全文获取类型
收费全文 | 1515篇 |
免费 | 107篇 |
国内免费 | 1篇 |
专业分类
1623篇 |
出版年
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 18篇 |
2015年 | 21篇 |
2014年 | 35篇 |
2013年 | 184篇 |
2012年 | 52篇 |
2011年 | 59篇 |
2010年 | 44篇 |
2009年 | 49篇 |
2008年 | 84篇 |
2007年 | 96篇 |
2006年 | 91篇 |
2005年 | 99篇 |
2004年 | 94篇 |
2003年 | 88篇 |
2002年 | 78篇 |
2001年 | 26篇 |
2000年 | 21篇 |
1999年 | 27篇 |
1998年 | 26篇 |
1997年 | 20篇 |
1996年 | 27篇 |
1995年 | 27篇 |
1994年 | 12篇 |
1993年 | 21篇 |
1992年 | 21篇 |
1991年 | 16篇 |
1990年 | 26篇 |
1989年 | 25篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 17篇 |
1983年 | 15篇 |
1982年 | 26篇 |
1981年 | 17篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 13篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1969年 | 2篇 |
排序方式: 共有1623条查询结果,搜索用时 0 毫秒
71.
Treatment of Mid‐Pregnant Mice with KRN633, an Inhibitor of Vascular Endothelial Growth Factor Receptor Tyrosine Kinase,Induces Abnormal Retinal Vascular Patterning in Their Newborn Pups 下载免费PDF全文
Akane Morita Tsutomu Nakahara Naomichi Abe Asami Mori Kenji Sakamoto Tohru Nagamitsu Kunio Ishii 《Birth defects research. Part B, Developmental and reproductive toxicology》2014,101(4):293-299
We previously reported that treatment of mid‐pregnant mice with KRN633, a vascular endothelial growth factor receptor tyrosine kinase inhibitor, caused fetal growth restriction resulting from diminished vascularization in the placenta and fetal organs. In this study, we examined how the treatment of mid‐pregnant mice with KRN633 affects the development and morphology of vascular components (endothelial cells, pericytes, and basement membrane) in the retinas of their newborn pups. Pregnant mice were treated with KRN633 (5 mg/kg) once daily from embryonic day 13.5 until the day of delivery. Vascular components were examined using immunohistochemistry with specific markers for each component. Radial vascular growth in the retina was slightly delayed until postnatal day 4 (P4) in the newborn pups of KRN633‐treated mothers. On P8, compared with the pups of control mothers, the pups of KRN633‐treated mothers exhibited decreased numbers of central arteries and veins and abnormal branching of the central arteries. No apparent differences in pericytes or basement membrane were observed between the pups of control and KRN633‐treated mothers. These results suggest that a critical period for determining retinal vascular patterning is present at the earliest stages of retinal vascular development, and that the impaired vascular endothelial growth factor signaling during this period induces abnormal architecture in the retinal vascular network 相似文献
72.
Two anthiine fishes from the eastern tropical Atlantic are described as newHolanthias cyprinoides andAnthias helenensis. The former is distinguished from the other Atlantic species ofHolanthias in having the forked caudal fin with rounded lobes and from the Indo-Pacific species in having no elongated dorsal spines or soft rays. The latter is closely related toAnthias asperilinguis Günther (South America, Atlantic coast), but differs from it in having more pectoral fin rays and more gill rakers. The present investigation onAnthias suggests that AtlanticAnthias is a genus distinct fromPseudanthias of the Indo-Pacific. 相似文献
73.
74.
This is the first detailed report of social factors affecting fish-eating in Japanese macaques under natural circumstances. We video-recorded a complete event of fish eating, involving a new fish food species for the monkeys on Koshima island. Following the discovery of a large beached sea bass by a peripheral male, we observed a total of 16 individuals feeding on the fish in turns, and interacting around it. The rank order of access to the fish was mainly explained by the spatial position of group members, whereas dominance determined how long the fish was monopolized. Although limited, the tolerated presence of close-bystanders while feeding was affected by kinship and affiliation. Genealogic data suggested that fish-eating behavior was well maintained in terms of maternal lineages. This report should contribute to a better understanding of how social features may constrain the long-term diffusion of feeding innovations in free-ranging primate groups. 相似文献
75.
Matsuki A Yamamoto S Nakagami H Aoki M Tamai K Matsumoto K Nakamura T Ogihara T Kaneda Y Morishita R 《Biochemical and biophysical research communications》2004,315(1):59-65
Recently, a novel therapeutic treatment for ischemic diseases using angiogenic growth factors to augment collateral artery development has been proposed. As intramuscular injection of naked human hepatocyte growth factor (HGF) plasmid DNA induced therapeutic angiogenesis in several animal test subjects, we have started a clinical trial to treat peripheral arterial disease. However, one might assume that over-expression of angiogenic growth factors could enhance tumor growth. To resolve this issue, we examined the over-expression of HGF in tumor bearing mice. Tumors on their backs were prepared with an intradermal inoculation of A431, human epidermoid cancer cells expressing c-Met. These mice were intramuscularly injected with human HGF plasmid or control plasmid into the femoral muscle. Human HGF concentration was increased only in the femoral muscle, but not in blood. Although recombinant HGF stimulated the growth of A431 cells in vitro, temporally and locally HGF elevation in hindlimb had no effect on tumor growth in mice. 相似文献
76.
Yumi Nakayama Weiping Su Kei-Ichi Katayama Hiroyuki Nakayama Kunio Doi 《Experimental Animals》2004,53(2):165-169
Pregnant mice of the BALB/c CrSlc strain were experimentally infected with the D variant of encephalomyocarditis virus (EMC-D, 5 x 10(2) PFU/head) on three different gestational days (GD). Mice were intraperitoneally inoculated with EMC-D on 11, 13 and 15 GD and sacrificed 3 days post inoculation. There was no significant difference in the fetal mortality among all inoculation groups. Placenta showed higher virus titer than fetus and dam's serum in all inoculation groups, and the virus titer of the fetus was lowest in the 15GD group. Histopathological changes and signals of viral RNAs detected by in situ hybridization were observed almost restricted to the spongiotrophoblast layer of the placenta in all inoculation groups, and the signals were strongest in the 11GD group. In the fetus of the11GD group, signals of viral RNAs were also seen in myocardium and hepatocytes. Ultrastructurally, intracytoplasmic aggregations of virus-like particles in crystalline array were observed in trophoblast cells and giant cells in the spongiotrophoblast layer in all inoculation groups. 相似文献
77.
Tachibana T Hirofuji K Matsumoto M Furuse M Hasegawa S Yoshizawa F Sugahara K 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2004,137(1):183-188
The present study was carried out to investigate whether the hypothalamus is involved in the anorexic effect of glucagon-like peptide-1 (GLP-1) in chicks. To examine this, Fos expression in the chick hypothalamus were immunohistochemically detected after intracerebroventricular (ICV) injection of 30-pmol GLP-1. ICV injection of GLP-1 stimulated the expression of Fos-like immunoreactive (FLI) cells in the ventromedial hypothalamic nucleus (VMN). When 15-pmol GLP-1 was directly injected into the chick VMN, the chick's food intake was significantly decreased compared with the control treatment. Microinjection of GLP-1 into the (LHA) also inhibited feeding in chicks, although ICV injection of GLP-1 did not stimulate FLI expression in the brain area. These results suggest that VMN and some brain regions are involved in the anorexic effect of GLP-1 in chicks. 相似文献
78.
A novel HLA-A*3303-restricted minor histocompatibility antigen encoded by an unconventional open reading frame of human TMSB4Y gene 总被引:4,自引:0,他引:4
Torikai H Akatsuka Y Miyazaki M Warren EH Oba T Tsujimura K Motoyoshi K Morishima Y Kodera Y Kuzushima K Takahashi T 《Journal of immunology (Baltimore, Md. : 1950)》2004,173(11):7046-7054
Female-to-male hemopoietic stem cell transplantation (HSCT) elicits T cell responses against male-specific minor histocompatibility (H-Y) Ags encoded by the Y chromosome. All previously identified H-Y Ags are encoded by conventional open reading frames, but we report in this study the identification of a novel H-Y Ag encoded in the 5'-untranslated region of the TMSB4Y gene. An HLA-A*3303-restricted CD8(+) CTL clone was isolated from a male patient after an HSCT from his HLA-identical sister. Using a panel of cell lines carrying Y chromosome terminal deletions, a narrow region controlling the susceptibility of these target cells to CTL recognition was localized. Minigene transfection and epitope reconstitution assays identified an 11-mer peptide, EVLLRPGLHFR, designated TMSB4Y/A33, whose first amino acid was located 405 bp upstream of the TMSB4Y initiation codon. Analysis of the precursor frequency of CTL specific for recipient minor histocompatibility Ags in post-HSCT peripheral blood T cells revealed that a significant fraction of the total donor CTL response in this patient was directed against the TMSB4Y epitope. Tetramer analysis continued to detect TMSB4Y/A33-specific CD8(+) T cells at least up to 700 days post-HSCT. This finding underscores the in vivo immunological relevance of minor histocompatibility Ags derived from unconventional open reading frame products. 相似文献
79.
The role of WWP1-Gag interaction and Gag ubiquitination in assembly and release of human T-cell leukemia virus type 1 总被引:1,自引:0,他引:1 下载免费PDF全文
The PPPY motif in the matrix (MA) domain of human T-cell leukemia virus type 1 (HTLV-1) Gag associates with WWP1, a member of the HECT domain containing family of E3 ubiquitin ligases. Mutation of the PPPY motif arrests particle assembly at an early stage and abolishes ubiquitination of MA. Similar effects are seen when Gag is expressed in the presence of a truncated form of WWP1 that lacks the catalytically active HECT domain (C2WW). To understand the role of ubiquitination in budding, we mutated the four lysines in MA to arginines and identified lysine 74 as the unique site of ubiquitination. Virus-like particles produced by the K74R mutant did not contain ubiquitinated MA and showed a fourfold reduction in the release of infectious particles. Furthermore, the K74R mutation rendered assembly hypersensitive to C2WW inhibition; K74R Gag budding was inhibited at significantly lower levels of expression of C2WW compared with wild-type Gag. This finding indicates that the interaction between Gag and WWP1 is required for functions other than Gag ubiquitination. Additionally, we show that the PPPY− mutant Gag exerts a strong dominant-negative effect on the budding of wild-type Gag, further supporting the importance of recruitment of WWP1 to achieve particle assembly. 相似文献
80.
Nakajima Y Kobayashi K Yamagishi K Enomoto T Ohmiya Y 《Bioscience, biotechnology, and biochemistry》2004,68(3):565-570
A secreted luciferase from the marine ostracod, Vargula hilgendorfii, is a useful tool for gene expression assays in living mammalian cells. We have cloned the cDNA of a new secreted luciferase from the ostracod Cypridina noctiluca, which inhabits the coast of Japan. C. noctiluca luciferase consists of 553 amino acid residues with a molecular mass of 61,415 Da, as deduced from the nucleotide sequence. The homologies of nucleotide and amino acid sequences with V. hilgendorfii luciferase are 79.2% and 83.1%, respectively. C. noctiluca luciferase can expressed in and secreted from cultured mammalian cells. The characteristic properties of expressed C. noctiluca luciferase are similar to those of V. hilgendorfii luciferase. However, the activity of C. noctiluca luciferase in culture medium is much higher than that of V. hilgendorfii luciferase, suggesting that C. noctiluca luciferase is a highly potent reporter enzyme for real-time and continuous monitoring of gene expression in living cells. 相似文献