全文获取类型
收费全文 | 2349篇 |
免费 | 22篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 105篇 |
金属工艺 | 13篇 |
机械仪表 | 8篇 |
建筑科学 | 17篇 |
矿业工程 | 4篇 |
能源动力 | 11篇 |
轻工业 | 54篇 |
水利工程 | 2篇 |
无线电 | 46篇 |
一般工业技术 | 56篇 |
冶金工业 | 1980篇 |
原子能技术 | 2篇 |
自动化技术 | 68篇 |
出版年
2022年 | 6篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 14篇 |
2012年 | 19篇 |
2011年 | 26篇 |
2010年 | 28篇 |
2009年 | 15篇 |
2008年 | 13篇 |
2007年 | 12篇 |
2006年 | 15篇 |
2005年 | 23篇 |
2004年 | 23篇 |
2003年 | 18篇 |
2002年 | 10篇 |
2001年 | 10篇 |
2000年 | 15篇 |
1999年 | 65篇 |
1998年 | 640篇 |
1997年 | 334篇 |
1996年 | 247篇 |
1995年 | 112篇 |
1994年 | 102篇 |
1993年 | 116篇 |
1992年 | 15篇 |
1991年 | 25篇 |
1990年 | 28篇 |
1989年 | 41篇 |
1988年 | 36篇 |
1987年 | 21篇 |
1986年 | 28篇 |
1985年 | 35篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1981年 | 11篇 |
1980年 | 18篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 41篇 |
1976年 | 82篇 |
1975年 | 7篇 |
1973年 | 10篇 |
1972年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有2372条查询结果,搜索用时 15 毫秒
101.
102.
Although thoracoscopic sympathectomy or sympathicotomy is the best treatment for hyperhidrosis palmaris, a new approach of clipping only without transection of T2-sympathetic trunk is just as effective. Aside from the guaranteed cure of hyperhidrosis, this new method has fewer complications and has the advantage of recovery of the sympathetic tone in the hands if the procedure is reversed by the removal of the clips. Between March 18 and September 30 of 1996, 326 patients (190 female and 136 male with a mean age of 20.5 years) underwent thoracoscopic T2-sympathetic block by clipping to treat hyperhidrosis. Good results and few complications were noted during follow up six months to one year postoperatively. Five of the 326 patients, all female, had the operation reversed because of intolerable compensatory sweating. Three recovered from the compensatory sweating within two months and had less palmar sweating than before their sympathetic block; the fourth achieved relief of compensatory sweating after nine months, and the fifth reported no improvement. 相似文献
103.
The Beer-Lambert law has been used to determine the total attenuation coefficient, mu t, of three hard and three soft contact lens materials. The three hard contact lens materials were PMMA, Polycon II and Boston IV whereas the 3 soft materials were chosen with differing water contents of 38, 55 and 70%, respectively. The total attenuation coefficients of all six materials were obtained from measurements of the axial transmission at 632.8 nm of a series of plano powered lenses varying in axial thickness from 0.5 to 3.5 mm. The value of the total attenuation coefficient depends on both scattering and absorption and hence PMMA and Boston IV, which both incorporated a handling tint, showed significantly higher values (P < 0.0001) of mu t (0.562 +/- 0.010 mm-1 and 0.820 +/- 0.008 mm-1, respectively) than Polycon II (mu t = 0.025 +/- 0.005 mm-1). A comparison between Polycon II and the three hydrated soft contact lens materials showed a significant increase (P < 0.02) in the total attenuation coefficients for the 38% and 55% water content materials, and a weakly significant increase for the 70% water content soft lens material (P < 0.1). On the assumption that the absorption coefficients of these four materials are approximately constant, then this change would be due to an increase in the scattering coefficient of the material and could contribute to an increase in intraocular scatter. No significant difference (P > 0.5) was found between any of the hydrated soft contact lens materials tested. 相似文献
104.
AC Hammond CC Chase EJ Bowers TA Olson RD Randel 《Canadian Metallurgical Quarterly》1998,76(6):1568-1577
We investigated heat tolerance and growth rate in two trials under ambient conditions in central Florida. Trial 1 (1994) involved 38 Brahman (B), 21 Senepol (S), 19 B x Angus (A), 20 S x A, and 20 Tuli (T) x A heifers. Trial 2 (1995) involved 13 A, 35 B, 30 S, 23 B x A, 17 S x A, and 28 T x A heifers. Measurements were made on three consecutive weeks during the hotter and cooler seasons of each year and included rectal temperature (RT, degrees C), respiration rate (RR, bpm), temperament score (TS; 1 = very docile, 5 = very aggressive), blood packed-cell volume (PCV), and plasma cortisol concentration (CORT). Data for RT were transformed (log10 [RT - 37]) before analysis. On the hottest date in Trial 1, log10 RT was not different between B (.39 +/- .011) and B x A (.37 +/- .016) or between T x A (.35 +/- .015) and B x A, but log10 RT was lower (P < .05) in S x A (.30 +/- .015) than in either S (.35 +/- .015) or T x A. On all dates in Trial 1, RR was lower (P < .05 to .001) and PCV was higher (P < .05 to .001) in B than in B x A. There were few differences in TS except on two dates when B scored higher (P < .01 to .001) than B x A, and these differences were associated with higher (P < .05) CORT in B than in B x A. Using initial BW as a covariate, adjusted ADG (kg) of T x A (.52 +/- .023) was not different from adjusted ADG of B x A (.57 +/- .024) or S x A (.54 +/- .023). On the hottest date in Trial 2, log10 RT and RR were higher (P < .001) in A (.59 +/- .017, 74 +/- 2.7) than in B (.47 +/- .010, 39 +/- 1.6), S (.42 +/- .011, 50 +/- 1.8), and crossbred heifers (.47 +/- .011, 60 +/- 1.8; .43 +/- .014, 55 +/- 2.4; and .50 +/- .012, 48 +/- 2.0 for T x A, S x A and B x A, respectively), and RR was higher (P < .001) in B x A than in B. On the coolest date in Trial 2, RR was slightly lower in B (32 +/- .5) than in A(34 +/- .7, P < .01) and B x A (36 +/- .6, P < .001) and was associated with higher PCV in B than in A. On both dates, TS and CORT were higher (P < .01) in B than in A. In Trial 2, adjusted ADG (kg) was higher (P < .01) in B (.43 +/- .017) than in A (.32 +/- .033), higher (P < .001) in S (.45 +/- .018) than in A, and higher (P < .001) in crossbreds (B x A [.53 +/- .023] + S x A [.44 +/- .025] + T x A [.46 +/- .019]) than in A. These data indicate that heat tolerance in F1 crosses of tropically adapted breeds (Tuli, Senepol, Brahman) with a temperate breed (Angus) is similar to heat tolerance displayed by purebred tropical breeds (Senepol, Brahman). 相似文献
105.
FC Wei HC Chen CC Chuang SH Chen 《Canadian Metallurgical Quarterly》1994,93(2):345-51; discussion 352-7
Microsurgical toe transfer is an established method for reconstruction of missing thumbs. However, there is little agreement on which of the various techniques represents the ideal transfer. Basically, selection of technique requires balancing the patient's functional needs, appearance of the reconstructed thumb, and donor-site cosmesis. Based on our experience with 103 toe-to-thumb transfers performed over the past 9 years, this paper attempts to provide guidelines for appropriate selection among the four most commonly employed toe transfer techniques (e.g., second toe, total great toe, great toe wrap-around, trimmed great toe) so that optimal results and patient's acceptance can both be achieved. 相似文献
106.
107.
108.
Three elderly patients have recently been admitted as emergencies to the Infection Unit of the Aberdeen Hospitals as presumed cases of infective gastro-enteritis. Investigation revealed the presence of a villous papilloma of the rectum in each case. 相似文献
109.
110.