全文获取类型
收费全文 | 71812篇 |
免费 | 5026篇 |
国内免费 | 200篇 |
专业分类
耳鼻咽喉 | 529篇 |
儿科学 | 2097篇 |
妇产科学 | 1166篇 |
基础医学 | 9858篇 |
口腔科学 | 1509篇 |
临床医学 | 7550篇 |
内科学 | 15255篇 |
皮肤病学 | 988篇 |
神经病学 | 6835篇 |
特种医学 | 2229篇 |
外国民族医学 | 1篇 |
外科学 | 10072篇 |
综合类 | 880篇 |
一般理论 | 72篇 |
预防医学 | 6394篇 |
眼科学 | 1742篇 |
药学 | 4951篇 |
1篇 | |
中国医学 | 85篇 |
肿瘤学 | 4824篇 |
出版年
2023年 | 377篇 |
2022年 | 523篇 |
2021年 | 1404篇 |
2020年 | 847篇 |
2019年 | 1381篇 |
2018年 | 1668篇 |
2017年 | 1243篇 |
2016年 | 1364篇 |
2015年 | 1596篇 |
2014年 | 2376篇 |
2013年 | 3227篇 |
2012年 | 5257篇 |
2011年 | 5383篇 |
2010年 | 3007篇 |
2009年 | 2675篇 |
2008年 | 4885篇 |
2007年 | 5341篇 |
2006年 | 5246篇 |
2005年 | 4976篇 |
2004年 | 4774篇 |
2003年 | 4317篇 |
2002年 | 4211篇 |
2001年 | 581篇 |
2000年 | 407篇 |
1999年 | 636篇 |
1998年 | 901篇 |
1997年 | 755篇 |
1996年 | 635篇 |
1995年 | 606篇 |
1994年 | 491篇 |
1993年 | 465篇 |
1992年 | 348篇 |
1991年 | 304篇 |
1990年 | 259篇 |
1989年 | 246篇 |
1988年 | 261篇 |
1987年 | 213篇 |
1986年 | 231篇 |
1985年 | 240篇 |
1984年 | 308篇 |
1983年 | 324篇 |
1982年 | 385篇 |
1981年 | 369篇 |
1980年 | 344篇 |
1979年 | 197篇 |
1978年 | 239篇 |
1977年 | 191篇 |
1976年 | 133篇 |
1975年 | 102篇 |
1974年 | 105篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
902.
903.
904.
Alia Al-Tayyib Stephen Koester Sig Langegger Lisa Raville 《Substance use & misuse》2017,52(8):1051-1058
Objective: We sought to describe an emerging drug use pattern characterized by injection of both methamphetamine and heroin. We examined differences in drug injection patterns by demographics, injection behaviors, HIV and HCV status, and overdose. Methods: Persons who inject drugs (PWID) were recruited as part of the National HIV Behavioral Surveillance (NHBS) system in Denver, Colorado. We used chi-square statistics to assess differences between those who reported only heroin injection, only methamphetamine injection, and combined heroin and methamphetamine injection. We used generalized linear models to estimate unadjusted and adjusted prevalence ratios to describe the association between drug injection pattern and reported nonfatal overdose in 2015. We also examined changes in the drug reported as most frequently injected across previous NHBS cycles from 2005, 2009, and 2012. Results: Of 592 participants who completed the survey in 2015, 173 (29.2%) reported only injecting heroin, 123 (20.8%) reported only injecting methamphetamine, and 296 (50.0%) reported injecting both drugs during the past 12 months. Injecting both heroin and methamphetamine was associated with a 2.8 (95% confidence interval: 1.7, 4.5) fold increase in reported overdose in the past 12 months compared with only injecting heroin. The proportion of those reporting methamphetamine as the most frequently injected drug increased from 2.1% in 2005 to 29.6% in 2015 (p < 0.001). Conclusions: The rapid increase in methamphetamine injection, and the emergence of combining methamphetamine with heroin, may have serious public health implications. 相似文献
905.
906.
907.
908.
Paul M. Young Stephen Edge John N. Staniforth D. Fraser Steele Robert Price 《Pharmaceutical development and technology》2013,18(2):211-216
The relationship between the apparent moisture content and moisture sorption of modified starches was investigated. Samples of sodium starch glycolate (SSG), pregelatinized starch (PGS) and potato starch (PS) were stored for various times at 44% or 75% relative humidity (RH) to produce samples with moisture contents of up to 14%, as determined by loss on drying (LOD). Evaluation of LOD and mass gain data suggested that measured mass gain equated to predicted LOD values for PGS and PS. However, in SSG there was a nonstoichiometric relationship between mass gain and predicted LOD. In addition, samples of SSG displayed hysteresis during dynamic vapor sorption (DVS) cycling in that an apparent mass loss of about 2–3% was observed for two of the SSGs, with PS and PGS exhibiting reversibility. In some cases, SSG exhibited an apparent mass loss during the DVS cycle at with 50% RH. These observations suggest that one or more of the components of SSG “interact” with moisture. Because X-ray diffraction suggested there was no dramatic change in the crystallinity of SSG, an exchange of residual SSG solvent, alcohol, with moisture may, in part, explain the moisture sorption behavior of SSG. 相似文献
909.
910.
Stephen W. Carmichael 《Clinical anatomy (New York, N.Y.)》2014,27(2):162-168
Langer's lines are often considered to be guides for elective surgical incisions. Interestingly, Karl Langer was not the first to describe the property of skin that leads to the lines he depicted, nor are these lines in common use today. Rather, it is common that relaxed skin tension lines provide a guide for cosmetically pleasing surgical results. Nevertheless, Langer did conduct extensive studies on human skin that remain as a scholarly body of work. Clin. Anat. 27:162–168, 2014. © 2013 Wiley Periodicals, Inc. 相似文献