全文获取类型
收费全文 | 882篇 |
免费 | 60篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 41篇 |
妇产科学 | 8篇 |
基础医学 | 73篇 |
口腔科学 | 65篇 |
临床医学 | 85篇 |
内科学 | 126篇 |
皮肤病学 | 11篇 |
神经病学 | 14篇 |
特种医学 | 189篇 |
外科学 | 102篇 |
综合类 | 76篇 |
预防医学 | 55篇 |
眼科学 | 4篇 |
药学 | 45篇 |
中国医学 | 24篇 |
肿瘤学 | 23篇 |
出版年
2022年 | 6篇 |
2021年 | 3篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 27篇 |
2013年 | 53篇 |
2012年 | 48篇 |
2011年 | 40篇 |
2010年 | 45篇 |
2009年 | 37篇 |
2008年 | 35篇 |
2007年 | 51篇 |
2006年 | 17篇 |
2005年 | 16篇 |
2004年 | 13篇 |
2003年 | 6篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 58篇 |
1997年 | 49篇 |
1996年 | 36篇 |
1995年 | 25篇 |
1994年 | 33篇 |
1993年 | 25篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 20篇 |
1988年 | 27篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 21篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1975年 | 7篇 |
1974年 | 5篇 |
1971年 | 4篇 |
1954年 | 1篇 |
排序方式: 共有947条查询结果,搜索用时 15 毫秒
1.
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
2.
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
3.
4.
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
5.
In patients with PG-dependent renal function, NSAID administration
constantly reduces GFR and RBF in a dose-dependent fashion. In this
situation, the risk of overt acute renal failure is high and should be
taken into proper account. In contrast, the incidence of NSAID-related
renal structural alterations appears to be very low, yet the absolute
number of patients may be significant considering the wide use of such
drugs. Concerning the antiproteinuric effect of NSAIDs, the unfavourable
ratio risk/benefit does not seem to support their indication in proteinuric
nephropathies. The development of PGHS-2 selective inhibitors is promising,
and may open new therapeutical strategies in the treatment of the
progression of renal disease.
相似文献
6.
P A Grant W S Egerton G Strutton G Balderson 《The Australian and New Zealand journal of surgery》1988,58(1):67-71
When haemostatic clamps are applied, evidence of injury at the site of clamp application may be seen when the clamp is removed. Rarely, the intima may be disrupted. When a new arterial clamp became available, a study was designed to compare the Martin Titanline arterial clamp (13-143-35, curved arterial clamp) with several other arterial clamps already in use. The Martin clamp is a modified pivot-point, preset-tension, spring-controlled arterial clamp. The closing pressures of several clamps were measured objectively. The injury produced when the clamps were applied to occlude the blood flow on the carotid artery of a dog was assessed by histological study of the excised segments of the arterial wall. Histological cross-sections were prepared from canine carotid artery which had been perfused for 1 h after the clamp had been applied for 1 h. Histological evidence of injury was limited to disruption of the intimal layer and compression of the medial layer. No significant difference between the amount of damage caused by the DeBakey, Satinsky or Martin clamp was identified. When compared to the other varieties of clamp listed above, the Martin clamp had a significantly lower closing pressure (304 g) compared with 580g (Bulldog), 580 g (Satinsky), and 686 g (DeBakey). The Martin clamp was easier to apply, did not obstruct the operative field as readily and had good clamp-retention characteristics throughout the procedure. 相似文献
7.
8.
Rebecca Setliff Janet E Porter Michael Malison Steve Frederick Thomas R Balderson 《JPHMP》2003,9(2):91-102
To address the need for management development in public health, the Centers for Disease Control and Prevention (CDC) established three independent workforce development initiatives aimed primarily at strengthening management and leadership capacity: the Sustainable Management Development Program, the Management Academy for Public Health, and the CDC Leadership and Management Institute. Though independently designed and implemented, the programs share similar guiding principles in their approach to management development: interactive (adult) learning, management tools that reinforce evidence-based decision making, individual feedback, continuous improvement of the learning process, posttraining support for networking and life-long learning, and teamwork. This article will discuss important lessons learned regarding best practices in management and leadership development. 相似文献
9.
10.