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   932篇
  免费   39篇
  国内免费   2篇
耳鼻咽喉   1篇
儿科学   56篇
妇产科学   15篇
基础医学   121篇
口腔科学   19篇
临床医学   75篇
内科学   143篇
皮肤病学   8篇
神经病学   100篇
特种医学   20篇
外科学   149篇
综合类   33篇
预防医学   44篇
眼科学   23篇
药学   58篇
中国医学   17篇
肿瘤学   91篇
  2023年   6篇
  2022年   19篇
  2021年   35篇
  2020年   10篇
  2019年   21篇
  2018年   33篇
  2017年   13篇
  2016年   16篇
  2015年   27篇
  2014年   23篇
  2013年   36篇
  2012年   55篇
  2011年   56篇
  2010年   33篇
  2009年   32篇
  2008年   32篇
  2007年   39篇
  2006年   33篇
  2005年   35篇
  2004年   42篇
  2003年   45篇
  2002年   34篇
  2001年   29篇
  2000年   25篇
  1999年   38篇
  1998年   13篇
  1996年   6篇
  1995年   11篇
  1994年   7篇
  1993年   6篇
  1992年   11篇
  1991年   11篇
  1990年   11篇
  1989年   10篇
  1988年   13篇
  1987年   7篇
  1986年   7篇
  1985年   6篇
  1984年   9篇
  1983年   7篇
  1981年   9篇
  1980年   6篇
  1979年   7篇
  1977年   4篇
  1975年   4篇
  1971年   3篇
  1961年   3篇
  1959年   4篇
  1958年   6篇
  1929年   3篇
排序方式: 共有973条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
In this study, the anti-inflammatory (in reference to the cardinal signs of inflammation) and other related pharmacological activities of the hot water extract of black tea (Camellia sinensis, Sikkim variety) were evaluated along with certain standard drugs. The extract showed significant inhibitory activity against carrageenin, histamine, serotonin and prostaglandin-induced pedal inflammation. The extract inhibited exudative inflammation. The tea extract also inhibited cotton pellet-induced granuloma formation and adjuvant-induced polyarthritis. Black tea extract showed significant inhibition against glucose oxidase-mediated inflammation. The present observations establish the efficacy of this particular variety of black tea, both in the exudative and proliferative forms and as well in the chronic phase of inflammation.  相似文献   
15.
A 2,5-disubstituted tetrazole with p-nitrophenyl and 3-pyridyl units as acceptors (1a), and three push–pull tetrazoles with p-nitrophenyl as an acceptor and phenyl (1b), 2-(dibenzo[b,d]furan-4-yl) (1c), and 4-(N,N-diphenylamino)phenyl (1d) as donor groups, were synthesized by copper-catalyzed aerobic C–N coupling of p-nitrophenyl tetrazole with appropriately substituted aryl boronic acids. The absorption and emission spectra of 1a–c showed minimal dependence on the polarity of the solvent; however, in the case of 1d a blue shift was noted in the longest absorption band (λ1) as the polarity increased. The fluorescence intensity of the title compounds was found to be solvent-dependent; however, no apparent correlation to solvent polarity could be established. The absorption and emission characteristics of 1a–d were also influenced by the nature of the substituent as 1d, bearing a strong electron donating 4-(N,N-diphenylamino)phenyl group, displayed a significant red shifted absorption (λ1) as well as emission (λem) bands compared to other compounds. Time dependent density functional calculations (CAM-B3LYP/6-311++G**) revealed that the longest wavelength band (λ1) is associated with an intramolecular charge transfer (ICT) from HOMO/HOMO-1/HOMO-2 → LUMO/LUMO+1 in these molecules. The first hyperpolarizability values, βHRS, of 1a–d were measured using the solution-based hyper-Rayleigh scattering technique using a femtosecond Ti:Sapphire laser and the highest NLO activity was measured for 1d with the greatest push–pull characteristics. A strong correlation was observed between the calculated hyperpolarizability (βtot) and experimentally measured values (βHRS).

A 2,5-disubstituted tetrazole with a p-nitrophenyl unit as an acceptor and a 4-(N,N-diphenylamino) phenyl group as a donor exhibits strong push–pull characteristics and displays high NLO activity.  相似文献   
16.
Aim:  The present study was carried out to analyze the maternal death rate and its changing trends over a 20-year period in a large referral/teaching institution in Eastern India.
Methods:  A retrospective analysis of maternal deaths was carried out from January 1986 to December 2005 at the Department of Obstetrics and Gynaecology, R. G. Kar Medical College and Hospital, Kolkata, India. Records were divided into four 5-yearly periods: 1986–1990; 1991–1995; 1996–2000; and 2001–2005, for comparison of the trends. The initial interval from 1986 to 1990 was chosen as the reference period.
Results:  The cumulative maternal mortality ratio (MMR) was 599.3 per 100 000 live births. Comparison between the first 5-year period (1986–1991) and the last (2001–2005) showed a statistical significant downward trend in MMR (683.6 vs 474.3; P  < 0.001). Deaths due to direct causes are still the leading cause, accounting for 82.09% of total deaths. Hypertensive disorders (36.14%), hemorrhage (21.91%) and sepsis (19.54%) were still the major causes of direct obstetric deaths throughout the study period. Hypertensive disorders alone showed a substantial decline after the introduction of magnesium sulphate.
Conclusion:  The fall in maternal mortality has been very slow.  相似文献   
17.
18.
Haemophilus influenzae is an important respiratory pathogen. Emergence of resistance to various antibiotics is a major problem in patient management. A total of 90 strains of H. influenzae were characterized from specimens obtained from patients of acute respiratory tract infection; 13 (14.4%) belonged to type beta. On biotyping, 90% strains belonged to biotype II. The frequency of resistance to various antibiotics was as follows: cotrimoxazole 33.3% ampicillin 21.1%, cephalexin 7.8%, chloramphenicol 7.8%, ciprofloxacin 2.5% erythromycin and tetracycline 5% each. All the ampicillin-resistant strains produced beta-lactamase as detected by nitrocefin disc method. None of the strains exhibited resistance to cefaclor and third generation cephalosporins. The present study showed emergence of variable resistance to ampicillin, cotrimoxazole and other antibiotics. It is important for the clinical microbiology laboratory to monitor drug resistant strains for instituting appropriate antibiotic therapy of respiratory infections due to H. influenzae.  相似文献   
19.
Neuropeptides form a part of the brain-gut axis which may regulate gastrointestinal functions, including immune regulation. Various changes in the neuropeptides--most important, vasoactive intestinal peptide and substances P (VIP and SP)--have been described in inflammatory bowel disease. We employed a sensitive immunoperoxidase (avidin-biotin-peroxidase complex) technique, using anti-VIP and anti-SP antibodies to localize and compare the distribution of VIP and SP in the colon. Colon specimens from 19 normal subjects, eight patients with ulcerative colitis (UC), and eight with Crohn's disease (CD) were used. In the normal colon, VIP and SP immunoreactivity (IR) were localized in the muscularis mucosa, circular muscles, walls of blood vessels, nerve fibers, and some distinct cells, probably enterochromaffin cells. SP-IR was also present in the epithelial cells, mainly along the basolateral domain. VIP-IR was considerably diminished at all locations in patients with UC and CD. However, the SP-IR was increased in UC in the colonic epithelial cells along the basolateral areas. The SP-IR was intense in patients with CD, in the epithelium, the granulomas, cells lining the mucosal fissure, and in the muscle layers. In contrast to normals, SP-IR in patients with CD was observed both in the longitudinal and circular muscles. We conclude that VIP-IR and SP-IR are distributed widely in the mucosa, submucosa, and in the circular muscle in normal colon. VIP-IR is decreased in UC and CD, whereas SP-IR is increased in both, but more so in CD.  相似文献   
20.
Allogeneic stem cell transplantation (allo-SCT) after a reduced-intensity conditioning (RIC) protocol is associated with decreased short-term toxicity. This suggests that the procedure could be performed on an outpatient basis. We analysed the incidence and risk factors of grade >or=2 conditioning-related toxicities (CRTs) as a hallmark for hospital admission, in 41 consecutive patients allografted from an HLA identical sibling after RIC. The RIC regimen consisted of fludarabine plus melphalan for lymphoid malignancies, and fludarabine plus busulphan for myeloid malignancies. In all, 11 patients (27%) did not experience any toxicity. The more frequent CRTs observed were neutropenic fever and gastrointestinal toxicity. The median duration of hospitalisation was 27 (range, 17-50) days. If allo-SCT had been planned as an outpatient procedure and admission indicated only in the case of >or=2 CRTs, the inpatient period would have decreased to 9 (range, 0-33) days (P<0.001). No risk factors for CRTs were identified. Allo-SCT after an RIC regimen is a well-tolerated procedure. Our results warrant a prospective pilot trial of nonmyeloablative allo-SCT performed in the outpatient setting.  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