全文获取类型
收费全文 | 110553篇 |
免费 | 8459篇 |
国内免费 | 6965篇 |
专业分类
125977篇 |
出版年
2024年 | 215篇 |
2023年 | 1451篇 |
2022年 | 3239篇 |
2021年 | 5476篇 |
2020年 | 3577篇 |
2019年 | 4375篇 |
2018年 | 4353篇 |
2017年 | 3230篇 |
2016年 | 4599篇 |
2015年 | 6677篇 |
2014年 | 7865篇 |
2013年 | 8315篇 |
2012年 | 9965篇 |
2011年 | 8875篇 |
2010年 | 5446篇 |
2009年 | 4747篇 |
2008年 | 5588篇 |
2007年 | 4924篇 |
2006年 | 4371篇 |
2005年 | 3331篇 |
2004年 | 2933篇 |
2003年 | 2531篇 |
2002年 | 2205篇 |
2001年 | 2001篇 |
2000年 | 1860篇 |
1999年 | 1842篇 |
1998年 | 1017篇 |
1997年 | 1137篇 |
1996年 | 1017篇 |
1995年 | 919篇 |
1994年 | 942篇 |
1993年 | 666篇 |
1992年 | 993篇 |
1991年 | 838篇 |
1990年 | 613篇 |
1989年 | 559篇 |
1988年 | 485篇 |
1987年 | 411篇 |
1986年 | 388篇 |
1985年 | 390篇 |
1984年 | 211篇 |
1983年 | 197篇 |
1982年 | 137篇 |
1981年 | 114篇 |
1980年 | 107篇 |
1979年 | 115篇 |
1978年 | 78篇 |
1977年 | 60篇 |
1974年 | 74篇 |
1972年 | 62篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Zhou J Ma Q Yi H Wang L Song H Yuan YJ 《Applied and environmental microbiology》2011,77(19):7023-7030
The metabolic cooperation in the ecosystem of Bacillus megaterium and Ketogulonicigenium vulgare was investigated by cultivating them spatially on a soft agar plate. We found that B. megaterium swarmed in a direction along the trace of K. vulgare on the agar plate. Metabolomics based on gas chromatography coupled with time-of-flight mass spectrometry (GC-TOF-MS) was employed to analyze the interaction mechanism between the two microorganisms. We found that the microorganisms interact by exchanging a number of metabolites. Both intracellular metabolism and cell-cell communication via metabolic cooperation were essential in determining the population dynamics of the ecosystem. The contents of amino acids and other nutritional compounds in K. vulgare were rather low in comparison to those in B. megaterium, but the levels of these compounds in the medium surrounding K. vulgare were fairly high, even higher than in fresh medium. Erythrose, erythritol, guanine, and inositol accumulated around B. megaterium were consumed by K. vulgare upon its migration. The oxidization products of K. vulgare, including 2-keto-gulonic acids (2KGA), were sharply increased. Upon coculturing of B. megaterium and K. vulgare, 2,6-dipicolinic acid (the biomarker of sporulation of B. megaterium), was remarkably increased compared with those in the monocultures. Therefore, the interactions between B. megaterium and K. vulgare were a synergistic combination of mutualism and antagonism. This paper is the first to systematically identify a symbiotic interaction mechanism via metabolites in the ecosystem established by two isolated colonies of B. megaterium and K. vulgare. 相似文献
922.
The ubiquitin-proteasome system (UPS) in plants, like in other eukaryotes, targets numerous intracellular regulators and thus modulates almost every aspect of growth and development. The well-known and best-characterized outcome of ubiquitination is mediating target protein degradation via the 26S proteasome, which represents the major selective protein degradation pathway conserved among eukaryotes. In this review, we will discuss the molecular composition, regulation and function of plant UPS, with a major focus on how DELLA protein degradation acts as a key in gibberellin signal transduction and its implication in the regulation of plant growth. 相似文献
923.
924.
Songwen Lin Chunyang Wang Ming Ji Deyu Wu Yuanhao Lv Li Sheng Fangbin Han Yi Dong Kehui Zhang Yakun Yang Yan Li Xiaoguang Chen Heng Xu 《Bioorganic & medicinal chemistry》2018,26(3):637-646
A series of new thienopyrimidine derivatives has been discovered as potent PI3K inhibitors. The systematic SAR studies for these analogues are described. Among them, 8a and 9a exhibit nanomolar enzymatic potencies and sub-micromolar cellular anti-proliferative activities. 8a displays favorable pharmacokinetic profiles, while 9a easily undergoes deacetylation to yield a major metabolite 8a. Furthermore, 8a and 9a potently inhibit tumor growth in a dose-dependent manner in the NCI-H460 xenograft model with an acceptable safety profile. 相似文献
925.
Mitochondrial unfolded protein response gene Clpp is required to maintain ovarian follicular reserve during aging,for oocyte competence,and development of pre‐implantation embryos 下载免费PDF全文
Tianren Wang Elnur Babayev Zongliang Jiang Guangxin Li Man Zhang Ecem Esencan Tamas Horvath Emre Seli 《Aging cell》2018,17(4)
Caseinolytic peptidase P mediates degradation of unfolded mitochondrial proteins and activates mitochondrial unfolded protein response (mtUPR) to maintain protein homeostasis. Clpp?/? female mice generate a lower number of mature oocytes and two‐cell embryos, and no blastocysts. Clpp?/? oocytes have smaller mitochondria, with lower aspect ratio (length/width), and decreased expression of genes that promote fusion. A 4‐fold increase in atretic follicles at 3 months, and reduced number of primordial follicles at 6–12 months are observed in Clpp?/? ovaries. This is associated with upregulation of p‐S6, p‐S6K, p‐4EBP1 and p‐AKT473, p‐mTOR2481 consistent with mTORC1 and mTORC2 activation, respectively, and Clpp?/? oocyte competence is partially rescued by mTOR inhibitor rapamycin. Our findings demonstrate that CLPP is required for oocyte and embryo development and oocyte mitochondrial function and dynamics. Absence of CLPP results in mTOR pathway activation, and accelerated depletion of ovarian follicular reserve. 相似文献
926.
Repression of microRNA‐382 inhibits glomerular mesangial cell proliferation and extracellular matrix accumulation via FoxO1 in mice with diabetic nephropathy 下载免费PDF全文
927.
IL‐35 recombinant protein reverses inflammatory bowel disease and psoriasis through regulation of inflammatory cytokines and immune cells 下载免费PDF全文
Yuan Wang Ying Mao Junfeng Zhang Gang Shi Lin Cheng Yi Lin Yiming Li Xiaomei Zhang Yujing Zhang Xiaolei Chen Jie Deng Xiaolan Su Lei Dai Yang Yang Shuang Zhang Dechao Yu Yuquan Wei Hongxin Deng 《Journal of cellular and molecular medicine》2018,22(2):1014-1025
Interleukin‐35 (IL‐35), a member of the IL‐12 family, functions as a new anti‐inflammatory factor involved in arthritis, psoriasis, inflammatory bowel disease (IBD) and other immune diseases. Although IL‐35 can significantly prevent the development of inflammation in many diseases, there have been no early studies accounting for the role of IL‐35 recombinant protein in IBD and psoriasis. In this study, we assessed the therapeutic potential of IL‐35 recombinant protein in three well‐known mouse models: the dextransulfate sodium (DSS)‐induced colitis mouse model, the keratin14 (K14)‐vascular endothelial growth factor A (VEGF‐A)‐transgenic (Tg) psoriasis mouse model and the imiquimod (IMQ)‐induced psoriasis mouse model. Our results indicated that IL‐35 recombinant protein can slow down the pathologic process in DSS‐induced acute colitis mouse model by decreasing the infiltrations of macrophages, CD4+T and CD8+T cells and by promoting the infiltration of Treg cells. Further analysis demonstrated that IL‐35 recombinant protein may regulate inflammation through promoting the secretion of IL‐10 and inhibiting the expression of pro‐inflammatory cytokines such as IL‐6, TNF‐α and IL‐17 in acute colitis model. In addition, lower dose of IL‐35 recombinant protein could achieve long‐term treatment effects as TNF‐α monoclonal antibody did in the psoriasis mouse. In summary, the remarkable therapeutic effects of IL‐35 recombinant protein in acute colitis and psoriasis mouse models indicated that IL‐35 recombinant protein had a variety of anti‐inflammatory effects and was expected to become an effective candidate drug for the treatment of inflammatory diseases. 相似文献
928.
929.
Tianyu Yu Bin Liu Zhigang He Muqing Yang Jian Song Cheng Ma Sunqiang Ma Junlan Feng Xiaodong Wang Jiyu Li 《In vitro cellular & developmental biology. Animal》2018,54(10):705-714
Mast cells (MCs) are responsible for the innate immune response. Rat MCs are more suitable than mouse MCs as models of specific parasite infection processes and ovalbumin-induced asthma. Rat peritoneum-derived MCs and RBL-2H3 cells (an MC cell line) are widely used in disease studies. However, the application of rat bone marrow-derived MCs (BMMCs) are poorly documented in terms of the methodology of rat BMMC isolation. Here, we describe a relatively rapid, efficient, and simple method for the cultivation of rat BMMCs. As compared to previous protocols, rat BMMCs produced with the proposed protocol exhibited advantages in differentiation, proliferation, lifespan, and functionality, which should prove useful for studies of mucosal MC diseases in specific rat models. 相似文献
930.
Genome-wide association study identified genetic variations and candidate genes for plant architecture component traits in Chinese upland cotton 总被引:1,自引:0,他引:1
Junji Su Libei Li Chi Zhang Caixiang Wang Lijiao Gu Hantao Wang Hengling Wei Qibao Liu Long Huang Shuxun Yu 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(6):1299-1314