全文获取类型
收费全文 | 3147篇 |
免费 | 30篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 80篇 |
化学工业 | 334篇 |
金属工艺 | 1563篇 |
机械仪表 | 30篇 |
建筑科学 | 15篇 |
矿业工程 | 1篇 |
能源动力 | 47篇 |
轻工业 | 64篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 249篇 |
一般工业技术 | 239篇 |
冶金工业 | 430篇 |
原子能技术 | 42篇 |
自动化技术 | 81篇 |
出版年
2023年 | 6篇 |
2022年 | 17篇 |
2021年 | 14篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 26篇 |
2015年 | 11篇 |
2014年 | 32篇 |
2013年 | 99篇 |
2012年 | 84篇 |
2011年 | 81篇 |
2010年 | 54篇 |
2009年 | 90篇 |
2008年 | 107篇 |
2007年 | 94篇 |
2006年 | 93篇 |
2005年 | 75篇 |
2004年 | 66篇 |
2003年 | 98篇 |
2002年 | 120篇 |
2001年 | 124篇 |
2000年 | 94篇 |
1999年 | 121篇 |
1998年 | 242篇 |
1997年 | 207篇 |
1996年 | 157篇 |
1995年 | 99篇 |
1994年 | 102篇 |
1993年 | 158篇 |
1992年 | 151篇 |
1991年 | 135篇 |
1990年 | 50篇 |
1989年 | 38篇 |
1988年 | 30篇 |
1987年 | 29篇 |
1986年 | 36篇 |
1985年 | 31篇 |
1984年 | 40篇 |
1983年 | 23篇 |
1982年 | 13篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1976年 | 15篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 5篇 |
排序方式: 共有3178条查询结果,搜索用时 0 毫秒
31.
32.
We observed change in distance between two droplets in each step after application of large multi-step shear strains. Experiments were performed using a sliding plate apparatus. Large step shear strains were applied to two polyisobutylene droplets in poly(dimethyl siloxane) matrix in the same plane between the plates. The distance between the two droplets decreases with increasing the total shear strain, which is given by the product of the step strain magnitude and the number of application of the step strains. The two droplets coalesce when the distance becomes less than the diameter of the droplets. The slope for plots of the distance versus the total strain is independent of the step strain magnitude. This indicates that the effect per unit strain on the distance is the same, irrespective of the strain magnitude. It is suggested that a stronger hydrodynamic interaction between the droplets is the main cause for the droplet approach. 相似文献
33.
K Tarao H Hoshino A Shimizu S Ohkawa M Harada Y Nakamura Y Ito S Tamai N Okamoto 《Canadian Metallurgical Quarterly》1995,75(6):1255-1262
BACKGROUND: The relationship between echosonographic patterns of patients with cirrhosis who are antihepatitis C virus (HCV)-positive, the DNA synthesis of hepatocytes, and the risk for HCC were studied. METHODS: Thirty-eight patients with anti-C-100 antibody-positive and Child's grade A posthepatitic cirrhosis were studied. DNA synthesis activity was measured by a bromodeoxyuridine (BrdU, a thymidine analogue)-labeling index (LI), using the BrdU-anti-BrdU in vitro method, and the patients were followed prospectively by frequent liver ultrasonography for 3 years. The ultrasound patterns were classified into fine, coarse, and coarse-nodular (CN) patterns, and the reproducibility of the classification in practical use also was confirmed. RESULTS: Of the 21 patients with high DNA synthesizing cirrhosis (BrdU LI > or = 1.5%), 10 (48%) showed coarse-nodular, 5 (24%) coarse, and 6 (29%) fine pattern in ultrasonography. Conversely, of the 17 patients with low DNA synthesizing LC (BrdU LI < 1.5%), only 1 (6%) showed coarse-nodular, 2 (12%) coarse, and 14 (82%) fine pattern. A significant relationship was found between the two groups of BrdU LI and ultrasound imaging patterns (P < 0.05). The incidence of CN pattern was significantly higher (P < 0.01) in the high DNA synthesizing group than in low DNA synthesizing group. Of the 11 patients with CN pattern by ultrasound imaging, 10 (91%) were in the high DNA synthesizing group, and 9 (82%) developed HCC during the follow-up period, compared with 3 of 7 (43%) with coarse, and only one of 20 (5%) with fine pattern developed HCC. The incidence of HCC was significantly higher (P < 0.01) in patients with a CN cirrhosis pattern than in those with a fine pattern. CONCLUSIONS: In patients with cirrhosis who are anti-HCV-positive, the CN pattern by ultrasound imaging indicates increased DNA synthesis of hepatocytes and a high risk for developing HCC. 相似文献
34.
H. Okamoto 《Journal of Phase Equilibria and Diffusion》1992,13(6):679-681
35.
H. Okamoto 《Journal of Phase Equilibria and Diffusion》1996,17(2):166-167
36.
37.
38.
39.
We have measured the quenching rate of the Na 3P level and the doublet mixing rates of the Na 3P(3/2) and 3P(1/2) levels in a propane-air flame at atmospheric pressure. To obtain these rates, subnanosecond time-resolved fluorescence measurements were made using a mode-locked dye laser and the time-correlated single-photon counting method. Our results are 1.4 x 10(9) s(-1) for the quenching rate and 3.0 x 10(9) s(-1) for the 3P(3/2) --> 3P(1/2) mixing rate. 相似文献
40.
W. R. Vogler A. C. Olson S. Okamoto M. Shoji R. L. Raynor J. F. Kuo W. E. Berdel H. Eibl J. Hajdu H. Nomura 《Lipids》1991,26(12):1418-1423
Alkyl lysophospholipids have been shown to be cytooxic to a number of neoplastic tissues. One, ET-18-OCH3, has been used to selectively purge leukemic cells from mixtures with normal marrow progenitor cells,in vitro andin vivo. We have measured the 50% inhibitory (IC50) effect of a series of ether, lipids (EL) on leukemic cells (HL60, K562, Daudi, KG-1, KG-1a) and normal marrow progenitor
cells. Cells were incubated with varying concentrations of EL for 4 hr and assayed for viability, [3H]thymidine incorporation and clonogenicity in semi-solid media. The effect on protein kinase C (PKC) activity was assayed
for each compound. Compounds tested included three glycerophosphocholine analogs-ET-18-OCH3, ET-16-NHCOCH3, and BM 41.440. In addition, a lipoidal amine, CP 46665, an ethyleneglycolphospholipid, AEPL, and four single chain alkylphosphocholine
analogs, HePC2, HePC3, HePC4 and HePC6 were also tested. During the period of incubation, the cells remained viable (>70%) as judged by trypan blue dye exclusion.
The glycerophosphocholines were the most active and showed the highest therapeutic index. The lipoidal amine was active, but
toxic to normal marrow progenitor cells. The ethyleneglycolphospholipid was active against HL60, but not against the other
cell lines. The single chain alkylphosphocholine analogs were less active. All of the compounds inhibited PKC activity; however,
the glycerophosphocholines were the most inhibitory.
Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl
Ether Lipids, Tokyo, Japan, May 1989. 相似文献