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   3219篇
  免费   0篇
化学工业   16篇
金属工艺   4篇
建筑科学   2篇
矿业工程   2篇
能源动力   4篇
轻工业   5篇
无线电   1篇
一般工业技术   5篇
冶金工业   3171篇
原子能技术   1篇
自动化技术   8篇
  2020年   2篇
  2018年   1篇
  2015年   1篇
  2013年   2篇
  2012年   1篇
  2011年   2篇
  2010年   1篇
  2008年   1篇
  2006年   3篇
  2005年   2篇
  2004年   4篇
  2003年   4篇
  2000年   1篇
  1999年   70篇
  1998年   925篇
  1997年   538篇
  1996年   391篇
  1995年   235篇
  1994年   162篇
  1993年   185篇
  1992年   20篇
  1991年   34篇
  1990年   27篇
  1989年   29篇
  1988年   24篇
  1987年   19篇
  1986年   18篇
  1985年   19篇
  1983年   6篇
  1982年   19篇
  1981年   25篇
  1980年   33篇
  1979年   3篇
  1978年   10篇
  1977年   131篇
  1976年   258篇
  1975年   9篇
  1973年   1篇
  1965年   1篇
  1964年   1篇
  1954年   1篇
排序方式: 共有3219条查询结果,搜索用时 0 毫秒
51.
BACKGROUND: Growing interest in the replacement of synthetic food antioxidants by natural ones has fostered research on vegetable sources and screening of raw materials to identify new antioxidants. The food‐processing industry generates substantial quantities of phenolic‐rich by‐products that could be valuable natural sources of antioxidants. In this study the antioxidant properties and total phenolic, flavonoid and flavonol contents of three industrial by‐products, sugar beet pulp, sesame cake and potato peel, extracted with various solvents were examined. Since different antioxidant compounds have different mechanisms of action, several methods were used to assess the antioxidant efficacy of extracts. RESULTS: Among the six solvents tested, methanol gave the highest extract yield of potato peel and sugar beet pulp, while diethyl ether gave the highest extract yield of sesame cake. Methanol exhibited the highest extraction ability for phenolic compounds, with total phenolics amounting to 2.91, 1.79 and 0.81 mg gallic acid equivalent g?1 dry weight in potato peel, sugar beet pulp and sesame cake extracts respectively, and also showed the strongest antioxidant capacity in the three assays used. All three methods proved that potato peel extract had the highest antioxidant activity owing to its high content of phenolic compounds and flavonoids. CONCLUSION: On the basis of the results obtained, potato peel, sugar beet pulp and sesame cake extracts could serve as natural antioxidants owing to their significant antioxidant activity. Therefore they could be used as preservative ingredients in the food and/or pharmaceutical industries. Copyright © 2009 Society of Chemical Industry  相似文献   
52.
53.
54.
55.
56.
AIM: Analysis of cytostatic therapy effects on expression of gene MDR-1 in hemopoietic cells of patients with acute leukemia (AL) in complete clinicohematological remission (CCHR). MATERIALS AND METHODS: The study included 48 AL patients. 27 of them were untreated, 25 were resistant to or had recurrent AL. 4 patients were followed up. Bone marrow mononuclear fraction was investigated. Expression of MDR-1 gene in the cells was evaluated at hybridization. RESULTS: High expression of MDR-1 gene occurred in leukemic blast cells either upon achievement of CCHR or at least 6 months after its onset. When using schemes of chemotherapy containing two potential inductors of gene MDR-1, expression of this gene was registered significantly more frequently than in using schemes based on one inducing drug (p < 0.05). Frequency of occurrence of enhanced expression of gene MDR-1 in leukemic blasts significantly correlated with frequency of CCHR (p < 0.05). Correlation between occurrence of the gene's expression in normal hemopoietic cells in CCHR and occurrence of early AL recurrences was not found. CONCLUSION: The findings may facilitate design of new AL treatment programs.  相似文献   
57.
The paper presents 30-year experience in treating 158 patients with congenital cystic diseases of the liver and bile ducts. Depending on the pattern of hepatobiliary lesions, the diagnostic value of techniques, such as ultrasound, computerized tomography, scintigraphy of the liver duodenoscopy with THCG was defined. Analyzing the late outcomes provided recommendations for the most optimal surgical management: cystic fenestration and tunneling in hepatic polycystosis, pericystectomy in solitary cysts of the liver, different varieties of bile draining operations in choledochal cysts and Caroli's disease.  相似文献   
58.
In planimetric analysis of pneumoencephalograms the state of the brain ventricles can be assessed on the basis of planimetric coefficients--ratio of the sizes of individual parts of the ventricles and the width of the cerebral skull. Each of the calculated coefficients reflects the state of an individual portion of the ventricles. A summated coefficient Q is introduced which calculation permits to compose a digital characteristics of the state of the lateral ventricles as a whole. The ratio of the transverse size of the skull to the width of the III ventricle was also calculated, which reflects more objectively the state of the ventricle than the measurement of its absolute width value. The normal values of the coefficients were calculated on pneumoencephalograms with unchanged brain ventricles. In various degrees of ventricular dilatation the coefficients were determined on the pneumoencephalograms with a pathologically altered ventricular system.  相似文献   
59.
Estracyt (estramustine phosphate) injected intraperitoneally, 100 mg, per Kg. three days a week for four weeks, retarded growth of the R-3327 tumor in intact rats and in orchiectomized rats given androgen. The growth inhibition was accomplished by reduction of tumor deoxyribonucleic acid concentration and of the activities of acid phosphatase, leucine aminopeptidase, and other hydrolases. Histologic examination revealed cellular necrosis particularly prominent in the orchiectomized, androgen-treated rats. Estracyt did not affect the uptake of 65-Zn in the tumors but markedly reduced the high uptake in the dorsolateral prostate. There was no accumulation of 3H or 14C in the tumors after intravenous administration of 3H, 14C-labeled Estracyt, but the isotope concentrations decreased much in the same way as they decreased in the dorsolateral prostate. The isotopes were retained in the ventral prostate, where their concentrations were approximately twenty times higher than those in the muscle four hours after injection. The results demonstrate the value of the R-3327 tumor in the evaluation of drugs of potential clinical use for the treatment of prostatic cancer. The results also show that Estracyt has an antitumor effect which is not dependent on the antigonadotropic action of the drug.  相似文献   
60.
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