全文获取类型
收费全文 | 229303篇 |
免费 | 18488篇 |
国内免费 | 9549篇 |
专业分类
电工技术 | 13598篇 |
技术理论 | 9篇 |
综合类 | 14026篇 |
化学工业 | 34274篇 |
金属工艺 | 11653篇 |
机械仪表 | 13051篇 |
建筑科学 | 15698篇 |
矿业工程 | 5971篇 |
能源动力 | 6097篇 |
轻工业 | 14415篇 |
水利工程 | 4555篇 |
石油天然气 | 10637篇 |
武器工业 | 1881篇 |
无线电 | 23435篇 |
一般工业技术 | 24437篇 |
冶金工业 | 30096篇 |
原子能技术 | 2361篇 |
自动化技术 | 31146篇 |
出版年
2024年 | 854篇 |
2023年 | 2998篇 |
2022年 | 5398篇 |
2021年 | 7501篇 |
2020年 | 5675篇 |
2019年 | 4666篇 |
2018年 | 5490篇 |
2017年 | 6640篇 |
2016年 | 6306篇 |
2015年 | 8270篇 |
2014年 | 9799篇 |
2013年 | 11420篇 |
2012年 | 14937篇 |
2011年 | 16072篇 |
2010年 | 13086篇 |
2009年 | 12637篇 |
2008年 | 12184篇 |
2007年 | 11555篇 |
2006年 | 11353篇 |
2005年 | 12431篇 |
2004年 | 9109篇 |
2003年 | 7908篇 |
2002年 | 6685篇 |
2001年 | 5942篇 |
2000年 | 4680篇 |
1999年 | 4798篇 |
1998年 | 9352篇 |
1997年 | 6554篇 |
1996年 | 4989篇 |
1995年 | 3581篇 |
1994年 | 2770篇 |
1993年 | 2307篇 |
1992年 | 1218篇 |
1991年 | 1069篇 |
1990年 | 869篇 |
1989年 | 771篇 |
1988年 | 680篇 |
1987年 | 499篇 |
1986年 | 389篇 |
1985年 | 270篇 |
1984年 | 145篇 |
1983年 | 138篇 |
1982年 | 200篇 |
1981年 | 223篇 |
1980年 | 233篇 |
1979年 | 74篇 |
1978年 | 102篇 |
1977年 | 609篇 |
1976年 | 1319篇 |
1975年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Yan Jing Zhu Rongying Wu Fan Zhao Ziyin Ye Huan Hou Mengying Liu Yong Yin Lichen 《Nano Research》2020,13(10):2706-2715
Nano Research - Insufficient intratumoral penetration greatly hurdles the anticancer performance of nanomedicine. To realize highly efficient tumor penetration in a precisely and spatiotemporally... 相似文献
43.
44.
Wojciech Jó?wicki Anna A. Bro?yna Jerzy Siekiera Andrzej T. Slominski 《International journal of molecular sciences》2015,16(2):3783-3803
RCAS1 is a protein that participates in regulation of the tumor microenvironment and its immune responses, all in order to evade the immune system. The aim of this study was to analyze RCAS1 expression in urothelial bladder cancer cells (and in fibroblasts and macrophages of the tumor stroma) and its relationship with the histological pattern of malignancy. Eighty-three postcystectomy patients were enrolled. We analyzed the histological maturity (grade), progress (pT stage), tissue invasion type (TIT), nonclassic differentiation number (NDN), and the ability to metastasize (pN). The expression of RCAS1 protein was analyzed by immunohistochemistry. Indicators of histological malignancy were observed solely in association with the RCAS1 expression in cells in the border parts (BPs) of the tumor. Histological malignancy of the tumor, indicated by the pT and pN, and metastasis-free survival time, correlated significantly with RCAS1 expression in tumor neoplastic cells, whereas malignancy determined by grade, TIT, and NDN correlated with RCAS1 expression in fibroblasts and macrophages in the tumor microenvironment. These findings suggest that the increased RCAS1 expression depends on its cellular source and that RCAS1 expression itself is a component of various signaling pathways. The immune escape occurs within the tumor BPs, where the increase in the RCAS1 expression occurs within tumor cells and stromal cells in its microenvironment. We conclude that the histological pattern of tumor malignancy, indicated by grade, TIT, NDN, pT, and pN is a morphological indicator of immune escape. 相似文献
45.
46.
47.
Xiaoyan Qiu Yongqiang Zhang Haitao Wu Rui Yang Jun Yang Rongjuan Liu Yong Liu Zhiping Zhou Tongfan Hao Yijing Nie 《Polymer International》2019,68(2):218-224
The crystallization of capped ultrathin polymer films is closely dependent on film thickness and interfacial interaction. Using dynamic Monte Carlo simulations, the crystallization behaviors of polymer films confined between two substrates were investigated. The crystallization rate of confined polymers is reduced with high interfacial interactions. Above a critical strength of interfacial interaction, polymer crystallization in the thin film is inhibited within the simulation time scales. An increase in film thickness leads to a rise in critical interfacial interaction. In thicker films, the chains have more space to change conformation to form crystal stems. In addition, there are fewer absorbed segments in confined chains for the thicker films, and thus the chains have stronger ability to adjust their conformation. Therefore an increase in film thickness can cause a reduction in the entropic barrier required for the formation of crystals and thus an increase in the critical interfacial interaction. © 2018 Society of Chemical Industry 相似文献
48.
A first‐principles‐based effective Hamiltonian is developed and employed to investigate finite‐temperature structural properties of a prototype of perovskite halides, that is CsPbI3. Such simulations, when using first‐principles‐extracted coefficients, successfully reproduce the existence of an orthorhombic Pnma state and its iodine octahedral tilting angles around room temperature. However, they also yield a direct transformation from Pnma to cubic upon heating, unlike measurements that reported the occurrence of an intermediate long‐range‐tilted tetragonal P4/mbm phase in‐between the orthorhombic and cubic phases. Such disagreement, which may cast some doubts about the extent to which first‐principle methods can be trusted to mimic hybrid perovskites, can be resolved by “only” changing one short‐range tilting parameter in the whole set of effective Hamiltonian coefficients. In such a case, some reasonable values of this specific parameter result in the predictions that i) the intermediate P4/mbm state originates from fluctuations over many different tilted states; and ii) the cubic phase is highly locally distorted and develops strong transverse antiphase correlation between first‐nearest neighbor iodine octahedral tiltings, before undergoing a phase transition to P4/mbm under cooling. 相似文献
49.
50.
Thermoresponsive behavior and rheology of SiO2–hyaluronic acid/poly(N‐isopropylacrylamide) (NaHA/PNIPAm) core–shell structured microparticles
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)