全文获取类型
收费全文 | 2685篇 |
免费 | 147篇 |
国内免费 | 10篇 |
出版年
2022年 | 15篇 |
2021年 | 24篇 |
2020年 | 10篇 |
2019年 | 19篇 |
2018年 | 17篇 |
2017年 | 29篇 |
2016年 | 46篇 |
2015年 | 52篇 |
2014年 | 59篇 |
2013年 | 155篇 |
2012年 | 103篇 |
2011年 | 144篇 |
2010年 | 74篇 |
2009年 | 87篇 |
2008年 | 139篇 |
2007年 | 145篇 |
2006年 | 121篇 |
2005年 | 152篇 |
2004年 | 123篇 |
2003年 | 137篇 |
2002年 | 126篇 |
2001年 | 102篇 |
2000年 | 81篇 |
1999年 | 87篇 |
1998年 | 32篇 |
1997年 | 37篇 |
1996年 | 24篇 |
1995年 | 25篇 |
1994年 | 29篇 |
1993年 | 32篇 |
1992年 | 47篇 |
1991年 | 45篇 |
1990年 | 52篇 |
1989年 | 51篇 |
1988年 | 48篇 |
1987年 | 37篇 |
1986年 | 47篇 |
1985年 | 39篇 |
1984年 | 24篇 |
1983年 | 33篇 |
1982年 | 15篇 |
1981年 | 22篇 |
1980年 | 19篇 |
1979年 | 24篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1966年 | 7篇 |
排序方式: 共有2842条查询结果,搜索用时 78 毫秒
51.
52.
Structural proteins and the characteristics of infectious flacherie virus (IFV) purified from the silkworm, Bombyx mori, are described. The purified IFV had four major structural proteins, which were detected only in high concentration gels of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and a few minor ones. Molecular weights of the major proteins were 35,200 (VP 1), 33,000 (VP 2), 31,200 (VP 3), and 11,600 (VP 4), and numbers per virion were 62, 57, 54, and 31, respectively. Amino acid compositions of VP 1, VP 2, and VP 3 were similar to each other but that of VP 4 was somewhat different. By isoelectric focusing and two-dimensional electrophoresis, high resolution of the structural proteins was obtained with silver staining. The isoelectric points of the four major proteins were determined as 7.7(VP 1), 6.7(VP 2), 4.8(VP 3), and 5.5(VP 4). This work is the first report on insect picornaviruses that presents some discriminative properties of each viral protein that was compared to those of mammalian picornaviruses. 相似文献
53.
M Sugimoto Y Nakanishi M Otokawa N Uchida T Yasuda H Sato Y Sato 《Journal of immunology (Baltimore, Md. : 1950)》1983,130(6):2767-2774
The effect of highly purified leukocytosis (lymphocytosis)-promoting factor (LPF) of Bordetella pertussis on physical lymphocyte and reticuloepithelial (RE) cell association was studied in an in vitro thymus model. First, a simplified in vitro system to assess the lympho-RE-cell association was developed. A completely confluent layer of thymic RE cells was formed by cultivating trypsinized thymus cell suspensions from 2- to 7-day-old mice. When thymic lymphoid cells were seeded on this cell layer and cultivated overnight, a significant proportion of them were found underneath the RE cell layer. This physical lympho-RE-cell association was quantitated by counting the lymphoid cells underneath the RE cell layers. Second, the effect of LPF on this physical lympho-RE-cell association phenomenon was investigated. Addition of LPF to the culture markedly inhibited the formation of the lympho-RE-cell complex; that is, it inhibited the infiltration of lymphoid cells under the RE cell layer. LPF rendered a nearly maximal level of inhibitory effect at a dose of 0.1 ng/ml. Furthermore, LPF enhanced the liberation of lymphoid cells from preformed lympho-RE-cell complexes. On the other hand, LPF had no direct cytotoxic effect on lymphoid cells at doses below 1 microgram/ml. In order to investigate whether LPF produced the effect by acting on lymphoid cells, RE cells, or both, the following experiments were performed. When lymphoid cells were pretreated with LPF and added to normal RE cell layers, the lympho-RE-cell association was maximally inhibited above the dose of 1 ng/ml. Treatment of these LPF-treated lymphoid cells with anti-LPF antibodies failed to abrogate the effect of LPF. When RE cell layers were similarly pretreated with LPF and were cultivated with normal lymphoid cells, however, much higher doses of LPF, above 100 ng/ml, were required for maximal inhibition. Furthermore, treatment of these LPF-treated RE cells with anti-LPF antibodies abrogated the effect of LPF. Therefore, the apparent effect of LPF on RE cells was considered to be due to the carry-over by RE cells of LPF, which should directly act on lymphoid cells at extremely low doses. On the basis of these results, it was concluded that LPF acted directly on lymphoid cells without mediation of RE cells. These in vitro results appear to parallel the effects of LPF in vivo, where it induces a depletion of cells in the thymus. The model may be useful to study this phenomenon and the concomitant accumulation of blood lymphocytes. 相似文献
54.
Extracellular matrix during laminar pattern formation of neocortex in normal and reeler mutant mice 总被引:6,自引:0,他引:6
S Nakanishi 《Developmental biology》1983,95(2):305-316
The spatial and temporal distribution of extracellular matrix, which occupied the large extracellular spaces in the developing cerebral cortex, was studied during pre- and perinatal ontogenesis of normal and reeler mutant mice. Colloidal iron-staining material was localized principally in the marginal zone and subplate of normal mice, whereas in reeler mutants, most of the material was found in the outer layers of the cortex. Patterns of extracellular matrix localization in both genotypes followed the laminar pattern formation of cerebral cortex architecture. Histochemical ultrastructural visualization of this extracellular matrix and its susceptibility to enzymatic treatment suggested that the major components are glycosaminoglycans. Their possible role in relation to afferent axon targeting is discussed. 相似文献
55.
56.
The treatment of neuromuscular junctions with phosphomolybdic acid (PMA) and silicotungstic acid (STA) heteropolyanions permits the visualization of electron dense precipitates in the synaptic vesicles of the cholinergic motor nerve terminals. At the light microscopic level, the uncolored molybdenum salt is visualized after reduction to molybdenum blue. The blue coloration is confined to the nerve terminals. Since PMA and STA are known as strong precipitating agents of quaternary ammonium compounds (cations) it is supposed that they have insolubilized in situ the acetylcholine (Ach) of the synaptic vesicles by means of a rapid ionic interaction. Furthermore, in spite of the strong acidity of PMA and STA solutions, the ultrastructure of the treated tissue is not significantly altered but on the contrary seems to be well preserved. The ionic insolubilization of Ach, added to the good preservation of the ultrastructure prompted us to use the term "ionic fixation". 相似文献
57.
58.
59.
Noriaki Inamura Saburo Sone Akio Okubo Eiji Kunishige Mie Nakanishi Takeshi Ogura 《Cancer immunology, immunotherapy : CII》1989,28(3):164-170
Summary Human blood monocytes were isolated by counter-flow centrifugal elutriation from healthy donors and these noncytotoxic monocytes were rendered tumoricidal to allogeneic melanoma (A375) cells by activation with a synthetic acyltripeptide (FK-565), as assessed by measuring release of [125I]iododeoxyuridine in 72 h. When monocytes were treated with FK-565 for 16 h, and then fixed with paraformaldehyde, they showed cytotoxicity to A375 melanoma cells. The fixed-monocyte-mediated cytotoxicity to A375 cells was induced by the synergistic actions of FK-565 and recombinant interferon- (rIFN-), but not other cytokines [rIFN-A, rIFN-, tumor necrosis factor (TNF), interleukin (IL)-2, -3 and -6]. For synergistic activation of monocytes with induction of a membrane-associated antitumor monokine, the monocytes had to be incubated first with rIFN- and then with FK-565. FK-565 also acted synergistically with rIFN- to stimulate monocytes to produce membrane-associated IL-1 activity, which induced C3H/HeJ thymocyte blastogenesis in response to phytohemagglutinin P. The tumoricidal and thymocytestimulating activities of the fixed monocytes were almost completely inhibited by a specific anti-(IL-1) antiserum, but not by a specific anti-(IL-1) antiserum or monoclonal anti-TNF antibody. These results suggest that membrane-associated IL-1 of human blood monocytes can be induced by two activation signals (rIFN- then FK-565) at their suboptimal concentrations.Abbreviations IL
interleukin
- IFN
interferon
- TNF
tumor necrosis factor 相似文献
60.
Norimichi Kan Takashi Okino Masaki Nakanishi Kohei Satoh Kazuhisa Ohgaki Takayoshi Tobe 《Cancer immunology, immunotherapy : CII》1989,28(4):260-266
Summary The synergistic antitumor effect of interleukin-2(IL-2)-cultured tumor-bearer spleen cells (cultured lymphocytes) and immune fresh spleen cells was examined. Tumor-bearer cultured lymphocytes were obtained by culturing BALB/c spleen cells from syngeneic MOPC104E-tumor-bearing mice for 11 days with crude IL-2 and a soluble tumor extract. These cultured lymphocytes had weak antitumor activity when transferred i.p. into tumor-bearing mice that had been inoculated i.p. with 105 tumor cells 5 days previously. Immune fresh spleen cells, obtained from mice in complete remission after the treatment with cyclophosphamide, also had weak antitumor activity when transferred at the same schedule. The cultured cells and the fresh cells, mixed together before transfer, significantly augmented the therapeutic effect. At least 1×107 tumor-bearer cultured lymphocytes and 4×107 immune cells were needed for the synergistic effect. A tumor-specific combination was needed for both cultured and fresh cells. The effective subpopulation of tumor-bearer cultured lymphocytes was a cytotoxic one from an Lyt2+ precursor, and that of the immune fresh spleen cells was noncytotoxic, Lytl+ and Lyt2+ T-cells.A similar synergistic effect was also observed during in vitro coculture of tumor-bearer and immune cells. Cytotoxicity, as assessed by the 51Cr-release test, of tumor-bearer IL-2-cultured lymphocytes was maintained most effectively after 3 or 4 days of culture without IL-2 when the lymphocytes were cocultured with immune fresh spleen cells and tumor cells. 相似文献