全文获取类型
收费全文 | 23171篇 |
免费 | 1632篇 |
国内免费 | 62篇 |
专业分类
耳鼻咽喉 | 226篇 |
儿科学 | 890篇 |
妇产科学 | 778篇 |
基础医学 | 2932篇 |
口腔科学 | 238篇 |
临床医学 | 2988篇 |
内科学 | 4041篇 |
皮肤病学 | 515篇 |
神经病学 | 2277篇 |
特种医学 | 489篇 |
外科学 | 2354篇 |
综合类 | 240篇 |
一般理论 | 36篇 |
预防医学 | 3234篇 |
眼科学 | 298篇 |
药学 | 1498篇 |
中国医学 | 21篇 |
肿瘤学 | 1810篇 |
出版年
2024年 | 32篇 |
2023年 | 284篇 |
2022年 | 357篇 |
2021年 | 788篇 |
2020年 | 488篇 |
2019年 | 809篇 |
2018年 | 829篇 |
2017年 | 633篇 |
2016年 | 653篇 |
2015年 | 686篇 |
2014年 | 943篇 |
2013年 | 1354篇 |
2012年 | 2071篇 |
2011年 | 2202篇 |
2010年 | 1131篇 |
2009年 | 1010篇 |
2008年 | 1607篇 |
2007年 | 1700篇 |
2006年 | 1528篇 |
2005年 | 1329篇 |
2004年 | 1174篇 |
2003年 | 1059篇 |
2002年 | 928篇 |
2001年 | 127篇 |
2000年 | 73篇 |
1999年 | 96篇 |
1998年 | 159篇 |
1997年 | 87篇 |
1996年 | 74篇 |
1995年 | 75篇 |
1994年 | 57篇 |
1993年 | 42篇 |
1992年 | 37篇 |
1991年 | 32篇 |
1990年 | 34篇 |
1989年 | 27篇 |
1988年 | 37篇 |
1987年 | 35篇 |
1986年 | 35篇 |
1985年 | 31篇 |
1984年 | 30篇 |
1983年 | 25篇 |
1982年 | 22篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 22篇 |
1977年 | 11篇 |
1975年 | 9篇 |
1974年 | 13篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
John Lasekan Yong Choe Svyatoslav Dvoretskiy Amy Devitt Sue Zhang Amy Mackey Karyn Wulf Rachael Buck Christine Steele Michelle Johnson Geraldine Baggs 《Nutrients》2022,14(13)
Background: Five of the most abundant human milk oligosaccharides (HMOs) in human milk are 2′-fucosyllactose (2′-FL), 3-fucosyllactose (3-FL), lacto-N-tetraose (LNT), 3′-sialyllactose (3′-SL) and 6′-sialyllactose (6′-SL). Methods: A randomized, double-blind, controlled parallel feeding trial evaluated growth in healthy term infants fed a control milk-based formula (CF; n = 129), experimental milk-based formula (EF; n = 130) containing five HMOs (5.75 g/L; 2′-FL, 3-FL, LNT, 3′-SL and 6′-SL) or human milk (HM; n = 104). Results: No significant differences (all p ≥ 0.337, protocol evaluable cohort) were observed among the three groups for weight gain per day from 14 to 119 days (D) of age, irrespective of COVID-19 or combined non-COVID-19 and COVID-19 periods. There were no differences (p ≥ 0.05) among the three groups for gains in weight and length from D14 to D119. Compared to the CF group, the EF group had more stools that were soft, frequent and yellow and were similar to the HM group. Serious and non-serious adverse events were not different among groups, but more CF-fed infants were seen by health care professionals for illness from study entry to D56 (p = 0.044) and D84 (p = 0.028) compared to EF-fed infants. Conclusions: The study demonstrated that the EF containing five HMOs supported normal growth, gastrointestinal (GI) tolerance and safe use in healthy term infants. 相似文献
102.
Jonathan Blackman Hamish Duncan Morrison Katherine Lloyd Amy Gimson Luke Vikram Banerjee Sebastian Green Rebecca Cousins Sarah Rudd Sam Harding Elizabeth Coulthard 《Sleep》2022,45(7)
Study ObjectivesSleep abnormalities emerge early in dementia and may accelerate cognitive decline. Their accurate characterization may facilitate earlier clinical identification of dementia and allow for assessment of sleep intervention efficacy. This scoping review determines how sleep is currently measured and reported in Mild Cognitive Impairment (MCI) and early dementia, as a basis for future core outcome alignment.MethodsThis review follows the PRISMA Guidelines for Scoping Reviews. CINAHL, Embase, Medline, Psychinfo, and British Nursing Index databases were searched from inception—March 12, 2021. Included studies had participants diagnosed with MCI and early dementia and reported on sleep as a key objective/ outcome measure.ResultsNineteen thousand five hundred and ninety-six titles were returned following duplicate removal with 188 studies [N] included in final analysis. Sleep data was reported on 17 139 unique, diagnostically diverse participants (n). “Unspecified MCI” was the most common diagnosis amongst patients with MCI (n = 5003, 60.6%). Despite technological advances, sleep was measured most commonly by validated questionnaires (n = 12 586, N = 131). Fewer participants underwent polysomnography (PSG) (n = 3492, N = 88) and actigraphy (n = 3359, N = 38) with little adoption of non-PSG electroencephalograms (EEG) (n = 74, N = 3). Sleep outcome parameters were reported heterogeneously. 62/165 (37.6%) were described only once in the literature (33/60 (60%) in interventional studies). There was underrepresentation of circadian (n = 725, N = 25) and micro-architectural (n = 360, N = 12) sleep parameters.ConclusionsAlongside under-researched areas, there is a need for more detailed diagnostic characterization. Due to outcome heterogeneity, we advocate for international consensus on core sleep outcome parameters to support causal inference and comparison of therapeutic sleep interventions. 相似文献
103.
104.
105.
Brian L Sprague Amy Trentham-Dietz Curtis J Hedman Jue Wang Jocelyn DC Hemming John M Hampton Diana SM Buist Erin J Aiello Bowles Gale S Sisney Elizabeth S Burnside 《Breast cancer research : BCR》2013,15(3):R45
Introduction
Humans are widely exposed to estrogenically active phthalates, parabens, and phenols, raising concerns about potential effects on breast tissue and breast cancer risk. We sought to determine the association of circulating serum levels of these chemicals (reflecting recent exposure) with mammographic breast density (a marker of breast cancer risk).Methods
We recruited postmenopausal women aged 55 to 70 years from mammography clinics in Madison, Wisconsin (N = 264). Subjects completed a questionnaire and provided a blood sample that was analyzed for mono-ethyl phthalate, mono-butyl phthalate, mono-benzyl phthalate, butyl paraben, propyl paraben, octylphenol, nonylphenol, and bisphenol A (BPA). Percentage breast density was measured from mammograms by using a computer-assisted thresholding method.Results
Serum BPA was positively associated with mammographic breast density after adjusting for age, body mass index, and other potentially confounding factors. Mean percentage density was 12.6% (95% confidence interval (CI), 11.4 to 14.0) among the 193 women with nondetectable BPA levels, 13.7% (95% CI, 10.7 to 17.1) among the 35 women with detectable levels below the median (<0.55 ng/ml), and 17.6% (95% CI, 14.1 to 21.5) among the 34 women with detectable levels above the median (>0.55 ng/ml; Ptrend = 0.01). Percentage breast density was also elevated (18.2%; 95% CI, 13.4 to 23.7) among the 18 women with serum mono-ethyl phthalate above the median detected level (>3.77 ng/ml) compared with women with nondetectable BPA levels (13.1%; 95% CI, 11.9 to 14.3; Ptrend = 0.07). No other chemicals demonstrated associations with percentage breast density.Conclusions
Postmenopausal women with high serum levels of BPA and mono-ethyl phthalate had elevated breast density. Further investigation of the impact of BPA and mono-ethyl phthalate on breast cancer risk by using repeated serum measurements or other markers of xenoestrogen exposure are needed. 相似文献106.
OBJECTIVE: To determine the utility of screening for depression in pregnant women with human immunodeficiency virus (HIV) infection. STUDY DESIGN: Women with HIV infection who received prenatal care at an inner-city institution between March 2004 and March 2006 were offered the Beck Depression Inventory (BDI), a screening tool to detect depressive symptomatology. Scores >9 were considered positive. RESULTS: Of 51 subjects who participated, 53% had positive screening scores for depression. Of those whose scores were positive, 33% had no prior history of psychiatric illness. Those in whom HIV was diagnosed during pregnancy had higher mean and median BDI scores than those with HIV diagnosed before pregnancy (21.2 vs. 13.3 and 21 vs. 9.5, respectively; p = 0.049). Two factors were associated with positive screenings: history of psychiatric disease (p = 0.001) and history of substance abuse (p = 0.042). Patients with positive screenings first presented for prenatal care at a later gestational age and had fewer prenatal visits than those without evidence of depression (14.9 vs. 12.0, p = 0.035 and 9.2 vs. 11.3, p = 0.045). More than half (56%) who screened positive received psychological care during the prenatal period. CONCLUSION: Women with HIV infection should routinely be screened for depression during pregnancy. Those with positive screens should be offered formal psychological evaluation. 相似文献
107.
The role of apical vaginal support in the appearance of anterior and posterior vaginal prolapse 总被引:2,自引:0,他引:2
Lowder JL Park AJ Ellison R Ghetti C Moalli P Zyczynski H Weber AM 《Obstetrics and gynecology》2008,111(1):152-157
OBJECTIVE: To describe how simulated apical support affects the appearance of prolapse in the anterior and posterior vagina using a modification of the Pelvic Organ Prolapse Quantification (POP-Q) examination. METHODS: Women with prolapse stage II or greater were examined using the POP-Q. To simulate apical support, the posterior blade of a standard Graves speculum was positioned over the posterior vagina to support the vaginal apex while remeasuring points Aa and Ba and over the anterior vagina to support the apex while remeasuring points Ap and Bp. Change in anterior and posterior POP-Q points and prolapse stage with apical support were calculated. RESULTS: One hundred ninety-seven women were enrolled with mean age of 62+/-14 years, median parity of 2 (range 0-8), and mean body mass index of 28+/-5 kg/m(2). By standard POP-Q, 36% had stage II prolapse, 54% had stage III, and 10% had stage IV prolapse. With simulated apical support, point Ba changed to stage 0 or I in 55% of cases and point Bp changed to stage 0 or I in 30% (P<.001 for each point). Mean change for point Ba with apical support was 3.5+/-2.6 cm and point Bp was 1.9+/-2.9 cm (P<.001). CONCLUSION: When the POP-Q examination is performed with simulated apical support, the critical role of level I vaginal support on the position of the anterior and posterior vagina, particularly the anterior vagina, becomes apparent. LEVEL OF EVIDENCE: II. 相似文献
108.
OBJECTIVE: To evaluate the clinical efficacy and tolerability of topical gabapentin in the treatment of women with vulvodynia. METHODS: A retrospective study was designed to ascertain clinical responses to topical gabapentin. Patient demographic and medical characteristics, including present and prior treatment for vulvodynia, were routinely collected. The final outcome was defined by a comparison between pretreatment and posttreatment mean pain scores based on a discrete visual analog scale of 0 to 10. Categorical data were compared by Fisher exact test, continuous variables between groups by the Wilcoxon rank sum test, and mean change in pain score between pretreatment and posttreatment by paired Student t test. RESULTS: Between January 2001 and December 2006, 51 women with vulvodynia (19 or 37% with generalized vulvodynia, 32 or 63% with localized) were treated with 2% to 6% gabapentin. After a minimum of 8 weeks of therapy, the mean pain score among the 35 evaluable women was significantly reduced from 7.26 to 2.49 (mean change -4.77, 95% confidence interval -5.47 to -4.07). Overall, 28 of 35 (80%) demonstrated at least a 50% improvement in pain scores. Among patients with localized vulvodynia, sexual function improved in 17 of 20 with evaluable results (6 of 9 reinstituted vaginal intercourse, whereas all 11 patients experiencing decreased frequency of intercourse reported increased frequency after treatment). Discontinuations occurred in 7 of 50 (14%) treated. CONCLUSION: Topical gabapentin seems to be well-tolerated and associated with significant pain relief in women with vulvodynia. LEVEL OF EVIDENCE: III. 相似文献
109.
Most midwives are aware of the need to collect clinical practice data and of its usefulness in supporting the care they provide, which contributes to healthy outcomes for mothers and babies. For the individual midwife, there is more than one easily accessible, standardized data collection instrument from which to choose. However, despite these choices, in an American College of Nurse-Midwives (ACNM) Division of Research (DOR) survey on midwifery clinical data collection (N = 263), the majority of member respondents (n = 135; 51%) reported using a self-designed data collection tool, and more than one-third did not know of the ACNM Nurse-Midwifery Clinical Data Sets (NMCDS). On a larger scale, the midwifery profession is also in need of an organized and consistent approach to data collection for the purpose of capturing midwifery practice and outcomes in order to provide data to support legislation, practice, and policy changes. However, the profession currently lacks a single common midwifery practice database. In order to facilitate data aggregation that captures a larger view of midwifery practice at the local, regional, and national levels, it is imperative that all midwives collect relevant data that are uniform and standardized, and that the midwifery professional organizations move forward with the development of a common electronic database. This article describes currently available data collection tools as well as their best uses, applications to practice, and future directions. 相似文献
110.