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   1669篇
  免费   89篇
  国内免费   29篇
耳鼻咽喉   40篇
儿科学   57篇
妇产科学   37篇
基础医学   212篇
口腔科学   52篇
临床医学   192篇
内科学   293篇
皮肤病学   38篇
神经病学   100篇
特种医学   160篇
外科学   265篇
综合类   37篇
预防医学   125篇
眼科学   10篇
药学   119篇
中国医学   1篇
肿瘤学   49篇
  2021年   24篇
  2018年   19篇
  2017年   15篇
  2016年   16篇
  2015年   27篇
  2014年   27篇
  2013年   60篇
  2012年   51篇
  2011年   74篇
  2010年   40篇
  2009年   45篇
  2008年   56篇
  2007年   70篇
  2006年   67篇
  2005年   78篇
  2004年   71篇
  2003年   73篇
  2002年   57篇
  2001年   37篇
  2000年   46篇
  1999年   41篇
  1998年   30篇
  1997年   25篇
  1996年   40篇
  1995年   21篇
  1994年   22篇
  1993年   13篇
  1992年   26篇
  1991年   31篇
  1990年   32篇
  1989年   26篇
  1988年   33篇
  1987年   41篇
  1986年   34篇
  1985年   39篇
  1984年   34篇
  1983年   24篇
  1982年   24篇
  1981年   21篇
  1980年   16篇
  1979年   24篇
  1978年   15篇
  1977年   16篇
  1976年   19篇
  1975年   22篇
  1974年   16篇
  1973年   13篇
  1972年   15篇
  1971年   16篇
  1970年   18篇
排序方式: 共有1787条查询结果,搜索用时 0 毫秒
101.
102.

Background  

Fractures of the intertrochanteric hip are common and the treatment of unstable fractures generally requires an operative approach. In elderly patients, osteoporosis makes internal fixation problematic and frequently contributes to failed fixation and poor clinical results. We have attempted to apply the Less Invasive Stabilization System (LISS) in reverse position for the repair of intertrochanteric hip fractures in elderly patients with osteoporotic bones. A retrospective review is presented of the cases of 28 elderly patients with stable and unstable fractures of the intertrochanteric hip treated using the reverse LISS.  相似文献   
103.
We describe the case report of a 25-year-old female who presented with signs and symptoms of bowel obstruction status after laparoscopic treatment of an ectopic pregnancy performed 3 weeks earlier. The patient underwent laparoscopic lysis of adhesions and reduction of small bowel obstruction. This case report presents an atypical cause of postoperative bowel obstruction and reviews the current literature regarding laparoscopic surgery as an approach for treatment.  相似文献   
104.
Pharmacokinetics of hydroxyethyl starch   总被引:8,自引:0,他引:8  
Hydroxyethyl starch has recently become the subject of renewed interest because of the introduction of a new specification, hydroxyethyl starch 130/0.4, as well as the clinical availability of a solution using a previous hydroxyethyl starch type (hydroxyethyl starch 670/0.75) with a carrier other than 0.9% saline.Various types of hydroxyethyl starch show different pharmacokinetic behaviour. Since hydroxyethyl starch is a polydisperse solution acting as a colloid, pharmacodynamic action depends on the number of oncotically active molecules, not on the plasma concentration alone; therefore, solutions with a lower in vivo molecular weight contain more molecules at similar plasma concentrations. On the other hand, high plasma concentrations as well as high in vivo molecular weight can affect blood coagulation, especially factor VIII and von Willebrand factor.Hydroxyethyl starch types with a molar substitution >0.4 accumulate in plasma after repetitive administration, most pronounced with hetastarch (hydroxyethyl starch 670/0.75). Correspondingly, tissue storage as measured by (14)C tracer studies in animals showed significantly higher values for hydroxyethyl starch 200/0.5 compared with hydroxyethyl starch 130/0.4 (about 4-fold at the latest timepoint after the last administration), and considerably higher values for hetastarch compared with both hydroxyethyl starch 130/0.4 and 200/0.5.Hydroxyethyl starch 130/0.4 does not accumulate in plasma after single- and multiple-dose administration in contrast to all other available hydroxyethyl starch specifications. Plasma clearance of hydroxyethyl starch 130/0.4 is at least 20-fold higher than that for hetastarch, and considerably higher than for pentastarch. In patients with renal insufficiency, pharmacokinetic data are only available for hydroxyethyl starch 130/0.4. Cumulative urinary excretion, even in the presence of severe non-anuric renal failure, is higher for hydroxyethyl starch 130/0.4 than values published for older hydroxyethyl starch specifications. Hydroxyethyl starch 130/0.4 may be given to patients with severe renal impairment as long as urine flow is preserved.The pharmacodynamics with respect to the volume effect does not directly mirror pharmacokinetics in the case of hydroxyethyl starch solutions. Equivalent volume efficacy has been proven for hydroxyethyl starch 130/0.4 compared with 200/0.5. Prolonged persistence of hydroxyethyl starch in plasma and tissues can be avoided by using rapidly metabolisable hydroxyethyl starch types with molar substitution <0.5. Influence on coagulation is minimal with hydroxyethyl starch 130/0.4, and no adverse effects on kidney function have been observed even with large repetitive doses when used according to the product information.  相似文献   
105.

Background

Soil-transmitted helminth infections are widespread. Many studies have been published on the topic of deworming. The Lives Saved Tool (LiST) is a software package that uses a deterministic mathematical model to estimate the effect of scaling up interventions on maternal and child health outcomes. This review investigates the scope of available evidence for benefits of deworming treatments in order to inform a decision about possible inclusion of deworming as an intervention in LiST.

Methods

We searched PubMed, the Cochrane Library, and Google Scholar. We included studies that reported pre/post data in children younger than 5 years or pregnant women for outcomes related to mortality and growth. We excluded studies that compared different anthelminthic treatments but did not include a placebo or non-treatment group, and those that did not report post-intervention outcomes. We categorized articles by treated population (children younger than 5 years and pregnant women), experimental versus observational, mass drug administration (MDA) versus treatment, and reported outcome.

Results

We identified 58 relevant trials; 27 investigated children younger than 5 years and 11 investigated pregnant women; one reported on both children younger than 5 years and pregnant women. We conducted meta-analyses of relevant outcomes in children younger than 5 years.

Conclusions

Deworming did not show consistent benefits for indicators of mortality, anemia, or growth in children younger than five or women of reproductive age. We do not recommend including the effect of deworming in the LiST model.
  相似文献   
106.
Nursing theories are typically anthropocentric and emphasize caring for a person as a unitary whole. They maintain the dualisms of human–nonhuman, natural–social and material–ideal. Recent developments in nonhuman ontology question the utility of that approach. One important philosopher in this new materialism is political theorist Jane Bennett. In this paper, I explore Bennett's vital materialism and enchantment as two concepts arising from the nonhuman turn that should inform nursing philosophy. Vital materialism considers the lively power of matter to affect the world and be affected in relations. Enchantment refers to a sense of wonder and captivation with matter. While summarizing her important contributions, I also describe common criticisms and responses. I consider the human as an assemblage of matter as well as the agency or “thing power” of matter external to humans. This has implications for nursing thought and practice, and it can inform a more capacious research methodology. I also discuss how compassion fatigue or burnout and other professional issues may be seen as a form of disenchantment with the material world. I argue that embracing these and other elements of Bennett's new materialist philosophy can help nurses and other health professionals enrich their theories and practice to advance their disciplines and improve care for persons and populations.  相似文献   
107.

Background

Foodborne disease is a significant problem worldwide. Research exploring sources of outbreaks indicates a pronounced role for food workers'' improper health and hygiene practice.

Objective

To investigate food workers'' perceptions of factors that impact proper food safety practice.

Method

Interviews with food service workers in Baltimore, MD, USA discussing food safety practices and factors that impact implementation in the workplace. A social ecological model organizes multiple levels of influence on health and hygiene behavior.

Results

Issues raised by interviewees include factors across the five levels of the social ecological model, and confirm findings from previous work. Interviews also reveal many factors not highlighted in prior work, including issues with food service policies and procedures, working conditions (e.g., pay and benefits), community resources, and state and federal policies.

Conclusion

Food safety interventions should adopt an ecological orientation that accounts for factors at multiple levels, including workers'' social and structural context, that impact food safety practice.  相似文献   
108.

Background

Early breastfeeding is defined as the initiation of breastfeeding within twenty four hours of birth. While the benefits of breastfeeding have been known for decades, only recently has the role of time to initiation of breastfeeding in neonatal mortality and morbidity been assessed.

Objective

To review the evidence for early breastfeeding initiation practices and to estimate the association between timing and neonatal outcomes.

Methods

We systematically reviewed multiple databases from 1963 to 2011. Standardized abstraction tables were used and quality was assessed for each study utilizing the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. Three meta-analyses were conducted for mortality among babies surviving to 48 hours.

Results

We identified 18 studies reporting a direct association between early breastfeeding initiation and neonatal mortality and morbidity outcomes. The results of random effects analyses of data from 3 studies (from 5 publications) demonstrated lower risks of all-cause neonatal mortality among all live births (RR = 0.56 [95% CI: 0.40 – 0.79]) and among low birth weight babies (RR=0.58 [95% CI: 0.43 – 0.78]), and infection-related neonatal mortality (RR = 0.55 [95% CI: 0.36 – 0.84]). Among exclusively breastfed infants, all-cause mortality risk did not differ between early and late initiators (RR = 0.69 [95% CI: 0.27 – 1.75]).

Conclusions

This review demonstrates that early breastfeeding initiation is a simple intervention that has the potential to significantly improve neonatal outcomes and should be universally recommended. Significant gaps in knowledge are highlighted, revealing a need to prioritize additional high quality studies that further clarify the specific cause of death, as well as providing improved understanding of the independent or combined effects of early initiation and breastfeeding patterns.
  相似文献   
109.
The primary aim of this prospective 2-year follow-up study was to investigate the effect of depot medroxyprogesterone acetate (DMPA) on the maintenance of bone mass in women aged 30-45 years. The effects of estrogen or calcium substitution during the second year of follow-up was investigated in seven DMPA users with a high annual bone loss during the first year. The bone mass of 35 users of DMPA and 10 women without hormonal contraception was investigated using peripheral quantitative computed tomography. The baseline cortical and trabecular bone mass (TBM) and the annual change was not different in DMPA users and controls. Over 24 months we measured an increase in TBM of 0.6% and a decrease in cortical bone mass of 0.1% in exposed women. Some but not all of the DMPA users with a bone loss during the first year could be successfully treated with estradiol or calcium. In conclusion, we did not observe an accelerated bone loss in DMPA users aged 30-45 years.  相似文献   
110.
Nutrition assessment is a vital component of the general care of HIV-infected adults. With access to highly active antiretroviral therapy (HAART), HIV infection may become a chronic, manageable disease. Nutritional and metabolic complications traditionally associated with HIV infection such as hypertriglyceridemia, low levels of high-density lipoprotein (HDL) cholesterol, and weight loss continue to occur. However, emerging abnormalities such as regional alterations in body shape (fat re-distribution syndrome or HIV-associated lipodystrophy), increasing body weight, high levels of low-density lipoprotein (LDL) cholesterol, insulin resistance, and other metabolic derangements may also be present. In addition, as patients are living longer, they may be susceptible to other age-related diseases such as diabetes, cardiovascular disease, and obesity. In this article, we review strategies for nutrition assessment and management in HIV-infected adults. Attention is focused on specific symptoms such as weight loss and diarrhea and specific disorders such as lipodystrophy, micronutrient deficiencies, and dyslipidemia, which commonly affect HIV-infected individuals. Proper attention to nutritional status may help to reduce the burden of disease and promote an enhanced quality of life in HIV-infected individuals.  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