首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2173篇
  免费   126篇
  国内免费   4篇
耳鼻咽喉   13篇
儿科学   114篇
妇产科学   24篇
基础医学   289篇
口腔科学   29篇
临床医学   145篇
内科学   478篇
皮肤病学   102篇
神经病学   97篇
特种医学   37篇
外科学   228篇
综合类   103篇
一般理论   1篇
预防医学   140篇
眼科学   110篇
药学   217篇
中国医学   22篇
肿瘤学   154篇
  2023年   22篇
  2022年   35篇
  2021年   80篇
  2020年   47篇
  2019年   44篇
  2018年   53篇
  2017年   53篇
  2016年   70篇
  2015年   69篇
  2014年   102篇
  2013年   111篇
  2012年   180篇
  2011年   199篇
  2010年   131篇
  2009年   99篇
  2008年   121篇
  2007年   129篇
  2006年   123篇
  2005年   123篇
  2004年   132篇
  2003年   80篇
  2002年   88篇
  2001年   26篇
  2000年   24篇
  1999年   26篇
  1998年   11篇
  1997年   8篇
  1996年   8篇
  1995年   7篇
  1994年   7篇
  1993年   3篇
  1992年   7篇
  1991年   8篇
  1990年   10篇
  1989年   8篇
  1988年   7篇
  1987年   12篇
  1986年   6篇
  1985年   3篇
  1983年   6篇
  1982年   4篇
  1981年   2篇
  1979年   2篇
  1978年   2篇
  1973年   3篇
  1971年   3篇
  1967年   1篇
  1965年   1篇
  1932年   1篇
  1926年   1篇
排序方式: 共有2303条查询结果,搜索用时 15 毫秒
11.
Summary. A sandwich ELISA test using PPR specific monoclonal antibody (clone 4G6) to an epitope of nucleocapsid protein has been developed. The test uses polyclonal sera to capture the antigen from clinical samples (swabs and tissues). Captured antigens from clinical samples are detected using PPR specific monoclonal antibody. The test is specific to PPR as it failed to detect rinderpest vaccine virus (RBOK strain). Varieties of clinical samples originating from laboratory experiments (n=231) and from field (n=259) were employed to test the efficacy of sandwich-ELISA test. The test compared very well with an internationally accepted commercial Immune-capture ELISA kit, which uses biotinylated monoclonal antibody against the nucleocapsid protein. On a parallel testing using 490 clinical samples, 4G6 MAb based sandwich ELISA had an overall relative diagnostic specificity of 92.8% and diagnostic sensitivity of 88.9% compared to the commercial kit. The newly developed test is free from prozone phenomenon. PPR outbreaks from various parts of India have been confirmed using the test. Findings suggested that the newly developed ELISA is suitable for PPR diagnosis under field conditions.  相似文献   
12.
Inflammation: the link between insulin resistance, obesity and diabetes   总被引:41,自引:0,他引:41  
Recent data have revealed that the plasma concentration of inflammatory mediators, such as tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), is increased in the insulin resistant states of obesity and type 2 diabetes, raising questions about the mechanisms underlying inflammation in these two conditions. It is also intriguing that an increase in inflammatory mediators or indices predicts the future development of obesity and diabetes. Two mechanisms might be involved in the pathogenesis of inflammation. Firstly, glucose and macronutrient intake causes oxidative stress and inflammatory changes. Chronic overnutrition (obesity) might thus be a proinflammatory state with oxidative stress. Secondly, the increased concentrations of TNF-alpha and IL-6, associated with obesity and type 2 diabetes, might interfere with insulin action by suppressing insulin signal transduction. This might interfere with the anti-inflammatory effect of insulin, which in turn might promote inflammation.  相似文献   
13.
14.
Gamma interferon (IFN-gamma) is an important mediator of endotoxin (lipopolysaccharide [LPS])-induced immune responses. However, the specific cell types that produce IFN-gamma in response to LPS and the cellular factors that regulate LPS-induced IFN-gamma production have not been fully determined. The present studies were undertaken to characterize the cell populations that produce IFN-gamma after LPS challenge in the spleens of mice and to determine the regulatory factors that modulate LPS-induced production of IFN-gamma. Our studies show that the levels of splenic IFN-gamma mRNA and protein production peak at 6 and 8 h, respectively, after systemic LPS challenge. Approximately 60% of IFN-gamma-producing cells are natural killer (NK) cells (CD3(-)DX5(+)) and 25% are NKT cells (CD3(+)DX5(+)). Most of the remaining IFN-gamma-producing cells are T cells (CD3(+)DX5(-)), macrophages, and dendritic cells. Functionally, interleukin-12 (IL-12) is the major IFN-gamma-stimulating factor after LPS challenge, with costimulation provided by IL-15, IL-18, and B7 proteins. IL-10 is a major inhibitor of LPS-induced IFN-gamma production. Unlike intact heat-killed gram-negative and gram-positive bacteria, the class II major histocompatibility complex did not play a functional role in LPS-induced IFN-gamma production. LPS is a potent stimulus for splenic IL-10, IL-12 p40, and IL-15 mRNA expression, whereas IL-12 p35 and IL-18 mRNAs, as well as B7 proteins, are constitutively expressed in the mouse spleen. Of the factors studied, IL-18 serves as the most potent costimulus with IL-12 for IFN-gamma production, followed by IL-15 and B7 proteins. These data demonstrate that NK cells and NKT cells are the most abundant IFN-gamma-producing cells in the mouse spleen after LPS challenge and that IL-10 and IL-12 are key functional regulators of LPS-induced IFN-gamma production.  相似文献   
15.
Rheumatic heart disease is a significant clinical entity in young children, especially in the developing world. One of the major long-term effects of ill managed rheumatic fever is irreversible damage to the cardiac valve leaflets, primarily on the left side. With the limited success of currently available mechanical and bioprosthetic valves, there is an urgent need for new directions in bioprosthetic valves, both in material, including source, degree of fixation, surface, bulk modifications, etc., and design. In the present paper, new proposals in the material selection and fabrication of bioprosthetic valves are proposed based on electron microscopic studies of natural valve leaflets and the pericardial surface. Current approaches for bioprosthetic valve fabrications include the wide use of the pericardium as a leaflet material. The present study indicates a need for nondestructive surface examination of pericardial sheets for the elimination of areas of surface voids resulting from gross fiber disorientation. Also, there seems to be a need for incorporation of an in situ fiber renewal mechanism in bioprosthetic leaflets to emulate the natural valve more closely. Apparently natural leaflets have built-in fiber renewal mechanism(s).  相似文献   
16.
Otitis media with effusion is one of the commonest otological problems in paediatric age group. The condition occurs in childhood as overt or covert hearing loss presenting as an educational or behavioural problem. As there is widespread controversy regarding its precise aetiology, natural history and pathogenesis a treatment dilemma still persists. The main goal of this study is to compare the efficacy of different modalities of medical and surgical treatment designed for this condition and analysis of the results statistical.  相似文献   
17.
PURPOSE: Flavopiridol has in vitro activity in chronic lymphocytic leukemia (CLL) and promotes apoptosis independent of p53 function or prior fludarabine exposure. We sought to determine if flavopiridol has activity in previously treated CLL using two schedules of administration. PATIENTS AND METHODS: Patients with previously treated CLL were enrolled in two sequentially done phase II studies. Patients in the first trial received flavopiridol (50 mg/m(2)/d) as a continuous infusion (CI) for 72 hours every 2 weeks. Patients in the second trial received flavopiridol 50 mg/m(2) as a 1-hour bolus (IVB) daily for 3 days repeated every 3 weeks. Patients received up to 12 (CI cohort) or 8 (IVB cohort) cycles of therapy. RESULTS: Fifteen patients were enrolled in the 72-hour CI phase II trial; 6 (40%) had intermediate-risk (Rai stage I or II) and 9 (60%) had high-risk (Rai stage III and IV) stages. No responses were noted in this group; 27% had stable disease and 73% had progressive disease. Thirty-six patients were enrolled in the second IVB trial, with 13 (36%) having intermediate and 23 (64%) having high-risk disease. Four patients (11%) had partial responses, 19 (53%) had stable disease, and 13 (36%) had progressive disease. The progression-free survival for responders in the IVB trial was 3, 3, 9, and 19 months. The median progression-free survival was 2 months [95% confidence interval (95% CI), 1.8-3.8] for patients in the CI trial and 3 months (95% CI, 2.5-7.4) for the IVB trial. The median overall survival was 27 months (95% CI, 20-42) for the CI trial and 24 months (95% CI, 18-31) for the IVB trial. Toxicity was manageable and included mainly myelosuppression, infections, diarrhea, and fatigue. CONCLUSIONS: Flavopiridol has modest, schedule-dependent clinical activity in relapsed CLL and warrants future investigation utilizing alternative schedules of administration.  相似文献   
18.
AIM: To study the antitumor effect and antioxidant role of Bauhinia racemosa. METHODS: Antitumor activity and antioxidant status of methanol extract (50, 100, and 200 mg/kg) of Bauhinia racemosa stem bark was evaluated against Ehrlich ascites carcinoma (EAC) tumor in mice. Acute and short-term toxicity studies were performed initially in order to ascertain the safety of methanol extract of Bauhinia racemosa (MEBR). After 24 h of tumor inoculation, the extract was administered daily for 14 d. After administration of the last dose followed by 18 h fasting, mice were then sacrificed for observation of antitumor activity. The effect of MEBR on the growth of transplantable murine tumor, life span of EAC bearing hosts and simultaneous alterations in the hematological profile and liver biochemical parameters (lipid peroxidation, antioxidant enzymes) were estimated. RESULTS: The MEBR showed decrease in tumor volume, packed cell volume and viable cell count, and increased the nonviable cell count and mean survival time thereby increasing life span of EAC tumor bearing mice. Hematological profile reverted to more or less normal levels in extract treated mice. Treatment with MEBR decreased the levels of lipid peroxidation and increased the levels of glutathione, superoxide dismutase and catalase. CONCLUSION: The methanol extract of Bauhinia racemosa stem bark exhibited antitumor effect by modulating lipid peroxidation and augmenting antioxidant defense system in EAC bearing mice.  相似文献   
19.
The goal of this study was to determine the coefficient of permeability as well as the rate of carbonation of concrete constructed with rice husk ash (RHA) as a partial replacement for cement (i.e., 5%, 10%, and 15%) and two different concentrations of soap solutions (i.e., 1 percent and 2 percent). The microstructural studies of RHA, and carbonated samples have been conducted by using Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) analysis. According to this study, the carbonation depth of concrete made with 1% and 2% soap solution concentration and without rice husk ash decreased by 11.89% and 46.55%, respectively. From the results, it may also be observed that the carbonation depth of concrete made with up to 10% replacement of cement by rice husk ash led to maximum carbonation resistance, while more than 10% replacement of cement showed higher carbonation depth. It is also observed that the coefficient of permeability of concrete with 2% soap solution significantly decreased as compared to the 1% soap solution and control mix. It may be observed from the SEM images that 0% soap solution (M1) concrete has a very rough concrete surface which may indicate more voids. However, 2% soap solution concrete has a much smoother surface, which indicates a smaller number of voids. Furthermore, the SEM images showed that the soap solution helps in filling the voids of concrete which ultimately helps in reduction in permeability. Energy Dispersive X-Ray Analysis (EDX) of concrete with 0% (M1) and 2% (M6) soap solution disclosed that the concrete with 2% soap solution (M6) exhibited more silica element formation than the concrete with no soap solution (M1).  相似文献   
20.
Background:Dogs are the favorite companion animals among humans. The close interaction between dogs and people increases the risk of antibiotic resistance spreading. Surveillance for antimicrobial resistance and the identification of ESBL-producing Escherichia coli as an indicator bacterium is an important tool for managing antimicrobial drug therapy. Aims:The present study targeted to identify and characterize ESBL-producing E. coli among dogs suffering from diarrhea in and around Kolkata. Methods:Isolation and identification of E. coli from dogs suffering from diarrhea (n=70) along with screening for the production of both ESBL and AmpC. The isolates were further characterized through antimicrobial resistance profiling, resistance genes (blaCTX-M, blaTEM, and blaSHV) screening, and phylogenetic group study. Results:Among the 70 isolates, 21 (30%) were confirmed ESBL producers. An antibiogram typing of ESBL-producing E. coli revealed that the majority of them were resistant to norfloxacin (85.7%) followed by tetracycline (61.90%), doxycycline (57.14%), piperacillin/tazobactam (52.38%), cotrimoxazole (47.62%), gentamicin (42.62%), amikacin (23.81%), and chloramphenicol (19.05%). Major resistance genes included blaCTX-M (100%), blaTEM (28.57%), and blaSHV (9.50%). The predominant phylogenetic groups were phylogroup A (76%) followed by phylogroup D (24%). Conclusion:The current investigation reported a high prevalence of both ESBL and AmpC β-lactamase (AmpC) producing E. coli, co-resistance to a distinct group of antibiotics, and co-existence of different ESBL genes in dogs. Our findings highlight the importance of diagnostic antimicrobial susceptibility testing for proper antimicrobial therapy and to prevent antimicrobial resistance from spreading to humans from dogs in Kolkata and the surrounding area.Key Words: Antibiotics, Dog, E. coli, ESBL, PCR  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号