全文获取类型
收费全文 | 3778篇 |
免费 | 294篇 |
专业分类
4072篇 |
出版年
2024年 | 7篇 |
2023年 | 42篇 |
2022年 | 99篇 |
2021年 | 125篇 |
2020年 | 132篇 |
2019年 | 126篇 |
2018年 | 161篇 |
2017年 | 133篇 |
2016年 | 199篇 |
2015年 | 238篇 |
2014年 | 253篇 |
2013年 | 306篇 |
2012年 | 335篇 |
2011年 | 284篇 |
2010年 | 158篇 |
2009年 | 165篇 |
2008年 | 178篇 |
2007年 | 172篇 |
2006年 | 143篇 |
2005年 | 123篇 |
2004年 | 93篇 |
2003年 | 88篇 |
2002年 | 84篇 |
2001年 | 56篇 |
2000年 | 62篇 |
1999年 | 60篇 |
1998年 | 9篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 16篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 16篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1971年 | 6篇 |
1968年 | 3篇 |
1967年 | 4篇 |
排序方式: 共有4072条查询结果,搜索用时 0 毫秒
991.
Renan Janke Bosque Jente Ottenburghs Cecília Rodrigues Vieira Fabrícius Maia Chaves Bicalho Domingos 《Evolution; international journal of organic evolution》2020,74(11):2541-2543
Mimicry can directly affect the evolutionary history of models, mimics, and signal receivers. Mimics often use multimodal signaling to deceive receivers. Jamie et al. showed that brood parasitic birds display multimodal signaling of mimetic traits triggered by sexual and filial imprinting on host species. These resulting adaptations can interact with premating isolation barriers to strengthen reproductive isolation and potentially drive sympatric speciation. 相似文献
992.
Patricia Fernanda Rocha-Dias Daiane Priscila Simao-Silva Saritha Suellen Lopes da Silva Mauro Roberto Piovezan Ricardo Krause M. Souza Taher. Darreh-Shori Lupe Furtado-Alle Ricardo Lehtonen Rodrigues Souza 《Genetics and molecular biology》2020,43(4)
The choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) are fundamental to neurophysiological functions of the central cholinergic system. We confirmed and quantified the presence of extracellular ChAT protein in human plasma and also characterized ChAT and VAChT polymorphisms, protein and activity levels in plasma of Alzheimer''s disease patients (AD; N = 112) and in cognitively healthy controls (EC; N = 118). We found no significant differences in plasma levels of ChAT activity and protein between AD and EC groups. Although no differences were observed in plasma ChAT activity and protein concentration among ChEI-treated and untreated AD patients, ChAT activity and protein levels variance in plasma were higher among the rivastigmine-treated group (ChAT protein: p = 0.005; ChAT activity: p = 0.0002). Moreover, AD patients homozygous for SNP rs1880676 A allele exhibited higher levels of ChAT activity. Considering this is the first study to report the influence of genetic variability of CHAT locus over ChAT activity in AD patients plasma, it opens a new set of important questions on peripheral cholinergic signaling in AD. 相似文献
993.
Sheron Campos Cogo Thatyanne Gradowski Farias da Costa do Nascimento Fernanda de Almeida Brehm Pinhatti Nilton de Frana Junior Bruna Santos Rodrigues Luciane Regina Cavalli Selene Elifio-Esposito 《Experimental biology and medicine (Maywood, N.J.)》2020,245(18):1637
This review was conducted to present the main neuroblastoma (NB) clinical characteristics and the most common genetic alterations present in these pediatric tumors, highlighting their impact in tumor cell aggressiveness behavior, including metastatic development and treatment resistance, and patients’ prognosis. The distinct three NB cell lineage phenotypes, S-type, N-type, and I-type, which are characterized by unique cell surface markers and gene expression patterns, are also reviewed. Finally, an overview of the most used NB cell lines currently available for in vitro studies and their unique cellular and molecular characteristics, which should be taken into account for the selection of the most appropriate model for NB pre-clinical studies, is presented. These valuable models can be complemented by the generation of NB reprogrammed tumor cells or organoids, derived directly from patients’ tumor specimens, in the direction toward personalized medicine. 相似文献
994.
da Silva Mendes Johnatan Wellisson Cunha Walmir Emanuel Miranda Rodrigues Fábio Fernandes Galvão Silveira Edilberto Rocha de Lima Roberta Dávila Pereira da Costa José Galberto Martins 《Phytochemistry Reviews》2020,19(4):955-982
Phytochemistry Reviews - Species of Cissampelos (Menispermaceae) are widely used in folk medicine in various cultures, for the treatment of a wide variety of diseases. Several ethnobotanical... 相似文献
995.
Ramos Lucas Rodrigues de Menezes Camila Aparecida Soares Laís Américo Sakamoto Isabel Kimiko Varesche Maria Bernadete Amâncio Silva Edson Luiz 《Bioprocess and biosystems engineering》2020,43(4):673-684
Bioprocess and Biosystems Engineering - This study assessed the effects of hydraulic retention time (HRT; 8 h–0.25 h) on simultaneous hydrogen and methane production from... 相似文献
996.
Takahashi Juliana Possatto Fernandes Feliciano Leticia Marielle Santos Dayane Cristina Silva Ramos Silézia Oliveira Rogério A. Attili-Angelis Derlene Rodrigues Nadia Regina Sampaio Jorge Luiz Mello dos Anjos Martins Marilena Melhem Marcia Souza Carvalho 《Current fungal infection reports》2020,14(1):9-14
Current Fungal Infection Reports - Acquired resistance among fungal strains is a growing concern. The reasons for the emergence of this phenomenon, with great clinical implications, are only... 相似文献
997.
Mirelen Moura de Oliveira Rodrigues Gabriela Hher Gabriela Waskow Mara Helena Hutz Juliana Dal-Ri Lindenau Maria Luiza Petzl-Erler Sidia Maria Callegari-Jacques Silvana Almeida Marilu Fiegenbaum 《Genetics and molecular biology》2021,44(2)
The study presents comparisons between blood group frequencies beyond ABO and Rh blood systems in Native American populations and previously published data from Brazilian blood donors. The frequencies of Diego (c.2561C>T, rs2285644), Kell (c.578C>T, rs8176058), Duffy (c.125A>G, rs12075, c.1−67T>C, rs2814778) and Kidd (c.838A>G, rs1058396) variants in Kaingang (n=72) and Guarani (n=234) populations from Brazil (1990-2000) were obtained and compared with data from these populations sampled during the 1960s and with individuals of different Brazilian regions. Data showed high frequencies of DI*01 and FY*01 alleles: 11.8% and 57.6% in Kaingang and 6.8% and 75.7% in Guarani groups, respectively. The main results indicated: (1) reduction in genetic distance over time of Kaingang and Guarani in relation to other Brazilian populations is suggestive of ongoing admixture; (2) significant differences in some frequencies of blood group markers (especially Diego, Kidd and Duffy) in relation to Native Americans and individuals from different geographical regions of Brazil. Our study shows that the frequency of red blood cell polymorphisms in two Native American groups is very different from that of blood donors, when we evaluated blood groups different from ABO and Rh systems, suggesting that a better ethnic characterization of blood unit receptors is necessary. 相似文献
998.
Severino Jefferson Ribeiro da Silva Jessica Catarine Frutuoso do Nascimento Wendell Palôma Maria dos Santos Reis Caroline Targino Alves da Silva Poliana Gomes da Silva Renata Pessôa Germano Mendes Allyson Andrade Mendonça Bárbara Nazly Rodrigues Santos Jurandy Júnior Ferraz de Magalhães Alain Kohl Lindomar Pena 《Environmental microbiology》2021,23(12):7382-7395
Although SARS-CoV-2 surface contamination has been investigated in health care settings, little is known about the SARS-CoV-2 surface contamination in public urban areas, particularly in tropical countries. Here, we investigated the presence of SARS-CoV-2 on high-touch surfaces in a large city in Brazil, one of the most affected countries by the COVID-19 pandemic in the world. A total of 400 surface samples were collected in February 2021 in the City of Recife, Northeastern Brazil. A total of 97 samples (24.2%) tested positive for SARS-CoV-2 by RT-qPCR using the CDC-USA protocol. All the collection sites, except one (18/19, 94.7%) had at least one environmental surface sample contaminated. SARS-CoV-2 positivity was higher in public transport terminals (47/84, 55.9%), followed by health care units (26/84, 30.9%), beach areas (4/21, 19.0%), public parks (14/105, 13.3%), supply centre (2/21, 9.5%), and public markets (4/85, 4.7%). Toilets, ATMs, handrails, playgrounds and outdoor gyms were identified as fomites with the highest rates of SARS-CoV-2 detection. Taken together, our data provide a real-world picture of SARS-CoV-2 dispersion in highly populated tropical areas and identify critical control points that need to be targeted to break SARS-CoV-2 transmission chains. 相似文献
999.
Paulo U. Carnaúba Ana C. Mengarda Vinícius C. Rodrigues Thiago R. Morais Alberto de Oliveira João Henrique G. Lago Josué de Moraes 《化学与生物多样性》2021,18(10):e2100503
Infections caused by parasitic worms impose a considerable worldwide health burden. One of the most impactful is schistosomiasis, a disease caused by blood-dwelling of the genus Schistosoma that affects more than 230 million people worldwide. Since praziquantel has also been extensively used to treat schistosomiasis and other parasitic flatworm infections, there is an urgent need to identify novel anthelmintic compounds, mainly from natural sources. In this study, the hexane extract from roots of Piper malacophyllum (Piperaceae) showed to be mainly composed for gibbilimbol B by HPLC/ESI-HRMS. Based on this result, this compound was isolated by chromatographic steps and its structure was confirmed by NMR. In vitro bioassays showed that gibbilimbol B was more active than praziquantel against larval stage of S. mansoni, with effective concentrations of 50 % (EC50) and 90 % (EC90) values of 2.6 and 3.4 μM, respectively. Importantly, gibbilimbol B showed no cytotoxicity to mammalian cells at a concentration 190 times greater than the antiparasitic effect, giving support for the anthelmintic potential of gibbilimbol B as lead compound for novel antischistosomal agents. 相似文献
1000.
Rapidly expanding use of biologging devices is increasingly bringing novel insights into ornithology. Consequently, to maximize bird welfare and data quality, this growth calls for ensuring that devices are properly attached. Here, we provide a diagram for constructing a simple, field‐adjustable leg‐loop harness suitable for many small and medium‐sized birds (< 200 g). We make harnesses prior to fieldwork using Teflon ribbon and a single crimp, then custom‐fit each harness to birds in the field. This largely removes the need for pre‐deployment field trials to determine harness size and ensures best possible fit. To evaluate the effects of harnesses on birds in the field, we marked 10 non‐migratory species in central Amazonia and assessed their body mass at recapture with linear mixed models. Of 90 tags deployed, we recovered 43 (48%) an average of 359 days later. No individuals lost their tag. Additionally, when recaptures were compared to original captures, body mass was not lower for either tagged birds or 17 banded‐only birds. This suggests that tags attached with our harness had little effect on birds, an encouraging result at a time when increasing options for tracking birds challenge researchers to properly attach various types of devices. 相似文献