全文获取类型
收费全文 | 25582篇 |
免费 | 2205篇 |
国内免费 | 2723篇 |
专业分类
30510篇 |
出版年
2024年 | 65篇 |
2023年 | 237篇 |
2022年 | 629篇 |
2021年 | 977篇 |
2020年 | 859篇 |
2019年 | 999篇 |
2018年 | 983篇 |
2017年 | 785篇 |
2016年 | 995篇 |
2015年 | 1525篇 |
2014年 | 1871篇 |
2013年 | 2024篇 |
2012年 | 2438篇 |
2011年 | 2269篇 |
2010年 | 1496篇 |
2009年 | 1329篇 |
2008年 | 1755篇 |
2007年 | 1480篇 |
2006年 | 1370篇 |
2005年 | 1122篇 |
2004年 | 1100篇 |
2003年 | 991篇 |
2002年 | 884篇 |
2001年 | 397篇 |
2000年 | 294篇 |
1999年 | 241篇 |
1998年 | 227篇 |
1997年 | 148篇 |
1996年 | 146篇 |
1995年 | 142篇 |
1994年 | 109篇 |
1993年 | 87篇 |
1992年 | 75篇 |
1991年 | 59篇 |
1990年 | 40篇 |
1989年 | 58篇 |
1988年 | 37篇 |
1987年 | 35篇 |
1986年 | 31篇 |
1985年 | 28篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1980年 | 7篇 |
1976年 | 8篇 |
1973年 | 7篇 |
1971年 | 6篇 |
1969年 | 9篇 |
1967年 | 8篇 |
1965年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
51.
MAPping Kinase Regulation of ICE1 in Freezing Tolerance 总被引:1,自引:0,他引:1
52.
53.
54.
Sunkyung Lee Kyu Yang Yi Sung Jun Youn Byung Ho Lee Sung-eun Yoo 《Bioorganic & medicinal chemistry letters》2009,19(5):1329-1331
A series of (2-aryl-5-methylimidazol-4-ylcarbonyl)guanidines and (2-aryl-5-methyloxazol-4-ylcarbonyl)guanidines were synthesized and evaluated as NHE-1 inhibitors. The structure–activity relationships well matched those of furan derivatives, which were previously investigated. The (2,5-disubstituted)phenyl compounds showed better activities than the other analogues in both imidazole and oxazole compounds. Especially, 2-(2,5-dichlorophenyl)imidazole 52, and 2-(2-methoxy-5-chlorophenyl)imidazole 54 compounds exhibited potent cardioprotective efficacy both in vitro and in vivo as well as high NHE-1 inhibitory activities. 相似文献
55.
The dysregulation of miR-137 plays vital roles in the oncogenesis and progression of various types of cancer, but its role in prognosis of gastric cancer patients remains unknown. This study was designed to investigate the expression and prognostic significance of miR-137 in gastric cancer patients after radical gastrectomy. Quantitative real-time PCR (qRT-PCR) was performed to evaluate the expression of miR-137 in human gastric cancer cell lines and tissues in patients with gastric adenocarcinoma. Results were assessed for association with clinical factors and overall survival by using Kaplan-Meier analysis. Prognostic values of miR-137 expression and clinical outcomes were evaluated by Cox regression analysis. The results exhibited that the expression level of miR-137 was decreased in human gastric cancer cell lines and tissues, and down-regulated expression of miR-137 was associated with tumor cell differentiation, N stage, and TNM stage. Decreased miR-137 expression in gastric cancer tissues was positively correlated with poor overall survival of gastric cancer patients. Further multivariate Cox regression analysis suggested that miR-137 expression was an independent prognostic indicator for gastric cancer except for TNM stage. Applying the prognostic value of miR-137 expression to TNM stage III group showed a better risk stratification for overall survival. In conclusion, the results reinforced the critical role for the down-regulated miR-137 expression in gastric cancer and suggested that miR-137 expression could be a prognostic indicator for this disease. In addition, these patients with TNM stage III gastric cancer and low miR-137 expression might need more aggressive postoperative treatment and closer follow-up. 相似文献
56.
Background
Extracting biological information from high-density Affymetrix arrays is a multi-step process that begins with the accurate annotation of microarray probes. Shortfalls in the original Affymetrix probe annotation have been described; however, few studies have provided rigorous solutions for routine data analysis. 相似文献57.
During the submerged fermentation of medicinal mushroom Chinese truffle Tuber sinense, there was no significant effect of metal ion on the cell growth and the production of intracellular polysaccharides, while metal ion and its concentration significantly affected the production of extracellular polysaccharides (EPS). By using the approach of "one-variable-at-a-time", 50 mM Mg2+ was identified to be the most favorable for EPS production, and the next was 10 mM K+. A mathematical model, constructed by response surface methodology combination with full factorial design, was applied to study the synergic effect of Mg2+ and K+. EPS production reached its peak value of 5.86 g/L under their optimal combination of 30 mM Mg2+ and 5 mM K+ predicted by the model, which was higher by 130.7% compared with the basal fermentation medium without metal ion. The validation experiment showed the experimental values agreed with the predicted values well. EPS production obtained in this work was the highest reported in the culture of T. sinense. 相似文献
58.
Lee MH Han DW Woo YI Uzawa M Park JC 《Journal of microbiology and biotechnology》2008,18(7):1274-1277
The inactivating efficiency of alternating high-voltage pulsed (AHVP) current was investigated in brine (20 w/v% NaCl) and saline (0.9 w/v% NaCl) inoculated with 1x 107 cells/ml of Listeria monocytogenes. AHVP current at 12 V with 1 pulse completely inactivated L. monocytogenes in brine within 3 ms, while the bacteria in saline were fully inactivated by 10-pulsed electric treatment at 12 V within the same time. Electron microscopic observation demonstrated substantial structural damage of electrically treated L. monocytogenes in brine. These results suggest that AHVP treatment would be effective for the rapid and complete inactivation of L. monocytogenes in brine or saline solution. 相似文献
59.
Jun Huang Yuttapong Thawornwattana Tom Flouri James Mallet Ziheng Yang 《Molecular biology and evolution》2022,39(12)
Genomic sequence data provide a rich source of information about the history of species divergence and interspecific hybridization or introgression. Despite recent advances in genomics and statistical methods, it remains challenging to infer gene flow, and as a result, one may have to estimate introgression rates and times under misspecified models. Here we use mathematical analysis and computer simulation to examine estimation bias and issues of interpretation when the model of gene flow is misspecified in analysis of genomic datasets, for example, if introgression is assigned to the wrong lineages. In the case of two species, we establish a correspondence between the migration rate in the continuous migration model and the introgression probability in the introgression model. When gene flow occurs continuously through time but in the analysis is assumed to occur at a fixed time point, common evolutionary parameters such as species divergence times are surprisingly well estimated. However, the time of introgression tends to be estimated towards the recent end of the period of continuous gene flow. When introgression events are assigned incorrectly to the parental or daughter lineages, introgression times tend to collapse onto species divergence times, with introgression probabilities underestimated. Overall, our analyses suggest that the simple introgression model is useful for extracting information concerning between-specific gene flow and divergence even when the model may be misspecified. However, for reliable inference of gene flow it is important to include multiple samples per species, in particular, from hybridizing species. 相似文献
60.
Robert‐Jan Bleichrodt G. Jerre van Veluw Brand Recter Jun‐ichi Maruyama Katsuhiko Kitamoto Han A. B. Wösten 《Molecular microbiology》2012,86(6):1334-1344
Hyphae of higher fungi are compartmentalized by septa. These septa contain a central pore that allows for inter‐compartmental and inter‐hyphal cytoplasmic streaming. The cytoplasm within the mycelium is therefore considered to be a continuous system. In this study, however, we demonstrate by laser dissection that 40% of the apical septa of exploring hyphae of Aspergillus oryzae are closed. Closure of septa correlated with the presence of a peroxisome‐derived organelle, known as Woronin body, near the septal pore. The location of Woronin bodies in the hyphae was dynamic and, as a result, plugging of the septal pore was reversible. Septal plugging was abolished in a ΔAohex1 strain that cannot form Woronin bodies. Notably, hyphal heterogeneity was also affected in the ΔAohex1 strain. Wild‐type strains of A. oryzae showed heterogeneous distribution of GFP between neighbouring hyphae at the outer part of the colony when the reporter was expressed from the promoter of the glucoamylase gene glaA or the α‐glucuronidase gene aguA. In contrast, GFP fluorescence showed a normal distribution in the case of the ΔAohex1 strain. Taken together, it is concluded that Woronin bodies maintain hyphal heterogeneity in a fungal mycelium by impeding cytoplasmic continuity. 相似文献