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   1485篇
  免费   0篇
  国内免费   1篇
综合类   2篇
化学工业   8篇
机械仪表   2篇
轻工业   49篇
无线电   2篇
一般工业技术   4篇
冶金工业   1415篇
自动化技术   4篇
  2021年   1篇
  2018年   1篇
  2012年   1篇
  2011年   3篇
  2010年   5篇
  2008年   1篇
  2007年   1篇
  2006年   1篇
  2005年   1篇
  2004年   1篇
  2003年   2篇
  2000年   1篇
  1999年   36篇
  1998年   453篇
  1997年   258篇
  1996年   145篇
  1995年   85篇
  1994年   80篇
  1993年   81篇
  1992年   15篇
  1991年   24篇
  1990年   21篇
  1989年   26篇
  1988年   23篇
  1987年   14篇
  1986年   20篇
  1985年   15篇
  1984年   1篇
  1983年   4篇
  1982年   7篇
  1981年   7篇
  1980年   14篇
  1979年   1篇
  1978年   2篇
  1977年   31篇
  1976年   97篇
  1975年   4篇
  1974年   1篇
  1971年   1篇
  1955年   1篇
排序方式: 共有1486条查询结果,搜索用时 15 毫秒
91.
The possibility of producing toxic effects in day-old chicks with mycotoxins from Phomopsis sp. or Diaporthe phaseolorum var. sojae isolates was studied. Evidence was found that Phomopsis sp., but not Diaporthe, produces hepatic necrosis with high mortality in chicks. Enzymatically, the hepatotoxin produced by Phomopsis sp. caused an increase in the level of liver glucose-6-P dehydrogenase. Mycotoxicosis caused by Phomopsis sp. was compared with lupinosis.  相似文献   
92.
93.
94.
The Depression Guideline Panel of the Agency for Health Care Policy and Research in 1993 published recommendations for treating major depression in primary care practice that were often based on studies of tertiary care psychiatric patients. We reviewed reports of randomized controlled trials in primary care settings published between 1992 and 1998. This evidence indicates that both antidepressant pharmacotherapy and time-limited depression-targeted psychotherapies are efficacious when transferred from psychiatric to primary care settings. In most cases, the choice between these treatments should depend on patient preference. Studies to date suggest that improving treatment of depression in primary care requires properly organized treatment programs, regular patient follow-up, monitoring of treatment adherence, and a prominent role for the mental health specialist as educator, consultant, and clinician for the more severely ill. Future research should focus on how guidelines are best implemented in routine practice, since conventional dissemination strategies have little impact.  相似文献   
95.
Examination of sister-chromatid exchanges (SCE) in lymphocytes may be useful for the evaluation of exposure to mutagens/carcinogens. Information of a possible association between SCE and cancer is scarce. We therefore examined SCE in peripheral lymphocytes in 131 women, aged 17-90 years (median 51.8 years), coming to operation because of a tumor of the breast. Venous blood samples were cultivated during PHA stimulation in the presence of BrdU. After treatment with colcemid (R), fixation, treatment with bisbenzimide and staining with Giemsa, 30 metaphases were scored in each specimen. 52 patients with peroperatively demonstrated carcinoma of the breast had 9.39 +/- 0.17 SCE/cell and the remaining 79 women with non-malignant fibroadenomatosis had 9.88 +/- 0.18 SCE/cell. By multiple regression analysis it appeared that the character of the tumor, the patient's age, hormone treatment and preoperative examination by mammography all were without significant influence on the SCE rate. A statistically significant correlation was found between SCE and cigarette smoking. THe 45 cigarette-smoking patients had 10.49 +/- 0.23 SCE/cell compared with 9.26 +/- 0.13 SCE/cell in the 86 non-smokers. It was concluded that spontaneous SCE in lymphocytes is not an indicator of carcinoma of the breast.  相似文献   
96.
97.
A review of all morphine classical conditioning studies performed since Pavlov reveals significant shifts in methodological and conceptual thinking during the past 7 decades. These shifts have tended to obscure the fact that a great deal of basic data are still needed before morphine classical conditioning can be understood. These data are needed to help clarify the relationship between drug conditioning and drug addiction. Recent evidence, for example, suggests that once morphine autonomic conditional reactions are established, they are highly resistant to extinction. The inclusion of these types of data in any conceptualization of drug dependency would appear to be of help in the formulation of new clinical approaches to this problem.  相似文献   
98.
Elevated circulating levels of immunoreactive parathyroid hormone (PTH), hypercalciuria and renal calculi were found in 3 patients with distal renal tubular acidosis (RTA). Treatment with alkali resulted in a fall of PTH toward normal and a reduction in urinary calcium, but the frequency of urolithiasis was unchanged. In one patient in whom prolonged follow-up was possible, a subtotal parathyroidectomy was performed. This was followed by virtual cessation of stone formation despite persistence of the acidification defect. This study suggests that RTA may be associated with secondary hyperparathyroidism and that the consequent elevation in PTH may play a contributory role in the pathogenesis of renal calculi.  相似文献   
99.
100.
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