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131.
Diversification and speciation processes are influenced by intrinsic (ecological specialization, dispersal) and extrinsic
(habitat structure and instability) factors, but the effect of ecological characteristics on dispersal is difficult to assess.
This study uses mitochondrial control region sequences to investigate the population structure and demographic history of
the endemic Lake Tanganyika cichlid Neolamprologus caudopunctatus with a preference for the rock-sand interface along two stretches of continuous, rocky shoreline, and across a sandy bay
representing a potential dispersal barrier. Populations along uninterrupted habitat were not differentiated; whereas, the
sandy bay separated two reciprocally monophyletic clades. The split between the two clades between 170,000 and 260,000 years
BP coincides with a period of rising water level following a major lowstand, and indicates that clades remained isolated throughout
subsequent lake level fluctuations. Low long-term effective population sizes were inferred from modest genetic diversity estimates,
and may be due to recent population expansions starting from small population sizes 45,000–60,000 years BP. Comparisons with
available data from specialized rock-dwelling species of the␣same area suggest that habitat structure and lake level fluctuations
determine phylogeographic patterns on large scales, while fine-scale population structure and demography are modulated by
species-specific ecologies. 相似文献
132.
Alex Whittle Robert L. Barnett Dan J. Charman Angela V. Gallego-Sala 《Ecology letters》2022,25(1):17-25
The salinisation of many coastal ecosystems is underway and is expected to continue into the future because of sea-level rise and storm intensification brought about by the changing climate. However, the response of soil microbes to increasing salinity conditions within coastal environments is poorly understood, despite their importance for nutrient cascading, carbon sequestration and wider ecosystem functioning. Here, we demonstrate deterioration in the productivity of a top-tier microbial group (testate amoebae) with increasing coastal salinity, which we show to be consistent across phylogenetic groups, salinity gradients, environment types and latitude. Our results show that microbial changes occur in the very early stages of marine inundation, presaging more radical changes in soil and ecosystem function and providing an early warning of coastal salinisation that could be used to improve coastal planning and adaptation. 相似文献
133.
Konstanze T. Schiessl Adin Ross‐Gillespie Daniel M. Cornforth Michael Weigert Colette Bigosch Sam P. Brown Martin Ackermann Rolf Kümmerli 《Evolution; international journal of organic evolution》2019,73(4):675-688
How unicellular organisms optimize the production of compounds is a fundamental biological question. While it is typically thought that production is optimized at the individual‐cell level, secreted compounds could also allow for optimization at the group level, leading to a division of labor where a subset of cells produces and shares the compound with everyone. Using mathematical modeling, we show that the evolution of such division of labor depends on the cost function of compound production. Specifically, for any trait with saturating benefits, linear costs promote the evolution of uniform production levels across cells. Conversely, production costs that diminish with higher output levels favor the evolution of specialization–especially when compound shareability is high. When experimentally testing these predictions with pyoverdine, a secreted iron‐scavenging compound produced by Pseudomonas aeruginosa, we found linear costs and, consistent with our model, detected uniform pyoverdine production levels across cells. We conclude that for shared compounds with saturating benefits, the evolution of division of labor is facilitated by a diminishing cost function. More generally, we note that shifts in the level of selection from individuals to groups do not solely require cooperation, but critically depend on mechanistic factors, including the distribution of compound synthesis costs. 相似文献
134.
Xiaojuan Liu Zhongyan Huan Qingfang Zhang Mingqi Zhong Weizhou Chen Muhammad Aslam Hong Du 《Journal of phycology》2019,55(5):1059-1070
This study aimed to address the importance of glutamine synthetase II (GSII) during nitrogen assimilation in macroalga Gracilariopsis lemaneiformis. The cDNA full‐length sequence of the three glGSII genes was revealed to have the 5′ m7G cap, 5′‐untranslated region, open reading frame (ORF), 3′‐untranslated region, and a 3′ poly (A) tail. The three glGSIIs were classified into plastid glGS2 and cytosolic glGS1‐1 and glGS1‐2, having conserved GSII domains but different cDNA sequences. The complicated 5′ end flanking region indicates complex function of glGS genes. glGS1 genes were significantly up‐regulated under the different NH4+: NO3? ratio (i.e., 40:10, 25:25, 10:40, and 0:50) except glGS2 which dramatically up‐regulated under the low NH4+: NO3? ratio (i.e., 10:40 and 0:50) during different cultivation times. These different expression patterns perhaps are due to the different biological roles of GS1 and GS2 in the gene family. Furthermore, hypothetical working model of nitrogen assimilation pathway exhibiting the role of glGS1 and glGS2 is proposed. Finally, glGS2 was expressed in Escherichia coli BL21 (DE3), and the optimal conditions for culture (15°C, overnight), purification (500 mM imidazole washing), and activity (pH 7.4, 37°C) were established. This study lays a very important foundation for exploring the role of GS in nitrogen assimilation in algae and plants. 相似文献
135.
《L'Anthropologie》2019,123(2):403-422
The Upper Palaeolithic site of Yudinovo is one of the reference sites, located in the Desna River Basin. Multidisciplinary field studies, organized by the Desna mission (MAE RAS) and conducted between 2004 and 2016, have changed the vision existed so far on the structure and character of the Yudinovo site as well as on the duration of its occupations. The researchers found an ancient ford used by mammoths and other big mammals to cross the river, and a water source was one of the main factors in explaining the location of the Yudinovo site. The site has been occupied in a cyclical way for stays of varied duration. It was frequented by Prehistoric Men during the different seasons, and periods of occupation were apparently of different duration. The stratigraphy of the Yudinovo site reveals two major episodes in the evolution of the site. The dating of the lower archaeological layer dates back to 15,000–13,500 BC. J.C., while the upper layer is attributed to the period of 12,500–12,000 BC. The lower layer, which was formed during the major episode of occupation of the site, is rather thin and shows the complex stratigraphic structure. Various areas of activities, evacuation structures, storage areas with mammoth bones are discovered. Some elements of the lower archaeological layer are perfectly correlated with different episodes of sporadic occupation. 相似文献
136.
Aki Tomizawa Kazuhiro Nogawa Yuuka Watanabe Mitsuhiro Oishi Kumihiko Tanaka Kouichi Sakata 《Chronobiology international》2019,36(6):751-757
We investigated how differences in circadian rhythm type affect the health of workers engaged in shift work. Employees, who were newly hired in a steel company between 2007 and 2011, received the Morningness–Eveningness Questionnaire (MEQ) survey. The target participants were 153 male shift workers who were not being treated with any antihyperlipidemic drugs and underwent periodic physical examinations including blood tests at least twice. According to the score of the MEQ at the time of joining the company, we classified the subjects into five types. Longitudinal changes in serum lipid level were estimated among the circadian rhythm types adjusted for age, BMI, and other covariates using a linear mixed model. The regression coefficient of total cholesterol level in the “definitely and moderately morning” group was ?17.83 (95% confidence interval (CI): ?33.42 to ?2.23), and in the “intermediate ‘group’ was ?16.84 [95% CI: ?30.40 to ?3.28], compared to the moderate evening type.” The total cholesterol level was higher in the moderately evening type than in any of the other groups. Between the Morningness–Eveningness (ME) type and Low-density lipoprotein (LDL) cholesterol levels, compared with the “moderately evening type” group, the regression coefficient in the “intermediate type” group was ?16.08 (95% CI: ?28.79 to ?3.37), and in the “definitely and moderately morning type” group was ?17.50 [95% CI: ?32.11 to ?2.88]. The “moderately evening type” group had a higher LDL cholesterol level than any of the other groups. Evening-type circadian rhythm type shift workers are more prone to elevated serum lipid levels. 相似文献
137.
138.
探讨SHCBP1在乳腺癌及其不同亚型中的表达特征和预后价值。利用Oncomine, bc-GenExMiner v4.2, Kaplan-Meier plotter, GSE41994及STRING数据库分析乳腺癌病人SHCBP1的mRNA表达水平及其与乳腺癌患者生存率的相关性等。结果:(1)乳腺癌组织中SHCBP1的mRNA水平明显高于正常组织样本,但不同分子亚型的乳腺癌患者中SHCBP1的表达水平不同;(2)SHCBP1表达升高可导致Luminal A亚型更短的无转移生存期(Distant metastasis-free survival,DMFS)和无病生存期(Disease-free survival, DFS);(3)在雌激素受体阳性(ER+)、孕酮受体阳性(PR+)亚型、仅接受辅助化疗、仅接受辅助化疗的ER(+)与接受包括或排除内分泌治疗乳腺癌患者中,SHCBP1表达升高则无复发生存率(Relapse-free survival,RFS)显著缩短;(4)SHCBP1和CDC45 mRNA表达水平之间呈正相关,并可能与KIF23等10种蛋白相互作用。结论:SHCBP1是一种很有前景的乳腺癌预后指标和潜在的治疗靶点。 相似文献
139.
Flow cytometric analysis with 4,6-diamidino-2-phenylindole (DAPI) staining was used to screen for chromosomal changes in Quercus robur during in vitro culture. The initiated cell lines (1992 until 1999) were maintained via secondary embryogenesis on P24 medium with 0.9 M 6-benzylaminopurine (BAP) in regular subculture intervals of 6 weeks. Regenerated plants established in the greenhouse and in vitro plantlets derived from encapsulated somatic embryos were screened. The embryogenic cell lines were characterized as individual clones by isoenzyme analysis. Flow cytometric relative DNA content analysis of the first screening period revealed that somaclonal variation in form of tetraploidy occurred in two out of 26 tested somatic embryo clones (Alt and Jung). These two clones lost their ability to convert into plantlets. Intraspecific relative DNA content variation including technical variation was below 3 %. In the second screening period, however, 3 out of 37 clones (Alt, E4.31H9 and P3.27H) contained tetraploid cells leading to the assumption that the frequency of tetraploidy seems to be correlated with the duration of in vitro culture. No chromosomal differences were detected in regenerated plants. However, tetraploidy occurred in 8 % of the tested clones over a culture period of 7 years. 相似文献
140.
Remans Tony Schenk Peer M. Manners John M. Grof Christopher P.L. Elliott Adrian R. 《Plant Molecular Biology Reporter》1999,17(4):385-395
The Green Fluorescent Protein (GFP) from Aequorea victoria has begun to be used as a reporter protein in plants. It is particularly useful as GFP fluorescence can be detected in a non-destructive manner, whereas detection of enzyme-based reporters often requires destruction of the plant tissue. The use of GFP as a reporter enables transgenic plant tissues to be screened in vivo at any growth stage. Quantification of GFP in transgenic plant extracts will increase the utility of GFP as a reporter protein. We report herein the quantification of a mGFP5-ER variant in tobacco leaf extracts by UV excitation and a sGFP(S65T) variant in sugarcane leaf and callus extracts by blue light excitation using the BioRad VersaFluorTM Fluorometer System or the Labsystems Fluoroskan Ascent FL equipped with a narrow band emission filter (510 ± 5 nm). The GFP concentration in transgenic plant extracts was determined from a GFP-standard series prepared in untransformed plant extract with concentrations ranging from 0.1 to 4 g/ml of purified rGFP. Levels of sgfp(S65T) expression, driven by the maize ubiquitin promoter, in sugarcane calli and leaves ranged up to 0.525 g and 2.11 g sGFP(S65T) per mg of extractable protein respectively. In tobacco leaves the expression of mgfp5-ER, driven by the cauliflower mosaic virus (CaMV) 35S promoter, ranged up to 7.05 g mGFP5-ER per mg extractable protein. 相似文献