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   10412篇
  免费   644篇
  国内免费   34篇
耳鼻咽喉   125篇
儿科学   251篇
妇产科学   265篇
基础医学   1479篇
口腔科学   169篇
临床医学   961篇
内科学   2473篇
皮肤病学   219篇
神经病学   951篇
特种医学   239篇
外科学   1239篇
综合类   161篇
一般理论   12篇
预防医学   723篇
眼科学   251篇
药学   901篇
中国医学   27篇
肿瘤学   644篇
  2023年   52篇
  2022年   102篇
  2021年   243篇
  2020年   114篇
  2019年   154篇
  2018年   211篇
  2017年   164篇
  2016年   202篇
  2015年   237篇
  2014年   301篇
  2013年   425篇
  2012年   620篇
  2011年   636篇
  2010年   310篇
  2009年   344篇
  2008年   570篇
  2007年   608篇
  2006年   559篇
  2005年   563篇
  2004年   563篇
  2003年   495篇
  2002年   505篇
  2001年   223篇
  2000年   190篇
  1999年   166篇
  1998年   97篇
  1997年   80篇
  1996年   74篇
  1995年   65篇
  1994年   71篇
  1993年   77篇
  1992年   141篇
  1991年   146篇
  1990年   113篇
  1989年   132篇
  1988年   122篇
  1987年   110篇
  1986年   114篇
  1985年   78篇
  1984年   86篇
  1983年   72篇
  1982年   74篇
  1981年   56篇
  1980年   53篇
  1979年   50篇
  1978年   48篇
  1977年   45篇
  1976年   43篇
  1975年   63篇
  1971年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
BACKGROUND. The identification and treatment of individuals with tuberculosis (TB) is a global public health priority. Accurate diagnosis of pulmonary active TB (ATB) disease remains challenging and relies on extensive medical evaluation and detection of Mycobacterium tuberculosis (Mtb) in the patient’s sputum. Further, the response to treatment is monitored by sputum culture conversion, which takes several weeks for results. Here, we sought to identify blood-based host biomarkers associated with ATB and hypothesized that immune activation markers on Mtb-specific CD4+ T cells would be associated with Mtb load in vivo and could thus provide a gauge of Mtb infection.METHODS. Using polychromatic flow cytometry, we evaluated the expression of immune activation markers on Mtb-specific CD4+ T cells from individuals with asymptomatic latent Mtb infection (LTBI) and ATB as well as from ATB patients undergoing anti-TB treatment.RESULTS. Frequencies of Mtb-specific IFN-γ+CD4+ T cells that expressed immune activation markers CD38 and HLA-DR as well as intracellular proliferation marker Ki-67 were substantially higher in subjects with ATB compared with those with LTBI. These markers accurately classified ATB and LTBI status, with cutoff values of 18%, 60%, and 5% for CD38+IFN-γ+, HLA-DR+IFN-γ+, and Ki-67+IFN-γ+, respectively, with 100% specificity and greater than 96% sensitivity. These markers also distinguished individuals with untreated ATB from those who had successfully completed anti-TB treatment and correlated with decreasing mycobacterial loads during treatment.CONCLUSION. We have identified host blood-based biomarkers on Mtb-specific CD4+ T cells that discriminate between ATB and LTBI and provide a set of tools for monitoring treatment response and cure.TRIAL REGISTRATION. Registration is not required for observational studies.FUNDING. This study was funded by Emory University, the NIH, and the Yerkes National Primate Center.  相似文献   
4.
5.
6.
7.
Nutcracker fracture of the cuboid is a rare injury usually caused by forced abduction of the forefoot on a fixed hindfoot. We report a case of this fracture in a 58-year-old man who was treated on the principle of ligamentotaxis and the position being held with Kirchner wires for a period of 5 weeks. He recovered without any complications and with good ankle and subtalar movements. At 5 months following the injury he had returned to his previous occupation. We think this novel way of treating this rare fracture is simple and gave a good result in this patient.  相似文献   
8.
Case report A 28-year-old female patient was admitted because of painlessmacroscopic haematuria. Past history included severe mentalretardation and nystagmus. At age 17, a computed tomography(CT) scan of the brain showed an absent cerebellar vermis andcerebellar hypoplasia. There was no  相似文献   
9.
Vinylogous (Groups III and V ) and acetylenologous (Group IV ) analogs of the classical β-adrenergic agents — stimulants and blockers — were prepared in order to evaluate the effect of degree of saturation, position of unsaturation and rigidity of the chain linking the aromatic ring and the amino containing functional group on biological activity. Derivatives from Group III , which represent 4-aryl-3-butenyl-2-ol-amine analogs of Group II , retained β1-adrenoceptor antagonist activity albeit substantially less potent (50–200-fold) than that possessed by their aryloxy counterparts. Consistent with the SAR for Group II compounds, substitution at position 2 of the aromatic ring yielded the most potent antagonists ( 5a, 5d, 5g ), with KB's ranging from 73–93 nM while 3,4-dichloro substitution ( 5e ) markedly reduced antagonist potency (KB = 2,400 nM). Agonist activity was also noted for 5b and 5d , suggesting that these compounds may be best classified as partial agonists. Representatives from Groups IV and V were inactive as antagonists at the β1-adrenoceptor confirming the importance of the spatial relationship between the hydroxyl and the amino nitrogen.  相似文献   
10.
Cytochrome P450-dependent arachidonic acid metabolism in human kidney   总被引:2,自引:0,他引:2  
Cytochrome P450-dependent arachidonic acid metabolism in human kidney cortex from several postmortem subjects has been characterized. Using HPLC and GC/MS, four cytochrome P450-arachidonic acid metabolites were tentatively but not unequivocally identified as epoxyeicosatrienoic acid (EET), dihydroxyeicosatrienoic acid (DHT) and 19- and 20-hydroxyeicosatetraenoic acids, suggesting the involvement of two major cytochrome P450 enzymes, epoxygenase and omega/omega-1 hydroxylases. This pattern of metabolism was similar to that found in rabbit and rat kidneys. The formation of these metabolites was dependent on the presence of NADPH and inhibited by IgG of NADPH-cytochrome P450 (c) reductase. Immunologic studies of renal cytochrome P450 epoxygenase demonstrated that antibodies prepared against human-purified hepatic cytochrome P450 epoxygenase recognized renal enzyme protein and inhibited the enzyme activity by 92%. In contrast, control immunoglobulin did not inhibit renal cytochrome P450 epoxygenase. Antibody inhibition of renal cytochrome P450 epoxygenase demonstrated a degree of conservation of both enzyme proteins between liver and kidney. Antibodies against lauric acid omega/omega-1 hydroxylases (P450 omega) inhibited the formation of omega/omega-1 hydroxylase products, 19- and 20-HETEs. Identical qualitative patterns of arachidonic acid metabolites were observed in all cortical microsomes studied. Interindividual variations were observed in the cytochrome P450-dependent arachidonic acid metabolism, and the activities ranged from 0.031 to 5.027 nmol arachidonic acid converted/mg protein/30 min. which is about a 150-fold difference. However, when the specific activities for total cytochrome P450-dependent arachidonic acid metabolism were calculated, two separate groups could be distinguished, high and low metabolizers of arachidonic acid.(ABSTRACT TRUNCATED AT 250 WORDS)  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