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   525篇
  免费   26篇
  国内免费   2篇
耳鼻咽喉   20篇
儿科学   26篇
妇产科学   6篇
基础医学   64篇
口腔科学   8篇
临床医学   21篇
内科学   95篇
皮肤病学   22篇
神经病学   11篇
特种医学   17篇
外科学   100篇
综合类   17篇
预防医学   22篇
眼科学   13篇
药学   51篇
中国医学   6篇
肿瘤学   54篇
  2023年   2篇
  2022年   9篇
  2021年   14篇
  2020年   15篇
  2019年   10篇
  2018年   14篇
  2017年   13篇
  2016年   17篇
  2015年   20篇
  2014年   14篇
  2013年   15篇
  2012年   47篇
  2011年   47篇
  2010年   17篇
  2009年   17篇
  2008年   39篇
  2007年   24篇
  2006年   26篇
  2005年   17篇
  2004年   25篇
  2003年   7篇
  2002年   17篇
  2001年   15篇
  2000年   16篇
  1999年   15篇
  1998年   6篇
  1997年   6篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1992年   6篇
  1991年   6篇
  1990年   7篇
  1989年   11篇
  1988年   4篇
  1987年   4篇
  1986年   4篇
  1985年   4篇
  1984年   5篇
  1983年   9篇
  1982年   2篇
  1979年   2篇
排序方式: 共有553条查询结果,搜索用时 0 毫秒
61.
ObjectiveTo identify the possible antiplasmodial compounds from leaf, stem, root and flower extracts of Ocimum canum (O. canum), Ocimum sanctum (O. sanctum) and Ocimum basilicum (O. basilicum).MethodsThe O. canum, O. sanctum and O. basilicum were collected from Ramanathapuram District, Tamil Nadu and the extraction was carried out in ethanol. The filter sterilized extracts (100, 50, 25, 12.5, 6.25 and 3.125 μg/mL) of leaf, stem, root and flower extracts of O. canum, O. sanctum and O. basilicum were tested for antiplasmodial activity against Plasmodium falciparum (P. falciparum). The potential extracts were also tested for their phytochemical constituents.ResultsThe leaf extract of O. sanctum showed excellent antiplasmodial activity (IC50 35.58 μg/mL) followed by leaf extract of O. basilicum (IC50 43.81 μg/mL). The leaf extract of O. canum, root extracts of O. sanctum and O. basilicum, the stem and flower extracts of all the three tested Ocimum species showed IC50 values between 50 and 100 μg/mL. Statistical analysis reveals that, significant antiplasmodial activity (P <0.01) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes was also carried out and it shows that, there were no morphological changes in erythrocytes by the ethanolic extract of O. canum, O. sanctum and O. basilicum. The in vitro antiplasmodial activity might be due to the presence of alkaloids, glycosides, flavonoids, phenols, saponins, triterpenoids, proteins, resins, steroids and tannins in the ethanolic extracts of tested plants.ConclusionsThe ethanolic leaf extracts of O. sanctum possess lead compounds for the development of antiplasmodial drugs.  相似文献   
62.
ObjectiveTo investigate the antibacterial properties of the five metal oxide nanoparticles viz., Al2O3, Fe2O3, CeO2, ZrO2 and MgO against urinary tract infectious pathogens viz., Pseudomonas sp., Enterobacter sp., Klebsiella sp., Escherichia coli (E. coli), Proteus morganii (P. morganii) and Staphylococcus aureus (S. aureus).MethodsThe antibacterial activity of the five different nanoparticles was assessed by well diffusion method. Different concentrations of the nanoparticles were analyzed by minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) techniques. Finally, the potential nanoparticle Al2O3 which showed maximum antibacterial sensitivity was also subjected for the time kill assay method.ResultsAmong the nanoparticles, Al2O3 nanoparticle showed maximum sensitivity (16.00±0.21) mm against E. coli. None of the nanoparticles showed activity against Pseudomonas sp. The MIC results also revealed that, the Al2O3 nanoparticle showed maximum inhibition at the concentration of 5 μg/mL against E. coli, followed by 10 μg/mL against Klebsiella sp. and P. morganii, respectively. Moreover, the time kill assay revealed that, the bacterial growth was maximum inhibited at the concentration of 5 μg/mL from the 2nd h.ConclusionsIt can be concluded from the present findings that, the Al2O3 nanoparticle can be used as an alternative antibacterial agent for the urinary bacterial diseases after completing successful clinical trials.  相似文献   
63.
ObjectiveTo identify the possible antiplasmodial drugs from bacteria associated with marine sponge Stylissa carteri (S. carteri).MethodsThe S. carteri samples were collected from Thondi coast and subjected for enumeration and isolation of associated bacteria. Filter sterilized extracts (100, 50, 25, 12.5, 6.25 and 3.125 μ g/mL) from isolated bacterial strains were screened for antiplasmodial activity against Plasmodium falciparum (P. falciparum) and potential extracts were also screened for biochemical constituents.ResultsTwelve samples of S. carteri were collected and subjected for enumeration and isolation of associated bacteria. The count of bacterial strains were maximum in November 2007 (34 × 104 CFU/g) and the average count was maximum during the monsoon season (203 × 103 CFU/g). Thirty two morphologically different bacterial strains were isolated from S. carteri and the ethyl acetate bacterial extracts were screened for antiplasmodial activity against P. falciparum. The antiplasmodial activity of a strain THB17 (IC50 20.56 μ g/mL) extract is highly comparable with the positive control chloroquine (IC50 19.59 μ g/mL) and 13 bacterial extracts which showed IC50 value of more than 100 μ g/mL. Statistical analysis reveals that, significant in vitro antiplasmodial activity (P<0.05) was observed between the concentrations and time of exposure. The chemical injury to erythrocytes showed no morphological changes in erythrocytes by the ethyl acetate extract of bacterial strains after 48 h of incubation. The in vitro antiplasmodial activity might be due to the presence of reducing sugars and alkaloids in the ethyl acetate extracts of bacterial strains.ConclusionsThe ethyl acetate extract of THB17 possesses lead compounds for the development of antiplasmodial drugs.  相似文献   
64.
Rheumatoid arthritis (RA) is a systemic autoimmune disease that is associated with immunologic alterations in T cells and B cells. Moreover, many of the agents used in RA patients are potentially immunosuppressive. Thus, the underlying disease and treatment may both increase the susceptibility to infections and decrease vaccine responses. With the growing use of aggressive therapies for RA, including anti-tumor necrosis factor agents and newer biologic therapies such as rituximab and abatacept, an increasing concern will be that patients may not respond to conventional vaccination. Further prospective studies on response to vaccination are needed to answer this important public health question. Nevertheless, it is already clear that vaccination does induce response in many patients. Unfortunately, vaccination is underutilized in RA patients and needs to be aggressively promoted.  相似文献   
65.
Cell surface receptors for laminin may play an important role in tumor migration and metastasis. To evaluate laminin receptor/laminin-binding protein expression in human colon carcinoma, surgical specimens of primary colon cancers and liver metastases were examined by blot hybridization of total RNA with a complementary DNA clone which encodes a Mr 32,000 human laminin-binding protein. The mRNA level of the laminin-binding protein was higher in primary colon carcinoma than in adjacent normal colonic epithelium in 20 of 21 cases. In all 6 cases of colon cancer liver metastases, the laminin-binding protein mRNA level was more than 3-fold greater in tumor than in adjacent normal liver tissue. The tumor/normal ratio of this laminin-binding protein mRNA expression in primary colon cancer has significant correlation with Dukes' classification (P less than 0.001). Our results suggest that mRNA expression of the laminin-binding protein may be a marker of human colorectal cancer progression and biological aggressiveness.  相似文献   
66.
PURPOSE: To analyze backscattered dose enhancements near different metallic interfaces for cobalt-60 ((60)Co) gamma rays and 6- and 18-MV photon beams. MATERIAL AND METHODS: Measurements were carried out with a PTW thin-window, parallel-plate ionization chamber and an RDM-1F electrometer. Thin sheets of aluminum, mild steel, copper, cadmium and lead were used as inhomogeneities. The chamber was positioned below the inhomogenities with the gantry maintained under the couch. RESULTS: It can be noticed that the backscatter dose factor (BSDF) reaches the saturation value within few millimeters of all inhomogeneities and the thickness at which the saturation value is reached depends on the atomic number of the inhomogeneity. The amount of backscattered radiation was noticed to be greater with lesser-energy photons ((60)Co) compared to the high erenergy photons. The BSDF varies across the beam when the inhomogeneity is present due to the change in beam quality. The backscattered electrons from lead inhomogeneity have a range in the order of 5-7 mm. CONCLUSION: Higher atomic number inhomogeneities result in an increase in BSDF, as they have higher scattering cross section for the secondary electrons. The increase in dose was noticed for few millimeters upstream from the metallic inhomogeneity, which suggests that the range of backscattered electrons is very small. Since the factors affecting the BSDF at the interface are energy dependent, it is expected that the variation in BSDF will also be sensitive to the beam energy.  相似文献   
67.
A novel colorimetric sensing platform using the peroxidase mimicking activity of ternary MoS2-loaded ZnO–g-C3N4 nanocomposites (ZnO–g-C3N4/MoS2) has been developed for the determination of Hg(ii) ions over co-existing metal ions. The nanocomposite was prepared using an exfoliation process, and the product was further characterized using SEM, TEM, XRD and FTIR analysis. The ZnO–g-C3N4/MoS2 possesses excellent intrinsic catalytic activity to induce the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in aqueous solution in the presence of H2O2 to generate deep blue coloured cation radicals (TMB+) which can be viewed with the naked eye and produce absorbance at a wavelength of 652 nm. The addition of a well known bioradical scavenger, glutathione (GSH), to the solution hinders the generation of cation radicals and turns the solution colourless. The introduction of Hg(ii) to this solution brings the blue colour back into it, due to the strong affinity of the thiol in the GSH. Based on this mechanism, we have developed a simple and rapid colorimetric sensor for the highly sensitive and selective detection of Hg(ii) ions in aqueous solution with a low detection limit of 1.9 nM. Furthermore, the prepared colorimetric sensor was effectively applied for the quantification analysis of real water samples.

A novel colorimetric sensing platform using the peroxidase mimicking activity of ternary MoS2-loaded ZnO–g-C3N4 nanocomposites (ZnO–g-C3N4/MoS2) has been developed for the determination of Hg(ii) ions over co-existing metal ions.  相似文献   
68.
69.
70.
Herein we report a rare case of a large uterine neurofibroma. The patient reported infertility and nonspecific pelvic symptoms. Physical examination and ultrasonography revealed a mass of uterine origin with echo texture similar to that of a myoma. With a provisional diagnosis of a myomatous uterus, laparoscopic myomectomy was attempted. The mass, which measured 13 × 9 × 8 cm, was noted to be arising from the uterine fundus and extending into the left broad ligament. Histopathologic examination revealed a neurofibroma, which was confirmed at immunohistochemical analysis of the specimen. Most neurofibromas arise as subcutaneous swellings, and large neurofibromas arising from the myometrium are rare. Deep-tissue neurofibromas are known to recur and are associated with a higher probability of becoming malignant.  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