全文获取类型
收费全文 | 2750篇 |
免费 | 75篇 |
国内免费 | 94篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 19篇 |
2021年 | 32篇 |
2020年 | 24篇 |
2019年 | 33篇 |
2018年 | 32篇 |
2017年 | 37篇 |
2016年 | 56篇 |
2015年 | 79篇 |
2014年 | 117篇 |
2013年 | 114篇 |
2012年 | 96篇 |
2011年 | 95篇 |
2010年 | 101篇 |
2009年 | 190篇 |
2008年 | 163篇 |
2007年 | 147篇 |
2006年 | 158篇 |
2005年 | 111篇 |
2004年 | 87篇 |
2003年 | 80篇 |
2002年 | 54篇 |
2001年 | 42篇 |
2000年 | 51篇 |
1999年 | 57篇 |
1998年 | 43篇 |
1997年 | 43篇 |
1996年 | 42篇 |
1995年 | 58篇 |
1994年 | 55篇 |
1993年 | 42篇 |
1992年 | 46篇 |
1991年 | 52篇 |
1990年 | 48篇 |
1989年 | 48篇 |
1988年 | 49篇 |
1987年 | 39篇 |
1986年 | 49篇 |
1985年 | 48篇 |
1984年 | 45篇 |
1983年 | 25篇 |
1982年 | 49篇 |
1981年 | 47篇 |
1980年 | 44篇 |
1979年 | 37篇 |
1978年 | 8篇 |
1977年 | 11篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有2919条查询结果,搜索用时 15 毫秒
11.
G. S. C. BUSO Z. P. S. AMARAL R. P. V. BRONDANI M. E. FERREIRA 《Molecular ecology resources》2006,6(1):252-254
Efforts to develop molecular tools for genetic analysis and breeding of common bean in the tropics are still limited. The number of microsatellite markers available for the crop is small compared to other crops of similar social and economic importance. As part of a project to broaden the use of molecular tools in bean breeding, a genomic library enriched for AG/TC repeat sequences was constructed for Phaseolus vulgaris. Twenty microsatellite markers were initially developed and 10 were characterized using a panel of 85 representative accessions of the bean gene bank. The number of alleles per marker ranged from three to 10. The polymorphism information content (PIC) varied from 0.23 to 0.80. The results indicate that the new markers can be readily used in genetically analysis of common bean. 相似文献
12.
LI MINGFANG ZHENG XUEQING ZHU YONGQIANG WANG XIANGSHE LIANG SUYU LI LEI WU XINGRONG 《Molecular ecology resources》2006,6(4):1205-1207
Sixteen microsatellite loci were isolated from lychee (Litchi chinensis), all of which exhibited polymorphism (two or three alleles per locus), with levels of heterozygosity ranging from 0.021 to 0.900. These loci can help assess the genetic structure of lychee. 相似文献
13.
G. Harnischfeger 《BBA》1979,546(2):348-355
Cooling of chloroplasts to ?196°C can under certain circumstances lead to an erroneous analysis of energy distribution. After minimizing influences of sample geometry and effects of plastid concentration it is shown that externally induced membrane change leads to an increase in the ratio of the fluorescence emission spectrum. Similar alterations can be observed by variation of the rate of cooling the plastids to 77 K, especially if whole chloroplasts are used. The differences in emission ratios are indicative also of changes in initial energy distribution between the photosystems, given here by the value αN. This is inferred from experiments with either osmotically induced thylakoid disturbances or those effected through a slow cooling process. The circumstances and the significance of these observations are discussed. 相似文献
14.
E.M. del Campo A. del Hoyo C. Royo L.M. Casano R. lvarez E. Barreno 《Molecular phylogenetics and evolution》2010,57(3):1323-1328
15.
Heterotrissocladius marcidus (Walker, 1856) (Diptera: Chironomidae) inhabits aquatic habitats across the Holarctic and Oriental regions, including remote alpine glacial lakes. It is thus a promising species for studies of population structure and genetic diversity in these highly vulnerable habitats. Here, 21 polymorphic microsatellites for H. marcidus are described, obtained using 454 GS-FLX pyrosequencing. The number of alleles per locus varied from 2 to 9 and no significant linkage disequilibrium was observed. To test applicability, 40 individuals were used from two lakes in the Tatra Mts (Western Carpathians). Observed and expected heterozygosity varied from 0 to 0.9 and 0.102 to 0.888, respectively. In both populations, three loci deviated significantly from Hardy–Weinberg equilibrium after Bonferroni correction, probably due to presence of null alleles or undetected biological processes. Application of microsatellites was tested on six alpine lake populations. Bayesian cluster analysis assigned individuals to lakes of their origin and revealed limited gene-flow between them. Five loci were successfully cross-amplified in the related midge Macropelopia sp. (Tanypodinae) and two in Pseudodiamesa branickii (Nowicki, 1873) (Diamesinae). The microsatellites described herein proved to be useful for genetic studies of alpine populations, and can provide important data for management and conservation of these threatened habitats. 相似文献
16.
《Saudi Journal of Biological Sciences》2022,29(1):650-659
Sporadic rains in the Atacama Desert reveal a high biodiversity of plant species that only occur there. One of these rare species is the “Red añañuca” (Zephyranthes phycelloides), formerly known as Rhodophiala phycelloides. Many species of Zephyranthes in the Atacama Desert are dangerously threatened, due to massive extraction of bulbs and cutting of flowers. Therefore, studies of the biodiversity of these endemic species, which are essential for their conservation, should be conducted sooner rather than later. There are some chloroplast genomes available for Amaryllidaceae species, however there is no complete chloroplast genome available for any of the species of Zephyranthes subgenus Myostemma. The aim of the present work was to characterize and analyze the chloroplast of Z. phycelloides by NGS sequencing. The chloroplast genome of the Z. phycelloides consists of 158,107 bp, with typical quadripartite structures: a large single copy (LSC, 86,129 bp), a small single copy (SSC, 18,352 bp), and two inverted repeats (IR, 26,813 bp). One hundred thirty-seven genes were identified: 87 coding genes, 8 rRNA, 38 tRNA and 4 pseudogenes. The number of SSRs was 64 in Z. phycelloides and a total of 43 repeats were detected. The phylogenetic analysis of Z. phycelloides shows a distinct subclade with respect to Z. mesochloa. The average nucleotide variability (Pi) between Z. phycelloides and Z. mesochloa was of 0.02000, and seven loci with high variability were identified: psbA, trnSGCU-trnGUCC, trnDGUC-trnYGUA, trnLUAA-trnFGAA, rbcL, psbE-petL and ndhG-ndhI. The differences between the species are furthermore confirmed by the high amount of SNPs between these two species. Here, we report for the first time the complete cp genome of one species of the Zephyranthes subgenus Myostemma, which can be used for phylogenetic and population genomic studies. 相似文献
17.
By using six polymorphic microsatellite loci, the population genetic diversity and structure of 120 individuals of Portunus trituberculatus were examined in five wild populations representing different geographical and ecological ranges along the coast of China. Middle level of genetic diversity of P. trituberculatus was revealed by observed heterozygosity, allele number and Shannon information index. Pairwise population differentiations were found between all pairs of populations except Beihai (BH) and Qingdao (QD) (P < 0.05). The greatest differentiation was detected between Yingkou (YK) and QD populations. It was inconsistent with the result in previous study using mitochondrial control region, which showed no differentiation between QD and YK population. Recent bottleneck was identified in Ningbo (NB) population under TPM and IAM models, as well as Dandong (DD) and QD populations under IAM model. Additionally, compared with YK, QD, DD and BH populations, lower historical effective population size with lower genetic diversity were detected in NB population, which called for urgent assessment of the ecological and economic potential of NB fisheries. 相似文献
18.
Preillumination of intact cells of the eukaryotic, halotolerant, cell-wall-less green alga Dunaliella salina induces a dark ATPase activity the magnitude of which is about 3–5-fold higher than the ATPase activity observed in dark-adapted cells. The light-induced activity arises from the activation and stabilization in vivo of chloroplast coupling factor 1 (CF1). This activity, 150–300 μmol ATP hydrolyzed/mg Chl per h, rapidly decays (with a half-time of about 6 min at room temperature) in intact cells but only slowly decays (with a half-time of about 45 min at room temperature) if the cells are lysed by osmotic shock immediately after illumination. The activated form of the ATPase in lysed cells is inhibited if the membranes are treated with ferri- but not ferrocyanide, suggesting that the stabilization of the activated form of CF1 is due to the reduction of the enzyme in vivo in the light. 相似文献
19.
Maryse A. Block Jacques Joyard Roland Douce 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,631(1):210-219
Chloroplasts isolated from fully developed spinach leaves and incubated in the presence of isopentenyl pyrophosphate were able to synthesize rapidly geranylgeranyl chlorophyll a and geranylgeraniol.The biosynthesis of the geranylgeraniol derivatives from isopentenyl pyrophosphate is a compartimentalized process. The membrane fractions (thylakoid and envelope membranes) were essentially unable to synthesize geranylgeraniol, geranylgeranyl pyrophosphate and geranylgeranyl chlorophyll a. When stromal and thylakoid fractions were combined the capacity to synthesize geranylgeranyl chlorophyll a and geranylgeraniol was restored. When stromal and envelope membrane fractions were combined the capacity to synthesize geranylgeranyl pyrophosphate and geranylgeraniol was restored. The products of the reaction were discharged inside the lipid phase of the membranes. 相似文献
20.