全文获取类型
收费全文 | 1121篇 |
免费 | 118篇 |
国内免费 | 56篇 |
出版年
2024年 | 5篇 |
2023年 | 17篇 |
2022年 | 34篇 |
2021年 | 50篇 |
2020年 | 42篇 |
2019年 | 51篇 |
2018年 | 66篇 |
2017年 | 34篇 |
2016年 | 60篇 |
2015年 | 71篇 |
2014年 | 74篇 |
2013年 | 80篇 |
2012年 | 95篇 |
2011年 | 95篇 |
2010年 | 57篇 |
2009年 | 57篇 |
2008年 | 51篇 |
2007年 | 49篇 |
2006年 | 46篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 28篇 |
2002年 | 26篇 |
2001年 | 26篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 8篇 |
1991年 | 13篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 3篇 |
排序方式: 共有1295条查询结果,搜索用时 15 毫秒
41.
Weiwei Zhou Fang Yan Jinzhong Fu Shifang Wu Robert W. Murphy Jing Che Yaping Zhang 《Molecular ecology》2013,22(1):130-142
Frequently, Pleistocene climatic cycling has been found to be the diver of genetic structuring in populations, even in areas that did not have continental ice sheets, such as on the Qinghai‐Tibetan Plateau (QTP). Typically, species distributed on the plateau have been hypothesized to re‐treat to south‐eastern refugia, especially during the Last Glacial Maximum (LGM). We evaluated sequence variation in the mitochondrial DNA gene Cytb and the nuclear DNA gene RAG‐1 in Rana kukunoris, a species endemic to the QTP. Two major lineages, N and S, were identified, and lineage N was further subdivided into N1 and N2. The geographical distribution and genealogical divergences supported the hypothesis of multiple refugia. However, major lineages and sublineages diverged prior to the LGM. Demographical expansion was detected only in lineage S and sublineage N2. Sublineage N1 might have survived several glacial cycles in situ and did not expand after the LGM because of the absence of suitable habitat; it survived in river islands. Genetic analysis and environment modelling suggested that the north‐eastern edge of QTP contained a major refugium for R. kukunoris. From here, lineage S dispersed southwards after the LGM. Two microrefugia in northern Qilian Mountains greatly contributed to current level of intraspecific genetic diversity. These results were found to have important implications for the habitat conservation in Northwest China. 相似文献
42.
A Genomic Islands (GI) is a chunk of DNA sequence in a genome whose origin can be traced back to other organisms or viruses.
The detection of GIs plays an indispensable role in biomedical research, due to the fact that GIs are highly related to special
functionalities such as disease-causing GIs - pathogenicity islands. It is also very important to visualize genomic islands, as well as
the supporting features corresponding to the genomic islands in the genome. We have developed a program, Genomic Island
Visualization (GIV), which displays the locations of genomic islands in a genome, as well as the corresponding supportive feature
information for GIs. GIV was implemented in C++, and was compiled and executed on Linux/Unix operating systems.
Availability
GIV is freely available for non-commercial use at http://www5.esu.edu/cpsc/bioinfo/software/GIV 相似文献43.
Wenliang Xiang Ke Li Seng Liu Yage Xing Mingyuan Li Zhenming Che 《World journal of microbiology & biotechnology》2013,29(3):559-567
The community succession of microbes inhabited in the fermenting lees of Luzhou-flavor liquor was investigated based on small-subunit rRNA culture independent method. All sequences recovered from fermenting lees respectively fell into the genera of Lactobacillus, Streptococcus, Bacillus, Staphylococcus, Clostridium, Pelobacter, Actobacter, Serratia, Burkholderia, Rhodoccous, Corynebacterium, Arthrobacter, Microbacterium, Curtobacterium, Leptotrichia, Methanocuuleus, Saccharomyces, Zygosaccharomyces, Saccharomycopsis, Pichia, Talaromyces, Aspergillus, Eurotium, Fomitopsis and Trichosporon. The fungal Pichia, Saccharomycopsis and Talaromyces were most abundant in the lees fermented for 1 day, the fungal Eurotium and the bacteria Burkholderia, Streptococcus and Lactobacillus were dominant in the lees fermented for 7 days, only the bacteria Lactobacillus, Burkholderia were prevalent in the lees fermented for 60 days. Most genera almost existed in the fermenting lees, while their distributions were significantly different in 1, 7 and 60 days fermented lees. The prokaryotic community similarity coefficient was from 0.5000 to 0.5455 and followed to 0.1523, and that of eukaryotic community was from 0.5466 to 0.5259 and to 0.3750 when compared at species level. These results suggested that many microbes in lees have community successions associated with fermenting and that such successions maybe contribute the fermentation process of Luzhou-flavor liquor and is main reasons that the characteristic flavor factors are produced. 相似文献
44.
Chiou‐Chu Su Chung Jan Chang Che‐Ming Chang Hsien‐Tzung Shih Kuo‐Ching Tzeng Fuh‐Jyh Jan Chin‐Wen Kao Wen‐Ling Deng 《Journal of Phytopathology》2013,161(6):389-396
Characteristic symptoms of Pierce's disease (PD) in grapevines (Vitis vinifera L.) were observed in 2002 in the major grape production fields of central Taiwan. Disease severity in vineyards varied, and all investigated grape cultivars were affected. Diseased tissues were collected from fields for subsequent isolation and characterization of the causal agent of the disease (Xylella fastidiosa). Koch's postulates were fulfilled by artificially inoculating two purified PD bacteria to grape cultivars Kyoho, Honey Red and Golden Muscat. The inoculated plants developed typical leaf‐scorching symptoms, and similar disease severity developed in the three cultivars from which the bacterium was readily re‐isolated, proving that the leaf scorch of grapevines in Taiwan is caused by the fastidious X. fastidiosa. This confirmed PD of grapevines is also the first report from the Asian Continent. Phylogenetic analyses were performed by comparing the 16S rRNA gene and 16S‐23S rRNA internal transcribed spacer region (16S‐23S ITS) of 12 PD strains from Taiwan with the sequences of 13 X. fastidiosa strains from different hosts and different geographical areas. Results showed that the PD strains of Taiwan were closely related to the American X. fastidiosa grape strains but not to the pear strains of Taiwan, suggesting that the X. fastidiosa grape and pear strains of Taiwan may have evolved independently from each other. 相似文献
45.
46.
47.
48.
Yuqin Shen Haoming Song Wenlin Ma Zhu Gong Yi Ni Xiaoyu Zhang Wenjun Xu Jinfa Jiang Lin Che Jiahong Xu Wenwen Yan Lin Zhou Guanghe Li Qiping Zhang Lemin Wang 《PloS one》2016,11(1)
Background
Cardiopulmonary exercise testing has been widely used to risk stratify patients with chronic heart failure (CHF). Peak oxygen consumption (peakVO2) was regarded as a powerful predictor of survival, as it is a surrogate for peak cardiac output (CO), which by most is considered the “true” measure of heart failure. Therefore, it is reasonable to hypothesize that CO is an even stronger predictor than peak VO2. The present study is aimed to investigate the prognostic value of peak cardiac power output (peak CPO) in comparison with peakVO2 in Chinese patients with CHF.Methods
Participants provided written informed consent to participate in this study. Totally 129 patients with CHF underwent symptom-limited cardiopulmonary exercise testing (CPET), with mean age 59.1±11.4 years, 87.6% male, 57.4% ischemic etiology, body mass index (BMI) 24.7±3.7 kg/m2 and LVEF 38±9%. CO was measured using an inert gas rebreathing method. The primary endpoints are cardiac deaths.Results
Over median 33.7-month follow-up, 19 cardiac deaths were reported. Among peak VO2,VE/VCO2 slope and Peak CPO, their area under ROC were 0.64, 0.67, 0.68, respectively (Ρ<0.05).The optimal thresholds for predicting cardiac deaths were peak VO2≤13.4 ml.kg-1.min-1, and VE/VCO2 slope≥39.3 and peak CPO≤ 1.1 respectively by ROC analysis. Finally, in patients with a peak VO2≤13.4 ml.kg-1.min-1 those with peak CPO>1.1W had better survival than those with peak CPO ≤ 1.1W. However, by multivariate analysis adjusted for age, sex, BMI, resting heart rate, LVMI, LVEF, Peak CPO was not an independent predictor of cardiac deaths (P> 0.05).Conclusions
Peak CPO was not a predictor of cardiac death in Chinese CHF patients. 相似文献49.
Chun Fu Lin Sanford P. C. Hsu Chung Jung Lin Wan Yuo Guo Chih Hsiang Liao Wei Fa Chu Sheng Che Hung Yang Shin Shih Yen Tzu Lin 《PloS one》2016,11(3)
Purpose
We sought to imitate angiographic cerebral circulation time (CCT) and create a similar index from baseline CT perfusion (CTP) to better predict vasospasm in patients with subarachnoid hemorrhage (SAH).Methods
Forty-one SAH patients with available DSA and CTP were retrospectively included. The vasospasm group was comprised of patients with deterioration in conscious functioning and newly developed luminal narrowing; remaining cases were classified as the control group. The angiography CCT (XA-CCT) was defined as the difference in TTP (time to peak) between the selected arterial ROIs and the superior sagittal sinus (SSS). Four arterial ROIs were selected to generate four corresponding XA-CCTs: the right and left anterior cerebral arteries (XA-CCTRA2 and XA-CCTLA2) and right- and left-middle cerebral arteries (XA-CCTRM2 and XA-CCTLM2). The CCTs from CTP (CT-CCT) were defined as the differences in TTP from the corresponding arterial ROIs and the SSS. Correlations of the different CCTs were calculated and diagnostic accuracy in predicting vasospasm was evaluated.Results
Intra-class correlations ranged from 0.96 to 0.98. The correlations of XA-CCTRA2, XA-CCTRM2, XA-CCTLA2, and XA-CCTLM2 with the corresponding CT-CCTs were 0.64, 0.65, 0.53, and 0.68, respectively. All CCTs were significantly prolonged in the vasospasm group (5.8–6.4 s) except for XA-CCTLA2. CT-CCTA2 of 5.62 was the optimal cut-off value for detecting vasospasm with a sensitivity of 84.2% and specificity 82.4%Conclusion
CT-CCTs can be used to interpret cerebral flow without deconvolution algorithms, and outperform both MTT and TTP in predicting vasospasm risk. This finding may help facilitate management of patients with SAH. 相似文献50.