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1.
Inhibitory diffusible factor IDF45, a G1 phase inhibitor 总被引:1,自引:0,他引:1
An inhibitory diffusible factor of 45 kDa (IDF45) was isolated from medium conditioned by dense cultures of 3T3 cells. The procedure involved Bio-Gel P150 chromatography and 2 reverse-phase FPLC. After the final step of purification, 60 ng/ml of IDF45 inhibited 50% of alpha-globulin-stimulated DNA synthesis. It was shown that IDF45 acted in the G1 phase of the cell cycle. When added for 8 h in the G1 phase of the cell cycle, it was able to inhibit DNA synthesis in the S phase which followed this G1 phase. Furthermore, IDF45 inhibited the early stimulation of RNA synthesis induced by alpha-globulin. 相似文献
2.
Aneta Ivanova Margarita Velcheva Plamen Denchev Atanas Atanassov Henri A. Van Onckelen 《Physiologia plantarum》1994,92(1):85-89
Endogenous indole-3-acetic acid, abscisic acid and cytokinins (zeatin, zeatin riboside, N-isopentenyladenine and N-isopentenyladenosine) were evaluated in initial explants (leaves) of in vitro propagated plants of alfalfa ( Medicago falcata L.) lines varying in embryogenic capacity and during the somatic embryogenesis process. Fast embryo-genic induction was correlated with high IAA and low ABA levels in the initial explants. No significant differences were observed in the cytokinin contents. Our results suggest that a certain hormone balance is necessary to allow the expression of the embryogenic potential. The consistent stages of the direct somatic embryogenesis are also characterized by changes in hormonal levels. 相似文献
3.
Aneta Kostadinova 《Systematic parasitology》1993,26(1):45-51
The chaetotaxy of Codonocephalus urniger (Rudolphi, 1819) cercariae recovered from Lymnaea palustris in a brackish water lake in Bulgaria is described and figured. Comparisons with Diplostomum spathaceum (Rudolphi, 1819) and D. pseudospathaceum Niewiadomska, 1984 cercariae indicate a similar general pattern in the distribution of sensilla but with marked differences in their number and arrangement on the ventral sucker, tail stem and furcae. Data on the chaetotaxy of other diplostomid species are used to reveal the similarities and variations in some complexes within the members of Diplostomidae with known cercarial chaetotaxy. 相似文献
4.
Tar-dependent and -independent pattern formation by Salmonella typhimurium. 总被引:1,自引:0,他引:1 下载免费PDF全文
When Salmonella typhimurium cells were allowed to swarm on either a minimal or complex semisolid medium, patterns of cell aggregates were formed (depending on the thickness of the medium). No patterns were observed with nonchemotactic mutants. The patterns in a minimal medium were not formed by a mutant in the aspartate receptor for chemotaxis (Tar) or by wild-type cells in the presence of alpha-methyl-D,L-aspartate (an aspartate analog), thus resembling the patterns observed earlier in Escherichia coli (E. O. Budrene and H. C. Berg, Nature [London] 349:630-633, 1991) and S. typhimurium (E. O. Budrene and H. C. Berg, Abstracts of Conference II on Bacterial Locomotion and Signal Transduction, 1993). Distinctively, the patterns in a complex medium had a different morphology and, more importantly, were Tar independent. Furthermore, mutations in any one of the genes encoding the methyl-accepting chemotaxis receptors (tsr, tar, trg, or tcp) did not prevent the pattern formation. Addition of saturating concentrations of the ligands of these receptors to wild-type cells did not prevent the pattern formation as well. A tar tsr tcp triple mutant also formed the patterns. Similar results (no negative effect on pattern formation) were obtained with a ptsI mutant (defective in chemotaxis mediated by the phosphoenolpyruvate-dependent carbohydrate:phosphotransferase system [PTS]) and with addition of mannitol (a PTS ligand) to wild-type cells. It therefore appears that at least two different pathways are involved in the patterns formed by S. typhimurium: Tar dependent and Tar independent. Like the Tar-dependent patterns observed by Budrene and Berg, the Tar-independent patterns could be triggered by H(2)O(2), suggesting that both pathways of pattern formation may be triggered by oxidative stress. 相似文献
5.
Effect of transformation of chicken cells by Rous sarcoma virus on in vitro phosphorylation of nuclear non-histone proteins 总被引:1,自引:0,他引:1
Mouse macrophages were treated with 42 different glycans in vitro. Macrophages were stimulated—as judged by morphology, cell size, 5′-nucleotidase activity and the incorporation of [14C]glucosamine by some insoluble glycans, e.g. yeast glucan. Not all insoluble glycans were stimulatory (e.g. chitin). Laminaran, with a monosaccharide content and bonding pattern similar to that of yeast glucan, could be rendered stimulatory by cross-linking and insolubilization. There was a clear correlation between stimulatory effect and the ability to convert complement factor C3. Preincubation of sera with yeast—presumably producing complement cleavage products—potentiated the stimulatory effect of yeast glucan. It is suggested that endocytosis of glycans with subsequent intracellular triggering of a complement reaction is the underlying mechanism of glycan stimulation. 相似文献
6.
Mycopathologia - Dermatophytosis is a widespread disease with high prevalence and a substantial economic burden associated with costs of treatment. The pattern of this infectious disease covers a... 相似文献
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Maciej K. Konopiński Antoni Amirowicz Petr Kotlík Krzysztof Kuku?a Aneta Bylak Ladislav Pekarik Alena ?ediva 《PloS one》2013,8(12)
As a result of specific adaptations and habitat preferences strongly rheophilic fish species may show high levels of endemism. Many temperate rheophilic fish species were subjected to a series of range contractions during the Pleistocene, and then successfully expanded during the Holocene, colonising previously abandoned areas. The Carpathian barbel (Barbus carpathicus Kotlík, Tsigenopoulos, Ráb et Berrebi 2002) occurs in the montane streams in three basins of the main Central European rivers in the northern part of the Carpathian range. We used genetic variation within 3 mitochondrial and 9 microsatellite loci to determine a pattern of postglacial expansion in B. carpathicus. We found that overall genetic variation within the species is relatively low. Estimate of time to the most recent common ancestor (tMRCA) of mitochondrial sequences falls within the Holocene. The highest levels of genetic variation found in upper reaches of the Tisa river in the Danube basin suggest that glacial refugia were located in the south-eastern part of the species range. Our data suggest that the species crossed different watersheds at least six times as three genetically distinct groups (probably established in different expansion episodes) were found in northern part of the species range. Clines of genetic variation were observed in both the Danube and Vistula basins, which probably resulted from subsequent bottlenecks while colonizing successive habitats (south eastern populations) or due to the admixture of genetically diverse individuals to a previously uniform population (Vistula basin). Therefore, B. carpathicus underwent both demographic breakdowns and expansions during the Holocene, showing its distribution and demography are sensitive to environmental change. Our findings are important in the light of the current human-induced habitats alterations. 相似文献