全文获取类型
收费全文 | 13596篇 |
免费 | 888篇 |
国内免费 | 3篇 |
专业分类
14487篇 |
出版年
2023年 | 80篇 |
2022年 | 160篇 |
2021年 | 271篇 |
2020年 | 202篇 |
2019年 | 272篇 |
2018年 | 329篇 |
2017年 | 303篇 |
2016年 | 472篇 |
2015年 | 691篇 |
2014年 | 748篇 |
2013年 | 953篇 |
2012年 | 1144篇 |
2011年 | 1065篇 |
2010年 | 679篇 |
2009年 | 632篇 |
2008年 | 826篇 |
2007年 | 789篇 |
2006年 | 784篇 |
2005年 | 669篇 |
2004年 | 606篇 |
2003年 | 607篇 |
2002年 | 536篇 |
2001年 | 96篇 |
2000年 | 82篇 |
1999年 | 99篇 |
1998年 | 120篇 |
1997年 | 122篇 |
1996年 | 111篇 |
1995年 | 91篇 |
1994年 | 89篇 |
1993年 | 85篇 |
1992年 | 66篇 |
1991年 | 58篇 |
1990年 | 47篇 |
1989年 | 47篇 |
1988年 | 37篇 |
1987年 | 27篇 |
1986年 | 29篇 |
1985年 | 46篇 |
1984年 | 38篇 |
1983年 | 38篇 |
1982年 | 40篇 |
1981年 | 45篇 |
1980年 | 32篇 |
1979年 | 30篇 |
1978年 | 28篇 |
1977年 | 20篇 |
1975年 | 22篇 |
1974年 | 19篇 |
1973年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Waldemar Lernhardt Jan Andersson Antonio Coutinho Fritz Melchers 《Experimental cell research》1978,111(2):309-316
Addition of 3 × 106 thymus cells from either syngeneic, allogeneic or xenogeneic animals increases the cloning efficiencies of murine thymomas (EL-4, WC-2), B-lymphomas (McPC 1748, 38C-13), Abelson-virus transformed cell lines (F and K), mastocytomas (P815), myelomas (AbPC22, X63-AG8, 5563, MOPC 104 E, RFC 5, W 3469) and hybrids of myelomas and normal B-lymphocytes (Sp-1), all adapted to tissue culture, to near 100%. Thymus cells also increase the efficiencies of growth initiation in primary in vitro cultures of myeloma tumor cells (S117) transplanted in vivo, and of cells fused between the azaguanine-resistant X63-AG8 myeloma cell line and normal, LPS-stimulated B-lymphocyte blasts. 相似文献
83.
Raffaella Ponassi Barbara Biasotti Valeria Tomati Silvia Bruno Alessandro Poggi Davide Malacarne Guido Cimoli Annalisa Salis Sarah Pozzi Maurizio Miglino Gianluca Damonte Pietro Cozzini Francesca Spyrakis Barbara Campanini Luca Bagnasco Nicoletta Castagnino Lorenzo Tortolina Anna Mumot Francesco Frassoni Antonio Daga Michele Cilli Federica Piccardi Ilaria Monfardini Miriam Perugini Gabriele Zoppoli Cristina D’Arrigo Raffaele Pesenti Silvio Parodi 《Cell cycle (Georgetown, Tex.)》2012,11(19):3703
84.
Pere P. Simarro Giuliano Cecchi José R. Franco Massimo Paone Abdoulaye Diarra José Antonio Ruiz-Postigo Eric M. Fèvre Raffaele C. Mattioli Jean G. Jannin 《PLoS neglected tropical diseases》2012,6(10)
Background
Human African trypanosomiasis (HAT), also known as sleeping sickness, persists as a public health problem in several sub-Saharan countries. Evidence-based, spatially explicit estimates of population at risk are needed to inform planning and implementation of field interventions, monitor disease trends, raise awareness and support advocacy. Comprehensive, geo-referenced epidemiological records from HAT-affected countries were combined with human population layers to map five categories of risk, ranging from “very high” to “very low,” and to estimate the corresponding at-risk population.Results
Approximately 70 million people distributed over a surface of 1.55 million km2 are estimated to be at different levels of risk of contracting HAT. Trypanosoma brucei gambiense accounts for 82.2% of the population at risk, the remaining 17.8% being at risk of infection from T. b. rhodesiense. Twenty-one million people live in areas classified as moderate to very high risk, where more than 1 HAT case per 10,000 inhabitants per annum is reported.Discussion
Updated estimates of the population at risk of sleeping sickness were made, based on quantitative information on the reported cases and the geographic distribution of human population. Due to substantial methodological differences, it is not possible to make direct comparisons with previous figures for at-risk population. By contrast, it will be possible to explore trends in the future. The presented maps of different HAT risk levels will help to develop site-specific strategies for control and surveillance, and to monitor progress achieved by ongoing efforts aimed at the elimination of sleeping sickness. 相似文献85.
86.
Luiz Henrique Soares de Andrade Wilson Max Almeida Monteiro de Moraes Eduardo Hiroshi Matsuo Junior Elizabeth de Orleans Carvalho de Moura Hanna Karen Moreira Antunes Jairo Montemor Ednei Luiz Antonio Danilo Sales Bocalini Andrey Jorge Serra Paulo José Ferreira Tucci Patricia Chakur Brum Alessandra Medeiros 《Molecular and cellular biochemistry》2015,402(1-2):193-202
87.
Heredia-Rojas JA Caballero-Hernandez DE Rodriguez-de la Fuente AO Ramos-Alfano G Rodriguez-Flores LE 《Bioelectromagnetics》2004,25(1):63-68
The effect of in vivo exposure of mice to a 60 Hz sinusoidal magnetic field (MF) at 2.0 mT on male germ cells was studied. The cytological endpoints measured included meiotic chromosome aberrations in spermatocytes and sperm morphology. Three independent experiments were carried out: (a) animals exposed for 72 h, (b) 10 days/8 h daily, and (c) 72 h exposure to MF plus 5 mg/kg of Mitomycin-C. No statistically significant differences indicative of MF effects were observed between MF exposed and control animals. In addition, an opposite effect between MF exposure and Mitomycin-C treatment in terms of chromosomal aberrations and sperm morphology was observed. 相似文献
88.
89.
HOTAIR role in melanoma progression and its identification in the blood of patients with advanced disease 下载免费PDF全文
90.
Marina Lozano Almudena Estalrrich Luca Bondioli Ivana Fiore José‐Maria Bermúdez de Castro Juan Luis Arsuaga Eudald Carbonell Antonio Rosas David W. Frayer 《Evolutionary anthropology》2017,26(6):313-324
Fossil hominids often processed material held between their upper and lower teeth. Pulling with one hand and cutting with the other, they occasionally left impact cut marks on the lip (labial) surface of their incisors and canines. From these actions, it possible to determine the dominant hand used. The frequency of these oblique striations in an array of fossil hominins documents the typically modern pattern of 9 right‐ to 1 left‐hander. This ratio among living Homo sapiens differs from that among chimpanzees and bonobos and more distant primate relatives. Together, all studies of living people affirm that dominant right‐handedness is a uniquely modern human trait. The same pattern extends deep into our past. Thus far, the majority of inferred right‐handed fossils come from Europe, but a single maxilla from a Homo habilis, OH‐65, shows a predominance of right oblique scratches, thus extending right‐handedness into the early Pleistocene of Africa. Other studies show right‐handedness in more recent African, Chinese, and Levantine fossils, but the sample compiled for non‐European fossil specimens remains small. Fossil specimens from Sima del los Huesos and a variety of European Neandertal sites are predominately right‐handed. We argue the 9:1 handedness ratio in Neandertals and the earlier inhabitants of Europe constitutes evidence for a modern pattern of handedness well before the appearance of modern Homo sapiens. 相似文献