全文获取类型
收费全文 | 2435篇 |
免费 | 186篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 114篇 |
妇产科学 | 26篇 |
基础医学 | 268篇 |
口腔科学 | 180篇 |
临床医学 | 206篇 |
内科学 | 328篇 |
皮肤病学 | 44篇 |
神经病学 | 446篇 |
特种医学 | 228篇 |
外科学 | 238篇 |
综合类 | 146篇 |
一般理论 | 26篇 |
预防医学 | 165篇 |
眼科学 | 23篇 |
药学 | 114篇 |
中国医学 | 25篇 |
肿瘤学 | 54篇 |
出版年
2022年 | 12篇 |
2021年 | 15篇 |
2020年 | 17篇 |
2019年 | 25篇 |
2018年 | 38篇 |
2017年 | 31篇 |
2016年 | 41篇 |
2015年 | 30篇 |
2014年 | 63篇 |
2013年 | 109篇 |
2012年 | 101篇 |
2011年 | 110篇 |
2010年 | 80篇 |
2009年 | 73篇 |
2008年 | 102篇 |
2007年 | 132篇 |
2006年 | 80篇 |
2005年 | 82篇 |
2004年 | 87篇 |
2003年 | 56篇 |
2002年 | 62篇 |
2001年 | 50篇 |
2000年 | 62篇 |
1999年 | 86篇 |
1998年 | 85篇 |
1997年 | 59篇 |
1996年 | 48篇 |
1995年 | 35篇 |
1994年 | 40篇 |
1993年 | 40篇 |
1992年 | 55篇 |
1991年 | 58篇 |
1990年 | 58篇 |
1989年 | 65篇 |
1988年 | 67篇 |
1987年 | 51篇 |
1986年 | 50篇 |
1985年 | 56篇 |
1984年 | 24篇 |
1983年 | 38篇 |
1982年 | 22篇 |
1981年 | 18篇 |
1980年 | 24篇 |
1979年 | 19篇 |
1978年 | 33篇 |
1977年 | 16篇 |
1976年 | 20篇 |
1975年 | 16篇 |
1967年 | 11篇 |
1966年 | 15篇 |
排序方式: 共有2641条查询结果,搜索用时 15 毫秒
1.
2.
Changing attentional demands in left hemispatial neglect. 总被引:1,自引:0,他引:1
R F Kaplan M Verfaellie M E Meadows L R Caplan M S Pessin L D DeWitt 《Archives of neurology》1991,48(12):1263-1266
Seven variations of a letter cancellation test were used to examine how varying attentional demands affect hemispatial neglect in patients with right hemisphere lesions. While the 14 targets always remained in the same location, the number of distractors (zero, nine, 28, or 82) as well as their complexity (one letter or nine different letters) were varied. The percentage of targets canceled in the left hemispace was linearly related to the number of distractors. There were no differences between the complexity conditions. In a second study, the same 14 targets were presented but the distractors (zero, 14, or 41) were all placed on the right. Increasing the number of distractors on the right increased neglect on both sides of the space. Taken together, these results suggest that, while the limited attentional resources of the left hemisphere are biased toward the right hemispace, the absence of contralateral attentional demands allows these resources to be directed ipsilaterally. 相似文献
3.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
4.
Diagnosis and treatment of ischemic stroke 总被引:6,自引:0,他引:6
L R Caplan 《JAMA》1991,266(17):2413-2418
5.
6.
Maxillary sinusitis in adults: an evaluation of placebo-controlled double-blind trials 总被引:1,自引:0,他引:1
BACKGROUND: In general practice, acute sinusitis is frequently diagnosed
and treated with antibiotics. OBJECTIVE: This study aimed to determine the
evidence for the effectiveness of antibiotic treatment in acute maxillary
sinusitis in adults by assessing the methodological quality of
placebo-controlled double-blind randomized trials. METHOD: An evaluation by
four raters through a 35-item scoring-scale for internal and external
validity of all placebo-controlled double-blind randomized trials on acute
sinusitis found between January 1966 and July 1996. RESULTS: Eighty-five
trials were excluded because they were not placebo-controlled,
double-blind, randomized, or were carried out in patients with chronic
sinusitis or in children. The three remaining trials were performed in
different populations (one in general practice) between 1973 and 1978. Only
one study claimed superiority of antibiotic treatment. Different inclusion
criteria and major outcome measures were used by the authors. The
reliability of major outcome events was reported poorly or not at all and
in two studies outcome measures were clinically inappropriate. The studies
scored 30-62% of the maximum attainable score for internal validity and
10-20% for external validity. CONCLUSION: The effectiveness of antibiotic
treatment in acute maxillary sinusitis in a general practice population is
not based sufficiently on evidence.
相似文献
7.
8.
E Seidman N LeLeiko M Ament W Berman D Caplan J Evans S Kocoshis A Lake K Motil J Sutphen 《Journal of pediatric gastroenterology and nutrition》1991,12(4):424-438
Malnutrition, characterized by weight loss, growth failure and micronutrient depletion, are prominent features of inflammatory bowel disease (IBD) in the pediatric age group. Accurate evaluation of the patient's nutritional status and appropriate nutritional support, whether enteral or parenteral, constitute integral parts of the management of the growing child with IBD. Over the past two decades, a number of studies have supported the potential use of nutritional therapy to induce remission and to control disease activity in symptomatic Crohn's disease. More recently, preliminary studies on the use of dietary supplements of marine-oil-derived omega-3 fatty acids have also indicated a beneficial effect in IBD patients. In parallel with these clinical trials, scientific research has recently focused on the concept that specific dietary alterations can modulate the immune response. Components of the diet that may have particular relevance to mucosal immunity and the pathogenesis of IBD include polyunsaturated fatty acids, nucleotides, and amino acids such as glutamine and arginine. Future research in the interactions between specific nutrients and the immune system will likely increase our understanding of the causes of IBD, as well as enhance the development of novel nutritional therapies for IBD patients. 相似文献
9.
10.
H Angus-Leppan GA Lambert J Michalicek 《Cephalalgia : an international journal of headache》1997,17(6):625-630
Co-existence of facial and occipital pain may occur in occipital neuralgia, migraine and cluster headache; suggesting convergence of trigeminal and cervical afferents. Such convergence has been shown in humans and other animals, but the site and extent of this are uncertain. In anaesthetized adult cats, the superior sagittal sinus and occipital nerve were stimulated electrically, and extracellular recordings made in the dorsolateral area of the upper cervical cord using glass-coated tungsten electrodes. Of 49 units in 10 cats, 33 (67%) had input from the superior sagittal sinus and the occipital nerve. Thirteen (27%) had superior sagittal sinus input and 3 (6%) had occipital nerve input. Convergent receptive fields were identified mechanically in 7 units. These experiments in cats show convergent input from occipital nerve and superior sagittal sinus on dorsolateral area units in two-thirds of cases studied. This experimental site of trigeminocervical convergence may relate to referral of pain in occipital neuralgia and other headaches. 相似文献