全文获取类型
收费全文 | 2562篇 |
免费 | 207篇 |
国内免费 | 306篇 |
专业分类
3075篇 |
出版年
2024年 | 9篇 |
2023年 | 68篇 |
2022年 | 140篇 |
2021年 | 202篇 |
2020年 | 117篇 |
2019年 | 167篇 |
2018年 | 143篇 |
2017年 | 94篇 |
2016年 | 134篇 |
2015年 | 148篇 |
2014年 | 178篇 |
2013年 | 205篇 |
2012年 | 241篇 |
2011年 | 212篇 |
2010年 | 130篇 |
2009年 | 101篇 |
2008年 | 131篇 |
2007年 | 121篇 |
2006年 | 103篇 |
2005年 | 78篇 |
2004年 | 69篇 |
2003年 | 63篇 |
2002年 | 53篇 |
2001年 | 27篇 |
2000年 | 32篇 |
1999年 | 26篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有3075条查询结果,搜索用时 0 毫秒
131.
132.
Maryna Perepelyuk LiKang Chin Xuan Cao Anne van Oosten Vivek B. Shenoy Paul A. Janmey Rebecca G. Wells 《PloS one》2016,11(1)
Tissues including liver stiffen and acquire more extracellular matrix with fibrosis. The relationship between matrix content and stiffness, however, is non-linear, and stiffness is only one component of tissue mechanics. The mechanical response of tissues such as liver to physiological stresses is not well described, and models of tissue mechanics are limited. To better understand the mechanics of the normal and fibrotic rat liver, we carried out a series of studies using parallel plate rheometry, measuring the response to compressive, extensional, and shear strains. We found that the shear storage and loss moduli G’ and G” and the apparent Young''s moduli measured by uniaxial strain orthogonal to the shear direction increased markedly with both progressive fibrosis and increasing compression, that livers shear strain softened, and that significant increases in shear modulus with compressional stress occurred within a range consistent with increased sinusoidal pressures in liver disease. Proteoglycan content and integrin-matrix interactions were significant determinants of liver mechanics, particularly in compression. We propose a new non-linear constitutive model of the liver. A key feature of this model is that, while it assumes overall liver incompressibility, it takes into account water flow and solid phase compressibility. In sum, we report a detailed study of non-linear liver mechanics under physiological strains in the normal state, early fibrosis, and late fibrosis. We propose a constitutive model that captures compression stiffening, tension softening, and shear softening, and can be understood in terms of the cellular and matrix components of the liver. 相似文献
133.
硝化是目前废水生物脱氮中应用最为广泛的工艺之一,其功能菌为化能自养型细菌,生长缓慢,对重金属十分敏感。砷是一种剧毒的类金属元素,主要以无机形式的亚砷酸盐[AsO2-,As(Ⅲ)]和砷酸盐[AsO43-,As(Ⅴ)]存在,尤以As(Ⅲ)毒性最强。但研究发现,在硝化体系中,高浓度As(Ⅲ)(约400mg/L)未对硝化功能微生物产生明显毒性。深入比较发现,As(Ⅲ)的生物氧化与硝化过程具有一定的关联性。化能自养型As(Ⅲ)氧化菌不仅可在有氧条件下将As(Ⅲ)氧化,还可在缺氧条件下以NO2–或NO3–为电子受体氧化As(Ⅲ)。而硝化细菌也是典型的化能自养菌,且硝化体系内存在氧气及硝化产物NO2–、NO3–等电子受体,理论上均可接受电子实现As(Ⅲ)的氧化。本文结合硝化反应特性,综述了As(Ⅲ)在硝化体系下的解毒机制,主要为胞外聚合物的... 相似文献
134.
Dongchao Xu Ajuan Liu Xuan Wang Ming Zhang Zunyi Zhang Zhou Tan Mengsheng Qiu 《Developmental neurobiology》2018,78(1):39-50
Accurate quantification of gene expression is fundamental for understanding the molecular, genetic and functional bases of tissue development and diseases. Quantitative real‐time PCR (qPCR) is now the most widely used method of quantifying gene expression due to its simplicity, specificity, sensitivity, and wide quantification range. The use of appropriate reference genes to ensure accurate normalization is crucial for the correct quantification of gene expression from the early development, maturation, aging to injury processes in the central nervous system (CNS). In this study, we have determined the expression profiles of 12 candidate housekeeping genes (ACTB, CYC1, HMBS, GAPDH, HPRT1, RPL13A, YWHAZ, PPIA, RPLP0, TFRC, GUS, and 18S rRNA) in developing mouse brain and spinal cord. Throughout development, there was a significant degree of fluctuations in their expression levels, indicating the importance and complexity of finding appropriate reference genes. Three software including BestKeeper, geNorm and NormFinder were used to evaluate the stability of potential reference genes. GUS was the most stable gene and GUS/YWHAZ were the most stable reference gene pair across different developmental stages in different CNS regions, whereas HPRT1 and GAPDH were the most variable genes and thus inappropriate to use as reference genes. Therefore, our results identified GUS and YWHAZ as the best combination of two reference genes for expression data normalization in CNS developmental studies. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 39–50, 2018 相似文献
135.
Development and evaluation of an enzyme-linked immunosorbent assay with recombinant SAG2 for diagnosis of Toxoplasma gondii infection in cats 总被引:7,自引:0,他引:7
Huang X Xuan X Kimbita EN Battur B Miyazawa T Fukumoto S Mishima M Makala LH Suzuki H Sugimoto C Nagasawa H Fujisaki K Mikami T Igarashi I 《The Journal of parasitology》2002,88(4):804-807
Cats are pivotal in the transmission of Toxoplasma gondii. To develop a sensitive and specific serodiagnostic method for feline toxoplasmosis, surface antigen 2 (SAG2) of T. gondii was expressed in Escherichia coli and its diagnostic potential evaluated in an enzyme-linked immunosorbent assay (ELISA). The ELISA with recombinant SAG2 (rSAG2) was able to differentiate very clearly between sera from cats experimentally infected with T. gondii and sera from normal cats. Serum samples collected from domestic cats in Japan were investigated by the ELISA, and the results were compared with those of a commercially available latex agglutination test (LAT) kit. Of the 192 samples screened, 42 (21.9%) were positive by ELISA. Among the 42 ELISA-positive samples, 39 were positive by LAT. There was a significant correlation between ELISA and LAT titers. All the 150 ELISA-negative samples were negative by LAT. These results indicate that the ELISA with rSAG2 expressed in E. coli should be a useful method for detection of T. gondii infection in cats. 相似文献
136.
Zekun Huang Wanlong Huang Xiaolin Liu Zhaofang Han Guangjian Liu Grace Afumwaa Boamah Yi Wang Feng Yu Yang Gan Qizhen Xiao Xuan Luo Nan Chen Meng Liu Weiwei You Caihuan Ke 《Molecular ecology resources》2022,22(1):15-27
The nautilus, commonly known as a “living fossil,” is endangered and may be at risk of extinction. The lack of genomic information hinders a thorough understanding of its biology and evolution, which can shed light on the conservation of this endangered species. Here, we report the first high-quality chromosome-level genome assembly of Nautilus pompilius. The assembled genome size comprised 785.15 Mb. Comparative genomic analyses indicated that transposable elements (TEs) and large-scale genome reorganizations may have driven lineage-specific evolution in the cephalopods. Remarkably, evolving conserved genes and recent TE insertion activities were identified in N. pompilius, and we speculate that these findings reflect the strong adaptability and long-term survival of the nautilus. We also identified gene families that are potentially responsible for specific adaptation and evolution events. Our study provides unprecedented insights into the specialized biology and evolution of N. pompilius, and the results serve as an important resource for future conservation genomics of the nautilus and closely related species. 相似文献
137.
138.
139.
Xuan Pan Madhusudhan Papasani Yi Hao Marco Calamito Fang Wei William J Quinn Arindam Basu Junwen Wang Suchita Hodawadekar Kristina Zaprazna Huifei Liu Yang Shi David Allman Michael Cancro Michael L Atchison 《The EMBO journal》2013,32(8):1168-1182
Conditional knock‐out (KO) of Polycomb Group (PcG) protein YY1 results in pro‐B cell arrest and reduced immunoglobulin locus contraction needed for distal variable gene rearrangement. The mechanisms that control these crucial functions are unknown. We deleted the 25 amino‐acid YY1 REPO domain necessary for YY1 PcG function, and used this mutant (YY1ΔREPO), to transduce bone marrow from YY1 conditional KO mice. While wild‐type YY1 rescued B‐cell development, YY1ΔREPO failed to rescue the B‐cell lineage yielding reduced numbers of B lineage cells. Although the IgH rearrangement pattern was normal, there was a selective impact at the Igκ locus that showed a dramatic skewing of the expressed Igκ repertoire. We found that the REPO domain interacts with proteins from the condensin and cohesin complexes, and that YY1, EZH2 and condensin proteins co‐localize at numerous sites across the Ig kappa locus. Knock‐down of a condensin subunit protein or YY1 reduced rearrangement of Igκ Vκ genes suggesting a direct role for YY1‐condensin complexes in Igκ locus structure and rearrangement. 相似文献
140.
Nguyen Phuong Thao Le Duc Dat Ninh Thi Ngoc Vu Anh Tu Tran Thi Hong Hanh Phan Thi Thanh Huong Nguyen Xuan Nhiem Bui Huu Tai Nguyen Xuan Cuong Nguyen Hoai Nam Pham Van Cuong Seo Young Yang Sohyun Kim Doobyeong Chae Young-Sang Koh Phan Van Kiem Chau Van Minh Young Ho Kim 《Bioorganic & medicinal chemistry letters》2013,23(6):1823-1827
Three new pyrrole oligoglycosides, astebatheriosides A–C (1–3), and a new furan oligoglycoside, astebatherioside D (4), were isolated from the starfish Asterina batheri by various chromatographic methods. Their structures were elucidated by spectroscopic and chemical methods. Compounds 2, 3, and 4 moderately inhibited IL-12 p40 production in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs) with IC50 values of 36.4, 31.6, and 22.8 μM, respectively. 相似文献