全文获取类型
收费全文 | 87897篇 |
免费 | 6428篇 |
国内免费 | 3084篇 |
专业分类
电工技术 | 4479篇 |
技术理论 | 9篇 |
综合类 | 4720篇 |
化学工业 | 15729篇 |
金属工艺 | 4549篇 |
机械仪表 | 5309篇 |
建筑科学 | 7187篇 |
矿业工程 | 2109篇 |
能源动力 | 2503篇 |
轻工业 | 4982篇 |
水利工程 | 1482篇 |
石油天然气 | 4620篇 |
武器工业 | 496篇 |
无线电 | 10643篇 |
一般工业技术 | 11446篇 |
冶金工业 | 4748篇 |
原子能技术 | 853篇 |
自动化技术 | 11545篇 |
出版年
2024年 | 344篇 |
2023年 | 1351篇 |
2022年 | 2337篇 |
2021年 | 3191篇 |
2020年 | 2381篇 |
2019年 | 2081篇 |
2018年 | 2295篇 |
2017年 | 2561篇 |
2016年 | 2401篇 |
2015年 | 2997篇 |
2014年 | 4090篇 |
2013年 | 5153篇 |
2012年 | 5322篇 |
2011年 | 5605篇 |
2010年 | 4980篇 |
2009年 | 4794篇 |
2008年 | 4547篇 |
2007年 | 4475篇 |
2006年 | 4728篇 |
2005年 | 4213篇 |
2004年 | 2826篇 |
2003年 | 2528篇 |
2002年 | 2225篇 |
2001年 | 2050篇 |
2000年 | 2330篇 |
1999年 | 2614篇 |
1998年 | 2416篇 |
1997年 | 1924篇 |
1996年 | 1776篇 |
1995年 | 1465篇 |
1994年 | 1230篇 |
1993年 | 890篇 |
1992年 | 669篇 |
1991年 | 550篇 |
1990年 | 423篇 |
1989年 | 377篇 |
1988年 | 327篇 |
1987年 | 177篇 |
1986年 | 166篇 |
1985年 | 112篇 |
1984年 | 100篇 |
1983年 | 63篇 |
1982年 | 60篇 |
1981年 | 54篇 |
1980年 | 38篇 |
1979年 | 32篇 |
1978年 | 13篇 |
1977年 | 33篇 |
1976年 | 16篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
12.
针对区域地面沉降监测点数量有限、分布不均的情况,一般采用空间插值的手段建立表面拟合模型来解决。基于分形插值,采用随机选择迭代函数的思想对传统的趋势面拟合法作出改进,改进后拟合优度系数提高0.03,达到0.995,且改进前后的拟合结果符合显著性检验的要求。实验结果表明:改进前后趋势面拟合法拟合结果满足地面沉降监测的精度要求,改进后方法的拟合优度更高,对现实地面沉降量变化的描绘更加真实,可为沉降灾害评价工作提供更准确的依据。 相似文献
13.
14.
15.
Yao‐Min Hung Neng‐Chyan Huang Jyh‐Seng Wang Shue‐Ren Wann 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(2):344-346
Cases of isolated hepatic tuberculosis (TB) are rare. The diagnosis is often delayed or missed because of nonspecific symptoms and laboratory findings. Besides, the disease is extremely rare even in a country where TB is an alarming public health problem. This report demonstrates the difficulty in correctly diagnosing local hepatic TB. We report the case of a 62‐year‐old male patient with end‐stage renal disease treated with hemodialysis, who developed 2 months of abdominal distension and general anorexia, with hyperechoic hepatic lesions on ultrasound. Computed tomography suspected multiple liver tumors. The liver biopsy finally led to the diagnosis of TB of the liver without other involvements. We conclude that isolated hepatic TB is one of the rare forms of extrapulmonary TB in dialysis patients. A greater awareness of this rare clinical entity may prevent needless surgical interventions. 相似文献
16.
17.
18.
Wei-Li Xie Xiao-Dong Zhang Wen-Hui Liu Qi Xie Guang-Wu Wen Xiao-Xiao Huang Jian-Dong Zhu Fei-Xiang Ma 《稀有金属(英文版)》2019,(3)
SiC nano wires were fabricated on the silicon substrate dipped with a layer of Ni catalyst at 900 ℃ by gas pressure annealing processing. The morphologies and crystal structures were determined by scanning electron microscopy(SEM), transmission electron microscopy(TEM)and X-ray diffraction(XRD). The results show that the assynthesized nanowires are β-SiC single crystalline with diameter range of 50-100 nm, and length of tens of micron by directly annealing at 900 ℃. The SiC nano wires grow along the [111] direction with highly uniform morphology. And the possible growth mechanism of SiC nano wires is proposed.The present work provides an efficient strategy for the production of high-quality SiC nano wires. 相似文献
19.
Dr. Yahu A. Liu Dr. Qihui Jin Qiang Ding Dr. Xueshi Hao Tingting Mo Shanshan Yan Dr. Yefen Zou Dr. Zhihong Huang Xiaoyue Zhang Wenqi Gao Dr. Tom Y.-H. Wu Chun Li Dr. Badry Bursalaya Dr. Michael Di Donato Dr. You-Qing Zhang Lisa Deaton Dr. Weijun Shen Dr. Brandon Taylor Anwesh Kamireddy Dr. George Harb Dr. Jing Li Dr. Yong Jia Dr. Andrew M. Schumacher Dr. Bryan Laffitte Dr. Richard Glynne Dr. Shifeng Pan Dr. Peter McNamara Dr. Valentina Molteni Dr. Jon Loren 《ChemMedChem》2020,15(16):1562-1570
Loss of β-cell mass and function can lead to insufficient insulin levels and ultimately to hyperglycemia and diabetes mellitus. The mainstream treatment approach involves regulation of insulin levels; however, approaches intended to increase β-cell mass are less developed. Promoting β-cell proliferation with low-molecular-weight inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) offers the potential to treat diabetes with oral therapies by restoring β-cell mass, insulin content and glycemic control. GNF4877, a potent dual inhibitor of DYRK1A and glycogen synthase kinase 3β (GSK3β) was previously reported to induce primary human β-cell proliferation in vitro and in vivo. Herein, we describe the lead optimization that lead to the identification of GNF4877 from an aminopyrazine hit identified in a phenotypic high-throughput screening campaign measuring β-cell proliferation. 相似文献
20.
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