全文获取类型
收费全文 | 2200篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 93篇 |
金属工艺 | 3篇 |
机械仪表 | 33篇 |
建筑科学 | 26篇 |
矿业工程 | 5篇 |
能源动力 | 17篇 |
轻工业 | 78篇 |
水利工程 | 13篇 |
石油天然气 | 2篇 |
无线电 | 44篇 |
一般工业技术 | 120篇 |
冶金工业 | 1719篇 |
原子能技术 | 2篇 |
自动化技术 | 63篇 |
出版年
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 9篇 |
2014年 | 12篇 |
2013年 | 37篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 17篇 |
2009年 | 10篇 |
2008年 | 26篇 |
2007年 | 29篇 |
2006年 | 26篇 |
2005年 | 21篇 |
2004年 | 11篇 |
2003年 | 20篇 |
2002年 | 16篇 |
2001年 | 16篇 |
2000年 | 10篇 |
1999年 | 61篇 |
1998年 | 527篇 |
1997年 | 320篇 |
1996年 | 205篇 |
1995年 | 105篇 |
1994年 | 88篇 |
1993年 | 108篇 |
1992年 | 17篇 |
1991年 | 30篇 |
1990年 | 31篇 |
1989年 | 29篇 |
1988年 | 32篇 |
1987年 | 41篇 |
1986年 | 23篇 |
1985年 | 20篇 |
1983年 | 7篇 |
1982年 | 13篇 |
1981年 | 25篇 |
1980年 | 20篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 31篇 |
1976年 | 93篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1971年 | 3篇 |
1968年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有2220条查询结果,搜索用时 359 毫秒
1.
JJ Harris DK Lunt SB Smith WL Mies DS Hale M Koohmaraie JW Savell 《Canadian Metallurgical Quarterly》1997,75(4):986-992
Two groups of Brangus steers produced by nuclear transplantation cloning were used in parallel studies investigating the impact of calf- and yearling-feeding. The first group (n = 8) were fed as calves (CF; n = 4) or yearlings (YF; n = 4) to a constant age end point of 16 mo. The second group (n = 10) were fed as calves (CF; n = 5) or yearlings (YF; n = 5) to a constant live weight end point (530 kg). When slaughtered at the same age, CF and YF steers did not differ (P > .05) in feedlot ADG, but the CF steers were heavier and had higher dressing percentages, numeric yield grades, and quality grades (P < .05). Top loin steaks from the groups of steers did not differ (P > .05) in palatability traits. When fed to a constant live weight, the YF steers gained more rapidly (P < .05) and had lower (P < .05) numeric yield grades than did CF steers. Again CF steers had higher (P < .05) dressing percentages. There was no difference (P > .05) between the treatments in carcass quality grade or meat palatability characteristics. Thus, when finished to a constant weight end point, YF steers gained more rapidly, with no adverse effects on carcass quality grade or palatability traits; however, CF steers consistently produced higher dressing percentages, largely due to greater external fatness. 相似文献
2.
3.
4.
Effect of starting particle size on hot-pressing of magnesium oxide (MgO) powder was examined using seven kinds of MgO powders
prepared by a vapour-phase oxidation process; the average primary particle sizes were 11, 25, 32, 44, 57, 107 and 261 nm.
These compressed powders (compacts) were hot-pressed at a temperature between 900 and 1300°C. The densifications of these
compacts during the hot-pressing proceeded via (i) the sintering of primary particles within secondary particles and the rearrangement
of secondary particles/grains (900°C), (ii) the gradual grain growth controlled by the pore migration (900∼1100°C) and (iii)
the rapid grain growth due to the active mass transfer (1300°C); the grain sizes of MgO compacts hot-pressed at and below
1100°C were <1 μm, while those at 1300°C attained 20∼30 μm. The transluscent compact with the relative density of 99.7% could
be obtained when the compressed powder with the average primary particle size of 44 nm was hot-pressed at a temperature as
low as 1100°C for 1 h.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
5.
SB McNeil 《Canadian Metallurgical Quarterly》1997,23(3):287-8; discussion 289-90, 317
Jehovah's Witnesses refuse blood transfusions for themselves and for their children. This action can be difficult for health professionals to understand and can lead to tensions between the staff and family. For one family, their refusal of blood for their child lead to a greater understanding of their religion and its beliefs for those who cared for them. Interspersed with their story are the medical reasons their son required blood, the reasons Jehovah's Witnesses refuse blood transfusions, and what the acceptable alternatives are to Jehovah's Witnesses. This article will share the thoughts and feelings of the family and the nursing staff who cared for the family during this crisis. 相似文献
6.
7.
R. H. Howell P. A. Sterne M. J. Fluss J. H. Kaiser K. Kitazawa H. Kojima 《Journal of Superconductivity and Novel Magnetism》1994,7(1):169-173
High-statistics (>4 × 108 counts), room-temperature measurements of the electron-positron momentum density of La2?x Sr x CuO4 have been performed for samples with Sr concentrations of x=0.0, 0.1, 0.13, and 0.2. These spectra have been analyzed in conjunction with theoretical calculations of the electron-positron momentum density. The metallic samples show features consistent with the presence of a Fermi surface, but its evolution with increasing Sr concentration does not follow the predictions of band theory. These results may indicate the effects of electron-electron correlation on the electron momentum distribution in the Cu-O plane. 相似文献
8.
The majority of patients with soft tissue or bone sarcomas of the upper extremity can be treated today with limb-saving procedures using combined modality therapies. For patients with a tumor in the shoulder area, sometimes an interscapulothoracic amputation is the only radical surgical treatment. However, in selected cases, in which the tumor does not involve the neurovascular bundle, a limb-sparing alternative might be the Tikhoff-Linberg resection. Normal function of the hand and forearm, with reasonable function of the elbow, can be maintained by this procedure. Four case histories are reported. 相似文献
9.
10.
PURPOSE: To assess long-term survival following cladribine salvage treatment for previously treated patients with chronic lymphocytic leukemia. PATIENTS AND METHODS: Fifty-two patients aged 39-84 years with previously treated CLL received cladribine 0.12 mg/kg/day in 2-hour infusions for 5 days in monthly courses. Two-thirds were refractory to previous therapy, and 8 had prior fludarabine. RESULTS: Sixteen (31%) patients achieved complete response (CR) and 14 (27%) partial remission (PR) according to consensus criteria. Response correlated with clinical stage, number of previous treatment regimes, blood lymphocyte count, and lymphocyte halflife following the first cladribine course. Toxicity included pneumonia (n = 9), herpes zoster (n = 7), and septicemia (n = 2). Four patients in CR underwent high-dose chemotherapy with autologous blood stem cell support, and 2 remain in CR 48 and 60 months from start of cladribine, and 2 had relapse at 42 and 48 months, respectively. Median progression-free survival (Kaplan-Meier analysis) for CR patients was 23 months from start of cladribine treatment, and for PR patients 16 months. The projected overall survival was 80% at 3 years for CR patients, and the median survival 28 months for PR patients and 4 months for non-responding patients. CONCLUSIONS: Our previous finding of durable CRs from cladribine in advanced CLL is thus confirmed in a larger patient material, and follow-up indicate that long-term survival may be achieved. 相似文献