全文获取类型
收费全文 | 502093篇 |
免费 | 35320篇 |
国内免费 | 10676篇 |
专业分类
耳鼻咽喉 | 6189篇 |
儿科学 | 9803篇 |
妇产科学 | 12422篇 |
基础医学 | 67584篇 |
口腔科学 | 13795篇 |
临床医学 | 46231篇 |
内科学 | 98461篇 |
皮肤病学 | 9910篇 |
神经病学 | 34028篇 |
特种医学 | 18106篇 |
外国民族医学 | 152篇 |
外科学 | 73447篇 |
综合类 | 28265篇 |
现状与发展 | 25篇 |
一般理论 | 73篇 |
预防医学 | 25290篇 |
眼科学 | 13051篇 |
药学 | 43470篇 |
116篇 | |
中国医学 | 8131篇 |
肿瘤学 | 39540篇 |
出版年
2022年 | 5862篇 |
2021年 | 8541篇 |
2020年 | 5890篇 |
2019年 | 6797篇 |
2018年 | 8613篇 |
2017年 | 7083篇 |
2016年 | 6952篇 |
2015年 | 9194篇 |
2014年 | 12155篇 |
2013年 | 13479篇 |
2012年 | 18953篇 |
2011年 | 19986篇 |
2010年 | 12122篇 |
2009年 | 10532篇 |
2008年 | 15977篇 |
2007年 | 16796篇 |
2006年 | 16743篇 |
2005年 | 15811篇 |
2004年 | 13286篇 |
2003年 | 12772篇 |
2002年 | 11801篇 |
2001年 | 30780篇 |
2000年 | 31481篇 |
1999年 | 26651篇 |
1998年 | 7268篇 |
1997年 | 6328篇 |
1996年 | 5373篇 |
1995年 | 4914篇 |
1994年 | 4367篇 |
1993年 | 3656篇 |
1992年 | 17080篇 |
1991年 | 15702篇 |
1990年 | 14943篇 |
1989年 | 14638篇 |
1988年 | 13162篇 |
1987年 | 12580篇 |
1986年 | 11496篇 |
1985年 | 10670篇 |
1984年 | 7118篇 |
1983年 | 5749篇 |
1982年 | 2832篇 |
1979年 | 5593篇 |
1978年 | 3412篇 |
1977年 | 3017篇 |
1975年 | 2697篇 |
1974年 | 3124篇 |
1973年 | 2907篇 |
1972年 | 2847篇 |
1971年 | 2802篇 |
1969年 | 2570篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Yi Li Ying Chen Xiang Li Jian Wu Jing-Ying Pan Ri-Xin Cai Ri-Yun Yang Xiao-Dong Wang 《中国神经再生研究》2019,(9)
In the search for a therapeutic schedule for spinal cord injury, it is necessary to understand key genes and their corresponding regulatory networks involved in the spinal cord injury process. However, ad hoc selection and analysis of one or two genes cannot fully reveal the complex molecular biological mechanisms of spinal cord injury. The emergence of second-generation sequencing technology(RNA sequencing) has provided a better method. In this study, RNA sequencing technology was used to analyze differentially expressed genes at different time points after spinal cord injury in rat models established by contusion of the eighth thoracic segment. The numbers of genes that changed significantly were 944, 1362 and 1421 at 1, 4 and 7 days after spinal cord injury respectively. After gene ontology analysis and temporal expression analysis of the differentially expressed genes, C5ar1, Socs3 and CCL6 genes were then selected and identified by real-time polymerase chain reaction and western blot assay. The mRNA expression trends of C5ar1, Socs3 and CCL6 genes were consistent with the RNA sequencing results. Further verification and analysis of C5ar1 indicate that the level of protein expression of C5ar1 was consistent with its nucleic acid level after spinal cord injury. C5ar1 was mainly expressed in neurons and astrocytes. Finally, the gene Itgb2,which may be related to C5ar1, was found by Chilibot database and literature search. Immunofluorescence histochemical results showed that the expression of Itgb2 was highly consistent with that of C5ar1. Itgb2 was expressed in astrocytes. RNA sequencing technology can screen differentially expressed genes at different time points after spinal cord injury. Through analysis and verification, genes strongly associated with spinal cord injury can be screened. This can provide experimental data for further determining the molecular mechanism of spinal cord injury, and also provide possible targets for the treatment of spinal cord injury. This study was approved ethically by the Laboratory Animal Ethics Committee of Jiangsu Province, China(approval No. 2018-0306-001) on March 6, 2018. 相似文献
62.
63.
Y. Ermias I.A. Morgan K.M. Curtis M.K. Whiteman L.G. Horton L.B. Zapata 《Contraception》2019,99(5):300-305
ObjectiveIdentify factors associated with healthcare providers' frequency of depot medroxyprogesterone acetate (DMPA) provision to adolescents.Study designWe analyzed data from surveys mailed to a nationally representative sample of public-sector providers and office-based physicians (n=1984). We estimated adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of factors associated with frequent DMPA provision to adolescents in the past year.ResultsAlthough most providers (>95%) considered DMPA safe for adolescents, fewer reported frequent provision (89% of public-sector providers; 64% of office-based physicians). Among public-sector providers, factors associated with lower odds of frequent provision included working in settings without Title X funding (aOR 0.44, 95% CI 0.30–0.64), reporting primary care as their primary clinical focus versus reproductive or adolescent health (aOR 0.42, 95% CI 0.28–0.61), and providing fewer patients with family planning services. Among office-based physicians, factors associated with lower odds of frequent provision included specializing in obstetrics/gynecology (aOR 0.50, 95% CI 0.27–0.91) and family medicine (aOR 0.21, 95% CI 0.09–0.47) versus adolescent medicine, completing training ≥15 versus <5 years ago (aOR 0.27, 95% CI 0.09–0.83), and reporting that 0–24% of patients pay with Medicaid or other government healthcare assistance versus ≥50% (aOR 0.23, 95% CI 0.09–0.61). The reason most commonly reported by providers for infrequent DMPA provision was patient preference for another method.ConclusionsWhile most providers reported frequently providing DMPA to adolescents, training on evidence-based recommendations for contraception, focused on subgroups of providers with lower odds of frequent DMPA provision, may increase adolescents' access to contraception.ImplicationsAlthough >95% of providers considered depot medroxyprogesterone (DMPA) a safe contraceptive for adolescents, only 89% of public-sector providers and 64% of office-based physicians reported frequently providing DMPA to adolescents. Provider training on evidence-based recommendations for contraception counseling and provision may increase adolescents' access to DMPA and all methods of contraception. 相似文献
64.
65.
Prevention Science - This study aimed to evaluate the effectiveness of the drug and violence resistance educational program (PROERD) on short-term secondary outcomes, such as intentions to use... 相似文献
66.
Xiaojie Wu Leyan Zhang Jiadi Zhou Luying Liu Qiang Fu Aili Fu Xiaoying Feng Rui Xin Hongrui Liu Yong Gao Jiangnan Xue 《Current problems in cancer》2019,43(1):18-26
Aim
Leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) is an immune inhibitory receptor which is expressed within most types of hematopoietic cells and negatively regulates immune responses. Recently, we found LAIR-1 expression to be present within tumors of nonhematopoietic lineages. However, the roles of LAIR-1 in hepatocellular carcinoma (HCC) have yet to be examined. The purpose of this study was to investigate the expression of LAIR-1 in HCC tissue and assess its clinical significance at this site.Materials and methods
Expression levels of LAIR-1 within HCC samples collected from 90 patients and compared with that of slides of normal liver tissue collected from 9 non-HCC patients were measured by immunohistochemistry using tissue microarrays. A semiquantitative score was assigned, as was based on staining intensity and percent of positive cells and a Spearman Rank correlation test was used to assess any potential significant correlations between LAIR-1 expression and clinicopathological factors. Overall survival analysis was performed using the Kaplan-Meier and Log Rank statistical test.Results
LAIR-1 expression was detected in cancer tissue and adjacent tumor tissue, but not in normal liver tissue. The percent of LAIR-1-positive expression in cancer tissue of HCC samples was 97.78% (88/90) while that in adjacent tumor tissue was 96.67% (87/90). Significantly greater expression levels of LAIR-1 were obtained from cancer tissue (Mean?±?SD?=?5.722?±?2.145) than that in adjacent tumor tissue (4.141?±?1.486). In addition, LAIR-1 expression was found to be significantly correlated with pathological grade of HCC, T stage, and age. Expression levels of LAIR-1 were related with worse overall survival rates of HCC patients, especially in HCC patients with hepatic cirrhosis.Conclusion
Results of this study show that LAIR-1 is expressed in HCC tissues and that high levels of LAIR-1 expression are associated with the poor cancer differentiation. In addition, overexpression of LAIR-1 was significantly associated with worse overall survival in the patients with HCC. These data suggest that LAIR-1 may be an independent predictor for clinical outcomes in patients with HCC. 相似文献67.
68.
69.
70.
Jin Wu Hao Wang Qing Li Qian-Ying Guo Si-Qi Tao Yu-Xian Shen Zheng-Sheng Wu 《Pathology, research and practice》2019,215(9):152523
Mammary carcinoma (MC) is one of most common malignancy in women, and ring finger protein 2 (RNF2) possesses various roles in vast human tumors. In MC tissues as well as in cell lines RNF2 exhibited high expression, had significant association with tumor size, lymph node status, TNM stage, patients’ poor survival, and promoted cell proliferation, colony formation, cell migration and invasion of MC cell lines which was mediated by downregulation of E-cadherin protein. These data reveal that RNF2 protein plays a vital role in the development of MC and may be a potential therapy target of MC. 相似文献