全文获取类型
收费全文 | 44189篇 |
免费 | 3024篇 |
国内免费 | 16篇 |
出版年
2023年 | 276篇 |
2022年 | 605篇 |
2021年 | 1050篇 |
2020年 | 629篇 |
2019年 | 776篇 |
2018年 | 1107篇 |
2017年 | 906篇 |
2016年 | 1511篇 |
2015年 | 2275篇 |
2014年 | 2431篇 |
2013年 | 3313篇 |
2012年 | 3774篇 |
2011年 | 3539篇 |
2010年 | 2200篇 |
2009年 | 1867篇 |
2008年 | 2649篇 |
2007年 | 2588篇 |
2006年 | 2277篇 |
2005年 | 2065篇 |
2004年 | 1937篇 |
2003年 | 1854篇 |
2002年 | 1665篇 |
2001年 | 418篇 |
2000年 | 301篇 |
1999年 | 374篇 |
1998年 | 429篇 |
1997年 | 294篇 |
1996年 | 287篇 |
1995年 | 274篇 |
1994年 | 266篇 |
1993年 | 255篇 |
1992年 | 194篇 |
1991年 | 219篇 |
1990年 | 204篇 |
1989年 | 167篇 |
1988年 | 142篇 |
1987年 | 143篇 |
1986年 | 120篇 |
1985年 | 153篇 |
1984年 | 138篇 |
1983年 | 113篇 |
1982年 | 110篇 |
1981年 | 117篇 |
1980年 | 109篇 |
1979年 | 117篇 |
1978年 | 91篇 |
1977年 | 86篇 |
1976年 | 84篇 |
1974年 | 74篇 |
1973年 | 85篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Feldmane Daina Druva-Lūsīte Ieva Pole Valentīna Butac Mădălina Maria Militaru Mădălina Missa Imants Meiere Diāna Rubauskis Edgars 《Journal of Plant Growth Regulation》2021,40(2):533-540
Journal of Plant Growth Regulation - Sour cherry ‘Latvijas Zemais’ (Prunus cerasus) is a promising dwarfing rootstock for sweet cherries in Latvia, but low growing rate of newly... 相似文献
992.
Terzin Marko Paletta Maria Grazia Matterson Kenan Coppari Martina Bavestrello Giorgio Abbiati Marco Bo Marzia Costantini Federica 《Coral reefs (Online)》2021,40(4):1391-1391
Coral Reefs - A correction to this paper has been published: https://doi.org/10.1007/s00338-021-02120-y 相似文献
993.
da Silva Fernando Henrique Alves de Morais Patrícia Lígia Dantas da Silva Dias Nildo de Sousa Nunes Glauber Henrique de Morais Marciana Bizerra Melo Marlenildo Ferreira de Albuquerque Nascimento Maria Tereza 《Journal of Plant Growth Regulation》2021,40(3):1298-1314
Journal of Plant Growth Regulation - This study evaluated the effect of saline water irrigation (4.5 dS m−1) on growth, gas exchange and mineral nutrient content in eight melon accessions and... 相似文献
994.
de Sousa Sylvia Morais de Oliveira Christiane Abreu Andrade Daniele Luiz de Carvalho Chainheny Gomes Ribeiro Vitória Palhares Pastina Maria Marta Marriel Ivanildo Evódio de Paula Lana Ubiraci Gomes Gomes Eliane Aparecida 《Journal of Plant Growth Regulation》2021,40(2):867-877
Journal of Plant Growth Regulation - The rising demand for agricultural commodities in developing countries has put increasing pressure on land resources for higher yields, with associated growth... 相似文献
995.
Checchio Mirela Vantini de Cássia Alves Rita de Oliveira Kevein Ruas Moro Gustavo Vitti Santos Durvalina Maria Mathias dos Gratão Priscila Lupino 《Journal of plant research》2021,134(6):1279-1289
Journal of Plant Research - Salinity has become one of the major factors limiting agricultural production. In this regard, different cost-effective management strategies such as the use of plant... 相似文献
996.
Ana Carolina Galindo da Costa William Wayt Thomas Isabel Cristina Machado 《Plant Species Biology》2021,36(3):503-511
Ambophily (wind and insect pollination) has been reported for some genera of the typically wind-pollinated family Cyperaceae, including the genus Rhynchospora. The significance of wind and insect pollination can vary, depending on local microclimatic conditions. Rhynchospora cephalotes is an ambophilous species that can grow under different environmental conditions, either along forest edges or inside forest fragments. This study, therefore, tests the hypothesis that (a) there is greater contribution by wind than insects to fruit set of the individuals at the forest edge and (b) there is greater contribution by insects than wind to fruit set of the individuals inside the forest. Field work was carried out in a fragment of Atlantic Forest in northeastern Brazil. We quantified the number of visits by insects, wind velocity and the reproductive success (fruit set) of R. cephalotes provided by wind and insects through exclusion experiments performed at the edge of and inside the forest. We observed a greater number of visits per day by pollinating bees to individuals inside the forest (36.83 ± 7.46) than to individuals at the edge (16.66 ± 6.53). The wind speed was significantly higher at the edge (1.71 ± 0.46 m/s) than inside the forest (0.97 ± 0.18 m/s). Bees and wind are both pollen vectors of R. cephalotes, but bees were the pollen vector that contributed most to fruit set (63.3%) for individuals inside the forest, whereas wind was the primary vector for individuals at the forest edge (76.6%). This seesaw in importance of each pollen vector in the two different environments guarantees high fruit set in R. cephalotes under different microclimatic conditions. 相似文献
997.
Delgado Naranjo Juan Martin Jiménez Callejón Maria José Peñuela Vásquez Mariana Rios Luis Alberto Robles Medina Alfonso 《Journal of applied phycology》2021,33(4):2031-2045
Journal of Applied Phycology - The thraustochytrid Aurantiochytrium limacinum SR21 is a promising source of docosahexaenoic acid (DHA) for human consumption as dietary supplement, replacing... 相似文献
998.
Murray Kimberley R. Bird Melanie Strack Maria Cody Michael Xu Bin 《Wetlands Ecology and Management》2021,29(2):281-299
Wetlands Ecology and Management - Oil sands exploration activities across the Alberta boreal peatlands requires tree clearing and results in sites being left compressed and with altered understory... 相似文献
999.
Luana Lionetto Martina Ulivieri Matilde Capi Donatella De Bernardini Francesco Fazio Andrea Petrucca Leda Marina Pomes Ottavia De Luca Giovanna Gentile Barbara Casolla Martina Curto Gerardo Salerno Serena Schillizzi Maria Simona Torre Iolanda Santino Monica Rocco Paolo Marchetti Antonio Aceti Marina Borro 《生物化学与生物物理学报:疾病的分子基础》2021,1867(3):166042
Immune dysregulation is a hallmark of patients infected by SARS-CoV2 and the balance between immune reactivity and tolerance is a key determinant of all stages of infection, including the excessive inflammatory state causing the acute respiratory distress syndrome. The kynurenine pathway (KP) of tryptophan (Trp) metabolism is activated by pro-inflammatory cytokines and drives mechanisms of immune tolerance. We examined the state of activation of the KP by measuring the Kyn:Trp ratio in the serum of healthy subjects (n = 239), and SARS-CoV2-negative (n = 305) and -positive patients (n = 89). Patients were recruited at the Emergency Room of St. Andrea Hospital (Rome, Italy). Kyn and Trp serum levels were assessed by HPLC/MS-MS. Compared to healthy controls, both SARS-CoV2-negative and -positive patients showed an increase in the Kyn:Trp ratio. The increase was larger in SARS-CoV2-positive patients, with a significant difference between SARS-CoV2-positive and -negative patients. In addition, the increase was more prominent in males, and positively correlated with age and severity of SARS-CoV2 infection, categorized as follows: 1 = no need for intensive care unit (ICU); 2 ≤ 3 weeks spent in ICU; 3 ≥ 3 weeks spent in ICU; and 4 = death. The highest Kyn:Trp values were found in SARS-CoV2-positive patients with severe lymphopenia. These findings suggest that the Kyn:Trp ratio reflects the level of inflammation associated with SARS-CoV2 infection, and, therefore, might represent a valuable biomarker for therapeutic intervention. 相似文献
1000.
Manuella Maria Silva Santos Damián Gatica Jaqueline de Azêvedo Silva Sergio Crovella Daniel J. Klionsky Marcos Antonio De Morais Jr 《生物化学与生物物理学报:疾病的分子基础》2021,1867(4):166053
Mevalonate kinase deficiency (MKD) is an autosomal recessive disorder in humans that causes systemic autoinflammatory problems to children. Previously, we used a yeast model to show that MKD results in mitochondrial malfunctioning that may finally induce mitophagy. Here, we proved that MKD indeed induced general autophagy as well as mitophagy in yeast, but these mechanisms did not go to completion. Therefore, the limitation of mevalonate kinase activity produces dysfunctional mitochondria that might not be recycled, causing metabolic dysfunctions in the cells. Understanding this mechanism may provide a piece in solving the nonspecific autoinflammatory response puzzle observed in MKD patients. 相似文献