全文获取类型
收费全文 | 1176篇 |
免费 | 22篇 |
出版年
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 17篇 |
2017年 | 17篇 |
2016年 | 17篇 |
2015年 | 11篇 |
2014年 | 16篇 |
2013年 | 51篇 |
2012年 | 34篇 |
2011年 | 32篇 |
2010年 | 23篇 |
2009年 | 25篇 |
2008年 | 33篇 |
2007年 | 40篇 |
2006年 | 21篇 |
2005年 | 38篇 |
2004年 | 39篇 |
2003年 | 31篇 |
2002年 | 51篇 |
2001年 | 30篇 |
2000年 | 31篇 |
1999年 | 23篇 |
1997年 | 7篇 |
1992年 | 30篇 |
1991年 | 37篇 |
1990年 | 36篇 |
1989年 | 29篇 |
1988年 | 43篇 |
1987年 | 31篇 |
1986年 | 44篇 |
1985年 | 35篇 |
1984年 | 28篇 |
1983年 | 19篇 |
1982年 | 13篇 |
1981年 | 17篇 |
1980年 | 10篇 |
1979年 | 19篇 |
1978年 | 21篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1974年 | 13篇 |
1973年 | 16篇 |
1972年 | 13篇 |
1971年 | 19篇 |
1969年 | 8篇 |
1967年 | 10篇 |
1966年 | 7篇 |
1965年 | 6篇 |
排序方式: 共有1198条查询结果,搜索用时 15 毫秒
91.
Smirnov AV 《European journal of protistology》2007,43(2):87-94
An aquarium containing a portion of freshly collected brackish-water sediment from Nivå Bay (Øresund, Baltic Sea) was sampled to determine the species of amoebae present and refilled with inorganic salt medium to achieve freshwater salinity. After 2 months incubation, the diversity of amoebae was again studied, and the salinity was restored to the original level. The aquarium was incubated for a further 2 months and the amoeba fauna was studied for the last time. A number of freshwater species appeared in the sample after the first salinity shift, while some marine species disappeared. Most marine species did not re-appear after the salinity in the aquarium was restored, but one marine species not noted previously was recorded. The experiment illustrates the presence of ‘cryptic diversity’ of amoebae in natural habitats and demonstrates that laboratory manipulation of the salinity of a sample prior to inoculation may achieve an increased recovery of species from a brackish-water habitat. 相似文献
92.
Danny Morick Or Faigenbaum Margarita Smirnov Yakov Fellig Adi Inbal Moshe Kotler 《Applied and environmental microbiology》2015,81(10):3280-3287
Nervous necrosis virus (NNV) is a member of the Betanodavirus genus that causes fatal diseases in over 40 species of fish worldwide. Mortality among NNV-infected fish larvae is almost 100%. In order to elucidate the mechanisms responsible for the susceptibility of fish larvae to NNV, we exposed zebrafish larvae to NNV by bath immersion at 2, 4, 6, and 8 days postfertilization (dpf). Here, we demonstrate that developing zebrafish embryos are resistant to NNV at 2 dpf due to the protection afforded by the egg chorion and, to a lesser extent, by the perivitelline fluid. The zebrafish larvae succumbed to NNV infection during a narrow time window around the 4th dpf, while 6- and 8-day-old larvae were much less sensitive, with mortalities of 24% and 28%, respectively. 相似文献
93.
Chalisova NI Smirnov AV Morozova AIu 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2011,97(5):515-524
The effect of L-amino acids was investigated in organotypic tissue culture ofmesodermal tissue (spleen, myocardium) and ectodermal tissue (brain cortex) in mature rats. The low hydrophobic amino acids: asparagine, hystidine, serine, lysine, arginine and glutamine acid, induced the proliferation stimulation. The high hydrophobic amino acids had both the apoptose effect (spleen) and no effect at all (myocardium). The proliferation stimulation occurred in the ectodermal tissue under the effect of the high hydrophobic amino acids (asparagines acid, valine, threonine, methionine, leucine, isoleucine), whereas the low hydrophobic amino acids had no effect on the nervous tissue development. The combination of two amino acids one of which stimulated and another one inhibited the explant growth zone (or was not active in myocardium) lead to an increase of the stimulatory effect in meso- and ectodermal tissue. The amino acid modulated properties can be taken in consideration in synthesis of new regulatory peptides. 相似文献
94.
N. Yu. Sakharova A. A. Smirnov L. M. Mezhevikina L. A. Fialkovskaya D. V. Stasenko 《Russian Journal of Genetics》2011,47(6):726-731
The effect of enhanced green fluorescent protein (EGFP) on the in vitro viability of early embryos of C57BL/6-Tgn(ACTbEGFP)1Osb/J
mice has been studied. The number of viable ova in hemizygous females (−/egfp) has been shown to decrease. Irrespective of the EGFP level, it has no deleterious effect on the early development of embryos
obtained by reciprocal crossing of hemizygous (−/egfp) and wild-type (−/−) mice. 相似文献
95.
Khomyakova EA Zubin EM Smirnov IP Pozmogova GE Stetsenko DA Oretskaya TS 《Nucleosides, nucleotides & nucleic acids》2011,30(7-8):577-584
An efficient method for the synthesis of DNA or RNA oligonucleotide 2'-hydrazides is described. Fully deprotected oligonucleotides containing a hydrazide group at the 2'-position of a uridine residue were obtained by a novel two-step procedure: periodate cleavage of an oligonucleotide with 1,2-diol group followed by conversion of the aldehyde to hydrazide with an extended linker arm using a homobifunctional reagent succinic dihydrazide and NaBH(3)CN. The resulting oligonucleotide 2'-hydrazides were efficiently conjugated by a click-type reaction at acidic pH to aliphatic or aromatic aldehydes with or without NaBH(3)CN reduction to afford novel 2'-conjugates. 相似文献
96.
The Yucatan Peninsula is a karstic environment with almost no permanent surface water flows. All freshwater lentic systems
here are supported by underground water. We examined sediments, obtained with an Eckman dredge, from 25 different types of
water bodies (sinkholes or cenotes, lagoons, and wetlands), to investigate their biocenotic characteristics. All systems showed
differences in their zoocenoses, ostracods being the dominant group in most. Cladocera were scarce in the sediments, represented
by only eight genera. It can be partially related to the near absence of a littoral zone in cenotes, due to vertical walls,
and the lack of submersed vegetation. In spite of their importance, relatively little work has been done on ostracods from
this region of the world. 相似文献
97.
98.
To monitor gradual changes in the replication foci distribution during early S phase, different segments of newly synthesized DNA were visualized by immunocytochemical mapping of two consecutively incorporated deoxythymidine analogs in pulse-chase-pulse experiments in HeLa cells. The resulting dual-labeled fluorescence images were evaluated using cross-correlation function (CCF) analysis. General changes of CCF shape due to image deterioration caused by blur, noise, and lateral sampling (pixel size) were also discussed. Using CCF analysis of model images simulating either random initiation of new replication foci, or the firing of new foci in close proximity to completed ones, we were able to ascribe the changes in the early S replication foci distribution to the latter mechanism. In contrast to the data published previously, we monitored the dynamics of all replication foci for up to 3 h. In addition, we showed that the replication foci dynamics is well described by random walk model, so that the average de-localization of individual foci is proportional to square root of the applied chase. 相似文献
99.
The new higher level classification of eukaryotes with emphasis on the taxonomy of protists 总被引:23,自引:0,他引:23
Adl SM Simpson AG Farmer MA Andersen RA Anderson OR Barta JR Bowser SS Brugerolle G Fensome RA Fredericq S James TY Karpov S Kugrens P Krug J Lane CE Lewis LA Lodge J Lynn DH Mann DG McCourt RM Mendoza L Moestrup O Mozley-Standridge SE Nerad TA Shearer CA Smirnov AV Spiegel FW Taylor MF 《The Journal of eukaryotic microbiology》2005,52(5):399-451
This revision of the classification of unicellular eukaryotes updates that of Levine et al. (1980) for the protozoa and expands it to include other protists. Whereas the previous revision was primarily to incorporate the results of ultrastructural studies, this revision incorporates results from both ultrastructural research since 1980 and molecular phylogenetic studies. We propose a scheme that is based on nameless ranked systematics. The vocabulary of the taxonomy is updated, particularly to clarify the naming of groups that have been repositioned. We recognize six clusters of eukaryotes that may represent the basic groupings similar to traditional "kingdoms." The multicellular lineages emerged from within monophyletic protist lineages: animals and fungi from Opisthokonta, plants from Archaeplastida, and brown algae from Stramenopiles. 相似文献
100.