全文获取类型
收费全文 | 2368篇 |
免费 | 130篇 |
出版年
2022年 | 12篇 |
2021年 | 27篇 |
2020年 | 13篇 |
2019年 | 28篇 |
2018年 | 22篇 |
2017年 | 24篇 |
2016年 | 39篇 |
2015年 | 82篇 |
2014年 | 77篇 |
2013年 | 171篇 |
2012年 | 135篇 |
2011年 | 120篇 |
2010年 | 87篇 |
2009年 | 87篇 |
2008年 | 147篇 |
2007年 | 142篇 |
2006年 | 116篇 |
2005年 | 125篇 |
2004年 | 137篇 |
2003年 | 131篇 |
2002年 | 104篇 |
2001年 | 68篇 |
2000年 | 62篇 |
1999年 | 46篇 |
1998年 | 19篇 |
1997年 | 23篇 |
1996年 | 18篇 |
1995年 | 22篇 |
1994年 | 21篇 |
1993年 | 23篇 |
1992年 | 41篇 |
1991年 | 40篇 |
1990年 | 29篇 |
1989年 | 32篇 |
1988年 | 21篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 19篇 |
1984年 | 21篇 |
1983年 | 10篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 13篇 |
1977年 | 16篇 |
1975年 | 7篇 |
1974年 | 13篇 |
1973年 | 7篇 |
1972年 | 5篇 |
排序方式: 共有2498条查询结果,搜索用时 15 毫秒
101.
Seiya Sato Hiroaki Itamochi Nao Oumi Youhei Chiba Tetsuro Oishi Muneaki Shimada Shinya Sato Jun Chikumi Michiko Nonaka Akiko Kudoh Hiroaki Komatsu Tasuku Harada Toru Sugiyama 《Human cell》2016,29(4):181-187
A new cell line of human ovarian clear cell carcinoma (CCC), TU-OC-2, was established and characterized. The cells were polygonal in shape, grew in monolayers without contact inhibition and were arranged in islands like pieces of a jigsaw puzzle. The chromosome numbers ranged from 41 to 96. A low rate of proliferation was observed and the doubling time was 37.5 h. The IC50 values of cisplatin, 7-ethyl-10-hydroxycamptothecin (SN38), which is an active metabolite of camptothecin, and paclitaxel were 7.7 μM, 17.7 nM and 301 nM, respectively. The drug sensitivity assay indicated that TU-OC-2 was sensitive to SN38, but resistant to cisplatin and paclitaxel. Mutational analysis revealed that TU-OC-2 cells have no mutations of PIK3CA in exons 9 and 20 and of TP53 in exons 4–9. We observed the loss of ARID1A protein expression in TU-OC-2 cells by western blot analysis and in the original tumor tissue by immunohistochemistry. This cell line may be useful for studying the chemoresistant mechanisms of CCC and exploring novel therapeutic targets such as the ARID1A-related signaling pathway. 相似文献
102.
Murakami Shinsuke Nakatani Jun Nakajima Kenichi Amasawa Eri Ii Ryota Hayashi Kiyotada Yoshikawa Naoki Daigo Ichiro Kishita Yusuke Ihara Tomohiko Shobatake Koichi Kudoh Yuki Motoshita Masaharu Kanemoto Keiichiro Hara Minako Kashiwagi Aiichiro Hashimoto Seiji Shigetomi Yosuke Kanzaki Masayuki Kikuchi Yasunori Ohno Hajime Fukushima Yasuhiro 《The International Journal of Life Cycle Assessment》2019,24(8):1544-1552
The International Journal of Life Cycle Assessment - 相似文献
103.
104.
Oncostatin M induces upregulation of claudin-2 in rodent hepatocytes coinciding with changes in morphology and function of tight junctions 总被引:1,自引:0,他引:1
Imamura M Kojima T Lan M Son S Murata M Osanai M Chiba H Hirata K Sawada N 《Experimental cell research》2007,313(9):1951-1962
In rodent livers, integral tight junction (TJ) proteins claudin-1, -2, -3, -5 and -14 are detected and play crucial roles in the barrier to keep bile in bile canaculi away from the blood circulation. Claudin-2 shows a lobular gradient increasing from periportal to pericentral hepatocytes, whereas claudin-1 and -3 are expressed in the whole liver lobule. Although claudin-2 expression induces cation-selective channels in tight junctions of epithelial cells, the physiological functions and regulation of claudin-2 in hepatocytes remain unclear. Oncostatin M (OSM) is a multifunctional cytokine implicated in the differentiation of hepatocytes that induces formation of E-cadherin-based adherens junctions in fetal hepatocytes. In this study, we examined whether OSM could induce expression and function of claudin-2 in rodent hepatocytes, immortalized mouse and primary cultured proliferative rat hepatocytes. In the immortalized mouse and primary cultured proliferative rat hepatocytes, treatment with OSM markedly increased mRNA and protein of claudin-2 together with formation of developed networks of TJ strands. The increase of claudin-2 enhanced the paracellular barrier function which depended on molecular size. The increase of claudin-2 expression induced by OSM in rodent hepatocytes was regulated through distinct signaling pathways including PKC. These results suggest that expression of claudin-2 in rodent hepatocytes may play a specific role as controlling the size of paracellular permeability in the barrier to keep bile in bile canaculi. 相似文献
105.
106.
107.
Sakata E Yamaguchi Y Miyauchi Y Iwai K Chiba T Saeki Y Matsuda N Tanaka K Kato K 《Nature structural & molecular biology》2007,14(2):167-168
Although cullin-1 neddylation is crucial for the activation of SCF ubiquitin E3 ligases, the underlying mechanisms for NEDD8-mediated activation of SCF remain unclear. Here we demonstrate by NMR and mutational studies that NEDD8 binds the ubiquitin E2 (UBC4), but not NEDD8 E2 (UBC12). Our data imply that NEDD8 forms an active platform on the SCF complex for selective recruitment of ubiquitin-charged E2s in collaboration with RBX1, and thereby upregulates the E3 activity. 相似文献
108.
Osamu Miura Gen Kanaya Shizuko Nakai Hajime Itoh Satoshi Chiba 《International journal for parasitology》2019,49(13-14):1023-1028
Trematode parasites have complex life cycles and use a variety of host species across different trophic levels. Thus, they can be used as indicators of disturbance and recovery of coastal ecosystems. Estuaries on the Pacific coast of northeastern Japan were heavily affected by the 2011 Tohoku earthquake tsunami. To evaluate the effect of the tsunami on the trematode community, we examined trematodes in the mud snail, Batillaria attramentaria, at five study sites (three sites severely exposed to the tsunami and two sites sheltered from the tsunami) in Sendai Bay for 2 years prior to and 8 years after the tsunami. While the trematode prevalence decreased at all study sites, the species richness decreased only at the sites exposed to the tsunami. Although parasitism increased over the study period post-tsunami, the community had not fully recovered 8 years after the event. Trematode community structure has changed every year since the tsunami and has not stabilised. This could be explained by the alteration of first and second intermediate host communities. Our study suggests that it will take more time for the recovery of the trematode community and the associated coastal ecosystem in the Tohoku region. 相似文献
109.
Photosystem I (PSI) and photosystem II (PSII) play key roles in photoinduced electron-transfer reaction in oxygenic photosynthesis. Assemblies of these PSs can be initiated by illumination of the etiolated seedlings (greening). The study aimed to identify specific fluorescence spectral components relevant to PSI and PSII assembly intermediates emerging in greening seedlings of Zea mays, a typical C4 plant. The different PSII contents between the bundle sheath (BS) and mesophyll (M) cells were utilized to spectrally isolate the precursors to PSI and PSII. The greening Zea mays leaf thin sections were observed with the cryogenic microscope combined with a spectrometer. With the aid of the singular-value decomposition analysis, we could identify four independent fluorescent species, SAS677, SAS685, SAS683, and SAS687, named after their fluorescence peak wavelengths. SAS677 and SAS685 are the dominant components after the 30-minute greening, and the distributions of these components showed no clear differences between M and BS cells, indicating immature cell differentiation in this developing stage. On the other hand, the 1-hour greening resulted in reduced distributions of SAS683 in BS cells leading us to assign this species to PSII precursors. The 2-hour greening induced the enrichment of SAS687 in BS cells suggesting its PSI relevance. Similarity in the peak wavelengths of SAS683 and the reported reaction center of PSII implied their connection. SAS687 showed an intense sub-band at around 740 nm, which can be assigned to the emission from the red chlorophylls specific to the mature PSI. 相似文献
110.
Yasunori Tome Tasuku Kiyuna Fuminari Uehara Michael Bouvet Hiroyuki Tsuchiya Fuminori Kanaya Robert M. Hoffman 《Journal of cellular biochemistry》2019,120(1):283-289
Human osteosarcoma 143B cells were previously stably transfected with an αv integrin green flourescent protein (GFP) vector. 143B cells expressing αv integrin-GFP were transplanted orthotopically in the tibia of transgenic nude mice ubiquitously expressing red fluorescent protein (RFP). The primary tumors acquired RFP-expressing stroma and were passaged orthotopically in the tibia in noncolored nude mice, which maintained the RFP stroma. The interaction of αv integrin-GFP expression in 143B cells with RFP-expressing host stromal cells was observed by confocal microscopy using the Olympus FV1000. Collagen fibers were imaged simultaneously in reflectance mode. The RFP-expressing stroma included cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) which persisted even 3 weeks after passage to nontransgenic nude mice. CAFs expressing RFP were aligned between collagen fibers and cancer cells expressing αv integrin-GFP. Six weeks after transplantation, pulmonary metastases expressing αv integrin-GFP could be identified. TAMs expressing RFP accompanied metastasized osteosarcoma cells expressing αv integrin-GFP in the lung. The current study demonstrates the importance of αv integrin interaction with stromal elements in osteosarcoma. 相似文献