全文获取类型
收费全文 | 8608篇 |
免费 | 817篇 |
国内免费 | 584篇 |
专业分类
电工技术 | 859篇 |
综合类 | 660篇 |
化学工业 | 1293篇 |
金属工艺 | 543篇 |
机械仪表 | 519篇 |
建筑科学 | 547篇 |
矿业工程 | 222篇 |
能源动力 | 244篇 |
轻工业 | 1170篇 |
水利工程 | 225篇 |
石油天然气 | 137篇 |
武器工业 | 80篇 |
无线电 | 731篇 |
一般工业技术 | 761篇 |
冶金工业 | 643篇 |
原子能技术 | 194篇 |
自动化技术 | 1181篇 |
出版年
2024年 | 33篇 |
2023年 | 95篇 |
2022年 | 247篇 |
2021年 | 353篇 |
2020年 | 224篇 |
2019年 | 224篇 |
2018年 | 215篇 |
2017年 | 247篇 |
2016年 | 232篇 |
2015年 | 319篇 |
2014年 | 440篇 |
2013年 | 555篇 |
2012年 | 673篇 |
2011年 | 669篇 |
2010年 | 589篇 |
2009年 | 613篇 |
2008年 | 631篇 |
2007年 | 534篇 |
2006年 | 489篇 |
2005年 | 433篇 |
2004年 | 354篇 |
2003年 | 299篇 |
2002年 | 291篇 |
2001年 | 250篇 |
2000年 | 180篇 |
1999年 | 96篇 |
1998年 | 144篇 |
1997年 | 103篇 |
1996年 | 56篇 |
1995年 | 40篇 |
1994年 | 60篇 |
1993年 | 52篇 |
1992年 | 23篇 |
1991年 | 15篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1977年 | 11篇 |
1976年 | 19篇 |
1975年 | 7篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
2.
本实验采用4D-非标记蛋白质组学技术研究秦川牛肉贮藏过程中(0~8 d)肌红蛋白含量及其衍生物的转化情况,阐释冷却秦川牛肉中肌红蛋白含量及其衍生物转化的分子机制。结果表明:贮藏过程中,肌红蛋白表达量在宰后0~4 d上升、4~8 d下降,利用非标记蛋白质组学技术鉴定出与肌红蛋白及其衍生物相关的差异蛋白14 种,具体包括代谢酶、氧化还原酶、过氧化物酶、伴侣蛋白4 类,这4 类蛋白的表达共同调控贮藏过程中肌红蛋白含量的变化及其3 种衍生物之间的转化,具体表现为贮藏过程中肌红蛋白表达量整体呈下降趋势,氧合肌红蛋白相对含量持续下降,脱氧肌红蛋白、高铁肌红蛋白相对含量逐渐增加,导致肉色发生褐变。本研究结果有利于理解秦川牛肉贮藏过程肉类变色的复杂生化变化机制。 相似文献
3.
Breast cancer is the most frequently diagnosed cancer in women worldwide. The disease and its treatments exert profound effects on an individual’s physical and mental health. There are many factors that impact an individual’s risk of developing breast cancer, their response to treatments, and their risk of recurrence. The community of microorganisms inhabiting the gastrointestinal tract, the gut microbiota, affects human health through metabolic, neural, and endocrine signaling, and immune activity. It is through these mechanisms that the gut microbiota appears to influence breast cancer risk, response to treatment, and recurrence. A disrupted gut microbiota or state of ‘dysbiosis’ can contribute to a biological environment associated with higher risk for cancer development as well as contribute to negative treatment side-effects. Many cancer treatments have been shown to shift the gut microbiota toward dysbiosis; however, the microbiota can also be positively manipulated through diet, prebiotic and probiotic supplementation, and exercise. The objective of this review is to provide an overview of the current understanding of the relationship between the gut microbiota and breast cancer and to highlight potential strategies for modulation of the gut microbiota that could lead to improved clinical outcomes and overall health in this population. 相似文献
4.
5.
6.
7.
Photoluminescence features in a commercial grade cured DGEBA-based epoxy resin have been investigated with as objective to determine which of the material compounds are responsible for cured resin emissions. The origin of the bands has been approached by considering photoluminescence of base resin and hardener taken separately, of their mixture, and in the course of curing. Most of the bands observed in the cured resin could be interpreted based on those found in the components taken separately. Fluorescence of the cured resin appears dominated by two broad bands that are characteristic of the hardener and exhibits a blue shift by up to 30 nm in the course of curing which could be used for cure monitoring purpose of the investigated system. Fluorescence of the base resin is clearly detected in the resin cured with tertiary amine as catalyser. However, it is very weak if the catalyser is not added. Two phosphorescence processes have been isolated in the cured resin, one of them being related to the base resin. Finally, a chemiluminescence spectrum has been recorded in the course of curing, which has been related to either curing-related reactions or to an oxidation process. 相似文献
8.
2BE1系列水环真空泵越来越广泛地应用于煤矿抽排瓦斯气体,其选型的正确性对煤矿瓦斯抽放安全至关重要。介绍了2BE1系列水环真空泵的工作原理,以及在煤矿瓦斯气体抽放中的应用和选型。 相似文献
9.
S Bastian JL Paquet C Robert B Cremers B Loillier JF Larrivée DR Bachvarov F Marceau D Pruneau 《Canadian Metallurgical Quarterly》1998,253(3):750-755
Near-haploidy is a rare cytogenetic finding in childhood acute lymphoblastic leukaemia (ALL) and is associated with a poor prognosis. A second hyperdiploid line, occurring presumably by endoreduplication of the near-haploid stemline, is often observed. We present a case of common ALL in relapse characterized morphologically by a dual population of small and large lymphoblasts. Cytogenetic analysis supplemented with fluorescence in-situ hybridization (FISH) studies localized near-haploidy and hyperdiploidy to the small and large blast population respectively. DNA ploidy determination confirmed two abnormal clones with near-haploidy as the predominant one. A novel t(9;12)(q11;q13) was present in the near-haploid clone and was duplicated in the hyperdiploid clone. This finding identified cells bearing near-haploidy to be the clonogenic population following malignant transformation and confirmed endoreduplication as the mechanism for the presence of associated hyperdiploidy. 相似文献
10.
The alarm lists presented to control center operators are usually difficult to interpret. The authors present an expert system that processes the alarm lists in Portuguese control centers. This system makes an intelligent synthesis of the available information and presents it in a flexible and structured way. It uses an original approach to deal with temporal reasoning and real-time constraints. The system incorporates an explanation module that enables its use as a tutor for novice operators 相似文献