全文获取类型
收费全文 | 1301篇 |
免费 | 77篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 20篇 |
2021年 | 55篇 |
2020年 | 30篇 |
2019年 | 35篇 |
2018年 | 41篇 |
2017年 | 42篇 |
2016年 | 39篇 |
2015年 | 79篇 |
2014年 | 64篇 |
2013年 | 91篇 |
2012年 | 122篇 |
2011年 | 111篇 |
2010年 | 65篇 |
2009年 | 60篇 |
2008年 | 76篇 |
2007年 | 76篇 |
2006年 | 67篇 |
2005年 | 55篇 |
2004年 | 37篇 |
2003年 | 44篇 |
2002年 | 39篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 3篇 |
1968年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有1378条查询结果,搜索用时 15 毫秒
1.
2.
3.
T P Kliushnik S G Voloshchuk M V Aksenova G Sh Burbaeva 《Biulleten' eksperimental'no? biologii i meditsiny》1985,99(2):179-180
IEA of brain specific antigen 10-40-4 in human and animal organs and tissues was elaborated. The method permits measuring the concentration of the antigen within the range from 1 to 120 ng/ml. The use of the method made it possible to confirm brain specificity of protein 10-40-4, since its brain content is 1500 to 2000 times higher than in other organs, and to estimate the percentage of cross-reaction between antigenic determinants of brain specific antigen 10-40-4 from different species of animals. 相似文献
4.
Hydroboration of 5 alpha-cholest-8-ene, 5 alpha,14 beta-cholest-8-ene and 5 alpha,14 beta-cholest-7-ene provides a simple route to oxygenated steroids with 14 beta- and 8 alpha,14 beta- unnatural stereochemistry. 相似文献
5.
A C-glucoside of cholic acid was synthesized by the introduction of an acetyl group at position 3 alpha and direct one-pot C-glucosidation using 2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl chloride. 相似文献
6.
Lydiya I. Sergeeva Ivana Macháčková Tatyana N. Konstantinova Svetlana A. Golyanovskaya Josef Eder Oksana O. Zaltsman Jan Hanuš Nina P. Aksenova 《Journal of Plant Growth Regulation》1994,13(3):147-152
The levels of endogenous IAA and cytokinins (zeatin, zeatin riboside, isopentenyladenine, and isopentenyladenosine) were determined in potato plants cultured in vitro under red light (R) and blue light (B) on medium with or without hormones. On medium without hormones in B, plants contained much higher cytokinin levels, particularly in leaves and roots, and also slightly elevated IAA levels. Kinetin in the medium in B changed the distribution of cytokinins and significantly increased IAA level in roots. In R, the presence of kinetin led to an increased cytokinin level in the whole plant, while the IAA level was slightly lower. IAA in the medium in B decreased cytokinin level in all plant parts, while the IAA level did not change significantly. In R, the presence of IAA in the medium led to a moderate increase of CK level and to a significant increase in IAA level, especially in roots. Uptake of 1-14C-IAA and of 3H-zeatin was generally higher in B than in R. Higher percentage of IAA taken up in B was converted to conjugates in the roots. Metabolism of 3H-zeatin was similar in R and B with only slight differences in metabolite amounts.Thus, in all experimental situations in which tuber formation was stimulated, IAA level in roots and stolons rose significantly, stressing the importance of an IAA gradient for tuber formation. 相似文献
7.
Anastasia Klimova Ricardo Rodríguez-Estrella Guanliang Meng Jesús Neftalí Gutiérrez-Rivera María Luisa Jimenez-Jimenez Shanlin Liu 《Diversity & distributions》2023,29(3):438-461
Aim
Desert springs or oases are the only permanent mesic environments in highly water-limited arid regions. Oases have immense cultural, evolutionary and ecological importance for people and a high number of endemic and relic species. Nevertheless, they are also highly vulnerable ecosystems, with invasive species, overexploitation and climate change being the primary threats. We used the arthropod communities' spatiotemporal diversity and distribution patterns as a proxy to understand biodiversity dynamics in two geographically close but ecologically contrasting and highly threatened ecosystems: deserts and oases.Location
Baja California Peninsula, Mexico.Methods
Arthropod communities at five oases and surrounding desert scrub areas were sampled in two seasons. Using DNA metabarcoding and traditional taxonomic surveys, we tried to identify what biotic and abiotic characteristics of the habitat are important drivers of arthropod diversity and how these characteristics can change across spatial and temporal scales.Results
Over 6200 individuals representing 23 orders were collected. In oasis samples, the community composition fluctuated more in space (i.e. among sites) than in time (i.e. seasons). Thus, seasonal changes did not affect oasis community diversity and composition, but the dissimilarity among sites increased with geographic distance. Moreover, anthropic activities negatively correlated with arthropod diversity in oases. On the other hand, the season, geography (e.g. latitude) and biotic characteristics of the habitat (e.g. sampled scrub species) significantly affected the diversity and composition of the desert arthropod communities.Main Conclusions
Neutral dynamics (e.g. historical climatic events, dispersal limitation and spatial component) and human impact significantly influenced the biodiversity patterns of each oasis. In contrast, the habitat's seasonal variation and biotic characteristics were the most important variables influencing the diversity of the desert communities. Baja California oases harbour distinct invertebrate communities; therefore, each oasis should be conserved individually to preserve these unique assemblages. 相似文献8.
A N Tikhomirov I V Stupin O T Sushina T I Semenova T I Aksenova 《Arkhiv anatomii, gistologii i émbriologii》1975,69(11):47-52
The morphological analysis of the state of the heart during hypertermal perfusion with different conservants reveals clear dependence of the microcirculation and the activity of the heart upon the type of the conservant. Perfusion with a salt solution and hemodilution is accompanied by pronounced disorders in microcirculation and unsatisfactory parameters of the cardiac activity. Conservation with cryoprecipitated plasma is characterized by comparatively less microcirculatory disorders, but fails to give a reliable safety of the heart. When using medium 199, changes in microcirculation were found to be minimal and parameters of cardiac activity were satisfactory. In the complex of non-specific changes in microcirculatory vessels the maximum structural lability was revealed in blood capillaries and vessels of the postcapillary-venular link. 相似文献
9.
10.
M V Aksenova M V Karaseva G Sh Burbaeva 《Biulleten' eksperimental'no? biologii i meditsiny》1992,113(6):602-603
The absence of casein kinase 2 on blots of temporal cortex extracts from Alzheimer's disease patients (ADP) was shown using antiserum to casein kinase 2. Casein kinase 2 activity towards endogenous substrates and casein is 2-5 times less in ADP brain in comparison to normal controls. The fractions of heparin-binding proteins, containing protein substrates for phosphorylation, were isolated from temporal cortex of ADP and normal controls. The total amount of heparin-binding proteins from ADP brains is less than from control brains, and the polypeptide composition of these fractions is much more poop. 相似文献