全文获取类型
收费全文 | 22209篇 |
免费 | 1783篇 |
国内免费 | 1922篇 |
出版年
2024年 | 37篇 |
2023年 | 289篇 |
2022年 | 687篇 |
2021年 | 1210篇 |
2020年 | 804篇 |
2019年 | 1050篇 |
2018年 | 975篇 |
2017年 | 666篇 |
2016年 | 973篇 |
2015年 | 1437篇 |
2014年 | 1617篇 |
2013年 | 1726篇 |
2012年 | 2058篇 |
2011年 | 1822篇 |
2010年 | 1047篇 |
2009年 | 980篇 |
2008年 | 1150篇 |
2007年 | 974篇 |
2006年 | 908篇 |
2005年 | 706篇 |
2004年 | 552篇 |
2003年 | 484篇 |
2002年 | 400篇 |
2001年 | 343篇 |
2000年 | 339篇 |
1999年 | 346篇 |
1998年 | 221篇 |
1997年 | 251篇 |
1996年 | 199篇 |
1995年 | 201篇 |
1994年 | 175篇 |
1993年 | 137篇 |
1992年 | 188篇 |
1991年 | 144篇 |
1990年 | 150篇 |
1989年 | 101篇 |
1988年 | 90篇 |
1987年 | 88篇 |
1986年 | 63篇 |
1985年 | 65篇 |
1984年 | 43篇 |
1983年 | 47篇 |
1982年 | 21篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1969年 | 9篇 |
1968年 | 8篇 |
1965年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
961.
Ming‐Jian Zhang Xiaobing Hu Maofan Li Yandong Duan Luyi Yang Chong Yin Mingyuan Ge Xianghui Xiao Wah‐Keat Lee Jun Young Peter Ko Khalil Amine Zonghai Chen Yimei Zhu Eric Dooryhee Jianming Bai Feng Pan Feng Wang 《Liver Transplantation》2019,9(43)
Transition metal layered oxides have been the dominant cathodes in lithium‐ion batteries, and among them, high‐Ni ones (LiNixMnyCozO2; x ≥ 0.7) with greatly boosted capacity and reduced cost are of particular interest for large‐scale applications. The high Ni loading, on the other hand, raises the critical issues of surface instability and poor rate performance. The rational design of synthesis leading to layered LiNi0.7Mn0.15Co0.15O2 with greatly enhanced rate capability is demonstrated, by implementing a quenching process alternative to the general slow cooling. In situ synchrotron X‐ray diffraction, coupled with surface analysis, is applied to studies of the synthesis process, revealing cooling‐induced surface reconstruction involving Li2CO3 accumulation, formation of a Li‐deficient layer and Ni reduction at the particle surface. The reconstruction process occurs predominantly at high temperatures (above 350 °C) and is highly cooling‐rate dependent, implying that surface reconstruction can be suppressed through synthetic control, i.e., quenching to improve the surface stability and rate performance of the synthesized materials. These findings may provide guidance to rational synthesis of high‐Ni cathode materials. 相似文献
962.
Yanting Hu Ping Zhao Yuqing Huang Liwei Zhu Guangyan Ni Xiuhua Zhao Zhihong Huang 《Journal of Plant Ecology》2019,12(6):982
Aims
Land cover changes can disrupt water balance and alter the partitioning of precipitation into surface runoff, evapotranspiration and groundwater recharge. The widely plantedEucalyptustrees in south-western China have the potential to bring about hydrologic impacts. Our research aims to elucidate the hydrologic balance characteristics of the introduced exoticEucalyptus grandis×Eucalyptus urophyllaplantation and to assess whether its high productivity results from high water use efficiency (WUE) or large water consumption. 相似文献
963.
Guangyi Fan Yaolei Zhang Xiaochuan Liu Jiahao Wang Zeguo Sun Shuai Sun He Zhang Jianwei Chen Meiqi Lv Kai Han Xiaoxuan Tan Jie Hu Rui Guan Yuanyuan Fu Shanshan Liu Xi Chen Qiwu Xu Yating Qin Longqi Liu Jie Bai Ou Wang Jingbo Tang Haorong Lu Zhouchun Shang Bo Wang Guohai Hu Xia Zhao Yan Zou Ao Chen Meihua Gong Wenwei Zhang Simon M.‐Y. Lee Songhai Li Junnian Liu Zhen Li Yishan Lu Jamal S. M. Sabir Mumdooh J. Sabir Muhummadh Khan Nahid H. Hajrah Ye Yin Karsten Kristiansen Huanming Yang Jian Wang Xun Xu Xin Liu 《Molecular ecology resources》2019,19(4):944-956
Marine mammals are important models for studying convergent evolution and aquatic adaption, and thus reference genomes of marine mammals can provide evolutionary insights. Here, we present the first chromosome‐level marine mammal genome assembly based on the data generated by the BGISEQ‐500 platform, for a stranded female sperm whale (Physeter macrocephalus). Using this reference genome, we performed chromosome evolution analysis of the sperm whale, including constructing ancestral chromosomes, identifying chromosome rearrangement events and comparing with cattle chromosomes, which provides a resource for exploring marine mammal adaptation and speciation. We detected a high proportion of long interspersed nuclear elements and expanded gene families, and contraction of major histocompatibility complex region genes which were specific to sperm whale. Using comparisons with sheep and cattle, we analysed positively selected genes to identify gene pathways that may be related to adaptation to the marine environment. Further, we identified possible convergent evolution in aquatic mammals by testing for positively selected genes across three orders of marine mammals. In addition, we used publicly available resequencing data to confirm a rapid decline in global population size in the Pliocene to Pleistocene transition. This study sheds light on the chromosome evolution and genetic mechanisms underpinning sperm whale adaptations, providing valuable resources for future comparative genomics. 相似文献
964.
Precipitation and seasonality affect grazing impacts on herbage nutritive values in alpine meadows on the Qinghai-Tibet Plateau 总被引:1,自引:0,他引:1
Aims
Grasslands used for animal husbandry are chosen depending on the nutritive values of dominant herbage species. However, the influence of grazing in combination with precipitation and growing season on the nutritive values of dominant species has not been explicated. 相似文献
965.
966.
967.
968.
Ping Yu Wenjing Liu Jinghui Ren Yingying Wang Yao Ning Mingqi Huang Xinyi Hu Lili Wei Min Ji Jin Cai 《Bioorganic & medicinal chemistry letters》2019,29(16):2168-2172
Bromodomain-containing protein 4 (BRD4) is a new therapeutic target for the treatment of diseases including cardiovascular diseases, cancer, inflammation and central nervous system (CNS) disorders. In this study, we introduced the pharmacophore of fibrates to a BRD4 inhibitor, RVX-208, to design dual-active hypolipidemic compounds, and found that some of new analogues showed favorable hypolipidemic activities. Synthetic accessibility towards this class of compounds optimized RVX-208 as well as would supply more thoughts on hypolipidemic drugs. 相似文献
969.
Ling-Pan Lu Jin-Hai Liu Shi-Hong Cen Ya-Ling Jiang Guo-Qiang Hu 《Bioorganic & medicinal chemistry letters》2019,29(4):681-683
Lysine specific demethylase (LSD1) plays a pivotal role in epigenetic modulation of gene expression. Abberrant expression of LSD1 was associated with the progress and oncogenesis of multiple human cancers. Herein, we report the preliminary anti-LSD1 evaluation of the synthetic vanadium (V) complexes. Among them, complex 2 showed a moderate inhibitory effect against LSD1 with IC50 value of 19.0?μM, as well as good selectivity over MAO-A/B. Complex 2 is the first vanadium based LSD1 inhibitor, which provides a novel scaffold for the development of LSD1 inhibitor. 相似文献
970.