全文获取类型
收费全文 | 1335791篇 |
免费 | 94291篇 |
国内免费 | 2908篇 |
专业分类
耳鼻咽喉 | 19713篇 |
儿科学 | 40225篇 |
妇产科学 | 38659篇 |
基础医学 | 187200篇 |
口腔科学 | 39817篇 |
临床医学 | 112614篇 |
内科学 | 262361篇 |
皮肤病学 | 30205篇 |
神经病学 | 106358篇 |
特种医学 | 53665篇 |
外国民族医学 | 435篇 |
外科学 | 208206篇 |
综合类 | 31044篇 |
现状与发展 | 6篇 |
一般理论 | 436篇 |
预防医学 | 92030篇 |
眼科学 | 31357篇 |
药学 | 100053篇 |
4篇 | |
中国医学 | 2988篇 |
肿瘤学 | 75614篇 |
出版年
2018年 | 11737篇 |
2015年 | 11871篇 |
2014年 | 16683篇 |
2013年 | 25237篇 |
2012年 | 32993篇 |
2011年 | 34858篇 |
2010年 | 20727篇 |
2009年 | 20224篇 |
2008年 | 33569篇 |
2007年 | 36674篇 |
2006年 | 37248篇 |
2005年 | 36003篇 |
2004年 | 35080篇 |
2003年 | 34057篇 |
2002年 | 33584篇 |
2001年 | 63613篇 |
2000年 | 65322篇 |
1999年 | 55386篇 |
1998年 | 14650篇 |
1997年 | 13458篇 |
1996年 | 12937篇 |
1995年 | 12221篇 |
1994年 | 11467篇 |
1992年 | 42761篇 |
1991年 | 41280篇 |
1990年 | 40553篇 |
1989年 | 39550篇 |
1988年 | 36963篇 |
1987年 | 36408篇 |
1986年 | 34899篇 |
1985年 | 33101篇 |
1984年 | 24822篇 |
1983年 | 21052篇 |
1982年 | 12664篇 |
1981年 | 11568篇 |
1980年 | 10772篇 |
1979年 | 23923篇 |
1978年 | 17068篇 |
1977年 | 14834篇 |
1976年 | 13386篇 |
1975年 | 15267篇 |
1974年 | 18080篇 |
1973年 | 17560篇 |
1972年 | 16810篇 |
1971年 | 15717篇 |
1970年 | 14914篇 |
1969年 | 14346篇 |
1968年 | 13460篇 |
1967年 | 12015篇 |
1966年 | 11258篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Jorge Guardado Carlos Cotrim Otília Sim?es Sofia Almeida Mário Ialá Luís Lopes Hélder Pereira Manuel Carrageta 《Revista portuguesa de cardiologia》2006,25(4):409-415
INTRODUCTION: Transesophageal echocardiography (TEE) has become increasingly useful in the study of patients with suspected pulmonary thromboembolism. OBJECTIVE: The aim of this study was to prospectively evaluate the usefulness of TEE in the study of the distal part of the left pulmonary artery (LPA) as well as the influence of this procedure on total echocardiographic exam duration. METHODOLOGY: A prospective study in two groups of consecutive patients referred for TEE with a one- year interval between evaluation of Group A: 33 patients, 17 male, mean age 54 +/- 24 years, and Group B: 42 patients, 20 male, mean age 48 +/- 27 years (p = NS). The procedure was considered long when it took more than 3 min to evaluate the distal part of the LPA. RESULTS: In group A we were able to visualize the distal part of the LPA in 24 patients (73%) without significant prolongation of total exam duration in 16 patients (48% of group A). In one of the patients with suspected pulmonary thromboembolism thrombi were only observed in the distal part of the LPA. In group B we were able to visualize the distal part of the LPA in 36 patients (86%) without significant prolongation of total exam duration in 26 patients (61% of group B). CONCLUSIONS: 1. Visualization of the distal part of the LPA was possible in more patients, and with TEE time prolongation in less patients, in group B. These differences can be accounted for by the training of the operator in this technique. 2. The importance of visualization of this part of the LPA in guiding treatment in the subset of patients with pulmonary thromboembolism confirms the usefulness of this specific procedure. 相似文献
122.
123.
Gil Bolotin Frederik H. van der Veen Roberto Lorusso Tamir Wolf Robert Sachner Rona Shofti Jan J. Shreuder Gideon Uretzky 《European journal of cardio-thoracic surgery》2002,21(6):975-980
Objective: Descending and ascending aortomyoplasty are two surgical procedures intended to induce hemodynamic benefits similar to those of the intra-aortic-balloon-pump (IABP). To date, there have been no studies comparing the two surgical techniques. The objective of this study was to compare coronary blood flow augmentation and afterload reduction as produced by descending and ascending aortomyoplasty counterpulsation Methods: Twenty-two mongrel dogs (18–35 kg) underwent IABP application (n=7), descending (n=8), or ascending (n=7) aortomyoplasty. Left anterior descending (LAD) coronary artery blood flow was measured using a Transonic Doppler flow probe. Left ventricular pressure as well as aortic pressures proximal and distal to either the aortomyoplasty site or the IABP position were monitored continuously. Results: Descending aortomyoplasty induced higher elevation in the LAD blood flow during assisted beats (27% from 10.8±4 to 13.8±6 ml/min, P<0.001) than that induced by either ascending aortomyoplasty (19% from 11.7±5 to 14±5 ml/min, P<0.001) or IABP counterpulsation (18% from 8.6±3 to 10.2±4 ml/min, P<0.001). Conversely, while ascending aortomyoplasty reduced the left ventricular end-diastolic pressure by 16% (from 60±18 to 50±22 mmHg, P<0.001), similar to the 16% after load reduction achieved by the IABP counterpulsation, descending aortomyoplasty failed to induce afterload reduction. Conclusions: Descending aortomyoplasty produces higher coronary blood flow augmentation than either ascending aortomyoplasty or IABP. However, afterload reduction comparable to that achieved by IABP was observed only with ascending aortomyoplasty and not with descending aortomyoplasty. 相似文献
124.
The authors studied the cumulative probability of pregnancy for up to 4 consecutive embryo transfer (ET) cycles with ICSI performed for male factor. Transfers could be either fresh or frozen. The clinical pregnancy rate (PR) for the first 4 cycles were similar [44% (61/366); 31% (44/138); 45% (14/31); 44% (4/9)]. Delivery rates were also similar. There was a lower PR on the second retrieval vs. the first retrieval (47% vs. 29%), but this may be related to most of the second retrievals occurring in the second transfer cycle (67%, 31/55); this may be explained by women who were poor responders and required another retrieval without a frozen ET. The majority of transfers in cycle 1 were fresh, whereas cycles 2-4 used primarily frozen-thawed embryos. These data should be helpful for patients requiring IVF with ICSI in deciding to continue with more IVF cycles or consider other 相似文献
125.
126.
Angiotensin Converting Enzyme Inhibitors: Animal Experiments Suggest a New Pharmacological Treatment for Alcohol Abuse in Humans 总被引:1,自引:0,他引:1
G. Spinosa MSc E. Perlanski Dipl Tech. F. H. H. Leenen MD R. B. Stewart MSc L. A. Grupp DSc 《Alcoholism, clinical and experimental research》1988,12(1):65-70
The prevalence of heavy alcohol consumption is a major problem of increasing proportions throughout the world. Although alcohol sensitizing drugs and more recently serotonin uptake inhibitors are drug interventions with some following, their long term beneficial consequences have yet to be demonstrated. In recent years, we have demonstrated that manipulating activity in the renin-angiotensin system will dramatically alter voluntary alcohol consumption in rats. Based on these findings, the present study evaluated the ability of a class of drugs known as the angiotensin converting enzyme inhibitors to reduce voluntary alcohol drinking in laboratory animals. These drugs prevent the conversion of angiotensin I to angiotensin II. They have been licensed for use in Europe and North America and are indicated in the treatment of hypertension. Our experiments showed that both captopril (Capoten, Squibb) and enalapril (Vasotec, Merck Sharpe & Dohme) can reduce alcohol drinking in both normotensive and hypertensive animals regardless of whether the pattern of intake is in a bout or of a less exaggerated nature. Furthermore, this change in alcohol intake can occur without concomitant changes in blood pressure, plasma renin activity, overall fluid balance, or the distribution and metabolism of alcohol. Taken together these findings suggest that the angiotensin converting enzyme inhibitors should be evaluated in a clinical setting for they may prove to be a useful new treatment or treatment adjunct for alcohol abuse in humans. 相似文献
127.
A prospective randomized study was done to compare the fluid contamination rates of two methods used to determine cardiac output by thermodilution under in-use conditions. Fifty patients were randomly assigned to have cardiac output measured by the capped syringe or closed loop method, and were followed with quantitative cultures of fluid and catheter. The two treatment groups (n = 25 each) were comparable in terms of age, sex, intensive care unit location, underlying diagnosis, and mean number of cardiac output determinations performed in the first 24 hours after placement of the catheter line. No differences in the rates of fluid contamination were seen at any time between the two groups. The overall fluid contamination rate was 2/124 cultures (1.8% with 95% confidence interval +/- 4.1%) with one colony of Staphylococcus epidermidis from a closed loop sample and one colony of Pseudomonas maltophilia in a capped syringe sample. Although no difference in contamination rates was documented, the closed loop system required less nursing time and effort. 相似文献
128.
H Struck 《Zeitschrift für Gerontologie》1988,21(2):106-109
Today old age represents no contraindication to operative treatment. The age dependence of normal coagulation, immunological system and connective tissue components is described with respect to the course of wound healing. Possible misinterpretations that may occur, if preoperative values do not exist and the subsequent course is not observed, are pointed out. 相似文献
129.
The role of hypertension and antihypertensive drugs in cardiovascular complications was evaluated in 380 elderly people living in the Tokyo Metropolitan Gerontology Center. The subjects were classified into four groups according to the presence or absence of hypertension and their antihypertensive treatment, and followed up prospectively for 5 years from 1979 to 1984. The average age of each group was 74 to 76 years. Cerebrovascular disease was observed in 19.3% of male hypertensives and 10.1% of male normotensives (p = 0.078). The drug treated group revealed no cerebral hemorrhage and less cerebral infarction. This tendency was not observed in females. Ischemic heart disease was prevalent in the drug treated group (10.9% vs 4.5%, p = 0.023) irrespective of blood pressure level. Risk factors such as body mass index, skinfold thickness, serum cholesterol, albumin, creatinine, blood urea nitrogen and uric acid at entry were elevated in the drug treated group. Diuretics were used in 92% of the drug treated group; in 53% as monotherapy and in 39% as combination therapy with other antihypertensive agents. The metabolic effect of diuretics may increase the incidence of ischemic heart disease in the elderly. We might conclude that hypertension in the aged accelerates cerebrovascular complications, and that antihypertensive treatment is effective even in this group. However, the wide use of diuretics could increase the incidence of ischemic heart disease. Careful selection of antihypertensive drugs as well as dose adjustment are needed in the treatment of elderly hypertensives. 相似文献
130.
Despite growing concern with rural elderly populations, little attention has focused on their mental health, ways it may correlate with physical health, or how rural mental health patterns compare to urban. Popular wisdom contends that elderly people in general, and rural elderly persons in particular, are at increased risk for mental illness. This article examines these questions. A review of available literature suggests that elderly people may be at only slightly greater risk of mental illness than the population at large, though there are some indications that rates of depression may be somewhat higher among the elderly population. Much of this same literature implies that objective environmental conditions play a significant role in the incidence of depression. Analysis of data gathered in a statewide random poll (N = 743) indicates that while physical health tends to be poorer among rural populations, when health is held constant there is actually an inverse relationship between age and depression. Therefore, rural elderly persons are no more likely to be depressed than their urban counterparts despite harsher living conditions. Both conceptual and policy implications are discussed. 相似文献