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   6513篇
  免费   447篇
  国内免费   75篇
耳鼻咽喉   60篇
儿科学   244篇
妇产科学   319篇
基础医学   798篇
口腔科学   192篇
临床医学   772篇
内科学   1310篇
皮肤病学   113篇
神经病学   384篇
特种医学   313篇
外科学   831篇
综合类   186篇
一般理论   2篇
预防医学   286篇
眼科学   201篇
药学   538篇
中国医学   88篇
肿瘤学   398篇
  2023年   48篇
  2022年   66篇
  2021年   155篇
  2020年   88篇
  2019年   149篇
  2018年   194篇
  2017年   122篇
  2016年   133篇
  2015年   195篇
  2014年   215篇
  2013年   317篇
  2012年   485篇
  2011年   446篇
  2010年   267篇
  2009年   256篇
  2008年   371篇
  2007年   350篇
  2006年   332篇
  2005年   299篇
  2004年   260篇
  2003年   223篇
  2002年   188篇
  2001年   180篇
  2000年   203篇
  1999年   128篇
  1998年   83篇
  1997年   96篇
  1996年   79篇
  1995年   59篇
  1994年   64篇
  1993年   45篇
  1992年   115篇
  1991年   94篇
  1990年   91篇
  1989年   88篇
  1988年   87篇
  1987年   60篇
  1986年   56篇
  1985年   52篇
  1984年   39篇
  1983年   24篇
  1982年   30篇
  1981年   18篇
  1980年   20篇
  1979年   22篇
  1978年   21篇
  1977年   21篇
  1976年   13篇
  1971年   12篇
  1970年   12篇
排序方式: 共有7035条查询结果,搜索用时 15 毫秒
91.
Several studies have reported the therapeutic use of caffeoylquinic acid (CQA) derivatives in the management of hyperglycemia. This study used a simulated in vitro gastrointestinal digestion model to assess the inhibitory effects of CQA derivatives-rich sweet potato leaf extract (SPLE) and a commercially produced green coffee bean extract (GCBE), each with total polyphenols contents of 452 mg g−1 and 278 mg g−1, respectively, against starch digestion. The changes in the amounts of total polyphenols and total CQA derivatives during in vitro gastrointestinal digestion were also examined. The results indicated that both extracts contained substantial levels of CQA derivatives (136 mg g−1 and 83.5 mg g−1 of extract for SPLE and GCBE, respectively). The amounts of total polyphenols and total CQA derivatives in 20 mg of SPLE and GCBE samples decreased from 9.04 mg to 0.58 mg and from 5.56 mg to 0.58 mg, and from 2.72 mg to 0.16 mg and from 1.67 mg to 0.10 mg, respectively, following in vitro gastrointestinal digestion and subsequent dialysis. When SPLE and GCBE were accompanied with starch for in vitro digestion test, they both exhibited inhibitory effect against starch digestion during simulated intestinal digestion, with estimated half maximal inhibitory concentration (IC50) values of 4.91 mg and 6.06 mg polyphenols, respectively. The amount of glucose permeated through dialysis membrane also decreased significantly in comparison with the extract-negative control. Thus, both SPLE and GCBE were capable of modulating the release of glucose from starch digestion in simulated intestinal tract. The observed inhibitory effects against glucose release were presumably due in part to the presence of CQA derivatives in the tested extracts. The SPLE had higher inhibitory effect against in vitro starch digestion than the commercially prepared reference GCBE. Therefore, the SPLE might be used to manage hyperglycemia over the long term.  相似文献   
92.
Oral cancer is one of the leading causes of cancer death, which are mostly preceded by oral potentially malignant disorders (OPMDs). Taiwanese government launched a free oral cancer screening program. The aim of this study was to analyze the malignant transformation rate of OPMDs.This study was based on national-wide oral screening databases. 3,362,232 people were enrolled. Patients clinically diagnosed with leukoplakia, erythroplakia, oral submucosal fibrosis (OSF), oral verrucous hyperplasia (OVH), and oral lichen planus (OLP), from 2010 to 2013, were identified. We followed up OPMD patients in cancer registry databases to analyze the malignant transformation rate.The malignant transformation rates from the highest to the lowest were: OVH > OSF > erythroplakia > OLP > leukoplakia. The malignant transformation rate was 24.55, 12.76, 9.75, 4.23, and 0.60 per 1000 person-years in the OVH, OSF, erythroplakia, leukoplakia, and comparison cohort. The hazard ratio was 8.19 times higher in the OPMD group compared with comparison cohort group, after age and habit adjustment. Female patients with OPMDs had a high risk of malignant transformation.Nationwide screening is very important for early diagnosis. OVH had the highest malignant transformation possibility. Female OPMD patients are a rare but have a relatively high malignant transformation rate.  相似文献   
93.
94.
Intravenous picrotoxin injection has been established as a model of producing arrhythmias, mainly through enhanced central sympathetic outflow. The effects of calcium-channel blockers, and a beta-blocker on these arrhythmias were tested in chloralose-anesthetized cats. Picrotoxin (10 mg/kg, i.v.) produced mostly ventricular, sometimes supraventricular tachycardias and ectopic beats, as well as a marked elevation of arterial blood pressure. Nifedipine at the doses of 2 micrograms/kg (i.v. or i.c.) and 5 micrograms/kg (i.v.) transiently suppressed the arrhythmias in some of the cats tested. With the dose of 10 micrograms/kg (i.v.), it promptly and consistently abolished the arrhythmias without recurrence and significantly reduced the blood pressure (-62 +/- 8/-59 +/- 8 mmHg, delta systolic pressure/delta diastolic pressure, p less than 0.001, n = 9). A similar degree of blood pressure reduction (-69 +/- 8/-67 +/- 7 mmHg, n = 6) after sodium nitroprusside (4-5 mg/kg, i.v.) injection abolished the arrhythmias in 4 of 6 cats; however, there was marked ECG evidence of myocardial ischemia in 3 cats. Verapamil (50 micrograms/kg, i.v.) transiently abolished the arrhythmias and significantly decreased the blood pressure (7/7 cats), whereas a larger dose (150 micrograms/kg) had a persistent effect (2/4 cats). Propranolol at a dose of 240 micrograms/kg also consistently abolished the arrhythmias without recurrence in all 4 cats. We conclude that nifedipine, verapamil and propranolol are effective in the treatment of picrotoxin-induced arrhythmias. This result indicates that calcium-channel blockers or beta-blockers may be clinically effective in the treatment or prevention of arrhythmias caused by intracranial lesions with enhanced sympathetic outflow.  相似文献   
95.
96.
Chu  Yu-Ju  Jeng  Wen-Juei  Pan  Mei-Hung  Hu  Hui-Han  Luo  Wen-Sheng  Su  Chien-Yu  Chiang  Chen-Tse  Jen  Chin-Lan  Chen  Chien-Jen  Yang  Hwai-I 《Journal of gastroenterology》2022,57(6):423-432
Journal of Gastroenterology - In chronic hepatitis B virus (HBV) infection, earlier seroclearance of hepatitis B e antigen (HBeAg) is associated with more favorable outcomes. Soluble programmed...  相似文献   
97.
To further clarify the association of HLA DR alleles with type 1 diabetes mellitus and the influence of age-onset and gender on type 1 diabetes, we investigated HLA-DR in 76 child onset Chinese (36 males) type 1 diabetes patients and 154 normal controls by using PCR-SSP (sequence specific primer). The mean age of onset of diabetes patients was 8.43 +/- 3.96 year-old. Our results revealed that the frequencies of DR3, DR4 and DR9 in diabetes patients were significantly higher than those in control group (all P < 0.01). The susceptible alleles were DR3, DR4, DR9, with relative risks of 8.25, 2.57 and 2.67, respectively. The protective alleles to type 1 diabetes were DR 2, DR8, DR11 and DR12 with relative risk of 0.24, 0.15, 0.16 and 0.39, respectively. There were no significant differences between the frequencies of HLA DR 3, DR4, DR9, DR3/4, DR3/9 and DR4/9 in male and female diabetic children. We divided the diabetes patients into three groups according to their age of onset (1-5 years old, 6-10 years old and 11-17 years old). There was a trend that the frequencies of DR9 decreased with the increase of age at onset, but there was no significant difference of DR3, DR4, DR9, DR3/4, DR3/9 and DR4/9 frequencies between diabetes children with age onset 0-10 years and 11-17 years. As to the influence of gender on the HLA genotypes, the frequency of DR3/4 decreased with the increase of age at onset for male patients and the frequency of DR3/4 increased with the increase of age at onset for female patients.  相似文献   
98.
All tobacco smokers should be identified and provided with a smoking cessation intervention (SCI) during tuberculosis (TB) treatment. To ensure that this occurs, the intervention process should be recorded and monitored. Monitoring is the best guarantee that care is standardised and offered equitably to all patients. It allows for evaluation of processes and outcomes so that population needs can be identified and appropriate techniques added or updated. In this article we propose steps for brief intervention as a part of the monitoring process, using model forms and suggested procedures for filling them in. The suggested forms are a modified TB treatment card that includes information about tobacco use, an SCI patient card to be added to the patient's TB treatment folder, SCI registers and SCI quarterly report forms and a tobacco use questionnaire for evaluation of services.  相似文献   
99.
100.
Mentorship is considered to play a paramount role in empowering nursing students to recieve superlative benefit from clinical placement. Although the new standards for student supervision and assessment approved by the Nursing and Midwifery Council in 2018 seemed to lead to the disillusionment of mentorship, they support clinical education and devotion to nursing students' clinical learning globally. The aim of this synthesis was to review and explore the experiences of mentorship of preregistration nursing students and nurses. A systematic search of databases was performed for qualitative studies published in English from 2000 to 2018. Eleven qualitative studies were selected, from which three analytical themes emerged: mentors' capabilities and readiness for preregistration nursing student mentorship, humanistic approach as foundation to the effectiveness of preregistration nursing student mentorship, and the collaboration of stakeholders in health care and educational settings to enhance preregistration nursing student mentorship. A thematic framework of mentorship in preregistration nursing education was introduced. The thematic synthesis sheds light on how to improve a formal system of mentorship and clinical supervision for nursing education.  相似文献   
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