全文获取类型
收费全文 | 2265篇 |
免费 | 278篇 |
国内免费 | 100篇 |
出版年
2023年 | 19篇 |
2022年 | 29篇 |
2021年 | 90篇 |
2020年 | 83篇 |
2019年 | 103篇 |
2018年 | 90篇 |
2017年 | 78篇 |
2016年 | 106篇 |
2015年 | 131篇 |
2014年 | 171篇 |
2013年 | 178篇 |
2012年 | 198篇 |
2011年 | 150篇 |
2010年 | 109篇 |
2009年 | 116篇 |
2008年 | 116篇 |
2007年 | 113篇 |
2006年 | 87篇 |
2005年 | 69篇 |
2004年 | 84篇 |
2003年 | 86篇 |
2002年 | 76篇 |
2001年 | 62篇 |
2000年 | 33篇 |
1999年 | 34篇 |
1998年 | 20篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 14篇 |
1994年 | 32篇 |
1993年 | 13篇 |
1992年 | 32篇 |
1991年 | 20篇 |
1990年 | 12篇 |
1989年 | 13篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有2643条查询结果,搜索用时 31 毫秒
1.
2.
Zhe-Xuan Li Yu-Mei Wang Fu-Bing Tang Lian Zhang Yang Zhang Jun-Ling Ma Tong Zhou Wei-Cheng You Kai-Feng Pan 《PloS one》2015,10(5)
BackgroundGenetic variants of nucleotide-binding oligomerization domain-containing protein (NOD) may influence the outcome of Helicobacter pylori (H. pylori) infection and gastric carcinogenesis. To explore genetic variants of NOD1 and NOD2 in association with gastric cancer (GC) and its precursors, a population-based study was conducted in Linqu County, China.MethodsTagSNPs of NOD1 and NOD2 were genotyped by Sequenom MASS array in 132 GCs, and 1,198 subjects with precancerous gastric lesions, and were correlated with evolution of gastric lesions in 766 subjects with follow-up data.ResultsAmong seven tagSNPs, NOD1 rs2709800 and NOD2 rs718226 were associated with gastric lesions. NOD1 rs2709800 TG genotype carriers had a decreased risk of intestinal metaplasia (IM, OR: 0.53; 95% CI: 0.31–0.92), while NOD2 rs718226 G allele (AG/GG) showed increased risks of dysplasia (DYS, OR: 2.96; 95% CI: 1.86–4.71) and GC (OR: 2.35; 95% CI: 1.24–4.46). Moreover, an additive interaction between rs718226 and H. pylori was found in DYS or GC with synergy index of 3.08 (95% CI: 1.38–6.87) or 3.99 (95% CI: 1.55–10.22), respectively. The follow-up data indicated that NOD2 rs2111235 C allele (OR: 0.52; 95% CI: 0.32–0.83) and rs7205423 G allele (OR: 0.56; 95% CI: 0.35–0.89) were associated with decreased risk of progression in H. pylori-infected subjects.ConclusionsNOD1 rs2709800, NOD2 rs718226, rs2111235, rs7205423 and interaction between rs718226 and H. pylori infection may be related to risk of gastric lesions. 相似文献
3.
4.
5.
Background
Circulating microRNAs (miRNAs) are emerging as promising biomarkers for human cancer. Osteosarcoma is the most common human primary malignant bone tumor in children and young adults. The objective of this study was to investigate whether circulating miRNAs in plasma could be a useful biomarker for detecting osteosarcoma and monitoring tumor removal dynamics.Methods
Plasma samples were obtained from 90 patients before surgery, 50 patients after one month of surgery, and 90 healthy individuals. The study was divided into three steps: First, initial screening of the profiles of circulating miRNAs in pooled plasma samples from healthy controls and pre-operative osteosarcoma patients using a TaqMan low density array (TLDA). Second, evaluation of miRNA concentration in individual plasma samples from 90 pre-operative osteosarcoma patients and 90 healthy controls by a quantitative real time PCR (qRT-PCR) assay. Third, evaluation of miRNA concentration in paired plasma samples from 50 pre- and post-operative osteosarcoma patients by qRT-PCR assay.Results
Four plasma miRNAs including miR-195-5p, miR-199a-3p, miR-320a, and miR-374a-5p were significantly increased in the osteosarcoma patients. Receiver operating characteristics curve analysis of the combined populations demonstrated that the four-miRNA signature could discriminate cases from controls with an area under the curve of 0.9608 (95% CI 0.9307-0.9912). These 4 miRNAs were markedly decreased in the plasma after operation. In addition, circulating miR-195-5p and miR-199a-3p were correlated with metastasis status, while miR-199a-3p and miR-320a were correlated with histological subtype.Conclusions
Our data suggest that altered levels of circulating miRNAs might have great potential to serve as novel, non-invasive biomarkers for osteosarcoma. 相似文献6.
Introduction: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) which are used for assessment of axial spondyloarthritis (AxSpA) related disease activity have poor specificity and sensitivity. Neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) and mean platelet volume (MPV) have not been investigated as disease activity markers among Asian AxSpA patients.Methodology: A retrospective, cross-sectional study was conducted in Singapore General Hospital from January 2013 to December 2015 to investigate the role of NLR, PLR and MPV as disease activity markers in AxSpA patients.Results: The mean age of patients (n?=?122) was 37.0?±?12.5 years old and majority of them were male (n?=?93, 76.2%). No significant differences were found between patients with disease with regards to age, gender, ethnicity, HLAB-27 status, age at onset of diagnosis of AxSpA, duration of disease and comorbidities such as cardiac disease (p?>?0.05).There were no significant differences in the ESR, NLR, PLR and MPV between the four disease activity groups (p?>?0.05). However, patients with very high disease activity had higher ESR and CRP compared to patients with inactive disease and moderate disease activity (p?0.05).Conclusion: NLR, PLR and MPV were not associated with disease activity in Asian AxSpA patients. 相似文献
7.
8.
Yi-Ru Wang Kun-Lin Chen Cheng-Min Li Lian Li Gen-Lin Wang 《Journal of cellular physiology》2019,234(4):3961-3972
Heat stress can inhibit follicular development in dairy cows, and thus can affect their reproductive performance. Follicular granulosa cells can synthesize estrogen, that affects the development and differentiation of follicles by apoptosis. Heme oxygenase 1 (HO-1/heat shock protein 32) plays an antiapoptotic and cytoprotective role in various cells during stress-induced apoptosis, but little is known about its definitive function in bovine (ovarian) granulosa cells (bGCs). In our study, the roles and mechanism of HO-1 on the heat stress-induced apoptosis of bGCs were studied. Our results show that the expression of HO-1 was significantly increased under heat stress. Moreover, HO-1 silencing increased apoptosis, whereas its overexpression dampened apoptosis by regulating the expression of Bax/Bcl-2 and the levels of cleaved caspase-3. In addition, HO-1 can also play a cytoprotective role by affecting estrogen levels and decomposing heme to produce biologically active metabolite carbon monoxide (CO). Meanwhile, CO significantly increased the level of HO-1, decreased Bax/Bcl-2 levels, and inhibited the activation of extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. The apoptosis of ovarian GCs can affect the secretion of estrogen and lead to disorder of the ovarian microenvironment, thus affecting the normal function of the ovary. Our results indicate that HO-1 acts as a cytoprotective enzyme and plays a protective role in heat-induced apoptosis of bGCs. In conclusion, HO-1 and its metabolite CO inhibit the apoptosis of bGCs induced by heat stress through the ERK1/2 pathway. The results of this study provide a valuable clue for improving the fertility of heat stressed cows in summer. 相似文献
9.
10.
A simple phosphorescence method is proposed for quercetin detection based on Al3+-amplified room-temperature phosphorescence (RTP) signals of 3-mercaptopropionic acid (MPA)-capped Mn-doped ZnS quantum dots (QDs). The sensor was established based on some properties as follows. Al3+ can interact with carboxyl groups on the surface of MPA-capped Mn-doped ZnS QDs via chelation, which will lead to the aggregation of QDs and amplification of RTP signals, After the addition of quercetin, it can form more stable complex with Al3+ in alkaline aqueous solution and dissociate Al3+ from the surface of Mn-doped ZnS QDs, which will result in significant recovery of RTP intensity of the MPA-capped Mn-doped ZnS–Al3+ system. Under the optimized conditions, the change of RTP intensity was proportional to the concentration of quercetin in the range from 0.1 to 6.0 mg L−1, with a high correlation coefficient of 0.996 and a detection limit of 0.047 mg L−1. The proposed method is potentially suitable for detection of quercetin in real samples without complicated pretreatment. 相似文献