全文获取类型
收费全文 | 104797篇 |
免费 | 9721篇 |
国内免费 | 7623篇 |
专业分类
电工技术 | 3949篇 |
技术理论 | 5篇 |
综合类 | 11832篇 |
化学工业 | 13900篇 |
金属工艺 | 6632篇 |
机械仪表 | 5449篇 |
建筑科学 | 27380篇 |
矿业工程 | 4456篇 |
能源动力 | 2573篇 |
轻工业 | 5632篇 |
水利工程 | 5357篇 |
石油天然气 | 4523篇 |
武器工业 | 895篇 |
无线电 | 5523篇 |
一般工业技术 | 10433篇 |
冶金工业 | 3999篇 |
原子能技术 | 661篇 |
自动化技术 | 8942篇 |
出版年
2024年 | 440篇 |
2023年 | 1488篇 |
2022年 | 2839篇 |
2021年 | 3236篇 |
2020年 | 3206篇 |
2019年 | 2651篇 |
2018年 | 2523篇 |
2017年 | 3171篇 |
2016年 | 3331篇 |
2015年 | 3574篇 |
2014年 | 6556篇 |
2013年 | 5444篇 |
2012年 | 7238篇 |
2011年 | 8023篇 |
2010年 | 6278篇 |
2009年 | 6738篇 |
2008年 | 6117篇 |
2007年 | 7334篇 |
2006年 | 6697篇 |
2005年 | 5961篇 |
2004年 | 4903篇 |
2003年 | 4287篇 |
2002年 | 3577篇 |
2001年 | 2952篇 |
2000年 | 2556篇 |
1999年 | 2115篇 |
1998年 | 1677篇 |
1997年 | 1395篇 |
1996年 | 1068篇 |
1995年 | 926篇 |
1994年 | 850篇 |
1993年 | 539篇 |
1992年 | 508篇 |
1991年 | 406篇 |
1990年 | 331篇 |
1989年 | 238篇 |
1988年 | 186篇 |
1987年 | 113篇 |
1986年 | 90篇 |
1985年 | 85篇 |
1984年 | 74篇 |
1983年 | 62篇 |
1982年 | 76篇 |
1981年 | 31篇 |
1980年 | 71篇 |
1979年 | 48篇 |
1978年 | 12篇 |
1975年 | 12篇 |
1959年 | 12篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
袁永强 《有色冶金设计与研究》2003,24(3):39-42
结合工程实例,对采用传统的短木桩加新兴的土工合成材料——土工网及碎石垫层构成复合基础,处理河岸挡墙软基进行探讨,该方法在软土层厚度不超过4.0m的条件下,技术可靠,施工简单,工期短,造价低。 相似文献
32.
33.
城市化进程中的小城镇交通初探 总被引:4,自引:0,他引:4
通过对小城镇城市结构、路网结构、交通结构和交通管理特征进行详细分析,得出小城镇交通问题症结所在,并初步提出小城镇交通规划和交通治理的对策。 相似文献
34.
This study examined the role of marital conflict structure--who desires and requests change versus who responds to the change request--in spouses' cardiovascular responses to marital interactions. Forty-one couples discussed 2 marital topics: one in which the wife desired change in the husband, and one in which the husband desired change in the wife. Cardiovascular responses were assessed at 2-min intervals. Results indicated that marital conflict structure moderates cardiovascular reactivity during negative marital interactions: Husbands and wives whose interactions were characterized by high levels of negative behavior showed the most pronounced diastolic blood pressure reactivity, but only when they were in the role of desiring change in their spouses. Implications for gender differences in marital conflict physiology are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
35.
Randall Billi; Moss Helen E.; Rodd Jennifer M.; Greer Mike; Tyler Lorraine K. 《Canadian Metallurgical Quarterly》2004,30(2):393
Patients with category-specific deficits have motivated a range of hypotheses about the structure of the conceptual system. One class of models claims that apparent category dissociations emerge from the internal structure of concepts rather than fractionation of the system into separate substores. This account claims that distinctive properties of concepts in the living domain are vulnerable because of their weak correlation with other features. Given the assumption that mutual activation among correlated properties produces faster activation in the normal system, the authors predicted a disadvantage for the distinctive features of living things for unimpaired adults. Results of a speeded feature verification study supported this prediction, as did a computational simulation in which networks mapped from orthography to semantics. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
36.
37.
Ramon R. Costa Liu Hsu 《International Journal of Adaptive Control and Signal Processing》1992,6(1):19-33
A variable structure model reference adaptive controller (VS-MRAC) using only input and output measurements was recently proposed and shown to be globally asymptotically stable with superior transient behaviour and disturbance rejection properties. In this paper a singular perturbation approach is used in order to establish the robustness of the controller in the presence of unmodelled dynamics (parasitics) and disturbances. We develop a new Lyapunov-based technique to analyse the overall system and show that for sufficiently small parasitics the system remains stable and the output error is small in some sense. 相似文献
38.
Rein Smedinga 《Discrete Event Dynamic Systems》1993,2(3-4):265-297
To model qualitative aspects of discrete event systems, i.e., the order of the events is of sole importance, we use a triple consisting of the set of all possible events (the alphabet), the set of all behavior (possible strings of events), and the set of all tasks (completed behavior). We use this view to model synchronous as well as asynchronous connection of systems. Moreover, it is easy to define notions like deadlock and livelock in this view. We give a method to construct a second system that, in connection with the original system, gets rid of its deadlock and/or livelock. A state-space representation is introduced. In this representation computations can be done effectively. 相似文献
39.
The effect of oxygen content on superconductivity of the 2212 and 2223 phase has been studied. By comparing the excess oxygen, the modulation vector, the XRD patterns, and the electric resistivity of 2212 and 2223 phase samples obtained with different post-annealing conditions, i.e., annealing at 600°C or quenching from 860°C, it was found that the super-conductivity is markedly influenced by both the defect distribution in non-Bi layers and the interstitial oxygens incorporated in the Bi-O layers. A tentative explanation for this is given. 相似文献
40.
分析了WTG420铁路罐车用钢的组织结构和力学性能。提出了冶炼与轧制的技术关键,其一,添加稀土元素改善钢中夹杂物;其二,采用控轧控冷使铁素体晶粒细化。 相似文献