全文获取类型
收费全文 | 2607篇 |
免费 | 20篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 111篇 |
金属工艺 | 29篇 |
机械仪表 | 42篇 |
建筑科学 | 6篇 |
能源动力 | 27篇 |
轻工业 | 43篇 |
水利工程 | 2篇 |
无线电 | 42篇 |
一般工业技术 | 182篇 |
冶金工业 | 2025篇 |
原子能技术 | 25篇 |
自动化技术 | 87篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 18篇 |
2014年 | 15篇 |
2013年 | 64篇 |
2012年 | 26篇 |
2011年 | 26篇 |
2010年 | 37篇 |
2009年 | 33篇 |
2008年 | 31篇 |
2007年 | 26篇 |
2006年 | 28篇 |
2005年 | 19篇 |
2004年 | 22篇 |
2003年 | 16篇 |
2002年 | 8篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 61篇 |
1998年 | 602篇 |
1997年 | 325篇 |
1996年 | 257篇 |
1995年 | 168篇 |
1994年 | 114篇 |
1993年 | 116篇 |
1992年 | 24篇 |
1991年 | 49篇 |
1990年 | 36篇 |
1989年 | 24篇 |
1988年 | 30篇 |
1987年 | 38篇 |
1986年 | 34篇 |
1985年 | 39篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 16篇 |
1978年 | 9篇 |
1977年 | 37篇 |
1976年 | 114篇 |
1975年 | 14篇 |
1973年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有2629条查询结果,搜索用时 15 毫秒
61.
Proton pencil beams in water, in a format suitable for treatment planning algorithms and covering the radiotherapy energy range (50-250 MeV), have been calculated using a modified version of the Monte Carlo code PTRAN. A simple analytical model has also been developed for calculating proton broad-beam dose distributions which is in excellent agreement with the Monte Carlo calculations. Radial dose distributions are also calculated analytically and narrow proton pencil-beam dose distributions derived. The physical approximations in the Monte Carlo code and in the analytical model together with their limitations are discussed. Examples showing the use of the calculated set of proton pencil beams as input to an existing photon treatment planning algorithm based on biological optimization are given for fully 3D scanned proton pencil beams; these include intensity modulated beams with range shift and scanning in the transversal plane. 相似文献
62.
T Smith AK Hewson CI Kingsley JP Leonard ML Cuzner 《Canadian Metallurgical Quarterly》1997,150(6):1909-1917
Acute, monophasic experimental allergic encephalomyelitis (EAE) in the Lewis rat shows pathological similarities to the human disease multiple sclerosis (MS). Rats that recover from EAE are essentially resistant to disease reinduction, unlike MS in which relapses are frequently associated with common bacterial and viral infections. As macrophage-derived interleukin (IL)-12 is a critical component of innate resistance to bacterial infection and appears to directly activate encephalitogenic T cells in vivo, the ability of this cytokine to reinduce paralysis in EAE was examined. Paralytic disease was exacerbated by intraperitoneal IL-12 administration and could be reinduced up to 1 week after recovery from the primary clinical episode. Concomitant with worsening of initial clinical signs and relapse was an increase in the ratio of macrophages to T cells in brain stem perivascular cuffs and the expression of inducible nitric oxide synthase in cells with both macrophage and microglial morphology. These findings suggest that IL-12 may contribute to macrophage-mediated disease exacerbation and relapse in patients with MS. 相似文献
63.
Small-cell carcinoma (also known as oat-cell carcinoma) is a rare tumor that previously concerns the lung; small-cell carcinoma of the bladder is extremely rare (0.5% of all bladder malignancies). The Authors report here the case of a 78th years old man. Fourteen months before our observation he was submitted to a partial cystectomy for a small-cell carcinoma of the bladder cupola. There was no evidence of extra-vesical location at that moment and the patient was not submitted to any adjuvant therapy. At the moment of our observation the disease was very advanced and the patient died in a few time. The Authors discuss about the therapy of bladder small-cell carcinoma in the few cases described by the literature and about the survival of those patients. A radical surgical treatment in association with an adjuvant chemo- or radiotherapy appears as a better way to treat these patients. On account of this case the Authors agree with this choice and conclude that only a combined treatment can allow a better survival. 相似文献
64.
65.
WC Miller KE Eggert JP Wallace AK Lindeman C Jastremski 《Canadian Metallurgical Quarterly》1993,14(7):401-405
There is little evidence concerning the effectiveness of self-help materials for weight control. The purpose of this research was to evaluate a self-help weight-loss program. Obese (body fat > or = 25.0%, range = 25.0-48.6%, mean +/- SEM = 36.5 +/- 1.3%) men (n = 14) and women (n = 21) were given a workbook detailing a behavior modification approach to weight loss that emphasizes self-monitoring of diet and exercise behaviors, and then sent home for 6 months to learn how to lose weight on their own. A group of 9 controls (CONT) who did not get a workbook were used for comparison. ANOVA showed that the experimental group (EXP) lost 8.1 +/- 0.9 (mean +/- SEM) kg body weight, 6.4 +/- 0.8 kg fat, and 3.9 +/- 0.6% body fat; all significant over time (p < 0.001) and different from the CONT (p < 0.0001) who showed no change in these variables. The EXP also reduced their fat intake (% of joules) from 36.1 +/- 1.0% to 27.9 +/- 1.3% (p < 0.0001), increased their carbohydrate intake from 45.7 +/- 1.2% to 50.0 +/- 1.7% (p < 0.007) and their protein intake from 16.3 +/- 0.05% to 20.7 +/- 0.7% (0 < 0.03), all of which were significantly different (p < 0.03) than the CONT who did not change. Dietary fiber increased in the EXP from 19.8 +/- 1.4 to 27.3 +/- 2.2 g/d (p < 0.001) even with a significant reduction in energy intake (11.3 +/- 0.6 vs. 8.9 +/- 0.5 Mj/d; p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
66.
Isolation of Shigella dysenteriae serotypes 11, 12, and 13 from patients with diarrhea in Bangladesh
M Ansaruzzaman AK Kibriya AK Mitra RB Sack MJ Albert 《Canadian Metallurgical Quarterly》1993,31(5):1392-1393
Nine isolates of bacteria biochemically resembling Shigella dysenteriae but not belonging to the 10 recognized serotypes were isolated from patients with diarrhea in Bangladesh. Further studies suggested that two, one, and six isolates belonged to the recently recognized S. dysenteriae serotypes 11, 12, and 13, respectively. 相似文献
67.
68.
69.
N Mittal N Gupta S Saksena N Goyal U Roy AK Rastogi 《Canadian Metallurgical Quarterly》1998,63(20):1823-1834
The prevalent drugs for treatment of kala azar viz. sodium stibogluconate (SSG) and pentamidine cause severe toxic side effects and acute immunosuppression in the treated individuals. Picroliv, a standardized mixture of iridoid glycosides, prepared from the alcoholic extract of the root and rhizome of Picrorhiza kurroa has shown strong hepatoprotective activity against several models of hepatotoxicity. Therefore, the present study was undertaken with an objective to study the effects of Picroliv (12.5 mg/kg x 7 days oral) alone and in combination with SSG on parasitemia, lipid peroxidation and hepatic marker enzymes of golden hamsters during Leishmania donovani infection. The results indicated a marked hepatoprotective effect of Picroliv in terms of biochemical markers, and a significant antileishmanial activity implying that it can be utilized as an adjunct to chemotherapy or in combination therapy of kala azar along with sodium stibogluconate, thus enhancing the efficacy of antileishmanials. 相似文献
70.