全文获取类型
收费全文 | 54764篇 |
免费 | 4918篇 |
国内免费 | 2605篇 |
专业分类
电工技术 | 3367篇 |
技术理论 | 4篇 |
综合类 | 3857篇 |
化学工业 | 8792篇 |
金属工艺 | 3135篇 |
机械仪表 | 3684篇 |
建筑科学 | 4310篇 |
矿业工程 | 1737篇 |
能源动力 | 1561篇 |
轻工业 | 4482篇 |
水利工程 | 1047篇 |
石油天然气 | 3624篇 |
武器工业 | 418篇 |
无线电 | 5771篇 |
一般工业技术 | 6008篇 |
冶金工业 | 2460篇 |
原子能技术 | 619篇 |
自动化技术 | 7411篇 |
出版年
2024年 | 147篇 |
2023年 | 1001篇 |
2022年 | 1598篇 |
2021年 | 2401篇 |
2020年 | 1910篇 |
2019年 | 1506篇 |
2018年 | 1697篇 |
2017年 | 1850篇 |
2016年 | 1631篇 |
2015年 | 2290篇 |
2014年 | 2860篇 |
2013年 | 3408篇 |
2012年 | 3580篇 |
2011年 | 4048篇 |
2010年 | 3447篇 |
2009年 | 3252篇 |
2008年 | 3342篇 |
2007年 | 3077篇 |
2006年 | 3013篇 |
2005年 | 2640篇 |
2004年 | 1730篇 |
2003年 | 1536篇 |
2002年 | 1563篇 |
2001年 | 1363篇 |
2000年 | 1242篇 |
1999年 | 1264篇 |
1998年 | 944篇 |
1997年 | 821篇 |
1996年 | 705篇 |
1995年 | 598篇 |
1994年 | 503篇 |
1993年 | 338篇 |
1992年 | 282篇 |
1991年 | 168篇 |
1990年 | 144篇 |
1989年 | 93篇 |
1988年 | 84篇 |
1987年 | 63篇 |
1986年 | 37篇 |
1985年 | 24篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 13篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1959年 | 3篇 |
1953年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Amphotericin B (AMB) was often used in intra-articular injection administration for fungal arthritis, because it could often bring a satisfactory therapeutic efficacy and a minimum systemic toxic side effect. However, because of the multiple operations and the frequent injections, the compliance of the patients was bad. Therefore, to develop a long-term sustained-released preparation of AMB for mycotic arthritis intra-articular administration is of great significance. The purpose of present study was to develop a long-term sustained-released in situ gel of a water-insoluble drug AMB for mycotic arthritis intra-articular administration. Based on the evaluations of the in vitro properties of the formulations, the formulation containing 10% (w/w) ethanol, 15% (w/w) PG, 0.75% (w/w) HA, 5% (w/w) purified soybean oil, 0.03% (w/w) α-tocopherol, 15% (w/w) water and 55% (w/w) glyceryl monooleate was selected as a suitable intra-articular injectable in situ gel drug delivery system for water-insoluble drug AMB. Furthermore, the results of the in vivo study on rabbits showed that the selected formulation was a safe and effective long-term sustained-released intra-articular injectable AMB preparation. Therefore, the presented in situ AMB gel could reduce the frequency of the administration in the AMB treatment of fungal arthritis, and then would get a good patient compliance. 相似文献
23.
24.
Chenxu Liu Shuguang Zhang Ruonan Ji Peng Wang Jin Zhang Yu Tian Yonggang Meng Yedong He 《Ceramics International》2019,45(4):4747-4755
Semiconductor particles doped Al2O3 coatings were prepared by cathode plasma electrolytic deposition in Al(NO3)3 electrolyte dispersed with SiC micro- and nano-particles (average particle sizes of 0.5–1.7?µm and 40?nm respectively). The effects of the concentrations and particle sizes of the SiC on the microstructures and tribological performances of the composite coatings were studied. In comparison with the case of dispersing with SiC microparticles, the dispersion of SiC nanoparticles in the coatings was more uniform. When the concentration of SiC nanoparticles was 5?g/L, the surface roughness of the composite coating was reduced by 63%, compared with that of the unmodified coating. Friction results demonstrated that the addition of 5?g/L SiC nanoparticles reduced the friction coefficient from 0.60 to 0.38 and decreased the wear volume under dry friction. The current density and bath voltage were measured to analyze the effects of SiC particles on the deposition process. The results showed that the SiC particles could alter the electrical behavior of the coatings during the deposition process, weaken the bombardment of the plasma, and improve the structures of the coatings. 相似文献
25.
26.
Rui ZHAO Weikai LI Tian WANG Ke ZHAN Zheng YANG Ya YAN Bin ZHAO Junhe YANG 《材料科学前沿(英文版)》2020,14(2):188
Effective thermal management of electronic integrated devices with high powder density has become a serious issue, which requires materials with high thermal conductivity (TC). In order to solve the problem of weak bonding between graphite and Cu, a novel Cu/graphite film/Cu sandwich composite (Cu/GF/Cu composite) with ultrahigh TC was fabricated by electro-deposition. The micro-riveting structure was introduced to enhance the bonding strength between graphite film and deposited Cu layers by preparing a rectangular array of micro-holes on the graphite film before electro-deposition. TC and mechanical properties of the composites with different graphite volume fractions and current densities were investigated. The results showed that the TC enhancement generated by the micro-riveting structure for Cu/GF/Cu composites at low graphite content was more effective than that at high graphite content, and the strong texture orientation of deposited Cu resulted in high TC. Under the optimizing preparing condition, the highest in-plane TC reached 824.3 W·m−1·K−1, while the ultimate tensile strength of this composite was about four times higher than that of the graphite film. 相似文献
27.
秦泰峰 《石油化工管理干部学院学报》2015,(2):64-69
在中国企业国际化背景下,本文以石油贸易公司为例,研究其绩效考核体系,重点放在全流程管控上,从职责分工、计划制定、考核维度、评分标准和强制等级分布等方面对绩效考核进行研究,提出涵盖所有员工的国际化考核体系,以期通过实现公司内部管理体系的完整,以更好地适应国际竞争。 相似文献
28.
以中低温煤焦油沥青质为原料,采用NiMoW/γ-Al_2O_3商业催化剂,在反应温度380℃、反应压力8 MPa和反应时间1.5 h条件下,分别在不同剂油质量比(1∶25、1∶20、1∶15、1∶10)条件下进行加氢实验,通过采用元素分析、FT-IR、XRD、~1H-NMR和XPS等分析表征手段,考察不同剂油质量比对中低温煤焦油沥青质加氢转化过程的影响。结果表明,随着剂油质量比的增加,沥青质转化率提高,加氢产物分布也发生大幅变化,沥青质和芳香分轻质化转化为饱和分。但随着剂油质量比的进一步提高,同时也发生了更多的裂化反应和缩合反应,剂油质量比在合适范围能够很好地起到加氢轻质化且抑制结焦的效果。 相似文献
29.
30.
Yude Ji Yanping Guo Yuejuan Liu Yun Tian 《International Journal of Adaptive Control and Signal Processing》2020,34(3):283-297
This article focuses on the consensus problem of leader-following fractional-order multi-agent systems (MASs) with general linear and Lipschitz nonlinear dynamics. First, the distributed adaptive protocols for linear and nonlinear fractional-order MASs are constructed, respectively. We allow the control coupling gains to be time varying for each agent. Moreover, the adaptive modification schemes for the control gain are designed, which renders smaller control gains and thus requires smaller amplitude on the control input without sacrificing consensus convergence. Second, based on fractional-order Lyapunov stability theorem and Barbalat's lemma, two novel sufficient conditions in terms of linear matrix inequalities are provided to ensure that the leader-following consensus can be obtained in the case for any undirected connected communication graph. Furthermore, we show that the proposed algorithm also works for consensus of agents with intrinsic Lipschitz nonlinear dynamics. As a result, the proposed framework requires no global information and thus can be implemented in a fully distributed manner. Finally, the numerical simulations are given to demonstrate the effectiveness of obtained the theoretical results. 相似文献