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991.
辣椒细胞质雄性不育花药败育及淀粉粒分布的细胞学观察 总被引:2,自引:0,他引:2
用PAS反应对辣椒细胞质雄性不育系8214A和保持系8214B花药中的淀粉粒分布进行研究.在减数分裂前,保持系花药与不育系花药的结构和淀粉粒分布相似.保持系花药减数分裂后,药壁绒毡层细胞开始液泡化并体积增大,在药隔薄壁细胞中积累了许多较小的淀粉粒;在小孢子晚期,绒毡层细胞退化,在药隔薄壁细胞中淀粉粒体积增大;在二胞花粉时期,随着花粉大液泡的消失花粉中出现淀粉粒;花粉成熟时,其细胞质中积累了丰富的淀粉粒.不育系花药减数分裂后,由于药室腔的空间不能扩大,四分体被挤压在一起,最终四分体小孢子败育.不育花药的维管组织发育正常,但较多的淀粉粒积累在药隔薄壁细胞中.该种辣椒雄性不育系中.花粉的败育发生在四分体时期.绒毡层细胞结构异常可能影响糖类物质向药室的正常转运.该种辣椒雄性不育系的绒毡层异常与花粉败育有关. 相似文献
992.
van Gassen KL Hessel EV Ramakers GM Notenboom RG Wolterink-Donselaar IG Brakkee JH Godschalk TC Qiao X Spruijt BM van Nieuwenhuizen O de Graan PN 《Genes, Brain & Behavior》2008,7(5):578-586
Febrile seizures (FS) are the most prevalent seizures in children. Although FS are largely benign, complex FS increase the risk to develop temporal lobe epilepsy (TLE). Studies in rat models for FS have provided information about functional changes in the hippocampus after complex FS. However, our knowledge about the genes and pathways involved in the causes and consequences of FS is still limited. To enable molecular, genetic and knockout studies, we developed and characterized an FS model in mice and used it as a phenotypic screen to analyze FS susceptibility. Hyperthermia was induced by warm air in 10- to 14-day-old mice and induced FS in all animals. Under the conditions used, seizure-induced behavior in mice and rats was similar. In adulthood, treated mice showed increased hippocampal Ih current and seizure susceptibility, characteristics also seen after FS in rats. Of the seven genetically diverse mouse strains screened for FS susceptibility, C57BL/6J mice were among the most susceptible, whereas A/J mice were among the most resistant. Strains genetically similar to C57BL/6J also showed a susceptible phenotype. Our phenotypic data suggest that complex genetics underlie FS susceptibility and show that the C57BL/6J strain is highly susceptible to FS. As this strain has been described as resistant to convulsants, our data indicate that susceptibility genes for FS and convulsants are distinct. Insight into the mechanisms underlying seizure susceptibility and FS may help to identify markers for the early diagnosis of children at risk for complex FS and TLE and may provide new leads for treatment. 相似文献
993.
994.
Background
Gliomas are the most common primary tumors in the central nervous system. Due to complicated signaling pathways involved in glioma progression, effective targets for treatment and biomarkers for prognosis prediction are still scant.Results
In this study we revealed that a new microRNA (miR), the miR-221, was highly expressed in the glioma cells, and suppression of miR-221 resulted in decreased cellular proliferation, migration, and invasion in glioma cells. Mechanistic experiments validated that miR-221 participates in regulating glioma cells proliferation and invasion via suppression of a direct target gene, the Semaphorin 3B (SEMA3B). The rescue experiment with miR-221 and SEMA3B both knockdown results in significant reversion of miR-221 induced phenotypes.Conclusion
Taken together, our findings highlight an unappreciated role for miR-221 and SEMA3B in glioma. 相似文献995.
基于前期高通量测序结果设计EST-SSR引物, 用于评估国内外不同生态区144份糜子(Panicum miliaceum)种质资源的遗传差异。结果表明, 200对引物中80对呈多态性, 开发效率为40%; 引物分辨率(Rp)为0.67-4.67 (平均值为2.00), 扩增产物大小为50-500 bp。144份材料在80个位点共检测到206个等位变异, 每个位点为2-3个; 多样性指数(I)为0.659 3 (RYW108)-1.087 2 (RYW124), 平均为0.859 9; 多态性信息含量(PIC)为0.222 9 (RYW98)-0.717 2 (RYW124), 平均为0.457 3。基于UPGMA将144份资源划分为3个群组, 其中2个群组主要为北方春糜子区材料, 另一个群组主要为黄土高原春夏糜子区材料。基于Structure (K=4)将材料划分为4个类群, 即2个代表北方资源基因库以及代表黄土高原和国外资源基因库各1个。基于主成分分析将材料聚为7个类群, 划分结果与材料的地理来源一致。 相似文献
996.
Effect of liquid culture requirements on antifungal antibiotic production by Streptomyces rimosus MY02 总被引:2,自引:0,他引:2
Streptomyces rimosus MY02 was isolated from a soil sample which was collected from the northeast of China. The effect of medium components (i.e. carbon and nitrogen sources) and other culture requirements (i.e. initial pH and temperature) on production of antifungal antibiotics by S. rimosus MY02 was investigated in our work. The best conditions for the strain MY02 in 250-ml Erlenmeyer flask, for example, initial pH, temperature, medium capacity, agitation rate, seed age, inoculum size and growth period, were 6.0, 28 degrees C, 50 ml, 180 rpm, 4 days, 10% (v/v) and 120 h, respectively. Components and dosage of the medium, which effect antibiotic production, were determined by uniform design combined with regression analysis; meanwhile, a regression model was established. The components and dosage of the best medium were starch, 53.313 g; defatted peanut powder, 9.376 g; (NH(4))(2)SO(4), 6.244 g; and NaCl, 5.836 g; in 1l of distilled water. Residual values obtained between the observed values by experiments and predicted values by the model are very low, and this result showed that the experimental results were well in consistence with the calculation results via the model. The antifungal antibiotic production by S. rimosus MY02 was improved by optimization of the components and culture requirements. The diameter of inhibition zone of the culture supernatant from S. rimosus MY02 against Fusarium oxysporium f sp. cucumarinum was 33.19 mm. 相似文献
997.
We found recently that beta-lactamase folds in the yeast cytosol to a native-like, catalytically active, and trypsin-resistant conformation, and is thereafter translocated into the ER and secreted to the medium. Previously, it was thought that pre-folded proteins cannot be translocated. Here we have studied in living yeast cells whether beta-lactamase, a tight globule in authentic form, must be unfolded for ER translocation. A beta-lactamase mutant (E166A) binds irreversibly benzylpenicillin via Ser(70) in the active site. We fused E166A to the C terminus of a yeast-derived polypeptide having a post-translational signal peptide. In the presence of benzylpenicillin, the E166A fusion protein was not translocated into the endoplasmic reticulum, whereas translocation of the unmutated variant was not affected. The benzylpenicillin-bound protein adhered to the endoplasmic reticulum membrane, where it prevented translocation of BiP, carboxypeptidase Y, and secretory proteins. Although the 321-amino acid-long N-terminal fusion partner adopts no regular secondary structure and should have no constraints for pore penetration, the benzylpenicillin-bound protein remained fully exposed to the cytosol, maintaining its signal peptide. Our data suggest that the beta-lactamase portion must unfold for translocation, that the unfolding machinery is cytosolic, and that unfolding of the remote C-terminal beta-lactamase is required for initiation of pore penetration. 相似文献
998.
Hedgehog signaling pathway is essential for pancreas specification in the zebrafish embryo. 总被引:4,自引:0,他引:4
Recent studies have implicated the signaling factor Sonic hedgehog (Shh) as a negative regulator of pancreatic development, but as a positive regulator of pancreas function in amniotes [1-4]. Here, using genetic analysis, we show that specification of the pancreas in the teleost embryo requires the activity of Hh proteins. Zebrafish embryos compromised in Hh signaling exhibit disruption in the expression of the pancreas-specifying homeobox gene pdx-1 and concomitantly show almost complete absence of the endocrine pancreas. Reciprocally, ubiquitous activation of the Hh pathway in wild-type embryos causes ectopic induction of endodermal pdx-1 expression and the differentiation of supernumerary endocrine cells. Our results suggest that Hh proteins influence pancreas specification via inductive interactions from the axial midline rather than through their localized expression in the endodermal cells themselves. 相似文献
999.
采用“定期起苗”法,从6 月10 日—8 月30 日止,分别统计从越冬块茎上萌发出的再生苗及其后代蔓生枝系再生苗的数量,从而得出扁秆藨草再生苗各旬株数增长的指数方程;又用“定株观察”法,对12 株越冬块茎上的再生苗及其全部后代植株开花、结实数量进行统计,探讨扁秆藨草有性繁殖的能力,然后进行综合计算,求得扁秆藨草种群的内禀增长率r=7.24,阐明了扁秆藨草很高的内禀增长率是其种群过度生长的根本原因;通过对其过度生长关键时刻的判断,选择灭草的关键期,有效地灭杀此种恶性杂草 相似文献
1000.
Guang‐Hua Wang Xue‐Qin Wang Fei Qiao Zeng‐Rong Zhu Jia‐An Cheng 《Molecular ecology resources》2013,13(5):811-819
A multiplex real‐time quantitative polymerase chain reaction (PCR) assay was developed to simultaneously detect the DNA of three rice planthoppers, that is, Sogatella furcifera (Horváth) (white‐backed planthopper), Nilaparvata lugens (Stål) (brown planthopper) and Laodelphax striatellus (Fallén) (small brown planthopper), in the gut of their predators. The sets of primers and ALLGlo probes were targeted to the regions of internal transcribed spacer 2 (ITS2) genes in nuclear ribosomal DNA (rDNA). The sensitivity, specificity and interference test for the multiplex real‐time quantitative PCR assay were analysed. The assay's detection limits were 100, 1000 and 100 copies for the white‐backed planthopper, the brown planthopper and the small brown planthopper, respectively. The specificity tests showed no cross‐reactivity with genomic DNA from 30 other dominant herbivores, saprophagous insects and predators from rice ecosystem for each planthopper species. The assay was used in a preliminary study of predation events on the three planthoppers by three major spiders viz., Pardosa pseudoannulata (Bösenberg et Strand), Ummeliata insecticeps (Bösenberg et Strand) and Tetragnatha maxillosa Thorell which each differ in their preferred microhabitat as well as their predatory habits in rice field, and the results showed their predation on each planthopper species could be well evaluated using this method. Therefore, the multiplex real‐time quantitative PCR assay provides a new tool to study the mechanisms of prey shifting and natural regulation of the three rice planthoppers by generalist predators in rice ecosystem. 相似文献