收费全文 | 1925376篇 |
免费 | 153077篇 |
国内免费 | 5003篇 |
耳鼻咽喉 | 26374篇 |
儿科学 | 59970篇 |
妇产科学 | 54898篇 |
基础医学 | 272747篇 |
口腔科学 | 57692篇 |
临床医学 | 166967篇 |
内科学 | 380081篇 |
皮肤病学 | 41651篇 |
神经病学 | 153611篇 |
特种医学 | 76862篇 |
外国民族医学 | 546篇 |
外科学 | 296581篇 |
综合类 | 48302篇 |
现状与发展 | 4篇 |
一般理论 | 616篇 |
预防医学 | 137790篇 |
眼科学 | 44924篇 |
药学 | 147766篇 |
4篇 | |
中国医学 | 4913篇 |
肿瘤学 | 111157篇 |
2018年 | 18676篇 |
2016年 | 15976篇 |
2015年 | 18478篇 |
2014年 | 25590篇 |
2013年 | 37808篇 |
2012年 | 51222篇 |
2011年 | 53577篇 |
2010年 | 31810篇 |
2009年 | 30423篇 |
2008年 | 51133篇 |
2007年 | 54250篇 |
2006年 | 54878篇 |
2005年 | 52853篇 |
2004年 | 51778篇 |
2003年 | 49647篇 |
2002年 | 48520篇 |
2001年 | 98740篇 |
2000年 | 101828篇 |
1999年 | 85863篇 |
1998年 | 22255篇 |
1997年 | 20017篇 |
1996年 | 19543篇 |
1995年 | 18912篇 |
1994年 | 17665篇 |
1993年 | 16587篇 |
1992年 | 68777篇 |
1991年 | 66303篇 |
1990年 | 64512篇 |
1989年 | 62798篇 |
1988年 | 57940篇 |
1987年 | 56880篇 |
1986年 | 53864篇 |
1985年 | 51730篇 |
1984年 | 37959篇 |
1983年 | 32365篇 |
1982年 | 18436篇 |
1981年 | 16329篇 |
1980年 | 15296篇 |
1979年 | 35177篇 |
1978年 | 24005篇 |
1977年 | 20369篇 |
1976年 | 18683篇 |
1975年 | 19910篇 |
1974年 | 24167篇 |
1973年 | 23235篇 |
1972年 | 21416篇 |
1971年 | 20269篇 |
1970年 | 18591篇 |
1969年 | 17560篇 |
1968年 | 16019篇 |
Background
Current blunt cerebrovascular injury (BCVI) grading grossly differentiates injury characteristics such as luminal stenosis (LS) and aneurysmal disease. The effect of increasing degree of LS beyond the current BCVI grading scale on stroke formation is unknown.Study Design
BCVI over a 3-year period were retrospectively reviewed. To investigate influence of LS beyond the BCVI grading scale within aneurysmal and non-aneurysmal BCVI, grade 2 BCVI were subdivided into BCVI with ≥ 25% and ≤ 50% LS and BCVI with > 50% and ≤ 99% LS. Grade 3 BCVI were subdivided into BCVI with pseudoaneurysm (PSA) without LS and BCVI with PSA and LS. We hypothesized increased LS beyond the current BCVI grade distinctions would be associated with higher rates of stroke formation.Results
312 BCVI were included, of which 140 were carotid BCVI and 172 vertebral BCVI. Sixteen carotid BCVI underwent endovascular intervention (EI) and 19 suffered a stroke. In carotid BCVI stroke rates increased sequentially with BCVI grade except in grade 3. There was a stroke rate of 12% in grade 1 carotid BCVI, 18% in grade 2, 6% in grade 3, and 31% in grade 4. In subgroup analysis for grade 2 carotid BCVI, BCVI with > 50% and ≤ 99% LS had higher rates of stroke (22% vs. 15%, p?=?0.44) than BCVI with ≥ 25% and ≤ 50% LS. In subgroup analysis of grade 3 carotid BCVI, BCVI with PSA and LS had higher rates of stroke (9% vs. 4%, p?=?0.48) than BCVI with PSA without LS. Higher rates of EI in grade 2 carotid BCVI with > 50% and ≤ 99% LS (22% vs. 5%, p?=?0.14) and grade 3 carotid BCVI with PSA and LS (35% vs. 4%, p?=?0.01) were noted in subgroup analysis.Conclusion
Higher percentage LS beyond the currently used BCVI grading scale has a non-significantly increased rate of stroke in both aneurysmal and non-aneurysmal BCVI. Grade 3 BCVI with PSA and LS seems to be a high-risk subgroup. Use of EI confounds modern measurement of stroke risk in higher LS BCVI. 相似文献Background
The Lancet Commission on Global Surgery highlighted global surgical need but offered little insight into the specific surgical challenges of children in low-resource settings. Efforts to strengthen the quality of global pediatric surgical care have resulted in a proliferation of partnerships between low-and middle-income countries (LMICs) and high-income countries (HICs). Standardized tools able to reliably measure gaps in delivery and quality of care are important aids for these partnerships. We undertook a systematic review (SR) of capacity assessment tools (CATs) focused on needs assessment in pediatric surgery.Methods
A comprehensive search strategy of multiple electronic databases was conducted per PRISMA guidelines without linguistic or temporal restrictions. CATs were selected according to pre-defined inclusion criteria. Articles were assessed by two independent reviewers. Methodological quality of studies was appraised using the COSMIN checklist with 4-point scale.Results
The search strategy generated 16,641 original publications, of which three CATs were deemed eligible. Eligible tools were either excessively detailed or oversimplified. None used weighted scores to identify finer granularity between institutions. No CATs comprehensively included measures of resources, outcomes, accessibility/impact and training.Discussion
The results of this study identify the need for a CAT capable of objectively measuring key aspects of surgical capacity and performance in a weighted tool designed for pediatric surgical centers in LMICs.Type of Study
Systematic Review.Level of Evidence
II. 相似文献Methods: Data from 1392 girls, aged 9 to 10 at baseline and followed for 10?years, in the National Heart, Lung, and Blood Institute’s National Growth and Health Study were used to examine the association between usual egg intake alone and in combination with other healthy lifestyle factors and late adolescent lipid levels, fasting glucose, and insulin resistance, measured as homeostasis model assessment of insulin resistance (HOMA-IR). Diet was assessed using 3-day food records during eight examination cycles. Girls were classified according to usual weekly egg intake, ages 9–17?years:?<1 egg/wk (n?=?361), 1 to <3 eggs/wk (n?=?703), and ≥3 eggs/wk (n?=?328). Analysis of covariance modeling was used to control for confounding by other behavioral and biological risk factors.
Results: Girls with low, moderate, and high egg intakes had adjusted low-density lipoprotein cholesterol levels of 99.7, 98.8, and 95.5 mg/dL, respectively (p?=?0.0778). In combination with higher intakes of fiber, dairy, or fruits and vegetables, these beneficial effects were stronger and statistically significant. There was no evidence that ≥3 eggs/wk had an adverse effect on lipids, glucose, or HOMA-IR. More active girls who consumed ≥3 eggs/wk had the lowest levels of insulin resistance.
Conclusion: These results suggest that eggs may be included as part of a healthy adolescent diet without adverse effects on glucose, lipid levels, or insulin resistance. 相似文献