全文获取类型
收费全文 | 7379篇 |
免费 | 562篇 |
国内免费 | 538篇 |
出版年
2024年 | 10篇 |
2023年 | 104篇 |
2022年 | 254篇 |
2021年 | 445篇 |
2020年 | 254篇 |
2019年 | 323篇 |
2018年 | 283篇 |
2017年 | 243篇 |
2016年 | 315篇 |
2015年 | 434篇 |
2014年 | 530篇 |
2013年 | 544篇 |
2012年 | 660篇 |
2011年 | 562篇 |
2010年 | 332篇 |
2009年 | 351篇 |
2008年 | 379篇 |
2007年 | 304篇 |
2006年 | 283篇 |
2005年 | 208篇 |
2004年 | 219篇 |
2003年 | 214篇 |
2002年 | 136篇 |
2001年 | 136篇 |
2000年 | 128篇 |
1999年 | 143篇 |
1998年 | 83篇 |
1997年 | 70篇 |
1996年 | 81篇 |
1995年 | 70篇 |
1994年 | 61篇 |
1993年 | 31篇 |
1992年 | 62篇 |
1991年 | 43篇 |
1990年 | 40篇 |
1989年 | 22篇 |
1988年 | 24篇 |
1987年 | 28篇 |
1986年 | 16篇 |
1985年 | 33篇 |
1984年 | 8篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有8479条查询结果,搜索用时 0 毫秒
291.
Cuicui Li Bingsheng Qin Yunfeng Zhang Alberto Varzi Stefano Passerini Jiaying Wang Jiaming Dong Danli Zeng Zhihong Liu Hansong Cheng 《Liver Transplantation》2019,9(10)
Herein, a novel electrospun single‐ion conducting polymer electrolyte (SIPE) composed of nanoscale mixed poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) and lithium poly(4,4′‐diaminodiphenylsulfone, bis(4‐carbonyl benzene sulfonyl)imide) (LiPSI) is reported, which simultaneously overcomes the drawbacks of the polyolefin‐based separator (low porosity and poor electrolyte wettability and thermal dimensional stability) and the LiPF6 salt (poor thermal stability and moisture sensitivity). The electrospun nanofiber membrane (es‐PVPSI) has high porosity and appropriate mechanical strength. The fully aromatic polyamide backbone enables high thermal dimensional stability of es‐PVPSI membrane even at 300 °C, while the high polarity and high porosity ensures fast electrolyte wetting. Impregnation of the membrane with the ethylene carbonate (EC)/dimethyl carbonate (DMC) (v:v = 1:1) solvent mixture yields a SIPE offering wide electrochemical stability, good ionic conductivity, and high lithium‐ion transference number. Based on the above‐mentioned merits, Li/LiFePO4 cells using such a SIPE exhibit excellent rate capacity and outstanding electrochemical stability for 1000 cycles at least, indicating that such an electrolyte can replace the conventional liquid electrolyte–polyolefin combination in lithium ion batteries (LIBs). In addition, the long‐term stripping–plating cycling test coupled with scanning electron microscope (SEM) images of lithium foil clearly confirms that the es‐PVPSI membrane is capable of suppressing lithium dendrite growth, which is fundamental for its use in high‐energy Li metal batteries. 相似文献
292.
Kang Shen Zeng Wang Xuanxuan Bi Yao Ying Duo Zhang Chengbin Jin Guangya Hou Huazhen Cao Liankui Wu Guoqu Zheng Yiping Tang Xinyong Tao Jun Lu 《Liver Transplantation》2019,9(20)
Lithium metal is the most attractive anode material due to its extremely high specific capacity, minimum potential, and low density. However, uncontrollable growth of lithium dendrite results in severe safety and cycling stability concerns, which hinders the application in next generation secondary batteries. In this paper, a new and facile method imposing a magnetic field to lithium metal anodes is proposed. That is, the lithium ions suffering Lorentz force due to the electromagnetic fields are put into spiral motion causing magnetohydrodynamics (MHD) effect. This MHD effect can effectively promote mass transfer and uniform distribution of lithium ions to suppress the dendrite growth as well as obtain uniform and compact lithium deposition. The results show that the lithium metal electrodes within the magnetic field exhibit excellent cycling and rate performance in a symmetrical battery. Additionally, full batteries using limited lithium metal as anodes and commercial LiFePO4 as cathodes show improved performance within the magnetic field. In summary, a new and facile strategy of suppressing lithium dendrites using the MHD effect by imposing a magnetic field is proposed, which may be generalized to other advanced alkali metal batteries. 相似文献
293.
Hezhe Lin Malin Li Xu Yang Dongxu Yu Yi Zeng Chunzhong Wang Gang Chen Fei Du 《Liver Transplantation》2019,9(20)
Thanks to low costs and the abundance of the resources, sodium‐ion (SIBs) and potassium‐ion batteries (PIBs) have emerged as leading candidates for next‐generation energy storage devices. So far, only few materials can serve as the host for both Na+ and K+ ions. Herein, a cubic phase CuSe with crystal‐pillar‐like morphology (CPL‐CuSe) assembled by the nanosheets are synthesized and its dual functionality in SIBs and PIBs is comprehensively studied. The electrochemical measurements demonstrate that CPL‐CuSe enables fast Na+ and K+ storage as well as the sufficiently long duration. Specifically, the anode delivers a specific capacity of 295 mA h g?1 at current density of 10 A g?1 in SIBs, while 280 mA h g?1 at 5 A g?1 in PIBs, as well as the high capacity retention of nearly 100% over 1200 cycles and 340 cycles, respectively. Remarkably, CPL‐CuSe exhibits a high initial coulombic efficiency of 91.0% (SIBs) and 92.4% (PIBs), superior to most existing selenide anodes. A combination of in situ X‐ray diffraction and ex situ transmission electron microscopy tests fundamentally reveal the structural transition and phase evolution of CuSe, which shows a reversible conversion reaction for both cells, while the intermediate products are different due to the sluggish K+ insertion reaction. 相似文献
294.
Franziska Enzmann Markus Stckl An‐Ping Zeng Dirk Holtmann 《Engineering in Life Science》2019,19(2):121-132
Facing energy problems, there is a strong demand for new technologies dealing with the replacement of fossil fuels. The emerging fields of biotechnology, photobiotechnology and electrobiotechnology, offer solutions for the production of fuels, energy, or chemicals using renewable energy sources (light or electrical current e.g. produced by wind or solar power) or organic (waste) substrates. From an engineering point of view both technologies have analogies and some similar challenges, since both light and electron transfer are primarily surface‐dependent. In contrast to that, bioproduction processes are typically volume dependent. To allow large scale and industrially relevant applications of photobiotechnology and electrobiotechnology, this opinion first gives an overview over the current scales reached in these areas. We then try to point out the challenges and possible methods for the scale up or numbering up of the reactors used. It is shown that the field of photobiotechnology is by now much more advanced than electrobiotechnology and has achieved industrial applications in some cases. We argue that transferring knowledge from photobiotechnology to electrobiotechnology can speed up the development of the emerging field of electrobiotechnology. We believe that a combination of scale up and numbering up, as it has been shown for several photobiotechnological reactors, may well lead to industrially relevant scales in electrobiotechnological processes allowing an industrial application of the technology in near future. 相似文献
295.
Jiarui Li Pengcheng Du Adam Yongxin Ye Yuanyuan Zhang Chuan Song Hui Zeng Chen Chen 《基因组蛋白质组与生物信息学报(英文版)》2019,17(1):106-117
Identifying antimicrobial resistant(AMR) bacteria in metagenomics samples is essential for public health and food safety. Next-generation sequencing(NGS) technology has provided a powerful tool in identifying the genetic variation and constructing the correlations between genotype and phenotype in humans and other species. However, for complex bacterial samples, there lacks a powerful bioinformatic tool to identify genetic polymorphisms or copy number variations(CNVs) for given genes. Here we provide a Bayesian framework for genotype estimation for mixtures of multiple bacteria, named as Genetic Polymorphisms Assignments(GPA). Simulation results showed that GPA has reduced the false discovery rate(FDR) and mean absolute error(MAE) in CNV and single nucleotide variant(SNV) identification. This framework was validated by whole-genome sequencing and Pool-seq data from Klebsiella pneumoniae with multiple bacteria mixture models, and showed the high accuracy in the allele fraction detections of CNVs and SNVs in AMR genes between two populations. The quantitative study on the changes of AMR genes fraction between two samples showed a good consistency with the AMR pattern observed in the individual strains. Also, the framework together with the genome annotation and population comparison tools has been integrated into an application, which could provide a complete solution for AMR gene identification and quantification in unculturable clinical samples. The GPA package is available at https://github.com/IID-DTH/GPA-package. 相似文献
296.
297.
298.
299.
Hong-yuan Zeng Lin-han Chen Yang Yang Xiao Deng Xi-hong Zhou 《Soil & Sediment Contamination》2019,28(1):1-14
In the present study, field micro-plot experiments were conducted to investigate the basal and foliar application of a tested organic fertilizer amendment (OFA) for decreasing the risk of Cd accumulating in rice. The results showed that applications of OFA significantly increased rice yields in Cd-polluted soil and reduced the level of Cd in rice plants, especially in rice grain. In addition, three application methods of OFA were investigated (single basal application (B1, B2, and B3), combined basal application (+LM, +D, and +Z), and foliar application (F1, F2)). Treat B, F, +LM, +D were all higher than control on rice yield with 25.03, 28.05, 30.61, 22.50 g pot?1 on average, respectively. Among which, rice cadmium depress to 0.33 mg kg?1 in foliar application is considered to be a more efficient and economical method of heavy metal remediation. The mechanism of foliar application to alleviate the accumulation of Cd in brown rice may be related to the probable Cd sequestration in the leaves and straws. And the doses of the foliar application were 2.25–3.75 kg hm?2, approximately 1.0–2.5% of the basal application amount yet with more effect (0.10 mg kg?1 more than single basal; 0.23 mg kg?1 more than combined basal) on Cd reduction. 相似文献
300.