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   7783篇
  免费   458篇
  国内免费   34篇
耳鼻咽喉   132篇
儿科学   110篇
妇产科学   172篇
基础医学   1358篇
口腔科学   858篇
临床医学   474篇
内科学   1501篇
皮肤病学   160篇
神经病学   695篇
特种医学   158篇
外科学   629篇
综合类   23篇
一般理论   1篇
预防医学   816篇
眼科学   100篇
药学   655篇
中国医学   74篇
肿瘤学   359篇
  2024年   11篇
  2023年   67篇
  2022年   185篇
  2021年   256篇
  2020年   166篇
  2019年   235篇
  2018年   316篇
  2017年   197篇
  2016年   238篇
  2015年   267篇
  2014年   411篇
  2013年   466篇
  2012年   662篇
  2011年   755篇
  2010年   346篇
  2009年   282篇
  2008年   511篇
  2007年   508篇
  2006年   410篇
  2005年   392篇
  2004年   324篇
  2003年   282篇
  2002年   207篇
  2001年   119篇
  2000年   119篇
  1999年   111篇
  1998年   46篇
  1997年   33篇
  1996年   17篇
  1995年   20篇
  1994年   15篇
  1993年   14篇
  1992年   51篇
  1991年   36篇
  1990年   38篇
  1989年   20篇
  1988年   23篇
  1987年   10篇
  1986年   10篇
  1985年   12篇
  1984年   7篇
  1982年   8篇
  1981年   5篇
  1979年   11篇
  1977年   4篇
  1974年   6篇
  1973年   6篇
  1971年   6篇
  1969年   5篇
  1965年   5篇
排序方式: 共有8275条查询结果,搜索用时 15 毫秒
31.
The role of risk management is vitally important in the hospital. As institutions grow and the field of health care advances into the future, the number of patient-associated risks will continue to multiply. In response, the Joint Commission has changed its policies to reflect the importance of patient outcomes. This new Joint Commission focus, coupled with the increasing number of patient risks, will create the need for health care professionals to recognize their role in risk management. In anticipation of the future, pharmacy has been guiding itself toward that role for some time. With a large portion of the profession participating in activities such as DUE and QA programs, pharmacists can be a useful resource to the risk manager. Participation in retrospective analysis such as ADRs and peer review committees also aids the pharmacy profession in establishing guidelines that will decrease future patient risks. Future trends in drug development will increase the pharmacist's role in drug selection, in an effort to ensure both safety and cost containment. The profession's continuing development and implementation of practice standards will ensure that pharmacy remains dedicated to improving patient outcomes and decreasing patient risks. In addition, by learning to use the risk manager as both a source of information and a partner in identifying pharmacy-related areas of risk, the pharmacy profession will be able to continue its pursuit of improved quality of patient care.  相似文献   
32.
A number of neurotoxins from venoms of invertebrates and plants are ligands for voltage-gated Na+ channels and are useful tools for studying Na+ channel function and structure. Using whole-cell recordings from vagal afferent nodose neurons, we studied neurotoxins that target Na+ channels. We asked whether Ts3 (an α-scorpion toxin) and/or veratridine (a lipid-soluble toxin), could modify the TTX-resistant Na+ current generated by vagal afferent nodose neurons. Nodose TTX-resistant current was not affected by Ts3, whereas Ts3 slowed inactivation of the current generated by TTX-sensitive current component. We found that veratridine inhibited the TTX-resistant Na+ currents on rat nodose neurons. Interestingly, veratridine-modified Na+ channels developed a persistent current that accounted for the large tail current observed. We propose that veratridine modifies TTX-resistant Na+ channels through a mechanism distinct from its actions on other voltage-gated Na+ channels.  相似文献   
33.
34.
35.
OBJECTIVE: To determine the coverage and focus of cervical cancer screening (Pap smears) in a population-based sample in Brazil. METHODS: Cross-sectional cluster survey covering 1730 women aged 20 years or older with a history of sexual activity. Information was collected on social, demographic and behavioral variables, knowledge of and use of the Pap test. RESULTS: Of women aged 25-59 years, who are the target population of the national cervical cancer screening program, 78.7% had had at least one Pap test in their lifetime, and 68.8% had had a Pap test in the last 3 years. Statistics for focus of the program showed that of the 637 women who reported having a Pap test in the last year, only 20.6% actually required one. The remainder were either outside the age range or had had another test less than 30 months previously. Prevalence of not having been tested in the previous 3 years was highest among black (41.7%) and low-income women (64.3%), and among those at greatest risk for cervical cancer (62.3% for women with three or more risk factors). Focus was inversely related to socioeconomic status. CONCLUSION: Coverage rates were similar to those reported in other national studies, but this is the first report to examine the focus of the national program. We show that 8 of every 10 Pap tests were not necessary. Coverage levels remain unacceptably low among women of low socioeconomic status and those at greatest risk for cervical cancer.  相似文献   
36.
The hippocampus plays a main role in regulating stress response in humans, but is itself highly sensitive to neurotoxic effects of repeated stressful episodes. Hippocampal atrophy related to experimental stress has been reported in laboratory studies in animals. Several controlled brain imaging studies have also shown hippocampal abnormalities in psychiatric disorders, including posttraumatic stress disorder (PTSD), major depressive disorder (MDD), and borderline personality disorder (BPD). This paper reviews the physiological role of the hippocampus in stress circuitry and the effects of stress on cognitive functions mediated by the hippocampus. We also review brain imaging studies investigating hippocampus in PTSD, MDD, and BPD. This literature suggests that individuals with PTSD, MDD, and BPD may suffer hippocampal atrophy as a result of stressors associated with these disorders. Prospective, longitudinal studies will be needed in high-risk offspring and first-episode subjects to explore the relationship between stress and hippocampal atrophy in these neuropsychiatric illnesses.  相似文献   
37.
Bites of brown spiders (Loxosceles spp.) are responsible for dermonecrotic lesions and potentially systemic envenoming that can lead to death. The only effective therapy is the use of the antivenom, usually produced in horses. However, little is known about the consequences of the systematic use of the Loxosceles venom and adjuvants and of the bleedings on antivenom-producing horses. Thus, the aim of this study was to evaluate the clinical changes in horses in their first immunization protocol for Loxosceles antivenom production. Eleven healthy horses, never immunized, were evaluated in three different periods: T0 (before immunization); T1 (after their first venom immunization); and T2 (after their first bleeding). Horses were clinically evaluated, sampled for blood, and underwent electrocardiographic (ECG) recordings. Several suppurated subcutaneous abscesses occurred due to the use of Freund’s adjuvants and thrombophlebitis due to systematic venipunctures for the bleeding procedures. ECG showed arrhythmias in few horses in T2, such as an increase in T and R waves. In summary, the immunization protocol impacted on horses’ health, especially after bleeding for antivenom procurement.  相似文献   
38.
BackgroundCoronary tomography angiography (CTA) has been mainly used for chest pain evaluation in low-risk patients, and few data exist regarding patients at intermediate risk.ObjectiveTo evaluate the performance of serial measures of sensitive troponin and CTA in intermediate-risk patients.MethodsA total of 100 patients with chest pain, TIMI risk scores of 3 or 4, and negative troponin were prospectively included. All patients underwent CTA and those with coronary stenosis ≥ 50% were referred to invasive coronary angiography. Patients with coronary lesions <50% were discharged and contacted 30 days later by a telephone call to assess clinical outcomes. Outcomes were hospitalization, death, and myocardial infarction at 30 days. The comparison between methods was performed by Kappa agreement test. The performance of troponin measures and CTA for detecting significant coronary lesions and clinical outcomes was calculated. Results were considered statistically significant when p < 0.05.ResultsCoronary stenosis ≥ 50% on CTA was found in 38% of patients and significant coronary lesions on coronary angiography were found in 31 patients. Two clinical events were observed. Kappa agreement analysis showed low agreement between troponin measures and CTA in the detection of significant coronary lesions (kappa = 0.022, p = 0.78). The performance of CTA for detecting significant coronary lesions on coronary angiography or for predicting clinical events at 30 days was better than sensitive troponin measures (accuracy of 91% versus 60%).ConclusionCTA performed better than sensitive troponin measures in the detection of significant coronary disease in patients with chest pain and intermediate risk for cardiovascular events.  相似文献   
39.
Knipp GT  Liu B  Audus KL  Fujii H  Ono T  Soares MJ 《Placenta》2000,21(4):367-375
The placenta forms a selective barrier that is able to transport nutrients that are of critical use to the fetus. Delivery of essential fatty acids to the fetus is dependent upon transplacental transport and provides the backbone for the biosynthesis of biological membranes, myelin and various signalling molecules. The primary objective of this research was to elucidate the expression patterns of genes that regulate fatty acid transport across the placenta. Several fatty acid transport regulatory genes have been identified in the rat including; cytoplasmic heart fatty acid binding protein (hFABP), plasma membrane fatty acid binding protein (FABPpm), fatty acid translocase (FAT) and fatty acid transport protein (FATP). In this study, we have elucidated temporal and spatial expression patterns for these genes in the rat placenta and in cell culture models of the rat placenta by Northern blot, RT-PCR, Western blot and/or by in situ hybridization analyses. Expression of hFABP was specific to the labyrinth zone, the main barrier and site of transplacental transport in the rat placenta. In addition, the levels of hFABP expression increased with gestational age, suggesting a growing requirement for fatty acid transport with advancing stages of pregnancy. FABPpm, FAT and FATP are expressed in both the junctional and labyrinth zones of the rat placenta. FAT was predominantly localized to the labyrinth zone by in situ hybridization analysis. The placental cell expression patterns of the genes involved in fatty acid transport were supported by our observations of HRP-1 (labyrinth zone) and Rcho-1 (junctional zone) trophoblast cell culture models. Given their cell surface location, we predict that FABPpm, FAT and FATP potentially participate in placental fatty acid uptake. The predominant expression of hFABP and FAT in the labyrinth zone of the chorioallantoic placenta implicates hFABP and FAT in the transplacental movement of fatty acids from maternal to fetal compartments.  相似文献   
40.
Ketogenic diets (KD) are dietary strategies low in carbohydrates, normal in protein, and high, normal, or reduced in fat with or without (Very Low-Calories Ketogenic Diet, VLCKD) a reduced caloric intake. KDs have been shown to be useful in the treatment of obesity, metabolic diseases and related disorders, neurological diseases, and various pathological conditions such as cancer, nonalcoholic liver disease, and chronic pain. Several studies have investigated the intracellular metabolic pathways that contribute to the beneficial effects of these diets. Although epigenetic changes are among the most important determinants of an organism’s ability to adapt to environmental changes, data on the epigenetic changes associated with these dietary pathways are still limited. This review provides an overview of the major epigenetic changes associated with KDs.  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