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   43305篇
  免费   3241篇
  国内免费   92篇
耳鼻咽喉   293篇
儿科学   1654篇
妇产科学   1342篇
基础医学   5396篇
口腔科学   507篇
临床医学   6310篇
内科学   8122篇
皮肤病学   762篇
神经病学   4275篇
特种医学   874篇
外国民族医学   5篇
外科学   3993篇
综合类   483篇
一般理论   42篇
预防医学   5939篇
眼科学   631篇
药学   2747篇
中国医学   47篇
肿瘤学   3216篇
  2024年   54篇
  2023年   421篇
  2022年   684篇
  2021年   1230篇
  2020年   784篇
  2019年   1340篇
  2018年   1487篇
  2017年   1112篇
  2016年   1189篇
  2015年   1307篇
  2014年   1757篇
  2013年   2392篇
  2012年   3612篇
  2011年   3572篇
  2010年   1906篇
  2009年   1713篇
  2008年   2786篇
  2007年   2924篇
  2006年   2702篇
  2005年   2690篇
  2004年   2508篇
  2003年   2166篇
  2002年   2057篇
  2001年   287篇
  2000年   238篇
  1999年   261篇
  1998年   422篇
  1997年   302篇
  1996年   259篇
  1995年   252篇
  1994年   224篇
  1993年   190篇
  1992年   135篇
  1991年   116篇
  1990年   117篇
  1989年   110篇
  1988年   91篇
  1987年   84篇
  1986年   82篇
  1985年   98篇
  1984年   108篇
  1983年   80篇
  1982年   100篇
  1981年   85篇
  1980年   82篇
  1979年   52篇
  1978年   60篇
  1977年   46篇
  1976年   35篇
  1975年   36篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
The objectives of this study were to assess the prevalence and incidence of curable sexually transmitted infections (STI), i.e., gonorrhea, chlamydial infection, or trichomoniasis, in a cohort of HIV-infected women. The study population was derived from women seeking primary care at an outpatient university HIV clinic who were participants in a women's natural history study. Enrollees (n = 225) were predominantly African-American, heterosexually infected, with mean age 35 years. Mean entry CD4+ T cell count was 405 cells/mm3. Over 6% were STI positive at initial screening. Subsequently, the combined curable STI incidence was 4.82/1000 woman-months over a median of 33 months of observation. Of 36 incident STIs, trichomoniasis was most common (n = 32). Predictors for acquisition of a curable STI included absenteeism at scheduled clinic appointments, RR = 1.99 (1.28, 3.08), and a higher CD4+ T cell count, RR = 1.15 (1.0028, 1.3115) for 100 cells. Interventions to prevent curable STI in HIV-infected women are warranted in primary care settings.  相似文献   
992.
993.
994.
Prophylactic antibiotics for urinary tract infections are no longer routinely recommended. A large number of children must be given prophylaxis to prevent one infection and antibiotic resistance is a major concern when treating community-acquired urinary tract infections. The results of three recent significant studies are examined, with focus on the efficacy of prophylaxis, and recommendations are made.  相似文献   
995.
In the context of a global obesity epidemic that has led to an unprecedented burden of non‐communicable disease, the role of food and beverage marketing to children has been scrutinised in numerous studies. This article discusses the broader concept of an obesity‐promoting food environment, before reviewing key, recent (last 5 yr) international research findings with regard to both the prevalence and effects of food and beverage advertising on children's intake. Evidence relating to the two main avenues of food marketing exposure, television, and the Internet, is explored and consideration is given to the differences in consumer experience of these types of promotion. Despite methodological differences and the varying population samples studied, the outcomes are broadly consistent – food advertising is prevalent, it promotes largely energy dense, nutrient poor foods, and even short‐term exposure results in children increasing their food consumption. Policymakers are implored to drive forward meaningful changes in the food environment to support healthier choices and reduce the incidence of obesity and related diseases. This article aims at providing an overview of recent developments in this field. After limiting the search to the last five full years 2009–2014, we searched the following databases: Web of Knowledge and PubMed (keyword search terms used: television, Internet, new media, food advertising, food marketing, children, food intake, energy intake, consumption, and combinations of these terms). In addition we used the references from the articles obtained by this method to check for additional relevant material.  相似文献   
996.
BackgroundTHEMIS (The Effect of Ticagrelor on Health Outcomes in Diabetes Mellitus Patients Intervention Study) (n = 19,220) and its pre-specified THEMIS-PCI (The Effect of Ticagrelor on Health Outcomes in Diabetes Mellitus Patients Intervention Study-Percutaneous Coronary Intervention) (n = 11,154) subanalysis showed, in individuals with type 2 diabetes mellitus (median duration 10.0 years; HbA1c 7.1%) and stable coronary artery disease without prior myocardial infarction (MI) or stroke, that ticagrelor plus aspirin (compared with placebo plus aspirin) produced a favorable net clinical benefit (composite of all-cause mortality, MI, stroke, fatal bleeding, and intracranial bleeding) if the patients had a previous percutaneous coronary intervention.ObjectivesIn these post hoc analyses, the authors examined whether the primary efficacy outcome (cardiovascular death, MI, stroke: 3-point major adverse cardiovascular events [MACE]), primary safety outcome (Thrombolysis In Myocardial Infarction–defined major bleeding) and net clinical benefit varied with diabetes-related factors.MethodsOutcomes were analyzed across baseline diabetes duration, HbA1c, and antihyperglycemic medications.ResultsIn THEMIS, the incidence of 3-point MACE increased with diabetes duration (6.7% for ≤5 years, 11.1% for >20 years) and HbA1c (6.4% for ≤6.0%, 11.8% for >10.0%). The relative benefits of ticagrelor plus aspirin on 3-point MACE reduction (hazard ratio [HR]: 0.90; p = 0.04) were generally consistent across subgroups. Major bleeding event rate (overall: 1.6%) did not vary by diabetes duration or HbA1c and was increased similarly by ticagrelor across all subgroups (HR: 2.32; p < 0.001). These findings were mirrored in THEMIS-PCI. The efficacy and safety of ticagrelor plus aspirin did not differ by baseline antihyperglycemic therapy. In THEMIS-PCI, but not THEMIS, ticagrelor generally produced favorable net clinical benefit across diabetes duration, HbA1c, and antihyperglycemic medications.ConclusionTicagrelor plus aspirin yielded generally consistent and favorable net clinical benefit across the diabetes-related factors in THEMIS-PCI but not in the overall THEMIS population.  相似文献   
997.
Despite the advent of more effective treatments for HIV-1 infection, cognitive impairment is still frequent and questions remain regarding which areas of impairment are more common in the different disease stages. This study investigated cognitive performance over an 8-year period of time in 59 HIV-1 seropositive (HIV-1+) men who were clinically asymptomatic at study entry, in comparison to a cohort of 55 HIV-1 seronegative (HIV-1-) men. Every 6 months we examined cognitive functioning in 5 domains-fine motor speed, attention, verbal memory, executive functioning, and speed of information processing. We found that patients with AIDS scored significantly worse on fine motor speed and speed of information processing than HIV-1- individuals and the HIV-1+ non-AIDS patients. In addition, the HIV-1+ non-AIDS patients performed more poorly than the HIV-1- group on speed of information processing. Depressive symptoms were also associated with diminished performance on measures of attention, executive functioning, and speed of information processing. Further research is needed to examine the effects of disease stage and depression on cognitive impairment in the era of new HIV treatments.  相似文献   
998.
Reduced size at birth in humans has been associated with altered function of the hypothalamic-pituitary-adrenal (HPA) axis in childhood and adult life. Experimentally, maternal undernutrition has also been associated with altered fetal HPA function. However, the relationship between birth size, fetal nutrition, and adult pathophysiology is not clear. We recently have reported that glucose tolerance, blood pressure, and IGF-I levels in adult sheep were more closely associated with birth weight than with nutritional insult in late gestation or with current weight. Here, we report adult HPA function in the same group of animals. Pregnant ewes were severely undernourished for 10 d (UN10) or 20 d (UN20) from 105 d gestation (term, 146 d), or were ad libitum-fed controls. At 30 months, female offspring were subjected to an insulin tolerance test and a CRH plus arginine vasopressin (AVP) challenge. UN20 lambs were lighter at birth, but there were no significant differences in weight at 30 months. Adult UN10 ewes had an increased ACTH response to both CRH+AVP challenge and insulin tolerance test, but no differences in cortisol response. UN10 ewes also demonstrated elevated 11-deoxycortisol concentrations, but lower progesterone concentrations, in response to CRH+AVP challenge. In contrast, the responses of UN20 ewes to these challenges were not different from ad libitum controls. Protein levels of P450(c17) and P450(11beta1) were not significantly different among groups. We conclude that brief maternal undernutrition for 10 d, but not 20 d, in late gestation alters HPA function in adult offspring. In contrast to our previous findings, these HPA effects are independent of birth weight and current weight, suggesting that different mechanisms may be involved in programming different physiological axes.  相似文献   
999.
1000.
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