全文获取类型
收费全文 | 26268篇 |
免费 | 1729篇 |
国内免费 | 82篇 |
专业分类
耳鼻咽喉 | 222篇 |
儿科学 | 644篇 |
妇产科学 | 448篇 |
基础医学 | 3884篇 |
口腔科学 | 339篇 |
临床医学 | 2434篇 |
内科学 | 6343篇 |
皮肤病学 | 671篇 |
神经病学 | 2211篇 |
特种医学 | 797篇 |
外国民族医学 | 3篇 |
外科学 | 3787篇 |
综合类 | 270篇 |
一般理论 | 28篇 |
预防医学 | 1946篇 |
眼科学 | 489篇 |
药学 | 1610篇 |
1篇 | |
中国医学 | 56篇 |
肿瘤学 | 1896篇 |
出版年
2022年 | 134篇 |
2021年 | 335篇 |
2020年 | 226篇 |
2019年 | 359篇 |
2018年 | 422篇 |
2017年 | 288篇 |
2016年 | 353篇 |
2015年 | 413篇 |
2014年 | 625篇 |
2013年 | 945篇 |
2012年 | 1400篇 |
2011年 | 1559篇 |
2010年 | 939篇 |
2009年 | 954篇 |
2008年 | 1490篇 |
2007年 | 1655篇 |
2006年 | 1650篇 |
2005年 | 1742篇 |
2004年 | 1600篇 |
2003年 | 1531篇 |
2002年 | 1515篇 |
2001年 | 404篇 |
2000年 | 337篇 |
1999年 | 392篇 |
1998年 | 377篇 |
1997年 | 337篇 |
1996年 | 294篇 |
1995年 | 277篇 |
1994年 | 259篇 |
1993年 | 232篇 |
1992年 | 323篇 |
1991年 | 301篇 |
1990年 | 275篇 |
1989年 | 255篇 |
1988年 | 221篇 |
1987年 | 215篇 |
1986年 | 231篇 |
1985年 | 218篇 |
1984年 | 206篇 |
1983年 | 200篇 |
1982年 | 222篇 |
1981年 | 230篇 |
1980年 | 183篇 |
1979年 | 139篇 |
1978年 | 133篇 |
1977年 | 140篇 |
1976年 | 113篇 |
1975年 | 112篇 |
1974年 | 102篇 |
1973年 | 97篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The management of patients with endoscopically removed malignant intestinal polyps is controversial. The risk of residual disease should be assessed against the risk of a surgical operation. The authors report 35 cases of malignant polyps (5.5% of 641 colonoscopically removed adenomas). Sixteen patients had carcinoma in situ and received no further treatment and 19 had invasive carcinoma (sessile in 6, pedunculated in 13). Of these 19, 7 did not undergo surgery--because of old age in 2, minimal invasion in 3, a low rectal location in 1 and refusal in 1. Twelve patients (3 with sessile, 9 with pedunculated polyps) underwent a surgical resection, and residual disease was present in 3 (25%), 1 with positive nodes. Reported criteria of increased risk of residual disease--cancer in lymphatics or veins, incomplete excision, tumour at resection margin, sessile and villous tumours--were present in nine. All three patients with residual disease had microscopically involved margins of resection. The authors believe that the increased risk of recurrence justifies the risk associated with subsequent surgical resection unless the patient is otherwise a poor operative risk. 相似文献
52.
Low molecular weight heparin compared with unfractionated heparin in prevention of postoperative thrombosis 总被引:2,自引:0,他引:2
M Samama P Bernard J P Bonnardot S Combe-Tamzali Y Lanson E Tissot 《The British journal of surgery》1988,75(2):128-131
Three consecutive randomized open studies have been carried out to determine the optimal dosage of low molecular weight heparin (LMWH) in the prevention of postoperative thrombosis in general surgery (892 patients). All patients undergoing abdominal, gynaecological, thoracic or urological surgery were over 40 years old and presented at least one of the following risk factors for thrombosis: previous thromboembolism, obesity, varicose veins, malignancy (30 per cent), pre-operative hospitalization over 5 days, oestrogen therapy, chronic cardiac disease or bronchitis. Isotopic venous thrombosis and bleeding complications were assessed after subcutaneous administration of a LMWH fragment (LMWH, Enoxaparine) or unfractionated heparin (UH). The three studies compared 3 X 5000 units UH daily with 1 X 60 mg, 1 X 40 mg, 1 X 20 mg LMWH daily. Thromboembolic events rates were not significantly different from group to group (UH: 3.8 per cent, 2.7 per cent, 7.6 per cent respectively compared with LMWH: 2.9 per cent, 2.8 per cent, 3.8 per cent). Bleeding episodes including wound haematoma formation, perioperative blood losses and systemic haemorrhage were not significantly different in patients receiving LMWH or UH. Significant decreases in haematocrit and haemoglobin were only observed in patients receiving 60 mg Enoxaparine (as compared to UH). An analysis using the 'intention to treat' approach gave results consistent with those of an analysis of good compliers. An overview of isotopic thromboses in the three studies gave no evidence of differences amongst the effects of the three doses of LMWH (P = 0.20), and pooling the results of the three studies using the Mantel-Haenszel procedure gave no evidence of a global difference between Enoxaparine and UH (P = 0.54). These results suggest that an optimal dosage of 20 mg/day of Enoxaparine is safe and effective in the prevention of postoperative thrombosis in this population. 相似文献
53.
Non-A Non-B Hepatitis and the Safety of Intravenous Immune Globulin, pH 4.2: A Retrospective Survey: 总被引:1,自引:0,他引:1
Ralph H. Rousell Robert A. Good Bernard Pirofsky and Richard I. Schiff 《Vox sanguinis》1988,54(1):6-13
Abstract. Evidence for transmission of non-A non-B hepatitis (NANB) was sought in 41 patients with primary immune deficiency who were receiving human intravenous immune globulin (IGIV) over periods ranging from 6 to 15 months at a monthly dosage of 400 mg/kg body weight. One lot of a reduced and alkylated IGIV and three lots of a nonmodified preparation stabilized at pH 4.2 were used. No evidence of NANB was found, although transient elevations in serum glutamic pyruvic transaminase (alanine aminotransferase) were found in 6 of the patients. The possible causes of the elevated levels in these 6 patients are discussed. 相似文献
54.
Diana A. Lepore Kenneth R. Knight Surajit Bhattacharya Morris Ritz Sonia P. Robbins Peter Sieg Wayne A. Morrison Bernard McC. O'Brien 《Microsurgery》1994,15(10):685-692
The chief aim of this study was to maximize flap survival by counteracting the pathophysiological changes occurring during ischemia-reperfusion. Rabbit epigastric skin flaps given 21 hours of ischemia were infused intra-arterially with selected drugs at the start of reperfusion. Compared with control infused ischemic flaps, which had a 33% survival rate on day 7 post-ischemia, significant improvement was found with vasodilators nitrendipine (61%) and prostacyclin (65%) and the thrombolytic agent urokinase (65%); marginal improvement with the free radical scavenger desferrioxamine (53%); but no change with streptokinase (44%), heparin (21%), and ATP-MgCl2 (35%). A drug mixture comprising all of these agents except streptokinase and urokinase produced 87% survival, suggesting an additive effect. Biochemical assays on skin homogenates and blood implicated oxygen free radicals, neutrophil infiltration, and thromboxane in flap failure. These results imply that multiple factors are responsible for ischemic flap failure and that a mixture of drugs needs to be infused to counteract all of the detrimental changes. © 1994 Wiley-Liss, Inc. 相似文献
55.
Linda G. Rabinowitz M.D. Nancy B Esterly M.D. Ilona J. Frieden M.D. Gregory S. Garbin M.D. Roy C. Grekin M.D. T. J. Stafford M.D. Ph.D. O. T. Tan M.D. Linda G. Rabinowitz M.D. Gerald N. Goldberg M.D. Karen F Rothman M.D. Lynne J. Roberts M.D. Roy G. Geronemus M.D. Susan B. Mallory M.D. Jerome M. Garden M.D. Joseph G. Morelli M.D. Moise L Levy M.D. Bernard A. Cohen M.D. 《Pediatric dermatology》1992,9(2):132-153
One of the most exciting developments in pediatric dermatology has been the use of the flashlamp-pumped, 585-nm, pulsed dye laser for treatment of vascular birthmarks. In many cases the results are miraculous. The increase in self-esteem and happiness of many children and adolescents has been overwhelming; for some, depression has been lifted, stuttering has ceased, social involvement has increased, and antidepressants have been discontinued. There are many success stories to tell.
Despite the remarkable effects of the pulsed dye laser and the medical and psychosocial indications for its use, the issue of pain control remains significant. We have no perfect outpatient pediatric anesthetic. Most methods carry either some risk or, if not hazardous, often are not very effective for controlling pain. Needless to say, a diversity of opinions exist on how to manage discomfort from this treatment modality. Therefore, we thought it would be useful to share the experiences and opinions of several dermatologists who have extensive experience with the pulsed dye laser. 相似文献
Despite the remarkable effects of the pulsed dye laser and the medical and psychosocial indications for its use, the issue of pain control remains significant. We have no perfect outpatient pediatric anesthetic. Most methods carry either some risk or, if not hazardous, often are not very effective for controlling pain. Needless to say, a diversity of opinions exist on how to manage discomfort from this treatment modality. Therefore, we thought it would be useful to share the experiences and opinions of several dermatologists who have extensive experience with the pulsed dye laser. 相似文献
56.
57.
In a patient with clinical manifestations suggestive of brain malformation, CT showed lissencephaly with absent opercularization. The child had seizures but not a typical EEG of hypsarhythmia. MRI confirmed the diagnosis and showed heterotopic grey matter and abnormal basal ganglia. High grey-white matter contrast and the possibility of imaging the brain in sagittal, coronal and transverse planes make MRI the methode of choice for the evaluation of lissencephaly and other brain malformations. 相似文献
58.
BALB/c mice were bilaterally implanted with bipolar electrodes either in anterodorsal (ADH) or posteroventral hippocampus (PVH) in order to compare the effects of postsession electrical stimulation on memory processes. For each experiment, 30 s after the end of the first session, the animals were stimulated during 80 s. For both hippocampal regions, the stimulation intensity was half of the afterdischarge threshold value. Control groups were naive, ADH and PVH implanted non-stimulated animals. Different appetitive and aversive tasks were used. Subseizure stimulation never created a deficit. Depending on the region of the hippocampus stimulated and on the learning task, a retention enhancement was eventually observed. These data are in agreement with the involvement of hippocampus in initial stages of memory consolidation. Further, the subseizure stimulation permitted a functional dissociation between the two hippocampal regions. Both regions seemed involved in the integration of information, but the anterodorsal part would be rather related to behavioral inhibition, while the posteroventral part would have the capacity to induce an arousal state allowing behavioral flexibility. 相似文献
59.
Elke Wezenberg Robert Jan Verkes Ge S F Ruigt Wouter Hulstijn Bernard G C Sabbe 《Neuropsychopharmacology》2007,32(6):1272-1283
Ampakines act as positive allosteric modulators of AMPA-type glutamate receptors and facilitate hippocampal long-term potentiation (LTP), a mechanism associated with memory storage and consolidation. The present study investigated the acute effects of farampator, 1-(benzofurazan-5-ylcarbonyl) piperidine, on memory and information processes in healthy elderly volunteers. A double-blind, placebo-controlled, randomized, cross-over study was performed in 16 healthy, elderly volunteers (eight male, eight female; mean age 66.1, SD 4.5 years). All subjects received farampator (500 mg) and placebo. Testing took place 1 h after drug intake, which was around Tmax for farampator. Subjects performed tasks assessing episodic memory (wordlist learning and picture memory), working and short-term memory (N-back, symbol recall) and motor learning (maze task, pursuit rotor). Information processing was assessed with a tangled lines task, the symbol digit substitution test (SDST) and the continuous trail making test (CTMT). Farampator (500 mg) unequivocally improved short-term memory but appeared to impair episodic memory. Furthermore, it tended to decrease the number of switching errors in the CTMT. Drug-induced side effects (SEs) included headache, somnolence and nausea. Subjects with SEs had significantly higher plasma levels of farampator than subjects without SEs. Additional analyses revealed that in the farampator condition the group without SEs showed a significantly superior memory performance relative to the group with SEs. The positive results on short-term memory and the favorable trends in the trail making test (CTMT) are interesting in view of the development of ampakines in the treatment of Alzheimer's disease and schizophrenia. 相似文献
60.
A unique example of a gingival salivary gland choristoma together with a gingival cyst is described in a human autopsy specimen of periodontal tissues. A choristoma is a tumor-like growth which is derived from primordial cells which have been displaced from their original tissue or organ. Only 6 other examples of the gingival salivary gland choristoma have been described in the world literature. 相似文献