全文获取类型
收费全文 | 20226篇 |
免费 | 2018篇 |
国内免费 | 1070篇 |
专业分类
电工技术 | 978篇 |
综合类 | 1223篇 |
化学工业 | 6141篇 |
金属工艺 | 1725篇 |
机械仪表 | 862篇 |
建筑科学 | 633篇 |
矿业工程 | 521篇 |
能源动力 | 1143篇 |
轻工业 | 2107篇 |
水利工程 | 124篇 |
石油天然气 | 920篇 |
武器工业 | 570篇 |
无线电 | 1482篇 |
一般工业技术 | 2562篇 |
冶金工业 | 1398篇 |
原子能技术 | 240篇 |
自动化技术 | 685篇 |
出版年
2024年 | 72篇 |
2023年 | 451篇 |
2022年 | 524篇 |
2021年 | 716篇 |
2020年 | 700篇 |
2019年 | 673篇 |
2018年 | 595篇 |
2017年 | 748篇 |
2016年 | 727篇 |
2015年 | 696篇 |
2014年 | 1047篇 |
2013年 | 1137篇 |
2012年 | 1261篇 |
2011年 | 1339篇 |
2010年 | 1055篇 |
2009年 | 1027篇 |
2008年 | 893篇 |
2007年 | 1215篇 |
2006年 | 1224篇 |
2005年 | 1115篇 |
2004年 | 986篇 |
2003年 | 866篇 |
2002年 | 798篇 |
2001年 | 644篇 |
2000年 | 575篇 |
1999年 | 444篇 |
1998年 | 328篇 |
1997年 | 279篇 |
1996年 | 231篇 |
1995年 | 177篇 |
1994年 | 171篇 |
1993年 | 114篇 |
1992年 | 117篇 |
1991年 | 82篇 |
1990年 | 63篇 |
1989年 | 54篇 |
1988年 | 36篇 |
1987年 | 27篇 |
1986年 | 13篇 |
1985年 | 22篇 |
1984年 | 19篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
该研究建立了一种亲水交互作用色谱-串联质谱(HILIC-MS/MS)法测定动物源运动食品中潮霉素B、新霉素、安普霉素3种氨基糖苷类抗生素残留量的方法。结果表明,样品经Sielc Obelisc R柱分离,采用0.1%甲酸水溶液-乙腈梯度洗脱,可以实现3种目标物组分的分离。在此条件下,3种氨基糖苷类抗生素在5~500 ng/mL的质量浓度范围内线性关系良好,相关系数R2为0.999 5~0.999 9,检出限均为15 μg/kg,定量限均为50 μg/kg,保留时间的日间和日内相对标准偏差(RSD)分别为3.5%~7.9%和3.5%~4.1%,峰面积的日间和日内RSD分别为3.6%~7.4%和3.2%~3.9%,加标回收率为85.7%~93.6%,回收率试验结果的RSD为3.1%~5.2%。该方法可以满足动物源运动食品中3种氨基糖苷类抗生素的检测需求。 相似文献
12.
Weigang Liang Beibei Wang Guofeng Shen Suzhen Cao Bertrand Mcswain Ning Qin Liyun Zhao Dongmei Yu Jicheng Gong Shanshan Zhao Yawei Zhang Xiaoli Duan 《Indoor air》2020,30(2):264-274
Stunting adversely affects physical and mental outcomes of children. It has not been examined whether household air pollution from solid fuel combustion is a risk factor for stunting in children. In a total of 41,439 children aged 6-17 across China, height was measured using a unified protocol. Multivariable linear regression models and logistic regression models were used to assess the associations of solid fuel use for cooking/heating with stunting in children. Adjusted for covariates, cooking/heating with solid fuel was significantly associated with a lower z-score for height for age and sex (β = −0.21 [−0.32 to −0.09] and −0.17 [−0.31 to −0.03], respectively) and an increased risk of stunting with an estimated ORs of 1.34 [1.07~1.68] and 1.37 [1.02~1.83], respectively. The risk of stunting associated with solid fuel use was statistically significant in high-age children. And the effect was greater on girls than on boys, though the difference was not statistically significant. Our study suggested that Chinese children living in households using solid fuel had a significantly higher risk of stunting than those living in households using cleaner fuel. 相似文献
13.
Covalent triazine frameworks (CTFs) have been recently employed for visible light-driven photocatalysis due to their unique optical and electronic properties. However, the usually highly hydrophobic nature of CTFs, which originates from their overall aromatic backbone, leads to limitations of CTFs for applications in aqueous media. In this study, we aim to extend the range of the application media of CTFs and design hybrid material of a CTF and mesoporous silica (SBA-15) for efficient photocatalysis in aqueous medium. A thiophene-containing CTF was directly synthesized in mesopores of SBA-15. Due to the high surface area and the added hydrophilic properties by silica, the hybrid material demonstrated excellent adsorption of organic molecules in water. This leads not only to high photocatalytic performance of the hybrid material for the degradation of organic dyes in water, but also for efficient photocatalysis in solvent-free and solid state. Furthermore, the reusability, stability and easy recovery of the hybrid material offers promising metal-free heterogeneous photocatalyst for broader applications in different reaction media. 相似文献
14.
Journal of Computer Science and Technology - New non-volatile memory (NVM) technologies are expected to replace main memory DRAM (dynamic random access memory) in the near future. NAND flash... 相似文献
15.
O.N. Kondrateva G.E. Nikiforova A.V. Tyurin M.A. Ryumin V.M. Gurevich A.P. Kritskaya K.S. Gavrichev 《Ceramics International》2018,44(15):18103-18107
The heat capacity of ytterbium orthovanadate was first measured by adiabatic calorimetry in the temperature range T?=?12.28–344.06?K. No obvious anomalies were observed on the curve obtained. The values of standard thermodynamic functions in the temperature range T?=?0–400 K were calculated. Based on low-temperature calorimetry data obtained, previously published data on the high-temperature heat capacity of ytterbium orthovanadate were corrected. The anomalous contribution to heat capacity for YbVO4 was compared with the data known for YbPO4. 相似文献
16.
Andrea Bedon Jean Paul Viricelle Mathilde Rieu Simone Mascotto Antonella Glisenti 《International Journal of Hydrogen Energy》2021,46(27):14735-14747
In this contribution brownmillerite-based nanocomposite cathode for Single-Chamber Solid Oxide Fuel Cells is developed. These cells can be very attractive especially for small and cheap devices because of the absence of seals. The efficiency of SC-SOFCs is strictly connected to the selectivity of anode and cathode, the bottleneck for this technology. The development of a cathode inert in fuel oxidation is particularly challenging. Our strategy is to start from a catalytically un-active support (CFA = Ca2FeAl0.95Mg0.05O5) and induce the formation of iron oxide based nanoparticles, expected to activate oxygen. Symmetric (CFA + FeOx/CGO/CFA + FeOx) and complete cells (CFA + FeOx/CGO/Ni-CGO) are studied in air and methane/oxygen 2:1 mixture. The Area Specific Resistance of CFA + FeOx is less than 1/3 that of CFA. The high selectivity allows to reach an efficiency of 25%; power still needs to be increased but we demonstrated the possibility to develop selective low cost electrodes. The effect of air, methane/oxygen exposure and the heat treatments were carefully investigated. 相似文献
17.
Mechanical behavior of a two-dimensional elastoplastic solid with rectilinear cracks is investigated. Plastic strip model is used to reduce plasticity problem to the equivalent linear elasticity formulation. Two realizations of the mixed mode plastic strip model are considered: in-line plastic strips as proposed by Becker and Gross [Int. J. Fract. 37 (1988) 163], and inclined plastic strips of Panasyuk and Savruk [Appl. Mech. Rev. 47 (1994) 151]. The effective mechanical response predictions are based on the procedure presented in Kachanov et al., [Appl. Mech. Rev. 47 (1994) 151]. Stress-strain relations are obtained for parallel and randomly oriented non-interacting cracks. Results are compared with known elastic solutions. 相似文献
18.
19.
采用丙二酸作为连接,针9-蒽甲醇连接到硅胶上生成硅胶固载的光敏剂。利用此因相光敏剂分别在乙醇和甲苯溶液中敏化反式维生素D3。实验结果表明,此固相光敏剂能够有效地敏化反式维生素D3为顺式维生素D3的反应,并且非常容易从反应体系中分离出来。 相似文献
20.