全文获取类型
收费全文 | 676492篇 |
免费 | 16482篇 |
国内免费 | 3327篇 |
专业分类
耳鼻咽喉 | 8842篇 |
儿科学 | 14201篇 |
妇产科学 | 10990篇 |
基础医学 | 98079篇 |
口腔科学 | 16584篇 |
临床医学 | 56758篇 |
内科学 | 104841篇 |
皮肤病学 | 8778篇 |
神经病学 | 59714篇 |
特种医学 | 34720篇 |
外国民族医学 | 7篇 |
外科学 | 86540篇 |
综合类 | 9993篇 |
现状与发展 | 6篇 |
一般理论 | 271篇 |
预防医学 | 53710篇 |
眼科学 | 12456篇 |
药学 | 69915篇 |
4篇 | |
中国医学 | 5575篇 |
肿瘤学 | 44317篇 |
出版年
2023年 | 6392篇 |
2022年 | 10216篇 |
2021年 | 13371篇 |
2020年 | 14080篇 |
2019年 | 10146篇 |
2018年 | 7239篇 |
2017年 | 6903篇 |
2016年 | 7571篇 |
2015年 | 14101篇 |
2014年 | 27251篇 |
2013年 | 27654篇 |
2012年 | 33310篇 |
2011年 | 34372篇 |
2010年 | 26496篇 |
2009年 | 27722篇 |
2008年 | 36701篇 |
2007年 | 38917篇 |
2006年 | 39193篇 |
2005年 | 38858篇 |
2004年 | 36457篇 |
2003年 | 34441篇 |
2002年 | 33796篇 |
2001年 | 33144篇 |
2000年 | 29652篇 |
1999年 | 24150篇 |
1998年 | 8723篇 |
1997年 | 6505篇 |
1996年 | 6269篇 |
1995年 | 5492篇 |
1994年 | 4654篇 |
1993年 | 3928篇 |
1992年 | 9599篇 |
1991年 | 8203篇 |
1990年 | 6997篇 |
1989年 | 5689篇 |
1988年 | 4693篇 |
1987年 | 2249篇 |
1986年 | 1186篇 |
1985年 | 1524篇 |
1984年 | 1421篇 |
1983年 | 1074篇 |
1982年 | 996篇 |
1981年 | 869篇 |
1980年 | 837篇 |
1979年 | 651篇 |
1978年 | 520篇 |
1977年 | 476篇 |
1976年 | 327篇 |
1975年 | 221篇 |
1974年 | 174篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
《Journal of pharmaceutical sciences》2023,112(1):225-229
Cocrystallization is a technique for improving the physical properties of active pharmaceutical ingredients. However, cocrystals can transform into more stable polymorphs as well as dissociate to original materials. Therefore, an analytical technique is required to determine the polymorphic transformation quickly and accurately in tablets. The purpose of this study is to develop a method to monitor cocrystal polymorphs in model tablets using transmission low-frequency Raman spectroscopy. The tablets, consisting of only metastable polymorphs of caffeine-glutaric acid cocrystals, were stored under various relative humidity levels. The composition of the cocrystal polymorphs were calculated from a calibration curve relating the actual composition to the predicted values calculated by partial least squares regression processing of low-frequency Raman spectra. The metastable form gradually converted to a stable form, and polymorphic phase transformation occurred with increasing relative humidity. Ninety-six percent of the metastable form converted into a stable form stored at 25 °C after 3 h at 95% RH. In conclusion, transmission low-frequency Raman spectroscopy can be used to quantitatively monitor cocrystal polymorphs. This technique is one of the candidate techniques to quantifiably evaluate the physico-chemical stability of cocrystal polymorphs in tablets. 相似文献
4.
5.
6.
7.
8.
Although methadone is effective in the management of acute pain, the complexity of its absorption-distribution-metabolism-excretion profile limits its use as an opioid of choice for perioperative analgesia. Because deuteration is known to improve the pharmacokinetic, pharmacodynamic and toxicological properties of some drugs, here we characterized the single dose pharmacokinetic properties and post-operative analgesic efficacy of d9-methadone.The pharmacokinetic profiles of d9-methadone and methadone administered intravenously to CD-1 male mice revealed that deuteration leads to a 5.7- and 4.4-fold increase in the area under the time-concentration curve and maximum concentration in plasma, respectively, as well as reduction in clearance (0.9 ± 0.3 L/h/kg vs 4.7 ± 0.8 L/h/kg). The lower brain-to-plasma ratio of d9-methadone compared to that of methadone (0.35 ± 0.12 vs 2.05 ± 0.62) suggested that deuteration decreases the transfer of the drug across the blood-brain barrier. The estimated LD50 value for a single intravenous dose of d9-methadone was 2.1-fold higher than that for methadone. Moreover, d9-methadone outperformed methadone in the efficacy against postoperative pain by primarily activating peripheral opioid receptors. Collectively, these data suggest that the replacement of three hydrogen atoms in three methyl groups of methadone altered its pharmacokinetic properties, improved safety, and enhanced its analgesic efficacy. 相似文献
9.
《Research in social & administrative pharmacy》2022,18(9):3694-3698
In this paper, we argue that understanding and addressing the problem of poor-quality medical products requires a more interdisciplinary approach than has been evident to date. While prospective studies based on rigorous standardized methodologies are the gold standard for measuring the prevalence of poor-quality medical products and understanding their distribution nationally and internationally, they should be complemented by social science research to unpack the complex set of social, economic, and governance factors that underlie these patterns. In the following sections, we discuss specific examples of prospective quality surveys and of social science studies, highlighting the value of cross-sector partnerships in driving high-quality, policy-relevant research in this area. 相似文献
10.