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   646篇
  免费   21篇
  国内免费   4篇
耳鼻咽喉   7篇
儿科学   9篇
妇产科学   23篇
基础医学   77篇
口腔科学   4篇
临床医学   59篇
内科学   77篇
皮肤病学   24篇
神经病学   70篇
特种医学   18篇
外科学   58篇
综合类   2篇
预防医学   72篇
眼科学   14篇
药学   94篇
肿瘤学   63篇
  2023年   3篇
  2022年   4篇
  2021年   5篇
  2020年   7篇
  2019年   11篇
  2018年   11篇
  2017年   11篇
  2016年   12篇
  2015年   7篇
  2014年   17篇
  2013年   45篇
  2012年   32篇
  2011年   33篇
  2010年   28篇
  2009年   17篇
  2008年   40篇
  2007年   38篇
  2006年   49篇
  2005年   24篇
  2004年   49篇
  2003年   37篇
  2002年   44篇
  2001年   12篇
  2000年   6篇
  1999年   12篇
  1998年   13篇
  1997年   4篇
  1996年   8篇
  1995年   8篇
  1994年   7篇
  1993年   8篇
  1992年   6篇
  1991年   4篇
  1990年   6篇
  1989年   7篇
  1988年   5篇
  1987年   2篇
  1986年   6篇
  1985年   6篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1980年   4篇
  1979年   2篇
  1978年   4篇
  1977年   3篇
  1974年   2篇
  1967年   3篇
  1964年   1篇
排序方式: 共有671条查询结果,搜索用时 15 毫秒
11.
Purpose. In order to evaluate the possible antiinflammatory action of bisphosphonates, the effect of the drugs on the secretion of proinflammatory cytokines (IL-l, IL-6 and TNF) from macrophages was studied. Liposomes or high concentration of extracellular calcium was used to enhance the intracellular delivery of bisphosphonates. Methods. RAW 264 cells were used as macrophage model, and they were induced with lipopolysaccharide to produce the cytokines. The cytokine concentrations in the culture supernatants were measured with time-resolved fluoroimmunoassay. Results. As a free drug, clodronate and pamidronate, but not etidronate, inhibited LPS-stimulated secretion of the cytokines from macrophage-like RAW 264 cells. Low concentrations of pamidronate, however, induced the IL-6 secretion, and the cytokine inhibitory action at the higher concentrations of pamidronate was attributed to cytotoxicity of the compound. The cytokine induction or toxic effects were not observed with clodronate or etidronate. When the drugs were encapsulated in negatively charged unilamellar liposomes, the inhibitory potency of both clodronate and etidronate enhanced by a factor of 10-20, while that of pamidronate was not increased. The complex formation of bisphosphonates with extracellular calcium, although enhancing the uptake of the compounds by macrophages, did not considerably increase their cytokine inhibitory potency. Conclusions. Bisphosphonates have inhibitory action on cytokine secretion by macrophages. The non-cytotoxic cytokine inhibition by liposome encapsulated clodronate could be beneficial in local inflammatory diseases, where the inflammation is sustained by the excessive amounts of inflammatory cytokines produced by activated macrophages.  相似文献   
12.
Suhonen  Pekka  Järvinen  Tomi  Rytkönen  Päivi  Peura  Pekka  Urtti  Arto 《Pharmaceutical research》1991,8(12):1539-1542
0,0-(l,4-Xylylene) bispilocarpic acid esters are pilocarpine pro-drugs containing two pilocarpic acid monoesters linked with one pro-moiety. Each mole of prodrug forms two pilocarpine moles in the presence of esterases. Corneal uptake and permeability of various bispilocarpic acid diesters were investigated in vitro using isolated albino rabbit corneas. The permeability coefficient of pilocarpine was 2.8 × 10 –6 cm/sec, whereas for bispilocarpic acid diesters, despite their large molecular weights (between 638 and 722), permeability coefficients were 6.5–20.2 × 10 –6 cm/sec. Only pilocarpine, and no intact prodrug, was observed at the endothelial side. Corneal uptake was increased with increasing lipophilicity, but a parabolic relationship between the logarithm of the apparent partition coefficient (1-octanol–pH 7.4 phosphate buffer) (log PC) and the corneal permeability was noticed. Corneal permeability and the rate of enzymatic hydrolysis of the compounds correlated well. The corneal permeability of pilocarpine given as lipophilic bispilocarpic acid diester (log PC 3) prodrugs seems to be controlled by the formation of pilocarpine in the corneal epithelium rather than by the absorption of prodrugs into the epithelium or their epithelium–stroma transport rate.  相似文献   
13.
Objective To evaluate the use of the pre-operative tumour-associated trypsin inhibitor (TATI) level and residual tumour size at primary surgery as a prognostic indicators for patients with Stage III epithelial ovarian cancer.
Design Retrospective cohort study.
Setting Department of Obstetrics and Gynaecology, University Hospital, Helsinki, Finland.
Participants Ninety-eight women with Stage III ovarian cancer.
Methods TATI was measured by radioimmunoassay from serum samples obtained within one week before surgery. A cutoff value of 22 μg/L was used. Multivariate analysis included pre-operative TATI level, age, histologic grade and histologic type. Mantel-Cox test was used for calculating statistical significance of differences in survival between groups.
Main outcome measures Cumulative five-year survival, pre-operative serum TATI level and residual tumour size.
Results Surgery was optimal (residual tumour size ≤ 2 cm) in 55 patients and suboptimal (residual tumour size > 2 cm) in 43. Pre-operative TATI level ≤ 22 μg/L predicted better prognosis both in patients with optimal and suboptimal surgery compared with patients with pre-operative TATI level > 22 μ/L. Patients with optimal surgery and a pre-operative TATI > 22 μg/L had a twofold relative risk of death compared with those with a pre-operative TATI ≤ 22 μg/L. The cumulative survival was less than three years for patients with suboptimal surgery and pre-operative TATI > 22 μg/L.
Conclusions Pre-operative serum TATI in combination with residual tumour size may be useful in stratifying patients with Stage III ovarian cancer into different categories in randomised treatment trials.  相似文献   
14.
15.
16.
We report on oxygenation changes noninvasively recorded by multichannel continuous-wave near infrared spectroscopy (CW-NIRS) during endovascular neuroradiologic interventions requiring temporary balloon occlusion of arteries supplying the cerebral circulation. Digital subtraction angiography (DSA) provides reference data on the site, timing, and effectiveness of the flow stagnation as well as on the amount and direction of collateral circulation. This setting allows us to relate CW-NIRS findings to brain specific perfusion changes. We focused our analysis on the transition from normal perfusion to vessel occlusion, i.e., before hypoxia becomes clinically apparent. The localization of the maximal response correlated either with the core (occlusion of the middle cerebral artery) or with the watershed areas (occlusion of the internal carotid artery) of the respective vascular territories. In one patient with clinically and angiographically confirmed insufficient collateral flow during carotid artery occlusion, the total hemoglobin concentration became significantly asymmetric, with decreased values in the ipsilateral watershed area and contralaterally increased values. Multichannel CW-NIRS monitoring might serve as an objective and early predictive marker of critical perfusion changes during interventions—to prevent hypoxic damage of the brain. It also might provide valuable human reference data on oxygenation changes as they typically occur during acute stroke.  相似文献   
17.
18.
A 43-year-old female with Staphyloccocus-induced perianal abscess, was admitted to hospital because of a clinical picture of acute renal failure and thrombotic microangiopathy. Schistocytes, thrombopenia, a negative Coombs test and no detectable plasma haptoglobin were diagnostic for thrombotic microangiopathy. Antibiotics, surgical drainage, plasmapheresis and fresh frozen plasma were given with a favourable evolution. We review the prognostic factors determining recovery of renal function and hematological abnormalities.  相似文献   
19.
The effects of acute myocardial infarction on the pharmacokinetics of digoxin were studied. Digoxin, 0.75 mg, was given orally to 12 patients with left-sided cardiac failure due to acute myocardial infarction and to 9 healthy control subjects. Serum concentration of digoxin in the first 4 hours and the area under the serum concentration-time curve in the first 12 hours after administration of the drug were lower in patients with infarction than in control subjects (P less than 0.01). The 24 hour area under the concentration curve, the amount excreted in urine and the renal clearance did not differ between the groups. The 24 hour area under the concentration curve correlated with the predigoxin pulmonary capillary wedge pressure and with heart rate (P less than 0.01). The decrease of renal clearance of digoxin was related to the serum activity of MB isoenzyme of creatine kinase (P less than 0.001). Morphine reduced and delayed the peak serum concentrations of digoxin (P less than 0.001). Thus, the absorption of oral digoxin was slower and the peak concentrations remained lower in patients with acute myocardial infarction than in healthy control subjects. However, the total amount of digoxin absorbed was unchanged.  相似文献   
20.
Inherited predisposition to breast cancer is known to be caused by loss-of-function mutations in BRCA1, BRCA2, PALB2, CHEK2, and other genes involved in DNA repair. However, most families severely affected by breast cancer do not harbor mutations in any of these genes. In Finland, founder mutations have been observed in each of these genes, suggesting that the Finnish population may be an excellent resource for the identification of other such genes. To this end, we carried out exome sequencing of constitutional genomic DNA from 24 breast cancer patients from 11 Finnish breast cancer families. From all rare damaging variants, 22 variants in 21 DNA repair genes were genotyped in 3,166 breast cancer patients, 569 ovarian cancer patients, and 2,090 controls, all from the Helsinki or Tampere regions of Finland. In Fanconi anemia complementation gene M (FANCM), nonsense mutation c.5101C>T (p.Q1701X) was significantly more frequent among breast cancer patients than among controls [odds ratio (OR) = 1.86, 95% CI = 1.26–2.75; P = 0.0018], with particular enrichment among patients with triple-negative breast cancer (TNBC; OR = 3.56, 95% CI = 1.81–6.98, P = 0.0002). In the Helsinki and Tampere regions, respectively, carrier frequencies of FANCM p.Q1701X were 2.9% and 4.0% of breast cancer patients, 5.6% and 6.6% of TNBC patients, 2.2% of ovarian cancer patients (from Helsinki), and 1.4% and 2.5% of controls. These findings identify FANCM as a breast cancer susceptibility gene, mutations in which confer a particularly strong predisposition for TNBC.Breast cancer is the most common cancer affecting women worldwide. It is also the principal cause of death from cancer among women globally, accounting for 14% of all cancer deaths (1). The etiology of breast cancer is multifactorial, and the risk depends on various factors like age, family history, and reproductive, hormonal, or dietary factors. The majority of breast cancers are sporadic, but approximately 15% of cases show familial aggregation (2, 3). Since the identification of the first breast and ovarian cancer susceptibility genes breast cancer 1 and 2 (BRCA1 and BRCA2, respectively) by linkage analysis and positional cloning, several breast cancer susceptibility genes and alleles with different levels of risk and prevalence in the population have been recognized. BRCA1 and BRCA2 mutation carriers have more than 10-fold increased risk of breast cancer compared with women in the general population, and mutations in TP53, PTEN, STK11, and CDH1 have also been associated with a high lifetime risk of breast cancer in the context of rare inherited cancer syndromes (4). In addition, rare variants in genes such as checkpoint kinase 2 (CHEK2), ataxia telangiectasia mutated (ATM), and BRCA1 interacting helicase BRIP1, that confer a two- to fourfold increased risk, and in partner and localizer of BRCA2 (PALB2), with even higher risk estimates, have been found with candidate gene approaches (5, 6), and an increasing number of common low-risk loci with modest odds ratios (ORs; as much as 1.26-fold increased risk for heterozygous carriers) have been identified by genome-wide association studies (7).However, the major portion of hereditary breast cancer still remains unexplained, and many susceptibility loci are yet to be found. Exome sequencing combined with genotyping of the identified variants in case-control analysis is an effective method to recognize novel risk alleles, based on the assumption that disease-causing variants are rare and often accumulate in the protein-coding areas of the genome (810).Since the discovery that proteins encoded by the BRCA1 and BRCA2 breast/ovarian cancer susceptibility genes are directly involved in homologous recombination repair of DNA double-strand breaks, it has been evident that other genes involved in DNA repair are attractive breast cancer susceptibility candidates (4). Biallelic mutations in ATM gene cause rare ataxia telangiectasia disease and are associated with an increased risk for breast cancer as a result of improper DNA damage response (11). Fanconi anemia (FA) is a rare genetic disorder caused by biallelic mutations in FA genes that also participate in DNA repair. At least 15 FA genes have been identified (12). Patients with heterozygous mutations in certain FA genes have an elevated risk for various cancers, and monoallelic mutations in at least four of these genes [BRCA2, BRIP1, PALB2, and RAD51 paralog C (RAD51C)] are associated with an increased risk of breast or ovarian cancer (12, 13). Recurrent founder mutations in several cancer susceptibility genes, including the BRCA2, PALB2, and RAD51C FA genes, have been identified in the Finnish population (1416). The PALB2 and RAD51C founder mutations have been detected at 2% frequency in Finnish breast or ovarian cancer families (1517), whereas, in other populations, mutations in these genes are rare and often unique for each family. Founder effects in the isolated populations such as Finland or Iceland may enrich certain mutations and thus explain a significant proportion of all mutations in certain genes (18, 19). This provides an advantage in the search for novel susceptibility genes and alleles.In this study, we used exome sequencing to uncover previously unidentified recurrent breast or ovarian cancer predisposing variants in the Finnish population with a focus on DNA repair genes. Selected variants were further genotyped in a large case-control sample set. Our investigation revealed an association of a nonsense mutation (rs147021911) in an FA complementation gene, FANCM, with breast cancer, especially with triple-negative (TN) breast cancer (TNBC).  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