全文获取类型
收费全文 | 3046篇 |
免费 | 245篇 |
国内免费 | 2篇 |
出版年
2021年 | 32篇 |
2020年 | 20篇 |
2018年 | 25篇 |
2017年 | 25篇 |
2016年 | 61篇 |
2015年 | 84篇 |
2014年 | 98篇 |
2013年 | 143篇 |
2012年 | 139篇 |
2011年 | 148篇 |
2010年 | 114篇 |
2009年 | 111篇 |
2008年 | 142篇 |
2007年 | 145篇 |
2006年 | 129篇 |
2005年 | 114篇 |
2004年 | 130篇 |
2003年 | 110篇 |
2002年 | 139篇 |
2001年 | 65篇 |
2000年 | 67篇 |
1999年 | 47篇 |
1998年 | 48篇 |
1997年 | 40篇 |
1996年 | 33篇 |
1995年 | 38篇 |
1994年 | 31篇 |
1993年 | 25篇 |
1992年 | 33篇 |
1991年 | 28篇 |
1990年 | 36篇 |
1989年 | 39篇 |
1988年 | 33篇 |
1987年 | 24篇 |
1986年 | 16篇 |
1985年 | 26篇 |
1984年 | 31篇 |
1983年 | 17篇 |
1982年 | 28篇 |
1981年 | 32篇 |
1980年 | 15篇 |
1979年 | 19篇 |
1978年 | 17篇 |
1977年 | 26篇 |
1976年 | 23篇 |
1973年 | 18篇 |
1971年 | 15篇 |
1968年 | 15篇 |
1963年 | 15篇 |
1960年 | 16篇 |
排序方式: 共有3293条查询结果,搜索用时 15 毫秒
11.
12.
Regeneration of transgenic plants of Prunus armeniaca containing the coat protein gene of Plum Pox Virus 总被引:1,自引:0,他引:1
Margit Laimer da Câmara Machado Artur da Câmara Machado Veronika Hanzer Hans Weiss Ferdinand Regner Herta Steinkellner Diethard Mattanovich Regina Plail Elisabeth Knapp Birgit Kalthoff Hermann Katinger 《Plant cell reports》1992,11(1):25-29
Summary A system was developed which allows the transfer of foreign genes into apricot cultivars. We report the transformation and regeneration of Prunus armeniaca plants with Agrobacterium tumefaciens strain LBA 4404 containing various binary plasmids, pBinGUSint, carrying the marker gene ß-glucuronidase (GUS) and pBinPPVm, carrying the coat protein gene of Plum Pox Virus (PPV). The marker gene GUS was used for optical evaluation of the efficiency of the transformation system. The coat protein gene of PPV was used to introduce coat protein mediated resistance against one of the most important pathogens of stone fruit trees in Europe and the whole Mediterranean area. This is the first report of the successful integration of a viral coat protein gene into a fruit tree species, opening a new perspective on the control of the disease.Abbreviations GUS
ß-glucuronidase
- PPV
Plum Pox Virus
- BA
6-benzylaminopurine
- NPTII
neomycin phosphotransferase II
- CP
coat protein
- CaMV
Cauliflower Mosaic Virus
- P35S 35S
promoter
- MS
Murashige and Skoog
- PCR
polymerase chain reaction
- P/C/I
phenol/chloroform/isoamylalcohol
- RNase
ribonuclease
- dNTP
deoxyribonucleosidetriphosphate
- DMSO
dimethyl sulfoxide 相似文献
13.
Embryogenic suspension cultures of Abies alba were established using an embryogenic suspensor mass culture originating from the zygotic embryo in immature seed explants (Schuller et al. 1989). Protoplasts were isolated from the suspension material. The protoplasts were immobilized in alginate layers in order to follow the development of single protoplasts. During the first days of protoplast culture a modified Kao and Michayluk (1975) medium proved to be necessary for subsequent divisions. The formation of proembryos succeeded within 2–3 weeks when subcultured with a modified Schenk and Hildebrandt (1972) liquid medium. Light, enhanced sugar concentration, and the addition of abscisic acid led to the formation of slightly green torpedo-shaped somatic embryos after 6–8 weeks from protoplast isolation.Abbreviations ABA
abscisic acid
- BAP
N6-benzyladenine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- ESM
Embryonal suspensor mass (Gupta and Durzan 1986)
- KM
Kao and Michayluk (1975)
- LP
(von Arnold and Eriksson 1977)
- MES
2-(N-morpholino)ethane-sulfonic acid
- NAA
1-naphthalene-acetic acid (sodium salt)
- PVP
polyvinylpyrrolidone
- SH
Schenk and Hildebrandt (1972)
- Tween 80
polyoxyethylene-sorbitan-monooleate 相似文献
14.
15.
16.
Improved Agar Bottle Plate for Isolation of Methanogens or Other Anaerobes in a Defined Gas Atmosphere 总被引:7,自引:4,他引:3 下载免费PDF全文
A bottle plate for the cultivation of methanogens or other organisms in a defined pressurized-gas atmosphere was developed. The bottle provides the convenience of an agar streak plate, solves the problem of the water exudate from agar medium, and provides a convenient way of adding or sampling a defined gas atmosphere. 相似文献
17.
Summary With the aim of comparing the primary structures of gene products coded for by T-even bacteriophages we constructed clone libraries of the DNAs of bacteriophages T2 and T6. Using hybrid M13 phages carrying the gene for the T4-coded -glucosyl transferase (gt) we isolated corresponding T2 and T6 clones. The nucleotide sequences of the three gt genes and the amino acid sequences derived were compared. The differences between the genes and their products are discussed in terms of structure, function and evolutionary aspects.Abbreviations bp
base pair
- gt
glucosyl transferase
- HMC
5-hydroxymethyl cytosine
- orf
open reading frame
- Xgal
5-bromo-4-chloro-3-indolyl--d-galactoside 相似文献
18.
Isolation and characterization of butanol-resistant mutants of Clostridium acetobutylicum. 总被引:2,自引:1,他引:1 下载免费PDF全文
M Hermann F Fayolle R Marchal L Podvin M Sebald J P Vandecasteele 《Applied microbiology》1985,50(5):1238-1243
In a wild-type strain of Clostridium acetobutylicum isolated from soil, solvent production appeared limited by butanol toxicity. Butanol-resistant mutants have been obtained which produced significantly higher solvent concentrations (about 30%) than the wild-type strain. Some other physiological differences were observed between a selected resistant mutant and the wild-type strain at the level of solvent resistance and sporulation. 相似文献
19.
Cytochemical study of macrophage lysosomal inorganic trimetaphosphatase and acid phosphatase 总被引:2,自引:0,他引:2
Cytochemical investigations have associated acid inorganic trimetaphosphatase (TMPase) activity with the lysosomes of certain cell types. We have used the modified staining technique of Berg to show that this enzyme activity is present in normal mononuclear phagocytes and macrophage cell lines. We have found this enzyme activity to be present in murine RAW264 macrophages, in human U937 macrophages, in normal human blood monocytes, and in guinea pig peritoneal macrophages. All of the RAW264 and U937 macrophages showed intense TMPase activity. Many of the human monocytes and most of the guinea pig macrophages were labeled by this method. The reaction product was associated with the lysosomes of these cell types. The lysosomal staining-pattern was similar to that of acid phosphatase. Differences with regard to Golgi staining were noted. This indicates that TMPase is a lysosomal enzyme of mammalian macrophages. The distinction between TMPase and acid phosphatase activity has been demonstrated by measuring the pH optimum of each enzyme. Using substrates identical to those of the ultrastructural cytochemistry, we show that the pH optimum of TMPase is 4.0 and that of acid phosphatase is 5.0. The enzymatic activities are therefore ultrastructurally and biochemically distinct. Following phagocytosis of latex, yeast (Saccharomyces cerevisiae), or Corynebacterium parvum, TMPase has been found to be associated with phagosomes. This enzyme may take part in the degradation of phagocytosed materials, particularly microorganisms which contain inorganic polyphosphates and metaphosphates. 相似文献
20.
Stephanie Bringer-Meyer Marc Scollar Hermann Sahm 《Applied microbiology and biotechnology》1985,23(2):134-139
Summary A mutant ofZymomonas mobilis deficient in the utilization of fructose for growth and ethanol formation was shown to lack fructokinase activity. When grown in media which contained glucose+fructose or sucrose, both the mutant and wild type produced sorbitol in amounts up to 60 g·l-1, depending on the initial concentrations of sugars. Sorbitol formation was accompanied by an accumulation of acetaldehyde, gluconate, and acetoin. A ferricyanide-dependent sorbitol dehydrogenase could be localized in the cell membrane; it thus resembles the sorbitol dehydrogenase ofGluconobacter suboxydans. Neither a NAD(P)H dependent reduction of fructose nor a NAD(P) dependent dehydrogenation of sorbitol could be detected in cell-free extracts. The use of fructose-negative mutants ofZ. mobilis for the enrichment of fructose in glucose+fructose mixtures is discussed. 相似文献