全文获取类型
收费全文 | 1395篇 |
免费 | 137篇 |
国内免费 | 86篇 |
出版年
2024年 | 5篇 |
2023年 | 11篇 |
2022年 | 43篇 |
2021年 | 71篇 |
2020年 | 35篇 |
2019年 | 55篇 |
2018年 | 38篇 |
2017年 | 27篇 |
2016年 | 47篇 |
2015年 | 85篇 |
2014年 | 103篇 |
2013年 | 98篇 |
2012年 | 125篇 |
2011年 | 113篇 |
2010年 | 59篇 |
2009年 | 52篇 |
2008年 | 61篇 |
2007年 | 67篇 |
2006年 | 61篇 |
2005年 | 43篇 |
2004年 | 41篇 |
2003年 | 56篇 |
2002年 | 39篇 |
2001年 | 31篇 |
2000年 | 26篇 |
1999年 | 22篇 |
1998年 | 12篇 |
1997年 | 15篇 |
1996年 | 10篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 12篇 |
1992年 | 21篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1985年 | 7篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1970年 | 2篇 |
排序方式: 共有1618条查询结果,搜索用时 46 毫秒
91.
Dach1 mutant mice bear no gross abnormalities in eye, limb, and brain development and exhibit postnatal lethality
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Davis RJ Shen W Sandler YI Amoui M Purcell P Maas R Ou CN Vogel H Beaudet AL Mardon G 《Molecular and cellular biology》2001,21(5):1484-1490
Drosophila dachshund is necessary and sufficient for compound eye development and is required for normal leg and brain development. A mouse homologue of dachshund, Dach1, is expressed in the developing retina and limbs, suggesting functional conservation of this gene. We have generated a loss-of-function mutation in Dach1 that results in the abrogation of the wild-type RNA and protein expression pattern in embryos. Homozygous mutants survive to birth but exhibit postnatal lethality associated with a failure to suckle, cyanosis, and respiratory distress. The heart, lungs, kidneys, liver, and skeleton were examined to identify factors involved in postnatal lethality, but these organs appeared to be normal. In addition, blood chemistry tests failed to reveal differences that might explain the lethal phenotype. Gross examination and histological analyses of newborn eyes, limbs, and brains revealed no detectable abnormalities. Since Dach1 mutants die shortly after birth, it remains possible that Dach1 is required for postnatal development of these structures. Alternatively, an additional Dach homologue may functionally compensate for Dach1 loss of function. 相似文献
92.
利用放射性同位素示踪技术研究了14C标记菲在有控系统中的迁移转化。结果表明,14C-菲在有控系统中降解较快,施入药品24d后仅有0.32%的14C-菲存留在植物、营养液和火山石中。植物吸收的14C放射性大部分被结合到植物组织中,其它14C主要以菲的极性代谢物形态存在。 相似文献
93.
94.
95.
Dong‐Bo Ou Hong‐Juan Lang Rui Chen Xiong‐Tao Liu Qiang‐Sun Zheng 《BioEssays : news and reviews in molecular, cellular and developmental biology》2009,31(2):246-252
Biological pacemakers can be achieved by various gene‐based and cell‐based approaches. Embryonic stem cells (ESCs)‐derived pacemaker cells might be the most promising way to form biological pacemakers, but there are challenges as to how to control the differentiation of ESCs and to overcome the neoplasia, proarrhythmia, or immunogenicity resulting from the use of ESCs. As a potential approach to solve these difficult problems, tissue‐engineering techniques may provide a precise control on the different cell components of multicellular aggregates and the forming of a construct with‐defined architectures and functional properties. The combined interactions between ESC‐derived pacemaker cells, supporting cells, and matrices may completely reproduce pacemaker properties and result in a steady functional unit to induce rhythmic electrical and contractile activities. As ESCs have a high capability for self‐renewal, proliferation, and potential differentiation, we hypothesize that ESCs can be used as a source of pacemaker cells for tissue‐engineering applications and the ambitious goal of biological cardiac pacemakers may ultimately be achieved with ESCs via tissue‐engineering technology. 相似文献
96.
The emergence of NDM-1 containing multi-antibiotic resistant "Superbugs" necessitates the needs of developing of novel NDM-1inhibitors. In this study, we report the discovery of novel NDM-1 inhibitors by multi-step virtual screening. From a 2,800,000 virtual drug-like compound library selected from the ZINC database, we generated a focused NDM-1 inhibitor library containing 298 compounds of which 44 chemical compounds were purchased and evaluated experimentally for their ability to inhibit NDM-1 in vitro. Three novel NDM-1 inhibitors with micromolar IC50 values were validated. The most potent inhibitor, VNI-41, inhibited NDM-1 with an IC50 of 29.6 ± 1.3 μM. Molecular dynamic simulation revealed that VNI-41 interacted extensively with the active site. In particular, the sulfonamide group of VNI-41 interacts directly with the metal ion Zn1 that is critical for the catalysis. These results demonstrate the feasibility of applying virtual screening methodologies in identifying novel inhibitors for NDM-1, a metallo-β-lactamase with a malleable active site and provide a mechanism base for rational design of NDM-1 inhibitors using sulfonamide as a functional scaffold. 相似文献
97.
Manfred Accrombessi Sma?la Ouédraogo Gino Cédric Agbota Raquel Gonzalez Achille Massougbodji Clara Menéndez Michel Cot 《PloS one》2015,10(6)
Background
Anaemia is an increasingly recognized health problem in Africa, particularly in infants and pregnant women. Although malaria is known to be the main risk factor of anaemia in both groups, the consequences of maternal factors, particularly malaria in pregnancy (MiP), on infant haemoglobin (Hb) concentrations during the first months of life are still unclear.Methods
We followed-up a cohort of 1005 Beninese pregnant women from the beginning of pregnancy until delivery. A subsample composed of the first 400 offspring of these women were selected at birth and followed until the first year of life. Placental histology and blood smear at 1st clinical antenatal visit (ANC), 2nd ANC and delivery were used to assess malaria during pregnancy. Infant Hb concentrations were measured at birth, 6, 9 and 12 months of age. A mixed multi-level model was used to assess the association between MiP and infant Hb variations during the first 12 months of life.Results
Placental malaria (difference mean [dm] = - 2.8 g/L, 95% CI [-5.3, -0.3], P = 0.03) and maternal peripheral parasitaemia at delivery (dm = - 4.6 g/L, 95% CI [-7.9, -1.3], P = 0.007) were the main maternal factors significantly associated with infant Hb concentrations during the first year of life. Poor maternal nutritional status and malaria infection during infancy were also significantly associated with a decrease in infant Hb.Conclusion
Antimalarial control and nutritional interventions before and during pregnancy should be reinforced to reduce specifically the incidence of infant anaemia, particularly in Sub-Saharan countries. 相似文献98.
99.
100.
A purification process for heparin and precursor polysaccharides using the pH responsive behavior of chitosan
下载免费PDF全文
![点击此处可从《Biotechnology progress》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ujjwal Bhaskar Anne M. Hickey Guoyun Li Ruchir V. Mundra Fuming Zhang Li Fu Chao Cai Zhimin Ou Jonathan S. Dordick Robert J. Linhardt 《Biotechnology progress》2015,31(5):1348-1359
The contamination crisis of 2008 has brought to light several risks associated with use of animal tissue derived heparin. Because the total chemical synthesis of heparin is not feasible, a bioengineered approach has been proposed, relying on recombinant enzymes derived from the heparin/HS biosynthetic pathway and Escherichia coli K5 capsular polysaccharide. Intensive process engineering efforts are required to achieve a cost‐competitive process for bioengineered heparin compared to commercially available porcine heparins. Towards this goal, we have used 96‐well plate based screening for development of a chitosan‐based purification process for heparin and precursor polysaccharides. The unique pH responsive behavior of chitosan enables simplified capture of target heparin or related polysaccharides, under low pH and complex solution conditions, followed by elution under mildly basic conditions. The use of mild, basic recovery conditions are compatible with the chemical N‐deacetylation/N‐sulfonation step used in the bioengineered heparin process. Selective precipitation of glycosaminoglycans (GAGs) leads to significant removal of process related impurities such as proteins, DNA and endotoxins. Use of highly sensitive liquid chromatography‐mass spectrometry and nuclear magnetic resonance analytical techniques reveal a minimum impact of chitosan‐based purification on heparin product composition. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1348–1359, 2015 相似文献