全文获取类型
收费全文 | 4312篇 |
免费 | 338篇 |
国内免费 | 31篇 |
专业分类
耳鼻咽喉 | 42篇 |
儿科学 | 114篇 |
妇产科学 | 105篇 |
基础医学 | 503篇 |
口腔科学 | 312篇 |
临床医学 | 555篇 |
内科学 | 1013篇 |
皮肤病学 | 32篇 |
神经病学 | 261篇 |
特种医学 | 186篇 |
外科学 | 540篇 |
综合类 | 76篇 |
一般理论 | 2篇 |
预防医学 | 385篇 |
眼科学 | 67篇 |
药学 | 355篇 |
中国医学 | 5篇 |
肿瘤学 | 128篇 |
出版年
2021年 | 56篇 |
2020年 | 28篇 |
2019年 | 53篇 |
2018年 | 63篇 |
2017年 | 48篇 |
2016年 | 51篇 |
2015年 | 56篇 |
2014年 | 127篇 |
2013年 | 137篇 |
2012年 | 204篇 |
2011年 | 197篇 |
2010年 | 93篇 |
2009年 | 109篇 |
2008年 | 202篇 |
2007年 | 205篇 |
2006年 | 149篇 |
2005年 | 184篇 |
2004年 | 217篇 |
2003年 | 188篇 |
2002年 | 162篇 |
2001年 | 153篇 |
2000年 | 152篇 |
1999年 | 132篇 |
1998年 | 63篇 |
1997年 | 56篇 |
1996年 | 47篇 |
1995年 | 53篇 |
1994年 | 48篇 |
1993年 | 45篇 |
1992年 | 90篇 |
1991年 | 84篇 |
1990年 | 97篇 |
1989年 | 86篇 |
1988年 | 87篇 |
1987年 | 85篇 |
1986年 | 77篇 |
1985年 | 74篇 |
1984年 | 76篇 |
1983年 | 63篇 |
1982年 | 30篇 |
1981年 | 30篇 |
1980年 | 35篇 |
1979年 | 39篇 |
1978年 | 35篇 |
1977年 | 34篇 |
1976年 | 34篇 |
1974年 | 35篇 |
1971年 | 28篇 |
1968年 | 27篇 |
1966年 | 26篇 |
排序方式: 共有4681条查询结果,搜索用时 0 毫秒
101.
102.
Background Acute myocardial infarction (AMI) is a common cause of heart failure (HF), which can develop soon after AMI and may persist or resolve or develop late. HF after an MI is a major source of mortality. The cumulative incidence, prevalence and resolution of HF after MI in different age groups are poorly described. This study describes the natural history of HF after AMI according to age. Methods Patients with AMI during 1998 were identified from hospital records. HF was defined as treatment of symptoms and signs of HF with loop diuretics and was considered to have resolved if loop diuretic therapy could be stopped without recurrence of symptoms. Patients were cate- gorised into those aged 〈 65 years, 65-75 years, and 〉 75 years. Results Of 896 patients, 311,297 and 288 were aged 〈 65, 65-75 and 〉75 years and of whom 24%, 57% and 82% had died respectively by December 2005. Of these deaths, 24 (8%), 68 (23%) and 107 (37%) oc- curred during the index admission, many associated with acute HF. A further 37 (12%), 63 (21%) and 82 (29%) developed HF that persisted until discharge, of whom 15, 44 and 62 subsequently died. After discharge, 53 (24%), 55 (40%) and 37 (47%) patients developed I-IF for the first time, of whom 26%, 62% and 76% subsequently died. Death was preceded by the development of HF in 35 (70%), 93 (91%) and 107 (85%) in aged 〈 65 years, 65-75 years and 〉75 years, respectively. Conclusions The risk of developing HF and of dying after an MI in- creases progressively with age. Regardless of age, most deaths after a MI are preceded by the development of HF. 相似文献
103.
104.
Salivary cortisol has been recently used to assess welfare of captive and free-ranging animals. However, rhythms of cortisol secretion may vary annually and thus, it is necessary to take into account these rhythms when evaluating the physiological significance of fluctuations of this hormone throughout the year as stress indicator in animals. Here, we analyze monthly differences in cortisol secretion in Asian elephants (Elephas maximus) during a year. Saliva samples of eight adult female Asian elephants were collected and analyzed using Radioimmunoassay. Results revealed an overall seasonal pattern of salivary cortisol secretion and significant differences in cortisol concentration among months were found. Overall, the highest cortisol levels were recorded in October, and then decreased until reaching the lowest concentration in April. However, some individual variations were found respect this annual overall trend. The occurrence of this annual pattern of cortisol secretion should be taken into account when using cortisol as a tool to assess animal welfare in captive animal at zoological parks, as well as it opens new questions to further analyze this pattern and its variations, as well as the endogenous mechanisms controlling it. 相似文献
105.
Arterial dysfunction (AD) in type 2 diabetes mellitus (T2DM) predicts cardiovascular events. The objective was to investigate the prevalence and predictors of AD in statin-treated T2DM patients. We measured flow-mediated (FMD) and nitrate-mediated (NMD) brachial artery dilatation in 86 statin-treated T2DM patients. Patients were classified into 2 groups: normal arterial function (FMD ≥3.7% with NMD ≥11.9%) or AD (FMD <3.7% with or without NMD <11.9%). Endothelial dysfunction without smooth muscle cell dysfunction (ED) was defined as FMD less than 3.7% with NMD of at least 11.9%, and endothelial dysfunction with smooth muscle cell dysfunction (ED/SMD) was defined as FMD less than 3.7% with NMD less than 11.9%. Predictors of arterial function were investigated using linear and logistic regression methods. The prevalence of AD was 33.7% (23.2% with ED and 10.5% with ED/SMD). In multivariate linear regression, history of hypertension (P < .01), statin dose (P < .05), and estimated glomerular filtration rate (eGFR) (P = .02) were significant predictors of FMD. Sex (P < .01) and creatinine (P = .03) or eGFR (P = .02) predicted NMD. In multivariate logistic regression, the independent predictors of AD were history of hypertension (odds ratio [OR], 8.79; 95% confidence interval, 2.14-36.12; P < .01), age (OR, 1.08; 1.01-1.17; P = .03), and statin dose (OR, 0.33; 0.12-0.87; P = .02). A history of hypertension (OR, 8.99; 1.87-43.26; P < .01) was the sole independent predictor of ED; eGFR (OR, 0.01; 0.00-0.26; P < .01) independently predicted ED/SMD. Our data suggest that one third of statin-treated diabetic patients have residual AD, mainly due to ED alone. Earlier identification and treatment of hypertension and renal impairment may improve AD and further decrease cardiovascular risk in such patients. 相似文献
106.
Familial hypercholesterolemia (FH) is a dominantly inherited disorder principally due to mutations in the low-density lipoprotein (LDL) receptor that classically cause markedly elevated plasma LDL cholesterol concentrations and premature coronary heart disease (CHD). However, elevated plasma LDL cholesterol alone does not fully account for the increase or variation in risk of CHD. We propose a hypothetical model for the role of postprandial dyslipoproteinemia based on the overproduction and decreased catabolism of triglyceride-rich lipoproteins, which may be a consequence of LDL receptor deficiency. Expression of postprandial dyslipoproteinemia in FH may also depend on the type of pathogenic gene variants and on coexistent conditions, particularly obesity and insulin resistance. Further research is required to investigate our model proposed and to test whether treating postprandial dyslipoproteinemia decreases CHD risk in FH incremental to standard therapy. 相似文献
107.
J Wang S Suri DJ Watts 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(36):14363-14368
The natural tendency for humans to make and break relationships is thought to facilitate the emergence of cooperation. In particular, allowing conditional cooperators to choose with whom they interact is believed to reinforce the rewards accruing to mutual cooperation while simultaneously excluding defectors. Here we report on a series of human subjects experiments in which groups of 24 participants played an iterated prisoner's dilemma game where, critically, they were also allowed to propose and delete links to players of their own choosing at some variable rate. Over a wide variety of parameter settings and initial conditions, we found that dynamic partner updating significantly increased the level of cooperation, the average payoffs to players, and the assortativity between cooperators. Even relatively slow update rates were sufficient to produce large effects, while subsequent increases to the update rate had progressively smaller, but still positive, effects. For standard prisoner's dilemma payoffs, we also found that assortativity resulted predominantly from cooperators avoiding defectors, not by severing ties with defecting partners, and that cooperation correspondingly suffered. Finally, by modifying the payoffs to satisfy two novel conditions, we found that cooperators did punish defectors by severing ties, leading to higher levels of cooperation that persisted for longer. 相似文献
108.
109.
110.
Talia M. Muram David A. Stevenson Sarah Watts‐Justice David H. Viskochil John C. Carey Rong Mao Brian Jackson 《American journal of medical genetics. Part A》2013,161(3):467-472
Neurofibromatosis type 1 (NF1) is a clinically diagnosed autosomal dominant disorder requiring routine clinical management, particularly during the pediatric years. An overlapping disorder, Legius syndrome, at times is clinically indistinguishable from NF1 and results in a small percentage of individuals being mischaracterized. Distinguishing these two entities is increasingly important for prognosis, reproductive planning, and clinical management. The goal of our study was to evaluate the cost impact of genetic testing for patients with solely pigmentary findings. The costs of genetic testing in patients aged 1.5–18 years were modeled using a simulated population, assuming the clinical management approach of a single NF1 clinic. Two genetic testing algorithms (SPRED1 testing alone, and NF1 mutation analysis with reflex to SPRED1) were compared against a baseline of no genetic testing. The cost for SPRED1 mutation analysis for each individual meeting NF1 diagnostic criteria without neoplastic or boney manifestation, when compared to the no‐testing approach with routine follow‐up mutations between the ages of 10 and 14 years, was minimal (range of $4–$16). Based on the clinical practice of one NF1 clinic, we found that the cost difference to perform SPRED1 mutation analysis on individuals who meet diagnostic criteria for NF1 without neoplastic or boney manifestation were minimal. Therefore it is important that “when to test decisions” remain a physician/patient discussion, as individual benefits may be greatest at a different age than when it is most cost efficient. © 2013 Wiley Periodicals, Inc. 相似文献