全文获取类型
收费全文 | 14185篇 |
免费 | 1140篇 |
国内免费 | 43篇 |
专业分类
电工技术 | 241篇 |
综合类 | 19篇 |
化学工业 | 3146篇 |
金属工艺 | 582篇 |
机械仪表 | 809篇 |
建筑科学 | 247篇 |
矿业工程 | 4篇 |
能源动力 | 665篇 |
轻工业 | 1399篇 |
水利工程 | 52篇 |
石油天然气 | 12篇 |
武器工业 | 3篇 |
无线电 | 2365篇 |
一般工业技术 | 3393篇 |
冶金工业 | 891篇 |
原子能技术 | 144篇 |
自动化技术 | 1396篇 |
出版年
2023年 | 185篇 |
2022年 | 104篇 |
2021年 | 435篇 |
2020年 | 365篇 |
2019年 | 368篇 |
2018年 | 492篇 |
2017年 | 515篇 |
2016年 | 605篇 |
2015年 | 504篇 |
2014年 | 712篇 |
2013年 | 973篇 |
2012年 | 1066篇 |
2011年 | 1286篇 |
2010年 | 914篇 |
2009年 | 929篇 |
2008年 | 798篇 |
2007年 | 685篇 |
2006年 | 560篇 |
2005年 | 471篇 |
2004年 | 435篇 |
2003年 | 382篇 |
2002年 | 320篇 |
2001年 | 258篇 |
2000年 | 243篇 |
1999年 | 211篇 |
1998年 | 356篇 |
1997年 | 230篇 |
1996年 | 185篇 |
1995年 | 135篇 |
1994年 | 108篇 |
1993年 | 94篇 |
1992年 | 62篇 |
1991年 | 41篇 |
1990年 | 44篇 |
1989年 | 44篇 |
1988年 | 33篇 |
1987年 | 25篇 |
1986年 | 26篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 17篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1977年 | 11篇 |
1976年 | 15篇 |
1974年 | 7篇 |
1971年 | 6篇 |
1970年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Aluminum, used as a material for heat exchangers in air conditioners, often has problems of leakage of refrigerant on the Al surface due to corrosion. The problems originate from pitting corrosion of the Al in an external environment. To understand corrosion problems, it is necessary to study the corrosion behavior of Al in various environments. In this study, the effects of environmental factors on the corrosion behavior of Al were studied by the surface analysis and electrochemical testing in 3.5 wt% NaCl solutions, with changes of dissolved oxygen, temperature, and concentration of Cl− and S ions. Among the external environmental factors, the presence of oxygen and the increase of Cl− ion concentration do not significantly affect the corrosion potential of Al, leading to an increase of only 1.1 and 6 times, respectively. There was a significant decrease in the corrosion resistance of Al, approximately 40 and 800 times, respectively, with the increase of concentration of S and temperature. 相似文献
2.
Automatic spacing in Korean is used to correct spacing units in a given input sentence. The demand for automatic spacing has been increasing owing to frequent incorrect spacing in recent media, such as the Internet and mobile networks. Therefore, herein, we propose a transformer encoder that reads a sentence bidirectionally and can be pretrained using an out-of-task corpus. Notably, our model exhibited the highest character accuracy (98.42%) among the existing automatic spacing models for Korean. We experimentally validated the effectiveness of bidirectional encoding and pretraining for automatic spacing in Korean. Moreover, we conclude that pretraining is more important than fine-tuning and data size. 相似文献
3.
Jang Hyun-Joo Lee Hyun-Jin Yoon Dong-Kyu Ji Da-Som Kim Ji-Han Lee Chi-Ho 《Food science and biotechnology》2018,27(1):219-225
Food Science and Biotechnology - This study aims to investigate antioxidative and antibacterial properties of fresh garlic (non-aged, NG) and aged garlic (AG) by-products extracted with distilled... 相似文献
4.
Yoon Hyuk Kim Batbayar Khuyagbaatar Kyungsoo Kim 《Journal of Mechanical Science and Technology》2018,32(1):1-10
The human cervical spine is a complex structure that is the most frequently injured site among all spinal injuries. Therefore, understanding of the cervical spine injury and dysfunction, and also biomechanical response to external stimuli is important. Finite element (FE) modeling can help researchers to access the internal stresses and strains in the bones, ligaments and soft tissues more realistically, and it has been widely adopted for spine biomechanics research. Although in recent years numerous techniques have been developed, there are no recent literature reviews on FE models of the cervical spine. Our objective was to present recent advances in FE modeling of the human cervical spine in terms of component modeling, material properties, and validation procedures. Model applications and further development are also discussed. The integration of new technologies will allow us to generate more accurate and comprehensive model of the cervical spine, which can increase efficiency and model applicability. Finally, the FE modeling can help to facilitate diagnosis, treatment, and prevention technologies for cervical spine injuries. 相似文献
5.
6.
An extensive evaluation of low-cost dust sensors was performed using an exponentially decaying particle concentration. A total of 264 sensors including 27 sensors with light-emitting diodes (LEDs) and 237 sensors with laser lighting sources were tested. Those tested sensors were classified into 4 groups based on the deviation from the reference data obtained by a reference instrument. The response linearities of all the tested samples for PM1, PM2.5, and PM10 were in excellent agreement with the reference instrument, except a few samples. For the measurements of PM1 and PM2.5, the lighting source, that is, LED or laser, did not show any significant difference in overall sensor performance. However, LED-based sensors did not perform well for PM10 measurements. The 32, 24, and 16% of all the tested sensors for PM1, PM2.5, and PM10 measurement, respectively, are in the category of Class 1 (reference instrument reading ± 20%) requirement. The performance of the low-cost dust sensors for PM10 measurement was relatively less satisfactory. 相似文献
7.
Sharat Chandra Barman Md. Abu Zahed Md. Sharifuzzaman Seok Gyu Ko Hyosang Yoon Joong San Nah Xing Xuan Jae Yeong Park 《Advanced functional materials》2020,30(14)
Current immunosensors have an insufficient number of binding sites for the recognition of biomolecules, which leads to false positive or negative results. In this research, a facile, cost‐effective, disposable, and highly selective electrochemical immunosensing platform is developed based on cationic polyelectrolyte polyallylamine (PAAMI) anchored laser‐ablated graphene (LAG). Here, for the first time, PAAMI is introduced to stabilize LAG flakes, while retaining the intrinsic thermal and electronic properties of the substrate by noncovalent π–π interaction and electrostatic physical absorption. The sensing platform offers a suitable number of anchoring sites for the immobilized antibodies by providing ? NH2 functional groups. The proper grafting of PAAMI is confirmed through X‐ray photoelectron spectroscopy and Raman spectroscopy. The immunosensing platform is applied to detect immunoglobulin (IgG) biomarkers as a proof of concept. Under optimized conditions, the sensing platform exhibits a linear range of 0.012–15 and 15–352 ng mL?1 with a limit of detection of 6 pg mL?1 for IgG detection with high selectivity. Based on the analysis, the developed immunosensing platform can be used for point‐of‐care detection of IgG in clinical diagnostic centers. Furthermore, the developed strategy is well suited for the detection of other cancer biomarkers after immobilizing the relevant antibodies. 相似文献
8.
Na Yoon Choi 《Journal of Nuclear Science and Technology》2019,56(1):41-54
ABSTRACTIn order to develop a methodology to guarantee the conformance to operational discharge limits for liquid effluent from a NPP at an early stage of design, a risk-informed approach was proposed and its applicability was verified for APR 1400. Existing methodology to calculate risk-based detection limit for a single radionuclide was improved by incorporating a new model to derive more realistic pathway dose factors. A new simple expression was also proposed to adjust risk-based detection limits for multiple radionuclides mixture if necessary. In addition, a new procedure to warrant the compliance with discharge limits by controlling detection limits of only a few principal radionuclides was established in accordance with risk-informed concept. Through case studies for APR 1400 to be commissioned at a hypothetical site, it was shown that calculated pathway dose factors are more realistic for majority of radionuclides. It also turns out that neither present detection limits nor unadjusted risk-based detection limits can be justified when the radionuclide composition is unknown, however further adjustment of detection limits or increasing additional dilution factor resolves the problem. Finally, ten principal radionuclides were identified and shown to be enough for liquid effluent control at APR 1400 from a risk-informed point of view. 相似文献
9.
10.
Kangho Park Woo‐Bin Jung Kiok Kwon Oleg D. Lavrentovich Hee‐Tae Jung 《Advanced functional materials》2019,29(26)
Directed self‐assembly (DSA) using soft materials is an important method for producing periodic nanostructures because it is a simple, cost‐effective process for fabricating high‐resolution patterns. Most of the previously reported DSA methods exploit the self‐assembly of block copolymers, which generates a wide range of nanostructures. In this study, cylinders obtained from supramolecular dendrimer films with a high resolution (<5 nm) exhibit planar ordering over a macroscopic area via guiding topographical templates with a high aspect ratio (>10) and high spatial resolution (≈20 nm) of guiding line patterns. Theoretical and experimental studies reveal that this property is related to geometrical anchoring on the meniscus region and physical surface anchoring on the sidewall. Furthermore, this DSA of dendrimer cylinders is demonstrated by the non‐regular geometry of the patterned template. The macroscopic planar alignment of the dendrimer nanostructure reveals an extremely small feature size (≈4.7 nm) on the wafer scale (>16 cm2). This study is expected to open avenues for the production of a large family of supramolecular dendrimers with different phases and feature dimensions oriented by the DSA approach. 相似文献