全文获取类型
收费全文 | 570617篇 |
免费 | 5502篇 |
国内免费 | 974篇 |
专业分类
电工技术 | 10412篇 |
综合类 | 721篇 |
化学工业 | 87390篇 |
金属工艺 | 28009篇 |
机械仪表 | 20162篇 |
建筑科学 | 12449篇 |
矿业工程 | 4780篇 |
能源动力 | 12153篇 |
轻工业 | 39642篇 |
水利工程 | 6988篇 |
石油天然气 | 15771篇 |
武器工业 | 34篇 |
无线电 | 60370篇 |
一般工业技术 | 124708篇 |
冶金工业 | 87843篇 |
原子能技术 | 16014篇 |
自动化技术 | 49647篇 |
出版年
2021年 | 4640篇 |
2019年 | 4498篇 |
2018年 | 13160篇 |
2017年 | 13419篇 |
2016年 | 11920篇 |
2015年 | 5506篇 |
2014年 | 9157篇 |
2013年 | 22885篇 |
2012年 | 15240篇 |
2011年 | 22558篇 |
2010年 | 18950篇 |
2009年 | 19767篇 |
2008年 | 20504篇 |
2007年 | 21465篇 |
2006年 | 13999篇 |
2005年 | 14538篇 |
2004年 | 13662篇 |
2003年 | 13238篇 |
2002年 | 12255篇 |
2001年 | 11885篇 |
2000年 | 11536篇 |
1999年 | 11172篇 |
1998年 | 23685篇 |
1997年 | 17766篇 |
1996年 | 13853篇 |
1995年 | 11013篇 |
1994年 | 10124篇 |
1993年 | 10073篇 |
1992年 | 8111篇 |
1991年 | 8024篇 |
1990年 | 7998篇 |
1989年 | 7784篇 |
1988年 | 7535篇 |
1987年 | 6804篇 |
1986年 | 6831篇 |
1985年 | 7691篇 |
1984年 | 7181篇 |
1983年 | 6848篇 |
1982年 | 6253篇 |
1981年 | 6485篇 |
1980年 | 6207篇 |
1979年 | 6331篇 |
1978年 | 6371篇 |
1977年 | 6945篇 |
1976年 | 8424篇 |
1975年 | 5701篇 |
1974年 | 5663篇 |
1973年 | 5725篇 |
1972年 | 4968篇 |
1971年 | 4501篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Valence M. K. Ndesendo Yahya E. Choonara Leith C. R. Meyer Pradeep Kumar Lomas K. Tomar Charu Tyagi 《Drug development and industrial pharmacy》2015,41(8):1274-1287
Context and objective: The aim of this study was to develop, characterize and evaluate a mucoadhesive caplet resulting from a polymeric blend (polymeric caplet) for intravaginal anti-HIV-1 delivery.Materials and methods: Poly(lactic-co-glycolic) acid, ethylcellulose, poly(vinylalcohol), polyacrylic acid and modified polyamide 6, 10 polymers were blended and compressed to a caplet-shaped device, with and without two model drugs 3′-azido-3′-deoxythymidine (AZT) and polystyrene sulfonate (PSS). Thermal analysis, infrared spectroscopy and microscopic analysis were carried out on the caplets employing temperature-modulated DSC (TMDSC), Fourier transform infra-red (FTIR) spectrometer and scanning electron microscope, respectively. In vitro and in vivo drug release analyses as well as the histopathological toxicity studies were carried out on the drug-loaded caplets. Furthermore, molecular mechanics (MM) simulations were carried out on the drug-loaded caplets to corroborate the experimental findings.Results and discussion: There was a big deviation between the Tg of the polymeric caplet from the Tg's of the constituent polymers indicating a strong interaction between constituent polymers. FTIR spectroscopy confirmed the presence of specific ionic and non-ionic interactions within the caplet. A controlled near zero-order drug release was obtained for AZT (20 d) and PSS (28 d). In vivo results, i.e. the drug concentration in plasma ranged between 0.012–0.332?mg/mL and 0.009–0.256?mg/mL for AZT and PSS over 1–28 d.Conclusion: The obtained results, which were corroborated by MM simulations, attested that the developed system has the potential for effective delivery of anti-HIV-agents. 相似文献
62.
63.
64.
65.
Hyperspectral imaging (HSI) is a spectroscopic method that uses densely sampled measurements along the electromagnetic spectrum to identify the unique molecular composition of an object. Traditionally HSI has been associated with remote sensing-type applications, but recently has found increased use in biomedicine, from investigations at the cellular to the tissue level. One of the main challenges in the analysis of HSI is estimating the proportions, also called abundance fractions of each of the molecular signatures. While there is great promise for HSI in the area of biomedicine, large variability in the measurements and artifacts related to the instrumentation has slow adoption into more widespread practice. In this article, we propose a novel regularization and variable selection method called the spatial LASSO (SPLASSO). The SPLASSO incorporates spatial information via a graph Laplacian-based penalty to help improve the model estimation process for multivariate response data. We show the strong performance of this approach on a benchmark HSI dataset with considerable improvement in predictive accuracy over the standard LASSO. Supplementary materials for this article are available online. 相似文献
66.
67.
68.
69.
Verbovitskii Yu. V. Denis R. V. Shtender V. V. Zavalii I. Yu. 《Powder Metallurgy and Metal Ceramics》2015,54(3-4):220-226
Powder Metallurgy and Metal Ceramics - Multiphase La 2 MgNi 9 alloys are synthesized by induction melting. The crystalline structures of all phases in the alloys are determined with X-ray... 相似文献
70.