全文获取类型
收费全文 | 2099篇 |
免费 | 112篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 169篇 |
妇产科学 | 85篇 |
基础医学 | 322篇 |
口腔科学 | 44篇 |
临床医学 | 153篇 |
内科学 | 414篇 |
皮肤病学 | 45篇 |
神经病学 | 130篇 |
特种医学 | 62篇 |
外科学 | 224篇 |
综合类 | 43篇 |
一般理论 | 2篇 |
预防医学 | 137篇 |
眼科学 | 110篇 |
药学 | 91篇 |
中国医学 | 4篇 |
肿瘤学 | 160篇 |
出版年
2023年 | 11篇 |
2022年 | 20篇 |
2021年 | 38篇 |
2020年 | 28篇 |
2019年 | 37篇 |
2018年 | 61篇 |
2017年 | 42篇 |
2016年 | 52篇 |
2015年 | 40篇 |
2014年 | 65篇 |
2013年 | 102篇 |
2012年 | 148篇 |
2011年 | 161篇 |
2010年 | 78篇 |
2009年 | 86篇 |
2008年 | 137篇 |
2007年 | 173篇 |
2006年 | 126篇 |
2005年 | 117篇 |
2004年 | 134篇 |
2003年 | 100篇 |
2002年 | 91篇 |
2001年 | 47篇 |
2000年 | 47篇 |
1999年 | 39篇 |
1998年 | 18篇 |
1997年 | 10篇 |
1996年 | 19篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 15篇 |
1989年 | 14篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 15篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 10篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1971年 | 4篇 |
1970年 | 2篇 |
排序方式: 共有2215条查询结果,搜索用时 31 毫秒
41.
42.
Sodhi KS Sidhu R Gulati M Saxena A Suri S Chawla Y 《Journal of gastroenterology and hepatology》2005,20(10):1488-1493
Background: The purpose of the present study was to compare iissue harmonic imaging (THI) and conventional sonography in focal hepatic lesions. Methods: Fifty patients with focal hepatic lesions were enrolled for study. Conventional grayscale and THI was performed in all the patients and two sets of images of the lesions were recorded (one each for THI and conventional) and assessed for fluid–solid differentiation, detail and overall image quality. These images were compared with conventional sonographic images and graded better, same or worse as per the case. Lesions were confirmed by fine‐needle aspiration cytology (FNAC)/surgery/other modalities such as computed tomography (CT) or magnetic resonance imaging (MRI). Results: Out of 50 patients with focal hepatic lesions, 21 patients had metastatic lesions (two single; 19 multiple) five patients had hepatocellular carcinoma (HCC), five patients had hydatid cysts, nine had simple hepatic cyst whereas five patients had liver abscess, three had focal fatty infiltration; and lymphoma and hemangioma were seen in one patient each. The first observer ranked THI better than standard sonography in 40 patients (80%) for fluid–solid differentiation, in 38 (76%) for detail and in 39 (78%) for overall image quality. The second observer ranked THI better than standard sonography in 39 patients (78%) for fluid–solid differentiation, in 40 (80%) for detail and in 42 (84%) for overall image quality. Tissue harmonic imaging provided additional information in eight patients (16%) and resulted in treatment alteration in three patients (6%). Conclusion: Tissue harmonic imaging was significantly better than conventional sonography for fluid–solid differentiation, detail and total image quality in focal hepatic lesions, especially in obese patients and patients with poor acoustic window. 相似文献
43.
Previous results have shown that salmon calcitonin (sCT), a peptide in rat brain and pituitary gland, inhibits basal and TRH-stimulated PRL release and reduces PRL mRNA levels in isolated anterior pituitary cells of adult rats in culture. Rat milk contains a variety of neuropeptides and hormones, some of which are absorbed in bioactive form to exert endocrine influences in the developing offspring. The present studies were undertaken to investigate whether a CT-like peptide is present in rat milk. Circulating PRL levels in neonatal rats are low, and there is an abrupt increase in the basal secretion of this hormone at weaning. A second objective was to examine whether CT plays a role in the regulation of PRL secretion in neonatal animals. A sensitive and specific RIA for sCT was developed and used to assay rat milk on various days of lactation for sCT-like immunoreactivity. sCT-like activity was present in the water-soluble (infranatant) fraction of milk throughout lactation in concentrations as high as 1589 pg/ml. There were no statistically significant differences in immunoreactive levels of the peptide in milk samples from different days of lactation. sCT-like immunoreactivity in rat milk infranatant coeluted with synthetic sCT on reverse phase HPLC, and these HPLC fractions inhibited basal PRL release when added to cultures of anterior pituitary cells. This inhibition of PRL release by the sCT-immunoreactive HPLC fractions was comparable to that exerted by equivalent concentrations of synthetic sCT. Newborn rats were injected sc with 10 microliters normal rabbit serum or anti-sCT serum from the day of birth until postpartum day 10. The rats were killed on day 11, and their sera were analyzed for PRL. Anti-sCT-injected rats showed a significant increase in serum PRL levels compared to those in untreated or normal serum-treated rats. These results demonstrate that a CT-like peptide, which is a potent inhibitor of PRL release, is present in rat milk throughout lactation, and that passive immunization with a highly specific anti-sCT serum leads to an increase in serum PRL levels in neonatal rats. CT, possibly of milk origin, may be a physiologically relevant PRL-inhibiting factor during the neonatal period. 相似文献
44.
Summary
Background Increasing physician case volumes are documented to reduce costs and improve outcomes for many surgical procedures but not
for medical conditions such as pneumonia that consume significant health care resources.
Objective This study explored the association between physicians’ inpatient pneumonia case volume and cost per discharge.
Design The design was a retrospective, population-based, cross-sectional study, using National Health Insurance administrative claims
data.
Setting The setting was Taiwan.
Participants The participants were a universal sample of 270,002 adult, acute pneumonia hospitalizations, during 2002–2004, excluding transferred
cases and readmissions.
Measurements Hierarchical linear regression modeling was used to examine the association of physician’s volume (three volume groups, designed
to classify patients into approximately equal sized groups) with cost, adjusting for hospital random effects, case severity,
physician demographics and specialty, hospital characteristics, and geographic location.
Results Mean cost was NT$2,255 (US$1 = NT$33 in 2004) for low-volume physicians (≤100 cases) and NT$1,707 for high-volume physicians
(≥316 cases). The adjusted patient costs for low-volume physicians were higher (US$264 and US$235 than high- and medium-volume
physicians, respectively; both P < .001), with no difference between high- and medium-volume physicians. High-volume physicians had lower in-hospital mortality
and 14-day readmission rates than low-volume physicians.
Conclusions Data support an inverse volume–cost relationship for pneumonia care. Decision processes and clinical care of high-volume physicians
versus low-volume physicians should be studied to develop effective care algorithms to improve pneumonia outcomes and reduce
costs. 相似文献
45.
Au R Seshadri S Wolf PA Elias M Elias P Sullivan L Beiser A D'Agostino RB 《Experimental aging research》2004,30(4):333-358
A previous publication presented normative data on neuropsychological tests stratified by age, gender, and education based on the Original Cohort of the Framingham Heart Study. Many contemporary investigations include subject samples with higher levels of education, a factor known to affect cognitive performance. Secular change in education prompted the reexamination of norms in the children of the Original Cohort. The study population consisted of 853 men and 988 women from the Offspring Study, free of clinical neurological disease, who underwent a neuropsychological examination, which included tests given to their parents in 1974 to 1976 as well as additional newer tests to provide a more comprehensive battery. The Offspring population overall was more evenly distributed by gender and better educated. Their performance on cognitive tests was superior to that of the Original Cohort. Multivariable analyses revealed that more years of education explained only a part of the cohort differences. These findings suggest that continued surveillance of each generation is necessary to document the impact that unique social and economic variables have on cognitive function. Here, the authors provide updated normative data. 相似文献
46.
Development of an opinion leader-led HIV prevention intervention among alcohol users in Chennai, India. 总被引:1,自引:0,他引:1
Sudha Sivaram Aylur K Srikrishnan Carl A Latkin Sethulakshmi C Johnson Vivian F Go Margaret E Bentley Suniti Solomon David D Celentano 《AIDS education and prevention》2004,16(2):137-149
In 1999, we began a community-based randomized controlled prevention trial in Chennai, which aims to test the efficacy of HIV prevention messages disseminated through members of an individual's social group called community popular opinion leaders, or CPOLs. We targeted patrons of 100 bars or wine shops in the city of Chennai, India. In this article we report on the process of development of an HIV prevention intervention for wine shop patrons. First, we conducted detailed ethnography to understand social norms and CPOL and social network characteristics, including 41 in-depth interviews among wine shop patrons and gatekeepers. Second, we tailored a generic HIV education training manual to appropriately address the needs of Chennai wine shop patrons. Field-testing involved 16 focus groups with wine shop patrons and 12 sessions of participant observations in wine shops. Finally, we piloted the intervention to determine the appropriateness of the training program and its content among wine shop patrons. Our ethnographic data indicated that wine shops are a common meeting place for men. We were able to identify CPOLs influential in these settings and train them to deliver appropriate prevention messages to their close friends and associates. We found that HIV prevention messages in this population need to dispel misperceptions about HIV transmission, provide strategies and skills to adopt and sustain condom use, and target the role of alcohol in sexual behavior. We outline specific lessons we learned in intervention development in this population. 相似文献
47.
Paul A. Schulte Rebecca J. Guerin Anita L. Schill Anasua Bhattacharya Thomas R. Cunningham Sudha P. Pandalai Donald Eggerth Carol M. Stephenson 《American journal of public health》2015,105(8):e31-e44
Action to address workforce functioning and productivity requires a broader approach than the traditional scope of occupational safety and health. Focus on “well-being” may be one way to develop a more encompassing objective. Well-being is widely cited in public policy pronouncements, but often as “. . . and well-being” (e.g., health and well-being). It is generally not defined in policy and rarely operationalized for functional use. Many definitions of well-being exist in the occupational realm. Generally, it is a synonym for health and a summative term to describe a flourishing worker who benefits from a safe, supportive workplace, engages in satisfying work, and enjoys a fulfilling work life. We identified issues for considering well-being in public policy related to workers and the workplace.Major changes in population demographics and the world of work have significant implications for the workforce, business, and the nation.1–8 New patterns of hazards, resulting from the interaction of work and nonwork factors, are affecting the workforce.1,2,8–11 As a consequence, there is a need for an overarching or unifying concept that can be operationalized to optimize the benefits of work and simultaneously address these overlapping hazards. Traditionally, the distinct disciplines of occupational safety and health, human resources, health promotion, economics, and law have addressed work and nonwork factors from specialized perspectives, but today changes in the world of work require a holistic view.There are numerous definitions of well-being within and between disciplines, with subjective and objective orientations addressing such conceptualizations as happiness, flourishing, income, health, autonomy, and capability.12–22 Well-being is widely cited in public policy pronouncements, but often in the conjunctive form of “. . . and well-being” (as in health and well-being). It is rarely defined or operationalized in policy.In this article, we consider if the concept of “well-being” is useful in addressing contemporary issues related to work and the workforce and, if so, whether it can be operationalized for public policy and what the implications are of doing so. We discuss the need to evaluate a broad range of work and nonwork variables related to worker health and safety and to develop a unified approach to this evaluation. We discuss the potential of well-being to serve as a unifying concept, with focus on the definitions and determinants of well-being. Within this part of the discussion, we touch on topics of responsibility for well-being. We also explore issues of importance when one is incorporating well-being into public policy. We present examples of the incorporation of the principles of well-being into public policy, and the results thus far of the implementation of such guidance. We describe research needs for assessing well-being, particularly the need to operationalize this construct for empirical analysis. We aim to contribute to the ongoing efforts of occupational safety and health and public health researchers, practitioners, and policymakers to protect working populations. 相似文献
48.
Four major compounds were separated and identified from the methanol extracts of Nerium indicum flowers (Arali) using HPLC and mass spectral data. Through mass data, the chemical structures were elucidated as: trans5-O-caffeoylquinic acid (1), quercetin-3-O- rutinoside (2), luteolin-5-O-rutinoside (3) and luteolin-7-O-rutinoside (4). In addition, the cis isomers of 5-O-caffeoylquinic acid in Nerium indicum flowers were confirmed by Mass, HPLC and UV. The structures of these compounds confirmed with the help of liquid chromatography mass spectrometry. 相似文献
49.
Background: A sugar rich diet induces inflammation and insulin resistance (IR) mainly through gut microbiota alteration. Gut dysbiosis increases lipopolysaccharide (LPS) and reduces propionate and butyrate levels to impair the insulin signalling cascades by different molecular pathways, which progresses into IR. The present study was designed to investigate the effect of spectrum specific antibiotics on the modulation of gut microbiota and its signalling pathways to prevent diet-induced diabetes. Methods: Healthy male Wistar rats were divided into a non-diabetic group with a control diet (CD), a diabetic group with a high sucrose diet (HSD) and two antibiotic fed groups (linezolid and cefdinir; administered by oral gavage) along HSD. Physiological, biochemical, inflammatory and microbiome parameters were examined. Results: Cefdinir administration in HSD rats reduced fasting glucose, serum triglyceride, and cholesterol levels compared to HSD alone. In addition, cefdinir reduced serum LPS by decreasing the population of Gram-negative phyla, that is, Bacteroidetes and Proteobacteria in the fecal content. Furthermore, cefdinir treatment decreased hepatic/ileal/colonic Tlr4, Nlr1, and Nf-κB at the mRNA level. Moreover, cefdinir-treated rats had shown increased fecal butyrate and propionate and reduced acetate levels compared to HSD alone. Cefdinir treatment also induced ileal/colonic Gpr43 and Glut4 at the mRNA level after 12 weeks of administration. Conclusions: Taken together, these data suggest that administration of a Gram-negative spectrum antibiotic, that is, cefdinir, has modulated the gut microbiota, and reduced serum LPS and triglycerides, which prevented the progression of IR and inflammation in HSD rats.A sugar rich diet induces inflammation and insulin resistance (IR) mainly through gut microbiota alteration. 相似文献
50.
Succinic dehydrogenase activity of the DMBA induced tumor explants cultured with or without hormones was assessed histochemically while receptors for estrogen (ER) and progesterone (PgR) were estimated from the cytosol fraction of the tumor tissue. Tumor regression following ovariectomy (OVX) was kept as the end point for determining hormone dependency. By in vitro method positive correlation was observed in 5 of 6 responsive or hormone dependent tumors, and 13 out of 14 independent tumors. Presence of receptors (ER + PgR, PgR) correlated with responsiveness in 4 of 6 tumors while their absence in the non-responsive group correlated in 6 of 14 tumors. Prolactin responsive tumors did not regress following OVX even if ER + PgR or ER/PgR were present. Using the same tumor tissue the results of hormone dependency by the two methods were identical in only 9 of 20 tumors. 相似文献