全文获取类型
收费全文 | 3777篇 |
免费 | 340篇 |
国内免费 | 326篇 |
出版年
2024年 | 4篇 |
2023年 | 44篇 |
2022年 | 99篇 |
2021年 | 200篇 |
2020年 | 131篇 |
2019年 | 165篇 |
2018年 | 155篇 |
2017年 | 123篇 |
2016年 | 184篇 |
2015年 | 224篇 |
2014年 | 248篇 |
2013年 | 280篇 |
2012年 | 319篇 |
2011年 | 289篇 |
2010年 | 185篇 |
2009年 | 165篇 |
2008年 | 205篇 |
2007年 | 154篇 |
2006年 | 167篇 |
2005年 | 145篇 |
2004年 | 136篇 |
2003年 | 107篇 |
2002年 | 116篇 |
2001年 | 97篇 |
2000年 | 85篇 |
1999年 | 79篇 |
1998年 | 46篇 |
1997年 | 44篇 |
1996年 | 38篇 |
1995年 | 34篇 |
1994年 | 28篇 |
1993年 | 21篇 |
1992年 | 19篇 |
1991年 | 23篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有4443条查询结果,搜索用时 15 毫秒
141.
142.
143.
Carola Ledderose Marco M. Hefti Yu Chen Yi Bao Thomas Seier Linglin Li Tobias Woehrle Jingping Zhang Wolfgang G. Junger 《Purinergic signalling》2016,12(4):673-685
In neutrophils, adenosine triphosphate (ATP) release and autocrine purinergic signaling regulate coordinated cell motility during chemotaxis. Here, we studied whether similar mechanisms regulate the motility of breast cancer cells. While neutrophils and benign human mammary epithelial cells (HMEC) form a single leading edge, MDA-MB-231 breast cancer cells possess multiple leading edges enriched with A3 adenosine receptors. Compared to HMEC, MDA-MB-231 cells overexpress the ectonucleotidases ENPP1 and CD73, which convert extracellular ATP released by the cells to adenosine that stimulates A3 receptors and promotes cell migration with frequent directional changes. However, exogenous adenosine added to breast cancer cells or the A3 receptor agonist IB-MECA dose-dependently arrested cell motility by simultaneous stimulation of multiple leading edges, doubling cell surface areas and significantly reducing migration velocity by up to 75 %. We conclude that MDA-MB-231 cells, HMEC, and neutrophils differ in the purinergic signaling mechanisms that regulate their motility patterns and that the subcellular distribution of A3 adenosine receptors in MDA-MB-231 breast cancer cells contributes to dysfunctional cell motility. These findings imply that purinergic signaling mechanisms may be potential therapeutic targets to interfere with the motility of breast cancer cells in order to reduce the spread of cancer cells and the risk of metastasis. 相似文献
144.
Suppressive effect of epigallocatechin‐3‐O‐gallate on endoglin molecular regulation in myocardial fibrosis in vitro and in vivo
下载免费PDF全文
![点击此处可从《Journal of cellular and molecular medicine》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Chiu‐Mei Lin Hang Chang Bao‐Wei Wang Kou‐Gi Shyu 《Journal of cellular and molecular medicine》2016,20(11):2045-2055
Epigallocatechin‐3‐O‐gallate (EGCG), derived from green tea, has been studied extensively because of its diverse physiological and pharmacological properties. This study evaluates the protective effect of EGCG on angiotensin II (Ang II)‐induced endoglin expression in vitro and in vivo. Cardiac fibroblasts (CFs) from the thoracic aorta of adult Wistar rats were cultured and induced with Ang II. Western blotting, Northern blotting, real‐time PCR and promoter activity assay were performed. Ang II increased endoglin expression significantly as compared with control cells. The specific extracellular signal‐regulated kinase inhibitor SP600125 (JNK inhibitor), EGCG (100 μM) and c‐Jun N‐terminal kinase (JNK) siRNA attenuated endoglin proteins following Ang II induction. In addition, pre‐treated Ang II‐induced endoglin with EGCG diminished the binding activity of AP‐1 by electrophoretic mobility shift assay. Moreover, the luciferase assay results revealed that EGCG suppressed the endoglin promoter activity in Ang II‐induced CFs by AP‐1 binding. Finally, EGCG and the JNK inhibitor (SP600125) were found to have attenuated endoglin expression significantly in Ang II‐induced CFs, as determined through confocal microscopy. Following in vivo acute myocardial infarction (AMI)‐related myocardial fibrosis study, as well as immunohistochemical and confocal analyses, after treatment with endoglin siRNA and EGCG (50 mg/kg), the area of myocardial fibrosis reduced by 53.4% and 64.5% and attenuated the left ventricular end‐diastolic and systolic dimensions, and friction shortening in hemodynamic monitor. In conclusion, epigallocatechin‐3‐O‐gallate (EGCG) attenuated the endoglin expression and myocardial fibrosis by anti‐inflammatory effect in vitro and in vivo, the novel suppressive effect was mediated through JNK/AP‐1 pathway. 相似文献
145.
Are pets associated with happiness in their owners? Some research has demonstrated positive connections between pets and the physical health of their owners, and more recently, research has shown the beneficial effects of pets on the negative aspects of mental health as well. However, much less research has focused on the relation between pets and the positive aspects of mental health, such as happiness. In the current study, 263 American adults completed an online survey using Amazon Mechanical Turk. Results indicate that pet owners were more satisfied with their lives than non-owners, but did not differ on other wellbeing measures, personality measures, emotion regulation, or need satisfaction. Dog owners scored higher on all aspects of wellbeing compared with cat owners, and differed on a number of other measures, including the Big Five personality traits, emotion regulation strategies, and need satisfaction. The relationship between type of pet owned and wellbeing was mediated by the Big Five personality traits (extraversion, agreeableness, and neuroticism, specifically), emotion regulation strategy, and need satisfaction. In addition, self-identified “dog people,” relative to “cat people,” showed similar patterns to those of dog owners, but the effects were often smaller and non-significant. Although there may not be many differences between those who own pets and those who do not, clearly owning a dog is associated with beneficial outcomes. Implications and future directions are discussed. 相似文献
146.
Pei‐ling Song Małgorzata Jȩdryczka Witold Irzykowski Meng‐jiao Yan Hai‐yan Huangfu Li‐fen Hao Yu‐ying Bao Zi‐qin Li 《Journal of Phytopathology》2016,164(11-12):1097-1104
An efficient DNA extraction protocol and polymerase chain reaction (PCR) assay for detecting Leptosphaeria maculans from infected seed lots of oilseed rape were developed. L. maculans, the causal agent of blackleg, a damaging disease in oilseeds rape/canola worldwide, was listed as a quarantine disease by China in 2009. China imports several millions of tons of oilseeds every year. So there is a high risk that this pathogen will be introduced to China via contaminated seeds. Seed contamination is one of the most significant factors in the global spread of phytopathogens. Detection of L. maculans in infected seed lots by PCR assay is difficult due to the low level of pathogen mycelium/spores on seeds and PCR inhibitors associated with the seeds of oilseed rape. In our study, these two major obstacles were overcome by the development of a two‐step extraction protocol combined with a nested PCR. This extraction protocol (kit extraction after CTAB method) can efficiently extract high‐quality DNA for PCR. Amplification results showed that the detection threshold for conventional PCR and nested PCR was, respectively, 1 ng and 10 fg of DNA per μl in mycelia samples. On contaminated seed lots of oilseed rape, the detection threshold of conventional and nested PCR was 709 fg/μl and 709 ag/μl of DNA, respectively. The DNA extraction protocol and PCR assay developed in this study can be used for rapid and reliable detection of L. maculans from infected seeds of oilseed rape . 相似文献
147.
High-level phenotypic variations in populations of Armeniaca sibirica in Nei Mongol,China北大核心CSCD
下载免费PDF全文
![点击此处可从《植物生态学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yin M.-Y.Jiang Z.-M.Zhu X.-C.Bao W.-Q.Zhao H.Wuyun T. 《植物生态学报》2016,(10):1090-1099
Aims: Our objectives were to determine the variations in phenotypic traits of Armeniaca sibirica populations and their spatial patterns. Methods: We used nested variation, coefficient of variation, multi-comparison, correlation analysis and principal component analysis to analyze the 23 phenotypic traits for 130 individuals in 13 populations of A. sibirica. Important findings: The results showed that there were significant differences in phenotypic variations among and within populations. The variation was greater among populations (47.15%) than within population (16.43%). The mean phenotypic differentiation coefficient was 73.03% among populations, indicating the variance among populations being the main source of the phenotypic variation. The average variation coefficient of 23 traits ranged from 7.01% to 27.23%, with an average of 14.28%. The variation coefficient of nutlet was highest (15.67%), and the variation coefficient of fruit was smallest (12.11%). The phenotypic diversity is highest in Wanjiagou Tumotezuoqi and smallest in Horqin, Right Front Banner Chaersen. Longitude, mean annual precipitation and sunshine duration were significantly correlated with major traits of phenotypic. The 13 populations could be divided into four groups according to the principal component analysis. Leaf traits of Wula Mountain and nutlet traits of Archorchin Banner were significantly correlated with ecological and geographic factors. 相似文献
148.
149.
Xing-Bao Feng Zi-Wen Zheng Xian Zhang Jun Gu Qi-Li Feng Li-Hua Huang 《Insect Science》2019,26(5):821-830
Silkworm mutants are valuable resources for both transgenic breeding and gene discovery. PiggyBac-based random insertional mutagenesis has been widely used in gene functional studies. In order to discover genes involved in silk synthesis, a piggyBac-based random insertional library was constructed using Bombyx mori, and the mutants with abnormal cocoon were particularly screened. By this means, a “thin cocoon” mutant was identified. This mutant revealed thinner cocoon shell and shorter posterior silk gland (PSG) compared with the wild type. The messenger RNA (mRNA) levels of all the three fibroin genes, including Fib-H, Fib-L and P25, were significantly down-regulated in the PSG of mutants. Four piggyBac insertion sites were identified in Aquaporin (AQP), Longitudinals lacking protein-like {Lola), Glutamyl aminopeptidase-like (GluAP) and Loc101744460. The mRNA levels of all the four genes were significantly altered in the silk gland of mutants. In particular, the mRNA amount of AQP, a gene responsible for the regulation of osmotic pressure, decreased dramatically immediately prior to the spinning stage in the anterior silk gland of mutants. The identification of the genes disrupted in the “thin cocoon” mutant in this study provided useful information for understanding silk production and transgenic breeding of silkworms in the future. 相似文献
150.
Tong Liu Wen-Qiang Yang Yu-Gu Xie Pei-Wen Liu Li-Hua Xie Feng Lin Chen-Ying Li Jin-Bao Gu Kun Wu Gui-Yun Yan Xiao-Guang Chen 《Insect Science》2019,26(6):1045-1054
Aedes (Stegomyia) albopictus, also known as the Asian tiger mosquito, is a mosquito which originated in Asia. In recent years, it has become increasingly rampant throughout the world. This mosquito can transmit several arboviruses, including dengue, Zika and chikungunya viruses, and is considered a public health threat. Despite the urgent need of genome engineering to analyze specific gene functions, progress in genetical manipulation of Ae. albopictus has been slow due to a lack of efficient methods and genetic markers. In the present study, we established targeted disruptions in two genes, kynurenine hydroxylase (kh) and dopachrome conversion enzyme (yellow), to analyze the feasibility of generating visible phenotypes with genome editing by the clustered regularly interspaced short palindromic repeats (CRISPR)/ CRISPR-associated protein 9 (Cas9) system in Ae. albopictus. Following Cas9 single guide RNA ribonucleoprotein injection into the posterior end of pre-blastoderm embryos, 30%-50% of fertile survivors produced alleles that failed to complement existing kh and yellow mutations. Complete eye and body pigmentation defects were readily observed in GI pupae and adults, indicating successful generation of highly heritable mutations. We conclude that the CRISPR/Cas9-mediated gene editing system can be used mAe. albopictus and that it can be adopted as an efficient tool for genome-scale analysis and biological study. 相似文献