全文获取类型
收费全文 | 5444篇 |
免费 | 408篇 |
国内免费 | 9篇 |
专业分类
5861篇 |
出版年
2023年 | 19篇 |
2022年 | 62篇 |
2021年 | 80篇 |
2020年 | 68篇 |
2019年 | 75篇 |
2018年 | 117篇 |
2017年 | 107篇 |
2016年 | 144篇 |
2015年 | 261篇 |
2014年 | 301篇 |
2013年 | 359篇 |
2012年 | 499篇 |
2011年 | 443篇 |
2010年 | 250篇 |
2009年 | 241篇 |
2008年 | 356篇 |
2007年 | 292篇 |
2006年 | 271篇 |
2005年 | 275篇 |
2004年 | 228篇 |
2003年 | 232篇 |
2002年 | 173篇 |
2001年 | 145篇 |
2000年 | 129篇 |
1999年 | 117篇 |
1998年 | 33篇 |
1997年 | 50篇 |
1996年 | 24篇 |
1995年 | 23篇 |
1994年 | 27篇 |
1993年 | 22篇 |
1992年 | 46篇 |
1991年 | 42篇 |
1990年 | 35篇 |
1989年 | 36篇 |
1988年 | 36篇 |
1987年 | 28篇 |
1986年 | 26篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 19篇 |
1982年 | 11篇 |
1979年 | 12篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 12篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1972年 | 8篇 |
1971年 | 8篇 |
排序方式: 共有5861条查询结果,搜索用时 0 毫秒
51.
52.
53.
Suman Kundu Talat Roome Ashish Bhattacharjee Kevin A. Carnevale Valentin P. Yakubenko Renliang Zhang Sung Hee Hwang Bruce D. Hammock Martha K. Cathcart 《Journal of lipid research》2013,54(2):436-447
Monocyte chemoattractant protein-1 (MCP-1)-induced monocyte chemotaxis is a major event in inflammatory disease. Our prior studies have demonstrated that MCP-1-dependent chemotaxis requires release of arachidonic acid (AA) by activated cytosolic phospholipase A2 (cPLA2). Here we investigated the involvement of AA metabolites in chemotaxis. Neither cyclooxygenase nor lipoxygenase pathways were required, whereas pharmacologic inhibitors of both the cytochrome-P450 (CYP) and the soluble epoxide hydrolase (sEH) pathways blocked monocyte chemotaxis to MCP-1. To verify specificity, we demonstrated that the CYP and sEH products epoxyeiscosatrienoic acids (EETs) and dihydroxyeicosatrienoic acids (DHETs), respectively, restored chemotaxis in the presence of the inhibitors, indicating that sEH-derived products are essential for MCP-1-driven chemotaxis. Importantly, DHETs also rescued chemotaxis in cPLA2-deficient monocytes and monocytes with blocked Erk1/2 activity, because Erk controls cPLA2 activation. The in vitro findings regarding the involvement of CYP/sEH pathways were further validated in vivo using two complementary approaches measuring MCP-1-dependent chemotaxis in mice. These observations reveal the importance of sEH in MCP-1-regulated monocyte chemotaxis and may explain the observed therapeutic value of sEH inhibitors in treatment of inflammatory diseases, cardiovascular diseases, pain, and even carcinogenesis. Their effectiveness, often attributed to increasing EET levels, is probably influenced by the impairment of DHET formation and inhibition of chemotaxis. 相似文献
54.
Ching-Hung Lee Yen-Wei Chen Yun-Tzu Huang Yih-Jiuan Pan Chien-Hsien Lee Shih-Ming Lin Lin-Kun Huang Yueh-Yu Lo Yu-Fen Huang Yu-Di Hsu Shih-Chung Yen Jenn-Kang Hwang Rong-Long Pan 《The Journal of membrane biology》2013,246(12):959-966
H+-translocating pyrophosphatase (H+-PPase, EC 3.6.1.1) plays an important role in acidifying vacuoles by transporting protons across membranes at the expense of pyrophosphate (PPi) hydrolysis. Vigna radiata H+-PPase (VrH+-PPase) contains 16 transmembrane helices (TMs). The hydrophobicity of TM3 is relatively lower than that of most other TMs, and the amino acids in this TM are highly conserved in plants. Furthermore, TM5 and -6, which are the core TMs involving in H+-PPase functions, are near TM3. It is thus proposed that TM3 is associated with H+-PPase activity. To address this possibility, site-directed mutagenesis was applied in this investigation to determine the role of TM3 in VrH+-PPase. Upon alanine/serine substitution, T138 and S142, whose side chains face toward the center TMs, were found to be involved in efficient proton transport. G149/S153 and G160/A164 pairs at the crucial termini of the two GxxxG-like motifs are indispensable in maintaining enzymatic activities and conformational stability. Moreover, stability in the vicinity surrounding G149 is pivotal for efficient expression. S153, M161 and A164 are critical for the K+-mediated stimulation of H+-PPase. Taken together, our results demonstrate that TM3 plays essential roles in PPi hydrolysis, proton transport, expression, and K+ stimulation of H+-PPase. 相似文献
55.
Ismail Bezirganoglu Shaw-Yhi Hwang Tony J. Fang Jei-Fu Shaw 《Plant Cell, Tissue and Organ Culture》2013,112(2):227-237
The oriental melon (Cucumis melo L. var. makuwa cv. ‘Silver Light’) is an important fruit crop in the tropical and subtropical regions. However, oriental melon production is severely decreased by fungal diseases. In this study, antifungal protein (AFP) and chitinase (CHI) fusion genes were introduced into oriental melons to control fungal diseases caused by Rhizoctonia solani and Fusarium oxysporum. Transformation of oriental melon (Cucumis melo L. var. makuwa cv. ‘Silver Light’) with Agrobacterium tumefaciens strain LBA4404 containing antifungal protein (AFP) and chitinase (CHI) fusion genes under the control of the cauliflower mosaic virus (CaMV) 35S promoter and neomycin phosphotransferase (nptII) gene as a selectable marker was performed. Cotyledon explants of oriental melon were inoculated by Agrobacterium suspensions with pBI121–AFP–CHI and cultured in a regeneration medium. After regeneration, genomic DNA polymerase chain reaction (PCR) was conducted to confirm the presence of putative transgenic shoots. Southern blot analysis confirmed that the AFP–CHI fusion gene was incorporated into the genomic DNA of the PCR-positive lines. RT-PCR analysis showed that the AFP–CHI fusion gene was expressed in the individual transgenic lines. Western blot analysis revealed the accumulation of CHI protein in leaves. A segregation analysis of the T1 generation confirmed the inheritance of the transgene. Our results demonstrated that the AFP–CHI fusion gene was effective in protecting the transgenic melon plants against fungal disease caused by Rhizoctonia solani and Fusarium oxysporum. 相似文献
56.
H. S. Yoon Y. K. An J. H. Hwang H. S. Lim W. K. Lee K. H. Han S. H. Lee S. D. Choi 《Zeitschrift fur angewandte Ichthyologie》2013,29(2):468-469
Length–weight relationships were estimated for 14 species belonging to 13 fish families from the Suer River estuary, Korea. These 14 species are: Callionymus valenciennei, Konosirus punctatus, Conger myriaster, Cynoglossus joyneri, Tribolodon hakonensis, Thryssa hamiltonii, Acanthogobius flavimanus, Paratrypauchen microcephalus, Hexagrammos agrammus, Nuchequula nuchalis, Pseudopleuronectes yokohamae, Pennahia argentata, Sillago japonica and Takifugu niphobles. Between April 2009 and January 2010, samples were caught by commercial trawl net at depths of <20 m. Estimates for parameter b of the length–weight relationship (W = aLb) ranged between 2.510 and 3.149. 相似文献
57.
Keun Sik Baik Yeoung Min Hwang Jong-Soon Choi Joseph Kwon Chi Nam Seong 《Antonie van Leeuwenhoek》2013,104(6):1143-1150
A motile, curved to twisted rod-shaped aerobic bacterium, designated strain 04SU4-PT, was isolated from freshwater collected from the Woopo wetland (Republic of Korea). Cells were observed to be Gram-stain negative, catalase negative and oxidase positive. The major fatty acids (>10 % of the total) were identified as C19:0 ω8c cyclo (24.6 %), C16:0 (24.3 %) and C18:1 ω7c (13.1 %). The DNA G+C content was determined to be 71.5 mol%. The major polar lipids were identified as phosphatidylglycerol, phosphatidylethanolamine, one unknown phospholipid and one unknown aminolipid. The major ubiquinone was determined to be Q-10. A phylogenetic tree based on 16S rRNA gene sequences showed that strain 04SU4-PT forms an evolutionary lineage within the genus Dongia and its nearest neighbour is Dongia mobilis LM22T (98.0 % sequence similarity). Genomic DNA–DNA hybridization of stain 04SU4-PT with D. mobilis LM22T showed relatedness of only 34.2 %. The phenotypic characteristics indicate the strain 04SU4-PT can be distinguished from the sole member of the genus Dongia. On the basis of the data presented in this study, strain 04SU4-PT represents a novel species, for which the name Dongia rigui is proposed. The type strain is 04SU4-PT (KCTC 23341T = JCM 17521T). 相似文献
58.
Andrew Hollingworth Seongmin Hwang 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2013,368(1628)
We examined the conditions under which a feature value in visual working memory (VWM) recruits visual attention to matching stimuli. Previous work has suggested that VWM supports two qualitatively different states of representation: an active state that interacts with perceptual selection and a passive (or accessory) state that does not. An alternative hypothesis is that VWM supports a single form of representation, with the precision of feature memory controlling whether or not the representation interacts with perceptual selection. The results of three experiments supported the dual-state hypothesis. We established conditions under which participants retained a relatively precise representation of a parcticular colour. If the colour was immediately task relevant, it reliably recruited attention to matching stimuli. However, if the colour was not immediately task relevant, it failed to interact with perceptual selection. Feature maintenance in VWM is not necessarily equivalent with feature-based attentional selection. 相似文献
59.
In-Kyu Hwang Shuichi Kaminogawa Kunio Yamauchi 《Bioscience, biotechnology, and biochemistry》2013,77(12):3049-3053
Some kinetic properties of a dipeptidase purified from a cell-free extract of Streptococcus cremoris H 61 were investigated. The Km values of this enzyme for various dipeptides were divided into 3 groups. Group 1 comprised mainly of neutral dipeptides, such as Leu-Gly, Leu-Leu and Leu-Ala, which had relatively low Km values (in the range 4.0-6.6 mm). Group 2 consisted of dipeptides with aromatic large amino acids either at the N- or C-terminal positions, like Leu-Phe, Phe-Ala and Leu-Tyr, which had very low Km values (in the range 1.0-2.4 mm). Group 3 was made up by dipeptides with acidic or basic amino acids at the N-terminals; His-Ala and Glu-Val were typical of this group. These had very high Km values (in the range 10–20 mm). Substantial substrate competition was found to exist in the presence of His-Ala. Bestatin inhibited the enzyme competitively with Leu-Gly and was found to have an apparent Ki value of 3.0 × 10?8 m for the enzyme. Further, the enzyme was completely inhibited by EDTA at a concentration of 2.0 × 10?5 m. On the other hand, once the activity was inhibited by EDTA, it could be restored by Co2+ and Zn2+ in the acidic pH side, and by Ca2+ and Mn2+ in the alkaline pH side. 相似文献
60.
CongXin Dai Feng Cai Kuo Chu Hwang YongMao Zhou ZiZhu Zhang XiaoHai Liu SiHai Ma YaKun Yang Yong Yao Ming Feng XinJie Bao GuiLin Li JunJi Wei YongHui Jiao ZhenQing Wei WenBin Ma RenZhi Wang 《中国科学:生命科学英文版》2013,56(2):163-173
Invasive nonfunctional pituitary adenomas (NFPAs) are difficult to completely resect and often develop tumor recurrence after initial surgery. Currently, no medications are clinically effective in the control of NFPA. Although radiation therapy and radiosurgery are useful to prevent tumor regrowth, they are frequently withheld because of severe complications. Boron neutron capture therapy (BNCT) is a binary radiotherapy that selectively and maximally damages tumor cells without harming the surrounding normal tissue. Folate receptor (FR)-targeted boron-10 containing carbon nanoparticles is a novel boron delivery agent that can be selectively taken up by FR-expressing cells via FR-mediated endocytosis. In this study, FR-targeted boron-10 containing carbon nanoparticles were selectively taken up by NFPAs cells expressing FR but not other types of non-FR expressing pituitary adenomas. After incubation with boron-10 containing carbon nanoparticles and following irradiation with thermal neutrons, the cell viability of NFPAs was significantly decreased, while apoptotic cells were simultaneously increased. However, cells administered the same dose of FR-targeted boron-10 containing carbon nanoparticles without neutron irradiation or received the same neutron irradiation alone did not show significant decrease in cell viability or increase in apoptotic cells. The expression of Bcl-2 was down-regulated and the expression of Bax was up-regulated in NFPAs after treatment with FR-mediated BNCT. In conclusion, FR-targeted boron-10 containing carbon nanoparticles may be an ideal delivery system of boron to NFPAs cells for BNCT. Furthermore, our study also provides a novel insight into therapeutic strategies for invasive NFPA refractory to conventional therapy, while exploring these new applications of BNCT for tumors, especially benign tumors. 相似文献