全文获取类型
收费全文 | 6541篇 |
免费 | 8篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 27篇 |
建筑科学 | 5篇 |
能源动力 | 9篇 |
轻工业 | 5篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 9篇 |
一般工业技术 | 12篇 |
冶金工业 | 6461篇 |
自动化技术 | 16篇 |
出版年
2023年 | 2篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 10篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 157篇 |
1998年 | 1922篇 |
1997年 | 1133篇 |
1996年 | 757篇 |
1995年 | 389篇 |
1994年 | 346篇 |
1993年 | 387篇 |
1992年 | 50篇 |
1991年 | 102篇 |
1990年 | 104篇 |
1989年 | 89篇 |
1988年 | 101篇 |
1987年 | 87篇 |
1986年 | 76篇 |
1985年 | 59篇 |
1983年 | 12篇 |
1982年 | 32篇 |
1981年 | 48篇 |
1980年 | 57篇 |
1978年 | 26篇 |
1977年 | 180篇 |
1976年 | 350篇 |
1975年 | 10篇 |
1955年 | 4篇 |
1954年 | 3篇 |
1924年 | 1篇 |
排序方式: 共有6549条查询结果,搜索用时 15 毫秒
91.
V Launay F Gottrand L Michaud E Masy D Turck JP Farriaux 《Canadian Metallurgical Quarterly》1997,4(1):40-43
The kidney bears the brunt of the demands of a tropical climate for water and electrolyte homeostasis. We hypothesised that a tropical climate may cause adaptive changes in the entire organism leading to altered renal function in our subjects. Hence renal function data for residents of a temperate climate may not be applicable to tropical residents. We therefore sought to elucidate renal function in subjects residing in a tropical climate. We used lithium clearance, CLi, a non-invasive tool for assessing proximal tubular function in humans, and endogenous creatinine clearance, CCr, to estimate proximal tubular function and glomerular function, respectively, in our subjects. We did this in order to establish whether or not nephron function in our subjects differs from that for residents of a temperate climate. Nineteen male and 12 female Ghanaian subjects aged between 15 and 48 years were studied. The estimated GCr was 117.3 +/- 6.6 ml/min for male subjects and 97 +/- 6.4 ml/min for female subjects. CLi was 20.3 +/- 1.6 ml/min for male and 19.1 +/- 0.4 ml/min for female subjects, respectively. The estimated absolute reabsorption rate of fluid of proximal tubules was 97.0 +/- 6.0 ml/min for males and 78.1 +/- 6.0 ml/min for females. The percentage proximal fluid reabsorption for male and female subjects was 81.2 +/- 1.4 and 79.5 +/- 1.6, respectively. The differences between male and female values (mean +/- SEM) were not statistically significant. The data suggest that the proximal tubule in residents of a tropical climate may reabsorb more fluid compared to that in residents of a temperate climate. Our values for proximal tubular reabsorption are higher than those reported for residents of a temperature climate. Our estimate of glomerular filtration, however, is similar to published data for Caucasians. The difference in proximal tubular function may reflect possible renal adaptation to a hot, humid climate. We conclude that renal function of tropical residents differs from that of residents of a temperate climate. This difference may be due to renal adaptation to the hot, tropical climate. 相似文献
92.
93.
94.
95.
96.
97.
B Mauroy M Chive X Stefaniak D Demetriou B Prevost B Hattab JP Sozanski B Carpentier J Biserte E Mazeman 《Canadian Metallurgical Quarterly》1997,32(2):198-208
The role(s) of protein kinases in the regulation of G protein-dependent activation of phosphatidylinositol-specific phospholipase C by tumor necrosis factor-alpha was investigated in the osteoblast cell line MC3T3-E1. We have previously reported the stimulatory effects of tumor necrosis factor-alpha and A1F4-, an activator of G proteins, on this phospholipase pathway documented by a decrease in mass of PI and release of diacylglycerol. In this study, we further explored the mechanism(s) by which the tumor necrosis factor or A1F4(-)-promoted breakdown of phosphatidylinositol and the polyphosphoinositides by phospholipase C is regulated. Tumor necrosis factor-alpha was found to elicit a 4-5-fold increase in the formation of [3H]inositol-1,4-phosphate and [3H]inositol-1,4,5-phosphate; and a 36% increase in [3H]inositol-1-phosphate within 5 min in prelabeled cells. [3H]inositol-4-phosphate, a metabolite of [3H]inositol-1,4-phosphate and [3H]inositol-1,4,5-phosphate, was found to be the predominant phosphoinositol product of tumor necrosis factor-alpha and A1F4(-)-activated phospholipase C hydrolysis after 30 min. In addition, the preincubation of cells with pertussis toxin decreased the tumor necrosis factor-induced release of inositol phosphates by 53%. Inhibitors of protein kinase C, including Et-18-OMe and H-7, dramatically decreased the formation of [3H]inositol phosphates stimulated by either tumor necrosis factor-alpha or A1F4- by 90-100% but did not affect basal formation. The activation of cAMP-dependent protein kinase, or protein kinase A, by the treatment of cells with forskolin or 8-BrcAMP augmented basal, tumor necrosis factor-alpha and A1F4(-)-induced [3H]inositol phosphate formation. Therefore, we report that protein kinases can regulate tumor necrosis factor-alpha-initiated signalling at the cell surface in osteoblasts through effects on the coupling between receptor, G-protein and phosphatidylinositol-specific phospholipase C. 相似文献
98.
N Akuta SE Lloyd T Igarashi H Shiraga T Matsuyama S Yokoro JP Cox RV Thakker 《Canadian Metallurgical Quarterly》1997,52(4):911-916
We designed the present study to examine the cross-sectional relation between age-related lens opacities and vitamin C supplement use over a 10-12-y period before assessment of lens status in women without diagnosed cataract or diabetes. This design avoids biased measurement of nutrient intake that results when knowledge of lens opacities influences nutrition-related behavior or its reporting. The participants were 247 Boston-area women aged 56-71 y selected from the Nurses' Health Study cohort with oversampling of women with high or low vitamin C intakes. Lens opacities were graded with the Lens Opacification Classification System II. Use of vitamin C supplements for > or = 10 y (n = 26) was associated with a 77% lower prevalence of early lens opacities (odds ratio: 0.23; 95% CI: 0.09, 0.60) at any lens site and a 83% lower prevalence of moderate lens opacities (odds ratio: 0.17; 95% CI: 0.03, 0.85) at any lens site compared with women who did not use vitamin C supplements (n = 141) after adjustment for age and other potentially confounding variables. Women who consumed vitamin C supplements for < 10 y showed no evidence of a reduced prevalence of early opacities. These data, together with data from earlier experimental and epidemiologic studies, suggest that long-term consumption of vitamin C supplements may substantially reduce the development of age-related lens opacities. 相似文献
99.
I Schrijver-Wieling GH van Rens D Wittebol-Post JA Smeitink JP de Jager HB de Klerk GH van Lith 《Canadian Metallurgical Quarterly》1997,81(4):291-294
We report a case of Bellini duct carcinoma of the left kidney with invasive growth pattern. A 39-year-old man was admitted to our hospital with the chief complaint of gross hematuria. Ultrasonography showed left renal swelling but normal reniform configuration of the kidney was maintained. Computed tomography demonstrated a low density tumor infiltrating into the renal cortex and with tumor extension into the renal vein. Renal angiography revealed a hypovascular tumor. We suspected a left renal cell carcinoma with tumor extension into the left renal vein, and performed radical nephrectomy. Macroscopically, the resected kidney had a normal outer contour. The tumor with infiltrative growth pattern existed in renal medulla. Histopathologic examination revealed a papillary adenocarcinoma originated in Bellini duct (pT3bN2M0). The patient underwent systemic chemotherapy (M-VAC). This case showed invasive growth pattern, which were different from the usual renal cell carcinoma and Bellini duct carcinoma. 相似文献
100.
前脂质体技术在食品原料包埋的应用 总被引:2,自引:0,他引:2
Jean Pierre Arnaud 《中国食品工业》1997,(12):36-37
<正> 长期以来,脂质体大都应用于化妆品和医药领域中,直至近年才在农业和食品工业上,显示出巨大的应用潜力。借助于前脂质体技术(Pro-Liposome Approach)的应用,生产商可以采用脂质体包埋许多不同种类的化合物,如酶、香精、矿物质和维生素等,有助提高产率和产品的质量。 前脂质体技术包埋原理 前脂质体技术的开发,为脂质体的形 相似文献