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   6454篇
  免费   493篇
  国内免费   6篇
耳鼻咽喉   39篇
儿科学   214篇
妇产科学   146篇
基础医学   640篇
口腔科学   122篇
临床医学   1007篇
内科学   1233篇
皮肤病学   41篇
神经病学   724篇
特种医学   431篇
外国民族医学   1篇
外科学   647篇
综合类   139篇
预防医学   559篇
眼科学   115篇
药学   477篇
中国医学   9篇
肿瘤学   409篇
  2023年   42篇
  2022年   59篇
  2021年   168篇
  2020年   92篇
  2019年   157篇
  2018年   158篇
  2017年   123篇
  2016年   121篇
  2015年   129篇
  2014年   203篇
  2013年   290篇
  2012年   377篇
  2011年   434篇
  2010年   212篇
  2009年   190篇
  2008年   323篇
  2007年   354篇
  2006年   349篇
  2005年   282篇
  2004年   289篇
  2003年   255篇
  2002年   247篇
  2001年   172篇
  2000年   152篇
  1999年   117篇
  1998年   60篇
  1997年   41篇
  1996年   54篇
  1995年   51篇
  1994年   54篇
  1993年   29篇
  1992年   97篇
  1991年   106篇
  1990年   106篇
  1989年   104篇
  1988年   84篇
  1987年   71篇
  1986年   92篇
  1985年   84篇
  1984年   64篇
  1983年   46篇
  1982年   38篇
  1980年   31篇
  1979年   49篇
  1978年   39篇
  1977年   29篇
  1976年   38篇
  1975年   28篇
  1974年   29篇
  1972年   28篇
排序方式: 共有6953条查询结果,搜索用时 15 毫秒
41.
Acute renal insufficiency is known to occur in patients who are taking ciprofloxacin, particularly the elderly. We report two young patients with cystic fibrosis who presented with acute renal insufficiency after 2-3 weeks of oral ciprofloxacin therapy. The incidence of this adverse effect in children and young adults who have cystic fibrosis is unknown. Multiple mechanisms for ciprofloxacin-induced nephrotoxicity have been proposed.  相似文献   
42.
Recurrence of posterior uveal melanoma after 60Co episcleral plaque therapy   总被引:3,自引:0,他引:3  
The authors analyzed the clinical and follow-up data on 277 selected patients with primary choroidal or ciliochoroidal melanoma who were treated with 60Co plaque radiotherapy between 1976 and 1982. Local recurrence of the irradiated melanoma developed in 39 (14%) patients during the follow-up interval. The 5-year tumor recurrence rate (Kaplan-Meier) was estimated to be 12%. Multivariate prognostic factor analysis (Cox proportional hazards modeling) identified the largest linear tumor dimension and proximity of the posterior margin of the tumor to the optic nerve head as predictors of recurrence. The 5-year survival rate of patients whose tumors recurred (58%) was significantly (log-rank test P = 0.0023) worse than that of patients whose tumor remained clinically controlled (82%).  相似文献   
43.
The relationship between alcoholism and anxiety disorders is complex and has been the subject of much investigation. While data from community samples as well as samples of treatment-seeking populations indicate that these disorders co-occur far more commonly than would be expected by chance, the nature of the relationship is unclear. It is clear from both prevalence as well as order of onset data that various anxiety disorders have differing associations with alcohol problems. There is much overlap in symptomatology of panic disorder, generalized anxiety disorder, and alcohol withdrawal. This observation has led to speculation about common neurochemical perturbations and a kindling phenomenon as a possible connection between these disorders. Cognitive theories have been used to connect alcohol abuse and phobic disorders. Treatment of patients with co-morbid anxiety and alcoholism is discussed.  相似文献   
44.
A model system of a paramagnetic lymphotropic MR contrast agent (Gd-DTPA labeled polyglucose associated macrocomplex, PGM) for T1-weighted MR imaging of lymph nodes in rats and rabbits was evaluated. Pharmacokinetic (tissue accumulation) and MR imaging data (optimal dose and timing parameters) were obtained in normal rats (n = 88) after subcutaneous (SC) injection of paramagnetic, radiolabeled [111In]Gd-DTPA-PGM. A rabbit model of lymph node metastases (n = 8) was ultimately used to demonstrate the potential of MR imaging with Gd-DTPA-PGM for nodal tumor detection. Maximum concentrations of Gd-DTPA-PGM were found in popliteal and paraaortic lymph nodes within 24 h after SC administration, and highest lymph node SNR values were obtained by MR imaging at this time point. The optimum imaging dose was 6–12 μmol Gd/kg. Tumor-lymph node contrast increased from 0.0 ± 1.2 precontrast to 19.2 ± 6.5 (spoiled gradient echo sequence, TR 50/TE 7/flip angle 60°) postcontrast and conspicuity of nodal metastases was improved. Gd-DTPA-PGM accumulates in lymph nodes after SC administration and significantly enhances lymph node signal intensity of normal animals but not metastatic lymph nodes.  相似文献   
45.
The thyroid axis and desipramine treatment in depression   总被引:3,自引:0,他引:3  
Although there has been much recent investigation of the role of thyroid function in affective illness, few studies have addressed the effects of the tricyclic antidepressants on the pituitary-thyroid axis. In the present study, thyroid functions (TFTs) and thyrotropin-releasing hormone (TRH) stimulation of thyroid-stimulating hormone (TSH) were measured before and after treatment with desipramine (DMI) in 13 men with a diagnosis of major depressive disorder. All subjects had normal TFTs and baseline TSH measured in a drug-free state at the initiation of the study. Both mean free thyroxine index and baseline TSH decreased after DMI treatment. The amount of decrease in baseline TSH correlated with increase in delta TSH. Four subjects had blunted delta TSH (delta TSH less than or equal to 5 microIU/ml); three of these subjects "normalized" with treatment (delta TSH less than or equal to 5 microIU/ml; greater than or equal to 20 microIU/ml). Two subjects had a high delta TSH, and both "normalized" during treatment. The decrease in both free T4 index and TSH suggests a down-regulation of the thyroid axis at the hypothalamic level. "Normalization" of subtle dysregulation of the thyroid axis is suggested as a mechanism of antidepressant therapy in the treatment of some depressions.  相似文献   
46.
A PCR was developed for the detection of Escherichia coli O157 based on the rfbE O-antigen synthesis genes. A 479-bp PCR product was amplified specifically from E. coli O157 in cell lysates containing 200 or 2 CFU following crude DNA extraction. The PCR detected <1 CFU of E. coli O157 per ml in raw milk following enrichment.  相似文献   
47.
The adhesin P1 of Streptococcus mutans has been studied as an anticaries vaccine antigen. An anti-P1 monoclonal antibody (MAb) bound to S. mutans prior to mucosal immunization of mice was shown previously to alter the amount, specificity, isotype, and biological activity of anti-P1 antibodies. The present study was undertaken to screen this and four additional anti-P1 MAbs for immunomodulatory activity when complexed with S. mutans and administered by a systemic route and to evaluate sera from immunized mice for the ability to inhibit adherence of S. mutans to immobilized human salivary agglutinin. All five MAbs tested influenced murine anti-P1 serum antibody responses in terms of subclass distribution and/or specificity. The effects varied depending on which MAb was used and its coating concentration. Two MAbs promoted a more effective, and two others a less effective, adherence inhibition response. An inverse relationship was observed between the ability of the MAbs themselves to inhibit adherence and the ability of antibodies elicited following immunization with immune complexes to inhibit adherence. Statistically significant correlations were demonstrated between the levels of anti-P1 serum immunoglobulin G2a (IgG2a) and IgG2b, but not of IgG1 or IgG3, and the ability of sera from immunized animals to inhibit bacterial adherence. These results indicate that multiple anti-P1 MAbs can mediate changes in the immune response and that certain alterations are potentially more biologically relevant than others. Immunomodulation by anti-P1 MAbs represents a useful strategy to improve the beneficial immune response against S. mutans.  相似文献   
48.
Streptococcus mutans is considered to be the major etiologic agent of human dental caries. Attachment of S. mutans to the tooth surface is required for the development of caries and is mediated, in part, by the 185-kDa surface protein variously known as antigen I/II, PAc, and P1. Such proteins are expressed by nearly all species of oral streptococci. Characteristics of P1 include an alanine-rich repeat region and a centrally located proline-rich repeat region. The proline-rich region of P1 has been shown to be important for the translational stability and translocation of P1 through the bacterial membrane. We show here that (i) several anti-P1 monoclonal antibodies require the simultaneous presence of the alanine-rich and proline-rich regions for binding, (ii) the proline-rich region of P1 interacts with the alanine-rich region, (iii) like the proline-rich region, the alanine-rich region is required for the stability and translocation of P1, (iv) both the proline-rich and alanine-rich regions are required for secretion of P1 in Escherichia coli, and (v) in E. coli, P1 is secreted in the absence of SecB.  相似文献   
49.
Prior reports suggest an ambivalence regarding treatment in individuals with Post-Traumatic Stress Disorder (PTSD). A model that accommodates such ambivalence is the Transtheoretical Model of Behavior Change (TTM, also known as the Stages-of-Change Model). Fifty veterans presenting for treatment completed self-report measures (94% response rate) that assessed disorder variables and constructs relating to the TTM. While the relationships between the components of each specific construct were found to be consistent with the findings of other studies and a number of predicted relationships between variables were confirmed, many results were inconsistent with the TTM. Notwithstanding questions about the suitability of the self-report measures, the unique characteristics of the veteran sample and the small sample size, the results suggest that the assumptions of the TTM were not met in veterans with PTSD. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
50.
The characterization of a novel Mycobacterium sp. isolated from granulomatous skin lesions of moray eels is reported. Analysis of the hsp65 gene, small-subunit rRNA gene, rRNA spacer region, and phenotypic characteristics demonstrate that this organism is distinct from its closest genetic match, Mycobacterium triplex, and it has been named M. montefiorense sp. nov.  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