全文获取类型
收费全文 | 241066篇 |
免费 | 5671篇 |
国内免费 | 662篇 |
专业分类
耳鼻咽喉 | 2023篇 |
儿科学 | 8157篇 |
妇产科学 | 4384篇 |
基础医学 | 25264篇 |
口腔科学 | 2650篇 |
临床医学 | 18297篇 |
内科学 | 45679篇 |
皮肤病学 | 2168篇 |
神经病学 | 22225篇 |
特种医学 | 11593篇 |
外国民族医学 | 1篇 |
外科学 | 37777篇 |
综合类 | 3365篇 |
一般理论 | 45篇 |
预防医学 | 22180篇 |
眼科学 | 4344篇 |
药学 | 14585篇 |
1篇 | |
中国医学 | 1016篇 |
肿瘤学 | 21645篇 |
出版年
2023年 | 445篇 |
2022年 | 922篇 |
2021年 | 1701篇 |
2020年 | 976篇 |
2019年 | 1524篇 |
2018年 | 23402篇 |
2017年 | 18468篇 |
2016年 | 20870篇 |
2015年 | 2914篇 |
2014年 | 3369篇 |
2013年 | 4004篇 |
2012年 | 11648篇 |
2011年 | 25895篇 |
2010年 | 21589篇 |
2009年 | 14001篇 |
2008年 | 23336篇 |
2007年 | 25745篇 |
2006年 | 4472篇 |
2005年 | 6118篇 |
2004年 | 6824篇 |
2003年 | 7641篇 |
2002年 | 5518篇 |
2001年 | 1342篇 |
2000年 | 1331篇 |
1999年 | 1175篇 |
1998年 | 900篇 |
1997年 | 765篇 |
1996年 | 622篇 |
1995年 | 544篇 |
1994年 | 493篇 |
1993年 | 430篇 |
1992年 | 571篇 |
1991年 | 534篇 |
1990年 | 569篇 |
1989年 | 504篇 |
1988年 | 479篇 |
1987年 | 393篇 |
1986年 | 324篇 |
1985年 | 372篇 |
1984年 | 407篇 |
1983年 | 340篇 |
1982年 | 351篇 |
1981年 | 323篇 |
1980年 | 354篇 |
1979年 | 243篇 |
1978年 | 226篇 |
1977年 | 204篇 |
1976年 | 172篇 |
1975年 | 136篇 |
1974年 | 164篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Cindy L. Grines 《Journal of nuclear cardiology》1994,1(5):S131-S133
During the past few decades, management of patients with myocardial infarction has dramatically evolved. High-risk patients are now identified by a variety of noninvasive tests, and aggressive use of reperfusion strategies has improved clinical outcomes. Despite the benefits of reperfusion, only a few patients are eligible to receive thrombolytic therapy. Mortality rates among patients excluded from thrombolytic trials (15% to 20%) have been far greater than those eligible for treatment (3% to 10%). Because most deaths occur within the first few days of infarction, interventions designed to reduce mortality should be performed acutely. Immediate catheterization allows identification of high-risk anatomy that may benefit from surgery and allows coronary angioplasty to be performed as a reperfusion strategy (when appropriate). Furthermore, catheterization allows documentation of ejection fraction, vessel patency, number of diseased vessels, and residual stenosis, all of which have been predictive of prognosis. Conversely, frequently repeated noninvasive diagnostic tests are associated with increased cost, are generally performed in low-risk patients, and 60% to 80% of patients with myocardial infarction ultimately require catheterization anyway. It is possible that early catheterization and percutaneous transluminal coronary angioplasty when indicated may effectively risk stratify patients (eliminating the need for noninvasive testing), may reduce morbidity and mortality, and shorten the length of hospital stay. 相似文献
122.
Daniel W. Walsh Vincent B. Ho Michael F. Haggerty 《Journal of magnetic resonance imaging : JMRI》1997,7(2):312-315
Mycotic aneurysms of the abdominal aorta are potentially fatal but uncommon. We report the MRI and MRA features of an abdominal aortic mycotic aneurysm in a patient who presented with nonspecific low back pain. By delineating the saccular nature of the aneurysm and identifying the coexistence of vertebral enhancement, MRI was crucial for the final diagnosis. A potential pitfall of contrast-enhanced MRA is also demonstrated. 相似文献
123.
Martin E. Weinand Bruce Hermann Allen R. Wyler L. Philip Carter K. J. Oommen David Labiner Geoff Ahern Anne Herring 《Epilepsia》1994,35(5):1054-1059
Summary: We report a series of 8 patients with ictal déjà vu. Subdural strip electrocorticographic (ECoG) monitoring localized the ictal epileptogenic focus as follows: right (n = 6) and left (n = 2) mesiotemporal lobe. In all 8 patients, the left hemisphere was dominant for language function based on intracarotid amytal testing. In 6 right-handed patients, ictal déjà vu was associated with a right temporal lobe focus. However, in the 2 left-handed patients, the ictal focus was left temporal lobe. Although ictal déjà vu localizes the epileptic focus to temporal lobe, this experiential phenomenon appears to lateralize to the hemisphere nondominant for handedness. 相似文献
124.
125.
126.
127.
128.
Raymond J. Gibbons 《Journal of nuclear cardiology》1994,1(5):S118-S130
Both radionuclide angiography and myocardial perfusion imaging provide important insights that determine the management of patients with stable coronary artery disease. Both nuclear cardiology procedures have clearly demonstrated use in the noninvasvie identification of severe (left main or three-vessel) coronary artery disease and the noninvasive assessment of prognosis and thereby determine which patients should be sent to coronary angiography. Both radionuclide angiography and myocardial perfusion imaging provide prognostic information that is independent of resting left ventricular function and coronary anatomy and thereby influence the decision regarding which patients should be sent to coronary revascularization. This review considers the evidence supporting the uses of these nuclear cardiology procedures and provides suggestions regarding their cost-effective application. 相似文献
129.
Philip J. Larsen David S. Jessop Hardial S. Chowdrey Stafford L. Lightman Jens D. Mikkelsen 《Journal of neuroendocrinology》1994,6(2):153-159
The complete sequence of the cDNA encoding the neuropeptide Y (NPY) Y1-receptor has recently been deduced from a rat brain library, and the presence of messenger ribonucleic acid (mRNA) encoding Y1-receptor protein has been demonstrated within the brain. Using quantitative in situ hybridization histochemistry, the content and distribution of Y1receptor and preproNPY mRNAs have been investigated in the hypothalamic arcuate nucleus of adrenalectomized rats receiving glucocorticoid replacement therapy for 12 days by means of either high doses of dexamethasone in their drinking water or by subcutaneous corticosterone pellets. Basal metabolic parameters such as weight gain or loss, blood glucose and plasma insulin were monitored: Dexamethasone treatment induced weight loss and a state of hyperinsulinemia with normoglycemia, while corticosterone treated animals displayed metabolic parameters identical to sham ADX animals. Within the arcuate nucleus of glucocorticoid treated animals, levels of Y1receptor and preproNPY mRNAs were increased. In contrast, adrenalectomy itself had no effect upon Y1-receptor mRNA levels or preproNPY mRNA levels in the arcuate nucleus. These studies demonstrate that glucocorticoids exert a stimulatory action on levels of Y1-receptor mRNA and preproNPY mRNA levels in the hypothalamic arcuate nucleus. This is the first evidence to suggest that the expression of a neuropeptide-receptor gene in the central nervous system may be directly sensitive to peripheral hormonal signals. 相似文献
130.
Judith A. MacNaughton Mohan L. Bangah' Philip I. McCloudt Henry G. Burger 《Clinical endocrinology》1991,35(4):341-346
OBJECTIVE: Normal elderly men are reported to have decreased testicular function despite elevated gonadotrophin levels. We wished therefore to determine if changes in testicular function occur over the age range 19-60 years. DESIGN: Single fasting blood samples were obtained between 0800 and 0900 h. PATIENTS: Working men in a large industrial company between the ages of 19 and 60 years participated in the study. MEASUREMENTS: FSH, serum immunoreactive inhibin and total testosterone were measured, the latter two as measurements of Sertoli and Leydig cell function respectively. RESULTS: The mean baseline serum immunoreactive inhibin level was significantly lower in men from the older age groups, 31-40 years (479 U/l), 41-50 years (439 U/l) and 51-60 years (415 U/l) than in men from the youngest age group, 21-30 years (613 U/l) while serum FSH was higher in men from the older age groups, 41-50 years (3.7 IU/l) and 51-60 years (6.1 IU/l) than in men from the youngest age group, 21-30 years (2.6 IU/l). There appears to be a change in both FSH and inhibin production, consistent with a primary decline in testicular function. There was no significant difference in testosterone levels between the older age group, age 51-60 years and the younger age group, age 21-30 years. However, testosterone levels were significantly lower in the 41-50 year age group, when compared with the 21-30 year, this significance levelling out at about age 45 years. CONCLUSION: The data are consistent with the hypothesis that immunoreactive inhibin reflects inhibin bioactivity, and that inhibin plays a role in the feedback control of FSH secretion in men. 相似文献