全文获取类型
收费全文 | 1048篇 |
免费 | 97篇 |
国内免费 | 2篇 |
出版年
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 22篇 |
2017年 | 21篇 |
2016年 | 32篇 |
2015年 | 46篇 |
2014年 | 45篇 |
2013年 | 54篇 |
2012年 | 84篇 |
2011年 | 84篇 |
2010年 | 45篇 |
2009年 | 56篇 |
2008年 | 61篇 |
2007年 | 82篇 |
2006年 | 82篇 |
2005年 | 72篇 |
2004年 | 68篇 |
2003年 | 43篇 |
2002年 | 71篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 5篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1930年 | 1篇 |
1929年 | 2篇 |
1928年 | 1篇 |
1924年 | 1篇 |
排序方式: 共有1147条查询结果,搜索用时 31 毫秒
1.
Mykola Isaiev Sergii Burian Leonid Bulavin Michel Gradeck Fabrice Lemoine Konstantinos Termentzidis 《Molecular simulation》2016,42(11):910-915
Spherical and cylindrical water droplets on silicon surface are studied to tune the silicon–oxygen interaction. We use molecular dynamics simulations to estimate the contact angle of two different shaped droplets. We found that the cylindrical droplets are independent of the line tension as their three phases curvature is equal zero. Additionally, we compare an analytical model, taking into account or not the Tolman length and we show that for spherical small size droplets, this length is important to be included, in contrast to cylindrical droplets in which the influence of the Tolman length is negligible. We demonstrate that the usual convenient way to exclude linear tension in the general case can give wrong results. Here, we consider cylindrical droplets, since their contact angle does not depend on the droplet size in the range of few to 10ths of nanometres. The droplets are stabilised due to the periodic boundary conditions. This allows us to propose a new parameterisation for nanoscale droplets, which is independent the size of the droplets or its shape, minimising at the same time the calculation procedure. With the proposed methodology, we can extract the epsilon parameter of the interaction potential between a liquid and a solid from the nanoscaled molecular simulation with only as input the macrosized experimental wetting angle for a given temperature. 相似文献
2.
Gabrielle C. Winters Gianluca Polese Anna Di Cosmo Leonid L. Moroz 《Journal of morphology》2020,281(7):790-801
Neuropeptide Y (NPY) is an evolutionarily conserved neurosecretory molecule implicated in a diverse complement of functions across taxa and in regulating feeding behavior and reproductive maturation in Octopus. However, little is known about the precise molecular circuitry of NPY-mediated behaviors and physiological processes, which likely involve a complex interaction of multiple signal molecules in specific brain regions. Here, we examined the expression of NPY throughout the Octopus central nervous system. The sequence analysis of Octopus NPY precursor confirmed the presence of both, signal peptide and putative active peptides, which are highly conserved across bilaterians. In situ hybridization revealed distinct expression of NPY in specialized compartments, including potential “integration centers,” where visual, tactile, and other behavioral circuitries converge. These centers integrating separate circuits may maintain and modulate learning and memory or other behaviors not yet attributed to NPY-dependent modulation in Octopus. Extrasomatic localization of NPY mRNA in the neurites of specific neuron populations in the brain suggests a potential demand for immediate translation at synapses and a crucial temporal role for NPY in these cell populations. We also documented the presence of NPY mRNA in a small cell population in the olfactory lobe, which is a component of the Octopus feeding and reproductive control centers. However, the molecular mapping of NPY expression only partially overlapped with that produced by immunohistochemistry in previous studies. Our study provides a precise molecular map of NPY mRNA expression that can be used to design and test future hypotheses about molecular signaling in various Octopus behaviors. 相似文献
3.
4.
5.
In the albino mutant of an Okinawa strain of Locusta migratoria (L.) (Orthoptera: Acrididae), albinism is caused by the absence of the dark‐colour‐inducing neurohormone (DCIN), which is present in the corpora cardiaca (CC) of normally coloured phenotypes. This study tests whether the absence of DCIN is responsible for albinism in an albino mutant of another locust, Schistocerca gregaria (Forsk.) (Orthoptera: Acrididae). This seemed feasible because a single Mendelian unit controls albinism in both species. However, implantation of CC, or injection of an extract of CC, from albino donors of S. gregaria, induce dark coloration in crowded nymph recipients of the Okinawa albino mutant of L. migratoria, as effectively as do implanted CC, or injections of extract of CC, from normal phenotype donors of S. gregaria. Therefore, DCIN is present in the albino mutant of S. gregaria, and consequently, the albinism in this mutant is not caused by its absence. Implantation of CC, or injection of extracts of CC, from albino donors of S. gregaria to conspecific albino nymphs does not induce darkening. Only extremely high doses of synthetic DCIN injected into albino nymphs of S. gregaria are effective, inducing some darkening. The dose to induce such darkening in albino nymphs of S. gregaria is 50 nmol, ≈ 5 × 106 times higher than that (10 femtomol) needed to induce equivalent darkening in nymphs of the Okinawa albinos of L. migratoria. The results are discussed and some possible explanations of the observed effects outlined. 相似文献
6.
Leonid Doljanski 《Development genes and evolution》1932,126(1):207-212
Ohne Zusammenfassung 相似文献
7.
V N Gorbacheva N I Lebedev M V Miakinnikova T M Ovcharenko 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》1982,(9):42-45
Clinical, bacteriological, serological and epidemiological studies of ozena morbidity among the population of Minsk were carried out in 1970-1980. On January 1, 1981, the ozena morbidity rate among the inhabitants of Minsk was 26.72%. Ozena was found to affect mainly children and women. A wide spread of the family foci of this disease (31.68%) was revealed. The results of this study indicate that the source of K. ozaenae is a sick person who begins to excrete the bacteria in the prodromal period of the disease and may continue to excrete them for many years. The transfer of K. ozaenae occurs probably by droplet or contact infection. The droplet infection is less active in the absence of symptoms (coughing, sneezing) facilitating excretion of the infective agent into the air and in cases of the low susceptibility of persons to ozena. The main measures for controlling ozena are the timely detection and sanitation of the sources of ozena, as well as the current disinfection of the infection foci in apartments. 相似文献
8.
We model the vague-to-crisp dynamics of forming percepts in the brain by combining two methodologies: dynamic logic (DL) and operant learning process. Forming percepts upon the presentation of visual inputs is likened to model selection based on sampled evidence. Our framework utilizes the DL in selecting the correct “percept” among competing ones, but uses an intrinsic reward mechanism to allow stochastic online update in lieu of performing the optimization step of the DL framework. We discuss the connection of our framework with cognitive processing and the intentional neurodynamic cycle. 相似文献
9.
A V Kabanov S V Vinogradov A V Ovcharenko A V Krivonos N S Melik-Nubarov V I Kiselev E S Severin 《FEBS letters》1990,259(2):327-330
To enhance the penetration of oligonucleotide ('oligo') into cells, the oligo was combined with the hydrophobic undecyl residue. Using the 'DNA-synthesator', we synthesized oligo, complementary to the loop-forming site of the RNA, encoding polymerase 3 of the influenza virus (type A), and combined it with the undecyl residue added to the 5' terminal phosphate group. It was found that the modified oligo effectively suppresses the influenza A/PR8/34 (H1N1) virus reproduction and inhibits the synthesis of virus-specific proteins in MDCK cells. Under the same conditions, the non-modified antisense oligo and modified nonsense oligo did not affect the virus development. 相似文献
10.
Leonid Beigelman Alexander Karpeisky Jasenka Matulic-Adamic Carolyn Gonzalez Nassim Usman 《Nucleosides, nucleotides & nucleic acids》2013,32(3-5):907-910
Abstract The synthesis of 1-deoxy-D-ribofuranose-3-(2-cyanoethyl N,N-diisopropylphosphoramidite) (6) from D-ribose and its incorporation into a hammerhead ribozyme is described. 相似文献