全文获取类型
收费全文 | 7057篇 |
免费 | 503篇 |
出版年
2021年 | 54篇 |
2019年 | 61篇 |
2018年 | 71篇 |
2017年 | 57篇 |
2016年 | 89篇 |
2015年 | 146篇 |
2014年 | 162篇 |
2013年 | 352篇 |
2012年 | 310篇 |
2011年 | 322篇 |
2010年 | 177篇 |
2009年 | 173篇 |
2008年 | 325篇 |
2007年 | 294篇 |
2006年 | 332篇 |
2005年 | 318篇 |
2004年 | 302篇 |
2003年 | 304篇 |
2002年 | 306篇 |
2001年 | 296篇 |
2000年 | 290篇 |
1999年 | 236篇 |
1998年 | 93篇 |
1997年 | 84篇 |
1996年 | 70篇 |
1995年 | 70篇 |
1994年 | 63篇 |
1993年 | 76篇 |
1992年 | 163篇 |
1991年 | 172篇 |
1990年 | 157篇 |
1989年 | 149篇 |
1988年 | 146篇 |
1987年 | 126篇 |
1986年 | 102篇 |
1985年 | 83篇 |
1984年 | 103篇 |
1983年 | 83篇 |
1982年 | 49篇 |
1981年 | 47篇 |
1980年 | 58篇 |
1979年 | 96篇 |
1978年 | 69篇 |
1977年 | 75篇 |
1976年 | 41篇 |
1975年 | 41篇 |
1974年 | 43篇 |
1973年 | 45篇 |
1972年 | 43篇 |
1968年 | 34篇 |
排序方式: 共有7560条查询结果,搜索用时 15 毫秒
991.
992.
993.
Yoshida Y 《Parasitology international》2012,61(1):5-9
In the early stage of research on Clonorchis and clonorchiasis, Japanese parasitologists made a tremendous contribution on the elucidation of the life cycle of this parasite and on the epidemiology of the disease. Harujiro Kobayashi first identified cyprinoid fish as the second intermediate hosts for Clonorchis sinensis in 1912, Subsequently Parafossarulus snails were identified as the first intermediate host by Masatomo Muto in 1918. Kenso Ishisaka recorded the first human case of clonorchiasis in Japan in 1877, and two Japanese clinicians, Shigeru Matsumoto and Tsukasa Ohi, recorded the endemic nature of this disease in Korea and Taiwan respectively, in the same year, 1915. 相似文献
994.
Kohno T Ichikawa H Totoki Y Yasuda K Hiramoto M Nammo T Sakamoto H Tsuta K Furuta K Shimada Y Iwakawa R Ogiwara H Oike T Enari M Schetter AJ Okayama H Haugen A Skaug V Chiku S Yamanaka I Arai Y Watanabe S Sekine I Ogawa S Harris CC Tsuda H Yoshida T Yokota J Shibata T 《Nature medicine》2012,18(3):375-377
995.
Kusumi A Fujiwara TK Morone N Yoshida KJ Chadda R Xie M Kasai RS Suzuki KG 《Seminars in cell & developmental biology》2012,23(2):126-144
Virtually all biological membranes on earth share the basic structure of a two-dimensional liquid. Such universality and peculiarity are comparable to those of the double helical structure of DNA, strongly suggesting the possibility that the fundamental mechanisms for the various functions of the plasma membrane could essentially be understood by a set of simple organizing principles, developed during the course of evolution. As an initial effort toward the development of such understanding, in this review, we present the concept of the cooperative action of the hierarchical three-tiered meso-scale (2-300 nm) domains in the plasma membrane: (1) actin membrane-skeleton-induced compartments (40-300 nm), (2) raft domains (2-20 nm), and (3) dynamic protein complex domains (3-10nm). Special attention is paid to the concept of meso-scale domains, where both thermal fluctuations and weak cooperativity play critical roles, and the coupling of the raft domains to the membrane-skeleton-induced compartments as well as dynamic protein complexes. The three-tiered meso-domain architecture of the plasma membrane provides an excellent perspective for understanding the membrane mechanisms of signal transduction. 相似文献
996.
Ahmed M.H. Ali Jae Man Lee Mayumi Yoshida Kosuke Sakashita Jumpei Torii Takahiro Kusakabe Akinori Hirashima 《Journal of Asia》2012,15(4):567-572
The insect nervous system contains biogenic amines such octopamine (OA), which is synthesized from tyramine (TA) by catalysis of tyramine-β-hydroxylase (TβH). In this study, the Drosophila 70 kDa tyramine-β-hydroxylase (DmTβH) protein was purified after the recombinant nucleopolyhedrovirus isolated from Bombyx mori (BmNPV) containing the TβH gene was injected into the hemocoel of the fifth instar larvae from the d17 B. mori strain. Western blot analysis revealed an immunoreactive band with a molecular mass of 70 kDa. The products formed by incubating the enzyme reaction mixture were separated and detected by reverse phase high-performance liquid chromatography. The optimum pH, temperature, and incubation time for the conversion of TA to OA were 7.6, 25 °C, and 30 min, respectively. The inhibitory experiments using various concentrations of 1-(2-methoxy-5-methylphenyl) imidazole-2(3H)-thione (MMIT) showed that MMIT inhibited DmTβH dose-dependently and that this method can be applied for screening DmTβH inhibitors. 相似文献
997.
T Yoshida M Ishikawa T Niitsu M Nakazato H Watanabe T Shiraishi A Shiina T Hashimoto N Kanahara T Hasegawa M Enohara A Kimura M Iyo K Hashimoto 《PloS one》2012,7(8):e42676
Background
Meta-analyses have identified serum levels of brain-derived neurotrophic factor (BDNF) as a potential biomarker for major depressive disorder (MDD). However, at the time, commercially available human ELISA kits are unable to distinguish between proBDNF (precursor of BDNF) and mature BDNF because of limited BDNF antibody specificity. In this study, we examined whether serum levels of proBDNF, mature BDNF, and matrix metalloproteinase-9 (MMP-9), which converts proBDNF to mature BDNF, are altered in patients with MDD.Methodology/Principal Findings
Sixty-nine patients with MDD and 78 age- and gender-matched healthy subjects were enrolled. Patients were evaluated using 17 items on the Structured Interview Guide for the Hamilton Depression Rating Scale. Cognitive impairment was evaluated using the CogState battery. Serum levels of proBDNF, mature BDNF, and MMP-9 were measured using ELISA kits. Serum levels of mature BDNF in patients with MDD were significantly lower than those of normal controls. In contrast, there was no difference in the serum levels of proBDNF and MMP-9 between patients and normal controls. While neither proBDNF nor mature BDNF serum levels was associated with clinical variables, there were significant correlations between MMP-9 serum levels and the severity of depression, quality of life scores, and social function scores in patients.Conclusions/Significance
These findings suggest that mature BDNF may serve as a biomarker for MDD, and that MMP-9 may play a role in the pathophysiology of MDD. Further studies using larger sample sizes will be needed to investigate these results. 相似文献998.
Mika Saitoh Makoto Takeda Koichi Gotoh Fumihiko Takeuchi Tsuyoshi Sekizuka Makoto Kuroda Katsumi Mizuta Akihide Ryo Ryota Tanaka Haruyuki Ishii Hayato Takada Kunihisa Kozawa Ayako Yoshida Masahiro Noda Nobuhiko Okabe Hirokazu Kimura 《PloS one》2012,7(11)
We studied the molecular evolution of H gene in four prevalent Asian genotypes (D3, D5, D9, and H1) of measles virus (MeV). We estimated the evolutionary time scale of the gene by the Bayesian Markov Chain Monte Carlo (MCMC) method. In addition, we predicted the changes in structure of H protein due to selective pressures. The phylogenetic tree showed that the first division of these genotypes occurred around 1931, and further division of each type in the 1960–1970s resulted in four genotypes. The rate of molecular evolution was relatively slow (5.57×10−4 substitutions per site per year). Only two positively selected sites (F476L and Q575K) were identified in H protein, although these substitutions might not have imparted significant changes to the structure of the protein or the epitopes for phylactic antibodies. The results suggested that the prevalent Asian MeV genotypes were generated over approximately 30–40 years and H protein was well conserved. 相似文献
999.
Ito A Matsuo J Nakamura S Yoshida A Okude M Hayashi Y Sakai H Yoshida M Takahashi K Yamaguchi H 《PloS one》2012,7(1):e30270
Protochlamydia, an environmental chlamydia and obligate amoebal endosymbiotic bacterium, evolved to survive within protist hosts, such as Acanthamobae, 700 million years ago. However, these bacteria do not live in vertebrates, including humans. This raises the possibility that interactions between Protochlamydia and human cells could induce a novel cytopathic effect, leading to new insights into host-parasite relationships. Therefore, we studied the effect of Protochlamydia on the survival of human immortal cell line, HEp-2 cells and primary peripheral blood mononuclear cells (PBMC). Using mainly 4',6-diamidino-2-phenylindole staining, fluorescent in situ hybridization, transmission electron microscopy, and also TUNEL and Transwell assays, we demonstrated that the Protochlamydia induced apoptosis in HEp-2 cells. The attachment of viable bacterial cells, but not an increase of bacterial infectious progenies within the cells, was required for the apoptosis. Other chlamydiae [Parachlamydia acanthamoebae and Chlamydia trachomatis (serovars D and L2)] did not induce the same phenomena, indicating that the observed apoptosis may be specific to the Protochlamydia. Furthermore, the bacteria had no effect on the survival of primary PBMCs collected from five volunteers, regardless of activation. We concluded that Protochlamydia induces apoptosis in human-immortal HEp-2 cells and that this endosymbiont could potentially be used as a biological tool for the elucidation of novel host-parasite relationships. 相似文献
1000.
S Nishiumi T Kobayashi A Ikeda T Yoshie M Kibi Y Izumi T Okuno N Hayashi S Kawano T Takenawa T Azuma M Yoshida 《PloS one》2012,7(7):e40459