全文获取类型
收费全文 | 468篇 |
免费 | 28篇 |
国内免费 | 3篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 12篇 |
2020年 | 11篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 4篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 25篇 |
2013年 | 39篇 |
2012年 | 23篇 |
2011年 | 42篇 |
2010年 | 19篇 |
2009年 | 7篇 |
2008年 | 27篇 |
2007年 | 19篇 |
2006年 | 18篇 |
2005年 | 25篇 |
2004年 | 18篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 12篇 |
1998年 | 4篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1973年 | 2篇 |
1971年 | 4篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1964年 | 2篇 |
排序方式: 共有499条查询结果,搜索用时 15 毫秒
1.
Cassidy S. S.; Wead W. B.; Seibert G. B.; Ramanathan M. 《Journal of applied physiology》1987,63(2):803-811
The purpose of these experiments was to determine the effects of a spontaneously generated inspiration on the size and shape of the left ventricle (LV) in anesthetized supine dogs. We implanted markers in the LV to establish three perpendicular axes and recorded the motion of these markers using biplane cinefluoroscopy at 60 Hz. The primary changes in LV size that accompanied inspiration occurred at end diastole (ED). The largest change in LVED dimension was a 2.46-mm narrowing of the septal-lateral wall dimension, but the apex-base dimension decreased also, by 0.74 mm. The anteroposterior dimension actually widened by 1.07 mm. The septal-lateral narrowing was caused by both a 1.0-mm narrowing of the distance between the septal marker and the apex-base axis, as well as by a 1.4-mm narrowing between the apex-base axis and the lateral wall marker. Narrowing of the septal portion seemed expected because of presumed enhanced right ventricular filling during inspiration. Narrowing of the lateral portion of the LV, while the anteroposterior dimension widened, was surprising because a change in LVEDV shape is implied. Assuming ventricular homogeneity, this change in LVED shape implies that the forces applied to the epicardial surface were not uniform. There must have been a retraction on the anterior and posterior surface that was not experienced by the lateral LV wall. The net effect of these dimensional changes of the LV at end diastole (estimated from the product of the three ED axes) was a 3.5-cm3 reduction in LVED volume.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
2.
K. Usha Deniz P. S. Parvathanathan Geeta Datta C. L. Khetrapal K. V. Ramanathan N. Suryaprakash S. Raghotama 《Journal of biosciences》1990,15(3):117-123
The influence of the sulfone drugs, diamino diphenyl sulfone and diamino monophenyl sulfone on the phase transitions and dynamics
of dipalmitoyl phosphatidyl choline-H2O/D2O vesicles have been investigated using differential scanning calorimetry and nuclear magnetic resonance. Our results show
that diamino diphenyl sulfone interacts quite strongly with the headgroups of dipalmitoyl phosphatidyl choline whereas the
diamino monophenyl sulfone-dipalmitoyl phosphatidyl choline interaction is quite weak. This is attributed to the difference
in the structure and hydrophobic character of the two drugs. 相似文献
3.
4.
5.
6.
The swimming behavior of Paramecium is regulated by an excitable membrane that covers the body and cilia of the protozoan. In order to obtain information on the topology and function of ciliary membrane proteins, Paramecia were treated with trypsin, chymotrypsin or pronase and the effects of these proteases were analyzed using electron microscopy, gel electrophoresis of ciliary fractions and behavioral tests. At the concentrations used, trypsin and chymotrypsin had little or no effect on the cells while pronase removed the cell surface coat, visible as fuzzy material covering the cell membrane. The same pronase treatment caused the specific removal of a high molecular weight protein (250 000), as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis. This protein, the ‘immobilization antigen’, constitutes the major protein of the ciliary membrane. Although the immobilization antigen was removed (or markedly decreased), no marked and reproducible difference was observed in the swimming behavior of the treated cells. We also determined the effects of proteases on isolated ciliary fractions to explore the sidedness of ciliary membrane proteins. A set of proteins relatively resistant to protease digestion was identified; they may be intrinsic membrane proteins. 相似文献
7.
Hematophagous activity of Mecistocirrus digitatus, which causes substantial blood and weight loss in large ruminants, is an emerging challenge due to the economic loss it brings to the livestock industry. Infected animals are treated with anthelmintic drugs, based on the identification of helminth species and the severity of infection; however, traditional methods such as microscopic identification and the counting of eggs for diagnosis and determination of level of infection are laborious, cumbersome and unreliable. To facilitate the detection of this parasite, a SYBR green-based real-time PCR was standardized and validated for the detection of M. digitatus infection in cattle and buffaloes. Oligonucleotides were designed to amplify partial Internal Transcribed Spacer (ITS)-1 sequence of M. digitatus. The specificity of the primers was confirmed by non-amplification of DNA extracted from other commonly occurring gastrointestinal nematodes in ruminants. Plasmids were ligated with partial ITS-1 sequence of M. digitatus, serially diluted (hundred fold) and used as standards in the real-time PCR assay. The quantification cycle (Cq) values were plotted against the standard DNA concentration to produce a standard curve. The assay was sensitive enough to detect one plasmid containing the M. digitatus DNA. Clinical application of this assay was validated by testing the DNA extracted from the faeces of naturally infected cattle (n = 40) and buffaloes (n = 25). The results were compared with our standard curve to calculate the quantity of M. digitatus in each faecal sample. The Cq value of the assay depicted a strong linear relationship with faecal DNA content, with a regression coefficient of 0.984 and efficiency of 99%. This assay has noteworthy advantages over the conventional methods of diagnosis because it is more specific, sensitive and reliable. 相似文献
8.
Aging biology is intimately associated with dysregulated metabolism, which is one of the hallmarks of aging. Aging‐related pathways such as mTOR and AMPK, which are major targets of anti‐aging interventions including rapamcyin, metformin, and exercise, either directly regulate or intersect with metabolic pathways. In this review, numerous candidate bio‐markers of aging that have emerged using metabolomics are outlined. Metabolomics studies also reveal that not all metabolites are created equally. A set of core “hub” metabolites are emerging as central mediators of aging. The hub metabolites reviewed here are nicotinamide adenine dinucleotide, reduced nicotinamide dinucleotide phosphate, α‐ketoglutarate, and β‐hydroxybutyrate. These “hub” metabolites have signaling and epigenetic roles along with their canonical roles as co‐factors or intermediates of carbon metabolism. Together these hub metabolites suggest a central role of the TCA cycle in signaling and metabolic dysregulation associated with aging. 相似文献
9.
Arjun H. Ananth Natarajan Manikandan Ravi Kumar Rajan Ramakrishnan Elancheran Kunasekaran Lakshmithendral Muthiah Ramanathan Atanu Bhattacharjee Senthamaraikannan Kabilan 《化学与生物多样性》2020,17(2)
Breast Cancer (BCa) is the most often diagnosed cancer among women who were in the late 1940’s. Breast cancer growth is largely dependent on the expression of estrogen and progesterone receptor. Breast cancer cells may have one, both, or none of these receptors. The treatment for breast cancer may involve surgery, hormonal therapy (Tamoxifen, an aromatase inhibitor, etc.) and oral chemotherapeutic drugs. The molecular docking technique reported the findings on the potential binding modes of the 2‐(2‐bromo‐3‐nitrophenyl)‐5‐phenyl‐1,3,4‐oxadiazole derivatives with the estrogen receptor (PDB ID: 3ERT). The 1,3,4‐oxadiazole derivatives 4a – 4j have been synthesized and described by spectroscopic method. 2‐(2‐Bromo‐6‐nitrophenyl)‐5‐(4‐bromophenyl)‐1,3,4‐oxadiazole ( 4c ) was reconfirmed by single‐crystal XRD. All the compounds have been tested in combination with generic Imatinib pharmaceutical drug against breast cancer cell lines isolated from Caucasian woman MCF‐7, MDA‐MB‐453 and MCF‐10A non‐cancer cell lines. The compounds with the methoxy (in 4c ) and methyl (in 4j ) substitution were shown to have significant cytotoxicity, with 4c showing dose‐dependent activation and decreased cell viability. The mechanism of action was reported by induced apoptosis and tested by a DNA enzyme inhibitor experiment (ELISA) for Methyl Transferase. Molecular dynamics simulations were made for hit molecule 4c to study the stability and interaction of the protein?ligand complex. The toxicity properties of ADME were calculated for all the compounds. All these results provide essential information for further clinical trials. 相似文献