全文获取类型
收费全文 | 4018篇 |
免费 | 117篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 241篇 |
综合类 | 3篇 |
化学工业 | 985篇 |
金属工艺 | 85篇 |
机械仪表 | 101篇 |
建筑科学 | 102篇 |
能源动力 | 154篇 |
轻工业 | 371篇 |
水利工程 | 14篇 |
石油天然气 | 2篇 |
无线电 | 317篇 |
一般工业技术 | 733篇 |
冶金工业 | 530篇 |
原子能技术 | 150篇 |
自动化技术 | 364篇 |
出版年
2023年 | 24篇 |
2022年 | 51篇 |
2021年 | 91篇 |
2020年 | 37篇 |
2019年 | 44篇 |
2018年 | 92篇 |
2017年 | 65篇 |
2016年 | 121篇 |
2015年 | 60篇 |
2014年 | 115篇 |
2013年 | 220篇 |
2012年 | 190篇 |
2011年 | 257篇 |
2010年 | 179篇 |
2009年 | 202篇 |
2008年 | 230篇 |
2007年 | 166篇 |
2006年 | 153篇 |
2005年 | 136篇 |
2004年 | 128篇 |
2003年 | 112篇 |
2002年 | 118篇 |
2001年 | 80篇 |
2000年 | 64篇 |
1999年 | 85篇 |
1998年 | 206篇 |
1997年 | 145篇 |
1996年 | 92篇 |
1995年 | 82篇 |
1994年 | 72篇 |
1993年 | 74篇 |
1992年 | 38篇 |
1991年 | 31篇 |
1990年 | 31篇 |
1989年 | 32篇 |
1988年 | 27篇 |
1987年 | 25篇 |
1986年 | 32篇 |
1985年 | 48篇 |
1984年 | 24篇 |
1983年 | 28篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 15篇 |
1978年 | 17篇 |
1977年 | 16篇 |
1976年 | 23篇 |
1975年 | 12篇 |
1974年 | 10篇 |
1973年 | 8篇 |
排序方式: 共有4152条查询结果,搜索用时 15 毫秒
11.
We show that the methodology based on the generalized inverse scattering transform (IST) concept provides a systematic way to discover the novel exactly integrable nonlinear Schrodinger equation models with varying dispersion, nonlinearity and gain or absorption. The fundamental innovation of the present approach is to notice that it is possible both to allow for a variable spectral parameter with new dependent variables and to apply of the famous "moving in time focuses" concept of the self-focusing theory to the IST formalism. We show that for nonlinear optics this algorithm is a useful tool to design novel dispersion managed fiber transmission lines and soliton lasers. Fundamental soliton management regimes are predicted 相似文献
12.
Y Hasegawa T Hasegawa K Fujii H Konii M Anzo T Aso S Koto M Takada Y Tsuchiya 《Canadian Metallurgical Quarterly》1997,82(1):156-158
A case of huge desmoid tumor successfully treated by hyperthermoradiotherapy is described. A 23-year-old man with familial adenomatous polyposis was operated upon for a desmoid tumor in the mesenterium involving the right kidney and small intestine in 1988. In 1990, the tumor recurred and could not be resected because of the involvement of the vena cava. The tumor grew larger and larger, and occupied two-thirds of the right lower quadrant. Several therapies using sulindac, tamoxifen, prednisolone, indomethacin, luteinizing hormone-releasing hormone analogue, and ascorbate were all ineffective. Finally, the combination of radiation and hyperthermia was used over a 6-month period. At the end of the hyperthermoradiotherapy, the tumor in the abdominal wall was markedly reduced in size, and the protruded abdominal wall became flat. To our best knowledge, this is the first report of the successful treatment of a huge desmoid tumor by hyperthermoradiotherapy. 相似文献
13.
Yamada T. Nakata Y. Hasegawa J. Amano N. Shibayama A. Sasago M. Matsuo N. Yabu T. Matsumoto S. Okada S. Inoue M. 《Solid-State Circuits, IEEE Journal of》1991,26(11):1506-1510
A 64-Mb dynamic RAM (DRAM) has been developed with a meshed power line (MPL) and a quasi-distributed sense-amplifier driver (qDSAD) scheme. It realizes high speed, t RAS=50 ns (typical) at V cc=3.3 V, and 16-b input/output (I/O). This MPL+qDSAD scheme can reduce sensing delay caused by the metal layer resistance. Furthermore, to suppress crosstalk noise, a V SS shield peripheral layout scheme has been introduced, which also widens power line widths. This 64-Mb DRAM was fabricated with 0.4-μm CMOS technology using KrF excimer laser lithography. A newly developed memory cell structure, the tunnel-shaped stacked-capacitor cell (TSSC), was adapted to this 64-Mb DRAM 相似文献
14.
T. Hasegawa M. Nantoh M. Ogino H. Sugawara M. Kawasaki H. Koinuma K. Kitazawa 《Journal of Superconductivity》1995,8(4):467-470
STM tunneling spectroscopy has been performed on the bulk single crystals of BiSrCaCuO (BSCCO) and the epitaxial thin films of YBaCuO (YBCO) at cryogenic temperatures. The STM images and tunneling spectra observed on the (001) surfaces can be classified into three cases; 1) Atomic image is visible. However, the tunneling spectrum shows semiconducting or smeared superconducting gap structures, depending on the tip-sample distance. 2) Clear atomic image can not be obtained. But, the tunneling spectrum shows flat bottom region with quite low zero bias conductance. 3) Tunneling spectra demonstrate gapless behavior, independent of the tip-sample separation. These observations support the quasi-2D electronic picture in whichs-wave like 2D superconducting layers are coupled with each other through the Josephson effect. 相似文献
15.
Hamada H. Hirano K. Goda N. Abe H. Hasegawa I. Okita Y. Arioka S. Niina T. 《Electronics letters》1994,30(20):1719-1720
The off state current for polysilicon thin-film transistors for pixels in LCDs has been successfully reduced by introducing a polysilicon buffer layer between a polysilicon active layer fabricated by solid-phase-crystallisation (SPC) and a fused quartz substrate. Off-slate current of less than 1 pA under Vgs=-25 V at Vds=3 V was obtained for n-channel single-gate coplanar transistors using the buffer layer (400 Å) 相似文献
16.
I Kobayashi M Hasegawa S Miyazaki M Nishida S Goto 《Canadian Metallurgical Quarterly》1993,67(6):528-534
Pseudomonas aeruginosa Nos. 1 and 5, each co-existing growth-inhibitor-producing and -nonproducing cells, were used in this study. An equal number of both cells (each 10(8) CFU/mouse) was challenged intraperitoneally to mice, and these cells in the heart blood and kidneys of mice were determined. Furthermore, the effect of piperacillin, ceftazidime and sisomicin on the cell distribution in mice was studied in the model infection due to P. aeruginosa Nos. 1 and 5. As a control experiment both cells of P. aeruginosa No. 1 were each challenged intraperitoneally at a dose of 10(8) CFU/mouse to mice of two groups, but there were no marked differences between the two types in cell counts of the heart blood or kidneys 9 hours after challenge. When a concomitant challenge of both cells (each 10(8) CFU/mouse) was performed in mice, the number of growth-inhibitor-producing cells of the heart blood and kidneys was about 100 times greater than that of the non-producing cells. These in vivo results were well comparable to the previous in vitro results and indicated that the inhibitor affected the invasion of the non-producing bacteria in the body in the model infection due to P. aeruginosa isolates consisting of the two types of cells. Similar results were obtained in mice with the model infection due to P. aeruginosa No. 5. Anti-pseudomonal drugs such as piperacillin (50 mg/mouse) and ceftazidime (50 mg/mouse) and sisomicin (1 mg/mouse) were given intramuscularly to mice infected concomitantly with both cells of P. aeruginosa No. 1.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
17.
The integral experiment on beryllium with D-T neutrons for verification of tritium breeding 总被引:1,自引:0,他引:1
Yury Verzilov Satoshi Sato Kentaro Ochiai Masayuki Wada Axel Klix Takeo Nishitani 《Fusion Engineering and Design》2007,82(1):1-9
A clean benchmark experiment on beryllium was performed with D-T neutrons at the FNS facility of the Japan Atomic Energy Agency. The main objective was to verify the integral data related to the tritium production on lithium isotopes. Tritium production rates, as well as activation reaction rates were measured inside the beryllium assembly that was shaped as a pseudo-cylindrical slab with an area-equivalent diameter of 628 mm and a thickness of 355 mm. Experimental results were analyzed with a three-dimensional Monte Carlo transport code MCNP-4C and FENDL/MC-2.0, JENDL-3.2/3.3 neutron transport libraries. Evaluation of reaction rates was based on the cross section data taken from the JENDL Dosimetry File and ENDF B-VI data libraries. Analysis shows that all calculation combinations (transport and activation cross section libraries) used for evaluation of reaction rates give data that is agreeable with measured values within 10%. 相似文献
18.
19.
20.
A comparison of monoacetyldiglycerides obtained from authentic phosphatidylcholines by acetolysis with those obtained by phospholipase C-acetylation was made to examine the intermolecular acyl migration, the intramolecular acyl migration between C-1 and C-2, and the formation of 1,3-isomer in the acetolysis reaction. Egg yolk phosphatidylcholine also was used. It was revealed that is acetolysis, the intermolecular acyl migration and selective degradation of polyunsaturated fatty acids did not take place at all. The intramolecular acyl migration, including the formation of 1,3-isomer, occurred to a small extent. Appreciable difference was not found in comparison of molecular species compositions of monoacetyldiglycerides derived by both methods from egg yolk phosphatidylcholine, except small differences found in the contents of two kinds of molecular species. 相似文献