全文获取类型
收费全文 | 25614篇 |
免费 | 2636篇 |
国内免费 | 1291篇 |
出版年
2023年 | 330篇 |
2022年 | 383篇 |
2021年 | 1050篇 |
2020年 | 905篇 |
2019年 | 1049篇 |
2018年 | 1001篇 |
2017年 | 759篇 |
2016年 | 1076篇 |
2015年 | 1618篇 |
2014年 | 1890篇 |
2013年 | 1998篇 |
2012年 | 2441篇 |
2011年 | 2096篇 |
2010年 | 1332篇 |
2009年 | 1072篇 |
2008年 | 1450篇 |
2007年 | 1219篇 |
2006年 | 1094篇 |
2005年 | 933篇 |
2004年 | 777篇 |
2003年 | 654篇 |
2002年 | 592篇 |
2001年 | 490篇 |
2000年 | 382篇 |
1999年 | 445篇 |
1998年 | 259篇 |
1997年 | 212篇 |
1996年 | 238篇 |
1995年 | 197篇 |
1994年 | 243篇 |
1993年 | 140篇 |
1992年 | 212篇 |
1991年 | 173篇 |
1990年 | 157篇 |
1989年 | 104篇 |
1988年 | 76篇 |
1987年 | 69篇 |
1986年 | 44篇 |
1985年 | 54篇 |
1984年 | 36篇 |
1983年 | 35篇 |
1982年 | 28篇 |
1981年 | 20篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 15篇 |
1976年 | 16篇 |
1975年 | 15篇 |
1973年 | 17篇 |
1969年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Yu-Chen Yang Xiao-Dong WangKai Huang Lu WangZong-Lai Jiang Ying-Xin Qi 《Journal of biomechanics》2014
Vascular smooth muscle cells (VSMCs) are exposed to mechanical cyclic stretch in vivo, which play important roles in maintenance of vascular homeostasis and regulation of pathological vascular remodeling. Reversible protein phosphorylation is crucial for intracellular signaling transduction. However, the dynamic phosphorylated profile induced by cyclic stretch in VSMCs is still unclear. Using the stable isotope labeling by amino acid in cell culture, VSMCs were labeled and exposed to 10% physiological cyclic stretch in vitro at 1.25 Hz for 0 min, 15 min, 30 min, 1 h and 6 h, respectively. Using TiO2 beads and liquid chromatography tandem mass spectrometry, the temporal phosphoproteomic profiles in response to cyclic stretch were then detected. Bioinformatics analysis including fuzzy c-means clustering, functional classifications, and Ingenuity Pathway Analysis were applied to further reveal the potential mechanotranduction networks. The results indicated that protein kinase C (PKCs) family, Rho-associated coiled-coil containing protein kinase 1 (ROCK1) and Akt may participate in cyclic-stretch induced VSMC functions. Cyclic stretch repressed the expression of ROCK1, while it had no significant effect on the phosphorylation of PKCα/βII, PKCζ/λ and PKCδ/θ. PKCθ was activated first at short time-phase (15 min and 30 min), and again at long time-phase (6 h, 12 h and 24 h). The activation of p-PKCμ was immediate and short-term, similar to p-Akt. Our present in vitro work hence revealed that cyclic stretch activates complex mechanotransduction networks, suggesting that novel mechanoresponsive molecules, i.e., PKCθ, PKCμ, and ROCK1, may participate in the mechanotransduction and modulation VSMC functions. 相似文献
3.
正The genetic information of a human being is encoded in the genomic DNA of about 3 billion base pairs.Every new individual starts from a one-cell zygote,or called fertilized egg,carrying genetic and epigenetic information from the parents.The developmental process from one single cell to a whole organism depends on the differential regulation of the genetic information encoded 相似文献
4.
Lu Qiao Yajun Yang Pengcheng Fu Sile Hu Hang Zhou Shouneng Peng Jingze Tan Yan Lu Haiyi Lou Dongsheng Lu Sijie Wu Jing Guo Li Jin Yaqun Guan Sijia Wang Shuhua Xu Kun Tang 《遗传学报》2018,45(8):419-432
It is a long-standing question as to which genes define the characteristic facial features among different ethnic groups. In this study, we use Uyghurs, an ancient admixed population to query the genetic bases why Europeans and Han Chinese look different. Facial traits were analyzed based on high-dense 3D facial images; numerous biometric spaces were examined for divergent facial features between European and Han Chinese, ranging from inter-landmark distances to dense shape geometrics. Genome-wide association studies(GWAS) were conducted on a discovery panel of Uyghurs. Six significant loci were identified, four of which, rs1868752, rs118078182, rs60159418 at or near UBASH3B, COL23A1, PCDH7 and rs17868256 were replicated in independent cohorts of Uyghurs or Southern Han Chinese. A prospective model was also developed to predict 3D faces based on top GWAS signals and tested in hypothetic forensic scenarios. 相似文献
5.
6.
群体成员大小差异对不同生境鲤科鱼类集群行为的影响 总被引:1,自引:0,他引:1
为研究群体成员大小差异对不同喜好生境鱼类集群行为特征的影响, 实验分别以鳊(Parabramis pekinensis)和中华倒刺鲃(Spinibarbus sinensis)幼鱼为实验对象, 比较分析4尾等大小(E)和不等大小(2大2小, NE)实验鱼群体的自发游泳速度、空间分布以及对恐吓刺激反应等集群行为参数的差异。结果显示: (1)和鳊相比, 中华倒刺鲃有更高的自发游泳速度、速度同步性和排列方向的极性, 但二者对恐吓刺激的反应率及反应的协调一致性相似; (2)当群体成员大小出现差异时, 两种鱼群体排列方向的极性不受影响, 且大小个体成员间的速度及其同步性均没有差异, 但整体的速度同步性与等大小群体相比有所下降; (3)个体间距离数据显示, 个体大小差异不会影响两种鱼群体的凝聚力; (4)群体成员在两种鱼群中偏好位置不同, 当群体成员大小不同时, 大个体成员更偏好占据领头鱼位置; (5)群体成员大小的差异导致两种鱼对刺激的反应率下降。研究表明: 中华倒刺鲃具有更高的活跃性、更好的群体运动的协调性, 可能与其流水生境相关; 当群体成员大小出现差异时, 成员不分大小在整体上协调运动的速度和方向, 并保持群体有较高的凝聚力, 但两种鱼类自发游泳速度调整策略截然不同(鳊大小个体速度妥协趋同, 而中华倒刺鲃低速个体速度提高); 群体成员大小差异导致鱼群对恐吓刺激的反应率有所下降, 可能原因包括体形差异导致的社会因素造成敏锐性下降、信息交流效率受阻和(或)集群收益代价出现分化影响一致决策的形成等。 相似文献
7.
NKG2D ligand RAE1ε induces generation and enhances the inhibitor function of myeloid‐derived suppressor cells in mice 下载免费PDF全文
Li Qian Weijuan Gong Xiaoqin Jia Lu Liu Feng Ye Jingjuan Ding Yuwei Xu Yi Fu Fang Tian 《Journal of cellular and molecular medicine》2017,21(9):2046-2054
Expression of surface NKG2D ligands on tumour cells, which activates nature killer (NK) cells and CD8+ T cells, is crucial in antitumour immunity. Some types of tumours have evolved mechanisms to suppress NKG2D‐mediated immune cell activation, such as tumour‐derived soluble NKG2D ligands or sustained NKG2D ligands produced by tumours down‐regulate the expression of NKG2D on NK cells and CD8+ T cells. Here, we report that surface NKG2D ligand RAE1ε on tumour cells induces CD11b+Gr‐1+ myeloid‐derived suppressor cell (MDSC) via NKG2D in vitro and in vivo. MDSCs induced by RAE1ε display a robust induction of IL‐10 and arginase, and these MDSCs show greater suppressive activity by inhibiting antigen‐non‐specific CD8+ T‐cell proliferation. Consistently, upon adoptive transfer, MDSCs induced by RAE1ε significantly promote CT26 tumour growth in IL‐10‐ and arginase‐dependent manners. RAE1ε moves cytokine balance towards Th2 but not Th1 in vivo. Furthermore, RAE1ε enhances inhibitory function of CT26‐derived MDSCs and promotes IL‐4 rather than IFN‐γ production from CT26‐derived MDSCs through NKG2D in vitro. Our study has demonstrated a novel mechanism for NKG2D ligand+ tumour cells escaping from immunosurveillance by facilitating the proliferation and the inhibitory function of MDSCs. 相似文献
8.
Circulating long non‐coding RNAs NRON and MHRT as novel predictive biomarkers of heart failure 下载免费PDF全文
9.
Wei-Qing Li Hong-Yu Yu Yi-Ming Li Xiang Wang Jin He Hong-Zhu Yan Dao-Hua Yang Xiao-Jun Wu Li-Jun Hou Hui-Min Liu Chun-Yan Xia Yi-Cheng Lu 《Biochemical and biophysical research communications》2014
Previous studies from this laboratory indicated that microRNA-21 (miR-21) contributes to chemoresistance of glioblastoma multiforme (GBM) cells to teniposide, a type II topoisomerase inhibitor. We also showed that LRRFIP1 is a target of miR-21. In this study, we found that higher baseline LRRFIP1 expression in human GBM tissue (n = 60) is associated with better prognosis upon later treatment with teniposide. Experiments in cultured U373MG cells showed enhanced toxicity of teniposide against U373MG cells transfected with a vector that resulted in LRRFIP1 overexpression (vs. cells transfected with control vector). Experiments in nude mice demonstrated better response of LRRFIP1 overexpressing xenografts to teniposide. These findings indicate that high baseline LRRFIP1 expression in GBM is associated with better response to teniposide, and encourage exploring LRRFIP1 as a target for GBM treatment. 相似文献
10.
Hongwei Ma Zhiyong Gao Panfeng Yu Shun Shen Yongmei Liu Bainan Xu 《Biochemical and biophysical research communications》2014
Glioma is a huge threat for human being because it was hard to be completely removed owing to both the infiltrating growth of glioma cells and integrity of blood brain barrier. Thus effectively imaging the glioma cells may pave a way for surgical removing of glioma. In this study, a fluorescent probe, Cy3, was anchored onto the terminal of AS1411, a glioma cell targeting aptamer, and then TGN, a BBB targeting peptide, was conjugated with Cy3-AS1411 through a PEG linker. The production, named AsT, was characterized by gel electrophoresis, 1H NMR and FTIR. In vitro cellular uptake and glioma spheroid uptake demonstrated the AsT could not only be uptaken by both glioma and endothelial cells, but also penetrate through endothelial cell monolayer and uptake by glioma spheroids. In vivo, AsT could effectively target to glioma with high intensity. In conclusion, AsT could be used as an effective glioma imaging probe. 相似文献