全文获取类型
收费全文 | 2628篇 |
免费 | 34篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 52篇 |
综合类 | 2篇 |
化学工业 | 507篇 |
金属工艺 | 134篇 |
机械仪表 | 128篇 |
建筑科学 | 30篇 |
矿业工程 | 40篇 |
能源动力 | 18篇 |
轻工业 | 21篇 |
水利工程 | 35篇 |
石油天然气 | 128篇 |
武器工业 | 4篇 |
无线电 | 197篇 |
一般工业技术 | 686篇 |
冶金工业 | 368篇 |
原子能技术 | 221篇 |
自动化技术 | 97篇 |
出版年
2022年 | 36篇 |
2021年 | 42篇 |
2020年 | 52篇 |
2019年 | 54篇 |
2018年 | 89篇 |
2017年 | 85篇 |
2016年 | 101篇 |
2015年 | 48篇 |
2014年 | 72篇 |
2013年 | 82篇 |
2012年 | 95篇 |
2011年 | 93篇 |
2010年 | 101篇 |
2009年 | 85篇 |
2008年 | 93篇 |
2007年 | 90篇 |
2006年 | 75篇 |
2005年 | 47篇 |
2004年 | 59篇 |
2003年 | 61篇 |
2002年 | 44篇 |
2001年 | 32篇 |
2000年 | 34篇 |
1999年 | 32篇 |
1998年 | 42篇 |
1997年 | 37篇 |
1996年 | 41篇 |
1995年 | 29篇 |
1993年 | 28篇 |
1992年 | 29篇 |
1991年 | 32篇 |
1990年 | 27篇 |
1989年 | 29篇 |
1988年 | 28篇 |
1987年 | 27篇 |
1986年 | 26篇 |
1985年 | 34篇 |
1984年 | 34篇 |
1982年 | 34篇 |
1981年 | 32篇 |
1980年 | 31篇 |
1979年 | 29篇 |
1978年 | 26篇 |
1977年 | 34篇 |
1976年 | 39篇 |
1975年 | 29篇 |
1973年 | 40篇 |
1972年 | 31篇 |
1971年 | 33篇 |
1968年 | 26篇 |
排序方式: 共有2668条查询结果,搜索用时 15 毫秒
51.
E. S. Gorkunov R. A. Savrai A. V. Makarov S. M. Zadvorkin S. V. Smirnov S. A. Rogovaya M. N. Solomein 《Russian Journal of Nondestructive Testing》2006,42(5):309-314
The influence of cyclic loading of annealed steel 45 during low-cycle fatigue on changes in its magnetic characteristics, in particular, the coercive force and the residual magnetic induction, for the major and minor magnetic-hysteresis loops and on changes in the propagation velocity of a longitudinal acoustic wave is studied. The sensitivity of the considered physical characteristics to the value of plastic deformation stored under cyclic loading in the region of both large and small strains is determined. The residual mechanical properties displayed after cyclic loading are determined, and the steady-state correlations between the coercive force measured on minor hysteresis loops in weak fields (the Rayleigh region) and the remanent clongation are obtained. The possibility of monitoring the stored plastic deformation and assessing the residual life of a material during its cyclic loading from the values of its magnetic parameters is shown. 相似文献
52.
Yury Chesnokov Andrey Mozhaev Roman Kamyshinsky Alexander Gordienko Liubov Dadinova 《International journal of molecular sciences》2022,23(10)
Dps (DNA-binding protein from starved cells) is well known for the structural protection of bacterial DNA by the formation of highly ordered intracellular assemblies under stress conditions. Moreover, this ferritin-like protein can perform fast oxidation of ferrous ions and subsequently accumulate clusters of ferric ions in its nanocages, thus providing the bacterium with physical and chemical protection. Here, cryo-electron microscopy was used to study the accumulation of iron ions in the nanocage of a Dps protein from Escherichia coli. We demonstrate that Fe2+ concentration in the solution and incubation time have an insignificant effect on the volume and the morphology of iron minerals formed in Dps nanocages. However, an increase in the Fe2+ level leads to an increase in the proportion of larger clusters and the clusters themselves are composed of discrete ~1–1.5 nm subunits. 相似文献
53.
Vitaly Shubin Yury Shelygin Sergey Achkasov Oleg Sushkov Ilya Nazarov Alexey Ponomarenko Iuliia Alimova Anna Loginova Aleksey Tsukanov 《International journal of molecular sciences》2022,23(13)
The aim of this study was to determine the characteristics of Russian patients with microsatellite instability (MSI) tumors. MSI in the tumor was determined in 514 patients with colon cancer using PCR and subsequent fragment analysis for five markers (NR21, NR24, BAT25, BAT26, and NR27). In the presence of microsatellite instability, the mismatch repair (MMR) system genes were examined using the NGS and MLPA methods to establish the diagnosis of Lynch syndrome. The overall frequency of MSI tumors was 15%: at stage I—19% (9/48), at stage II—21% (44/213), at stage III—16% (26/160), and at stage IV—2% (2/93). Patients with MSI tumors differed in the age of diagnosis, tumor localization, time of cancer recurrence, and stage of the disease. The overall and disease-free survival of patients whose tumors had MSI status was higher than that of patients with microsatellite-stable status, p = 0.04 and p = 0.02, respectively. Analysis of overall and disease-free survival of patients with Lynch syndrome and patients with sporadic colon cancer, but with MSI status, did not reveal significant differences, p = 0.52 and p = 0.24, respectively. The age of patients with Lynch syndrome was significantly younger than that of patients with sporadic colon cancer whose tumors had MSI status (p < 0.001). 相似文献
54.
Erkan Aydin Michele De Bastiani Xinbo Yang Muhammad Sajjad Faisal Aljamaan Yury Smirnov Mohamed Nejib Hedhili Wenzhu Liu Thomas G. Allen Lujia Xu Emmanuel Van Kerschaver Monica Morales‐Masis Udo Schwingenschlgl Stefaan De Wolf 《Advanced functional materials》2019,29(25)
Parasitic absorption in transparent electrodes is one of the main roadblocks to enabling power conversion efficiencies (PCEs) for perovskite‐based tandem solar cells beyond 30%. To reduce such losses and maximize light coupling, the broadband transparency of such electrodes should be improved, especially at the front of the device. Here, the excellent properties of Zr‐doped indium oxide (IZRO) transparent electrodes for such applications, with improved near‐infrared (NIR) response, compared to conventional tin‐doped indium oxide (ITO) electrodes, are shown. Optimized IZRO films feature a very high electron mobility (up to ≈77 cm2 V?1 s?1), enabling highly infrared transparent films with a very low sheet resistance (≈18 Ω □?1 for annealed 100 nm films). For devices, this translates in a parasitic absorption of only ≈5% for IZRO within the solar spectrum (250–2500 nm range), to be compared with ≈10% for commercial ITO. Fundamentally, it is found that the high conductivity of annealed IZRO films is directly linked to promoted crystallinity of the indium oxide (In2O3) films due to Zr‐doping. Overall, on a four‐terminal perovskite/silicon tandem device level, an absolute 3.5 mA cm?2 short‐circuit current improvement in silicon bottom cells is obtained by replacing commercial ITO electrodes with IZRO, resulting in improving the PCE from 23.3% to 26.2%. 相似文献
55.
Layered Orthorhombic Nb2O5@Nb4C3Tx and TiO2@Ti3C2Tx Hierarchical Composites for High Performance Li‐ion Batteries 下载免费PDF全文
Chuanfang Zhang Seon Joon Kim Michael Ghidiu Meng‐Qiang Zhao Michel W. Barsoum Valeria Nicolosi Yury Gogotsi 《Advanced functional materials》2016,26(23):4143-4151
Engineering electrode nanostructures is critical in developing high‐capacity, fast rate‐response, and safe Li‐ion batteries. This study demonstrates the synthesis of orthorhombic Nb2O5@Nb4C3Tx (or @Nb2CTx) hierarchical composites via a one‐step oxidation —in flowing CO2 at 850 °C —of 2D Nb4C3Tx (or Nb2CTx) MXene. The composites possess a layered architecture with orthorhombic Nb2O5 nanoparticles decorated uniformly on the surface of the MXene flakes and interconnected by disordered carbon. The composites have a capacity of 208 mAh g?1 at a rate of 50 mA g?1 (0.25 C) in 1–3 V versus Li+/Li, and retain 94% of the specific capacity with 100% Coulombic efficiency after 400 cycles. The good electrochemical performances could be attributed to three synergistic effects: (1) the high conductivity of the interior, unoxidized Nb4C3Tx layers, (2) the fast rate response and high capacity of the external Nb2O5 nanoparticles, and (3) the electron “bridge” effects of the disordered carbon. This oxidation method was successfully extended to Ti3C2Tx and Nb2CTx MXenes to prepare corresponding composites with similar hierarchical structures. Since this is an early report on producing this structure, there is much room to push the boundaries further and achieve better electrochemical performance. 相似文献
56.
Results of comparisons of standard instruments that are components of the state standard of the unit of pressure for the region of variable pressures (GET 131–81) are presented. The reliability of the results of comparisons of the instruments with the declared uncertainties and the reproducibility of the unit of pressure are demonstrated. 相似文献
57.
A procedure is proposed to construct semantic diagram models for the electrolysis on a solid cathode in a salt halide melt under potentiostatic conditions. These models are intended to identify the static states of the system that correspond to a certain combination of the processes occurring on an electrode and in the system volume. Examples for discharging of univalent and polyvalent metals are given. 相似文献
58.
High-purity single-crystal W and W??Nb?? have been prepared using chemical vapor transport. The impurity composition of the materials has been determined using spark source mass spectrometry and high-temperature vacuum extraction. The radial Nb profile in the alloy has been investigated by electron microscopy. 相似文献
59.
Ongoing control of the transverse thickness fluctuation of cold-rolled high-strength strip 总被引:1,自引:0,他引:1
Minimization of the transverse thickness fluctuation is considered, in the production of cold-rolled strip from a blank of
multiple-strip width on a five-cell 630 mill. The forces and torques in the multipass rolling of strip produced from intermediate
strip with an asymmetric cross section are determined. 相似文献
60.
In this paper, we study stabilizing controllers for time varying bilinear systems. Here, the feedback function, f in our paper is for larger classes than those given in the current literature. We establish existence theorems for stabilizing bilinear systems by output feedback from a large class. The main theorems basically state that under broad conditions, the zero state of the systems can be made asymptotically stable by output feedback. Following these stabilizing theorems, a new design procedure for the feedback control law is presented. Application of the new theorems is illustrated by a simulation example. 相似文献