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   1302篇
  免费   1篇
化学工业   17篇
金属工艺   3篇
机械仪表   4篇
建筑科学   4篇
矿业工程   1篇
轻工业   2篇
水利工程   1篇
石油天然气   3篇
无线电   2篇
一般工业技术   7篇
冶金工业   1251篇
自动化技术   8篇
  2023年   1篇
  2022年   3篇
  2021年   2篇
  2018年   2篇
  2017年   4篇
  2016年   2篇
  2015年   4篇
  2014年   1篇
  2013年   5篇
  2010年   1篇
  2009年   1篇
  2006年   2篇
  2005年   2篇
  2004年   2篇
  2003年   3篇
  2002年   2篇
  2001年   2篇
  1999年   37篇
  1998年   318篇
  1997年   192篇
  1996年   151篇
  1995年   97篇
  1994年   68篇
  1993年   75篇
  1992年   13篇
  1991年   28篇
  1990年   27篇
  1989年   24篇
  1988年   26篇
  1987年   17篇
  1986年   10篇
  1985年   11篇
  1984年   1篇
  1983年   5篇
  1982年   6篇
  1981年   10篇
  1980年   12篇
  1978年   7篇
  1977年   41篇
  1976年   80篇
  1975年   4篇
  1973年   1篇
  1972年   1篇
  1969年   1篇
  1967年   1篇
排序方式: 共有1303条查询结果,搜索用时 250 毫秒
101.
102.
103.
104.
The effects of age and gender on the single dose pharmacokinetics of avitriptan and its three metabolites were assessed in 15 young men, 15 young women, 15 elderly men and 15 elderly women. Avitriptan was administered as a 150-mg capsule after a 10-hour fast and serial plasma and urine samples were collected up to 36 hours after the dose. Plasma samples were analyzed for avitriptan and its metabolites, N-desmethyl avitriptan (ND048), O-desmethyl avitriptan (OD048), and methoxypyrimidinyl piperazine (MPP). Urine samples were analyzed for only avitriptan and MPP. Avitriptan was well tolerated in all four groups. The drug was rapidly absorbed with a median time to maximum plasma concentration (tmax) between 0.5 and 1.5 hours. No significant gender-related differences were found in the maximum plasma concentration (Cmax) and area under the concentration-time curve extrapolated to infinity (AUC0-infinity) of avitriptan. Renal clearance of avitriptan was significantly smaller in young women compared with young men, but this is clinically not relevant because only 2% to 3% of the total dose is excreted unchanged. Compared with the young volunteers, mean Cmax was approximately 50% higher in the elderly but there was no difference in the AUC0-infinity between the 2 age groups. Plasma concentrations of ND048, OD048, and MPP were each 50 to 100 fold lower than those of avitriptan. Hence some age- and gender-related differences found in the pharmacokinetics of avitriptan metabolites are probably not relevant in the assessment of overall safety and efficacy of avitriptan. Based on the pharmacokinetics and tolerability, no age or gender-related dose adjustment is necessary for avitriptan.  相似文献   
105.
106.
The authors suggest that apitherapy should be used in the treatment of patients with chronic non-specific pulmonary diseases (ChNPD) in order that it might be more effective. Apitherapeutic complex (bee venom and bee keeping apiculture produce) has been applied to the treatment of 104 ChNPD patients. High effectiveness of apitherapy in a combined treatment of ChNPD patients was demonstrated as was their stimulating and normalizing influence on the function of the adrenals.  相似文献   
107.
Perfluorochemical or perfluorocarbon liquids have an enormous gas-carrying capacity. During tidal liquid ventilation the respiratory medium of both functional residual capacity and tidal volume is replaced by neat perfluorocarbon liquid. Tidal liquid ventilation is characterized by convective and diffusive limitations, but offers the advantage of preserved functional residual capacity, high compliance and improved ventilation-perfusion matching. During partial liquid ventilation only the functional residual capacity is replaced by perfluorocarbon liquid. Both tidal and partial liquid ventilation improve gas exchange and lung mechanics in hyaline membrane disease, adult respiratory distress models and meconium aspiration. Compared to gas ventilation, there is less histologic evidence of barotrauma after liquid ventilation. Cardio-pulmonary interaction, inherent to the high density of liquid, and long term safety need further study. However, extrapolating from animal data, and taking into account promising human pilot studies, liquid ventilation has the desired properties to occupy an important place in the therapy of restrictive lung disease in man.  相似文献   
108.
BACKGROUND: Signals from the B-cell antigen receptor (BCR) help to determine B-cell fate, directing either proliferation, differentiation, or growth arrest/apoptosis. The protein tyrosine phosphatase SHP-1 is known to regulate the strength of BCR signaling. Although the B-cell co-receptor CD22 binds SHP-1, B cells in CD22-deficient mice are much less severely affected than those in SHP-1-deficient mice, suggesting that SHP-1 may also regulate B-cell signaling by affecting other signaling molecules. Moreover, direct substrates of SHP-1 have not been identified in any B-cell signaling pathway. RESULTS: We identified the B-cell transmembrane protein CD72 as a new SHP-1 binding protein and as an in vivo substrate of SHP-1 in B cells. We also defined the binding sites for SHP-1 and the adaptor protein Grb2 on CD72. Tyrosine phosphorylation of CD72 correlated strongly with BCR-induced growth arrest/apoptosis in B-cell lines and in primary B cells. Preligation of CD72 attenuated BCR-induced growth arrest/death signals in immature and mature B cells or B-cell lines, whereas preligation of CD22 enhanced BCR-induced growth arrest/apoptosis. CONCLUSIONS: We have identified CD72 as the first clear in vivo substrate of SHP-1 in B cells. Our results suggest that tyrosine-phosphorylated CD72 may transmit signals for BCR-induced apoptosis. By dephosphorylation CD72. SHP-1 may have a positive role in B-cell signaling. These results have potentially important implications for the involvement of CD72 and SHP-1 in B-cell development and autoimmunity.  相似文献   
109.
110.
1. Tammar Wallaby embryonic blood has been shown to have three alpha-like and two beta-like globin chains in its four haemoglobin components and partial sequences of several chains have been determined. 2. The major embryonic beta-like chain (epsilon) is similar to other mammalian embryonic beta-like chains on the basis of sequencing its first 60 amino acids. 3. There is another embryonic beta-like chain present in one haemoglobin component. It was designated omega and, in its first 54 amino acids, it has features that are more like avian globins than mammalian globins. 4. The one alpha-like embryonic globin sequenced has mammalian rather than avian characteristics. 5. A provisional phylogenetic tree of beta-like globins has been determined. The Tammar epsilon-globin forms a monophyletic group with marsupial and other mammalian embryonic globins; the omega-globin forms a monophyletic group with bird adult and embryonic globins.  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