全文获取类型
收费全文 | 2170593篇 |
免费 | 153588篇 |
国内免费 | 3199篇 |
专业分类
耳鼻咽喉 | 31324篇 |
儿科学 | 72284篇 |
妇产科学 | 59026篇 |
基础医学 | 307611篇 |
口腔科学 | 59345篇 |
临床医学 | 191020篇 |
内科学 | 423035篇 |
皮肤病学 | 48668篇 |
神经病学 | 167670篇 |
特种医学 | 86505篇 |
外国民族医学 | 859篇 |
外科学 | 331538篇 |
综合类 | 44912篇 |
现状与发展 | 2篇 |
一般理论 | 618篇 |
预防医学 | 158670篇 |
眼科学 | 48975篇 |
药学 | 166674篇 |
9篇 | |
中国医学 | 4683篇 |
肿瘤学 | 123952篇 |
出版年
2018年 | 22407篇 |
2017年 | 17199篇 |
2016年 | 19066篇 |
2015年 | 21451篇 |
2014年 | 29614篇 |
2013年 | 44554篇 |
2012年 | 61041篇 |
2011年 | 64622篇 |
2010年 | 38503篇 |
2009年 | 36322篇 |
2008年 | 60970篇 |
2007年 | 65283篇 |
2006年 | 66154篇 |
2005年 | 63961篇 |
2004年 | 62020篇 |
2003年 | 59946篇 |
2002年 | 58412篇 |
2001年 | 111560篇 |
2000年 | 115524篇 |
1999年 | 97254篇 |
1998年 | 25295篇 |
1997年 | 22651篇 |
1996年 | 22998篇 |
1995年 | 21669篇 |
1994年 | 20177篇 |
1993年 | 18869篇 |
1992年 | 75309篇 |
1991年 | 72909篇 |
1990年 | 71429篇 |
1989年 | 68369篇 |
1988年 | 62465篇 |
1987年 | 61106篇 |
1986年 | 57169篇 |
1985年 | 54435篇 |
1984年 | 40107篇 |
1983年 | 33739篇 |
1982年 | 19024篇 |
1981年 | 17077篇 |
1979年 | 35778篇 |
1978年 | 24447篇 |
1977年 | 21242篇 |
1976年 | 19189篇 |
1975年 | 21263篇 |
1974年 | 24757篇 |
1973年 | 23837篇 |
1972年 | 22355篇 |
1971年 | 20591篇 |
1970年 | 19271篇 |
1969年 | 18050篇 |
1968年 | 16198篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Alexander Real Chierika Ukogu Divya Krishnamoorthy Nicole Zubizarreta Samuel K. Cho Andrew C. Hecht James C. Iatridis 《The spine journal》2019,19(2):225-231
Background Context
Low back pain (LBP) is a common complaint in clinical practice of multifactorial origin. Although obesity has been thought to contribute to LBP primarily by altering the distribution of mechanical loads on the spine, the additional contribution of obesity-related conditions such as diabetes mellitus (DM) to LBP has not been thoroughly examined.Purpose
To determine if there is a relationship between DM and LBP that is independent of body mass index (BMI) in a large cohort of adult survey participants.Study Design
Retrospective analysis of prospectively collected National Health and Nutrition Examination Survey (NHANES) data to characterize associations between LBP, DM, and BMI in adults subdivided into 6 subpopulations: normal weight (BMI 18.5–25), overweight (BMI 25–30), and obese (BMI >30) diabetics and nondiabetics. Diabetes was defined with glycohemoglobin A1c (HbA1c) ≥6.5%.Patient Sample
11,756 participants from NHANES cohort.Outcome Measures
Percentage of LBP reported.Methods
LBP reported in the 1999-2004 miscellaneous pain NHANES questionnaire was the dependent variable examined. Covariates included HbA1c, BMI, age, and family income ratio to poverty as continuous variables as well as race, gender, and smoking as binary variables. Individuals were further subdivided by weight class and diabetes status. Regression and graphical analyses were performed on the study population as a whole and also on subpopulations.Results
Increasing HbA1c did not increase the odds of reporting LBP in the full cohort. However, multivariate logistic regression of the 6 subpopulations revealed that the odds of LBP significantly increased with increasing HbA1c levels in normal weight diabetics. No other subpopulations reported significant relationships between LBP and HbA1c. LBP was also significantly associated with BMI for normal weight diabetics and also for obese subjects regardless of their DM status.Conclusions
LBP is significantly related to DM status, but this relationship is complex and may interact with BMI. These results support the concept that LBP may be improved in normal weight diabetic subjects with improved glycemic control and weight loss, and that all obese LBP subjects may benefit from improved weight loss alone. 相似文献82.
Y. Ermias I.A. Morgan K.M. Curtis M.K. Whiteman L.G. Horton L.B. Zapata 《Contraception》2019,99(5):300-305
ObjectiveIdentify factors associated with healthcare providers' frequency of depot medroxyprogesterone acetate (DMPA) provision to adolescents.Study designWe analyzed data from surveys mailed to a nationally representative sample of public-sector providers and office-based physicians (n=1984). We estimated adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of factors associated with frequent DMPA provision to adolescents in the past year.ResultsAlthough most providers (>95%) considered DMPA safe for adolescents, fewer reported frequent provision (89% of public-sector providers; 64% of office-based physicians). Among public-sector providers, factors associated with lower odds of frequent provision included working in settings without Title X funding (aOR 0.44, 95% CI 0.30–0.64), reporting primary care as their primary clinical focus versus reproductive or adolescent health (aOR 0.42, 95% CI 0.28–0.61), and providing fewer patients with family planning services. Among office-based physicians, factors associated with lower odds of frequent provision included specializing in obstetrics/gynecology (aOR 0.50, 95% CI 0.27–0.91) and family medicine (aOR 0.21, 95% CI 0.09–0.47) versus adolescent medicine, completing training ≥15 versus <5 years ago (aOR 0.27, 95% CI 0.09–0.83), and reporting that 0–24% of patients pay with Medicaid or other government healthcare assistance versus ≥50% (aOR 0.23, 95% CI 0.09–0.61). The reason most commonly reported by providers for infrequent DMPA provision was patient preference for another method.ConclusionsWhile most providers reported frequently providing DMPA to adolescents, training on evidence-based recommendations for contraception, focused on subgroups of providers with lower odds of frequent DMPA provision, may increase adolescents' access to contraception.ImplicationsAlthough >95% of providers considered depot medroxyprogesterone (DMPA) a safe contraceptive for adolescents, only 89% of public-sector providers and 64% of office-based physicians reported frequently providing DMPA to adolescents. Provider training on evidence-based recommendations for contraception counseling and provision may increase adolescents' access to DMPA and all methods of contraception. 相似文献
83.
B. Siska I. Machac P. Dolecek J. Martiska 《Pharmaceutical development and technology》2019,24(1):80-88
Rheological behaviour of pharmaceutical semisolid preparations significantly affects manufacturing process, administration, stability, homogeneity of incorporated drug, accuracy of dosing, adhesion in the place of application, drug release, and resulting therapeutic effect of the product. We performed test of consistency by penetrometry, rotational, oscillation and creep tests, and squeeze and tack tests of model samples to introduce methods suitable for characterization and comparison of semisolids in practice. Penetrometry is a simple method allowing sorting the semisolids to low and high stress-resistant materials but deficient for rheological characterization of semisolids. Value of yield stress, generally considered to be appropriate feature of semisolids, is significantly influenced by the method of testing and the way of evaluation. The hysteresis loops of model semisolids revealed incomplete thixotropy, therefore, three-step thixotropy test was employed. Semisolids showed nonlinear response in the creep phase of tests and partial recovery of structure by storing energy in the recovery phase. Squeeze and tack tests seem to be convenient ways for comparison of semisolids. Our study can contribute to a better understanding of different flow behaviour of semisolids given by different physicochemical properties of excipients and can bring useful approaches to evaluation and comparison of semisolids in practice. 相似文献
84.
P. Anne Scott 《Nursing philosophy》2019,20(3)
This paper revisits a 2003 publication in Nursing Philosophy: The need for accurate perception and informed judgement in determining the appropriate use of the nursing resource: hearing the patient's voice. The author suggests that the basic ideas and focus of this 16‐year‐old paper are still topical and relevant in considerations of nursing care. However, it is also suggested that greater attention to the importance of the nurse–patient relationship in considerations of resource allocation, and potential rationing of nursing care, would have strengthened the original paper. 相似文献
85.
86.
87.
Abdominal Radiology - 相似文献
88.
89.
Alan. B. Franklin Sarah N. Bevins Jeremy W. Ellis Ryan S. Miller Susan A. Shriner J. Jeffrey Root Daniel P. Walsh Thomas J. Deliberto 《Transboundary and Emerging Diseases》2019,66(2):705-714
Using data on waterfowl band recoveries, we identified spatially explicit hotspots of concentrated waterfowl movement to predict occurrence and spatial spread of a novel influenza A virus (clade 2.3.4.4) introduced from Asia by waterfowl from an initial outbreak in North America in November 2014. In response to the outbreak, the hotspots of waterfowl movement were used to help guide sampling for clade 2.3.4.4 viruses in waterfowl as an early warning for the US poultry industry during the outbreak . After surveillance sampling of waterfowl, we tested whether there was greater detection of clade 2.3.4.4 viruses inside hotspots. We found that hotspots defined using kernel density estimates of waterfowl band recoveries worked well in predicting areas with higher prevalence of the viruses in waterfowl. This approach exemplifies the value of ecological knowledge in predicting risk to agricultural security. 相似文献
90.