全文获取类型
收费全文 | 1687篇 |
免费 | 96篇 |
出版年
2022年 | 13篇 |
2021年 | 28篇 |
2020年 | 4篇 |
2019年 | 25篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 35篇 |
2015年 | 48篇 |
2014年 | 75篇 |
2013年 | 74篇 |
2012年 | 110篇 |
2011年 | 108篇 |
2010年 | 60篇 |
2009年 | 55篇 |
2008年 | 135篇 |
2007年 | 98篇 |
2006年 | 100篇 |
2005年 | 93篇 |
2004年 | 111篇 |
2003年 | 108篇 |
2002年 | 117篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 24篇 |
1998年 | 30篇 |
1997年 | 18篇 |
1996年 | 16篇 |
1995年 | 17篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1971年 | 3篇 |
1969年 | 2篇 |
排序方式: 共有1783条查询结果,搜索用时 15 毫秒
141.
142.
Hiroko Yamada Kazuaki Takahashi Olline Lim Somana Svay Channarena Chuon Sirany Hok Son Huy Do Mayumi Fujimoto Tomoyuki Akita Noboru Goto Keiko Katayama Masahiro Arai Junko Tanaka 《PloS one》2015,10(8)
Hepatitis E virus (HEV) is a growing public health problem in many countries. In this study, we investigated HEV seroprevalence among the general population in the Siem Reap province, Cambodia, and performed HEV genetic analysis with the aim to develop an HEV prevention strategy. This seroepidemiological cross-sectional study conducted from 2010 to 2014 included 868 participants from four different locations in Siem Reap province, Cambodia. They answered questionnaires and provided blood samples for the analysis of hepatitis virus infections. Among the participants (360 men and 508 women; age range, 7–90 years), the prevalence of anti-HEV IgG was 18.4% (95% confidence interval: 15.9–21.0); HEV RNA was detected in two participants (0.23%) and was classified as genotype 3 and 4. Full-length genome of the genotype 4 isolate, CVS-Sie10, was sequenced; it contained 7,222 nucleotides and three ORFs and demonstrated high sequence identity with the swine China isolates swGX40 (95.57%), SS19 (94.37%), and swDQ (91.94%). Multivariate logistic regression analysis revealed that men, elderly people, and house workers were risk groups significantly associated with the positivity for anti-HEV IgG. This is the first report on the detection of HEV genotype 4 in humans in Cambodia and on the complete genome sequence of HEV genotype 4 from this country. Our study demonstrates that new HEV infection cases occur frequently among the general population in Cambodia, and effective preventive measures are required. 相似文献
143.
Takaharu Yamamoto Junko Mochida Jun Kadota Miyoko Takeda Erfei Bi Kazuma Tanaka 《Molecular biology of the cell》2010,21(7):1237-1252
The assembly of filamentous actin is essential for polarized bud growth in budding yeast. Actin cables, which are assembled by the formins Bni1p and Bnr1p, are thought to be the only actin structures that are essential for budding. However, we found that formin or tropomyosin mutants, which lack actin cables, are still able to form a small bud. Additional mutations in components for cortical actin patches, which are assembled by the Arp2/3 complex to play a pivotal role in endocytic vesicle formation, inhibited this budding. Genes involved in endocytic recycling were also required for small-bud formation in actin cable-less mutants. These results suggest that budding yeast possesses a mechanism that promotes polarized growth by local recycling of endocytic vesicles. Interestingly, the type V myosin Myo2p, which was thought to use only actin cables to track, also contributed to budding in the absence of actin cables. These results suggest that some actin network may serve as the track for Myo2p-driven vesicle transport in the absence of actin cables or that Myo2p can function independent of actin filaments. Our results also show that polarity regulators including Cdc42p were still polarized in mutants defective in both actin cables and cortical actin patches, suggesting that the actin cytoskeleton does not play a major role in cortical assembly of polarity regulators in budding yeast. 相似文献
144.
145.
Manabu Yamada Mitsuji Yamashita Takuya Suyama Junko Yamashita Kazuhide Asai Taishi Niimi Nobuhisa Ozaki Michio Fujie Kasthuraiah Maddali Satoki Nakamura Kazunori Ohnishi 《Bioorganic & medicinal chemistry letters》2010,20(19):5943-5946
4-Bromo-3,4-dimethyl-1-phenyl-2-phospholene 1-oxide (3c) was first synthesized from 3,4-dimethyl-1-phenyl-2-phospholene 1-oxide (2c) by a bromo-radical substitution reaction occurred at C-4 position by N-bromosuccinimide and 2,2′-azobisisobutyronitrile. The novel phospha sugar analogue 3c exerted high anti-proliferative effect on U937 cells evaluated by MTT in vitro methods and was much more efficient than that of Gleevec®, which is known as a molecule targeting chemotherapeutical agent. The substitution of 2-phospholenes at C-3 and C-4 position with methyl groups as well as 4-bromo substituent suggests a good anti-proliferative effect. 相似文献
146.
Claudin-16 is involved in the paracellular reabsorption of Mg2+ in the thick ascending limb of Henle. Little is known about the mechanism regulating the tight junctional localization of claudin-16. Here, we examined the effect of Mg2+ deprivation on the distribution and function of claudin-16 using Madin-Darby canine kidney (MDCK) cells expressing FLAG-tagged claudin-16. Mg2+ deprivation inhibited the localization of claudin-16 at tight junctions, but did not affect the localization of other claudins. Re-addition of Mg2+ induced the tight junctional localization of claudin-16, which was inhibited by U0126, a MEK inhibitor. Transepithelial permeability to Mg2+ was also inhibited by U0126. The phosphorylation of ERK was reduced by Mg2+ deprivation, and recovered by re-addition of Mg2+. These results suggest that the MEK/ERK-dependent phosphorylation of claudin-16 affects the tight junctional localization and function of claudin-16. Mg2+ deprivation decreased the phosphothreonine levels of claudin-16. The phosphothreonine levels of T225A and T233A claudin-16 were decreased in the presence of Mg2+ and these mutants were widely distributed in the plasma membrane. Furthermore, TER and transepithelial Mg2+ permeability were decreased in the mutants. We suggest that the tight junctional localization of claudin-16 requires a physiological Mg2+ concentration and the phosphorylation of threonine residues via a MEK/ERK-dependent pathway. 相似文献
147.
Akira Ikari Kosuke Atomi Keishi Kinjo Yohei Sasaki Junko Sugatani 《Life sciences》2010,86(19-20):766-773
AimsLoss of magnesium (Mg2+) inhibits cell proliferation and augments nephrotoxicant-induced renal injury, but the role of Mg2+ has not been clarified in detail. We examined the effect of extracellular Mg2+ deprivation on a MEK–ERK cascade and cell proliferation using a renal epithelial cell line, Madin-Darby canine kidney (MDCK) cells.Main methodsMDCK cells were cultured in Mg2+-containing or Mg2+-free media. A HA-tagged constitutively active (CA)-MEK1 and a dominant negative (DN)-MEK1 were transfected into MDCK cells. The level of protein was examined by Western blotting. The intracellular free Mg2+ concentration ([Mg2+]i) was measured using a fluorescent dye, mag-fura 2. Cell proliferation was determined by WST-1 assay. Dead cells were identified by staining with annexin V-FITC and propidium iodide.Key findingsIn the presence of fetal calf serum (FCS), Mg2+ deprivation decreased phosphorylated-ERK1/2 (p-ERK1/2) levels and [Mg2+]i. Re-addition of Mg2+ increased p-ERK1/2 levels, which were inhibited by U0126, a specific inhibitor of a MEK–ERK cascade. Glutathione-S-transferase pull-down and coimmunoprecipitation assays showed that CA-MEK1 and DN-MEK1 binds with ERK1/2 in the presence of Mg2+. In contrast, neither CA-MEK1 nor DN-MEK1 bound to ERK1/2 in the absence of Mg2+. These results indicate that the MEK–ERK cascade is regulated by [Mg2+]i. Cell proliferation was increased by the treatment with FCS or the expression of CA-MEK1 in the presence of Mg2+, but was inhibited by Mg2+ deprivation. Mg2+ deprivation did not increase the number of dead cells.SignificanceMg2+ is involved in the regulation of the MEK–ERK cascade and cell proliferation in MDCK cells. 相似文献
148.
Ode H Matsuyama S Hata M Neya S Kakizawa J Sugiura W Hoshino T 《Journal of molecular biology》2007,370(3):598-607
A prominent characteristic of human immunodeficiency virus type 1 (HIV-1) is its high genetic variability, which generates diversity of the virus and often causes a serious problem of the emergence of drug-resistant mutants. Subtype B HIV-1 is dominant in advanced countries, and the mortality rate due to subtype B HIV-1 has been decreased during the past decade. In contrast, the number of patients with non-subtype B viruses is still increasing in developing countries. One of the reasons for the prevalence of non-subtype B viruses is lack of information about the biological and therapeutic differences between subtype B and non-subtype B viruses. M36I is the most frequently observed polymorphism in non-subtype B HIV-1 proteases. However, since the 36th residue is located at a non-active site of the protease and has no direct interaction with any ligands, the structural role of M36I remains unclear. Here, we performed molecular dynamics (MD) simulations of M36I protease in complex with nelfinavir and revealed the influence of the M36I mutation. The results show that M36I regulates the size of the binding cavity of the protease. The reason for the rare emergence of D30N variants in non-subtype B HIV-1 proteases was also clarified from our computational analysis. 相似文献
149.
Rowbottom MW Vickers TD Tamiya J Zhang M Dyck B Grey J Schwarz D Heise CE Hedrick M Wen J Tang H Wang H Fisher A Aparicio A Saunders J Goodfellow VS 《Bioorganic & medicinal chemistry letters》2007,17(8):2171-2178
The design, synthesis, and SAR of a series of substituted spirohydantoins are described. Optimization of an in-house screening hit gave compounds that exhibited potent binding affinity and functional activity at MCH-R1. 相似文献
150.
To realize highly integrated micro total analysis systems (microTAS), a simply controlled miniaturized valve should be utilized on microfluidic device. In this paper, we describe the application of photo-induced super-hydrophilicity of titanium dioxide (TiO2) to microfluidic manipulation. In addition, we found a new phenomenon for reversibly converting the surface wettability using a polydimethylsiloxane (PDMS) matrix and the photocatalytic properties of TiO2. While PDMS polymer was irradiated with UV, it was confirmed that hydrophobic material was released from the polymer to air. Several prepolymers were identified as the hydrophobic material with a gas chromatograph and mass spectrometer (GC/MS). Here, we successfully demonstrated the flexible manipulation of microfluid in a branched microchannel using the reversible wettability as micro opto-switching valve (MOS/V). The simultaneous control of MOS/Vs was also demonstrated on a 256-MOS/V integrated disk. The MOS/V promises to be one of the most effective flow switching valves for advanced applications in highly integrated micro/nano fluidics. 相似文献