全文获取类型
收费全文 | 3757篇 |
免费 | 454篇 |
国内免费 | 212篇 |
专业分类
电工技术 | 337篇 |
综合类 | 247篇 |
化学工业 | 635篇 |
金属工艺 | 164篇 |
机械仪表 | 268篇 |
建筑科学 | 272篇 |
矿业工程 | 95篇 |
能源动力 | 168篇 |
轻工业 | 390篇 |
水利工程 | 81篇 |
石油天然气 | 121篇 |
武器工业 | 13篇 |
无线电 | 397篇 |
一般工业技术 | 488篇 |
冶金工业 | 119篇 |
原子能技术 | 52篇 |
自动化技术 | 576篇 |
出版年
2024年 | 46篇 |
2023年 | 117篇 |
2022年 | 199篇 |
2021年 | 273篇 |
2020年 | 201篇 |
2019年 | 150篇 |
2018年 | 176篇 |
2017年 | 178篇 |
2016年 | 165篇 |
2015年 | 184篇 |
2014年 | 260篇 |
2013年 | 303篇 |
2012年 | 342篇 |
2011年 | 270篇 |
2010年 | 239篇 |
2009年 | 235篇 |
2008年 | 185篇 |
2007年 | 153篇 |
2006年 | 153篇 |
2005年 | 104篇 |
2004年 | 90篇 |
2003年 | 64篇 |
2002年 | 73篇 |
2001年 | 54篇 |
2000年 | 36篇 |
1999年 | 31篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 27篇 |
1995年 | 11篇 |
1994年 | 17篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1970年 | 1篇 |
1962年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有4423条查询结果,搜索用时 15 毫秒
71.
Anwar Syed Muhammad Irmakci Ismail Torigian Drew A. Jambawalikar Sachin Papadakis Georgios Z. Akgun Can Ellermann Jutta Akcakaya Mehmet Bagci Ulas 《Journal of Signal Processing Systems》2022,94(5):497-510
Journal of Signal Processing Systems - Segmentation of thigh tissues (muscle, fat, inter-muscular adipose tissue (IMAT), bone, and bone marrow) from magnetic resonance imaging (MRI) scans is useful... 相似文献
72.
Ad hoc网络是一种无中心的自组织网络,由于用户能量受限当信噪比较低时有效用户识别的可靠性和信道安全性下降.该文针对这个问题提出一种联合有效用户识别与信道安全编译码方法.将发送用户的正交地址码与接收用户的伪随机地址码异或产生基于发送用户与接收用户的有效用户识别码.为提高信道安全性以信道安全码作为密钥加密有效用户识别码得到正交随机安全序列.为实现扩频并提高传输效率将发送数据以6 bit信息作为一个符号进行分组,将每个符号与一个正交随机安全序列对应.接收用户采用基于子空间的方法处理接收信号,通过建立判决模型识别有效用户.实验结果表明该方法与已有方法相比,当有效用户识别的漏警概率为10–3时信噪比增益改善1.6 dB. 相似文献
73.
74.
Poly(N‐phenylglycine)‐Based Nanoparticles as Highly Effective and Targeted Near‐Infrared Photothermal Therapy/Photodynamic Therapeutic Agents for Malignant Melanoma
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bang‐Ping Jiang Li Zhang Xiao‐Lu Guo Xing‐Can Shen Yan Wang Yang Zhu Hong Liang 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(8)
Malignant melanoma is a highly aggressive tumor resistant to chemotherapy. Therefore, the development of new highly effective therapeutic agents for the treatment of malignant melanoma is highly desirable. In this study, a new class of polymeric photothermal agents based on poly(N‐phenylglycine) (PNPG) suitable for use in near‐infrared (NIR) phototherapy of malignant melanoma is designed and developed. PNPG is obtained via polymerization of N‐phenylglycine (NPG). Carboxylate functionality of NPG allows building multifunctional systems using covalent bonding. This approach avoids complicated issues typically associated with preparation of polymeric photothermal agents. Moreover, PNPG skeleton exhibits pH‐responsive NIR absorption and an ability to generate reactive oxygen species, which makes its derivatives attractive photothermal therapy (PTT)/photodynamic therapy (PDT) dual‐modal agents with pH‐responsive features. PNPG is modified using hyaluronic acid (HA) and polyethylene glycol diamine (PEG‐diamine) acting as the coupling agent. The resultant HA‐modified PNPG (PNPG‐PEG‐HA) shows negligible cytotoxicity and effectively targets CD44‐overexpressing cancer cells. Furthermore, the results of in vitro and in vivo experiments reveal that PNPG‐PEG‐HA selectively kills B16 cells and suppresses malignant melanoma tumor growth upon exposure to NIR light (808 nm), indicating that PNPG‐PEG‐HA can serve as a very promising nanoplatform for targeted dual‐modality PTT/PDT of melanoma. 相似文献
75.
Can Zhang Shijie Zhan Jian Wang Zhongjian Liu Hong You Yuhong Jia 《Clean Technologies and Environmental Policy》2017,19(4):991-1001
Recently, interspecies quorum quenching (QQ) by bacteria has been reported as a novel approach in biofouling control in membrane bioreactor (MBR) for wastewater treatment. In this study, seven QQ bacteria, named RO1 to RO7, were isolated from fouling reverse osmosis (RO) membrane and were encapsulated in the microbial filters for biofouling control in MBR. Results showed that all isolates have extracellular QQ activity, and RO1 to RO6 were characterized as heat-stable enzymatic degradation of N-acyl homoserine lactones (AHLs), while RO7 was mainly pH-dependent. Analysis of the 16S rRNA gene indicated that RO7 was a species of Pseudomonas sp., others belonged to the species of Bacillus, Stenotrophomonas maltophilia and Delftia tsuruhatensis, respectively. Then, the microbial filters encapsulated each isolate were applied in a laboratory-scaled MBR and proved the substantial inhibition effect on membrane biofouling except for RO7, indicating that QQ bacteria employing enzymes to degrade AHLs have great potential in biofouling control in MBR. 相似文献
76.
The assembly line worker assignment and balancing problem type-II (ALWABP-2) occurs when workers and tasks (where task times depend on workers’ skills) are to be simultaneously assigned to a fixed number of workstations with the goal of minimising the cycle time. In this study, a two-phase variable neighbourhood search (VNS) algorithm is proposed to solve the ALWABP-2 due to the NP-hard nature of this problem. In the first phase of the algorithm, a VNS approach is applied to assign tasks to workstations with the aim of minimising the cycle time while in the second phase, a variable neighbourhood descent method is applied to assign workers to workstations. The performance of the proposed algorithm is tested on well-known benchmark instances. In addition, the proposed algorithm has been used to solve a real case study from a consumer electronics company that manufactures LCD TVs. The results show that the algorithm is superior to the methods reported in the literature in terms of its higher efficiency and robustness. Furthermore, the algorithm is easy to implement and significantly improves the performance of the final assembly line for the investigated LCD TV real case study. 相似文献
77.
Can Ekici 《International Journal of Thermophysics》2016,37(5):48
Fanger’s predicted mean vote (PMV) equation is the result of the combined quantitative effects of the air temperature, mean radiant temperature, air velocity, humidity activity level and clothing thermal resistance. PMV is a mathematical model of thermal comfort which was developed by Fanger. The uncertainty budget of the PMV equation was developed according to GUM in this study. An example is given for the uncertainty model of PMV in the exemplification section of the study. Sensitivity coefficients were derived from the PMV equation. Uncertainty budgets can be seen in the tables. A mathematical model of the sensitivity coefficients of \(T_{\mathrm{a}}\), \(h_{\mathrm{c}}\), \(T_{\mathrm{mrt}}\), \(T_{\mathrm{cl}}\), and \(P_{\mathrm{a}}\) is given in this study. And the uncertainty budgets for \(h_{\mathrm{c}}\), \(T_{\mathrm{cl}}\), and \(P_{\mathrm{a}}\) are given in this study. 相似文献
78.
选用5-5′键型连接的木质素二聚体为研究对象,基于B3LYP/6-31g基组和密度泛函理论(DFT)对其进行了高温热解微观化学反应机理研究,设计了5-5′型木质素二聚体高温热解反应的5条初反应路径,并在分析初反应结果的基础上设计了7条次反应路径,对每条路径的反应物及其产物进行了结构优化,计算了1500K温度下每条反应路径的热力学及动力学参数。结果表明,5-5′型木质素苯环位上的甲氧基具有很强的活性,甲氧基中O-CH3键以及Caromatic-OCH3键较易断裂;通过计算得出初反应的R3、R4反应焓变较小,分别为192.7kJ/mol和270.5kJ/mol,认为该热解反应的主反应路径以R3及R4为主;该热解反应得到的最终产物有3-4,二羟基甲苯、对羟基甲苯、2-乙烯-4-甲基-3,5-二烯环己酮、甲烷、甲醇及甲醛。 相似文献
79.
80.