全文获取类型
收费全文 | 2801篇 |
免费 | 328篇 |
出版年
2023年 | 15篇 |
2022年 | 42篇 |
2021年 | 64篇 |
2020年 | 54篇 |
2019年 | 65篇 |
2018年 | 73篇 |
2017年 | 84篇 |
2016年 | 104篇 |
2015年 | 128篇 |
2014年 | 154篇 |
2013年 | 191篇 |
2012年 | 215篇 |
2011年 | 219篇 |
2010年 | 98篇 |
2009年 | 116篇 |
2008年 | 130篇 |
2007年 | 151篇 |
2006年 | 133篇 |
2005年 | 118篇 |
2004年 | 99篇 |
2003年 | 100篇 |
2002年 | 97篇 |
2001年 | 77篇 |
2000年 | 71篇 |
1999年 | 66篇 |
1998年 | 38篇 |
1997年 | 36篇 |
1996年 | 26篇 |
1995年 | 24篇 |
1994年 | 28篇 |
1993年 | 17篇 |
1992年 | 22篇 |
1991年 | 24篇 |
1990年 | 19篇 |
1989年 | 28篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 21篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1978年 | 9篇 |
1977年 | 14篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1972年 | 11篇 |
1969年 | 7篇 |
1967年 | 7篇 |
1966年 | 11篇 |
排序方式: 共有3129条查询结果,搜索用时 375 毫秒
131.
de Arruda Hélida Lídia Sousa dos Santos Juliana Ferrão Oliveira Albuquerque Ulysses Paulino Ramos Marcelo Alves 《Economic botany》2019,73(1):1-12
Economic Botany - We aim to evaluate whether socioeconomic factors influence the knowledge, use, preference, and consumption of firewood in a rural community in Northeast Brazil. We conducted... 相似文献
132.
Alison Pureza Castilho Joel Pasinato Jhulie Emille Veloso dos Santos Analia e Silva da Costa Dori Edson Nava Cristiane Ramos de Jesus Ricardo Adaime 《Revista Brasileira de Entomologia》2019,63(4):302-307
Bactrocera carambolae is a quarantine pest found in Brazil, restricted to the states of Amapá, Pará and Roraima. This fruit fly can potentially cause extensive socioeconomic and environmental damage in the country, if it disperse into areas where fruit is grown for exporting. The objective of this work was to study the biology of B. carambolae on fruits of Averrhoa carambola L. (Oxalidaceae), Psidium guajava L. (Myrtaceae), Spondias mombin L. (Anacardiaceae) and Eugenia stipitata McVaugh (Myrtaceae). The following parameters were investigated: duration of egg-larva, pupal, egg-adult, pre-oviposition, oviposition and post-oviposition periods, pupal weight and viability, sex ratio, fecundity, fertility and longevity. All parameters except pupal weight, oviposition and post-oviposition period, egg fertility and sex ratio were influenced by the host plant on which the larvae were reared. The carambola fruit fly completes its development on all those hosts studied here, with the highest fecundities on A. carambola and P. guajava. 相似文献
133.
Hade Ramos Anne Monette Meijuan Niu Aldo Barrera Brenda Lpez-Ulloa Yazmín Fuentes Paola Guizar Karla Pino Luc DesGroseillers Andrew
J Mouland Marcelo Lpez-Lastra 《Nucleic acids research》2022,50(1):411
Translation initiation of the viral genomic mRNA (vRNA) of human immunodeficiency virus-type 1 (HIV-1) can be mediated by a cap- or an internal ribosome entry site (IRES)-dependent mechanism. A previous report shows that Staufen1, a cellular double-stranded (ds) RNA-binding protein (RBP), binds to the 5’untranslated region (5′UTR) of the HIV-1 vRNA and promotes its cap-dependent translation. In this study, we now evaluate the role of Staufen1 as an HIV-1 IRES-transacting factor (ITAF). We first confirm that Staufen1 associates with both the HIV-1 vRNA and the Gag protein during HIV-1 replication. We found that in HIV-1-expressing cells, siRNA-mediated depletion of Staufen1 reduces HIV-1 vRNA translation. Using dual-luciferase bicistronic mRNAs, we show that the siRNA-mediated depletion and cDNA-mediated overexpression of Staufen1 acutely regulates HIV-1 IRES activity. Furthermore, we show that Staufen1-vRNA interaction is required for the enhancement of HIV-1 IRES activity. Interestingly, we find that only Staufen1 harboring an intact dsRNA-binding domain 3 (dsRBD3) rescues HIV-1 IRES activity in Staufen1 CRISPR-Cas9 gene edited cells. Finally, we show that the expression of Staufen1-dsRBD3 alone enhances HIV-1 IRES activity. This study provides evidence of a novel role for Staufen1 as an ITAF promoting HIV-1 vRNA IRES activity. 相似文献
134.
135.
136.
137.
Alireza Naghizadeh Wei-chung Tsao Jong Hyun Cho Hongye Xu Mohab Mohamed Dali Li Wei Xiong Dimitri Metaxas Carlos A. Ramos Dongfang Liu 《PLoS computational biology》2022,18(3)
The human immune system consists of a highly intelligent network of billions of independent, self-organized cells that interact with each other. Machine learning (ML) is an artificial intelligence (AI) tool that automatically processes huge amounts of image data. Immunotherapies have revolutionized the treatment of blood cancer. Specifically, one such therapy involves engineering immune cells to express chimeric antigen receptors (CAR), which combine tumor antigen specificity with immune cell activation in a single receptor. To improve their efficacy and expand their applicability to solid tumors, scientists optimize different CARs with different modifications. However, predicting and ranking the efficacy of different "off-the-shelf" immune products (e.g., CAR or Bispecific T-cell Engager [BiTE]) and selection of clinical responders are challenging in clinical practice. Meanwhile, identifying the optimal CAR construct for a researcher to further develop a potential clinical application is limited by the current, time-consuming, costly, and labor-intensive conventional tools used to evaluate efficacy. Particularly, more than 30 years of immunological synapse (IS) research data demonstrate that T cell efficacy is not only controlled by the specificity and avidity of the tumor antigen and T cell interaction, but also it depends on a collective process, involving multiple adhesion and regulatory molecules, as well as tumor microenvironment, spatially and temporally organized at the IS formed by cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. The optimal function of cytotoxic lymphocytes (including CTL and NK) depends on IS quality. Recognizing the inadequacy of conventional tools and the importance of IS in immune cell functions, we investigate a new strategy for assessing CAR-T efficacy by quantifying CAR IS quality using the glass-support planar lipid bilayer system combined with ML-based data analysis. Previous studies in our group show that CAR-T IS quality correlates with antitumor activities in vitro and in vivo. However, current manually quantified IS quality data analysis is time-consuming and labor-intensive with low accuracy, reproducibility, and repeatability. In this study, we develop a novel ML-based method to quantify thousands of CAR cell IS images with enhanced accuracy and speed. Specifically, we used artificial neural networks (ANN) to incorporate object detection into segmentation. The proposed ANN model extracts the most useful information to differentiate different IS datasets. The network output is flexible and produces bounding boxes, instance segmentation, contour outlines (borders), intensities of the borders, and segmentations without borders. Based on requirements, one or a combination of this information is used in statistical analysis. The ML-based automated algorithm quantified CAR-T IS data correlates with the clinical responder and non-responder treated with Kappa-CAR-T cells directly from patients. The results suggest that CAR cell IS quality can be used as a potential composite biomarker and correlates with antitumor activities in patients, which is sufficiently discriminative to further test the CAR IS quality as a clinical biomarker to predict response to CAR immunotherapy in cancer. For translational research, the method developed here can also provide guidelines for designing and optimizing numerous CAR constructs for potential clinical development.Trial Registration: ClinicalTrials.gov . NCT00881920相似文献
138.
139.
Involvement of the TonB system in tolerance to solvents and drugs in Pseudomonas putida DOT-T1E 下载免费PDF全文
Pseudomonas putida DOT-T1E is able to grow with glucose as the carbon source in liquid medium with 1% (vol/vol) toluene or 17 g of (123 mM) p-hydroxybenzoate (4HBA) per liter. After random mini-Tn5'phoA-Km mutagenesis, we isolated the mutant DOT-T1E-PhoA5, which was more sensitive than the wild type to 4HBA (growth was prevented at 6 g/liter) and toluene (the mutant did not withstand sudden toluene shock). Susceptibility to toluene and 4HBA resulted from the reduced efflux of these compounds from the cell, as revealed by accumulation assays with (14)C-labeled substrates. The mutant was also more susceptible to a number of antibiotics, and its growth in iron-deficient minimal medium was inhibited in the presence of ethylenediamine-di(o-hydroxyphenylacetic acid (EDDHA). Cloning the mutation in the PhoA5 strain and sequencing the region adjacent showed that the mini-Tn5 transposor interrupted the exbD gene, which forms part of the exbBD tonB operon. Complementation by the exbBD and tonB genes cloned in pJB3-Tc restored the wild-type characteristics to the PhoA5 strain. 相似文献
140.
Cloning and expression of two genes coding for sodium pumps in the salt-tolerant yeast Debaryomyces hansenii 下载免费PDF全文
Almagro A Prista C Benito B Loureiro-Dias MC Ramos J 《Journal of bacteriology》2001,183(10):3251-3255
Two genes encoding Na(+)-ATPases from Debaryomyces hansenii were cloned and sequenced. The genes, designated ENA1 from D. hansenii (DhENA1) and DhENA2, exhibited high homology with the corresponding genes from Schwanniomyces occidentalis. DhENA1 was expressed in the presence of high Na(+) concentrations, while the expression of DhENA2 also required high pH. A mutant of Saccharomyces cerevisiae lacking the Na(+) efflux systems and sensitive to Na(+), when transformed with DhENA1 or DhENA2, recovered Na(+) tolerance and also the ability to extrude Na(+). 相似文献