全文获取类型
收费全文 | 7199篇 |
免费 | 248篇 |
国内免费 | 6篇 |
专业分类
7453篇 |
出版年
2024年 | 26篇 |
2023年 | 77篇 |
2022年 | 160篇 |
2021年 | 272篇 |
2020年 | 206篇 |
2019年 | 251篇 |
2018年 | 305篇 |
2017年 | 254篇 |
2016年 | 336篇 |
2015年 | 404篇 |
2014年 | 486篇 |
2013年 | 496篇 |
2012年 | 500篇 |
2011年 | 491篇 |
2010年 | 294篇 |
2009年 | 286篇 |
2008年 | 326篇 |
2007年 | 299篇 |
2006年 | 263篇 |
2005年 | 255篇 |
2004年 | 220篇 |
2003年 | 171篇 |
2002年 | 152篇 |
2001年 | 87篇 |
2000年 | 99篇 |
1999年 | 69篇 |
1998年 | 41篇 |
1997年 | 29篇 |
1996年 | 31篇 |
1995年 | 30篇 |
1994年 | 35篇 |
1993年 | 12篇 |
1992年 | 41篇 |
1991年 | 47篇 |
1990年 | 25篇 |
1989年 | 30篇 |
1988年 | 28篇 |
1987年 | 32篇 |
1986年 | 27篇 |
1985年 | 15篇 |
1984年 | 18篇 |
1983年 | 19篇 |
1982年 | 19篇 |
1981年 | 11篇 |
1979年 | 14篇 |
1978年 | 16篇 |
1975年 | 18篇 |
1973年 | 16篇 |
1972年 | 15篇 |
1970年 | 15篇 |
排序方式: 共有7453条查询结果,搜索用时 15 毫秒
41.
42.
Beadell JS Ishtiaq F Covas R Melo M Warren BH Atkinson CT Bensch S Graves GR Jhala YV Peirce MA Rahmani AR Fonseca DM Fleischer RC 《Proceedings. Biological sciences / The Royal Society》2006,273(1604):2935-2944
The introduction of avian malaria (Plasmodium relictum) to Hawaii has provided a model system for studying the influence of exotic disease on naive host populations. Little is known, however, about the origin or the genetic variation of Hawaii's malaria and traditional classification methods have confounded attempts to place the parasite within a global ecological and evolutionary context. Using fragments of the parasite mitochondrial gene cytochrome b and the nuclear gene dihydrofolate reductase-thymidylate synthase obtained from a global survey of greater than 13000 avian samples, we show that Hawaii's avian malaria, which can cause high mortality and is a major limiting factor for many species of native passerines, represents just one of the numerous lineages composing the morphological parasite species. The single parasite lineage detected in Hawaii exhibits a broad host distribution worldwide and is dominant on several other remote oceanic islands, including Bermuda and Moorea, French Polynesia. The rarity of this lineage in the continental New World and the restriction of closely related lineages to the Old World suggest limitations to the transmission of reproductively isolated parasite groups within the morphological species. 相似文献
43.
44.
45.
Nikele Nadur-Andrade Camila Squarzoni Dale Victoria Regina da Silva Oliveira Elaine Flamia Toniolo Regiane dos Santos Feliciano José Antonio da Silva Jr. Stella Regina Zamuner 《PLoS neglected tropical diseases》2016,10(10)
BackgroundEnvenoming induced by Bothrops snakebites is characterized by drastic local tissue damage that involves an intense inflammatory reaction and local hyperalgesia which are not neutralized by conventional antivenom treatment. Herein, the effectiveness of photobiomodulation to reduce inflammatory hyperalgesia induced by Bothrops moojeni venom (Bmv), as well as the mechanisms involved was investigated.Conclusion/SignificanceThese data demonstrate that LLLT interferes with mechanisms involved in nociception and hyperalgesia and modulates Bmv-induced nociceptive signal. The use of photobiomodulation in reducing local pain induced by Bothropic venoms should be considered as a novel therapeutic tool for the treatment of local symptoms induced after bothropic snakebites. 相似文献
46.
Colauto Nelson Barros da Eira Augusto Ferreira Linde Giani Andrea 《World journal of microbiology & biotechnology》2011,27(12):3015-3018
The preservation of Agaricus blazei is generally done by mycelial subculturing, but this technique may cause genetic degenerations. Despite this, there is not
an efficient protocol established to preserve this fungus and cryopreservation could be an alternative. This study aimed to
evaluate two freezing protocols for cryopreservation at −80°C of A. blazei strains. Five fungus strains grown on rice grains with husk and were transferred to glycerol (10%) in cryovials. Next, the
cryovials were submitted to two freezing temperature protocols: (1) cryopreservation starting at 25°C, then at 8°C for 30 min
and kept at −80°C; (2) cryopreservation starting at 25°C, then 8°C for 30 min, −196°C for 15 min and kept at −80°C. After
1 year of cryopreservation, the cryovials were thawed in a water bath at 30°C for 15 min and transferred to malt extract agar
medium. It was concluded that the one-year cryopreservation process of A. blazei, grown on rice grains and cryopreserved at −80°C in glycerol 10%, is viable. The slow freezing, from 8 to −80°C, is effective
whereas the fast freezing, from 8 to −196°C and then to −80°C, is ineffective. The different genetic characteristics among
the strains of this fungus do not interfere in the cryopreservation process. 相似文献
47.
48.
49.
Artur F. Castro-Rodrigues Yaxian Zhao Fátima Fonseca Guillaume Gabant Martine Cadene Gail A. Robertson João H. Morais-Cabral 《Journal of molecular biology》2018,430(24):5029-5049
The Drosophila EAG (dEAG) potassium channel is the founding member of the superfamily of KNCH channels, which are involved in cardiac repolarization, neuronal excitability and cellular proliferation. In flies, dEAG is involved in regulation of neuron firing and assembles with CaMKII to form a complex implicated in memory formation. We have characterized the interaction between the kinase domain of CaMKII and a 53-residue fragment of the dEAG channel that includes a canonical CaMKII recognition sequence. Crystal structures together with biochemical/biophysical analysis show a substrate–kinase complex with an unusually tight and extensive interface that appears to be strengthened by phosphorylation of the channel fragment. Electrophysiological recordings show that catalytically active CaMKII is required to observe active dEAG channels. A previously identified phosphorylation site in the recognition sequence is not the substrate for this crucial kinase activity, but rather contributes importantly to the tight interaction of the kinase with the channel. The available data suggest that the dEAG channel is a docking platform for the kinase and that phosphorylation of the channel's kinase recognition sequence modulates the strength of the interaction between the channel and the kinase. 相似文献
50.
L. S. Catenacci L. C. Martins K. M. De Vleeschouwer C. R. Cassano L. C. Oliveira G. Canale S. L. Deem J. S. Tello P. Parker P. F. C. Vasconcelos E. S. Travassos da Rosa 《EcoHealth》2018,15(4):777-791
From 2006 through 2014, we conducted seroepidemiological surveys on non-human primates and sloths to investigate the possible circulation of arboviruses in Bahia Atlantic Forest, Brazil. We collected a total of 196 samples from 103 Leontopithecus chrysomelas, 7 Sapajus xanthosternos, 22 Bradypus torquatus and 7 Bradypus variegatus. Serum samples were tested using neutralization test and hemagglutination inhibition test to detect total antibodies against 26 different arboviruses. The overall prevalence of arboviruses was 36.6% (51/139), with the genus Flavivirus having the highest prevalence (33.1%; 46/139), followed by Phlebovirus (5.0%; 7/139), Orthobunyavirus (4.3%; 6/139) and Alphavirus (0.7%; 1/139). Monotypic reactions suggest that the wild animals were exposed naturally to at least twelve arboviruses. Added results from the neutralization test, animals were exposed to thirteen arboviruses. Most of these viruses are maintained in transmission cycles independent of human hosts, although antibodies against dengue virus serotypes 1, 2 and 3 were found in this study. To our knowledge, this is the first study reporting exposure to arboviruses in L. chrysomelas, S. xanthosternos and B. torquatus. Our results also highlight that the Southern Bahia Atlantic Forest has a variety of vertebrate hosts and potential vectors, which may support the emergence or re-emergence of arboviruses, including those pathogenic to humans. 相似文献