全文获取类型
收费全文 | 985篇 |
免费 | 42篇 |
专业分类
1027篇 |
出版年
2024年 | 4篇 |
2023年 | 5篇 |
2022年 | 13篇 |
2021年 | 34篇 |
2020年 | 14篇 |
2019年 | 27篇 |
2018年 | 27篇 |
2017年 | 30篇 |
2016年 | 41篇 |
2015年 | 43篇 |
2014年 | 60篇 |
2013年 | 67篇 |
2012年 | 99篇 |
2011年 | 85篇 |
2010年 | 47篇 |
2009年 | 38篇 |
2008年 | 48篇 |
2007年 | 64篇 |
2006年 | 51篇 |
2005年 | 32篇 |
2004年 | 37篇 |
2003年 | 35篇 |
2002年 | 33篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有1027条查询结果,搜索用时 0 毫秒
11.
Expression of cytokeratin 20 in urine cytology smears: a potential marker for the detection of urothelial carcinoma 总被引:1,自引:0,他引:1
A. Bhatia P. Dey Y. Kumar U. Gautam N. Kakkar R. Srinivasan R. Nijhawan 《Cytopathology》2007,18(2):84-86
BACKGROUND: Urine cytomorphology is one of the oldest methods for screening and monitoring patients with transitional cell carcinoma (TCC). Sensitivity of urine cytology is relatively low. Ancillary techniques on urine sample may increase the sensitivity. AIM: To explore the utility of cytokeratin 20 (CK20) immunostaining in identifying malignant cells in urine cytology smears. MATERIALS AND METHODS: Fourteen cases each of confirmed TCC and benign urinary cytology along with five cases of atypical cells in urine were immunostained with a monoclonal CK20 antibody. Of 14 cases of TCC, 12 showed strong positive staining with the antibody. All benign cases were negative except for a few cases in which the umbrella cells were weakly to moderately positive. In all five cases of atypical urine cytology the atypical cells stained positive with the antibody. These cases were later confirmed as TCC on histopathology of bladder wall biopsy. CONCLUSION: CK20 is an important biomarker that can be used to identify TCC in urine cytology smears. It is particularly useful in those cases where malignancy cannot be confirmed by morphology alone. 相似文献
12.
17-epiestriol,an estrogen metabolite,is more potent than estradiol in inhibiting vascular cell adhesion molecule 1 (VCAM-1) mRNA expression 总被引:1,自引:0,他引:1
Mukherjee TK Nathan L Dinh H Reddy ST Chaudhuri G 《The Journal of biological chemistry》2003,278(14):11746-11752
17-beta estradiol (17-beta E(2)) attenuates the expression of vascular cell adhesion molecule 1 (VCAM-1) in vivo at physiological levels (pg/ml), whereas supraphysiological concentrations of 17-beta E(2) (ng/ml) are required in vitro. We assessed whether a metabolite of estrogen, which could only be generated in vivo, might be a more potent inhibitor of VCAM-1 expression and thereby explain this discrepancy. We report here that 17-epiestriol, an estrogen metabolite and a selective estrogen receptor (ER) beta agonist, is approximately 400x more potent than 17-beta E(2) in suppressing tumor necrosis factor (TNF) alpha-induced VCAM-1 mRNA as well as protein expression in human umbilical vein endothelial cells. Genistein, an ERbeta agonist, at low concentrations (1 and 10 nm) also suppressed TNFalpha-induced VCAM-1 mRNA expression. These actions of 17-epiestriol and genistein were significantly attenuated in the presence of the estrogen receptor antagonist ICI-182780. Other estrogenic compounds such as ethinyl estradiol and estrone did not have any effect on TNFalpha-induced VCAM-1 expression at the concentrations tested. We further show that, 1) 17-epiestriol induces the expression of endothelial nitric-oxide synthase mRNA and protein, 2) 17-epiestriol prevents TNFalpha-induced migration of NFkappaB into the nucleus, 3) N(G)-nitro-l-arginine methyl ester, an inhibitor of NO synthesis, abolishes 17-epiestriol-mediated inhibition of TNFalpha-induced VCAM-1 expression and migration of NFkappaB from the cytoplasm to the nucleus. Our results indicate that 17-epiestriol is more potent than 17-beta E(2) in suppressing TNFalpha-induced VCAM-1 expression and that this action is modulated at least in part through NO. 相似文献
13.
14.
Verma V Gautam SK Singh B Manik RS Palta P Singla SK Goswami SL Chauhan MS 《Molecular reproduction and development》2007,74(4):520-529
This study was carried out to isolate and characterize buffalo embryonic stem (ES) cell-like cells from in vitro-produced embryos. Inner cell mass (ICM) cells were isolated either mechanically or by enzymatic digestion from 120 blastocysts whereas 28 morulae were used for the isolation of blastomeres mechanically. The ICM cells/ blastomeres were cultured on mitomycin-C-treated feeder layer. Primary cell colony formation was higher (P < 0.05) for hatched blastocysts (73.1%, 30/41) than that for early/expanded blastocysts (25.3%, 20/79). However, no primary cell colonies were formed when blastomeres obtained from morulae were cultured. Primary colonies were formed in 14.1% (12/85) of intact blastocyst culture, which was significantly lower (P < 0.05) than that of 41.6% for ICM culture. These colonies were separated by enzymatic or mechanical disaggregation. Using mechanical disaggregation method, the cells remained undifferentiated and two buffalo ES cell-like cell lines (bES1, bES2) continued to grow in culture up to eight passages. However, disassociation through enzymatic method resulted in differentiation. Undifferentiated cells exhibited stem cell morphological features, normal chromosomal morphology, and expressed specific markers such as alkaline phosphatase (AP) and Oct-4. Cells formed embryoid bodies (EBs) in suspension culture; extended culture of EBs resulted in formation of cystic EBs. Following prolonged in vitro culture, these cells differentiated into several types of cells including neuron-like and epithelium-like cells. Furthermore, the vitrified-thawed ES cell-like cells also exhibited typical stem cell characteristics. In conclusion, buffalo ES cell-like cells could be isolated from in vitro-produced blastocysts and maintained in vitro for prolonged periods of time. 相似文献
15.
Yang R Sikka G Larson J Watts VL Niu X Ellis CL Miller KL Camara A Reinke C Savransky V Polotsky VY O'Donnell CP Berkowitz DE Barouch LA 《American journal of physiology. Heart and circulatory physiology》2011,300(4):H1467-H1476
Chronic intermittent hypoxia (IH) during sleep can result from obstructive sleep apnea (OSA), a disorder that is particularly prevalent in obesity. OSA is associated with high levels of circulating leptin, cardiovascular dysfunction, and dyslipidemia. Relationships between leptin and cardiovascular function in OSA and chronic IH are poorly understood. We exposed lean wild-type (WT) and obese leptin-deficient ob/ob mice to IH for 4 wk, with and without leptin infusion, and measured cardiovascular indices including aortic vascular stiffness, endothelial function, cardiac myocyte morphology, and contractile properties. At baseline, ob/ob mice had decreased vascular compliance and endothelial function vs. WT mice. We found that 4 wk of IH decreased vascular compliance and endothelial relaxation responses to acetylcholine in both WT and leptin-deficient ob/ob animals. Recombinant leptin infusion in both strains restored IH-induced vascular abnormalities toward normoxic WT levels. Cardiac myocyte morphology and function were unaltered by IH. Serum cholesterol and triglyceride levels were significantly decreased by leptin treatment in IH mice, as was hepatic stearoyl-Coenzyme A desaturase 1 expression. Taken together, these data suggest that restoring normal leptin signaling can reduce vascular stiffness, increase endothelial relaxation, and correct dyslipidemia associated with IH. 相似文献
16.
Anne Marie S. Harding Nobuyoshi Kusama Tomonori Hattori Mamta Gautam Christopher J. Benson 《PloS one》2014,9(4)
Acid-sensing ion channels (ASICs) are Na+ channels activated by changes in pH within the peripheral and central nervous systems. Several different isoforms of ASICs combine to form trimeric channels, and their properties are determined by their subunit composition. ASIC2 subunits are widely expressed throughout the brain, where they heteromultimerize with their partnering subunit, ASIC1a. However, ASIC2 contributes little to the pH sensitivity of the channels, and so its function is not well understood. We found that ASIC2 increased cell surface levels of the channel when it is coexpressed with ASIC1a, and genetic deletion of ASIC2 reduced acid-evoked current amplitude in mouse hippocampal neurons. Additionally, ASIC2a interacted with the neuronal synaptic scaffolding protein PSD-95, and PSD-95 reduced cell surface expression and current amplitude in ASICs that contain ASIC2a. Overexpression of PSD-95 also reduced acid-evoked current amplitude in hippocampal neurons. This result was dependent upon ASIC2 since the effect of PSD-95 was abolished in ASIC2−/− neurons. These results lend support to an emerging role of ASIC2 in the targeting of ASICs to surface membranes, and allows for interaction with PSD-95 to regulate these processes. 相似文献
17.
Trichomonas vaginalis causes the trichomoniasis, in women and urethritis and prostate cancer in men. Its genome draft published by TIGR in 2007 presents many unusual genomic and biochemical features like, exceptionally large genome size, the presence of hydrogenosome, gene duplication, lateral gene transfer mechanism and the presence of miRNA. To understand some of genomic features we have performed a comparative analysis of metabolic pathways of the T. vaginalis with other 22 significant common organisms. Enzymes from the biochemical pathways of T. vaginalis and other selected organisms were retrieved from the KEGG metabolic pathway database. The metabolic pathways of T. vaginalis common in other selected organisms were identified. Total 101 enzymes present in different metabolic pathways of T. vaginalis were found to be orthologous by using BLASTP program against the selected organisms. Except two enzymes all identified orthologous enzymes were also identified as paralogous enzymes. Seventy-five of identified enzymes were also identified as essential for the survival of T. vaginalis, while 26 as non-essential. The identified essential enzymes also represent as good candidate for novel drug targets. Interestingly, some of the identified orthologous and paralogous enzymes were found playing significant role in the key metabolic activities while others were found playing active role in the process of pathogenesis. The N-acetylneuraminate lyase was analyzed as the candidate of lateral genes transfer. These findings clearly suggest the active participation of lateral gene transfer and gene duplication during evolution of T. vaginalis from the enteric to the pathogenic urogenital environment. 相似文献
18.
Mishra JK Garg P Dohare P Kumar A Siddiqi MI Ray M Panda G 《Bioorganic & medicinal chemistry letters》2007,17(5):1326-1331
A series of 3-substituted 1,4-benzodiazepin-2-ones derived from S and R amino acids were evaluated for their anti-ischemic activity in vitro. Treatment with compounds 7h, 16, 9d, and 17 decreased the apoptotic neuronal number, however increased the neuronal viability. The compounds decreasing apoptosis could protect neurons from the ischemic injury. The difference in the activities of 1,4-benzodiazepin-2-ones derived from S- and R-amino acids is discussed and explained on the basis of molecular modeling studies. 相似文献
19.
Singhal P Gaur A Behl V Gautam A Varshney B Paliwal J Batra V 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,852(1-2):293-299
A simple, sensitive and rapid liquid chromatography/tandem mass spectrometric (LC-MS/MS) method was developed and validated for quantification of chloroquine, an antimalarial drug, in plasma using its structural analogue, piperazine bis chloroquinoline as internal standard (IS). The method is based on simple protein precipitation with methanol followed by a rapid isocratic elution with 10 mM ammonium acetate buffer/methanol (25/75, v/v, pH 4.6) on Chromolith SpeedROD RP-18e reversed phase chromatographic column and subsequent analysis by mass spectrometry in the multiple reaction monitoring mode (MRM). The precursor to product ion transitions of m/z 320.3-->247.2 and m/z 409.1-->205.2 were used to measure the analyte and the IS, respectively. The assay exhibited a linear dynamic range of 2.0-489.1 ng/mL for chloroquine in dog plasma. The limit of detection (LOD) and lower limit of quantification (LLOQ) were 0.4 and 2.0 ng/mL, respectively in 0.05 mL plasma. Acceptable precision and accuracy were obtained for concentrations over the standard curve range of 2.0-489.1 ng/mL. A run time of 2.0 min for a sample made it possible to achieve a throughput of more than 400 plasma samples analyzed per day. The validated method was successfully used to analyze samples of dog plasma during non-clinical study of chloroquine. 相似文献
20.