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   1236篇
  免费   57篇
  国内免费   1篇
耳鼻咽喉   6篇
儿科学   59篇
妇产科学   33篇
基础医学   158篇
口腔科学   23篇
临床医学   113篇
内科学   320篇
皮肤病学   35篇
神经病学   120篇
特种医学   19篇
外科学   106篇
综合类   2篇
预防医学   77篇
眼科学   17篇
药学   93篇
中国医学   3篇
肿瘤学   110篇
  2023年   5篇
  2022年   16篇
  2021年   35篇
  2020年   25篇
  2019年   28篇
  2018年   42篇
  2017年   24篇
  2016年   30篇
  2015年   25篇
  2014年   45篇
  2013年   43篇
  2012年   85篇
  2011年   71篇
  2010年   43篇
  2009年   46篇
  2008年   94篇
  2007年   104篇
  2006年   73篇
  2005年   71篇
  2004年   65篇
  2003年   58篇
  2002年   54篇
  2001年   25篇
  2000年   28篇
  1999年   24篇
  1998年   14篇
  1997年   13篇
  1996年   7篇
  1995年   10篇
  1994年   6篇
  1993年   3篇
  1992年   12篇
  1991年   11篇
  1990年   17篇
  1989年   5篇
  1988年   11篇
  1987年   4篇
  1986年   3篇
  1985年   9篇
  1984年   2篇
  1983年   2篇
  1981年   2篇
  1979年   1篇
  1974年   1篇
  1972年   1篇
  1941年   1篇
排序方式: 共有1294条查询结果,搜索用时 328 毫秒
1.
The new diagnostic criteria of coeliac disease (CD) give more importance to serological markers. Immunoglobulin A antiendomysial antibodies (IgA-EmA) were determined in 138 sera from 79 coeliac children and the antibody levels compared to IgG and IgA antigliadin antibodies (IgG-AGA, IgA-AGA) in the sera. The assessment was also carried out in 29 children with other gastrointestinal diseases, 29 with non-gastrointestinal diseases and 35 healthy children. The IgA-EmA had a 91.4% specificity and a 88.4% sensitivity for active CD. The corresponding figures were 89.8% and 64.4% for IgA-AGA and 73.7% and 86.2% for IgG-AGA, respectively. The results of IgA-EmA determinations were concordant with the intestinal biopsy findings in 90% of cases, versus 80% for IgA-AGA and 83% for IgG-AGA. In most of the discordant cases the biopsy showed only minor changes, making the classification difficult. All patients with positive IgA2-EmA also had positive IgA1 EmA antibodies. IgA-EmA are an excellent serological marker of CD activity in children and they are useful to decrease the number of intestinal biopsies which are needed to confirm the diagnosis in coeliac patients.  相似文献   
2.
Clonidine tablets have been used in the past for treatment of spasticity with some success. The use of clonidine, however, has been limited by adverse effects, mainly hypotension. Over a two-year period, 17 patients were started on clonidine transdermal delivery system. They were followed for up to 18 months. Twelve of the 17 patients had a beneficial response and have continued on the patch. In ten of these 12 patients, other antispasticity drugs were either reduced or discontinued. In another three of the 17 patients, the response was good, but the patch was discontinued. No patient demonstrated persistent problematic hypotension. Clonidine Transdermal Patch appears to be an effective treatment for spasticity after a spinal cord injury. Adverse effects appear to be minimized using this mode of delivery.  相似文献   
3.
4.
Hemobilia.   总被引:1,自引:0,他引:1  
  相似文献   
5.
A nitrogen-specific gas-chromatographic method is described for the quantitative analysis of soluphylline without the need for derivatization or evaporation of solvent, and using only 50 microliters of serum. The analysis is performed isothermally on a silicone stationary phase, 2% SP 2250 DA (Supelco). After a single neutral extraction with ethyl acetate containing the internal standard (beta-hydroxypropyl theophylline), an aliquot of the organic solvent is injected directly into the gas chromatograph. The detector sensitivity (least measurable amount) for soluphylline was 1 ng.  相似文献   
6.
The PGMY L1 consensus primer pair combined with the line blot assay allows the detection of 27 genital human papillomavirus (HPV) genotypes. We conducted an intralaboratory and interlaboratory agreement study to assess the accuracy and reproducibility of PCR for HPV DNA detection and typing using the PGMY primers and typing amplicons with the line blot (PGMY-LB) assay. A test panel of 109 samples consisting of 29 HPV-negative (10 buffer controls and 19 genital samples) and 80 HPV-positive samples (60 genital samples and 20 controls with small or large amounts of HPV DNA plasmids) were tested blindly in triplicate by three laboratories. Intralaboratory agreement ranged from 86 to 98% for HPV DNA detection. PGMY-LB assay results for samples with a low copy number of HPV DNA were less reproducible. The rate of intralaboratory agreement excluding negative results for HPV typing ranged from 78 to 96%. Interlaboratory reliability for HPV DNA positivity and HPV typing was very good, with levels of agreement of >95% and kappa values of >0.87. Again, low-copy-number samples were more prone to generating discrepant results. The accuracy varied from 91 to 100% for HPV DNA positivity and from 90 to 100% for HPV typing. HPV testing can thus be accomplished reliably with PCR by using a standardized written protocol and quality-controlled reagents. The use of validated HPV DNA detection and typing assays demonstrating excellent interlaboratory agreement will allow investigators to better compare results between epidemiological studies.  相似文献   
7.
Earlier studies showed that mice primed for a few hours with the trans-sialidase (TS) of Trypanosoma cruzi, the agent of Chagas' disease, become highly susceptible to trypanosomal infection. These studies suggest that TS affects parasite virulence independent of antigenic stimulation. Potentially, TS could enhance or reduce the virulence of heterologous microbes depending on the mechanism of TS action and on the type of immune response elicited by the particular parasite. We tested this hypothesis by expressing heterologous TS in Leishmania major, a protozoan parasite that causes cutaneous leishmaniasis and lacks TS and the TS product alpha2-3-linked sialic acid. Leishmania cells transfected with a T. cruzi TS expression construct made high levels of active enzyme, which was present in the promastigotes and shed into the extracellular milieu. TS expression did not affect L. major binding to and entry into cultured macrophages or its tropism for macrophage infection in vivo. However, TS-expressing L. major exhibited elevated virulence in BALB/c mice, as determined by lesion progression, parasite numbers, and macro- and microscopic examination of cutaneous lesions. Several genetic tests proved that the enhanced virulence was directly attributable to TS expression. The results are consistent with TS functioning to sabotage the mouse immune system to confer a growth advantage on T. cruzi and transgenic L. major. These data suggest that heterologous expression of T. cruzi virulence factors in Leishmania may provide a new approach for dissecting their function in vivo.  相似文献   
8.
9.
Vasoactive intestinal peptide (VIP), a neuropeptide that is produced by lymphoid as well as neural cells, exerts a wide spectrum of immunological functions, controlling the homeostasis of the immune system through different receptors expressed in various immunocompetent cells. In the last decade, VIP has been clearly identified as a potent anti-inflammatory factor, which acts by regulating the production of both anti- and pro-inflammatory mediators. In this sense, VIP has been described to prevent death by septic shock, an acute inflammatory disease with a high mortality. In addition, VIP regulates the expression of co-stimulatory molecules, this being an action that may be related to modulating the shift toward Th1 and Th2 differentiation. We have recently reported that VIP prevents the deleterious effects of an experimental model of rheumatoid arthritis, by downregulating both inflammatory and autoimmune components of the disease. Therefore, VIP has been proposed as a promising candidate alternative treatment for acute and chronic inflammatory and autoimmune diseases such as septic shock, arthritis, multiple sclerosis, Crohn disease, or autoimmune diabetes.  相似文献   
10.
Choline acetyltransferase (ChAt) is extensively distributed throughout the CNS where, by catalyzing acetylcholine synthesis, it participates in modulating wide-ranging cholinergic-dependent functions including cognitive performance, sleep, arousal, movement, and visual information processing. Recently, compelling evidence has mounted implicating ChAt in schizophrenia. In particular, studies have identified significant reductions in ChAt activity in the nucleus accumbens and pontine tegmentum of such patients, which furthermore correlate significantly with measures of cognitive performance in the disorder. Similarly, elevated levels of choline, the acetylcholine precursor, have been identified among patients, implicating altered ChAt activity in these individuals. We sought to investigate the potential contribution of three ChAt gene polymorphisms in schizophrenia, and uncovered evidence for significant association between one of these, rs1880676G/A, and disease susceptibility among Basque individuals (genotypewise chi(2) = 20.7, P = 0.00003; allelewise chi(2) = 10.1, P = 0.002). A similar trend for association with susceptibility was observed for a second SNP, rs3810950G/A, (genotypwise chi(2) = 6.4, P = 0.05; allelewise chi(2) = 3.75, P = 0.05). Evidence was also uncovered for a potential influence of these polymorphisms on olanzapine treatment outcome among Spanish patients (F-statistic = 5.02, P = 0.03; F-statistic = 6.53, P = 0.02 respectively), and on improvements in positive symptoms in the case of rs3810950 (F-statistic = 5.3, P = 0.03) and general psychopathology in the case of rs1880676 and rs3810950 (F-statistic = 5.24, P = 0.03; F-statistic = 5.31, P = 0.03 respectively) during therapy. While more comprehensive studies are warranted to determine the precise contribution of ChAt mediated mechanisms in schizophrenia, our findings tentatively implicate a genetic influence of ChAt in the disorder's susceptibility and treatment.  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