全文获取类型
收费全文 | 19023篇 |
免费 | 1397篇 |
国内免费 | 1229篇 |
出版年
2024年 | 43篇 |
2023年 | 255篇 |
2022年 | 546篇 |
2021年 | 927篇 |
2020年 | 569篇 |
2019年 | 808篇 |
2018年 | 798篇 |
2017年 | 563篇 |
2016年 | 836篇 |
2015年 | 1102篇 |
2014年 | 1355篇 |
2013年 | 1446篇 |
2012年 | 1678篇 |
2011年 | 1526篇 |
2010年 | 970篇 |
2009年 | 938篇 |
2008年 | 1047篇 |
2007年 | 978篇 |
2006年 | 799篇 |
2005年 | 685篇 |
2004年 | 534篇 |
2003年 | 520篇 |
2002年 | 437篇 |
2001年 | 343篇 |
2000年 | 302篇 |
1999年 | 290篇 |
1998年 | 164篇 |
1997年 | 158篇 |
1996年 | 155篇 |
1995年 | 117篇 |
1994年 | 84篇 |
1993年 | 71篇 |
1992年 | 110篇 |
1991年 | 82篇 |
1990年 | 69篇 |
1989年 | 52篇 |
1988年 | 43篇 |
1987年 | 44篇 |
1986年 | 38篇 |
1985年 | 51篇 |
1984年 | 8篇 |
1983年 | 17篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1974年 | 5篇 |
1969年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Je Yeong Ko Kyung Hyun Yoo Seon Ah Song Do Yeon Kim Hyun Kyung Kong Curie Ahn Han Woong Lee Duk-Hee Kang Goo Taeg Oh Jong Hoon Park 《The Journal of biological chemistry》2013,288(9):6488-6497
Cilia in ciliated cells consist of protruding structures that sense mechanical and chemical signals from the extracellular environment. Cilia are assembled with variety molecules via a process known as intraflagellar transport (IFT). What controls the length of cilia in ciliated cells is critical to understand ciliary disease such as autosomal dominant polycystic kidney disease, which involves abnormally short cilia. But this control mechanism is not well understood. Previously, multiple tubular cysts have been observed in the kidneys of max-interacting protein 1 (Mxi1)-deficient mice aged 6 months or more. Here, we clarified the relationship between Mxi1 inactivation and cilia disassembly. Cilia phenotypes were observed in kidneys of Mxi1-deficient mice using scanning electron microscopy to elucidate the effect of Mxi1 on renal cilia phenotype, and cilia disassembly was observed in Mxi1-deficient kidney. In addition, genes related to cilia were validated in vitro and in vivo using quantitative PCR, and Ift20 was selected as a candidate gene in this study. The length of cilium decreased, and p-ERK level induced by a cilia defect increased in kidneys of Mxi1-deficient mice. Ciliogenesis of Mxi1-deficient mouse embryonic fibroblasts (MEFs) decreased, and this abnormality was restored by Mxi1 transfection in Mxi1-deficient MEFs. We confirmed that ciliogenesis and Ift20 expression were regulated by Mxi1 in vitro. We also determined that Mxi1 regulates Ift20 promoter activity via Ets-1 binding to the Ift20 promoter. These results indicate that inactivating Mxi1 induces ciliary defects in polycystic kidney. 相似文献
942.
943.
Huan Yan Bo Peng Wenhui He Guocai Zhong Yonghe Qi Bijie Ren Zhenchao Gao Zhiyi Jing Mei Song Guangwei Xu Jianhua Sui Wenhui Li 《Journal of virology》2013,87(14):7977-7991
Human hepatitis B virus (HBV) and its satellite virus, hepatitis D virus (HDV), primarily infect humans, chimpanzees, or tree shrews (Tupaia belangeri). Viral infections in other species are known to be mainly restricted at the entry level since viral replication can be achieved in the cells by transfection of the viral genome. Sodium taurocholate cotransporting polypeptide (NTCP) is a functional receptor for HBV and HDV, and amino acids 157 to 165 of NTCP are critical for viral entry and likely limit viral infection of macaques. However, the molecular determinants for viral entry restriction in mouse NTCP (mNTCP) remain unclear. In this study, mNTCP was found to be unable to support either HBV or HDV infection, although it can bind to pre-S1 of HBV L protein and is functional in transporting substrate taurocholate; comprehensive swapping and point mutations of human NTCP (hNTCP) and mNTCP revealed molecular determinants restricting mNTCP for viral entry of HBV and HDV. Remarkably, when mNTCP residues 84 to 87 were substituted by human counterparts, mNTCP can effectively support viral infections. In addition, a number of cell lines, regardless of their species or tissue origin, supported HDV infection when transfected with hNTCP or mNTCP with residues 84 to 87 replaced by human counterparts, highlighting the central role of NTCP for viral infections mediated by HBV envelope proteins. These studies advance our understanding of NTCP-mediated viral entry of HBV and HDV and have important implications for developing the mouse model for their infections. 相似文献
944.
In January 1998, Taiwan promulgated the Law of the Republic of China (ROC) on the Territorial Sea and the Contiguous Zone and the Law of the Republic of China on the Exclusive Economic Zone (EEZ) and the Continental Shelf, both of which came into force on January 21, 1998. On June 26, 1998, China adopted the Law of the People's Republic of China on the Exclusive Economic Zone and the Continental Shelf, which is the most significant maritime legislation since its 1992 Law on the Territorial Sea and the Contiguous Zone. This article studies the recent maritime legislation developments in Mainland China and Taiwan, the differences and similarities between the two sets of laws, their implications for the Asia-Pacific region, and the potential challenges for the United States. 相似文献
945.
Yann-Huei Song 《Ocean Development & International Law》2013,44(2):150-177
This article examines the potential threat of marine pollution caused by offshore oil and gas development activities in the disputed areas of the South China Sea (SCS) and the Spratly Islands. After addressing the potential threat of marine pollution, it discusses the legal obligations and political commitment of the SCS littoral states regarding the protection of the marine environment in the area. The role that Taiwan can play in these matters is also examined. 相似文献
946.
Hongchao Wang Haiqin Chen Guangfei Hao Bo Yang Yun Feng Yu Wang Lu Feng Jianxin Zhao Yuanda Song Hao Zhang Yong Q. Chen Lei Wang Wei Chen 《Applied and environmental microbiology》2013,79(10):3225-3233
Mortierella alpina is a filamentous fungus commonly found in soil that is able to produce lipids in the form of triacylglycerols that account for up to 50% of its dry weight. Analysis of the M. alpina genome suggests that there is a phenylalanine-hydroxylating system for the catabolism of phenylalanine, which has never been found in fungi before. We characterized the phenylalanine-hydroxylating system in M. alpina to explore its role in phenylalanine metabolism and its relationship to lipid biosynthesis. Significant changes were found in the profile of fatty acids in M. alpina grown on medium containing an inhibitor of the phenylalanine-hydroxylating system compared to M. alpina grown on medium without inhibitor. Genes encoding enzymes involved in the phenylalanine-hydroxylating system (phenylalanine hydroxylase [PAH], pterin-4α-carbinolamine dehydratase, and dihydropteridine reductase) were expressed heterologously in Escherichia coli, and the resulting proteins were purified to homogeneity. Their enzymatic activity was investigated by high-performance liquid chromatography (HPLC) or visible (Vis)-UV spectroscopy. Two functional PAH enzymes were observed, encoded by distinct gene copies. A novel role for tetrahydrobiopterin in fungi as a cofactor for PAH, which is similar to its function in higher life forms, is suggested. This study establishes a novel scheme for the fungal degradation of an aromatic substance (phenylalanine) and suggests that the phenylalanine-hydroxylating system is functionally significant in lipid metabolism. 相似文献
947.
Bao-Le Zhang En Zhang Lu-Ping Pang Li-Xing Song Ya-Fei Li Bin Yu Hong-Min Liu 《Steroids》2013,78(12-13):1200-1208
Using dehydroepiandrosterone as the starting material, we have synthesized a series of steroid analogs possessing a D-ring fused with heterocycles which are pyridine, imidazo [2,1-b]thiazoles or substituted thiazole imines. All the final structures are first reported and identified by NMR and MS spectroscopys, the yields of these products are moderate to good and the reaction conditions are mild. The cytotoxicity of the synthesized compounds against EC-109(human esophageal carcinoma), EC-9706(human esophageal carcinoma), MGC-803(human gastric carcinoma) were investigated. 相似文献
948.
Mapping soybean aphid resistance genes in PI 567598B 总被引:1,自引:0,他引:1
Carmille Bales Guorong Zhang Menghan Liu Clarice Mensah Cuihua Gu Qijian Song David Hyten Perry Cregan Dechun Wang 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2013,126(8):2081-2091
The soybean aphid (Aphis glycines Matsumura) has been a major pest of soybean [Glycine max (L.) Merr.] in North America since it was first reported in 2000. Our previous study revealed that the strong aphid resistance of plant introduction (PI) 567598B was controlled by two recessive genes. The objective of this study was to locate these two genes on the soybean genetic linkage map using molecular markers. A mapping population of 282 F4:5 lines derived from IA2070 × E06902 was evaluated for aphid resistance in a field trial in 2009 and a greenhouse trial in 2010. Two quantitative trait loci (QTLs) were identified using the composite and multiple interval mapping methods, and were mapped on chromosomes 7 (linkage group M) and 16 (linkage group J), respectively. E06902, a parent derived from PI 567598B, conferred resistance at both loci. In the 2010 greenhouse trial, each of the two QTLs explained over 30 % of the phenotypic variation. Significant epistatic interaction was also found between these two QTLs. However, in the 2009 field trial, only the QTL on chromosome 16 was found and it explained 56.1 % of the phenotypic variation. These two QTLs and their interaction were confirmed with another population consisting of 94 F2:5 lines in the 2008 and 2009 greenhouse trials. For both trials in the alternative population, these two loci explained about 50 and 80.4 % of the total phenotypic variation, respectively. Our study shows that soybean aphid isolate used in the 2009 field trial defeated the QTL found on chromosome 7. Presence of the QTL on chromosome 16 conferred soybean aphid resistance in all trials. The markers linked to the aphid-resistant QTLs in PI 567598B or its derived lines can be used in marker-assisted breeding for aphid resistance. 相似文献
949.
950.
Jun Li Aiying Wang Fengmei Zhu Rui Xu Xiao Song Hu 《Indian journal of microbiology》2013,53(3):352-358
To clarify the mechanism of microbial inactivation by supercritical carbon dioxide (SCCO2), membrane damage of Rhodotorula mucilaginosa was investigated within specific pressure (10 Mpa), temperature (37 °C), and treatment time (10–70 min) ranges, including cell morphological structure, membrane permeability and fluidity. SEM and TEM observations showed morphological changes in the cell envelope and intracellular organization after SCCO2 treatment. Increase of membrane permeability was measured as increased uptake of the trypan blue dye with microscopy, and leakage of intracellular substances such as UV-absorbing materials and ions by determining the change of protein and electrical conductivity. The SCCO2 mediated reduction in CFU ml−1 was 0.5–1 log higher at 37 °C and 10 MPa for 60 min in Rose Bengal Medium containing 4 % sodium than a similar treatment in Rose Bengal Medium. Membrane fluidity analyzed by fluorescence polarization method using 1,6-diphenyl-1,3,5-hexatriene showed that the florescence polarization and florescence anisotropy of the SCCO2-treated cells were increased slightly and gently compared with the untreated cells. The correlation between membrane damage and death of cells under SCCO2 was clear, and the membrane damage was a key factor induced the inactivation of cells. 相似文献