全文获取类型
收费全文 | 21794篇 |
免费 | 2072篇 |
国内免费 | 3560篇 |
出版年
2024年 | 75篇 |
2023年 | 364篇 |
2022年 | 844篇 |
2021年 | 1338篇 |
2020年 | 1088篇 |
2019年 | 1252篇 |
2018年 | 1045篇 |
2017年 | 803篇 |
2016年 | 1059篇 |
2015年 | 1583篇 |
2014年 | 1834篇 |
2013年 | 1885篇 |
2012年 | 2360篇 |
2011年 | 2068篇 |
2010年 | 1297篇 |
2009年 | 1217篇 |
2008年 | 1281篇 |
2007年 | 1042篇 |
2006年 | 905篇 |
2005年 | 768篇 |
2004年 | 631篇 |
2003年 | 575篇 |
2002年 | 436篇 |
2001年 | 302篇 |
2000年 | 247篇 |
1999年 | 219篇 |
1998年 | 124篇 |
1997年 | 97篇 |
1996年 | 98篇 |
1995年 | 94篇 |
1994年 | 66篇 |
1993年 | 49篇 |
1992年 | 59篇 |
1991年 | 52篇 |
1990年 | 39篇 |
1989年 | 35篇 |
1988年 | 19篇 |
1987年 | 20篇 |
1986年 | 9篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 20篇 |
1982年 | 15篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1973年 | 6篇 |
1972年 | 11篇 |
1971年 | 7篇 |
1970年 | 7篇 |
1968年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
161.
Shi-Liang Zhou Xin-Hui Zou Zhi-Qin Zhou Jing Liu Chao Xu Jing Yu Qiang Wang Da-Ming Zhang Xiao-Quan Wang Song Ge Tao Sang Kai-Yu Pan De-Yuan Hong 《Proceedings. Biological sciences / The Royal Society》2014,281(1797)
The origin of cultivated tree peonies, known as the ‘king of flowers'' in China for more than 1000 years, has attracted considerable interest, but remained unsolved. Here, we conducted phylogenetic analyses of explicitly sampled traditional cultivars of tree peonies and all wild species from the shrubby section Moutan of the genus Paeonia based on sequences of 14 fast-evolved chloroplast regions and 25 presumably single-copy nuclear markers identified from RNA-seq data. The phylogeny of the wild species inferred from the nuclear markers was fully resolved and largely congruent with morphology and classification. The incongruence between the nuclear and chloroplast trees suggested that there had been gene flow between the wild species. The comparison of nuclear and chloroplast phylogenies including cultivars showed that the cultivated tree peonies originated from homoploid hybridization among five wild species. Since the origin, thousands of cultivated varieties have spread worldwide, whereas four parental species are currently endangered or on the verge of extinction. The documentation of extensive homoploid hybridization involved in tree peony domestication provides new insights into the mechanisms underlying the origins of garden ornamentals and the way of preserving natural genetic resources through domestication. 相似文献
162.
Wenli Xie Ling Wei Jing Guo Hui Guo Xianrang Song Xiugui Sheng 《Journal of cellular biochemistry》2019,120(7):10884-10892
The Wilms’ tumor-associated gene WT1 encodes a tumor suppressor gene, which is implicated in renal differentiation and development of adult urogenital system. Wilms’ tumor 1-associating protein (WTAP) is initially identified as a nuclear protein that specifically interacts with WT1 in both in vitro and in vivo assays. WTAP is ubiquitously expressed in different tissues and various growth periods, and its expression is involved in cell cycle, RNA splicing and stabilization, N6-methyladenosine RNA modification, cell proliferation, and apoptosis as well as embryonic development. In the present review, we aimed to summarize the functions of WTAP in various physiological and pathological processes, in particular with regard to the current knowledge about the role of WTAP in tumorigenesis of different cancers. 相似文献
163.
基于InVEST模型的疏勒河流域碳储量时空变化研究 总被引:9,自引:0,他引:9
研究区域土地利用方式与生态系统服务碳储量的关系,对于区域生态系统保护及经济社会可持续发展具有重要意义。利用InVEST模型碳储量模块和CA-Markov模型,探究并预测疏勒河流域1990-2015及2015-2040年流域生态系统碳储量时空变化特征及其与土地利用方式之间的关系。结果表明:疏勒河流域1990、1995、2000、2005、2010、2015年碳储量分别为7.994×108、7.996×108、7.998×108、8.038×108、8.064×108、8.071×108t,呈逐年增加趋势,累计增加7.7×106t。土地利用类型变化是导致生态系统碳储量变化的主要因素,未利用地向耕地和草地转化有利于碳储量增加,而草地向耕地和未利用地的转化则导致碳储量减少。疏勒河流域碳储量存在显著的空间格局,碳储量较高区域呈现"北部点状-中部带状-南部点状片状"特征,这种分布格局与流域土地利用类型紧密联系。预测表明至2040年疏勒河流域碳储量为9.128×108t,较2015年增加13.1%,主要原因是草地、耕地和林地面积较大幅度增长,提高了流域内的碳储量。 相似文献
164.
165.
166.
I V Ke?lis-Borok 《Tsitologiia》1979,21(9):1065-1073
There are about 2000 (1830 +/- 360) clonogenic precursors of fibroblast (CFU(f)) in the peritoneal liquid of guinea-pig, which form colonies (clones) in the monolayer cultures. The colonies consist of actively proliferating fibroblasts with different morphology. The proportion of colonies with different morphology shows changes during the growth of cultures. During aseptic inflammation the number of CFU(f) in the peritoneal liquid increases by 25, 15 and 4 times after 6 and 24 hours and 3 days, resp., compared to the control. 99% CFU(f) does not proliferate in situ, and the increase of the number of CFU(f) after inflammation is not followed by their proliferation. The irradiation of the peritoneal cavity killed the most of CFU(f)--97-99%. During the aseptic inflammation, the number of CFU(f) increased to 470 +/- 105 during 4 days after the irradiation, which is 5% of the number of CFU(f) on the 3rd day of inflammation for the non-irradiated animals. Thus, no intensive repopulation of clonogenic precursors of fibroblasts occurs in the peritoneal cavity. 相似文献
167.
168.
目的:探讨mi R-5195-3p对人宫颈癌细胞系Si Ha增殖、迁移与侵袭的影响。方法:采用qRT-PCR检测人宫颈癌细胞SiHa和正常上皮细胞HaCaT中mi R-5195-3p的表达水平。将mi R-5195-3p mimic转染至Si Ha细胞中构建外源性过表达细胞株,阴性对照组中则转染NC mimic,并用q RT-PCR验证转染效率;通过MTT和集落形成实验检测细胞增殖能力;划痕愈合实验检测细胞横向迁移能力; Transwell小室实验检测细胞纵向迁移能力和侵袭能力;采用qRT-PCR和Western blot检测E-cadherin、Vimentin与snail m RNA转录水平及蛋白表达水平。结果:宫颈癌细胞Si Ha中的mi R-5195-3p表达水平较HaCaT偏低(P 0. 05)。与阴性对照组相比,转染mi R-5195-3p mimic的SiHa细胞中mi R-5195-3p水平显著增高(P 0. 01);并且其体外增殖(P 0. 001),迁移(P 0. 001)与侵袭能力(P 0. 001)明显减弱;同时E-cadherin表达水平上调而Vimentin、snail表达水平下调。结论:过表达mi R-5195-3p可能通过阻碍EMT通路抑制宫颈癌细胞Si Ha的增殖,迁移与侵袭。 相似文献
169.
170.