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   24953篇
  免费   1643篇
  国内免费   67篇
耳鼻咽喉   300篇
儿科学   621篇
妇产科学   649篇
基础医学   3238篇
口腔科学   1300篇
临床医学   1826篇
内科学   5637篇
皮肤病学   730篇
神经病学   2137篇
特种医学   502篇
外国民族医学   1篇
外科学   2960篇
综合类   156篇
一般理论   6篇
预防医学   2414篇
眼科学   495篇
药学   2137篇
中国医学   171篇
肿瘤学   1383篇
  2023年   173篇
  2022年   449篇
  2021年   815篇
  2020年   504篇
  2019年   720篇
  2018年   873篇
  2017年   627篇
  2016年   649篇
  2015年   749篇
  2014年   958篇
  2013年   1232篇
  2012年   1799篇
  2011年   1827篇
  2010年   1068篇
  2009年   899篇
  2008年   1463篇
  2007年   1372篇
  2006年   1244篇
  2005年   1208篇
  2004年   1073篇
  2003年   983篇
  2002年   893篇
  2001年   563篇
  2000年   539篇
  1999年   438篇
  1998年   180篇
  1997年   154篇
  1996年   150篇
  1995年   119篇
  1994年   88篇
  1993年   89篇
  1992年   290篇
  1991年   265篇
  1990年   242篇
  1989年   179篇
  1988年   181篇
  1987年   148篇
  1986年   161篇
  1985年   124篇
  1984年   94篇
  1983年   82篇
  1982年   66篇
  1980年   54篇
  1979年   110篇
  1978年   54篇
  1977年   59篇
  1975年   59篇
  1974年   66篇
  1973年   63篇
  1971年   58篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
More than 10 million radiologic examinations requiring intravascular injection of iodinated contrast media are performed in the United States each year. Iodinated contrast media are considered to be safe diagnostic drugs, and the incidence of adverse reaction is low. However, as with any drug, the administration of contrast media is not without risk. Nurses involved in patient care should have some understanding of the properties and potential effects of iodinated contrast media.  相似文献   
22.
Neutrophil oxidative metabolism, C3d and beta 2 microglobulin levels, were assessed in nine consecutive patients undergoing cardiopulmonary bypass surgery with polypropylene hollow fiber oxygenators for open cardiac operations. Generation of oxygen free radicals by neutrophils was measured as luminol-enhanced chemiluminescence after stimulation with opsonized Zymosan and phorbol myristate acetate. A significant increase in light emission was detected by using both of the chemiluminescence stimulators. Moreover, a remarkable and significant increase in C3d levels was found already at 10 min. Conversely minimal changes in levels of beta 2 microglobulin were detected during cardiopulmonary bypass surgery. These data suggest that the impact of the patient blood with the foreign surface of cardiopulmonary bypass results in activation of phagocyte cells with increased potential in oxygen consumption. These effects could be partially complement-mediated.  相似文献   
23.
A sample of 400 Lebanese-born women who gave birth at Auburn District Hospital in 1987-1988 was compared with a sample of 400 Australian-born women who gave birth in the same time period. The Lebanese-born women were found to be older and of higher parity than were their Australian-born counterparts; and to have booked their hospital admission significantly later in pregnancy than did the Australian-born women. Lebanese-born women also had frequently made a consanguineous marriage. Certain antenatal and intrapartum complications were more common in the Lebanese-born women, and perinatal mortality and morbidity rates were higher among their infants. The particular problems of pregnancy in Lebanese-born women, and possible ways of overcoming these, are discussed.  相似文献   
24.
Diazepam binding inhibitor (DBI) is a neuropeptide of 11 kDa molecular size and is unevenly distributed in human and rat brain. It appears to function as a negative allosteric modulator of GABAA receptors. In the present paper, using antibodies directed against several synthetic peptides, which correspond to selective regions of human DBI (DBI 51-70, DBI 37-50, DBI 81-101), it is shown that DBI is processed into at least 6 peptide fragments in both postmortem human brain and in cerebrospinal fluid (CSF). One of these fragments was identified as the synthetic DBI 51-70 fragment (an eikosaneuropeptide, ENP) by combined chromatographic procedures. Immunoblotting analysis of the other fragments, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE), revealed an apparent molecular size, ranging from 3-4 kDa for four of them and a larger molecular form of 8 kDa. On the basis of the immunological properties, a tentative amino acid sequence was deduced.  相似文献   
25.
A study of some antiparasitic properties of several homoallylamines and related tetrahydroquinolines and quinolines, previously described, was carried out using in vitro activity assays against the epimastigote form of Trypanosoma cruzi and against Trichomonas vaginalis. Unspecific cytotoxicity against murine macrophages was also studied. Although the antichagasic and trichomonacidal activities are not comparable to those of the standard drugs, nifurtimox and metronidazole, some of the compounds exhibit an interesting specific antiparasitic activity.  相似文献   
26.
The anatomic response to intravitreal bevacizumab injection in three patients with aggressive, posterior retinopathy of prematurity is described. In all cases, the worse eye was treated with a single intravitreal injection of 0.75 mg of bevacizumab as monotherapy or complementary to laser therapy. In 24 hours, all injected eyes showed regression of the tunica vasculosa lentis and iris vessel engorgement and disappearance of iris rigidity. In addition, plus disease and retinal proliferation began to regress. None of the eyes required additional treatment. Follow-up of up to 10 months  相似文献   
27.
The possibility of a correlation between dengue virus genotype groups and disease severity is currently under discussion. The objective of this investigation was to identify any immunogenic difference between the American and Asian dengue 2 virus genotypes through the study of antibody development (virus-binding immunoglobulin G and neutralizing antibodies) in mice. Differences in the neutralization pattern between the strains studied were observed, suggesting the presence of slight antigenic variations among them. The lack of recognition of one of the Asian genotype strains was remarkable.  相似文献   
28.
BACKGROUND: Portugal has one of the highest mortality rates from stroke, a high prevalence of hypertension and probably a high salt intake level. AIM: To evaluate Portuguese salt intake levels and their relationship to blood pressure and arterial stiffness in a sample of four different adult populations living in northern Portugal. METHODS: A cross-sectional study evaluating 24-hour urinary excretion of sodium (24 h UNa+), potassium and creatinine, blood pressure (BP), and pulse wave velocity (PWV) as an index of aortic stiffness in adult populations of sustained hypertensives (HT), relatives of patients with previous stroke (Fam), university students (US) and factory workers (FW), in the context of their usual dietary habits. RESULTS: We evaluated a total of 426 subjects, mean age 50 +/- 22 years, 56% female, BMI 27.9+/-5.1, BP 159/92 mmHg, PWV 10.4+/-2.2 m/s, who showed mean 24h UNa+ of 202 +/- 64 mmol/d, corresponding to a daily salt intake of 12.3 g (ranging from 5.2 to 24.8). The four groups were: HT: n = 245, 49 +/- 18 years, 92% of those selected, 69% treated, BP 163/94 mmHg, PWV 11.9 m/s, 24 h UNa+ 212 mmol/d, i.e. 12.4 g/d of salt); Fam: n = 38, 64 +/- 20 years, 57 % of those selected, BP 144/88 mmHg, PWV 10.5 m/s, 24 h UNa+ 194 mmol/d, i.e. 11.1 g/d of salt; US: n = 82, 22 +/- 3 years, 57% of those selected, BP 124/77 mmHg, PWV 8.7 m/s, 24h UNa+ 199 mmol/d, i.e. 11.3 g/d of salt; FW: n = 61, 39 9 years, 47% of those selected, BP 129/79 mmHg, PWV 9.5 m/s, 24 h UNa+ 221 mmol/d, i.e. 12.9 g/d of salt. The ratio of urinary sodium/potassium excretion (1.9 (0.4) was significantly higher in HT than the other three groups. In the 426 subjects, 24h UNa+ correlated significantly (p < 0.01) with systolic BP (r = 0.209) and with PWV (r=0.256) after adjustment for age and BP. Multivariate analysis showed that BP, age and 24h UNa+ correlated independently with PWV taken as a dependent variable. CONCLUSIONS: Four different Portuguese populations showed similarly high mean daily salt intake levels, almost double those recommended by the WHO. Overall, high urinary sodium excretion correlated consistently with high BP levels and appeared to be an independent determining factor of arterial stiffness. These findings suggest that Portugal in general has a high salt intake diet, and urgent measures are required to restrict salt consumption in order to prevent and treat hypertensive disease and to reduce overall cardiovascular risk and events.  相似文献   
29.
Abstract:  We describe a patient with acquired alpha-thalassemia myelodysplastic syndrome (ATMDS). A previously healthy 66-year-old man presented with hemoglobin of 9.3 g/dL, mean corpuscular volume 59 fL, and a bone marrow aspirate with increased erythroid precursors and hypolobulated megakaryocytes. Hemoglobin H inclusions were seen in most red cells after 1% brilliant cresyl blue supravital stain of the peripheral blood. At the molecular level, we identified of a novel mutation in the most 3' exon of the ATRX gene ( C GA→ T GA substitution in codon 2407) resulting in a premature termination codon (p.R2407X). This case provides further evidence for a link between ATRX mutations and ATMDS, and suggests a possible role for the conserved Q-box element in ATRX function.  相似文献   
30.
Ganciclovir (GCV) prophylaxis or pre-emptive therapy significantly reduce the rate of cytomegalovirus (CMV) disease and viremia, but increase the potential for emergence of ganciclovir-resistant CMV strains. The inhibitor concentration at 50% (IC(50)) of GCV from 156 CMV isolates from 59 renal or heart transplant recipients was calculated by means of a rapid phenotypic susceptibility assay. Twenty-seven strains were from 14 patients undergoing GCV therapy. The IC(50) was higher in patients under the prophylaxis regimen. One CMV strain, from a heart transplant recipient, became GCV-resistant after 1 month of therapy (IC(50)=13.7 micromol/l). These data, together with clinical and virological markers, suggested that a switch to foscarnet was necessary, and good evolution was observed. Thus, assay of CMV susceptibility to GCV could be helpful in clinical management.  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