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   1443篇
  免费   70篇
  国内免费   7篇
耳鼻咽喉   11篇
儿科学   117篇
妇产科学   37篇
基础医学   245篇
口腔科学   49篇
临床医学   102篇
内科学   289篇
皮肤病学   22篇
神经病学   78篇
特种医学   39篇
外科学   124篇
综合类   30篇
一般理论   1篇
预防医学   80篇
眼科学   64篇
药学   118篇
中国医学   7篇
肿瘤学   107篇
  2024年   1篇
  2023年   9篇
  2022年   32篇
  2021年   52篇
  2020年   25篇
  2019年   31篇
  2018年   61篇
  2017年   40篇
  2016年   50篇
  2015年   46篇
  2014年   67篇
  2013年   71篇
  2012年   128篇
  2011年   138篇
  2010年   74篇
  2009年   68篇
  2008年   109篇
  2007年   111篇
  2006年   82篇
  2005年   83篇
  2004年   68篇
  2003年   52篇
  2002年   36篇
  2001年   9篇
  2000年   13篇
  1999年   18篇
  1998年   13篇
  1997年   8篇
  1995年   3篇
  1994年   1篇
  1993年   2篇
  1991年   1篇
  1990年   3篇
  1989年   3篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1981年   2篇
  1979年   1篇
  1977年   3篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
排序方式: 共有1520条查询结果,搜索用时 15 毫秒
81.
Allergic bronchopulmonary aspergillosis (ABPA) is caused by a dominant Th2 immune response to antigens derived from the opportunistic mold Aspergillus, most commonly Aspergillus fumigatus. It occurs in 4%–15% of patients with cystic fibrosis (CF); however, not all patients with CF infected with A. fumigatus develop ABPA. Therefore, we compared cohorts of A. fumigatus–colonized CF patients with and without ABPA to identify factors mediating tolerance versus sensitization. We found that the costimulatory molecule OX40 ligand (OX40L) was critical in driving Th2 responses to A. fumigatus in peripheral CD4+ T cells isolated from patients with ABPA. In contrast, CD4+ T cells from the non-ABPA cohort did not mount enhanced Th2 responses in vitro and contained a higher frequency of TGF-β–expressing regulatory T cells. Heightened Th2 reactivity in the ABPA cohort correlated with lower mean serum vitamin D levels. Further, in vitro addition of 1,25 OH-vitamin D3 substantially reduced DC expression of OX40L and increased DC expression of TGF-β. This in vitro treatment also resulted in increased Treg TGF-β expression and reduced Th2 responses by CD4+ T cells from patients with ABPA. These data provide rationale for a therapeutic trial of vitamin D to prevent or treat ABPA in patients with CF.  相似文献   
82.
Sentinel lymph node biopsy has attained "standard of care' status in the management of breast carcinoma. However, the pathological interpretation and clinical consequences of "minimally involved' sentinel lymph nodes remain controversial. Herein, we present some of the complex and challenging pathological problems inherent in this evolving setting. Clearly, at least some of our current concepts regarding "minimally involved' sentinel lymph nodes need reappraisal.  相似文献   
83.
84.
We have reported earlier that Aspergillus fumigatus is inhibited in vitro by Candida albicans which also interferes in its isolation from sputum experimentally seeded with predetermined graded inocula of the two fungi. It was further shown that this interference was neutralized by employing peptone glucose agar with incorporation of fluconazole which is more inhibitory to C. albicans than to A. fumigatus. This communication embodies the results of evaluation of peptone glucose fluconazole agar (PGFA) as a selective culture medium for rapid and enhanced isolation of A. fumigatus from sputum of patients clinically suspected of aspergillosis with C. albicans colonization in the respiratory tract. Of the 23 sputum specimens and one broncho-alveolar lavage collected from 15 suspected aspergillosis patients, A. fumigatus was isolated from all (100%) on PGFA as against only 19 specimens (79%) that proved to be positive on the control PGA medium (P<0.05). The greater efficacy of PGFA than that of PGA was further evident from the 2-fold higher A. fumigatus mean colony count (8.2+/-1.87) on the former medium than on the latter (3.7+/-1.00), and this difference was found to be statistically significant (P<0.05). Besides, A. fumigatus colonies were macroscopically recognizable within 2-3 days on PGFA at 28 degrees C in strong contrast to 5-7 days required on PGA. Based upon these observations, PGFA is recommended for wider application as a selective medium for rapid and enhanced recovery of A. fumigatus from sputum of patients clinically suspected of aspergillosis with C. albicans colonization in their respiratory tract.  相似文献   
85.
Hirano S  Anuradha CD  Kanno S 《Immunology》2002,107(1):86-92
Macrophages are known to adhere to a plastic dish via beta2 integrin (CR3) and scavenger receptors. Although their functions such as phagocytosis, endocytosis, and nitric oxide production have been investigated on adherent macrophages in vitro, very little is known about intracellular signals triggered by adhesion to a plastic dish. Recently we reported that the mRNA level of krox-20/egr-2 was significantly increased in rat alveolar macrophages following exposure to fibrous titanium dioxide particles. In the present study we report that up-regulation of krox-20/egr-2 gene expression following adhesion to a plastic dish and homophilic adhesion in rat alveolar macrophages and rat macrophage cell line, NR8383. The mRNA level of krox-20/egr-2 increased with a peak 1 hr after adhesion to a plastic dish in both cell types. Piceatannol inhibited tyrosine-phosphorylation of Syk and decreased both adhesion and krox-20/egr-2 mRNA level. In contrast staurosporine, a serine/threonine kinase inhibitor, increased adherence of macrophages and yet prohibited the adhesion-dependent increase in krox-20/egr-2 gene expression. When NR8383 cells are cultured in suspension, the cells aggregated naturally and produced cell clumps. The mRNA level of krox-20/egr-2 also increased in response to the homophilic intercellular adhesion. The increased mRNA level of krox-20/egr-2 was not caused by inflammatory stimuli, because lipopolysaccharide did not affect the aggregation-dependent up-regulation of krox-20/egr-2 gene. The up-regulation of krox-20/egr-2 gene due to the homophilic cell aggregation was also inhibited either by piceatannol or staurosporine. Those results suggest that krox-20/egr-2 gene expression is triggered by sensing non-specific and homophilic cellular adhesion and the following phosphorylation of signal transducing proteins including Syk and staurosporine-inhibitable kinases.  相似文献   
86.
Laboratory diagnosis is the mainstay in the diagnosis of HIV infection in an individual. The wide range of diagnostic kits available, for the detection of anti HIV antibodies, makes it mandatory that the kits are evaluated before they are made available in the market. We evaluated the performance of a Microlisa HIV kit (J. Mitra & Co.) using a panel of HIV reactive and non reactive clinical specimens. The sensitivity and specificity of the kit were found to be 100% as compared to the UBI HIV 1/2 EIA kit. The ease of testing, the assay characteristics including efficiency of the Microlisa favour its use by laboratories as a primary screen for HIV infection.  相似文献   
87.
Choleraphage φ149 DNA is a linear double-stranded molecule 69 × 106 Da or 104 kilobase pairs (kbp). From restriction enzyme analysis, it has been concluded that the DNA is circularly permuted. There are at least three S1 nuclease-sensitive sites along the length of the molecule. These sites represent single-strand interruptions repairable by T4 DNA ligase. A physical map of the DNA has been constructed using the restriction endonucleases BamH1 and BglII.  相似文献   
88.
The kinetics and mechanism of the inhibiting action of toluene on the Ce(IV) initiated polymerization of acrylonitrile were studied together with the effects of [M], [Ce(IV)], [Toluene], [HClO4], [NaClO4], and [Acetic acid] on the rate of polymerization. The values of composite rate constant kkt/kpkoki for toluene (and substituted toluenes) was calculated by plotting [M]/Rp versus [M]?1. A very significant observation in the present study was that the plot of [M]/Rp versus [M]?1 gave a negative intercept, which seems to be a general observation for all inhibiting substrates. On the basis of the experimental data, it could be concluded that the benzyl radical obtained by hydrogen abstraction, and not a chain transfer, is responsible for the inhibition.  相似文献   
89.
This study was performed to determine the maximum tolerated dose (MTD) and therapeutic effects of rhenium-186 ((186)Re)-labeled liposomal doxorubicin (Doxil), investigate associated toxicities, and calculate radiation absorbed dose in head and neck tumor xenografts and normal organs. Doxil and control polyethylene glycol (PEG)-liposomes were labeled using (186)Re-N,N-bis(2-mercaptoethyl)-N',N'-diethylethylenediamine (BMEDA) method. Tumor-bearing rats received either no therapy (n=6), intravenous Doxil (n=4), or escalating radioactivity of (186)Re-Doxil (185-925?MBq/kg) or (186)Re-PEG-liposomes (1110-1665?MBq/kg) and were monitored for 28 days. Based on body weight loss and systemic toxicity, MTD for (186)Re-Doxil and (186)Re-PEG-liposomes were established at injected radioactivity/body weight of 740 and 1480?MBq/kg, respectively. (186)Re-injected radioactivity/body weight for therapy studies was determined to be 555?MBq/kg for (186)Re-Doxil and 1295?MBq/kg for (186)Re-PEG-liposomes. All groups recovered from their body weight loss, leucopenia, and thrombocytopenia by 28 days postinjection. Normalized radiation absorbed dose to tumor was significantly higher for (186)Re-Doxil (0.299±0.109 Gy/MBq) compared with (186)Re-PEG-liposomes (0.096±0.120 Gy/MBq) (p<0.05). In a separate therapy study, tumor volumes were significantly smaller for (186)Re-Doxil (555?MBq/kg) compared with (186)Re-PEG-liposomes (1295?MBq/kg) (p<0.01) at 42 days postinjection. In conclusion, combination chemoradionuclide therapy with (186)Re-Doxil has promising potential, because good tumor control was achieved with limited associated toxicity.  相似文献   
90.
A 11/2-year-old male child with past history of recurrent wheezing presented with a severe and refractory episode following a peanut aspiration. A bronchoscopy was done and the peanut removed. However, as the wheezing persisted a detailed evaluation was done which revealed a bronchogenic cyst. Surgical excision of the cyst was done and the child improved symptomatically. Congenital lesions need to be ruled out in infants and children with persistent and refractory wheezing  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