全文获取类型
收费全文 | 4824篇 |
免费 | 469篇 |
出版年
2022年 | 30篇 |
2021年 | 69篇 |
2020年 | 38篇 |
2019年 | 51篇 |
2018年 | 54篇 |
2017年 | 52篇 |
2016年 | 80篇 |
2015年 | 167篇 |
2014年 | 194篇 |
2013年 | 255篇 |
2012年 | 300篇 |
2011年 | 303篇 |
2010年 | 209篇 |
2009年 | 201篇 |
2008年 | 248篇 |
2007年 | 250篇 |
2006年 | 251篇 |
2005年 | 250篇 |
2004年 | 227篇 |
2003年 | 202篇 |
2002年 | 186篇 |
2001年 | 50篇 |
2000年 | 41篇 |
1999年 | 54篇 |
1998年 | 53篇 |
1997年 | 45篇 |
1996年 | 36篇 |
1995年 | 44篇 |
1994年 | 43篇 |
1993年 | 45篇 |
1992年 | 46篇 |
1991年 | 32篇 |
1990年 | 46篇 |
1989年 | 47篇 |
1988年 | 32篇 |
1987年 | 45篇 |
1986年 | 28篇 |
1984年 | 50篇 |
1983年 | 46篇 |
1982年 | 54篇 |
1981年 | 39篇 |
1980年 | 38篇 |
1978年 | 35篇 |
1976年 | 28篇 |
1974年 | 36篇 |
1973年 | 31篇 |
1971年 | 29篇 |
1970年 | 31篇 |
1968年 | 25篇 |
1965年 | 30篇 |
排序方式: 共有5293条查询结果,搜索用时 31 毫秒
151.
Thirteen new congenic lines have been produced which have chromosome-7 segments introduced from different strains onto the C57BL/10Sn background. Sublines B10.P(61NX)C,D, and E received chromosome-7 segments from P/J, B10.CE(62NX) from CE/J, B10.SEC(64NX)A,C,E, and F from SEC/1Re, B10.SM(65NX) from SM/J, B10.WB(66NX) from WB/Re, B10.A(67NX) from A/SnGrf, B10.AKR(68NX) from AKR/SnGrf, and B10.K(69NX) from C3H.K. Isograft testing indicated that three sublines, B10.P(61NX)D, B10.CE(62NX)B, and B10.WB(66NX)B are histoisogenic, i.e., histocompatible within each line. With the exception of B10.A(67NX), B10.AK(68NX), and B10.K(69NX), which have not been isografted, the remaining sublines showed residual heterozygosity on isografting. The three histoisogenic lines have undergone F1 testing and have been found to possess theH-4
a
allele and new and distinct alleles at theH-1 locus. They have been designated B10.P(61NX)-H-4a
H-1
d
, B10.WB(66NX)-H-4a
H-1
e
, and B10.CE(62NX)-H-4a
H-1
f
. Direct exchange of grafts has indicated the following genotypes: B10.A(67NX)-H-4a
H-1
b
, B10.AK(68NX)-H-4a
H-1
b
, and B10.K(69NX)-F-4a
H-1
b
. The B10.SEC(64NX) and B10.SM(65NX) sublines have not been typed completely forH-4 andH-1. F
1
testing or direct exchange of skin grafts indicated that B10.P(61NX)-H-4a
H-1
d
, B10.WB(66NX)-H-4a
H-1
e
, B10.A(67NX)-H-4a
H-1
b
B10.AK(68NX)-H-4a
H-1
b
and B10.K(69NX)-H-4a
H1
b
possess nonon-H-1 histocompatibility differences from the G57BL/10 background. 相似文献
152.
Methanosarcina barkeri (strain MS) grew and converted acetate to CO2 and methane after an adaption period of 20 days. Growth and metabolism were rapid with gas production being comparable to that of cells grown on H2 and CO2. After an intermediary growth cycle under a H2 and CO2 atmosphere acetateadapted cells were capable of growth on acetate with formation of methane and CO2. When acetate-adapted Methanosarcina barkeri was co-cultered with Acetobacterium woodii on fructose or glucose as substrate, a complete conversion of the carbohydrate to gases (CO2 and CH4) was observed.Abbreviation CMC
carboxymethyl cellulose 相似文献
153.
Albert J. Banes Paul H. Bernstein Ralph E. Smith Gerald L. Mechanic 《Biochemical and biophysical research communications》1978,81(4):1390-1397
The patterns of [3H]-NaBH4-reduced bone collagen cross-links from osteopetrotic chickens were compared with those of age-matched controls. Ratios of the reduced cross-links, dihydroxylysinonorleucine (DHLNL)1 to hydroxylysinonorleucine (HLNL), were dramatically increased in tibia bone samples from osteopetrotic birds compared to values from control birds. In addition, the initial HLNL peak from osteopetrotic bone collagen was heterogeneous, whereas DHLNL from osteopetrotic or normal bone collagen and HLNL from normal bone collagen were homogeneous. 相似文献
154.
Alcohol Dehydrogenase Activities of Wine Yeasts in Relation to Higher Alcohol Formation 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Alcohol dehydrogenase activities were examined in cell-free extracts of 10 representative wine yeast strains having various productivities of higher alcohols (fusel oil). The amount of fusel alcohols (n-propanol, isobutanol, active pentanol, and isopentanol) produced by the different yeasts and the specific alcohol dehydrogenase activities with the corresponding alcohols as substrates were found to be significantly related. No such relationship was found for ethanol. The amounts of higher alcohols formed during vinification could be predicted from the specific activities of the alcohol dehydrogenases with high accuracy. The results suggest a close relationship between the control of the activities of alcohol dehydrogenase and the formation of fusel oil alcohols. Also, new procedures for the prediction of higher alcohol formation during alcoholic beverage fermentation are suggested. 相似文献
155.
Search for structural variants of three globin chains (x, y, z), synthesized only during mouse embryonic hematopoiesis, was carried out by electrophoretic analysis of blood from 12-day embryos, all with C57BL/6 mothers, and fathers from 115 inbred stocks selected for their diverse genetic origins. Structure of the -chains of adult hemoglobins differed among the tested strains, with 57 carrying the Hbb
sallele, 56 the Hbb
dallele, and two the Hbb
pallele. The search revealed no x- or z-chain variants but confirmed and extended knowledge of a previously described y-chain variant. Blood of all embryos sired by males from the 57 Hbb
sstrains contained only y1-chains, while blood of all embryos sired by Hbb
dor Hbb
pmales contained y2-chains as well as the y1-chains inherited from their C57 BL/6 mother. The locus controlling structure of the y-chain of mouse embryonic hemoglobins is thus extremely closely linked to the locus controlling structure of adult hemoglobin -chain, with maximum possible recombination frequency less than 0.019.This work was supported in part by Grants CA-01074 from the National Cancer Institute, USPHS, and GM 18684 from the National Institute of General Medical Sciences, in part by Grant ACS-VC58 from The American Cancer Society, in part by grants to the Jackson Laboratory from the Bushrod H. Campbell and Adah F. Hall Charity Fund and the Robert Sterling Clark Foundation, and in part by the Jackson Laboratory Endowment Fund. The Jackson Laboratory is fully accredited by the American Association for Accreditation of Laboratory Animal Care. 相似文献
156.
Roman Maksymowych Robert E. Cordero Ralph O. Erickson 《American journal of botany》1976,63(8):1047-1053
One application of gibberellic acid (GA3) to Xanthium shoots resulted in an initial large stimulation, followed by inhibition, of internode elongation. After presumed translocation of the hormone from the locus of its application to the stem apex several morphological changes were observed. There was a significant increase in number of mitotic figures in the apical meristem and a twofold increase in volume of the apical dome. With time, the rate of leaf production was accelerated about 1.8 times. The phyllotaxis of leaf primordia initiated under the influence of GA:, changed from a (2, 3) contact parastichy pattern in control shoot to a (3, 5) pattern. Final petiole length was smaller than the control, and the absolute rate of lamina expansion decreased under prolonged treatment. Gibberellic acid had a pronounced effect on leaf morphology. GAa induced the development of lanceolate leaves instead of typical deltoid leaves. The reduction in leaf area coincided with a 32% reduction in the average area of epidermal cells. Plastochron changes were correlated with anatomical and morphological changes during the course of leaf development. 相似文献
157.
158.
Three mutants selected from a population of sugarcane clone H54-775 that had been irradiated with 3 kR gamma-radiation all lacked toxin-binding protein activity. This activity previously had been shown to be essential for eye spot disease susceptibility and was demonstrated in the susceptible parent clone H54-775. In one mutant, the biochemical, immunochemical, and electrophoretic mobilities of the toxin-binding protein were all modified. 相似文献
159.
160.
Powdery mildew is a common and widespread plant disease of considerable agronomic relevance. It is caused by obligate biotrophic fungal pathogens which, in most cases, epiphytically colonize aboveground plant tissues. The disease has been typically studied as a binary interaction of the fungal pathogen with its plant hosts, neglecting, for the most part, the mutual interplay with the wealth of other microorganisms residing in the phyllo- and/or rhizosphere and roots. However, the establishment of powdery mildew disease can be impacted by the presence/absence of host-associated microbiota (epi- and endophytes) and, conversely, plant colonization by powdery mildew fungi might disturb indigenous microbial community structures. In addition, other (foliar) phytopathogens could interact with powdery mildews, and mycoparasites may affect the outcome of plant–powdery mildew interactions. In this review, we discuss the current knowledge regarding the intricate and multifaceted interplay of powdery mildew fungi, host plants and other microorganisms, and outline current gaps in our knowledge, thereby setting the basis for potential future research directions. 相似文献