the MMs, but was absent in the Amanita species. 相似文献
105.
Hiromi?YoshidaEmail author Kyoko?Matsuda Yuki?Hirakawa Yoshiyuki?Mizushina 《Journal of the American Oil Chemists' Society》2003,80(7):665-674
To clarify the effects of microwave roasting on the distribution of tocopherols and FA of phospholipids within soybeans, whole
soybeans (Glycine max) were treated by microwave and further evaluted as compared to a raw sample. Tocopherol homologs, measured using HPLC, and
phospholipid profiles, quantified with GC, were determined in the seed coat, the embryonic axis, and selections of cotyledons
separated from three cultivars. The tocopherols were predominantly detected in the axis, followed by the cotyledons, and then
very little in the coat. As much as 25% of the individual tocopherols originally present in the coat were lost at 12 min of
roasting, whereas <25% was lost in the cotyledons and the axis after 20 min of roasting. The greatest rate of phospholipid
loss (P<0.05) was observed in PE, followed by PC and PI, and their changing patterns were more pronounced in the coat than in the
cotyledons or the axis. Thus, tocopherol content and phospholipid profiles change with microwave roasting according to tissue. 相似文献
106.
A new segment quantization method using the Lempel-Ziv algorithm is proposed, and it is applied to quantize line spectral frequency parameters in speech codec. The proposed segment quantizer can save four bits per frame, compared with the ITU-T G.729 speech codec (18 bits/frame), without degradation of subjective or objective speech quality 相似文献
107.
Y. Sekine Y. Tamura H. Yamaguchi Y. Yamakoshi J. Makino 《International Journal of Electrical Power & Energy Systems》1982,4(1):62-70
The present status of microprocessor applications in various fields of electric power systems is summarized. Special attention is directed towards development trends in the protection field where microprocessor applications are expected to cope with the increasingly stringent requirements for electric power supply reliability. Also discussed are the history, roles, design philosophy and basic schemes of microprocessor-based protective relaying systems. Only recently has their application reached a practical stage after long-term study and repeated field tests. 相似文献
108.
A new automatic cloud detection method to process the large data sets required for long-term trends in AVHRR time series images is described and tested over the Far East region. In the cloud detection method, a simple NDVI test was used to roughly separate land from ocean. After the NDVI test we carried out two tests: a visible or near-infrared test and an infrared test. Results from the cloud detection method over the Far East region are presented. In order to assess the cloud detection method, a comparison was carried out between the method presented and the Saunders and Kriebel daytime procedure using the N-Land database. We found that in general, the method presented has better performance than the Saunders and Kriebel procedure by about 0.5% to 10.5%. 相似文献
109.
Yusuke Kusuda Kinya Fukuda Masao Matsumura Kazuhisa Hagisawa Gaku Okamoto Tatsuo Nakanishi Yoshiyuki Inoue 《Electrical Engineering in Japan》2007,159(4):18-26
Recently, composite insulators have been increasingly employed mainly for economic reasons. We have developed a new type of outdoor termination using a composite insulator, which can be installed horizontally on a steel tower in order to reduce the construction cost. In this outdoor termination, SF6 gas is filled in the composite insulator and a cold shrinkable premolded rubber unit is applied instead of the combined use of a rubber‐molded stress relief cone, epoxy resin insulator and spring unit. The application of the composite insulator, SF6 gas and cold shrinkable premolded rubber unit reduces the total weight and makes it possible to install the termination horizontally on the tower. The new‐type outdoor termination for 77‐kV XLPE cable has already been applied in commercial use and enabled a reduction of the construction costs for power transmission lines. A 154‐kV new‐type outdoor termination has been developed and its initial electrical tests were successfully completed. This paper describes the design and performance of both 77‐kV and 154‐kV new‐type outdoor termination, and a follow‐up survey of the 77‐kV new termination in a commercial use. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(4): 18– 26, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20511 相似文献
110.
Takahiro Kawashima Tsuyoshi Kimura Takayuki Shibata Akio Kishida Takashi Mineta Eiji Makino 《Microelectronic Engineering》2010,87(5-8):704-707
In order to realize cellular network analysis on a chip-based system, our group has been developing a patterned cell culture microdevice with pillars in an array for tapping cells into space surrounded by the pillars. The pillar structures has advantages to trap both adhesive and non-adhesive cells and to precisely control positions of cells and distances between cells for understanding effects of various cell patterns on functions of a cellular network such as cell proliferation, differentiation, and network formation. In this paper, HeLa cell cultivation with the patterned cell culture microdevice having a pillar array fabricated by dry film of thick negative photoresist SU-8 on a glass substrate was executed as a feasibility study on a cellular network analysis. The results revealed that the device performance was found to be enough to culture HeLa cells for more than 48 h. In addition, relative extensibility of blocks of multiple cells compared with single cells tapped on the device was observed. Thus, the patterned cell culture microdevice proposed here could be applicable to analysis of cellular functions. 相似文献