全文获取类型
收费全文 | 71615篇 |
免费 | 8741篇 |
国内免费 | 6271篇 |
专业分类
电工技术 | 4913篇 |
技术理论 | 12篇 |
综合类 | 8698篇 |
化学工业 | 2156篇 |
金属工艺 | 709篇 |
机械仪表 | 3047篇 |
建筑科学 | 5687篇 |
矿业工程 | 1556篇 |
能源动力 | 868篇 |
轻工业 | 831篇 |
水利工程 | 1951篇 |
石油天然气 | 766篇 |
武器工业 | 1056篇 |
无线电 | 13037篇 |
一般工业技术 | 3945篇 |
冶金工业 | 2445篇 |
原子能技术 | 251篇 |
自动化技术 | 34699篇 |
出版年
2024年 | 129篇 |
2023年 | 1029篇 |
2022年 | 1734篇 |
2021年 | 1982篇 |
2020年 | 2319篇 |
2019年 | 1824篇 |
2018年 | 1671篇 |
2017年 | 2186篇 |
2016年 | 2554篇 |
2015年 | 2945篇 |
2014年 | 4783篇 |
2013年 | 4791篇 |
2012年 | 5344篇 |
2011年 | 5710篇 |
2010年 | 4463篇 |
2009年 | 4994篇 |
2008年 | 5308篇 |
2007年 | 5512篇 |
2006年 | 4742篇 |
2005年 | 4102篇 |
2004年 | 3554篇 |
2003年 | 3091篇 |
2002年 | 2357篇 |
2001年 | 1992篇 |
2000年 | 1599篇 |
1999年 | 1161篇 |
1998年 | 909篇 |
1997年 | 753篇 |
1996年 | 629篇 |
1995年 | 496篇 |
1994年 | 421篇 |
1993年 | 319篇 |
1992年 | 224篇 |
1991年 | 158篇 |
1990年 | 110篇 |
1989年 | 101篇 |
1988年 | 80篇 |
1987年 | 53篇 |
1986年 | 44篇 |
1985年 | 77篇 |
1984年 | 83篇 |
1983年 | 68篇 |
1982年 | 55篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1979年 | 22篇 |
1977年 | 9篇 |
1966年 | 8篇 |
1965年 | 12篇 |
1964年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
71.
为探讨能源消费结构调节下异质性环境规制对绿色全要素生产率的影响机制,论文利用SBM方向距离函数测得全国各省市“经济-资源-环境-社会”四位一体的绿色全要素生产率,并将环境规制工具分为命令控制型、经济激励型、治理投入型和公众参与型4类,构建了空间杜宾模型以及门槛效应模型,进而得出在能源消费结构调节下,异质性环境规制对绿色全要素生产率的直接作用、间接作用以及空间溢出效应。研究结果表明:1)经济激励型和公众参与型环境规制通过调节能源消费结构对当地和邻地的绿色全要素生产率产生影响;2)在门槛检验方面,能源消费结构对命令控制型、经济激励型和公众参与型环境规制影响绿色全要素生产率存在门槛效应,同时在能源消费结构调节下,命令控制型和经济激励型环境规制对其本身对绿色全要素生产率的间接作用存在门槛效应。建议政府在制定环境规制时要考虑到其与能源消费结构的交互作用,并且在不同能源消费水平地区采用适宜的规制方法和强度,以更好地发挥环境规制作用。 相似文献
72.
Carmen Camarero Izquierdo Javier Rodríguez Pinto Rebeca San José-Cabezudo 《Telematics and Informatics》2018,35(5):1176-1189
This research explores how digital publications may be turned into something more than just a meeting point for people who are seeking information and may become a latent community. The paper proposes that the network of editors, followers, and advertisers of digital publications determine the user sense of community towards the publication. While the pattern of connections among editors and followers reinforces the sense of community, advertisers act as intruders who weaken the feasibility of building a community. Data were collected from followers of digital publications. The dynamics of the sense of community is described as a process in which informational value and identification are essential to nurturing readers’ soft or hard commitment. Findings indicate that the strong ties between editors and followers as well as the diversity positively impacts on informational value and identification, whereas advertising intrusiveness diminishes the informational value. 相似文献
73.
Georgia-Ioanna Kartalou Ana Rita Salgueiro-Pereira Thomas Endres Angelina Lesnikova Plinio Casarotto Paula Pousinha Kevin Delanoe Elke Edelmann Eero Castrn Kurt Gottmann Hlne Marie Volkmar Lessmann 《International journal of molecular sciences》2020,21(23)
Therapeutic approaches providing effective medication for Alzheimer’s disease (AD) patients after disease onset are urgently needed. Previous studies in AD mouse models suggested that physical exercise or changed lifestyle can delay AD-related synaptic and memory dysfunctions when treatment started in juvenile animals long before onset of disease symptoms, while a pharmacological treatment that can reverse synaptic and memory deficits in AD mice was thus far not identified. Repurposing food and drug administration (FDA)-approved drugs for treatment of AD is a promising way to reduce the time to bring such medication into clinical practice. The sphingosine-1 phosphate analog fingolimod (FTY720) was approved recently for treatment of multiple sclerosis patients. Here, we addressed whether fingolimod rescues AD-related synaptic deficits and memory dysfunction in an amyloid precursor protein/presenilin-1 (APP/PS1) AD mouse model when medication starts after onset of symptoms (at five months). Male mice received intraperitoneal injections of fingolimod for one to two months starting at five to six months. This treatment rescued spine density as well as long-term potentiation in hippocampal cornu ammonis-1 (CA1) pyramidal neurons, that were both impaired in untreated APP/PS1 animals at six to seven months of age. Immunohistochemical analysis with markers of microgliosis (ionized calcium-binding adapter molecule 1; Iba1) and astrogliosis (glial fibrillary acid protein; GFAP) revealed that our fingolimod treatment regime strongly down regulated neuroinflammation in the hippocampus and neocortex of this AD model. These effects were accompanied by a moderate reduction of Aβ accumulation in hippocampus and neocortex. Our results suggest that fingolimod, when applied after onset of disease symptoms in an APP/PS1 mouse model, rescues synaptic pathology that is believed to underlie memory deficits in AD mice, and that this beneficial effect is mediated via anti-neuroinflammatory actions of the drug on microglia and astrocytes. 相似文献
74.
当今的多相催化研究需要新的技术和方法从原子尺度上表征活性中心结构和反应中间体。本文作者课题组近期开发了理论模拟新技术来探索催化剂活性位点结构,即基于神经网络势函数的大规模原子模拟(LASP)软件中实现的全局神经网络势函数计算方法。本文介绍了该方法可以显著降低催化体系的计算代价,而维持与密度泛函理论同一级别的计算精度,从而解决多相催化中的许多复杂问题。本文对神经网络势函数方法的实现细节和目前已实现的应用场景进行了详细介绍。神经网络势函数可以用来预测材料晶体结构,理解高压氢化条件下TiO2表面的结构演化和确定三元氧化物ZnCrO晶相中合成气制甲醇活性位点。最后文章分析了神经网络势函数的局限性和今后可能的三个研究方向,即材料性质预测、多元素体系神经网络势函数构造和化学反应拟合。 相似文献
75.
76.
Single image super resolution (SISR) is an important research content in the
field of computer vision and image processing. With the rapid development of deep
neural networks, different image super-resolution models have emerged. Compared to
some traditional SISR methods, deep learning-based methods can complete the superresolution tasks through a single image. In addition, compared with the SISR methods
using traditional convolutional neural networks, SISR based on generative adversarial
networks (GAN) has achieved the most advanced visual performance. In this review, we
first explore the challenges faced by SISR and introduce some common datasets and
evaluation metrics. Then, we review the improved network structures and loss functions
of GAN-based perceptual SISR. Subsequently, the advantages and disadvantages of
different networks are analyzed by multiple comparative experiments. Finally, we
summarize the paper and look forward to the future development trends of GAN-based
perceptual SISR. 相似文献
77.
The occurrence of perioperative heart failure will affect the quality of medical
services and threaten the safety of patients. Existing methods depend on the judgment of
doctors, the results are affected by many factors such as doctors’ knowledge and
experience. The accuracy is difficult to guarantee and has a serious lag. In this paper, a
mixture prediction model is proposed for perioperative adverse events of heart failure,
which combined with the advantages of the Deep Pyramid Convolutional Neural
Networks (DPCNN) and Extreme Gradient Boosting (XGBOOST). The DPCNN was
used to automatically extract features from patient’s diagnostic texts, and the text features
were integrated with the preoperative examination and intraoperative monitoring values
of patients, then the XGBOOST algorithm was used to construct the prediction model of
heart failure. An experimental comparison was conducted on the model based on the data
of patients with heart failure in southwest hospital from 2014 to 2018. The results showed
that the DPCNN-XGBOOST model improved the predictive sensitivity of the model by
3% and 31% compared with the text-based DPCNN Model and the numeric-based
XGBOOST Model. 相似文献
78.
79.
本文建立了PC结构施工全过程的BIM模型及有限元分析模型,对施工过程进行数值模拟与动态、静态监测,对装配式结构进行了结构性能评价,为结构可视化施工监测提供了技术支持。 相似文献
80.
We present new parallelization and memory-reducing strategies for the graph-theoretic color-coding approximation technique, with applications to biological network analysis. Color-coding is a technique that gives fixed parameter tractable algorithms for several well-known NP-hard optimization problems. In this work, by efficiently parallelizing steps in color-coding, we create two new biological protein interaction network analysis tools: Fascia for subgraph counting and motif finding and FastPath for signaling pathway detection. We demonstrate considerable speedup over prior work, and the optimizations introduced in this paper can also be used for other problems where color-coding is applicable. 相似文献