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   370篇
  免费   5篇
电工技术   4篇
综合类   2篇
化学工业   60篇
金属工艺   14篇
机械仪表   5篇
建筑科学   38篇
矿业工程   2篇
能源动力   14篇
轻工业   15篇
水利工程   4篇
无线电   38篇
一般工业技术   58篇
冶金工业   92篇
原子能技术   2篇
自动化技术   27篇
  2023年   2篇
  2021年   4篇
  2020年   2篇
  2019年   2篇
  2018年   3篇
  2017年   3篇
  2016年   4篇
  2014年   2篇
  2013年   10篇
  2012年   7篇
  2011年   18篇
  2010年   8篇
  2009年   5篇
  2008年   16篇
  2007年   9篇
  2006年   12篇
  2005年   17篇
  2004年   13篇
  2003年   7篇
  2002年   10篇
  2001年   11篇
  2000年   5篇
  1999年   13篇
  1998年   27篇
  1997年   19篇
  1996年   12篇
  1995年   10篇
  1994年   7篇
  1993年   10篇
  1992年   2篇
  1991年   3篇
  1990年   4篇
  1989年   9篇
  1988年   5篇
  1987年   8篇
  1986年   9篇
  1985年   2篇
  1984年   6篇
  1983年   5篇
  1982年   7篇
  1981年   2篇
  1980年   8篇
  1979年   6篇
  1978年   6篇
  1977年   6篇
  1976年   7篇
  1975年   4篇
  1974年   2篇
  1970年   1篇
  1968年   2篇
排序方式: 共有375条查询结果,搜索用时 15 毫秒
41.
Conventional hernia repair is effective in terms of cure but is associated with considerable postoperative pain and delay in return to normal activity. Laparoscopic repair has the potential to reduce pain and speed return to normal activity, but there have been few published reports of the outcome of this operation in the UK. We present a prospective audit of 94 patients who underwent laparoscopic repair. Of the 94 patients, 87 (92.6%) were male and 7 (7.4%) were female. Thirteen of the repairs were bilateral and 12 were recurrent. Two had to be converted to open repair. The mean operating time for unilateral repair was 56 min and for bilateral repair 98 min. Sixty-three patients (67%) were discharged within 24 h and 21 (22.4%) were discharged within 48 h. There were minor complications in 20 patients (21%), eight of whom (8.5%) developed a haematoma. The other minor complications included seromas (2), bruising at the site of the entry port (2), hyperaesthesia in the groin (2), port hernia (1), shoulder tip pain after surgery (3) and postoperative urinary retention (2). Nine (9.5%) patients claimed to have had no pain or discomfort at all; 35 (37.2%) were pain and discomfort free in 2 weeks. Thirty-two (34%) patients returned to normal activities in 2 weeks. With a median follow-up of 8 months 3 (3.2%) recurrences were noted. It is emphasised that this series represents a learning curve and that the operation is developmental. We are now restricting laparoscopic repair to recurrent and bilateral hernias where the technique offers particular advantages.  相似文献   
42.
Many claims have been made about the benefits of a current-mode (CM) approach to IC design. The term is used to draw attention to some kind of special dependence on currents as signals, often without a clear orientation to the broader field, referring instead to recent CM papers. Its use suggests a significant and valuable distinction over “conventional” solutions, perhaps in the hope that this perspective, with an element of novelty at the cell level, will influence circuit design in the stringent context of IC production. This paper asks: What factors unambiguously define a current-mode circuit, and formally differentiate it from standard realizations of some function? Can one point to any compelling, and in the most favorable cases unique, advantages? Are these cells clearly of general value, capable of widespread utility? These issues are examined from the critical viewpoint that no circuits carry the entire functional burden by the exclusive use of either currents or voltages, and very few fully exploit the specific, but narrow, benefits of CM concepts. Real-world product development invariably demands the vigilant and full embrace of what might be called the Free Mode perspective, but merely as a mnemonic, not a classification.  相似文献   
43.
In 1985, Ontario Hydro decided to build a system control center and install an energy management system (EMS). Because hardware was being installed, it provided an opportunity to review the standards of performance demanded of the EMS and technological advances that could be utilized. As a result of this review, more rigorous reliability requirements were defined and a computer configuration designed to satisfy these requirements. The authors discuss the resulting performance standards, examine alternative architectures, and describe the computer architecture finally chosen for the EMS  相似文献   
44.
BACKGROUND: Recent data suggest that inhaled NO can inhibit platelet aggregation. This study investigates whether inhaled NO affects the expression level and avidity of platelet membrane receptors that mediate platelet adhesion and aggregation. METHODS AND RESULTS: In 30 healthy volunteers, platelet-rich plasma was incubated with an air/5% CO2 mixture containing 0, 100, 450, and 884 ppm inhaled NO. ADP- and collagen-induced platelet aggregation, the membrane expression of P-selectin, and the binding of fibrinogen to the platelet glycoprotein (GP) IIb/IIIa receptor were determined before (t0) and during the 240 minutes of incubation. In addition, eight patients suffering from severe adult respiratory distress syndrome (ARDS) were investigated before and 120 minutes after the beginning of administration of 10 ppm inhaled NO. In vitro, NO led to a dose-dependent inhibition of both ADP-induced (3+/-3% at 884 ppm versus 70+/-6% at 0 ppm after 240 minutes; P<.001) and collagen-induced (13+/-5% versus 62+/-5%; P<.01) platelet aggregation. Furthermore, P-selectin expression (36+/-7% of t0 value; P<.01) and fibrinogen binding (33+/-11%; P<.01) were inhibited. In patients with ARDS, after two who did not respond to NO inhalation with an improvement in oxygenation had been excluded, an increase in plasma cGMP, prolongation of in vitro bleeding time, and inhibition of platelet aggregation and P-selectin expression were observed, and fibrinogen binding was also inhibited (19+/-7% versus 30+/-8%; P<.05). CONCLUSIONS: NO-dependent inhibition of platelet aggregation may be caused by a decrease in fibrinogen binding to the platelet GP IIb/IIIa receptor.  相似文献   
45.
46.
Compared teacher ratings on the Behavior Problem Checklist of 56 adolescents who (a) were clinically diagnosed as schizophrenic (psychotic) and (b) had an adjustment reaction of adolescence (nonpsychotic). The schizophrenics tended to be rated as more deviant on both the flag items and Inadequacy–Immaturity dimensions of the checklist, whereas the adjustment reaction group was rated higher on the Conduct Problem and Socialized Delinquency dimensions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
47.
48.
Pattern recognition techniques and the statistics of directional data have been applied to a repetitive waveform to differentiate between subject categories. Normal subjects and Huntington's Chorea patients were distinguished by comparing the patterns in the summarized results of statistical tests applied to the Fourier harmonics of their contingent negative variation (CNV) responses, by the consecutive phase angle variations of the first harmonic of their CNV's, and by their different averaged CNV's. A logic algorithm which may provide the basis of computerized diagnosis, or even prediction of the condition, is described.  相似文献   
49.
PURPOSE: To evaluate the 10-year outcome of patients with invasive (T2-3N0M0, staged according to the tumor, node, metastasis system) bladder cancer who responded completely to a combination of methotrexate, vinblastine, adriamycin, and cisplatin (MVAC) chemotherapy followed by bladder-sparing surgery. PATIENTS AND METHODS: Of 111 surgical candidates who received neoadjuvant MVAC, 60 (54%) achieved a complete clinical response (T0) on transurethral resection (TUR) of the primary tumor site. Of these, 28 requested follow-up with TUR alone, 15 had a partial cystectomy, and 17 elected a radical cystectomy. The patients were followed up for a median of 10 years (range, 8 to 13 years). RESULTS: Of 43 patients who had bladder-sparing surgery, 32 (74%) are alive, which includes 25 (58%) with an intact functioning bladder. Twenty-four patients (56%) developed bladder tumor recurrences from 5 to 96 months, which were invasive in 13 (30%) and superficial in 11 (26%). Thirteen patients required a salvage cystectomy, of whom 6 died, which includes 4 (9%) from a new invasive neoplasm. Of the 17 patients who had radical cystectomy, 11 (65%) are alive. CONCLUSION: The majority of patients with invasive bladder tumors who achieve T0 status after neoadjuvant MVAC chemotherapy preserve their bladders for up to 10 years with bladder-sparing surgery. The bladder remains at risk for new invasive tumors. Cystectomy salvages the majority, but not all, of relapsing patients.  相似文献   
50.
Ophthalmopathy develops in about 30% of patients who have Graves' disease. The pathogenesis, like that of the hyperthyroidism, is probably autoimmune in nature. The eye manifestations are diverse and include lid lag, soft tissue swelling, proptosis, corneal damage, diplopia, and optic neuropathy. The natural history is benign in 90% of patients, with gradual improvement over time. Therapeutic options include corticosteroid therapy, radiation, and surgical treatment. The last is usually the therapy of choice for severe or disfiguring ophthalmopathy.  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