全文获取类型
收费全文 | 2771篇 |
免费 | 245篇 |
国内免费 | 416篇 |
出版年
2024年 | 8篇 |
2023年 | 52篇 |
2022年 | 122篇 |
2021年 | 225篇 |
2020年 | 173篇 |
2019年 | 184篇 |
2018年 | 166篇 |
2017年 | 125篇 |
2016年 | 156篇 |
2015年 | 243篇 |
2014年 | 246篇 |
2013年 | 250篇 |
2012年 | 277篇 |
2011年 | 232篇 |
2010年 | 133篇 |
2009年 | 121篇 |
2008年 | 128篇 |
2007年 | 91篇 |
2006年 | 82篇 |
2005年 | 65篇 |
2004年 | 39篇 |
2003年 | 44篇 |
2002年 | 41篇 |
2001年 | 26篇 |
2000年 | 24篇 |
1999年 | 22篇 |
1998年 | 16篇 |
1997年 | 22篇 |
1996年 | 22篇 |
1995年 | 8篇 |
1994年 | 13篇 |
1993年 | 3篇 |
1992年 | 10篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有3432条查询结果,搜索用时 31 毫秒
991.
992.
p21-activated Kinase 6 (PAK6) is a serine/threonine kinase belonging to the p21-activated kinase (PAK) family. PAK kinases
are well-known regulators of a wide variety of cellular functions, including regulation of cytoskeleton rearrangement, cell
survival, apoptosis and the mitogen-activated protein kinase signaling pathway. To elucidate the expressions and possible
functions of PAK6 in central nervous system (CNS) lesion and repair, we performed a traumatic brain injury (TBI) model in
adult rats. Western blot analysis revealed that PAK6 level significantly increased at day 3 after damage, and then declined
during the following days. Besides, double immunofluorescence staining showed PAK6 was primarily expressed in the neurons
and a few of glial cells in the normal group. While after injury, the expression of PAK6 was increased significantly in the
astrocytes and neurons, and the astrocytes had largely proliferated. We also examined the expression of proliferating cell
nuclear antigen (PCNA) whose change was correlated with the expression of PAK6. Importantly, double immunofluorescence staining
revealed that cell proliferation evaluated by PCNA appeared in many PAK6-expressing cells at day 3 after injury. In addition,
injury-induced expression of PAK6 was co-labeled by active caspase-3 during neuronal apoptosis after injury. Collectively,
we hypothesized PAK6 may play important roles in CNS pathophysiology after TBI and further research is needed to have a good
understanding of its function and mechanism. 相似文献
993.
Plant protein-protein interaction networks have not been identified by large-scale experiments. In order to better understand the protein interactions in rice, the Predicted Rice Interactome Network (PRIN; http://bis.zju.edu.cn/prin/) presented 76,585 predicted interactions involving 5,049 rice proteins. After mapping genomic features of rice (GO annotation, subcellular localization prediction, and gene expression), we found that a well-annotated and biologically significant network is rich enough to capture many significant functional linkages within higher-order biological systems, such as pathways and biological processes. Furthermore, we took MADS-box domain-containing proteins and circadian rhythm signaling pathways as examples to demonstrate that functional protein complexes and biological pathways could be effectively expanded in our predicted network. The expanded molecular network in PRIN has considerably improved the capability of these analyses to integrate existing knowledge and provide novel insights into the function and coordination of genes and gene networks. 相似文献
994.
花梨木叶中鹰嘴豆芽素A的提取工艺研究 总被引:3,自引:3,他引:0
以花梨木的可再生资源—叶子为原料,利用微波辅助酶提取技术进行提取,在单因素试验的基础上对提取条件进行了考察,根据BBD(Box-Behnken design)实验设计原理,采用3因素3水平的响应面分析法,以花梨木叶子中主要异黄酮鹰嘴豆芽素A(biochanin A)为指标,对提取过程进行优化,得到最佳工艺参数为:提取时间15 min,微波辐射功率300 W,提取温度34℃,pH值5.2,酶的加入量3.5 mg.g-1。在最佳提取条件下,鹰嘴豆芽素A的提取率可达1.579 mg.g-1。 相似文献
995.
Cyclin-dependent kinase 6 (CDK6) is a key element of D-type cyclin holoenzymes. It is involved in the regulation of the G1-phase of the cell cycle and is considered to be an important candidate gene for selection of body measurement traits through marker-assisted selection. We cloned the promoter sequence of this gene in bovines and found it to share high similarity with that of the human CDK6 promoter. A 2271-bp sequence upstream of the start codon in the bovine CDK6 5'-flanking sequence is rich in GC; it lacks consensus TATA or CAAT box, but it contains several MZF1 binding sites. Other potential cis-regulatory elements were found in the 5'-flanking region, including CdxA, SRY, p300, GATA-1, and deltaE. Allele frequencies were also analyzed in various cattle breeds (Qinchuan, Qinchuan improvement steers, Nanyang, Jiaxian red, Xia'nan, Luxi, Simmental and Luxi crossbred steers, and Xuelong) and association with a selected single nucleotide polymorphism (SNP) was calculated. The T-1075C SNP in the promoter was found to be significantly associated with body length and heart girth. This SNP marker was found to be significantly associated with body length and the heart girth in 737 individuals. We conclude that this SNP of the CDK6 gene has potential as a genetic marker for important body traits in bovine reproduction and breeding. 相似文献
996.
Yao Z Yin P Su D Peng Z Zhou L Ma L Guo W Ma L Xu G Shi J Jiao B 《Molecular bioSystems》2011,7(9):2608-2614
Thyroid carcinoma is a common endocrine malignancy worldwide, accounting for approximately 1% of all diagnosed cancers and about 91.5% of the malignancies of head and neck. However, differentiating malignant thyroid nodules from benign ones remains a diagnostic challenge. Thus, novel molecular markers that enable non-invasive diagnostics for malignant thyroid nodules are urgently needed. In the present study, a metabonomic investigation based on liquid chromatography-LTQ Orbitrap mass spectrometry was employed for serum metabolic profiling of 30 cases of papillary thyroid carcinomas (PTC), 80 cases of nodular goiters (benign thyroid nodules) and 30 cases of healthy controls. According to the results of multivariate statistical data analysis, the significantly changed metabolites among these three groups were defined. It was found that most of these metabolites decreased in the sera of both malignant and benign thyroid cases due to the increased metabolic rate, which is in accordance with clinical features. The major metabolic differences between benign and malignant nodules occurred in lipid metabolism. Especially, the content of 3-hydroxybutyric acid, an intermediate product of fatty acid metabolism, was much higher in the PTC group than that in the nodule goiter and control groups, indicating its potential as a diagnostic marker for PTC and nodular goiters. These results show that the serum metabolic profiling method is a powerful tool for distinguishing thyroid carcinoma from nodular goiter and healthy controls. 相似文献
997.
998.
Cohen SS Gammon MD North KE Millikan RC Lange EM Williams SM Zheng W Cai Q Long J Smith JR Signorello LB Blot WJ Matthews CE 《Obesity (Silver Spring, Md.)》2011,19(10):2053-2062
Adiponectin is an adipose-secreted protein with influence on several physiologic pathways including those related to insulin sensitivity, inflammation, and atherogenesis. Adiponectin levels are highly heritable and several single-nucleotide polymorphisms (SNPs) in adiponectin-related genes (ADIPOQ, ADIPOR1, ADIPOR2) have been examined in relation to circulating adiponectin levels and obesity phenotypes, but despite differences in adiponectin levels and obesity prevalence by race, few studies have included black participants. Using cross-sectional interview data and blood samples collected from 990 black and 977 white women enrolled in the Southern Community Cohort Study (SCCS) from 2002 to 2006, we examined 25 SNPs in ADIPOQ, 19 in ADIPOR1, and 27 in ADIPOR2 in relation to serum adiponectin levels and BMI using race-stratified linear regression models adjusted for age and percentage African ancestry. SNP rs17366568 in ADIPOQ was significantly associated with serum adiponectin levels in white women only (adjusted mean adiponectin levels = 15.9 for G/G genotype, 13.7 for A/G, and 9.3 for A/A, P = 0.00036). No other SNPs were associated with adiponectin or BMI among blacks or whites. Because adiponectin levels as well as obesity are highly heritable and vary by race but associations with polymorphisms in the ADIPOQ, ADIPOR1, and ADIPOR2 genes have been few in this and other studies, future work including large populations from diverse racial groups is needed to detect additional genetic variants that influence adiponectin and BMI. 相似文献
999.
Modern science of networks has brought significant advances to our understanding of complex systems biology. As a representative model of systems biology, Protein Interaction Networks (PINs) are characterized by a remarkable modular structures, reflecting functional associations between their components. Many methods were proposed to capture cohesive modules so that there is a higher density of edges within modules than those across them. Recent studies reveal that cohesively interacting modules of proteins is not a universal organizing principle in PINs, which has opened up new avenues for revisiting functional modules in PINs. In this paper, functional clusters in PINs are found to be able to form unorthodox structures defined as bi-sparse module. In contrast to the traditional cohesive module, the nodes in the bi-sparse module are sparsely connected internally and densely connected with other bi-sparse or cohesive modules. We present a novel protocol called the BinTree Seeking (BTS) for mining both bi-sparse and cohesive modules in PINs based on Edge Density of Module (EDM) and matrix theory. BTS detects modules by depicting links and nodes rather than nodes alone and its derivation procedure is totally performed on adjacency matrix of networks. The number of modules in a PIN can be automatically determined in the proposed BTS approach. BTS is tested on three real PINs and the results demonstrate that functional modules in PINs are not dominantly cohesive but can be sparse. BTS software and the supporting information are available at: www.csbio.sjtu.edu.cn/bioinf/BTS/. 相似文献
1000.