全文获取类型
收费全文 | 4659篇 |
免费 | 421篇 |
国内免费 | 288篇 |
出版年
2024年 | 3篇 |
2023年 | 48篇 |
2022年 | 135篇 |
2021年 | 242篇 |
2020年 | 148篇 |
2019年 | 191篇 |
2018年 | 200篇 |
2017年 | 150篇 |
2016年 | 207篇 |
2015年 | 318篇 |
2014年 | 337篇 |
2013年 | 394篇 |
2012年 | 403篇 |
2011年 | 401篇 |
2010年 | 234篇 |
2009年 | 195篇 |
2008年 | 260篇 |
2007年 | 219篇 |
2006年 | 166篇 |
2005年 | 173篇 |
2004年 | 127篇 |
2003年 | 134篇 |
2002年 | 103篇 |
2001年 | 84篇 |
2000年 | 71篇 |
1999年 | 73篇 |
1998年 | 44篇 |
1997年 | 38篇 |
1996年 | 42篇 |
1995年 | 41篇 |
1994年 | 33篇 |
1993年 | 25篇 |
1992年 | 25篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有5368条查询结果,搜索用时 125 毫秒
61.
Food Biophysics - Caffeic acid phenethyl ester (CAPE) has high cytotoxicity against various cancer cells but has low water solubility and poor bioavailability. The objective of this work was to... 相似文献
62.
Jingqian Guan Xizi Jiang Junda Gai Xiaodan Sun Jinming Zhao Ji Li Yizhuo Li Ming Cheng Tengjiao Du Lin Fu Qingchang Li 《Journal of cellular and molecular medicine》2020,24(23):14039
Sirtuin 5 (SIRT5) is a NAD+‐dependent class III protein deacetylase, and its role in prostate cancer has not yet been reported. Therefore, to explore the diagnosis and treatment of prostate cancer, we investigated the effect of SIRT5 on prostate cancer. Sirtuin 5 was assessed by immunohistochemistry in 57 normal and cancerous prostate tissues. We found that the tissue expression levels of SIRT5 in patients with Gleason scores ≥7 were significantly different from those in patients with Gleason scores <7 (P < .05, R > 0). Further, mass spectrometry and pathway screening experiments showed that SIRT5 regulated the activity of the mitogen‐activated protein kinase (MAPK) pathway, which in turn modulated the expression of MMP9 and cyclin D1. Being a substrate of SIRT5, acetyl‐CoA acetyltransferase 1 (ACAT1) was regulated by SIRT5. SIRT5 also regulated MAPK pathway activity through ACAT1. These results revealed that SIRT5 promoted the activity of the MAPK pathway through ACAT1, increasing the ability of prostate cancer cells to proliferate, migrate and invade. Overall, these results indicate that SIRT5 expression is closely associated with prostate cancer progression. Understanding the underlying mechanism may provide new targets and methods for the diagnosis and treatment of the disease. 相似文献
63.
Euphorbia factor L3, a lathyrane diterpenoid extracted from Euphorbia lathyris, was found to display good anti‐inflammatory activity with very low cytotoxicity. To find more potent anti‐inflammatory drugs, two series of Euphorbia factor L3 derivatives with fatty and aromatic acids were designed and synthesized. Among them, lathyrane derivative 5n exhibited most potent inhibition on LPS‐induced NO production in RAW264.7 cells with no obvious cytotoxicity. To determine the key characteristics of Euphorbia factor L3 derivatives that contribute to anti‐inflammatory activity, we conducted a structure‐activity relationship study of these compounds. 相似文献
64.
Yanhui Liu Guohui Zhang Yulong Guan Xiaoliang Zhao Quan Wang Hua Li Jinhong Qi 《Journal of cellular and molecular medicine》2020,24(18):10615-10620
The case‐control study was designed to investigate the genetic effects of interferon‐gamma (IFN‐γ) rs2069727 and rs1861494 polymorphisms on ankylosing spondylitis (AS) susceptibility in a Chinese Han population. Blood samples were collected from 108 AS patients and 110 healthy controls. IFN‐γ polymorphisms were genotyped by polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP). Hardy‐Weinberg equilibrium (HWE) test was performed in control group. Odds ratios (OR) with 95% confidence intervals (95% CI) were calculated using chi‐square test to evaluate the association between AS susceptibility and IFN‐γ polymorphisms, and the results were adjusted by logistic regressive analysis. The frequency of rs2069727 CC genotype was much higher in cases than that in controls, suggested its significant association with increased AS risk (adjusted OR = 5.899, 95% CI = 1.563‐22.261; P = .009). In addition, C allele also showed close association with increased risk of AS (adjusted OR = 2.052, 95% CI = 1.286‐1.704, P = 0 .003). While the genotype and allele frequencies of IFN‐γ rs1861494 polymorphism were not significantly different between patients and controls (P > 0.05 for all), IFN‐γ rs2069727 polymorphism is significantly associated with increased AS risk in a Chinese Han Population. 相似文献
65.
Xixi Wang Jaka Sunarso Qian Lu Ziling Zhou Jie Dai Daqin Guan Wei Zhou Zongping Shao 《Liver Transplantation》2020,10(5)
Constructing highly active electrocatalysts with superior stability at low cost is a must, and vital for the large‐scale application of rechargeable Zn–air batteries. Herein, a series of bifunctional composites with excellent electrochemical activity and durability based on platinum with the perovskite Sr(Co0.8Fe0.2)0.95P0.05O3?δ (SCFP) are synthesized via a facile but effective strategy. The optimal sample Pt‐SCFP/C‐12 exhibits outstanding bifunctional activity for the oxygen reduction reaction and oxygen evolution reaction with a potential difference of 0.73 V. Remarkably, the Zn–air battery based on this catalyst shows an initial discharge and charge potential of 1.25 and 2.02 V at 5 mA cm?2, accompanied by an excellent cycling stability. X‐ray photoelectron spectroscopy, X‐ray absorption near‐edge structure, and extended X‐ray absorption fine structure experiments demonstrate that the superior performance is due to the strong electronic interaction between Pt and SCFP that arises as a result of the rapid electron transfer via the Pt? O? Co bonds as well as the higher concentration of surface oxygen vacancies. Meanwhile, the spillover effect between Pt and SCFP also can increase more active sites via lowering energy barrier and change the rate‐determining step on the catalysts surface. Undoubtedly, this work provides an efficient approach for developing low‐cost and highly active catalysts for wider application of electrochemical energy devices. 相似文献
66.
Shuang Liu Yanjun Guan Yusong Sheng Yue Hu Yaoguang Rong Anyi Mei Hongwei Han 《Liver Transplantation》2020,10(13)
Additives are widely adopted for efficient, stable, and hysteresis‐free perovskite solar cells and play an important role in various breakthroughs of perovskite solar cells (PSCs). Herein the various additives adopted for PSCs are reviewed and their functioning mechanism and influence on device performance is described. The main roles of additives, modulating morphology of perovskite films, stabilizing phase of formamidinium (FA) and cesium (Cs)‐based perovskites, adjusting energy level alignment in PSCs, suppressing nonradiative recombination in perovskites, eliminating hysteresis, enhancing operational stability of PSCs, are summarized. 相似文献
67.
Wang Lixia Zhu Fan Yang Huansheng Li Jianzhong Li Yali Ding Xueqin Xiong Xia Ji Fengjie Zhou Hanlin Yin Yulong 《中国科学:生命科学英文版》2020,63(2):259-268
Epidermal growth factor(EGF) has been shown to improve piglet intestinal morphology and epithelial recovery. In an attempt to further understand the mechanisms behind these improvements, this study tested the hypothesis that dietary EGF may affect intestinal morphology by stimulating the proliferation and differentiation of enterocytes in weaning piglets. In piglets receiving200 μg kg–1 EGF, crypt depth and villus height increased(P0.05). Adding 400 μg kg–1 EGF increased villus height-to-crypt depth ratio(P0.05), but reduced crypt depth(P0.05). Dietary supplementation with 200 μg kg–1 EGF significantly increased the number of Ki67-positive cells(P0.01) and tended to increase the mRNA level of proliferating cell nuclear antigen(P0.10).However, this supplementation decreased the expression level of intestinal fatty acid-binding protein(P0.05). Piglets fed with400 μg kg–1 EGF had an increased mRNA level of intestinal alkaline phosphatase(P0.05). The phosphorylation of m TOR(mammalian target of rapamycin) was observed in the 200 μg kg–1 EGF group. These results suggest that dietary supplementation with a low level of EGF improved piglet intestinal morphology through stimulating the proliferation and differentiation of enterocytes, and the mTOR signaling pathway may partly be involved in this process. 相似文献
68.
虽然二甲双胍广泛用于治疗2型糖尿病,但是其对骨骼的潜在影响知之甚少。因此,本研究评估了二甲双胍对培养的大鼠骨髓间充质干细胞(MSCs)和脂肪细胞两者的分化以及增殖的影响。首先随机组形成对照实验,其中对照组为在不经二甲双胍处理培养基中培养MSCs细胞21 d,而二甲双胍组则在用100μmol/L二甲双胍处理培养基中培养MSCs 21 d。结果表明,二甲双胍增强了大鼠MSCs的成骨细胞分化细胞中ALP的活性,抑制了培养中MSCs脂肪形成分化的过程,但是增强了MSCs细胞的增殖能力。 相似文献
69.
70.
Xiaohui Yang Yu Yang Jian Ling Jiantao Guan Xiao Guo Daofeng Dong Liping Jin Sanwen Huang Jun Liu Guangcun Li 《Plant biotechnology journal》2020,18(2):364-372
Traditional approaches for sequencing insertion ends of bacterial artificial chromosome (BAC) libraries are laborious and expensive, which are currently some of the bottlenecks limiting a better understanding of the genomic features of auto‐ or allopolyploid species. Here, we developed a highly efficient and low‐cost BAC end analysis protocol, named BAC‐anchor, to identify paired‐end reads containing large internal gaps. Our approach mainly focused on the identification of high‐throughput sequencing reads carrying restriction enzyme cutting sites and searching for large internal gaps based on the mapping locations of both ends of the reads. We sequenced and analysed eight libraries containing over 3 200 000 BAC end clones derived from the BAC library of the tetraploid potato cultivar C88 digested with two restriction enzymes, Cla I and Mlu I. About 25% of the BAC end reads carrying cutting sites generated a 60–100 kb internal gap in the potato DM reference genome, which was consistent with the mapping results of Sanger sequencing of the BAC end clones and indicated large differences between autotetraploid and haploid genotypes in potato. A total of 5341 Cla I‐ and 165 Mlu I‐derived unique reads were distributed on different chromosomes of the DM reference genome and could be used to establish a physical map of target regions and assemble the C88 genome. The reads that matched different chromosomes are especially significant for the further assembly of complex polyploid genomes. Our study provides an example of analysing high‐coverage BAC end libraries with low sequencing cost and is a resource for further genome sequencing studies. 相似文献