首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2649篇
  免费   77篇
  国内免费   8篇
电工技术   13篇
综合类   1篇
化学工业   296篇
金属工艺   12篇
机械仪表   33篇
建筑科学   19篇
矿业工程   2篇
能源动力   26篇
轻工业   128篇
水利工程   2篇
石油天然气   1篇
无线电   205篇
一般工业技术   247篇
冶金工业   1649篇
原子能技术   6篇
自动化技术   94篇
  2024年   2篇
  2023年   11篇
  2022年   21篇
  2021年   31篇
  2020年   15篇
  2019年   25篇
  2018年   34篇
  2017年   30篇
  2016年   32篇
  2015年   22篇
  2014年   41篇
  2013年   61篇
  2012年   55篇
  2011年   97篇
  2010年   56篇
  2009年   49篇
  2008年   65篇
  2007年   56篇
  2006年   48篇
  2005年   31篇
  2004年   28篇
  2003年   41篇
  2002年   37篇
  2001年   26篇
  2000年   36篇
  1999年   66篇
  1998年   519篇
  1997年   324篇
  1996年   212篇
  1995年   105篇
  1994年   84篇
  1993年   100篇
  1992年   16篇
  1991年   26篇
  1990年   23篇
  1989年   24篇
  1988年   27篇
  1987年   34篇
  1986年   20篇
  1985年   23篇
  1984年   5篇
  1982年   8篇
  1981年   15篇
  1980年   15篇
  1979年   3篇
  1978年   4篇
  1977年   31篇
  1976年   85篇
  1974年   7篇
  1973年   3篇
排序方式: 共有2734条查询结果,搜索用时 15 毫秒
1.
2.
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   
3.
4.
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.
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   
8.
9.
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   
10.
Socially amoral economic forces now drive health system change. The authors, assisted by a panel of experts on employers, health plans, providers, and consumers, discuss current drivers such as (1) employers' price-focused purchasing, without good quality/value measures; (2) health plans' growing successes and market clout; (3) providers declining prospects and fears about their future; and (4) consumers' worries about less choice. Future influences will include Medicare reforms, better information, and pro-consumer regulation of managed care, as well as rising social distress. The health system's future is now open for resolution in an evolving, imperfect market.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号