全文获取类型
收费全文 | 2097篇 |
免费 | 345篇 |
国内免费 | 101篇 |
专业分类
电工技术 | 30篇 |
综合类 | 164篇 |
化学工业 | 638篇 |
金属工艺 | 43篇 |
机械仪表 | 32篇 |
建筑科学 | 136篇 |
矿业工程 | 229篇 |
能源动力 | 25篇 |
轻工业 | 672篇 |
水利工程 | 29篇 |
石油天然气 | 93篇 |
武器工业 | 6篇 |
无线电 | 38篇 |
一般工业技术 | 83篇 |
冶金工业 | 167篇 |
原子能技术 | 12篇 |
自动化技术 | 146篇 |
出版年
2024年 | 24篇 |
2023年 | 64篇 |
2022年 | 214篇 |
2021年 | 220篇 |
2020年 | 110篇 |
2019年 | 126篇 |
2018年 | 100篇 |
2017年 | 99篇 |
2016年 | 93篇 |
2015年 | 81篇 |
2014年 | 133篇 |
2013年 | 135篇 |
2012年 | 136篇 |
2011年 | 112篇 |
2010年 | 97篇 |
2009年 | 78篇 |
2008年 | 76篇 |
2007年 | 85篇 |
2006年 | 79篇 |
2005年 | 63篇 |
2004年 | 56篇 |
2003年 | 54篇 |
2002年 | 53篇 |
2001年 | 38篇 |
2000年 | 35篇 |
1999年 | 27篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 16篇 |
1995年 | 19篇 |
1994年 | 18篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 9篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 1篇 |
1983年 | 5篇 |
1982年 | 1篇 |
1980年 | 5篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1961年 | 1篇 |
1958年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有2543条查询结果,搜索用时 15 毫秒
991.
Whisman Mark A.; Uebelacker Lisa A.; Settles Tatiana D. 《Canadian Metallurgical Quarterly》2010,24(3):367
Mechanisms by which poor relationship functioning contributes to poor health are not fully understood. We conducted a study to evaluate the association between marital distress and the metabolic syndrome (MetS), which refers to a clustering of characteristics that have individually been shown to be associated with elevated risk of cardiovascular disease and diabetes and which collectively have been shown to increase risk for cardiovascular disease, diabetes, stroke, and mortality. A population-based English sample of couples (N = 671 couples) in which both partners were between the ages of 52 and 79 years old completed a self-report measure of marital distress and a nurse visit that included collection of blood pressure, blood samples, and anthropometric measures. Results indicated that for women, after controlling for demographic variables, greater marital distress was significantly associated with increasing likelihood of meeting criteria for the MetS and with the individual MetS criteria of elevated blood pressure and elevated fasting glucose. The association between marital distress and the MetS remained significant for women when additionally controlling for depressive symptoms and health habits (smoking status, physical activity). Marital distress was not significantly associated with the MetS or any of the individual MetS criteria for men. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
992.
Helgeson Vicki S.; Escobar Oscar; Siminerio Linda; Becker Dorothy 《Canadian Metallurgical Quarterly》2010,29(2):153
Objective: To determine the relation of stressful life events to metabolic control. Design: We interviewed adolescents with Type 1 diabetes (n = 132; average age at enrollment = 12 years) annually for 5 years. Measures: Each year we administered measures of stressful life events, psychological distress, and self-care behavior. We downloaded data from blood glucose meters, and obtained measures of metabolic control (hemoglobin A1c) from medical records. Results: Using longitudinal growth curve modeling, stressful life events predicted greater psychological distress, poorer self-care behavior, and worse metabolic control in both cross-sectional and longitudinal (lagged) analyses. Cross-sectionally, many of these relations were stronger among older than younger adolescents. Self-care behavior partly mediated this association. Conclusion: Stressful life events are related to poor metabolic control—especially for older adolescents. A primary mechanism appears to be a lack of good self care. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
993.
清水泉铜矿床位于新疆东准噶尔地区卡拉麦里成矿带西段,产于铜背景值较高的火山岩-安山岩中。卡拉麦里深断裂呈NWW-EW向自区内北侧穿过,带内岩石均已发生变形、变质,与近EW向次级构造及裂隙构成导矿和容矿空间。岩浆活动经历华力西早、中、晚多期次侵入,超基性岩、黑云母花岗岩、更长花岗岩、霏细斑岩及火山岩广布区内,构成特定岩浆建造与矿床的时空联系及多期次成矿物质的叠加。铜矿(化)体赋存于蚀变安山岩中,与层位、构造和岩浆活动密切相关,并严格就位于次级网脉状构造和裂隙中,矿化与黄铜矿化、黄铁矿化密切相关,并接受后期石英闪长玢岩脉的成矿叠加。细脉发育部位,矿化富集增强。 相似文献
994.
为加强湘东曲溪金矿的找矿工作,采用路线地质调查、构造填图、矿床(点)考察、岩石地球化学和遥感解译等方法,对矿区地质特征和控矿因素进行研究,总结了曲溪金矿区的成矿规律和找矿标志,建立了控矿模式,即认为含金围岩是一套冷家溪群浅变质粉砂岩;区内NNE向深大断裂是导热和成矿的通道,与深大断裂走向夹角较小的次级断裂,是矿区较好的容矿断裂;区内燕山期二长花岗岩为成矿提供了部分矿质来源。根据成矿规律和找矿标志,在矿区深部及其外围圈定了沙埚里、鸡洞坑和1号脉深部3个找矿靶区。尤其是对前人工作认为的沙埚里金锑矿点,本次工作后发现其实际为一金钨矿点,这为本区下一步找矿提供了思路。 相似文献
995.
996.
丁德武 《计算机与应用化学》2014,(8):1007-1009
社团结构分析有助于理解新陈代谢网络的结构和功能关系,是新陈代谢网络研究领域的一个重要研究主题。然而,直接将复杂网络方法应用到新陈代谢网络中时,很难得到具有实际生物学意义的社团。本文首先构建了高质量人类代谢网络模型的巨强连通体,然后采用一种基于边过滤的技术研究了该巨强连通体,得到的8个主要社团均具备较好的生物学意义。研究结果表明:基于边过滤的技术可用于识别新陈代谢网络中的社团。 相似文献
997.
Zhenghong Jin Qingling Zhang Xinyou Meng 《International journal of systems science》2019,50(7):1327-1337
The problem of impulse analysis is considered for the T-S fuzzy singular system by using the Kronecker index and the generalised Kronecker index in this paper. The T-S singular system is divided into two cases: the uniformly regular T-S fuzzy singular system and the non-uniformly regular T-S fuzzy singular system. The contribution of this paper is twofold. First, a new definition of the generalised Kronecker form is introduced, and the algorithm of finding the generalised Kronecker form is given. Second, two theorems are proved, one is that the uniformly regular T-S fuzzy singular system is impulsive if and only if the Kronecker index is greater than one, the other one is the non-uniformly regular T-S fuzzy singular system is impulsive if and only if the generalised Kronecker index is greater than one. Finally, two numerical simulations and the population model with stage structure are carried out to show the consistency with theoretical analysis and illustrate the effectiveness of the algorithm. 相似文献
998.
对北方地区工厂化蔬菜生产中番茄灰霉病,番茄晚疫病和黄瓜白粉病3种主要病害的发生规律进行了详细研究,并对低温型病害(番茄灰霉病,晚疫病)以及高温型病害(黄瓜白粉病)分别提出了相应的生态防治措施;调控温湿度,阻断紫外线,高温闷棚等。 相似文献
999.
In this paper, we consider performance output tracking for a wave equation with a general boundary disturbance. The control and the disturbance are unmatched. Different from the existing results, the hidden regularity, instead of the high gain or variable structure, is utilized in the adaptive servomechanism design. As a result, we are able to cope with more complicated and general disturbances. Moreover, the performance output can track the reference signal exponentially, and at the same time, all the states of the subsystems involved are uniformly bounded. More specially, the overall closed-loop system is exponentially stable when the disturbance and reference are disconnected to the system. The numerical simulations are presented to illustrate the effect of the proposed scheme. 相似文献
1000.
以在新疆苏木达依日列克河砂金矿的野外工作为基础,分析了冲积型砂金矿中砂金分布与地貌部位、第四纪地层的关系,揭示出砂金在河道横向、纵向和垂向上富集规律。 相似文献