首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   5170篇
  免费   286篇
  国内免费   23篇
耳鼻咽喉   91篇
儿科学   273篇
妇产科学   36篇
基础医学   553篇
口腔科学   119篇
临床医学   348篇
内科学   1170篇
皮肤病学   189篇
神经病学   272篇
特种医学   91篇
外科学   883篇
综合类   123篇
一般理论   1篇
预防医学   222篇
眼科学   185篇
药学   414篇
中国医学   16篇
肿瘤学   493篇
  2024年   2篇
  2023年   28篇
  2022年   29篇
  2021年   176篇
  2020年   103篇
  2019年   142篇
  2018年   188篇
  2017年   123篇
  2016年   160篇
  2015年   177篇
  2014年   256篇
  2013年   312篇
  2012年   495篇
  2011年   504篇
  2010年   288篇
  2009年   225篇
  2008年   359篇
  2007年   336篇
  2006年   326篇
  2005年   295篇
  2004年   260篇
  2003年   245篇
  2002年   206篇
  2001年   26篇
  2000年   24篇
  1999年   28篇
  1998年   29篇
  1997年   21篇
  1996年   22篇
  1995年   12篇
  1994年   9篇
  1993年   12篇
  1992年   6篇
  1991年   5篇
  1990年   6篇
  1989年   10篇
  1988年   7篇
  1987年   3篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1982年   3篇
  1981年   3篇
  1980年   1篇
  1978年   1篇
  1977年   1篇
  1976年   2篇
  1970年   1篇
  1954年   1篇
  1949年   1篇
排序方式: 共有5479条查询结果,搜索用时 15 毫秒
1.
2.
3.

Background

Major depressive disorder (MDD) is a multifactorial disease which often coexists with cognitive deficits. Depression-induced cognitive deficits are known to be associated with aberrant reward processing, neurochemical and structural alterations. Recent studies have shown that chronic electrical stimulation of brain reward areas induces a robust antidepressant effect. However, the effects of repeated electrical self-stimulation of lateral hypothalamus - medial forebrain bundle (LH-MFB) on depression-induced cognitive deficits and associated neurochemical and structural alterations in the prefrontal cortex (PFC) are unknown.

Objectives

We investigated the effect of chronic rewarding self-stimulation of LH-MFB in neonatal clomipramine (CLI) model of depression. During adulthood, neonatal CLI and saline administered rats were implanted with bilateral electrodes stereotaxically in the LH-MFB and trained to receive intracranial self-stimulation (ICSS) for 14 days. The rats were tested for depressive-like behaviors, learning and memory followed by estimation of PFC volumes, levels of monoamines and its metabolites in the PFC.

Results

We found that chronic ICSS of LH-MFB reverses CLI-induced behavioral despair and anhedonia. Interestingly, self-stimulation normalizes the impaired novel object and location recognition memory in CLI rats. The amelioration of learning impairments in CLI rats was associated with the reversal of volume loss and restoration of monoamine metabolism in the PFC.

Conclusion

We demonstrated that repeated intracranial self-stimulation of LH-MFB ameliorates CLI-induced learning deficits, reverses altered monoamine metabolism and the atrophy of PFC. Our results support the hypothesis that chronic brain stimulation rewarding experience might be evolved as a potential treatment strategy for reversal of learning deficits in depression and associated disorders.  相似文献   
4.
5.

Background

Stereotactic body radiation therapy (SBRT) is standard for medically inoperable stage I non–small-cell lung cancer (NSCLC) and is emerging as a surgical alternative in operable patients. However, limited long-term outcomes data exist, particularly according to operability. We hypothesized long-term local control (LC) and cancer-specific survival (CSS) would not differ by fractionation schedule, tumor size or location, or operability status, but overall survival (OS) would be higher for operable patients.

Patients and Methods

All consecutive patients with stage I (cT1-2aN0M0) NSCLC treated with SBRT from June 2009 to July 2013 were assessed. Thoracic surgeon evaluation determined operability. Local failure was defined as growth following initial tumor shrinkage or progression on consecutive scans. LC, CSS, and OS were calculated using Cox proportional hazards regression.

Results

A total of 186 patients (204 lesions) were analyzed. Most patients were inoperable (82%) with Eastern Cooperative Oncology Group performance status of 1 (59%) or 2 (26%). All lesions received biological effective doses ≥ 100 Gy most commonly (94%) in 3 to 5 fractions. The median follow-up was 4.0 years. LC at 2 and 5 years were 95.6% (95% confidence interval, 92%-99%) and 93.7% (95% confidence interval, 90%-98%), respectively. Compared with operable patients, inoperable patients did not have significant differences in 5-year LC (93.1% vs. 96.7%; P = .49), nodal failure (31.4% vs. 11.0%; P = .12), distant failure (12.2% vs. 10.4%; P = .98), or CSS (80.6% vs. 91.0%; P = .45) but trended towards worse OS (34.2% vs. 45.3%; P = .068). Tumor size, location, and fractionation did not significantly influence outcomes.

Conclusions

SBRT has excellent, durable LC and CSS rates for early-stage NSCLC, although inoperable patients had somewhat lower OS than operable patients, likely owing to greater comorbidities.  相似文献   
6.
There is an unmet need to overcome nongenetic therapy-resistance to improve outcomes in AML, especially post-myeloproliferative neoplasm (MPN) secondary (s) AML. Studies presented describe effects of genetic knockout, degradation or small molecule targeted-inhibition of GFI1/LSD1 on active enhancers, altering gene-expressions and inducing differentiation and lethality in AML and (MPN) sAML cells. A protein domain-focused CRISPR screen in LSD1 (KDM1A) inhibitor (i) treated AML cells, identified BRD4, MOZ, HDAC3 and DOT1L among the codependencies. Our findings demonstrate that co-targeting LSD1 and one of these co-dependencies exerted synergistic in vitro lethality in AML and post-MPN sAML cells. Co-treatment with LSD1i and the JAKi ruxolitinib was also synergistically lethal against post-MPN sAML cells. LSD1i pre-treatment induced GFI1, PU.1 and CEBPα but depleted c-Myc, overcoming nongenetic resistance to ruxolitinib, or to BETi in post-MPN sAML cells. Co-treatment with LSD1i and BETi or ruxolitinib exerted superior in vivo efficacy against post-MPN sAML cells. These findings highlight LSD1i-based combinations that merit testing for clinical efficacy, especially to overcome nongenetic therapy-resistance in AML and post-MPN sAML.Subject terms: Acute myeloid leukaemia, Targeted therapies  相似文献   
7.
Brain metastases are a major cause of melanoma-related mortality and morbidity. We undertook whole-exome sequencing of 50 tumours from patients undergoing surgical resection of brain metastases presenting as the first site of visceral disease spread and validated our findings in an independent dataset of 18 patients. Brain metastases had a similar driver mutational landscape to cutaneous melanomas in TCGA. However, KRAS was the most significantly enriched driver gene, with 4/50 (8%) of brain metastases harbouring non-synonymous mutations. Hotspot KRAS mutations were mutually exclusive from BRAFV600, NRAS and HRAS mutations and were associated with a reduced overall survival from the resection of brain metastases (HR 10.01, p = 0.001). Mutations in KRAS were clonal and concordant with extracranial disease, suggesting that these mutations are likely present within the primary. Our analyses suggest that KRAS mutations could help identify patients with primary melanoma at higher risk of brain metastases who may benefit from more intensive, protracted surveillance.Subject terms: CNS cancer, Metastasis, Melanoma, Tumour biomarkers, Cancer  相似文献   
8.
International Journal of Diabetes in Developing Countries -  相似文献   
9.
10.
Hepatic NADPH-cytochrome P450 oxidoreductase null (HRN?) mice exhibit normal hepatic and extrahepatic biotransformation enzyme activities when compared to wild-type (WT) mice, but express no functional hepatic cytochrome P450 activities. When incubated in vitro with [14C]-diclofenac, liver microsomes from WT mice exhibited extensive biotransformation to oxidative and glucuronide metabolites and covalent binding to proteins was also observed. In contrast, whereas glucuronide conjugates and a quinone-imine metabolite were formed when [14C]-diclofenac was incubated with HRN? mouse liver, only small quantities of P450-derived oxidative metabolites were produced in these samples and covalent binding to proteins was not observed. Livers from vehicle-treated HRN? mice exhibited enhanced lipid accumulation, bile duct proliferation, hepatocellular degeneration and necrosis and inflammatory cell infiltration, which were not present in livers from WT mice. Elevated liver-derived alanine aminotransferase, glutamate dehydrogenase and alkaline phosphatase activities were also observed in plasma from HRN? mice. When treated orally with diclofenac for 7 days, at 30 mg/kg/day, the severities of the abnormal liver histopathology and plasma liver enzyme findings in HRN? mice were reduced markedly. Oral diclofenac administration did not alter the liver histopathology or elevate plasma enzyme activities of WT mice. These findings indicate that HRN? mice are valuable for exploration of the role played by hepatic P450s in drug biotransformation, but poorly suited to investigations of drug-induced liver toxicity. Nevertheless, studies in HRN? mice could provide novel insights into the role played by inflammation in liver injury and may aid the evaluation of new strategies for its treatment.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号