全文获取类型
收费全文 | 1416190篇 |
免费 | 116519篇 |
国内免费 | 3343篇 |
专业分类
耳鼻咽喉 | 18434篇 |
儿科学 | 46843篇 |
妇产科学 | 41192篇 |
基础医学 | 201714篇 |
口腔科学 | 37961篇 |
临床医学 | 126904篇 |
内科学 | 285707篇 |
皮肤病学 | 33451篇 |
神经病学 | 117612篇 |
特种医学 | 54076篇 |
外国民族医学 | 464篇 |
外科学 | 211685篇 |
综合类 | 32999篇 |
现状与发展 | 3篇 |
一般理论 | 515篇 |
预防医学 | 110702篇 |
眼科学 | 31622篇 |
药学 | 99170篇 |
1篇 | |
中国医学 | 3351篇 |
肿瘤学 | 81646篇 |
出版年
2021年 | 10928篇 |
2019年 | 11768篇 |
2018年 | 16695篇 |
2017年 | 12757篇 |
2016年 | 14347篇 |
2015年 | 16095篇 |
2014年 | 22741篇 |
2013年 | 33651篇 |
2012年 | 45709篇 |
2011年 | 48262篇 |
2010年 | 28350篇 |
2009年 | 27252篇 |
2008年 | 44647篇 |
2007年 | 47206篇 |
2006年 | 47740篇 |
2005年 | 46232篇 |
2004年 | 44096篇 |
2003年 | 42001篇 |
2002年 | 40466篇 |
2001年 | 73255篇 |
2000年 | 74749篇 |
1999年 | 61766篇 |
1998年 | 17092篇 |
1997年 | 15498篇 |
1996年 | 15657篇 |
1995年 | 14861篇 |
1994年 | 13466篇 |
1993年 | 12656篇 |
1992年 | 46020篇 |
1991年 | 43649篇 |
1990年 | 41655篇 |
1989年 | 39718篇 |
1988年 | 36341篇 |
1987年 | 35524篇 |
1986年 | 33019篇 |
1985年 | 31442篇 |
1984年 | 23946篇 |
1983年 | 20120篇 |
1982年 | 12288篇 |
1981年 | 10849篇 |
1979年 | 20788篇 |
1978年 | 14640篇 |
1977年 | 12141篇 |
1976年 | 11437篇 |
1975年 | 11678篇 |
1974年 | 14055篇 |
1973年 | 13609篇 |
1972年 | 12708篇 |
1971年 | 11520篇 |
1970年 | 10947篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
181.
182.
Imre W.K. Kouw Bart B.L. Groen Joey S.J. Smeets Irene Fleur Kramer Janneau M.X. van Kranenburg Rachél Nilwik Jan A.P. Geurts René H.M. ten Broeke Martijn Poeze Luc J.C. van Loon Lex B. Verdijk 《Journal of the American Medical Directors Association》2019,20(1):35-42
Objectives
Short successive periods of skeletal muscle disuse have been suggested to substantially contribute to the observed loss of skeletal muscle mass over the life span. Hospitalization of older individuals due to acute illness, injury, or major surgery generally results in a mean hospital stay of 5 to 7 days, during which the level of physical activity is strongly reduced. We hypothesized that hospitalization following elective total hip arthroplasty is accompanied by substantial leg muscle atrophy in older men and women.Design and participants
Twenty-six older patients (75 ± 1 years) undergoing elective total hip arthroplasty participated in this observational study.Measurements
On hospital admission and on the day of discharge, computed tomographic (CT) scans were performed to assess muscle cross-sectional area (CSA) of both legs. During surgery and on the day of hospital discharge, a skeletal muscle biopsy was taken from the m. vastus lateralis of the operated leg to assess muscle fiber type–specific CSA.Results
An average of 5.6 ± 0.3 days of hospitalization resulted in a significant decline in quadriceps (?3.4% ± 1.0%) and thigh muscle CSA (?4.2% ± 1.1%) in the nonoperated leg (P < .05). Edema resulted in a 10.3% ± 1.7% increase in leg CSA in the operated leg (P < .05). At hospital admission, muscle fiber CSA was smaller in the type II vs type I fibers (3326 ± 253 μm2 vs 4075 ± 279 μm2, respectively; P < .05). During hospitalization, type I and II muscle fiber CSA tended to increase, likely due to edema in the operated leg (P = .10).Conclusions
Six days of hospitalization following elective total hip arthroplasty leads to substantial leg muscle atrophy in older patients. Effective intervention strategies are warranted to prevent the loss of muscle mass induced by short periods of muscle disuse during hospitalization. 相似文献183.
Astrid Ruiz-Marg in Berenice M Rom n-Calleja Paulina Moreno-Guill n Jos A Gonz lez-Regueiro Deyanira K sulas-Delint Alejandro Campos-Murgu a Nayelli C Flores-Garc a Ricardo Ulises Mac as-Rodr guez 《World journal of gastrointestinal oncology》2021,13(10):1440-1452
Hepatocellular carcinoma (HCC) is the most frequent primary liver cancer and presents together with cirrhosis in most cases. In addition to commonly recognized risk factors for HCC development, such as hepatitis B virus/hepatitis C virus infection, age and alcohol/tobacco consumption, there are nutritional risk factors also related to HCC development including high intake of saturated fats derived from red meat, type of cooking (generation of heterocyclic amines) and contamination of foods with aflatoxins. On the contrary, protective nutritional factors include diets rich in fiber, fruits and vegetables, n-3 polyunsaturated fatty acids and coffee. While the patient is being evaluated for staging and treatment of HCC, special attention should be paid to nutritional support, including proper nutritional assessment and therapy by a multidisciplinary team. It must be considered that these patients usually develop HCC on top of long-lasting cirrhosis, and therefore they could present with severe malnutrition. Cirrhosis-related complications should be properly addressed and considered for nutritional care. In addition to traditional methods, functional testing, phase angle and computed tomography scan derived skeletal muscle index-L3 are among the most useful tools for nutritional assessment. Nutritional therapy should be centered on providing enough energy and protein to manage the increased requirements of both cirrhosis and cancer. Supplementation with branched-chain amino acids is also recommended as it improves response to treatment, nutritional status and survival, and finally physical exercise must be encouraged and adapted to individual needs. 相似文献
184.
185.
Harinakshi Sanikini David C. Muller Marisa Sophiea Sabina Rinaldi Antonio Agudo Eric J. Duell Elisabete Weiderpass Kim Overvad Anne Tjønneland Jytte Halkjær Marie-Christine Boutron-Ruault Franck Carbonnel Iris Cervenka Heiner Boeing Rudolf Kaaks Tilman Kühn Antonia Trichopoulou Georgia Martimianaki Anna Karakatsani Valeria Pala Domenico Palli Amalia Mattiello Rosario Tumino Carlotta Sacerdote Guri Skeie Charlotta Rylander María-Dolores Chirlaque López Maria-Jose Sánchez Eva Ardanaz Sara Regnér Tanja Stocks Bas Bueno-de-Mesquita Roel C.H. Vermeulen Dagfinn Aune Tammy Y.N. Tong Nathalie Kliemann Neil Murphy Marc Chadeau-Hyam Marc J. Gunter Amanda J. Cross 《International journal of cancer. Journal international du cancer》2020,146(4):929-942
Obesity has been associated with upper gastrointestinal cancers; however, there are limited prospective data on associations by subtype/subsite. Obesity can impact hormonal factors, which have been hypothesized to play a role in these cancers. We investigated anthropometric and reproductive factors in relation to esophageal and gastric cancer by subtype and subsite for 476,160 participants from the European Prospective Investigation into Cancer and Nutrition cohort. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox models. During a mean follow-up of 14 years, 220 esophageal adenocarcinomas (EA), 195 esophageal squamous cell carcinomas, 243 gastric cardia (GC) and 373 gastric noncardia (GNC) cancers were diagnosed. Body mass index (BMI) was associated with EA in men (BMI ≥30 vs. 18.5–25 kg/m2: HR = 1.94, 95% CI: 1.25–3.03) and women (HR = 2.66, 95% CI: 1.15–6.19); however, adjustment for waist-to-hip ratio (WHR) attenuated these associations. After mutual adjustment for BMI and HC, respectively, WHR and waist circumference (WC) were associated with EA in men (HR = 3.47, 95% CI: 1.99–6.06 for WHR >0.96 vs. <0.91; HR = 2.67, 95% CI: 1.52–4.72 for WC >98 vs. <90 cm) and women (HR = 4.40, 95% CI: 1.35–14.33 for WHR >0.82 vs. <0.76; HR = 5.67, 95% CI: 1.76–18.26 for WC >84 vs. <74 cm). WHR was also positively associated with GC in women, and WC was positively associated with GC in men. Inverse associations were observed between parity and EA (HR = 0.38, 95% CI: 0.14–0.99; >2 vs. 0) and age at first pregnancy and GNC (HR = 0.54, 95% CI: 0.32–0.91; >26 vs. <22 years); whereas bilateral ovariectomy was positively associated with GNC (HR = 1.87, 95% CI: 1.04–3.36). These findings support a role for hormonal pathways in upper gastrointestinal cancers. 相似文献
186.
187.
Michael A. Gibney David Fitz-Patrick David C. Klonoff Shahista Whooley Betty Lu Wen Yue 《Current medical research and opinion》2020,36(10):1591-1600
Abstract
Objective
Two similarly designed studies compared user experiences with a second-generation extra-thin-wall, 5-bevel 32?G?×?4?mm pen needle (PN) with redesigned hub versus four thinner commercially available PNs. 相似文献188.
189.
Pediatric dermatology is one of the smallest subspecialties, and expanding the availability of care is of great interest. Teledermatology has been proposed as a way to expand access and improve care delivery, but no current assessment of pediatric teledermatology exists. The objective of the current study was to assess usage and perspectives on pediatric teledermatology. Surveys were distributed electronically to all 226 board‐certified U.S. pediatric dermatologists; 44% (100/226) responded. Nearly all respondents (89%) have experience with teledermatology. Formal teledermatology reimbursement success rates have increased to 35%. Respondents were positive about teledermatology's present and future prospects, and 41% want to use teledermatology more often, although they viewed teledermatology as somewhat inferior to in‐person care regarding accuracy of diagnosis and appropriation of management plans. Significant differences were found between formal teledermatology users and nonusers in salary structure, practice environment, sex, and region. Substantial increases in pediatric teledermatology have occurred in the last 5 to 10 years, and there remains cause for optimism for teledermatology's future. Concerns about diagnostic confidence and care quality indicate that teledermatology may be best for care of patients with characteristic clinical presentations or management of patients with established diagnoses. 相似文献
190.