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81.
Ying Liu Jie Tang Jingjing Li Maurycy Daroch Jay J. Cheng 《Applied microbiology and biotechnology》2014,98(23):9643-9652
Thraustochytrids have recently emerged as a promising source for docosahexaenoic acid (DHA) production due to their high growth rate and oil content. In this study, two thraustochytrid isolates, Aurantiochytrium sp. PKU#SW7 and Thraustochytriidae sp. PKU#Mn16 were used for DHA production. Following growth parameters were optimized to maximize DHA production: temperature, pH, salinity, and glucose concentration. Both isolates achieved the highest DHA yield at the cultivation temperature of 28 °C, pH 6, 100 % seawater, and 2 % glucose. A DHA yield of 1.395 g/l and 1.426 g/l was achieved under the optimized culture conditions. Further investigation revealed that both isolates possess simple fatty acids profiles with palmitic acid and DHA as their dominant constituents, accounting for ~79 % of total fatty acids. To date, very few studies have focused on the DHA distribution in various lipid fractions which is an important factor for identifying strains with a potential for industrial DHA production. In the present study, the lipids profiles of each strain both revealed that the majority of DHA was distributed in neutral lipids (NLs), and the DHA distribution in NLs of PKU#SW7 was exclusively in the form of triacylglycerols (TAGs) which suggest that PKU#SW7 could be utilized as an alternative source of DHA for dietary supplements. The fermentation process established for both strains also indicating that Aurantiochytrium sp. PKU#SW7 was more suitable for cultivation in fermenter. In addition, the high percentage of saturated fatty acids produced by the two thraustochytrids indicates their potential application in biodiesel production. Overall, our findings suggest that two thraustochytrid isolates are suitable candidates for biotechnological applications. 相似文献
82.
树叶凋落物在受酸性矿山废水污染溪流中的分解 总被引:2,自引:0,他引:2
为了解华南地区酸性矿山废水对溪流中树叶分解的影响,在广东省大宝山矿区附近的1条受酸性矿山废水污染(pH值为2.7—3.4且富含多种重金属元素)的3级溪流中,利用2种孔径(5ram的网袋和0.1ram的布袋)的分解网袋对2种树叶(人面子和蒲桃)进行了为期101d的树叶分解研究。结果表明,人面子树叶网袋和布袋中的树叶干重剩余率分别为39%和48%,而蒲桃树叶网袋和布袋中的干重剩余率仍保持较高的水平,分别为61%和70%。根据指数衰减模型计算出树叶分解的半衰期,人面子树叶在网袋和布袋中的分解半衰期分别为57d和69d,而蒲桃树叶则分别为14-4d和217d。蒲桃树叶的分解速率明显比人面子树叶慢。在网袋中定殖的底栖动物主要是集食者,其中优势类群为摇蚊幼虫,占底栖动物个体总数的99%。摇蚊种群在网袋中的数量波动对2种树叶分解速率的影响并不明显。结果表明,受酸性矿山废水的影响,底栖动物群落的多样性大为减少。同时由于各种金属氧化物在树叶表面的不断沉淀,使树叶处于缺氧状态,抑制了微生物的活动,导致树叶分解速率大为降低。 相似文献
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84.
Martin Husemann Suk Namkung Jan C. Habel Patrick D. Danley Axel Hochkirch 《Zoologica scripta》2012,41(5):515-526
Husemann, M., Namkung, S., Habel, J.C., Danley, P.D. & Hochkirch, A. (2012). Phylogenetic analyses of band‐winged grasshoppers (Orthoptera, Acrididae, Oedipodinae) reveal convergence of wing morphology. —Zoologica Scripta, 41, 515–526. Historically, morphological traits have been used to examine the relationships of distantly related taxa with global distributions. The use of such traits, however, may be misleading and may not provide the resolution needed to distinguish various hypotheses that may explain the distribution patterns of widely distributed taxa. One such taxon, the Oedipodine grasshoppers, contains two tribes principally defined by wing morphologies: the Bryodemini have broad wings whereas Sphingonotini are narrow‐winged. Through the use of morphological features alone, hypotheses concerning the evolution of these tribes cannot be distinguished. To differentiate hypotheses that may explain the distribution of Oedipodines, such as vicariance, natural dispersal and anthropogenic translocation, we used two mitochondrial and three nuclear gene fragments to reconstruct the phylogenetic relationships within and between the two tribes, and employed a molecular clock to evaluate the hypotheses of vicariance and dispersal. Our results clearly reject monophyly of the tribes and revealed monophyletic Old and New World clades, which is in agreement with previous molecular studies. The split between both clades was dated at 35 Ma (±12 Ma). This clearly rejects the vicariance hypothesis and supports a single invasion via the Beringian land bridge. In addition, our data clearly show that the similarities in wing morphology used for distinguishing both tribes are the result of at least one convergent event. Our study shows that interpretations of relationships based on the currently accepted taxonomy in the study groups will be error prone. We suggest that future revisions that consider our findings are required. 相似文献
85.
Ying?Wu Rui?Wu Bangjiao?Zhang Tingting?Jiang Ning?Li Kai?Qian Bao?LiuEmail author Jian?ZhangEmail author 《Plant Growth Regulation》2012,66(2):137-143
Gardenia jasminoides Ellis is an evergreen tropical plant and favorite to gardeners throughout the world. Several studies have documented that
in vitro micropropagation can be used for clonal propagation of G. jasminoides Ellis, the efficiency remained low. In addition, no information is available on the genetic and epigenetic fidelity of the
micropropagated plants. Here, we report on a simplified protocol for high efficient micropropagation of G. jasminoides Ellis cv. “Kinberly” based on enhanced branching of shoot-tips as explants. The protocol consisted of sequential use of three
media, namely, bud-induction, elongation and root-induction. By using two molecular markers, amplified fragment length polymorphism
(AFLP) and methylation sensitive amplified polymorphism (MSAP), we analyzed the genetic and DNA methylation pattern stability
of 23 morphologically normal plants randomly taken from a sub-population (>100) of micropropagated plants originated from
a single shoot-tip. We found that of >1,000 scored AFLP bands across the 23 micropropagated plants, no incident of genetic
variation was detected. In contrast, of 750 scored MSAP bands, moderate but clear alteration in several DNA methylation patterns
occurred in the majority of the 23 micropropagated plants. The changed methylation patterns involved both CG and CHG sites
representing either hyper- or hypo-methylation, which occurred without altering the total methylation levels partly due to
concomitant hyper- and hypo-methylation alterations. Our results indicated that epigenetic instability in the form of DNA
methylation patterns can be susceptible to the in vitro micropropagation process for G. jasminoides Ellis, and needs to be taken into account in the process of large-scale commercial propagation of this plant. 相似文献
86.
Lambros MP Parsa C Mulamalla H Orlando R Lau B Huang Y Pon D Chow M 《Biochemical and biophysical research communications》2011,411(1):102-106
Mature adipocytes are excellent candidates to influence tumor behavior through heterotypic signaling processes since these cells produce hormones, growth factors, cytokines and other molecules, a heterogeneous group of molecules named adipokines. Using a 2D coculture system, we demonstrate that breast tumor cells previously co-cultivated with mature adipocytes exhibit radioresistance and an earlier and higher increase in the effector kinase Chk1, a phenotype that was associated with decreased cell death as compared to tumor cells grown alone. Interestingly, the adipocytes-induced tumor changes taking place during the coculture time preceding the exposure to IR were sufficient to confer the radioresistant effect. Notorious among the changes brought by adipocytes was the significant increase of IL-6 expression in tumor cells, whose activity may well account for the observed tumor cell protection from IR toxicity. Indeed, our data confirmed the protective role of this cytokine as tumor cells incubated after irradiation with recombinant IL-6 exhibit an increased in Chk1 phosphorylation and a radioresistant phenotype, thus far recapitulating the effects observed in the presence of adipocytes. Our current study sheds light on a new role of tumor-surrounding adipocytes in fostering a radioresistant phenotype in breast tumors, a finding that might have important clinical implications in obese patients that frequently exhibit aggressive diseases. 相似文献
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