全文获取类型
收费全文 | 4233篇 |
免费 | 237篇 |
出版年
2021年 | 44篇 |
2020年 | 35篇 |
2019年 | 40篇 |
2018年 | 68篇 |
2017年 | 50篇 |
2016年 | 59篇 |
2015年 | 131篇 |
2014年 | 147篇 |
2013年 | 243篇 |
2012年 | 225篇 |
2011年 | 243篇 |
2010年 | 146篇 |
2009年 | 177篇 |
2008年 | 266篇 |
2007年 | 253篇 |
2006年 | 243篇 |
2005年 | 200篇 |
2004年 | 220篇 |
2003年 | 218篇 |
2002年 | 240篇 |
2001年 | 84篇 |
2000年 | 115篇 |
1999年 | 74篇 |
1998年 | 37篇 |
1997年 | 35篇 |
1996年 | 39篇 |
1995年 | 42篇 |
1994年 | 30篇 |
1993年 | 39篇 |
1992年 | 69篇 |
1991年 | 61篇 |
1990年 | 52篇 |
1989年 | 75篇 |
1988年 | 70篇 |
1987年 | 49篇 |
1986年 | 36篇 |
1985年 | 30篇 |
1984年 | 23篇 |
1983年 | 18篇 |
1982年 | 29篇 |
1981年 | 20篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 16篇 |
1977年 | 15篇 |
1976年 | 21篇 |
1975年 | 13篇 |
1974年 | 11篇 |
1973年 | 14篇 |
1969年 | 19篇 |
排序方式: 共有4470条查询结果,搜索用时 15 毫秒
1.
Subrina Jesmin Nobutake Shimojo Naoto Yamaguchi Chishimba Nathan Mowa Masami Oki Sohel Zaedi Sayeeda Nusrat Sultana Arifur Rahman Majedul Islam Atsushi Sawamura Satoshi Gando Satoru Kawano Takashi Miyauchi Taro Mizutani 《Life sciences》2014
Aims
Septic shock, the severe form of sepsis, is associated with development of progressive damage in multiple organs. Kidney can be injured and its functions altered by activation of coagulation, vasoactive-peptide and inflammatory processes in sepsis. Endothelin (ET)-1, a potent vasoconstrictor, is implicated in the pathogenesis of sepsis and its complications. Protease-activated receptors (PARs) are shown to play an important role in the interplay between inflammation and coagulation. We examined the time-dependent alterations of ET-1 and inflammatory cytokine, such as tumor necrosis factor (TNF)-α in kidney tissue in lipopolysaccharide (LPS)-induced septic rat model and the effects of PAR2 blocking peptide on the LPS-induced elevations of renal ET-1 and TNF-α levels.Main methods
Male Wistar rats at 8 weeks of age were administered with either saline solution or LPS at different time points (1, 3, 6 and 10 h). Additionally, we treated LPS-administered rats with PAR2 blocking peptide for 3 h to assess whether blockade of PAR2 has a regulatory role on the ET-1 level in septic kidney.Key findings
An increase in ET-1 peptide level was observed in kidney tissue after LPS administration time-dependently. Levels of renal TNF-α peaked (around 12-fold) at 1 h of sepsis. Interestingly, PAR2 blocking peptide normalized the LPS-induced elevations of renal ET-1 and TNF-α levels.Significance
The present study reveals a distinct chronological expression of ET-1 and TNF-α in LPS-administered renal tissues and that blockade of PAR2 may play a crucial role in treating renal injury, via normalization of inflammation, coagulation and vaso-active peptide. 相似文献2.
Upregulation of integrins alpha v beta 3 and alpha v beta 5 on human monocytes and T lymphocytes facilitates adenovirus-mediated gene delivery. 总被引:16,自引:10,他引:6 下载免费PDF全文
Entry of human adenovirus into host cells involves interaction of virus particles with two distinct receptors. The initial binding event is mediated by the fiber protein, while subsequent interaction of the penton base protein with alpha v integrins promotes virus internalization and/or penetration. Although these interactions in epithelial and endothelial cells have been well characterized, relatively little is known as to whether these events occur during virus infection of human peripheral blood mononuclear cells. We demonstrate that freshly isolated peripheral blood monocytes and T lymphocytes express very small amounts of alpha v integrins and also are resistant to adenovirus infection. Exposure of monocytes to hematopoietic growth factors granulocyte-macrophage colony-stimulating factor and macrophage colony-stimulating factor induced expression of cell surface alpha v integrins, promoted the binding of penton base protein, and also rendered these cells susceptible to adenovirus-mediated gene delivery. Stimulation of T cells with a mitogen, phytohemagglutinin, or a cell-activating agent, phorbol myristate acetate, induced expression of alpha v integrins and also enhanced adenovirus-mediated gene delivery. These studies further indicate that alpha v integrins play a crucial role in adenovirus infection and also provide a useful strategy for enhancing adenovirus-mediated gene delivery into human peripheral blood mononuclear cells. 相似文献
3.
Yuki Suzuki Masayuki Endo Cristina Ca?as Silvia Ayora Juan C. Alonso Hiroshi Sugiyama Kunio Takeyasu 《Nucleic acids research》2014,42(11):7421-7428
Holliday junction (HJ) resolution is a fundamental step for completion of homologous recombination. HJ resolving enzymes (resolvases) distort the junction structure upon binding and prior cleavage, raising the possibility that the reactivity of the enzyme can be affected by a particular geometry and topology at the junction. Here, we employed a DNA origami nano-scaffold in which each arm of a HJ was tethered through the base-pair hybridization, allowing us to make the junction core either flexible or inflexible by adjusting the length of the DNA arms. Both flexible and inflexible junctions bound to Bacillus subtilis RecU HJ resolvase, while only the flexible junction was efficiently resolved into two duplexes by this enzyme. This result indicates the importance of the structural malleability of the junction core for the reaction to proceed. Moreover, cleavage preferences of RecU-mediated reaction were addressed by analyzing morphology of the reaction products. 相似文献
4.
Ryu Sasaki Kazumi Yamasaki Seigo Abiru Atsumasa Komori Shinya Nagaoka Akira Saeki Satoru Hashimoto Shigemune Bekki Yuki Kugiyama Atsushi Kuno Masaaki Korenaga Akira Togayachi Makoto Ocho Masashi Mizokami Hisashi Narimatsu Tatsuki Ichikawa Kazuhiko Nakao Hiroshi Yatsuhashi 《PloS one》2015,10(6)
Measurement of Wisteria floribunda agglutinin-positive human Mac-2 binding protein (WFA+-M2BP) in serum was recently shown to be a noninvasive method to assess liver fibrosis. The aim of this study was to evaluate the utility of serum WFA+-M2BP values to predict the development of hepatocellular carcinoma (HCC) in patients who achieved a sustained virological response (SVR) by interferon treatment. For this purpose, we retrospectively analyzed 238 patients with SVR who were treated with interferon in our department. Serum WFA+-M2BP values were measured at pre-treatment (pre-Tx), post-treatment (24 weeks after completion of interferon; post-Tx), the time of HCC diagnosis, and the last clinical visit. Of 238 patients with SVR, HCC developed in 16 (6.8%) patients. The average follow-up period was 9.1 years. The cumulative incidence of HCC was 3.4% at 5 years and 7.5% at 10 years. The median pre-Tx and post-Tx WFA+-M2BP values were 1.69 (range: 0.28 to 12.04 cutoff index (COI)) and 0.80 (range: 0.17 to 5.29 COI), respectively. The WFA+-M2BP values decreased significantly after SVR (P < 0.001). The median post-Tx WFA+-M2BP value in patients who developed HCC was significantly higher than that in patients who did not (P < 0.01). Multivariate analysis disclosed that age (> 60 years), sex (male), pre-Tx platelet count (< 15.0×103/μL), and post-Tx WFA+-M2BP (> 2.0 COI) were associated with the development of HCC after SVR.
Conclusion
Post-Tx WFA+-M2BP (> 2.0 COI) is associated with the risk for development of HCC among patients with SVR. The WFA+-M2BP values could be a new predictor for HCC after SVR. 相似文献5.
Ryosuke Tateishi Nobuko Akiyama Maki Miyauchi Riko Yoshinaga Hiroki Sasanuma Takashi Kudo Miki Shimbo Masahiro Shinohara Koji Obata Jun-ichiro Inoue Masaki Shirakawa Dai Shiba Hiroshi Asahara Nobuaki Yoshida Satoru Takahashi Hironobu Morita Taishin Akiyama 《PloS one》2015,10(10)
Gravity change affects many immunological systems. We investigated the effects of hypergravity (2G) on murine thymic cells. Exposure of mice to 2G for three days reduced the frequency of CD4+CD8+ thymocytes (DP) and mature medullary thymic epithelial cells (mTECs), accompanied by an increment of keratin-5 and keratin-8 double-positive (K5+K8+) TECs that reportedly contain TEC progenitors. Whereas the reduction of DP was recovered by a 14-day exposure to 2G, the reduction of mature mTECs and the increment of K5+K8+ TEC persisted. Interestingly, a surgical lesion of the inner ear’s vestibular apparatus inhibited these hypergravity effects. Quantitative PCR analysis revealed that the gene expression of Aire and RANK that are critical for mTEC function and development were up-regulated by the 3-day exposure and subsequently down-regulated by the 14-day exposure to 2G. Unexpectedly, this dynamic change in mTEC gene expression was independent of the vestibular apparatus. Overall, data suggest that 2G causes a temporary reduction of DP and a persistent reduction of mature mTECs in a vestibular system-dependent manner, and also dysregulates mTEC gene expression without involving the vestibular system. These data might provide insight on the impact of gravity change on thymic functions during spaceflight and living. 相似文献
6.
Hideki Yoshida Toshihiko Imamura Akiko M. Saito Yoshihiro Takahashi So-ichi Suenobu Daiichiro Hasegawa Takao Deguchi Yoshiko Hashii Hirohide Kawasaki Mikiya Endo Hiroki Hori Nobuhiro Suzuki Yoshiyuki Kosaka Koji Kato Keiko Yumura-Yagi Junichi Hara Megumi Oda Atsushi Sato Keizo Horibe Japan Association of Childhood Leukemia Study 《PloS one》2015,10(8)
Although L-asparaginase related hyperglycemia is well known adverse event, it is not studied whether the profile of this adverse event is affected by intensification of L-asparaginase administration. Here, we analyzed the profile of L-asparaginase related hyperglycemia in a 1,176 patients with pediatric acute lymphoblastic leukemia treated according to the Japan Association of Childhood Leukemia Study ALL-02 protocol using protracted L-asparaginase administration in maintenance phase. We determined that a total of 75 L-asparaginase related hyperglycemia events occurred in 69 patients. Although 17 events (17/1176, 1.4%) developed in induction phase, which was lower incidence than those (10–15%) in previous reports, 45 events developed during the maintenance phase with protracted L-asparaginase administration. Multivariate analysis showed that older age at onset (≥10 years) was a sole independent risk factor for L-asparaginase-related hyperglycemia (P<0.01), especially in maintenance phase. Contrary to the previous reports, obesity was not associated with L-asparaginase-related hyperglycemia. These findings suggest that protracted administration of L-asparaginase is the risk factor for hyperglycemia when treating adolescent and young adult acute lymphoblastic leukemia patients. 相似文献
7.
Kaori Matsumoto Yuji Nakai Masaru Hoshino Koki Yamazaki Yoshiaki Takioto Satoru Takadera 《Bioscience, biotechnology, and biochemistry》2017,81(10):1926-1936
Tenascin-C (TNC), an extracellular matrix glycoprotein, plays a pivotal role in tumor growth. However, the mechanism whereby TNC affects tumor biology remains unclear. To investigate the exact role of TNC in primary tumor growth, a mouse mammary tumor cell line, GLMT1, was first developed. Subsequently, global gene expression in GLMT1-derived tumors was compared between wild-type (WT) and TNC-knockout (TNKO) mice. Tumors in WT mice were significantly larger than those in TNKO mice. DNA microarray analysis revealed 447 up and 667 downregulated in the tumors inoculated into TNKO mice as compared to tumors in WT mice. Validation by quantitative gene expression analysis showed that Tnc, Cxcl1, Cxcl2, and Cxcr2 were significantly upregulated in WT mice. We hypothesize that TNC stimulates the CXCL1/2-CXCR2 pathway involved in cancer cell proliferation. 相似文献
8.
Michael D. Browning Shuichi Endo Geoffrey B. Smith Ellen M. Dudek Richard W. Olsen 《Neurochemical research》1993,18(1):95-100
Previous work has shown that the GABAA-receptor (GABAA-R) could be phosphorylated by cAMP-dependent protein kinase (PKA), protein kinase C (PKC), and a receptor associated kinase. However, no clear picture has yet emerged concerning the particular subunit subtypes of the GABAA-R that were phosphorylated by PKA and PKC. In the present report we show that an antibody raised against a 23 amino acid polypeptide corresponding to a sequence in the putative intracellular loop of the 1 subunit of the receptor blocks the in vitro phosphorylation of the purified receptor by PKA and PKC. Moreover, N-terminal sequence analysis of the principal phosphopeptide fragment obtained after proteolysis of the receptor yielded a sequence that corresponds to the 3 subunit of the receptor. Such data provide additional support for our hypothesis (Browning et al., 1990, Proc. Natl. Acad. Sci. USA 87:1315–1317) that both PKA and PKC phosphorylate the -subunit of the GABAA-R.Special issue dedicated to Dr. Paul Greengard. 相似文献
9.
Yasuhiro Katou Naoya Endo Toshiyuki Suzuki Jiang Yu Haruhisa Kikuchi Yoshiteru Oshima Yoshimi Homma 《Life sciences》2014
Aims
Metarhizin A was originally isolated from Metarhizium flavoviride as a potent inhibitor of the growth of insect and mammalian cells. In this study, we aimed to understand the molecular targets of metarhizin A involved in its anti-proliferative activity against human cells.Main methods
Cell cycle regulators and signaling molecules were examined by immunoblotting using specific antibodies. A mitochondria-enriched fraction was prepared from mouse liver, and mitochondrial activity was monitored using an oxygen electrode. Enzyme activity was measured using purified cytochrome c oxidase and permeabilized cells.Key findings
Metarhizin A inhibits the growth of MCF-7 cells with an IC50 value of ~ 0.2 μM and other cells in a similar manner; a cell cycle-dependent kinase inhibitor, p21, is selectively induced. Significant amounts of reactive oxygen species (ROS) are generated and ERK1/2 is activated in cells treated with metarhizin A. Metarhizin A completely suppresses oxygen consumption by mitochondria, and potently inhibits the activity of cytochrome c oxidase. It induces cell death when MCF-7 cells are cultured under limiting conditions.Significance
Metarhizin A is a potent inhibitor of cytochrome c oxidase and activates the MAPK pathway through the generation of ROS, which induces growth arrest of cells, and, under some conditions, enhances cell death. The cytochrome c oxidase system is a possible molecular target of metarhizin A. 相似文献10.
Species‐dependent microarchitectural traits of iridescent scales in the triad taxa of Ornithoptera birdwing butterflies 下载免费PDF全文
Makoto Kazama Mai Ichinei Saori Endo Masaki Iwata Akiya Hino Joji M. Otaki 《Entomological Science》2017,20(1):255-269
Ornithoptera birdwing butterflies have blue, green, or orange iridescent scales in different species or subspecies. To understand the species‐ or subspecies‐dependent scale color differences, we performed comparative morphometric analyses of iridescent scales from three closely related taxa: O. priamus priamus (green), O. priamus urvillianus (blue), and O. croesus (orange). The three types of Ornithoptera wings exhibited reversible color changes to longer wavelengths with different kinetics upon immersion in methanol, suggesting that their color differences are at least partly based on differences in the size of air cavities made by nanostructures. Cover scales of all three color types were visually semi‐transparent glass scales that exhibited color when placed on a dark background. The dorsoventral differences in coloration were observed in single scales, suggesting the optical importance of scale surfaces. Scanning electron microscopy of cover scales in cross section revealed that all color types exhibited finely sculpted tapered ridges and thick, irregular basal multilayers containing tandemly clustered granular objects and air cavities. Scale thickness, ridge height, and multilayer thickness were significantly different among the three color types, and granular object size was significantly different between orange scales and blue and green scales. We conclude that each of the three taxa of Ornithoptera butterflies possesses unique quantitative size values on tapered ridges and irregular multilayers with granular objects and air cavities to express unique structural color. These species‐ or subspecies‐dependent structural colors might have evolved via quantitative shifts in these microarchitectural traits rather than via changes in the basic developmental or architectural plan for color expression. 相似文献