全文获取类型
收费全文 | 35590篇 |
免费 | 3200篇 |
国内免费 | 1574篇 |
专业分类
电工技术 | 2152篇 |
技术理论 | 6篇 |
综合类 | 2830篇 |
化学工业 | 5853篇 |
金属工艺 | 1784篇 |
机械仪表 | 2059篇 |
建筑科学 | 2860篇 |
矿业工程 | 839篇 |
能源动力 | 973篇 |
轻工业 | 3860篇 |
水利工程 | 738篇 |
石油天然气 | 1604篇 |
武器工业 | 326篇 |
无线电 | 4007篇 |
一般工业技术 | 3871篇 |
冶金工业 | 1347篇 |
原子能技术 | 452篇 |
自动化技术 | 4803篇 |
出版年
2025年 | 8篇 |
2024年 | 539篇 |
2023年 | 644篇 |
2022年 | 1004篇 |
2021年 | 1407篇 |
2020年 | 1147篇 |
2019年 | 948篇 |
2018年 | 1001篇 |
2017年 | 1091篇 |
2016年 | 1041篇 |
2015年 | 1417篇 |
2014年 | 1748篇 |
2013年 | 2189篇 |
2012年 | 2454篇 |
2011年 | 2692篇 |
2010年 | 2349篇 |
2009年 | 2286篇 |
2008年 | 2316篇 |
2007年 | 2115篇 |
2006年 | 2002篇 |
2005年 | 1744篇 |
2004年 | 1193篇 |
2003年 | 930篇 |
2002年 | 876篇 |
2001年 | 741篇 |
2000年 | 696篇 |
1999年 | 735篇 |
1998年 | 568篇 |
1997年 | 474篇 |
1996年 | 418篇 |
1995年 | 382篇 |
1994年 | 271篇 |
1993年 | 215篇 |
1992年 | 173篇 |
1991年 | 120篇 |
1990年 | 89篇 |
1989年 | 82篇 |
1988年 | 69篇 |
1987年 | 34篇 |
1986年 | 42篇 |
1985年 | 20篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 8篇 |
1976年 | 6篇 |
1973年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
为探明不同加工工艺对临安山核桃营养成分的影响,运用高效液相色谱、气相色谱法分析其营养成分含量。结果表明,不同加工工艺对山核桃粗蛋白含量影响差异不显著;烘煮工艺、干炒工艺熟制山核桃氨基酸总量较生核桃分别下降14.86%和25.95%。其中人体必需氨基酸总量较生核桃分别下降19.69%和29.96%。干炒工艺较烘煮工艺熟制山核桃氨基酸总量下降13.02%,人体必需氨基酸下降12.79%;烘煮工艺、干炒工艺熟制山核桃分别较生山核桃不饱和脂肪酸含量下降6.43%和18.18%,饱和脂肪酸含量上升40.61%和114.70%。 相似文献
42.
43.
乳酸杆菌是肠道益生菌,主要通过其表面的黏附因子定殖于肠道而发挥益生作用。为了研究乳酸杆菌表面性质与黏附能力之间的关系,选择五种乳酸杆菌,分别进行自聚集能力、表面疏水性及与致病菌大肠杆菌ATCC25922和枯草芽孢杆菌K的共聚能力测定。同时,利用氯化锂和高碘酸钠分别处理乳酸杆菌后再与致病菌进行共聚作用,研究乳酸杆菌表面参与黏附的活性物质。结果表明,约氏乳酸杆菌F0421和副干酪乳酸杆菌M5-L具有良好的表面性质和黏附特性。乳酸杆菌与枯草芽孢杆菌K的共聚作用较好。同时,氯化锂和高碘酸钠处理前后,乳酸杆菌对致病菌的聚集能力有所下降,表明菌株表面蛋白及多糖参与了黏附过程。 相似文献
44.
Yu Zhang Manqi Zhang Amin Yao Yalin Xie Jingxiong Lin Farooqi Sharifullah Yixin Hong Hongbo Chen Fang Cheng Wei Lai 《International journal of molecular sciences》2022,23(23)
Photoaging is not only the main cause of skin aging caused by exogenous factors, it is also related to a variety of skin diseases and even malignant tumors. Excessive and repeated exposure to ultraviolet radiation, especially UVA induces oxidative stress, DNA damage, inflammation, and collagen and elastin degeneration, ultimately leads to skin photoaging, manifested by skin redness, coarse wrinkles, and pigmentation even skin cancer. There has been a large demand of effective prevention and medications but approaches in the current management of photoaging are very limited. In the previous study, we found that a non-coding circular RNA circ_0011129 acts as a miR-6732-5p adsorption sponge to inhibit the reduction of type I collagen and the denaturation and accumulation of elastin in UVA-induced HDF cells photoaging model. However, in vivo instability and efficient delivery to the target cell of circRNA is a major challenge for its clinical application. Therefore, improving its stability and delivery efficiency are desired. In this study, we proposed a strategy of delivering circ_0011129 with small extracellular vesicles (sEVs) from human adipose-derived stem cells (hADSCs) to intervene in the photoaging process. The results showed that sEVs from hADSCs in 3D bioreactor culture (3D-sEVs) can prevent photoaging. Consequently, by overexpressing circ_0011129 in hADSCs, we successfully loaded it into 3D-sEVs (3D-circ-sEVs) and its protective effect was better. Our studies provide a novel approach to preventing skin photoaging, which has important clinical significance and application value for the development of non-coding RNA drugs to treat skin photoaging. We first screened out hADSCs-derived sEVs with excellent anti-oxidant effects. We then compared the sEVs collected from traditional 2D culture with 3D bioreactor culture. By miRNA-seq and GEO data analysis, we found that miRNAs in 3D-sEVs were enriched in cell activities related to apoptosis, cellular senescence, and inflammation. Subsequently, we prepared circ_0011129-loaded 3D-sEVs (3D-circ-sEVs) by overexpressing it in hADSCs for the treatment of photoaging in vitro. We proved that 3D-circ-sEVs can interfere with the process of cell photoaging and protect cells from UVA radiation damage, as well as in a H2O2-induced oxidative stress model. 相似文献
45.
Mingyu Fang Xing Wang Zhikun Jia Qiongju Qiu Peng Li Li Chen Hui Yang 《International journal of molecular sciences》2022,23(23)
Amino acid decarboxylases convert amino acids into different biogenic amines which regulate diverse biological processes. Therefore, identifying the substrates of amino acid decarboxylases is critical for investigating the function of the decarboxylases, especially for the new genes predicted to be amino acid decarboxylases. In the present work, we have established a simple and efficient method to identify the substrates and enzymatic activity of amino acid decarboxylases based on LC-MS methods. We chose GAD65 and AADC as models to validate our method. GAD65 and AADC were expressed in HEK 293T cells and purified through immunoprecipitation. The purified amino acid decarboxylases were subjected to enzymatic reaction with different substrate mixtures in vitro. LC-MS analysis of the reaction mixture identified depleted or accumulated metabolites, which corresponded to candidate enzyme substrates and products, respectively. Our method successfully identified the substrates and products of known amino acid decarboxylases. In summary, our method can efficiently identify the substrates and products of amino acid decarboxylases, which will facilitate future amino acid decarboxylase studies. 相似文献
46.
SARS-CoV-2 as a zoonotic virus has significantly affected daily life and social behavior since its outbreak in late 2019. The concerns over its transmission through different media directly or indirectly have evoked great attention about the survival of SARS-CoV-2 virions in the environment and its potential infection of other animals. To evaluate the risk of infection by SARS-CoV-2 and to counteract the COVID-19 disease, extensive studies have been performed to understand SARS-CoV-2 biogenesis and its pathogenesis. This review mainly focuses on the molecular architecture of SARS-CoV-2, its potential for infecting marine animals, and the prospect of drug discovery using marine natural products to combat SARS-CoV-2. The main purposes of this review are to piece together progress in SARS-CoV-2 functional genomic studies and antiviral drug development, and to raise our awareness of marine animal safety on exposure to SARS-CoV-2. 相似文献
47.
Peizhou Xu Tingkai Wu Asif Ali Jinhao Wang Yongqiong Fang Runrun Qiang Yutong Liu Yunfeng Tian Su Liu Hongyu Zhang Yongxiang Liao Xiaoqiong Chen Farwa Shoaib Changhui Sun Zhengjun Xu Duo Xia Hao Zhou Xianjun Wu 《International journal of molecular sciences》2022,23(18)
Salicylic acid (SA) is a stress hormone synthesized in phenylalanine ammonia-lyase (PAL) and the branching acid pathway. SA has two interconvertible forms in plants: SAG (SA O-β-glucoside) and SA (free form). The molecular mechanism of conversion of SA to SAG had been reported previously. However, which genes regulate SAG to SA remained unknown. Here, we report a cytoplasmic β-glucosidase (β-Glu) which participates in the SA pathway and is involved in the brown hull pigmentation in rice grain. In the current study, an EMS-generated mutant brown hull 1 (bh1) displayed decreased contents of SA in hulls, a lower photosynthesis rate, and high-temperature sensitivity compared to the wild type (WT). A plaque-like phenotype (brown pigmentation) was present on the hulls of bh1, which causes a significant decrease in the seed setting rate. Genetic analysis revealed a mutation in LOC_Os01g67220, which encodes a cytoplasmic Os1βGlu4. The knock-out lines displayed the phenotype of brown pigmentation on hulls and decreased seed setting rate comparable with bh1. Overexpression and complementation lines of Os1βGlu4 restored the phenotype of hulls and normal seed setting rate comparable with WT. Subcellular localization revealed that the protein of Os1βGlu4 was localized in the cytoplasm. In contrast to WT, bh1 could not hydrolyze SAG into SA in vivo. Together, our results revealed the novel role of Os1βGlu4 in the accumulation of flavonoids in hulls by regulating the level of free SA in the cellular pool. 相似文献
48.
49.
Yu-Heng Mao Feng-Lin Song Yi-Xuan Xu Ang-Xin Song Zhao-Mei Wang Ming-Zhu Zhao Fang He Ze-Zhong Tian Yan Yang 《International journal of molecular sciences》2022,23(20)
Cardiovascular diseases are associated with platelet hyperactivity, and downregulating platelet activation is one of the promising antithrombotic strategies. This study newly extracted two polysaccharides (purified exopolysaccharides, EPSp and purified intercellular exopolysaccharides, IPSp) from Cordyceps sinensis Cs-4 mycelial fermentation powder, and investigated the effects of the two polysaccharides and their gut bacterial metabolites on platelet functions and thrombus formation. EPSp and IPSp are majorly composed of galactose, mannose, glucose, and arabinose. Both EPSp and IPSp mainly contain 4-Galp and 4-Glcp glycosidic linkages. EPSp and IPSp significantly inhibited human platelet activation and aggregation with a dose-dependent manner, and attenuated thrombus formation in mice without increasing bleeding risk. Furthermore, the EPSp and IPSp after fecal fermentation showed enhanced platelet inhibitory effects. The results have demonstrated the potential value of Cs-4 polysaccharides as novel protective ingredients for cardiovascular diseases. 相似文献
50.
Zhengyu Fang Yiping Hu Jiajing Dai Lianhua He Juan He Bihua Xu Xinle Han Fubo Zhong Huiyao Lan Qingwen Wang 《International journal of molecular sciences》2022,23(21)
Rheumatoid arthritis (RA) is a common disease worldwide and is treated commonly with methotrexate (MTX). CS12192 is a novel JAK3 inhibitor discovered by Chipscreen Biosciences for the treatment of autoimmune diseases. In the present study, we examined the therapeutic effect of CS12192 against RA and explored if the combinational therapy of CS12192 and MTX produced a synergistic effect against RA in rat collagen-induced arthritis (CIA). Arthritis was induced in male Sprague-Dawley rats by two intradermal injections of bovine type II collagen (CII) and treated with MTX, CS12192, or the combination of CS12192 and MTX daily for two weeks. Effects of different treatments on arthritis score, X-ray score, pathology, and expression of inflammatory cytokines and biomarkers were examined. We found that treatment with either CS12192 or MTX produced a comparable therapeutic effect on CIA including: (1) significantly lowering the arthritis score, X-ray score, serum levels of rheumatic factor (RF), C-reactive protein (CRP), and anti-nuclear antibodies (ANA); (2) largely alleviating histopathological damage, reducing infiltration of Th17 cells while promoting Treg cells; (3) inhibiting the expression of inflammatory cytokines and chemokines such as IL-1β, TNF-α, IL-6, CCL2, and CXCL1. All these inhibitory effects were further improved by the combinational therapy with MTX and CS12192. Of importance, the combinational treatment also resulted in a marked switching of the Th17 to Treg and the M1 to M2 immune responses in synovial tissues of CIA. Thus, when compared to the monotherapy, the combination treatment with CS12192 and MTX produces a better therapeutic effect against CIA with a greater suppressive effect on T cells and macrophage-mediated joint inflammation. 相似文献