全文获取类型
收费全文 | 673篇 |
免费 | 53篇 |
国内免费 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 8篇 |
2018年 | 17篇 |
2017年 | 15篇 |
2016年 | 16篇 |
2015年 | 35篇 |
2014年 | 35篇 |
2013年 | 61篇 |
2012年 | 55篇 |
2011年 | 55篇 |
2010年 | 30篇 |
2009年 | 31篇 |
2008年 | 50篇 |
2007年 | 40篇 |
2006年 | 35篇 |
2005年 | 29篇 |
2004年 | 39篇 |
2003年 | 21篇 |
2002年 | 36篇 |
2001年 | 2篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1966年 | 1篇 |
1962年 | 2篇 |
排序方式: 共有727条查询结果,搜索用时 148 毫秒
31.
Jitendra Singh Manimuthu Mani Sankar Sandeep Kumar Krishnamurthy Gopinath Niti Singh Kalaivani Mani Sarman Singh 《PloS one》2013,8(7)
Background
Tuberculosis (TB), caused by Mycobacterium tuberculosis, is one of the leading causes of mortality and morbidity across all age groups throughout the world, especially in developing countries.Methodology/Principal Findings
In this study, we have included 432 open index cases with their 1608 household contacts in a prospective cohort study conducted from May 2007 to March 2009. The follow-up period was 2 years. All Index cases were diagnosed on the basis of suggestive signs and symptoms and sputum being AFB positive. Among the 432 index patients, 250 (57.9%) were males and 182 (42.1%) females; with mean age of 34±14.4 yr and 26±11.1 yr, respectively. Out of 1608 household contacts, 866 (53.9%) were males and 742 (46.1%) females; with mean age of 26.5±15.8 and 26.5±16.0 yr, respectively. Of the total 432 households, 304 (70.4%) had ≤4 members and 128 (29.6%) had ≥5 members. The median size of the family was four. Of the 1608 contacts, 1206 were able to provide sputum samples, of whom 83 (6.9%) were found MTB culture positive. Household contacts belonging to adult age group were predominantly (74, 89.2%) infected as compared to the children (9, 10.8%). On screening the contact relationship status with index patients, 52 (62.7%) were first-degree relatives, 18 (34.6%) second-degree relatives and 12 (14.5%) spouses who got infected from their respective index patients. Co-prevalent and incident tuberculosis was found in 52 (4.3%) and 31 (2.6%) contacts, respectively. In incident cases, the diagnosis could be made between 4 to 24 months of follow-up, after their baseline evaluation.Conclusion
Active household contact investigation is a powerful tool to detect and treat tuberculosis at early stages and the only method to control TB in high-TB-burden countries. 相似文献32.
Gunasekaran Suwarnalata Ai Huey Tan Hidayah Isa Ranganath Gudimella Arif Anwar Mun Fai Loke Sanjiv Mahadeva Shen-Yang Lim Jamuna Vadivelu 《PloS one》2016,11(4)
Parkinson''s disease (PD) is the second most common chronic and progressive neurodegenerative disorder. Its etiology remains elusive and at present only symptomatic treatments exists. Helicobacter pylori chronically colonizes the gastric mucosa of more than half of the global human population. Interestingly, H. pylori positivity has been found to be associated with greater of PD motor severity. In order to investigate the underlying cause of this association, the Sengenics Immunome protein array, which enables simultaneous screening for autoantibodies against 1636 human proteins, was used to screen the serum of 30 H. pylori-seropositive PD patients (case) and 30 age- and gender-matched H. pylori-seronegative PD patients (control) in this study. In total, 13 significant autoantibodies were identified and ranked, with 8 up-regulated and 5 down-regulated in the case group. Among autoantibodies found to be elevated in H. pylori-seropositive PD were included antibodies that recognize Nuclear factor I subtype A (NFIA), Platelet-derived growth factor B (PDGFB) and Eukaryotic translation initiation factor 4A3 (eIFA3). The presence of elevated autoantibodies against proteins essential for normal neurological functions suggest that immunomodulatory properties of H. pylori may explain the association between H. pylori positivity and greater PD motor severity. 相似文献
33.
Kumar Abhiram Jha Tapas C Nag Shashi Wadhwa Tara Sankar Roy 《Journal of biosciences》2016,41(4):667-676
Light causes damage to the retina, which is one of the supposed factors for age-related macular degeneration in human. Some animal species show drastic retinal changes when exposed to intense light (e.g. albino rats). Although birds have a pigmented retina, few reports indicated its susceptibility to light damage. To know how light influences a cone-dominated retina (as is the case with human), we examined the effects of moderate light intensity on the retina of white Leghorn chicks (Gallus g. domesticus). The newly hatched chicks were initially acclimatized at 500 lux for 7 days in 12 h light: 12 h dark cycles (12L:12D). From posthatch day (PH) 8 until PH 30, they were exposed to 2000 lux at 12L:12D, 18L:6D (prolonged light) and 24L:0D (constant light) conditions. The retinas were processed for transmission electron microscopy and the level of expressions of rhodopsin, S- and L/M cone opsins, and synaptic proteins (Synaptophysin and PSD-95) were determined by immunohistochemistry and Western blotting. Rearing in 24L:0D condition caused disorganization of photoreceptor outer segments. Consequently, there were significantly decreased expressions of opsins and synaptic proteins, compared to those seen in 12L:12D and 18L:6D conditions. Also, there were ultrastructural changes in outer and inner plexiform layer (OPL, IPL) of the retinas exposed to 24L:0D condition. Our data indicate that the cone-dominated chick retina is affected in constant light condition, with changes (decreased) in opsin levels. Also, photoreceptor alterations lead to an overall decrease in synaptic protein expressions in OPL and IPL and death of degenerated axonal processes in IPL. 相似文献
34.
35.
Detection of oestrous-related odour in bovine ( Bos taurus) saliva: bioassay of identified compounds
Sankar R Archunan G Habara Y 《Animal : an international journal of animal bioscience》2007,1(9):1321-1327
The present study was designed to identify the volatile constituents across the oestrous cycle of bovine in order to detect oestrous-specific chemical signal. The bovine saliva was extracted with diethyl ether (1 : 1 ratio, v/v) and analysed by gas chromatography-linked mass spectrometry. Numerous compounds were identified during oestrous cycle of bovine saliva. Among these, the compounds, namely, trimethylamine, acetic acid, phenol 4-propyl, pentanoic acid and propionic acid were specific to oestrous stage. The behaviour assay revealed that the compound, trimethylamine, is involved in attracting the male animal. The result concludes that the trimethylamine is considered as a putative oestrous-specific salivary chemo-signal in the bovine. 相似文献
36.
Suchismita Subadini Ram Sankar Panigrahy Nishesh Kumar Gupta Krishnendu Bera Harekrushna Sahoo 《Luminescence》2022,37(6):876-882
A comparative study of interaction between chicken egg white lysozyme (Lyz) with two hexavalent chromate ions; chromate and dichromate; which are prevalently known for their toxicity, was investigated using different spectroscopic techniques along with a molecular docking study. Both steady-state and time-resolved studies revealed that the addition of chromate/dichromate is responsible for strong quenching of intrinsic fluorescence in Lyz and the quenching is caused by both static and dynamic quenching mechanisms. Different binding and thermodynamic parameters were also calculated at different temperatures from the intrinsic fluorescence of Lyz. The conformational change in Lyz and thermodynamic parameters obtained during the course of interaction with chromate/dichromate were well-supported by the molecular docking results. 相似文献
37.
Redox-state dependent blinking of single photosystem I trimers at around liquid-nitrogen temperature
Efficient light harvesting in a photosynthetic antenna system is disturbed by a ragged and fluctuating energy landscape of the antenna pigments in response to the conformation dynamics of the protein. This situation is especially pronounced in Photosystem I (PSI) containing red shifted chlorophylls (red Chls) with the excitation energy much lower than the primary donor. The present study was conducted to clarify light-harvesting dynamics of PSI isolated from Synechocystis sp. PCC6803 by using single-molecule spectroscopy at liquid?nitrogen temperatures. Fluorescence emission at around 720?nm from the red Chls in single PSI trimers was monitored at 80–100?K. Intermittent variations in the emission intensities, so-called blinking, were frequently observed. Its time scale lay in several tens of seconds. The blinking amplitude depended on the redox state of the phylloquinone (A1). Electrochromic shifts of Chls induced by the negative charge on A1 were calculated based on the X-ray crystallographic structure. A Chl molecule, Chl-A839 (numbering according to PDB 5OY0), bound near A1 was found to have a large electrochromic shift. This Chl has strong exciton coupling with neighboring Chl (A838) whose site energy was predicted to be determined by interaction with an arginine residue (ArgF84) [Adolphs et al., 2010]. A possible scenario of the blinking was proposed. Conformational fluctuations of ArgF84 seesaw the excitation-energy of Chl-A838, which perturbs the branching ratio of excitation-energy between the red Chl and the cationic form of P700 as a quencher. The electrochromic shift of Chl-A839 enhances the effect of the conformation dynamics of ArgF84. 相似文献
38.
39.
Despite the existence of a preventative vaccine, HBV represents a substantial threat to public health, suggesting the need for research to develop new treatments to combat the disease. The authors review the available in vitro and in vivo models, including recently developed transgenic and chimeric mouse models. 相似文献
40.
Protoporphyrin IX and its derivatives are used as photosensitizers in the photodynamic therapy of cancer. Protoporphyrin IX
penetrates into human red blood cells and releases oxygen from them. This leads to a change in the morphology of the cells.
Spectrophotometric studies reveal that protoporphyrin IX interacts with haemoglobin and myoglobin forming ground state complexes.
For both proteins, the binding affinity constant decreases, while the possible number of binding sites increases, as the aggregation
state of the porphyrin is increased. The interactions lead to conformational changes of both haemoglobin and myoglobin as
observed in circular dichroism studies. Upon binding with the proteins, protoporphyrin IX releases the heme-bound oxygen from
the oxyproteins, which is dependent on the stoichiometric ratios of the porphyrin: protein. The peroxidase activities of haemoglobin
and myoglobin are potentiated by the protein-porphyrin complexation. Possible mechanisms underlying the relation between the
porphyrin-induced structural modifications of the heme proteins and alterations in their functional properties have been discussed.
The findings may have a role in establishing efficacy of therapeutic uses of porphyrins as well as in elucidating their mechanisms
of action as therapeutic agents. 相似文献