全文获取类型
收费全文 | 12138篇 |
免费 | 698篇 |
国内免费 | 67篇 |
专业分类
耳鼻咽喉 | 114篇 |
儿科学 | 339篇 |
妇产科学 | 228篇 |
基础医学 | 1287篇 |
口腔科学 | 557篇 |
临床医学 | 1017篇 |
内科学 | 2793篇 |
皮肤病学 | 221篇 |
神经病学 | 706篇 |
特种医学 | 355篇 |
外国民族医学 | 4篇 |
外科学 | 1819篇 |
综合类 | 527篇 |
一般理论 | 10篇 |
预防医学 | 775篇 |
眼科学 | 322篇 |
药学 | 1023篇 |
中国医学 | 69篇 |
肿瘤学 | 737篇 |
出版年
2024年 | 14篇 |
2023年 | 186篇 |
2022年 | 589篇 |
2021年 | 804篇 |
2020年 | 409篇 |
2019年 | 492篇 |
2018年 | 615篇 |
2017年 | 339篇 |
2016年 | 387篇 |
2015年 | 396篇 |
2014年 | 522篇 |
2013年 | 653篇 |
2012年 | 938篇 |
2011年 | 927篇 |
2010年 | 467篇 |
2009年 | 397篇 |
2008年 | 608篇 |
2007年 | 615篇 |
2006年 | 552篇 |
2005年 | 539篇 |
2004年 | 541篇 |
2003年 | 425篇 |
2002年 | 438篇 |
2001年 | 91篇 |
2000年 | 76篇 |
1999年 | 68篇 |
1998年 | 87篇 |
1997年 | 54篇 |
1996年 | 46篇 |
1995年 | 58篇 |
1994年 | 42篇 |
1993年 | 29篇 |
1992年 | 26篇 |
1991年 | 42篇 |
1990年 | 34篇 |
1989年 | 36篇 |
1988年 | 25篇 |
1987年 | 24篇 |
1986年 | 38篇 |
1985年 | 22篇 |
1984年 | 26篇 |
1983年 | 24篇 |
1982年 | 16篇 |
1981年 | 25篇 |
1980年 | 18篇 |
1979年 | 22篇 |
1978年 | 17篇 |
1977年 | 13篇 |
1975年 | 11篇 |
1974年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
A K Teiling A K Mohammed B G Minor T U J?rbe A J Hiltunen T Archer 《Anesthesia and analgesia》1987,66(6):533-541
The objective of this investigation was to study the effects of lidocaine upon postnatal development of the rat. Lidocaine, 6 mg/kg (21 mumol/kg), was given to a group of 12 rats. Injections were administered intramuscularly, bilaterally in the masseter muscles, once a day on days 10 and 11 of pregnancy. Twelve control rats were given physiologic saline. Clinical signs, mortality, body weight, and food consumption were recorded during pregnancy and lactation. The duration of gestation was also recorded. The development of the offspring was monitored by tests of spontaneous activity, nociception, learning ability, and physical development. No clinical signs of adverse reactions were seen in any of the groups. In the majority of the learning ability tests, the control and lidocaine-treated groups showed similar results. However, in the schedule of differential reinforcement of low rates of responding (DRL 20), the lidocaine-exposed males received more reinforcements than the controls and made fewer responses. In the tests of nociception, a significant difference between sexes was recorded, in that the females were more sensitive than the males in the shock-titration test. Physical development, as monitored by swimming ability and spontaneous activity, showed no inter-group difference. The present results indicate that prenatal exposure to lidocaine fails to result in postnatal impairment of the development of behavioral performance of a wide range of tasks. 相似文献
12.
BACKGROUND: The maximum number of hair grafts that can be safely implanted in 1 cm2 is still debatable. To our knowledge, no previous report has addressed this issue in three dimensions, taking into account the size, the angle of the graft, and the intergraft distance. OBJECTIVES: To study the effect of the size and angle of the graft and the intergraft distance on dense packing. METHODS: Using a mathematical formula (the maximum number of hair grafts in 1 cm2 = 33 * cosine), the volume of the recipient area and the volume of the hair graft are calculated, assuming that the surface area of the recipient area is 1 cm2, the diameter of the hair graft is 1 mm, and the intergraft distance is 1.5 mm laterally and 1 mm anteriorly and posteriorly. RESULTS: The maximum number of hair grafts that could be implanted in 1 cm2 at a 90 angle in relation to the skin surface is 33 grafts, at a 60 angle is 28 grafts, and at a 30 angle is 16 grafts. CONCLUSION: The maximum number of hair grafts that can be implanted in any given recipient area depends on the graft size, the angle or direction of these grafts, and the intergraft distance. Where more space is allowed between the grafts, and the more acute the angle, the fewer hair grafts that can be implanted. 相似文献
13.
中面部年轻化手术进展 总被引:4,自引:4,他引:0
随着生活水平的提高,人们越来越关注并热切希望改善自己的外表,许多整形外科医生都在努力探索各种美容手术方法,以期最终能达到使患者衰老的面容年轻化的目的。最初的方法主要是通过直接切除多余的皮肤。 相似文献
14.
Genetic diversity and molecular identification of mosquito species in the Anopheles maculatus group using the ITS2 region of rDNA. 总被引:2,自引:0,他引:2
C Walton P Somboon S M O'Loughlin S Zhang R E Harbach Y-M Linton B Chen K Nolan S Duong M-Y Fong I Vythilingum Z D Mohammed Ho Dinh Trung R K Butlin 《Infection, genetics and evolution》2007,7(1):93-102
The species diversity and genetic structure of mosquitoes belonging to the Anopheles maculatus group in Southeast Asia were investigated using the internal transcribed spacer 2 (ITS2) of ribosomal DNA (rDNA). A molecular phylogeny indicates the presence of at least one hitherto unrecognised species. Mosquitoes of chromosomal form K from eastern Thailand have a unique ITS2 sequence that is 3.7% divergent from the next most closely related taxon (An. sawadwongporni) in the group. In the context of negligible intraspecific variation at ITS2, this suggests that chromosomal form K is most probably a distinct species. Although An. maculatus sensu stricto from northern Thailand and southern Thailand/peninsular Malaysia differ from each other in chromosomal banding pattern and vectorial capacity, no intraspecific variation was observed in the ITS2 sequences of this species over this entire geographic area despite an extensive survey. A PCR-based identification method was developed to distinguish five species of the group (An. maculatus, An. dravidicus, An. pseudowillmori, An. sawadwongporni and chromosomal form K) to assist field-based studies in northwestern Thailand. Sequences from 187 mosquitoes (mostly An. maculatus and An. sawadwongporni) revealed no intraspecific variation in specimens from Thailand, Cambodia, mainland China, Malaysia, Taiwan and Vietnam, suggesting that this identification method will be widely applicable in Southeast Asia. The lack of detectable genetic structure also suggests that populations of these species are either connected by gene flow and/or share a recent common history. 相似文献
15.
16.
The evolution of a biodegradable membrane for use in urological surgery. A summary of 109 in vivo experiments 总被引:3,自引:0,他引:3
R Scott R Mohammed S D Gorham D A French M J Monsour A Shivas T Hyland 《British journal of urology》1988,62(1):26-31
The evolution of a collagen/vicryl composite membrane designed as a prosthetic material for use in urinary tract surgery is described. The early experiments in which collagen film alone was used to repair experimental ureterotomies are reviewed together with our first experiments with the collagen/vicryl prosthesis in the repair of partial nephrectomies and of full thickness defects created in the urinary bladder of experimental rabbits. These early results led to the preparation of a composite using a more highly purified collagen and employing a method of sterilisation (gamma irradiation) which would be acceptable for regular use in medical products. The results of a further series of partial nephrectomy and full thickness bladder repairs show that irradiation does not compromise the efficacy of the collagen/vicryl composite in vivo. 相似文献
17.
18.
B G Henriksson S S?derstr?m A J Gower T Ebendal B Winblad A H Mohammed 《Behavioural brain research》1992,48(1):15-20
Brain nerve growth factor (NGF) was determined in two groups of aged rats: 'good' and 'poor' performers. The animals were selected out of a population of 40 aged rats (26-28 months old) trained in a spatial learning task. Animals performing well in the test had significantly higher NGF in the hippocampus when compared to 'poor' performers. No differences in the levels of NGF were found in the cortex, septum and cerebellum. The results implicate hippocampal NGF in cognitive functioning of aged rats, and suggests that the forebrain cholinergic neuronal atrophy which has been observed in cognitively impaired aged rats may be due to reduced availability of target-derived NGF. 相似文献
19.
Sendhil K Balasubramanian Ravindranath Tiruvoipati Mohammed Amin Kanakkande K Aabideen Giles J Peek Andrew W Sosnowski Richard K Firmin 《Journal of cardiothoracic surgery》2007,2(1):4-9
Background
Veno-arterial extracorporeal membrane oxygenation (ECMO) is a common modality of circulatory assist device used in children. We assessed the outcome of children who had ECMO following repair of congenital cardiac defects (CCD) and identified the risk factors associated with hospital mortality. 相似文献20.
Propofol versus traditional sedative agents for gastrointestinal endoscopy: a meta-analysis. 总被引:6,自引:0,他引:6
Mohammed A Qadeer John J Vargo Farah Khandwala Rocio Lopez Gregory Zuccaro 《Clinical gastroenterology and hepatology》2005,3(11):1049-1056
BACKGROUND & AIMS: Even though propofol has better recovery profile than traditional agents, its use is limited because of the perception of increased complication rates. Because an adequately powered trial comparing risk of propofol with traditional agents is lacking, we performed a meta-analysis of the current literature. METHODS: We searched Medline (1966-October 2004), EMBASE (1980-October 2004), and Cochrane controlled trials registry. The following 4 cardiopulmonary complications were assessed: hypoxia, hypotension, arrhythmias, and apnea. Procedures were divided into 3 groups: esophagogastroduodenoscopy group, colonoscopy group, and endoscopic retrograde cholangiopancreatography/endoscopic ultrasonography group. Pooled odds ratios for complications were calculated for all the procedures combined and then separately for the 3 groups. Random effects models were used for 2-proportion comparisons. RESULTS: Of the 90 citations identified, 12 original studies qualified for this meta-analysis and included 1161 patients. Of these, 634 received propofol, and 527 received midazolam, meperidine, and/or fentanyl. Most of the included studies were randomized trials of moderate quality and nonsignificant heterogeneity (Cochran Q = 4.81, P = .90). Compared with traditional sedative agents, the pooled odds ratio with the use of propofol for developing hypoxia or hypotension for all the procedures combined was 0.74 (95% confidence interval [CI], 0.44-1.24); for EGD, 0.85 (95% CI, 0.33-2.17); for colonoscopy, 0.4 (95% CI, 0.2-0.79); and for ERCP/EUS, 1.07 (95% CI, 0.38-3.01). CONCLUSIONS: Propofol sedation during colonoscopy appears to have lower odds of cardiopulmonary complications compared with traditional agents, but for other procedures, the risk of complications is similar. 相似文献