全文获取类型
收费全文 | 1138篇 |
免费 | 12篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 15篇 |
技术理论 | 1篇 |
综合类 | 16篇 |
化学工业 | 34篇 |
金属工艺 | 2篇 |
机械仪表 | 4篇 |
建筑科学 | 13篇 |
矿业工程 | 2篇 |
能源动力 | 7篇 |
轻工业 | 8篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
武器工业 | 4篇 |
无线电 | 41篇 |
一般工业技术 | 44篇 |
冶金工业 | 946篇 |
自动化技术 | 13篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 10篇 |
2011年 | 13篇 |
2010年 | 22篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 25篇 |
2006年 | 11篇 |
2005年 | 10篇 |
2004年 | 8篇 |
2003年 | 5篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 23篇 |
1998年 | 255篇 |
1997年 | 161篇 |
1996年 | 94篇 |
1995年 | 63篇 |
1994年 | 54篇 |
1993年 | 61篇 |
1992年 | 3篇 |
1991年 | 24篇 |
1990年 | 11篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 15篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 29篇 |
1976年 | 82篇 |
1975年 | 3篇 |
排序方式: 共有1153条查询结果,搜索用时 15 毫秒
81.
The clinical consequences of single or multiple exposure of pregnant gilts to porcine reproductive and respiratory syndrome virus (PRRSV) at various stages of gestation were determined. Thirty-three pregnant gilts were allotted to 6 experimental groups (5 to 7 gilts/group). Gilts of groups 1 to 5 were exposed to strain NADC-8 of PRRSV at the following times: group 1, gestation day (GD) 1; group 2, GDs 1 and 90; group 3, GD 30; group 4, GDs 30 and 90; group 5, GD 90. Virus exposure was by either intrauterine (GD 1) or oronasal (GDs 30 and 90) inoculation. Gilts of group 6 were kept as nonexposed controls. Gilts were either necropsied on or about GD 111 (groups 1 to 5) or were allowed to farrow (group 6). The detection of PRRSV in serum of fetuses and piglets (within 12 hof birth) was considered evidence of transplacental infection. Transplacental infection and virus-induced death were and were not confirmed for groups 3, 4, and 5 and for groups 1, 2, and 6, respectively. Collectively, the results indicated that intrauterine exposure to PRRSV at GD 1 was without clinical effect (groups 1 and 2) and provided protection against subsequent exposure to the same strain of virus at GD 90 (group 2). The highest incidence of transplacental infection and fetal death followed a single exposure to PRRSV at GD 90 (group 5). 相似文献
82.
Analysis of amino acids is complicated by treatment with ampicillin. High voltage electrophoresis, which is convenient for the qualitative assessment of metabolic diseases, yields smears of ampicillin that mask the bands of citrulline, homocitrulline, phenylalanine, cystine, and homocystine. The addition of penicillinase prior to high voltage electrophoresis eliminates ampicillin and other penicillins and reveals these key amino acids. 相似文献
83.
OBJECTIVE: To report a case of probable famotidine-induced mixed hepatocellular jaundice. CASE SUMMARY: A 55-year-old man presented with a one-month history of mid-epigastric pain. Initial physical examination and laboratory studies, including liver enzyme concentration tests, were unrevealing. A diagnosis of gastritis was made and ranitidine was prescribed. Following one week of therapy, the patient's symptoms had not improved and therapy was changed to famotidine and sucralfate. Approximately one week later the patient presented with jaundice. Liver enzyme concentrations were elevated and the patient was hospitalized for further evaluation. Five days following discontinuation of famotidine, liver enzyme concentrations were normal and jaundice had resolved. Further tests did not reveal any pathologic etiology. DISCUSSION: Hepatic changes have occurred in patients receiving histamine2-antagonists; ranitidine and cimetidine have been cited most frequently. In general, the elevations are mild, transient, and return to baseline with continued therapy. This is one of the first case reports of probable famotidine-induced mixed hepatocellular jaundice. CONCLUSIONS: There was a temporal relationship between the patient's signs and symptoms and initiation of famotidine. No identifiable factors contributed to the elevated liver enzyme concentrations and jaundice. 相似文献
84.
85.
WL Luken 《Canadian Metallurgical Quarterly》1986,33(2):1424-1425
86.
LC Pronk WL van Putten V van Beurden M de Boer-Dennert G Stoter J Verweij 《Canadian Metallurgical Quarterly》1999,43(2):173-177
PURPOSE: Fluid retention, which includes peripheral edema, ascites, pleural or pericardial effusion, or a combination of these that is sometimes associated with significant weight gain, is one of the most troublesome cumulative side effects of docetaxel. A suggestive observation from the data base available at the manufacturer (Rhone-Poulenc Rorer) was that patients who received venotonic drugs appeared to tolerate more courses of docetaxel. This prompted a comparative study to investigate whether the venotonic drug hydroxyethylrutosiden could reduce or delay docetaxel-related fluid retention. METHODS: A total of 85 patients with metastatic breast cancer who were treated with docetaxel at a dose of 100 mg/m2 with corticoid comedication were allocated to receive either 300 mg hydroxyethylrutosiden given orally four times daily (group A) or no hydroxyethylrutosiden (group B). The end point for analysis was the development of fluid retention of > or = grade 2. RESULTS: Fluid retention of > or = grade 2 was reported in 14 of 42 patients (33%) in group A and in 15 of 43 patients (35%) in group B and occurred after a median of 4 cycles of docetaxel in both groups. Weight gain was similar in groups A and B. CONCLUSION: We conclude that hydroxyethylrutosiden does not reduce or delay the incidence and severity of docetaxel-related fluid retention. 相似文献
87.
Dendritic textured Nb3Si thin films, deposited by sputtering pure niobium onto silicon substrates, exhibit a rather high zero-resistance critical temperature, Tc. X-ray and TEM measurements reveal the films to be polycrystalline with the A15 phase. The resistance begins to drop sharply at a temperature of 13.3 K and down to zero at 11.9 K without residual resistivity. 相似文献
88.
89.
90.
The static performance of finite journal bearings lubricated with non-Newtonian power law fluids is analyzed by using a control volume method with an Elrod algorithm to solve the average Reynolds equation and determine the cavitation region accurately. The results show that the flow behavior index of power law fluids has an insignificant affect on the load ratios, side flow ratios and cavitation regions, while it significantly affects load capacities and side flow rates. Furthermore, the effects of film thickness ratios, pressure flow factors, shear flow factors, slenderness ratios, eccentricities and inlet pressures on the variations of cavitation regions are also discussed. 相似文献