全文获取类型
收费全文 | 2310篇 |
免费 | 260篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 34篇 |
2020年 | 26篇 |
2019年 | 36篇 |
2018年 | 45篇 |
2017年 | 48篇 |
2016年 | 74篇 |
2015年 | 99篇 |
2014年 | 105篇 |
2013年 | 121篇 |
2012年 | 127篇 |
2011年 | 141篇 |
2010年 | 95篇 |
2009年 | 77篇 |
2008年 | 118篇 |
2007年 | 111篇 |
2006年 | 104篇 |
2005年 | 128篇 |
2004年 | 102篇 |
2003年 | 97篇 |
2002年 | 95篇 |
2001年 | 75篇 |
2000年 | 71篇 |
1999年 | 72篇 |
1998年 | 37篇 |
1997年 | 29篇 |
1996年 | 26篇 |
1995年 | 28篇 |
1994年 | 14篇 |
1993年 | 17篇 |
1992年 | 40篇 |
1991年 | 32篇 |
1990年 | 38篇 |
1989年 | 40篇 |
1988年 | 38篇 |
1987年 | 24篇 |
1986年 | 29篇 |
1985年 | 18篇 |
1984年 | 18篇 |
1983年 | 17篇 |
1982年 | 16篇 |
1981年 | 19篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1971年 | 8篇 |
排序方式: 共有2570条查询结果,搜索用时 406 毫秒
51.
52.
53.
Consuelo Díaz de la Guardia Roberto Alonso Francisca Alba Francisco Valle 《Aerobiologia》1995,11(1):47-50
We have carried out a study on the annual and daily pollen concentrations from Gramineae over four consecutive years in the atmosphere of Granada (Spain). Samples of pollen grains were collected by the volumetric method with the aid of a Burkard sporetrap. Gramineae, according both to their high sensitizing capacity and to data from allergologists, are responsible for many pollinoses diagnosed in this area. In this work, daily pollen levels from April to July are monitored and the variations identified are interpreted in relation to meteorological conditions. Results indicated that the highest airborne concentrations of Gramineae pollen were found in May and June, although the beginning and intensity of pollination have been variable during these 4 years. 相似文献
54.
Plasmid rolling circle replication and its control 总被引:10,自引:0,他引:10
Manuel Espinosa Gloria del Solar Fernando Rojo Juan C. Alonso 《FEMS microbiology letters》1995,130(2-3):111-120
Abstract This review summarises current information on rolling circle replicating plasmids originally isolated from Gram-positive bacteria with a low guanine and cytosine content in their DNA. It focuses on the peculiar biological features of these small, high copy number plasmids that replicate via an asymmetric RC mechanism. The regulation of plasmid copy number is also discussed. 相似文献
55.
Cuvillier Olivier; Alonso Catherine; Wieruszeski Jean-Michel; Brassart Colette; Strecker Gerard; Bouquelet Stephane; Michalski Jean-Claude 《Glycobiology》1995,5(3):281-289
During a systematic study of carbohydrate material present inhuman meconium, in addition to the previously described mucins,glycolipids and free oligosaccharides, we have now characterizeda significant quantity of free glycoasparagines. These glycoasparagineshave been isolated from human meconium by a combination of ion-exchange,concanavalin A (ConA)-affinity and high-performance liquid (HPLC)chromatographies. Their structures have been established by400 MHz 1H-NMR spectroscopy. These compounds are related toN-acetyllactosaminic type structures and are based on the commoncore These glycoasparagines are probably derived from both proteaseand partial exoglycosidase hydrolysis of fetal gastrointestinalN-glycosyl proteins. Their structures are discussed in the contextof the known catabolic pathways of N-glycans glycoasparagine N-glycosyl protein catabolism meconium NMR 相似文献
56.
We compare a recombinant cDNA plasmid (pAF81) complementary to a fetal skeletal muscle actin mRNA with a plasmid (pAM91) complementary to the actin mRNA expressed in adult skeletal muscle. The two mRNAs are significantly diverged in silent nucleotide positions; they are coexpressed in fetal skeletal muscle, and in differentiating muscle cell cultures their accumulation begins coordinately. The sequence of pAF81 shows that the amino acid sequence of mouse fetal skeletal muscle actin is almost identical to that of adult bovine cardiac actin. Hybridization of pAF81 to RNA from different mouse tissues shows that fetal skeletal muscle actin mRNA is very homologous or identical to fetal and adult cardiac actin mRNA. Only one gene homologous to pAF81 is detected on blots of restricted mouse DNA. We conclude that this gene must be expressed both in fetal skeletal muscle and in fetal heart. Whereas mRNA transcribed from this gene is the major actin mRNA species in adult heart, it is present in low amounts, if at all, in adult skeletal muscle. 相似文献
57.
58.
Alicia Alonso Colin J. Restall Margaret Turner Juan C. Gomez-Fernandez Felix M. Goñi Dennis Chapman 《生物化学与生物物理学报:生物膜》1982,689(2):283-289
Bacteriorhodopsin has been reconstituted at various molar concentrations into liposomes of dimyristoyl- and also of dipalmitoylphosphatidylcholine. Differential scanning calorimetry indicates that as the protein concentration within the lipid bilayer increases, the cooperativity of the lipid phase transition is reduced, i.e. the transition is broadened, while the midpoint transition temperature remains virtually unchanged. Freeze-fracture electron microscopy of our preparation shows, in agreement with previous data from other laboratories, that extensive protein aggregation occurs when the liposome is cooled below the Tc transition temperature of the lipid. Laser flash photolysis measurements of protein rotation of the bacteriorhodopsin show, especially in the case of protein-rich recombinants, that protein aggregates exist even above Tc. The perturbation caused by the presence of bacteriorhodopsin in the lipid bilayer is similar to that produced by other intrinsic proteins. The difficulty of correlating the observed calorimetric enthalpy data with a simple concept of a ‘boundary lipid layer’ based upon consideration of a single isolated protein is discussed in view of the occurrence of protein aggregates both above and below Tc. It is concluded that the reduction of enthalpy is related to the number of lipids which solvate the protein aggregates within the protein-lipid patches and are thereby removed from the cooperative melting and enthalpy of the remaining regions of pure lipid. 相似文献
59.
60.
G Strecker J M Wieruszeski J C Michalski C Alonso B Boilly J Montreuil 《FEBS letters》1992,298(1):39-43
Novel acidic oligosaccharides were isolated in large amounts by reductive alkaline treatment of the jelly coat of Pleurodeles waltlii (Michah) eggs. The oligosaccharides were found to contain the newly described KDN as acidic monosaccharide and possess either the Le(x), Le(y) and A Le(y) antigenic determinants. Occurrence of Le(x) and Le(y) determinants previously recognized as tumor-associated antigen (TAA) demonstrates that mucins of lower animals may represent a rich and easily available source for preparing TAA. Moreover, it reinforces the hypothesis according to which TAA are evolution markers. 相似文献