全文获取类型
收费全文 | 203篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
216篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 6篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 9篇 |
2009年 | 6篇 |
2008年 | 17篇 |
2007年 | 9篇 |
2006年 | 5篇 |
2005年 | 10篇 |
2004年 | 17篇 |
2003年 | 9篇 |
2002年 | 12篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1974年 | 4篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1970年 | 1篇 |
1967年 | 2篇 |
排序方式: 共有216条查询结果,搜索用时 0 毫秒
141.
George?Rutherford Milos?Tanurdzic Mitsuyasu?Hasebe Jo?Ann?BanksEmail author 《BMC plant biology》2004,4(1):6
Background
Ceratopteris richardii is a useful experimental system for studying gametophyte development and sexual reproduction in plants. However, few tools for cloning mutant genes or disrupting gene function exist for this species. The feasibility of systemic gene silencing as a reverse genetics tool was examined in this study. 相似文献142.
143.
The class B genes, which belong to the MADS-box gene family, play important roles in regulating the development of petals and stamens in flowering plants. To understand the molecular mechanisms of floral development in Agapanthus praecox ssp. orientalis (Agapanthaceae), we isolated and characterized the homologs of the Antirrhinum majus genes GLOBOSA and DEFICIENS in this plant. These were designated as ApGLO and ApDEF, respectively. ApGLO and ApDEF contain open reading frames that encode deduced protein with 210 and 214 amino acid residues, respectively. Phylogenetic analysis indicated that ApGLO and ApDEF belong to the monocot class B gene family. In situ hybridization experiments revealed that hybridization signals of ApGLO and ApDEF were observed in whorl 1 as well as in whorls 2 and 3. Moreover, the flowers of transgenic Arabidopsis plants that ectopically expressed ApGLO formed petal-like organs in whorl 1. These observations indicate that the flower developmental mechanism of Agapanthus follows the modified ABC model. 相似文献
144.
145.
Cryptochrome light signals control development to suppress auxin sensitivity in the moss Physcomitrella patens 总被引:12,自引:0,他引:12 下载免费PDF全文
The blue light receptors termed cryptochromes mediate photomorphological responses in seed plants. However, the mechanisms by which cryptochrome signals regulate plant development remain obscure. In this study, cryptochrome functions were analyzed using the moss Physcomitrella patens. This moss has recently become known as the only plant species in which gene replacement occurs at a high frequency by homologous recombination. Two cryptochrome genes were identified in Physcomitrella, and single and double disruptants of these genes were generated. Using these disruptants, it was revealed that cryptochrome signals regulate many steps in moss development, including induction of side branching on protonema and gametophore induction and development. In addition, the disruption of cryptochromes altered auxin responses, including the expression of auxin-inducible genes. Cryptochrome disruptants were more sensitive to external auxin than wild type in a blue light-specific manner, suggesting that cryptochrome light signals repress auxin signals to control plant development. 相似文献
146.
147.
Infection with the human immunodeficiency virus (HIV) is associated with an in vivo increase in B lymphocyte activation and immaturity 总被引:22,自引:0,他引:22
O Martínez-Maza E Crabb R T Mitsuyasu J L Fahey J V Giorgi 《Journal of immunology (Baltimore, Md. : 1950)》1987,138(11):3720-3724
The expression of phenotypic markers on B lymphocytes in patients with the acquired immune deficiency syndrome (AIDS), in human immunodeficiency virus (HIV) seropositive individuals, and in healthy seronegative donors was examined by two-color flow cytometry. Patients with AIDS and HIV-seropositive individuals showed an elevated percentage of B cells bearing an activation marker, the transferrin receptor, when compared with donors not infected with HIV. A decrease in the percentage of resting (Leu-8 positive) B cells was also seen in AIDS patients and HIV-seropositive individuals. An increased percentage of circulating, immature (CALLA-positive, CD10) B cells was seen in AIDS patients. These phenotypic changes were accompanied by an increased level of spontaneous IgG and IgM secretion, and increased cell size within the total B cell population and in some B cell subpopulations, in patients with AIDS and in HIV-seropositive people. These results demonstrate that phenotypic changes indicative of in vivo B cell activation and immaturity accompany the polyclonal production of Ig seen in HIV-infected individuals. 相似文献
148.
O Martínez-Maza R T Mitsuyasu S A Miles J V Giorgi D F Heitjan S A Sherwin J L Fahey 《Cellular immunology》1989,123(2):316-324
Twelve patients with the acquired immune deficiency syndrome (AIDS) and Kaposi's sarcoma were treated with recombinant human gamma-interferon (rIFN-gamma). A rapid, substantial increase in the fraction of HLA-DQ-positive monocytes was noted after treatment with rIFN-gamma. The rIFN-gamma-induced increase in monocyte HLA-DQ was seen throughout the course of treatment, with the percentage of HLA-DQ-positive monocytes dropping slightly following each week's treatment with rIFN-gamma and then rapidly increasing following the next course of treatment. Although the percentage of HLA-DR-positive monocytes was unchanged (HLA-DR was expressed on greater than 80% of monocytes prior to treatment), the density of HLA-DR on monocytes also increased following rIFN-gamma treatment. Following rIFN-gamma treatment, no changes were seen in CD3, CD4, CD8 T cell numbers, in T cell subset ratio (CD4/CD8), in Leu 7 or CD16 (Leu 11) cell number, in spontaneous Ig secretion, in PHA-induced in vitro proliferation, or in NK activity. These results indicate that exposure to rIFN-gamma in vivo led to the increased expression of class II antigens on monocytes in patients with AIDS. 相似文献
149.
Ryuji?TerayamaEmail authorView authors OrcID profile Yuya?Yamamoto Noriko?Kishimoto Mitsuyasu?Tabata Kotaro?Maruhama Seiji?Iida Tomosada?Sugimoto 《Neurochemical research》2016,41(11):2880-2889
Previous studies demonstrated that peripheral nerve injury induced excessive neuronal response and glial activation in the spinal cord dorsal horn, and such change has been proposed to reflect the development and maintenance of neuropathic pain states. The aim of this study was to examine neuronal excitability and glial activation in the spinal dorsal horn after peripheral nerve injury. We examined noxious heat stimulation-induced c-Fos protein-like immunoreactivity (Fos-LI) neuron profiles in fourth-to-sixth lumbar (L4–L6) level spinal dorsal horn neurons after fifth lumbar spinal nerve ligation (L5 SNL). Immunofluorescence labeling of OX-42 and GFAP was also performed in histological sections of the spinal cord. A significant increase in the number of Fos-LI neuron profiles in the spinal dorsal horn at the L4 level was found at 3 days after SNL, but returned to a level similar to that in sham-operated controls by 14 days after injury. As expected, a decrease in the number of Fos-LI neuron profiles in the spinal dorsal horn at the L5 level was found at 3 days after SNL. However, these profiles had reappeared in large numbers by 14 and 21 days after injury. Immunofluorescence labeling of OX-42 and GFAP indicated sequential activation of microglia and astrocytes in the spinal dorsal horn. We conclude that nerve injury causes differential changes in neuronal excitability in the spinal dorsal horn, which may coincide with glial activation. These changes may play a substantial role in the pathogenesis of neuropathic pain after peripheral nerve injury. 相似文献
150.
Souei Sekiya Teruyo Kaiho Syoichi Shirotake Hiroshi Iwasawa Noriyuki Inaba Makoto Kawata Koji Higaki Hideo Ishige Hiroyoshi Takamizawa Masako Minamihisamatsu Tsuguo Kuwata 《In vitro cellular & developmental biology. Plant》1983,19(6):489-494
Summary A human nongestational choriocarcinoma cell line of ovarian origin (IMa) was established in vitro. This cell line had been
subcultured serially more than 22 times over 18 months. Small polygonal cells with a prominent nucleus were dominant and a
sparsity of cytoplasmic organelles was an ultrastructural characteristic of the IMa cells. The production and secretion of
human chorionic gonadotropin and its subunits were identified by radioimmunoassay. The IMa cells were transplantable in the
hamster cheek pouch and the histological diagnosis was choriocarcinoma. A newly established ovarian choriocarcinoma cell line
can be considered useful for clarifying the biological differences between nongestational and gestational choriocarcinoma
cells.
This research was supported in part by a Grant-in-Aid for Cancer Research from both the Ministry of Health and Welfare and
the Ministry of Education, Science, and Culture of Japan. 相似文献