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   1177篇
  免费   64篇
  国内免费   6篇
耳鼻咽喉   11篇
儿科学   32篇
妇产科学   32篇
基础医学   143篇
口腔科学   138篇
临床医学   54篇
内科学   213篇
皮肤病学   19篇
神经病学   121篇
特种医学   26篇
外科学   122篇
综合类   6篇
一般理论   1篇
预防医学   137篇
眼科学   29篇
药学   110篇
中国医学   17篇
肿瘤学   36篇
  2023年   9篇
  2022年   23篇
  2021年   37篇
  2020年   29篇
  2019年   53篇
  2018年   44篇
  2017年   28篇
  2016年   34篇
  2015年   46篇
  2014年   56篇
  2013年   61篇
  2012年   113篇
  2011年   123篇
  2010年   55篇
  2009年   49篇
  2008年   60篇
  2007年   66篇
  2006年   62篇
  2005年   41篇
  2004年   33篇
  2003年   31篇
  2002年   42篇
  2001年   28篇
  2000年   22篇
  1999年   24篇
  1998年   6篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   2篇
  1993年   2篇
  1992年   6篇
  1991年   3篇
  1990年   4篇
  1989年   2篇
  1988年   5篇
  1987年   4篇
  1986年   5篇
  1985年   2篇
  1983年   1篇
  1981年   3篇
  1980年   2篇
  1979年   1篇
  1978年   3篇
  1976年   3篇
  1975年   3篇
  1974年   3篇
  1973年   1篇
  1970年   2篇
  1968年   3篇
排序方式: 共有1247条查询结果,搜索用时 15 毫秒
41.
Background: The aim of this study is to evaluate the periodontal status and the presence of opportunistic oral lesions in human immunodeficiency virus–positive (HIV+) patients under highly active antiretroviral therapy (HAART) and their association with cluster of differentiation (CD)4+ and CD4+ nadir T‐cell counts and viral load levels. Methods: Clinical periodontal parameters and the presence of opportunistic oral lesions along with records of CD4+ counts and viral load levels were evaluated in 29 individuals (16 females; mean age: 42.7 years) with previous serologic diagnosis of HIV, from the acquired immunodeficiency syndrome program of the Health Center of Duque de Caxias, Rio de Janeiro, Brazil. Results: All individuals presented gingivitis or periodontitis. A higher non‐significant prevalence of periodontitis was found in smokers (93.8%) compared with non‐smokers (76.9%). A significant weak positive correlation was observed between CD4+ counts and missing teeth (ρ = 0.380, P <0.05), CD4+ nadir and periodontal diagnosis (ρ = 0.418, P <0.005), and CD4+ nadir and moderate probing depth (PD) (ρ = 0.424, P <0.05). When only non‐smokers were analyzed, a significant moderate positive association was found between viral load and moderate clinical attachment level (CAL) (ρ = 0.638, P <0.05), CD4+ nadir and diagnosis (ρ = 0.586, P <0.05), and CD4+ nadir and moderate CAL (ρ = 0.680, P <0.05). Analysis considering only smokers found no correlations between serologic parameters and demographic or clinical parameters. Conclusions: The current investigation demonstrates that HIV+ individuals under HAART presents a high prevalence of mild to moderate periodontal disease. Viral load levels, CD4+ nadir, and CD4+ counts may present a weak to moderate correlation to the number of missing teeth, periodontal diagnosis, moderate PD, and moderate CAL, which may also reflect some effect of these systemic conditions on the periodontal status.  相似文献   
42.
43.
44.
45.
Fas/Fas ligand (Fas-L) engagement, a potent inducer of apoptosis, is also important for cellular activation, regulation of effector and chemotactic activity, and secretion of chemokines and cytokines. We evaluated the relevance of Fas/Fas-L in the regulation of myocarditis induced by Trypanosoma cruzi infection and observed that in Fas-L(-/-) mice (gld/gld), cardiac infiltration was significantly reduced, accordingly showing less cardiomyocyte destruction. Fluorescence-activated cell sorting analysis of cardiac inflammatory cells showed higher numbers of CD8(+) T cells in BALB/c compared with gld/gld mice but similar levels of lymphocyte function-associated antigen-1, intercellular adhesion molecule, CD2, and CD69 expression; MAC-1(+) myeloid cells and mast cells were increased in BALB/c mice, whereas gld/gld mice exhibited an enrichment of CD4(+/low) T cells. Intracellular labeling of cytokines revealed no clear cardiac skewing of Th1 or Th2 responses, but we found a higher number of interleukin-10(+) cells in gld/gld mice and a deficient expression of vascular cell adhesion molecule-1 on cardiac endothelial cells in gld/gld mice. Finally, we found a population of CD3(+) but CD4/CD8 double negative cardiac T cells in both groups of infected mice, but down-regulation of some adhesion molecules and surface receptors was only observed in gld/gld mice, indicating a targeted T-cell population mostly affected by the lack of Fas-L engagement. These results point to a role for myocarditis regulation by Fas/Fas-L beyond its possible direct relevance in cellular death.  相似文献   
46.
Aedes aegypti transmits the viruses that cause yellow and dengue fevers. Vector control is essential, since a vaccine for dengue has not as yet been made available. This work reports on the larvicidal activity of Myracrodruon urundeuva leaf lectin (MuLL) against A. aegypti fourth-stage larvae (L4). Also, the resistance of MuLL to digestion by L4 gut proteases and the effects of MuLL on protease, trypsin-like and α-amylase activities from L4 gut were evaluated to determine if lectin remains active in A. aegypti gut and if insect enzyme activities can be modulated by MuLL. MuLL promoted mortality of L4 with LC50 of 0.202 mg/ml. Haemagglutinating activity of MuLL was detected even after incubation for 96 h with L4 gut preparation containing protease activity. MuLL affected the activity of gut enzymes, inhibiting protease and trypsin activities and stimulating α-amylase activity. The results suggest that MuLL may become a new biodegradable larvicidal agent for dengue control. Larvicidal activity of MuLL may be linked to its resistance to proteolysis by larval enzymes and interference in the activity of digestive larval enzymes.  相似文献   
47.
Increased thyroid hormone (TH) levels are known to induce cardiac hypertrophy. Some studies have provided evidence for a functional link between angiotensin II (ANG II) and transforming growth factor β1 (TGF-β1) in the heart, both being able to also induce cardiac hypertrophy. However, the contribution of this growth factor activated directly by TH or indirectly by ANG II in cardiac hypertrophy development remains unknown. To analyze the possible role of TGF-β1 in cardiac hypertrophy induced by TH and also to evaluate if the TGF-β1 effect is mediated by ANG II receptors, we employed Wistar rats separated into control, hypothyroid (hypo) and hyperthyroid (T4 − 10) groups combined or not with ANG II receptor blockers (losartan or PD123319). Serum levels of T3 and T4, systolic pressure and heart rate confirmed the thyroid state of the groups. The T4 − 10 group presented a significant increase in cardiac TGF-β1 levels; however, TGF-β1 levels in the hypo group did not change in relation to the control. Inhibition of the increase in cardiac TGF-β1 levels was observed in the groups treated with T4 in association with losartan or PD123319 when compared to the T4 − 10 group. These results demonstrate for the first time the TH-modulated induction of cardiac TGF-β1 in cardiac hypertrophy, and that this effect is mediated by ANG II receptors.  相似文献   
48.
We investigated the myocardial thioredoxin-1 and hydrogen peroxide concentrations and their association with some prosurvival and pro-apoptotic proteins, during the transition from myocardial infarction (MI) to heart failure in rats. Male Wistar rats were divided into the following six groups: three sham-operated groups and three MI groups, each at at 2, 7 and 28 days postsurgery. Cardiac function was analysed by echocardiography; the concentration of H(2)O(2) and the ratio of reduced to oxidized glutathione were measured spectrophotometrically, while the myocardial immunocontent of thioredoxin-1, angiotensin II, angiotensin II type 1 and type 2 receptors, p-JNK/JNK, p-ERK/ERK, p-Akt/Akt, p-mTOR/mTOR and p-GSK3β/GSK3β was evaluated by Western blot. Our results show that thioredoxin-1 appears to make an important contribution to the reduced H(2)O(2) concentration. It was associated with lower JNK expression in the early period post-MI (2 days). However, thioredoxin-1 decreased, while renin-angiotensin system markers and levels of H(2)O(2) increased, over 28 days post-MI, in parallel with some signalling proteins involved in maladaptative cardiac remodelling and ventricular dysfunction. These findings provide insight into the time course profile of endogenous antioxidant adaptation to ischaemic injury, which may be useful for the design of therapeutical strategies targeting oxidative stress post-MI.  相似文献   
49.
BackgroundObsessive–compulsive disorder (OCD) is a chronic condition that normally presents high rates of psychiatric comorbidity. Depression, tic disorders and other anxiety disorders are among the most common comorbidities in OCD adult patients. There is evidence that the higher the number of psychiatric comorbidities, the worse the OCD treatment response. However, little is known about the impact of OCD treatment on the outcome of the psychiatric comorbidities usually present in OCD patients. The aim of this study was to investigate the impact of exclusive, conventional treatments for OCD on the outcome of additional psychiatric disorders of OCD patients, detected at baseline.MethodsSeventy-six patients with primary OCD admitted to the treatment protocols of the Obsessive–Compulsive Spectrum Disorders Program between July 2007 and December 2009 were evaluated at pre-treatment and after 12 months. Data were analyzed to verify possible associations between OCD treatment response and the outcome of psychiatric comorbidities.ResultsResults showed a significant association between OCD treatment response and improvement of major depression and dysthymia (p-value = 0.002), other anxiety disorders (generalized anxiety disorder, social phobia, specific phobia, posttraumatic stress disorder, panic disorder, agoraphobia and anxiety disorder not otherwise specified) (p-value = 0.054) and tic disorders (p-value = 0.043).LimitationsThis is an open, non-blinded study, without rating scales for comorbid conditions. Further research is necessary focusing on the possible mechanisms by which OCD treatment could improve these specific disorders.ConclusionsOur results suggest that certain comorbid disorders may benefit from OCD-targeted treatment.  相似文献   
50.
Skin biopsy samples from 145 relapse leprosy cases and from five different regions in Brazil were submitted for sequence analysis of part of the genes associated with Mycobacterium leprae drug resistance. Single nucleotide polymorphisms (SNPs) in these genes were observed in M. leprae from 4 out of 92 cases with positive amplification (4.3%) and included a case with a mutation in rpoB only, another sample with SNPs in both folP1 and rpoB, and two cases showing mutations in folP1, rpoB, and gyrA, suggesting the existence of multidrug resistance (MDR). The nature of the mutations was as reported in earlier studies, being CCC to CGC in codon 55 in folP (Pro to Arg), while in the case of rpoB, all mutations occurred at codon 531, with two being a transition of TCG to ATG (Ser to Met), one TCG to TTC (Ser to Phe), and one TCG to TTG (Ser to Leu). The two cases with mutations in gyrA changed from GCA to GTA (Ala to Val) in codon 91. The median time from cure to relapse diagnosis was 9.45 years but was significantly shorter in patients with mutations (3.26 years; P = 0.0038). More than 70% of the relapses were multibacillary, including three of the mutation-carrying cases; one MDR relapse patient was paucibacillary.  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