全文获取类型
收费全文 | 1201篇 |
免费 | 29篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 175篇 |
金属工艺 | 6篇 |
机械仪表 | 30篇 |
建筑科学 | 69篇 |
矿业工程 | 2篇 |
能源动力 | 25篇 |
轻工业 | 139篇 |
水利工程 | 11篇 |
石油天然气 | 9篇 |
无线电 | 68篇 |
一般工业技术 | 221篇 |
冶金工业 | 330篇 |
原子能技术 | 18篇 |
自动化技术 | 115篇 |
出版年
2023年 | 7篇 |
2021年 | 11篇 |
2020年 | 10篇 |
2019年 | 13篇 |
2018年 | 17篇 |
2017年 | 15篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 20篇 |
2013年 | 63篇 |
2012年 | 35篇 |
2011年 | 80篇 |
2010年 | 34篇 |
2009年 | 44篇 |
2008年 | 38篇 |
2007年 | 49篇 |
2006年 | 38篇 |
2005年 | 44篇 |
2004年 | 33篇 |
2003年 | 44篇 |
2002年 | 24篇 |
2001年 | 20篇 |
2000年 | 24篇 |
1999年 | 32篇 |
1998年 | 66篇 |
1997年 | 56篇 |
1996年 | 24篇 |
1995年 | 28篇 |
1994年 | 30篇 |
1993年 | 19篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 16篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 12篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 11篇 |
1977年 | 18篇 |
1976年 | 24篇 |
1975年 | 10篇 |
1974年 | 15篇 |
1973年 | 8篇 |
1972年 | 7篇 |
排序方式: 共有1233条查询结果,搜索用时 18 毫秒
1.
Online Raman spectra, obtained at different points along the spin line during pilot‐scale nonisothermal melt spinning of high density polyethylene (HDPE) fibers, are presented for the first time. The fraction of the crystalline phase corresponding to each spectrum was determined from the normalized integrated intensity of the 1418 cm?1 Raman band. It is well established that this band represents the orthorhombic crystalline phase in polyethylene. The estimates of percent crystallinity obtained from decomposition of the Raman spectrum were compared with the percent crystallinity from differential scanning calorimetry (DSC) measurements. It is concluded that online Raman spectroscopy can be successfully used to monitor the development of crystallinity in HDPE fibers as a function of distance from the spinneret. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 545–549, 2003 相似文献
2.
3.
J. M. Parpia W. P. Kirk P. S. Kobiela Z. Olejniczak 《Journal of Low Temperature Physics》1985,60(1-2):57-72
The ac susceptibility of lanthanum-diluted cerium magnesium nitrate has been compared to the temperature scales as derived
from the (P, T) relation determined by Halperin and that was measured recently by Greywall. It is found that the susceptibility does
not obey a simple Curie-Weiss law over the temperature range between 1 and 50 mK. The results of these calibrations are also
used to determine the temperatures for the second-order phase transitions into the superfluid phases of3He at several pressures. TheseT
c(P) values are compared to results of earlier experiments that used thermometry based on the susceptibility of platinum as well
as other thermometry techniques. 相似文献
4.
5.
6.
Excision of perianal fistulas using a 1.064 micron wavelength neodymium:yttrium aluminum garnet (ND:YAG) contact tipped laser with primary wound closure was used to treat 20 dogs with perianal fistulas. Overall, 19 of 20 (95%) dogs had resolution of fistulas after one or more ND:YAG treatments. The period of resolution ranged from 10 to 42 months with a mean of 22.9 months. Sixteen of 20 (80%) dogs had resolved fistulas after one laser excision. Three of the four recurrences underwent additional laser treatments with successful results. The total number of laser procedures ranged from one to three with a mean of 1.2 procedures. Postoperatively, anal tone as judged by digital rectal examination was reduced in about 60% of the cases, but clinical evidence of fecal incontinence only occurred in four of 20 cases. This was managed effectively with diet modification. The tendency toward loss of anal tone or fecal incontinence depended on the severity of preexisting anal stenosis. On a client survey, 19 of 20 owners believed that their animals experienced less pain during defecation after surgery and rated the results as excellent or good. The overall success rate using ND:YAG laser excision compared very favorably with previously reported studies of other methods of treatment for perianal fistulas in dogs. 相似文献
7.
8.
Scale and sludge from Bulalo geothermal field, Philippines, have been characterized by whole rock analysis, radioactivity counting, size analysis, light microscopy, scanning electron microscopy, and X-ray diffraction. Their leachability was assessed by regulatory leaching procedures and by sequential extraction. Both scale and sludge consisted mostly of oxides of Si, Al, and Fe with no radionuclides detected. The scale had 10% S content. Sulfides and silicates were important phases in both samples having size ranges from submicron to 2 mm. Geothermal soils at Bulalo have higher than normal soil levels of As, S, Cu, Cr, Zn, and Pb but regulatory leaching tests indicated that these elements are not released. However, the sequential extraction showed that As, Cu, and Zn were leachable under extreme conditions. 相似文献
9.
The crystallization behaviour of three amorphous alloys, Co50Ni25Si15B10, Ni50Co25Si15B10 and Ni50Co25P15B10, was studied by means of differential thermal analysis in conjunction with scanning transmission electron microscopy. Isochronal annealing showed a strong dependence of crystallization on scan rate over the range of 1.99 to 20.70 K min–1. At high Co/Ni ratios, a sequential two-stage crystallization process involving primary MS-I phase followed by MS-II phase precipitation was observed. At low Co/Ni ratios MS-I and MS-II crystallization were concurrent and inseparable. Replacement of the metalloid Si with P as the glass-former dramatically reduced the activation energy for crystallization as well as the crystallization temperature. A mechanistic understanding of these findings was pursued in light of TEM/STEM microanalysis 相似文献
10.
Nicole Ellison Rebecca Heino Jennifer Gibbs 《Journal of Computer-Mediated Communication》2006,11(2):415-441
This study investigates self-presentation strategies among online dating participants, exploring how participants manage their online presentation of self in order to accomplish the goal of finding a romantic partner. Thirty-four individuals active on a large online dating site participated in telephone interviews about their online dating experiences and perceptions. Qualitative data analysis suggests that participants attended to small cues online, mediated the tension between impression management pressures and the desire to present an authentic sense of self through tactics such as creating a profile that reflected their "ideal self," and attempted to establish the veracity of their identity claims. This study provides empirical support for Social Information Processing theory in a naturalistic context while offering insight into the complicated way in which "honesty" is enacted online. 相似文献