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   170767篇
  免费   14382篇
  国内免费   5154篇
耳鼻咽喉   1847篇
儿科学   3470篇
妇产科学   1917篇
基础医学   18987篇
口腔科学   3468篇
临床医学   19110篇
内科学   30401篇
皮肤病学   2300篇
神经病学   12133篇
特种医学   6633篇
外国民族医学   30篇
外科学   22763篇
综合类   17060篇
现状与发展   18篇
一般理论   205篇
预防医学   13890篇
眼科学   3584篇
药学   14136篇
  112篇
中国医学   5990篇
肿瘤学   12249篇
  2024年   414篇
  2023年   1974篇
  2022年   4226篇
  2021年   6790篇
  2020年   4708篇
  2019年   5032篇
  2018年   5503篇
  2017年   4866篇
  2016年   4804篇
  2015年   6238篇
  2014年   8357篇
  2013年   9749篇
  2012年   14094篇
  2011年   14702篇
  2010年   9799篇
  2009年   8273篇
  2008年   11272篇
  2007年   10949篇
  2006年   10336篇
  2005年   9572篇
  2004年   7968篇
  2003年   7360篇
  2002年   6469篇
  2001年   2221篇
  2000年   1595篇
  1999年   1380篇
  1998年   1240篇
  1997年   1089篇
  1996年   830篇
  1995年   768篇
  1994年   612篇
  1993年   578篇
  1992年   462篇
  1991年   411篇
  1990年   379篇
  1989年   371篇
  1988年   336篇
  1987年   311篇
  1986年   326篇
  1985年   321篇
  1984年   373篇
  1983年   329篇
  1982年   351篇
  1981年   349篇
  1980年   270篇
  1979年   169篇
  1978年   203篇
  1977年   191篇
  1975年   140篇
  1974年   135篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
971.
Aging is associated with a progressive decline in skeletal muscle mass, strength and function (sarcopenia). We have investigated whether a mixture of algae oil (25%) and extra virgin olive oil (75%) could exert beneficial effects on sarcopenia. Young (3 months) and old (24 months) male Wistar rats were treated with vehicle or with the oil mixture (OM) (2.5 mL/kg) for 21 days. Aging decreased gastrocnemius weight, total protein, and myosin heavy chain mRNA. Treatment with the OM prevented these effects. Concomitantly, OM administration decreased the inflammatory state in muscle; it prevented the increase of pro-inflammatory interleukin-6 (IL-6) and the decrease in anti-inflammatory interleukin-10 (IL-10) in aged rats. The OM was not able to prevent aging-induced alterations in either the insulin-like growth factor I/protein kinase B (IGF-I/Akt) pathway or in the increased expression of atrogenes in the gastrocnemius. However, the OM prevented decreased autophagy activity (ratio protein 1A/1B-light chain 3 (LC3b) II/I) induced by aging and increased expression of factors related with muscle senescence such as histone deacetylase 4 (HDAC-4), myogenin, and IGF-I binding protein 5 (IGFBP-5). These data suggest that the beneficial effects of the OM on muscle can be secondary to its anti-inflammatory effect and to the normalization of HDAC-4 and myogenin levels, making this treatment an alternative therapeutic tool for sarcopenia.  相似文献   
972.
973.
Childhood obesity has become a major global health problem. Vitamin D deficiency and poor cardiorespiratory fitness are highly prevalent in children with overweight or obesity, but little is known about their relationships. In this study, we aimed to analyze the relationship between serum 25-hydroxyvitamin D (25(OH)D) and cardiorespiratory fitness parameters in prepubertal obese and overweight children. A cross-sectional design with a sample of 57 prepubertal children, aged 9–11 years, with overweight or obesity was used. The fasting concentration of 25(OH)D was analyzed with a chemiluminescent microparticle immunoassay. Fat and lean body masses were determined by using DXA. Maximal oxygen uptake (VO2max) was measured with the maximal treadmill test. A total of 68.4% of the sample had sufficient levels of 25(OH)D. As expected, their cardiorespiratory fitness was poor compared with that of normal-weight children, but 60% of the group exceeded the median obesity-specific reference values. No differences were found between the sexes for relative VO2max or 25(OH)D levels. Moreover, no correlations were found between 25(OH)D and body composition or cardiorespiratory parameters for sex or vitamin D groups. Vitamin D status seems not to be directly related to body composition or cardiorespiratory fitness in prepubertal overweight or obese children.  相似文献   
974.
The role of ADIPOQ gene variants on metabolic improvements after weight change secondary to different hypocaloric diets remained unclear. We evaluate the effect of rs3774261 of ADIPOQ gene polymorphism on biochemical improvements and weight change after high polyunsaturated fat hypocaloric diet with a Mediterranean dietary pattern for 12 weeks. A population of 361 obese subjects was enrolled in an intervention trial with a calorie restriction of 500 calories over the usual intake and 45.7% of carbohydrates, 34.4% of fats, and 19.9% of proteins. The percentages of different fats was; 21.8% of monounsaturated fats, 55.5% of saturated fats, and 22.7% of polyunsaturated fats. Before and after intervention, an anthropometric study, an evaluation of nutritional intake and a biochemical evaluation were realized. All patients lost weight regardless of genotype and diet used. After 12 weeks with a similar improvement in weight loss (AA vs. AG vs. GG); total cholesterol (delta: −28.1 ± 2.1 mg/dL vs. −14.2 ± 4.1 mg/dL vs. −11.0 ± 3.9 mg/dL; p = 0.02), LDL cholesterol (delta: −17.1 ± 2.1 mg/dL vs. −6.1 ± 1.9 mg/dL vs. −6.0 ± 2.3 mg/dL; p = 0.01), triglyceride levels (delta: −35.0 ± 3.6 mg/dL vs. 10.1 ± 3.2 mg/dL vs. −9.7 ± 3.1 mg/dL; p = 0.02), C reactive protein (CRP) (delta: −2.3 ± 0.1 mg/dL vs. −0.2 ± 0.1 mg/dL vs. −0.2 ± 0.1 mg/dL; p = 0.02), serum adiponectin (delta: 11.6 ± 2.9 ng/dL vs. 2.1 ± 1.3 ng/dL vs. 3.3 ± 1.1 ng/dL; p = 0.02) and adiponectin/leptin ratio (delta: 1.5 ± 0.1 ng/dL vs. 0.3 ± 0.2 ng/dL vs. 0.4 ± 0.3 ng/dL; p = 0.03), improved only in AA group. AA genotype of ADIPOQ variant (rs3774261) is related with a significant increase in serum levels of adiponectin and ratio adiponectin/leptin and decrease on lipid profile and C-reactive protein (CRP).  相似文献   
975.
The effects of exercise on nutrient digestion and absorption in the intestinal tract are not well understood. A few studies have reported that exercise training increases the expression of molecules involved in carbohydrate digestion and absorption. Exercise was also shown to increase the blood concentration of glucagon-like peptide-2 (GLP-2), which regulates carbohydrate digestion and absorption in the small intestine. Therefore, we investigated the effects of exercise on the expression of molecules involved in intestinal digestion and absorption, including GLP-2. Six-week-old male mice were divided into a sedentary (SED) and low-intensity exercise (LEx) group. LEx mice were required to run on a treadmill (12.5 m/min, 1 h), whereas SED mice rested. All mice were euthanized 1 h after exercise or rest, and plasma, jejunum, ileum, and colon samples were collected, followed by analysis via IHC, EIA, and immunoblotting. The levels of plasma GLP-2 and the jejunum expression of the GLP-2 receptor, sucrase-isomaltase (SI), and glucose transporter 2 (GLUT2) were higher in LEx mice. Thus, we showed that acute low-intensity exercise affects the expression of molecules involved in intestinal carbohydrate digestion and absorption via GLP-2. Our results suggest that exercise might be beneficial for small intestine function in individuals with intestinal frailty.  相似文献   
976.
目的分析云南省布鲁菌病(简称布病)流行特征,建立灰色GM(1,1)模型,预测云南省布病病情。方法收集中国疾病预防控制信息系统和云南省统计局2008-2018年云南省布病疫情数据和人口资料,分析布病流行病学特征(包括时间、地区、人群分布),并以灰色GM(1,1)模型进行建模,预测2019、2020年云南省布病发病率。结果2008-2018年云南省共报告布病病例1216例,年均发病率为0.2374/10万,呈逐年递增趋势(χ2趋势=843.34,P<0.01)。病例报告主要集中在3-9月份,占总病例数的69.41%(844/1216)。病例报告数居前5位的州市分别为红河州(289例)、曲靖市(264例)、昆明市(258例)、大理州(160例)、玉溪市(134例),占总病例数的90.87%(1105/1216)。职业以农民为主,占79.03%(961/1216)。建立灰色GM(1,1)模型预测2019、2020年云南省布病发病率分别为0.4876/10万和0.4817/10万。结论云南省布病发病较以往上升,应对重点地区、重点人群进行针对性防控,并对预测结果进行前瞻性评价,逐步完善云南省布病预测模型。  相似文献   
977.
Purpose

Smoking during pregnancy may be linked to other problematic prenatal health behaviors in women. We examined interrelationships among prenatal smoking, prenatal health behaviors and mental health. The objective of this study was to examine factors that may contribute to variations in prenatal health practices among women who smoke during pregnancy.

Methods

Birth mothers from an adoption study (N?=?912) were interviewed about prenatal smoking, health behaviors, and mental health symptoms at 5 months postpartum.

Results

One-quarter of participants (N?=?222) reported smoking 6 or more cigarettes daily for at least 1 trimester. For mothers who smoked more than 6 cigarettes daily, higher levels of antisocial behaviors (β?=????.14, p?=?.03) and depressive symptoms (β?=????.17, p?=?.03) were associated with less frequent prenatal folate use; antisocial behaviors and depressive symptoms were not associated for prenatal folate use among women who did not smoke more than 6 cigarettes daily. For mothers who did not smoke more than 6 cigarettes daily, more depressive symptoms were associated with fewer prenatal care visits (β?=?.12, p?=?.01). Antisocial behaviors and anxiety symptoms were not associated with prenatal care visits in either group of mothers.

Conclusions for Practice

Maternal antisocial behaviors and depressive symptoms during pregnancy may be markers for poorer adherence to recommendations for folate supplementation among women who smoke 6 or more cigarettes daily during pregnancy, independent of adequacy of prenatal care.

  相似文献   
978.
Maternal and Child Health Journal - Each year, 3% of infants in the Unites States (US) are born with congenital anomalies, including 3000 with neural tube defects. Multivitamins (MVIs) including...  相似文献   
979.
ObjectivesThe Depression Care for People with Cancer program (DCPC) is a cost-effective depression care model for UK patients with cancer. However, DCPC’s cost-effectiveness in the United States is unknown, particularly for patients with prostate cancer in the United States. This study evaluates the health and economic impact of providing DCPC to patients with prostate cancer.MethodsDCPC was compared with usual care in a mathematical model that simulates depression and its outcomes in a hypothetical cohort of US patients with prostate cancer. DCPC was modeled as a sequential combination of universal depression screening, post-screening evaluations, and first-line combination therapy. Primary outcomes were lifetime direct costs of depression care, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios. Secondary outcomes included life expectancy, number of depression-free months and lifetime depressive episodes, duration of depressive episodes, cumulative incidence of depression, lifetime depression diagnoses/misdiagnoses, and the cumulative incidence of maintenance therapy for depression. Sensitivity analyses were used to examine uncertainty.ResultsIn the base case, DCPC dominated usual care by offering 0.11 more QALYs for $2500 less per patient (from averted misdiagnoses). DCPC also offered 5 extra depression-free months, shorter depressive episodes, and a lower chance of maintenance therapy. DCPC’s trade-offs were a higher cumulative incidence of depression and more lifetime depressive episodes. Life expectancy was identical under usual care and DCPC. Sensitivity analyses indicate that DCPC was almost always preferable to usual care.ConclusionCompared with usual care, DCPC may offer more value to US patients with prostate cancer. DCPC should be considered for inclusion in prostate cancer survivorship care guidelines.  相似文献   
980.
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