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   218篇
  免费   6篇
  国内免费   7篇
电工技术   38篇
化学工业   3篇
金属工艺   5篇
机械仪表   3篇
建筑科学   2篇
矿业工程   1篇
轻工业   12篇
无线电   6篇
冶金工业   152篇
原子能技术   2篇
自动化技术   7篇
  2017年   1篇
  2016年   1篇
  2015年   3篇
  2014年   1篇
  2013年   8篇
  2012年   11篇
  2011年   6篇
  2010年   2篇
  2009年   6篇
  2008年   1篇
  2007年   3篇
  2005年   3篇
  2002年   3篇
  2001年   2篇
  1999年   12篇
  1998年   47篇
  1997年   27篇
  1996年   25篇
  1995年   9篇
  1994年   5篇
  1993年   10篇
  1992年   2篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1986年   3篇
  1985年   3篇
  1982年   1篇
  1981年   4篇
  1980年   1篇
  1979年   1篇
  1977年   4篇
  1976年   18篇
  1958年   1篇
  1955年   1篇
排序方式: 共有231条查询结果,搜索用时 406 毫秒
21.
Studied by endoscopy were 100 adolescents with diagnosed duodenal ulcer, as were 100 essentially healthy subjects and 90 ones of the same age presenting with primary chronic gastroduodenitis together with 60 adults who had duodenal ulcer. The following items were etiologic risk factors for duodenal ulcer, if combined, in the above adolescent series: Frequent episodes nervous of tension, hereditary predisposition and helicobacteriosis. In juveniles with duodenal ulcer, secretion and motility of the stomach appeared to be subjected to changes to a higher degree than it was in adult subjects with duodenal ulcer, while functions of the psychovegetative and immune systems were found to be less changeable in the former. In adolescents presenting with duodenal ulcer and primary chronic gastroduodenitis, the etiologic risk factors and pathogenetic changes were found out to be identical.  相似文献   
22.
23.
24.
BACKGROUND: The study was conducted to determine the influences of laparoscopy in the management and outcome of patients with appendicitis. METHODS: A retrospective analysis of 154 consecutive patients who were treated for suspected appendicitis. The pre-operative diagnosis included appendicitis, right lower quadrant pain of unknown etiology, and generalized peritonitis. RESULTS: Laparoscopy was used in 108 patients, including 70 laparoscopic appendectomies (LA) and 31 LAs converted to open appendectomy (OA). Forty-six patients had OA. The average operating time for LA was 74.3 minutes and 48.8 minutes with OA. Postoperative complications for LA (7%) included 1 trochar wound hemorrhage, 2 wound infections, and 2 intra-abdominal sepsis; and for OA (9%) were 1 post-operative intra-abdominal hemorrhage, 4 wound infections, 1 wound dehiscence, and 1 intra-abdominal sepsis. Post-operative stay for LA averaged 2.5 days and for OA averaged 4.5 days (P = .0049). LA patients had a considerably faster return to work and/or normal activity than OA patients (P = .00065). CONCLUSIONS: Laparoscopy influenced the management of 29% of patients presenting with suspected appendicitis. LA resulted in shorter hospitalization and a more rapid return to work and/or normal activity than OA.  相似文献   
25.
A cDNA encoding farnesyl diphosphate (FPP) synthase (FPPS) has been cloned from a cDNA library of Artemisia annua. The sequence analysis showed that the cDNA encoded a protein of 343 amino acid (aa) residues with a calculated molecular weight of 39420 kDa. The deduced aa sequence of the cDNA was highly similar to FPPS from other plants, yeast and mammals, and contained the two conserved domains found in polyprenyl synthases including FPPS, geranylgeranyl diphosphate synthases and hexaprenyl diphosphate synthases. The expression of the cDNA in Escherichia coli showed enzyme activity for FPPS in vitro.  相似文献   
26.
This study presented the outcome of 92 EOC patients treated by platinum or platinum analogue with cyclophosphamide from January 1, 1993 to December 31, 1995. There were 77 evaluable patients. The follow-up ranged from 4-42 months (median 14 months). The over all 3-year survival was 64 per cent and the median progression-free interval was 16 months for the whole group. There was no significant difference in survival between patients who received cisplatin and those who received carboplatin (P = 0.093). Patients who underwent optimal debulking surgery had significantly longer progression-free interval (P = 0.001) than those who had sub-optimal surgery. Fifty four per cent of patients with clear cell carcinoma died of the disease. Patients who received cisplatin had a drop out rate while on therapy more often (24% vs 5.3%) than that of carboplatin. Toxicities from chemotherapy were moderate but manageable.  相似文献   
27.
There is an early period of puberty in boys at the age of 10 to 13, accompanied by an increase in the level of follicle stimulating hormone and a low secretion of luteinizing hormone and testosterone, with no secondary sexual signs. The beginning of an increase in the luteinizing hormone and testosterone concentration in boys coincides with the development of secondary sexual signs. The stabilization of the level of luteinizing hormone takes place in boys already at the 2nd degree of the sexual development. The secretion of luteinizing hormone at this point corresponds already to the normal level in adult men. The level of testosterone in the blood continues to increase and does not reach its definitive level until after the age of 17, or at the 5th degree of sexual development. Like in boys, the increase of the follicle stimulating hormone in girls precedes the increase of the luteinizing hormone secretion. The beginning of the increase in the follicle stimulating hormone coincides with an increase in the level of estrogens and testosterone in the blood, and with the appearance of secondary signs of sexual maturation. The increase of the luteinizing hormone secretion takes place later in girls than in boys and is accompanied by a new and significant increase in the level of estrogens in the blood. At the 2nd degree of sexual development, the level of testosterone in the blood of girls is substantially higher than at the other stages.  相似文献   
28.
29.
30.
AIM: The study of the detection rate and potential pathogenetic significance of antibodies to low density oxidated lipoprotein (LDOL) in patients who had ischemic cerebral circulation disorder (ICCD) at young age. MATERIALS AND METHODS: The examination (enzyme immunoassay, general and neurological investigations, laboratory and instrumental tests) covered 148 patients who survived ICCD at young age (mean age 37.2 years). RESULTS: 48 of 108 (44%) patients had LDOL antibodies. Antibodies to cardiolipin, lupus anticoagulant were recorded in 33 (31%) patients. LDOL antibodies were higher and occurred more frequently in patients with Sneddon's syndrome (35% of patients, mean LDOL antibodies-44 units) and primary antiphospholipid syndrome (17% of patients, 45 units) than in atherosclerotic affection of the major head arteries (4%, 29 units) or occlusion of cerebral arteries of unclear genesis (8% of patients, 29 units). CONCLUSION: ICCD were not related to fast development of cerebral atherosclerosis or periaortitis due to production of LDOL antibodies as no relationships were found between their rise and atherosclerotic lesions of cerebral major arteries or periaortitis as shown by ultrasonic dopplerography or cerebral angiography. Feasibility of LDOL antibodies participation in the coagulation cascade and induction of hypercoagulatory condition causing ICCD needs special investigation.  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