全文获取类型
收费全文 | 121979篇 |
免费 | 12214篇 |
国内免费 | 3221篇 |
专业分类
耳鼻咽喉 | 1089篇 |
儿科学 | 3081篇 |
妇产科学 | 1416篇 |
基础医学 | 10960篇 |
口腔科学 | 3700篇 |
临床医学 | 16661篇 |
内科学 | 16981篇 |
皮肤病学 | 1671篇 |
神经病学 | 5089篇 |
特种医学 | 3988篇 |
外国民族医学 | 9篇 |
外科学 | 17996篇 |
综合类 | 16589篇 |
现状与发展 | 5篇 |
一般理论 | 4篇 |
预防医学 | 13551篇 |
眼科学 | 1307篇 |
药学 | 9725篇 |
251篇 | |
中国医学 | 7958篇 |
肿瘤学 | 5383篇 |
出版年
2024年 | 507篇 |
2023年 | 2495篇 |
2022年 | 3810篇 |
2021年 | 5665篇 |
2020年 | 5611篇 |
2019年 | 4832篇 |
2018年 | 4720篇 |
2017年 | 4996篇 |
2016年 | 5227篇 |
2015年 | 5048篇 |
2014年 | 8907篇 |
2013年 | 9293篇 |
2012年 | 7963篇 |
2011年 | 8257篇 |
2010年 | 6391篇 |
2009年 | 6385篇 |
2008年 | 6254篇 |
2007年 | 5918篇 |
2006年 | 5369篇 |
2005年 | 4731篇 |
2004年 | 3817篇 |
2003年 | 3156篇 |
2002年 | 2497篇 |
2001年 | 2158篇 |
2000年 | 1876篇 |
1999年 | 1531篇 |
1998年 | 1257篇 |
1997年 | 1155篇 |
1996年 | 975篇 |
1995年 | 875篇 |
1994年 | 741篇 |
1993年 | 658篇 |
1992年 | 603篇 |
1991年 | 449篇 |
1990年 | 385篇 |
1989年 | 333篇 |
1988年 | 306篇 |
1987年 | 279篇 |
1986年 | 255篇 |
1985年 | 270篇 |
1984年 | 219篇 |
1983年 | 124篇 |
1982年 | 182篇 |
1981年 | 152篇 |
1980年 | 129篇 |
1979年 | 137篇 |
1978年 | 106篇 |
1977年 | 95篇 |
1976年 | 72篇 |
1973年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
1.
《Journal of the Academy of Nutrition and Dietetics》2022,122(11):2060-2071
BackgroundVoices for Food was a longitudinal community, food pantry–based intervention informed by the social ecological model, and designed to improve food security, dietary intake, and quality among clients, which was carried out in 24 rural food pantries across 6 Midwestern states.ObjectiveOur objective was to evaluate changes in adult food security, dietary intake, and quality from baseline (2014) to follow-up (2016), and to assess the role of adult food security on dietary outcomes.DesignA multistate, longitudinal, quasi-experimental intervention with matched treatment and comparison design was used to evaluate treatment vs comparison group changes over time and changes in both groups over time.Participants/settingAdult food pantry clients (n = 617) completed a demographic food security survey, and up to three 24-hour dietary recalls at baseline (n = 590) and follow-up (n = 160).InterventionCommunity coaching served as the experimental component, which only “treatment” communities received, and a food council guide and food pantry toolkit were provided to both “treatment” and matched “comparison” communities.Main outcome measuresChange in adult food security status, mean usual intakes of nutrients and food groups, and Healthy Eating Index-2010 scores were the main outcome measures.Statistical analyses performedLinear mixed models estimated changes in outcomes by intervention group and by adult food security status over time.ResultsImprovements in adult food security score (–0.7 ± 0.3; P = .01), Healthy Eating Index-2010 total score (4.2 ± 1.1; P < .0001), and empty calories component score (3.4 ± 0.5; P <.0001) from baseline to follow-up were observed in treatment and comparison groups, but no statistically significant changes were found for adult food security status, dietary quality, and usual intakes of nutrients and food groups between the 2 groups over time. The intervention effect on dietary quality and usual intake changes over time by adult food security status were also not observed.ConclusionsFood pantry clients in treatment and comparison groups had higher food security and dietary quality at the follow-up evaluation of the Voices for Food intervention trial compared with baseline, despite the lack of difference among the groups as a result of the experimental coaching component. 相似文献
2.
Forensic pathologists often encounter autopsies that require an assessment of antemortem general conditions (e.g., infection, metabolic disorders). To establish evaluation clues for such cases, we quantitatively examined macrophages and the general pathology of bone marrow in samples from 180 forensic autopsy cases of decedents with various conditions. Hematoxylin-eosin staining, Berlin blue staining, and immunostainings for CD163, CD138, and CD61 were performed. We determined the numbers per field (density) of total macrophages, swollen macrophages, macrophages with hemophagocytosis, and hemosiderin-laden macrophages. Each density was standardized by identifying its ratio to the total number of macrophages. The decedents' background data (cause of death, other pathological findings, postmortem interval, antemortem symptoms, and presence of resuscitation) were extracted. No correlations were found between the postmortem interval and the other decedent data, indicating that these data are not affected by postmortem changes. In the group in which inflammatory disease was the cause of death, there were significant elevations in the ratio of the swollen macrophage density to total macrophages. Significantly higher ratios of the density of swollen and hemophagocytic macrophages were observed in the group in which conditions with a prolonged agonal period were the cause of death. The group with a return of spontaneous circulation to resuscitation showed a significantly higher ratio of macrophage density with hemophagocytosis. This study provides the first statistical analysis focused on bone marrow histopathology in forensic autopsies. The results will be useful for elucidating causes of death and agonal-period conditions. 相似文献
3.
背景 致密性骨炎(OCI)和其他疾病有时难以鉴别,探讨血清骨转换生化标志物可为OCI的鉴别诊断提供依据。 目的 探索女性OCI患者的血清骨转换生化标志物的水平变化及临床意义。 方法 回顾性选取2013年6月至2022年2月在北京积水潭医院门诊及住院诊断为OCI的61例女性患者作为观察组,年龄15~50岁,平均(33.8±6.6)岁,病程2周~15年。选择同期61例女性体检健康者作为对照组,年龄15~48岁,平均(35.6±7.6)岁。比较两组一般临床资料和血清骨转换生化标志物水平,并对血清骨转换生化标志物与病情相关指标进行相关性分析。 结果 观察组血清白蛋白(45.4±2.9)g/L低于对照组(46.5±2.8)g/L(t=2.190,P<0.05)。血清骨转换生化标志物比较结果显示,观察组血清1型胶原羧基末端肽β特殊序列(β-CTX)〔0.28(0.23,0.37)μg/L〕、N-端骨钙素(OC)〔13.1(11.2,16.2)μg/L〕、25-羟维生素D3〔25-(OH)VD3〕〔(14.1±5.1)μg/L〕低于对照组〔0.36(0.29,0.48)μg/L,15.6(13.7,17.3)μg/L,(17.5±6.6)μg/L〕(Z=-2.983、-3.255,t=3.081,P<0.05)。长病程亚组OC水平〔14.6(12.4,18.5)μg/L〕高于短病程亚组〔11.7(10.2,14.0)μg/L〕(Z=-2.407,P<0.05)。多孕亚组β-CTX〔0.25(0.22,0.32)μg/L〕、OC水平〔12.2(10.3,15.0)μg/L〕低于非多孕亚组〔0.33(0.26,0.44)μg/L、13.4(12.0,18.8)μg/L〕(Z=-2.486、-1.897,P<0.05)。相关性分析显示,观察组血清1型前胶原氨基端延长肽(tP1NP)与妊娠次数、生产次数均呈负相关(rs=-0.276、-0.298,P<0.05),OC与体质指数(BMI)、视觉模拟评分法(VAS)评分、妊娠次数均呈负相关(rs=-0.284、-0.374、-0.360,P<0.05),25-(OH)VD3水平与BMI呈正相关(rs=0.275,P<0.05)。 结论 女性OCI患者血清OC、β-CTX水平明显降低,可为鉴别其他疾病提供依据;血清OC水平可以反映OCI患者的严重程度,同时OC水平与患者妊娠次数相关;tP1NP与妊娠次数、生产次数相关。 相似文献
4.
5.
6.
7.
8.
9.
10.
Qian Zhang Larry D. Mesner Gina M. Calabrese Naomi Dirckx Zhu Li Angela Verardo Qian Yang Robert J. Tower Marie-Claude Faugere Charles R. Farber Thomas L. Clemens 《The Journal of clinical investigation》2021,131(7)
Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture. GWAS have identified hundreds of loci influencing BMD, but few have been functionally analyzed. In this study, we show that SNPs within a BMD locus on chromosome 14q32.32 alter splicing and expression of PAR-1a/microtubule affinity regulating kinase 3 (MARK3), a conserved serine/threonine kinase known to regulate bioenergetics, cell division, and polarity. Mice lacking Mark3 either globally or selectively in osteoblasts have increased bone mass at maturity. RNA profiling from Mark3-deficient osteoblasts suggested changes in the expression of components of the Notch signaling pathway. Mark3-deficient osteoblasts exhibited greater matrix mineralization compared with controls that was accompanied by reduced Jag1/Hes1 expression and diminished downstream JNK signaling. Overexpression of Jag1 in Mark3-deficient osteoblasts both in vitro and in vivo normalized mineralization capacity and bone mass, respectively. Together, these findings reveal a mechanism whereby genetically regulated alterations in Mark3 expression perturb cell signaling in osteoblasts to influence bone mass. 相似文献