全文获取类型
收费全文 | 297篇 |
免费 | 15篇 |
出版年
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 8篇 |
2012年 | 19篇 |
2011年 | 24篇 |
2010年 | 14篇 |
2009年 | 5篇 |
2008年 | 20篇 |
2007年 | 33篇 |
2006年 | 11篇 |
2005年 | 16篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有312条查询结果,搜索用时 15 毫秒
61.
Matthew C. P. Glyn Michaela Egertová Blanka Gazdova Aleš Kovarik Milan Bezdek Andrew R. Leitch 《Chromosoma》1997,106(8):485-492
This paper describes the effects of 5-azacytidine on the condensation state of rye (Secale cereale L.) chromatin introduced into the wheat genome (Triticum aestivum L. cv. Beaver). The wheat cultivar Beaver carries a translocation between the short arm of rye chromosome 1R (1RS) and the
long arm of wheat chromosome 1B (1BL/1RS). 1RS can be detected using genomic in situ hybridisation and carries a ribosomal
DNA (rDNA) locus that can be simultaneously detected using multiple labelling strategies. The rDNA locus divides 1RS into
a distal region that is gene rich and a proximal region that is gene poor and highly methylated. 1RS also carries a large
block of subtelomeric heterochromatin. The drug, which acts to inhibit DNA methylation in plants, has three pronounced effects
on interphase nuclei. (1) It induces aberrant condensation of the rye subtelomeric heterochromatin and in many cases induces
sister chromatid separation in the subtelomeric heterochromatin of G2 nuclei. (2) Nuclei trisomic for 1RS are observed at
low frequency in treated material and are probably a consequence of aberrant sister chromatid separation or condensation.
(3) The drug alters normal condensation of 1RS euchromatin. However, contrary to expectation the effect is not simply to induce
decondensation. The proximal region of the arm actually condenses at low levels of drug administration while the distal region
remains unaltered or increases its decondensation state. Increasing the concentration of 5-azacytidine induces a biphasic
response and at the highest concentration used all regions of the arm show signs of decondensation. Thus the influence of
the drug on chromatin condensation depends on the genomic structure.
Received: 14 July 1997; in revised form: 26 August 1997 / Accepted: 27 August 1997 相似文献
62.
Zdeněk Wimmer Richard Tykva Blanka Bennettová Věra Vlasáková Tomáš Elbert 《Invertebrate neuroscience : IN》1997,3(2-3):193-197
A synthetic insect juvenile hormone analog (a juvenoid), ethylN-[2-[4-[[2,2-(ethylenedioxy)cyclohexyl]methyl]phenox]ethyl]carbamate, which has displayed high biological activity against
different insect species and high stability under field conditions, was selected as a biologically active model compound for
a study of a juvenile hormone analog degradation. The biologically active compound itself and its three diversely radiolabeled
derivatives were applied to the flesh fly (Sarcophaga bullata) or the tsetse fly (Glossina palpalis), respectively. Monitoring of a fate of the applied juvenile hormone analog was carried out using a detection method of the
radioactivity microdistribution within the whole insect body in combination with a radio high performance liquid chromatography
(radio-HPLC), both of whole-body extracts made in different, but in advance scheduled, time intervals, and of extracts of
insect excreta accumulated over an eight-day experiment. 相似文献
63.
Conservation tool or threatening process? management implications of interactions of cattle with vegetation and land at the Vale of Belvoir reserve
下载免费PDF全文
![点击此处可从《Ecological Management & Restoration》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Blanka Tengia Matthew Taylor Jamie Kirkpatrick 《Ecological Management & Restoration》2016,17(2):147-151
A recently purchased private reserve of high conservation value has been grazed in summer by cattle since the early nineteenth century. We ask whether the cattle are causing continuing damage and whether they are necessary to maintain any conservation values. We used five‐year‐old exclosures to determine the effects of cattle on wetland vegetation, mapped damage to soils and landforms and mapped cattle dung deposition in relation to the distributions of rare and threatened plant species. Cattle impacts on wetland plants were minor. Cattle damage to landforms by pugging and bank collapse was frequent near unfenced water bodies. Rare and threatened species were largely on well‐drained ground, while cattle dung was concentrated in wetlands and near water bodies. We conclude that cattle grazing is impacting some conservation values and is not necessary for conservation purposes. Destocking should be accompanied by careful monitoring of threatened plant populations. If necessary, alternative planned disturbances can provide regeneration niches for rare and threatened plants. 相似文献
64.
Status of Savi's pipistrelle Hypsugo savii (Chiroptera) and range expansion in Central and south‐eastern Europe: a review
下载免费PDF全文
![点击此处可从《Mammal Review》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Marcel Uhrin Ulrich Hüttmeir Marina Kipson Péter Estók Konrad Sachanowicz Szilárd Bücs Branko Karapandža Milan Paunović Primož Presetnik Andriy‐Taras Bashta Edita Maxinová Blanka Lehotská Roman Lehotský Levente Barti István Csösz Farkas Szodoray‐Paradi Imre Dombi Tamás Görföl Sándor A. Boldogh Csaba Jére Irina Pocora Petr Benda 《Mammal Review》2016,46(1):1-16
- 相似文献
65.
Characterization of Infectious Deoxyribonucleic Acid from Temperate Bacillus subtilis Bacteriophage φ 105
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Phenol-extracted, infectious deoxyribonucleic acid (DNA) species from phi105 phage particles, from phi105 lysogenic bacteria, and from induced phi105 lysogenic bacteria were sedimented in sucrose gradients. Infectious DNA from phi105 particles sedimented like the bulk of mature phage DNA in neutral sucrose. Infectivity of prophage DNA was associated with fast-sedimenting material of heterogenous size. Infectious vegetative phage DNA sedimented somewhat faster than mature phage DNA; it was rapidly converted to a poorly infectious form during the infection. 相似文献
66.
Callogenesis was induced in mature embryos. The efficiency of induction and the growth of calli were dependent on 2,4-D concentration. No regeneration of buds or shoots was observed in 720 calli studied, but most calli showed intensive root proliferation on the regeneration medium. Most of the root meristem cells maintained diploid chromosome number. Only a low proportion (about 3.5%) of tetraploid cells was found. No other chromosomal changes were observed. Chromosomal variability does not contribute to the inability of calli derived from mature barley embryos to form buds and shoots. 相似文献
67.
68.
Study of the carbohydrate part of yeast acid phosphatase 总被引:2,自引:0,他引:2
Branko Kozulić Slobodan Barbarić Blanka Ries Pavao Mildner 《Biochemical and biophysical research communications》1984,122(3):1083-1090
It has been found that the carbohydrate part of acid phosphatase from yeast Saccharomyces cerevisiae consists of 16 N-glycosidically linked carbohydrate chains containing from 14 to about 150 mannose units. The presence of very small amounts of O-glycosidically linked chains was indicated. Acetolysis studies pointed to a high similarity in the structure of acid phosphatase and mannan carbohydrate chains. A new method is described for cross-linking of acid phosphatase specifically via carbohydrate chains. The possibility to cross-link the enzyme subunits intramolecularly is in accordance with the suggestion that carbohydrate chains play a role in subunit associations. 相似文献
69.
Blanka Úlehlová 《Folia Geobotanica》1990,25(3):303-308
Changes in chemical composition of autochthonous plant litter undergoing decomposition in litter mesh-bags exposed in a transect across four vegetational zones of a fishpond littoral were estimated during the spring, summer and winter season. The highest decomposition rate was found in all four zones in spring, the lowest one in winter. The decomposition was faster in the two aquatic than in the two terrestrial zones in the spring and the summer season. The litter was enriched with nitrogen and released potassium in all locelities and seasons. The uptake or release of other mineral constituents appeared to be specific for each zone and to depend on the season of the year. 相似文献
70.
Peritoneal exudate cells (PEC) and peripheral blood leukocytes (PBL) are most frequently used in the migration inhibition test. The aim o this work was to compare the ability of these two types of cells to reflect tuberculin hypersensitivity in the migration inhibition test. We sensitized 36 guinea pigs with complete Freund's adjuvant and 20 controls were injected with incomplete Freund's adjuvant. Migration of PEC in medium containing 5, 15, or 75 μg of PPD/ml was assessed after 30 min, and 1, 2, 4, 18, 24, and 48 hr of incubation. The migration of PEC from sensitized animals was inhibited, the inhibition being dose dependent and, with lower concentrations of the antigen, becoming significant only after 4 hr or later. With both PEC and PBL from the same sensitized animal we observed virtually identical migration inhibition in the presence of 75 μg of PPD/ml. A correlation was found between the migration inhibition indices of PEC and PBL. In the indirect test, active supernatants containing lymphokines caused nearly identical migration inhibition of PEC and PBL from normal animals. It follows that in the guinea pig PEC and PBL behave alike both in the direct and in the indirect migration inhibition tests. Thus, PEC and PBL appear to be equally valuable sources of cells for migration inhibition tests. 相似文献