全文获取类型
收费全文 | 41373篇 |
免费 | 2069篇 |
国内免费 | 170篇 |
专业分类
耳鼻咽喉 | 554篇 |
儿科学 | 838篇 |
妇产科学 | 509篇 |
基础医学 | 5328篇 |
口腔科学 | 1255篇 |
临床医学 | 2874篇 |
内科学 | 9484篇 |
皮肤病学 | 1041篇 |
神经病学 | 3830篇 |
特种医学 | 2014篇 |
外国民族医学 | 1篇 |
外科学 | 5868篇 |
综合类 | 171篇 |
一般理论 | 7篇 |
预防医学 | 1540篇 |
眼科学 | 889篇 |
药学 | 2735篇 |
中国医学 | 110篇 |
肿瘤学 | 4564篇 |
出版年
2023年 | 234篇 |
2022年 | 430篇 |
2021年 | 762篇 |
2020年 | 440篇 |
2019年 | 572篇 |
2018年 | 743篇 |
2017年 | 651篇 |
2016年 | 788篇 |
2015年 | 735篇 |
2014年 | 1024篇 |
2013年 | 1232篇 |
2012年 | 1947篇 |
2011年 | 2061篇 |
2010年 | 1244篇 |
2009年 | 1118篇 |
2008年 | 1797篇 |
2007年 | 2107篇 |
2006年 | 1928篇 |
2005年 | 1904篇 |
2004年 | 1912篇 |
2003年 | 1779篇 |
2002年 | 1772篇 |
2001年 | 1352篇 |
2000年 | 1442篇 |
1999年 | 1310篇 |
1998年 | 520篇 |
1997年 | 421篇 |
1996年 | 400篇 |
1995年 | 324篇 |
1994年 | 322篇 |
1993年 | 299篇 |
1992年 | 996篇 |
1991年 | 855篇 |
1990年 | 822篇 |
1989年 | 815篇 |
1988年 | 763篇 |
1987年 | 763篇 |
1986年 | 675篇 |
1985年 | 627篇 |
1984年 | 431篇 |
1983年 | 349篇 |
1979年 | 298篇 |
1978年 | 201篇 |
1977年 | 182篇 |
1974年 | 195篇 |
1973年 | 163篇 |
1972年 | 165篇 |
1971年 | 182篇 |
1970年 | 156篇 |
1969年 | 177篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
We present a patient with vertebrobasilar insufficiency, with vertigo and horizontal nystagmus, induced by turning the head to the right. Angiography demonstrated transient occlusion of the left vertebral artery at the atlantoaxial joint during rotation of the head. The pathogenesis and angiographic findings are discussed. 相似文献
62.
We investigated the involvements of sympathetic and nonadrenergic nervous systems in the inhibitory reflex following bronchoconstriction in dogs. Inhalations of a 0.00125% solution of histamine and Ascaris suum antigen (3 mg protein) to the bronchial side induced reflex tracheal constriction following bronchoconstriction. An intra-arterial infusion of 5 micrograms/min of atropine to the tracheal site changed the reflex tracheal constrictions by histamine and antigen inhalations into tracheal dilatations. The reflex tracheal dilatations were abolished by the combination of intra-arterial propranolol (100 micrograms) and transections of both the bilateral superior laryngeal nerves and the spinal cord at the C1 level. The reflex tracheal constrictions induced by histamine and antigen inhalations were increased with 100 micrograms propranolol. Furthermore, the reflex tracheal constrictions were enhanced by the combination of 100 micrograms propranolol and transection of the spinal cord. These findings indicate that during the constriction of the bronchial smooth muscle, not only a reflex tracheal constriction mechanism but also one of reflex dilatation operates and that the latter reflex response may be mainly mediated by the sympathetic nerves, with partial involvement of the nonadrenergic nerves. This inhibitory reflex may attenuate asthmatic bronchoconstriction. 相似文献
63.
K Takayasu Y Muramatsu N Moriyama S Yamazaki T Takayama S Hirohashi Y Shimamura A Takahashi 《Journal of computer assisted tomography》1992,16(2):212-215
To differentiate focal nodular hyperplasia (FNH) from other hepatic tumors, especially hepatocellular carcinoma, we evaluated the hemodynamics of histologically proved FNH in three patients, two by arterial angio-CT and one by microangiography of the resected specimen. These studies demonstrated the centrifugal blood supply of FNH (early filling of central tumor vessels radiating to periphery, and lobulated tumor stains with central low density area in the late phase), which could not be demonstrated by dynamic CT or hepatic angiography. Arterial angio-CT is useful as a further study, when differential diagnosis of FNH is uncertain by other imaging techniques. 相似文献
64.
Susumu Ishikawa M.D. Akio Ohtaki M.D. Toru Takahashi M.D. Tetsuya Koyano M.D. Yutaka Hasegawa M.D. Satoshi Ohki M.D. Yukitaka Isa M.D. Kennichi Arai M.D. Fumio Kunimoto M.D. Yasuo Morishita M.D. 《Journal of cardiac surgery》1997,12(3):176-179
A bstract The purpose of this study was to assess the efficacy of nasal mask bi-level positive airway pressure (BiPAP) support in managing respiratory failure following cardiovascular surgery. A total of 20 patients requiring postoperative prolonged respiratory support of 72 hours or longer were studied. BiPAP support was used for eight patients (BiPAP group); the other 12 patients were managed using ordinary oxygen mask treatment (control group). The mean age of the BiPAP group and control group was 65 and 58 years of age, respectively. The mean period of postoperative endotracheal intubation of the BiPAP group and control group was 12 ± 5 days and 7 ± 1 days, respectively. Reintubation was necessary in two patients of the control group. The BiPAP group patients required no reintubation. BiPAP support was discontinued within 48 hours in 6 out of 8 patients. The respiratory rates of control group increased (p < 0.1) 24 hours after extubation, however, the respiratory rates of the BiPAP group remained unchanged. The values of the respiratory index of the BiPAP group improved significantly (p < 0.01) after BiPAP management (from 1.5 ± 0.2 to 0.9 ± 0.2). The values of the control group, however, remained unchanged. A-aDO2 and Qs/Qt decreased (p < 0.1) in the BiPAP group. There were no significant differences in central venous pressure or circulatory status between the two groups. In conclusion, BiPAP support is a noninvasive management technique for postoperative respiratory failure and may also prevent prolonged endotracheal intubation. 相似文献
65.
We reported movement-related cortical potentials (MRCPs) in 11 patients with lesion of the dentate nucleus (Machado-Joseph disease (MJD) 7 cases, dentato-rubro-pallido-luysian atrophy (DRPLA)1, myoclonus epilepsy associated with ragged-red fibers (MERRF)1, dyssynergia cerebellaris myoclonica (DCM) 2), and compared with those of 7 cases of multiple system atrophy (MSA) who were postulated to have mild dentate lesions (striato-nigral degeneration 2 cases, Shy-Drager syndrome 2, sporadic olivo-ponto-cerebellar atrophy 3), and 7 control subjects without any neurological findings. Further we classified the diseases into the following two groups based on the lesion of the dentate nucleus. One was MJD group that had normal or slightly abnormal electroencephalogram (EEG), and the other was DN group (DRPLA, MERRF, DCM) that had markedly abnormal EEG. One of the main findings from this study was smaller slope of the Ns' in the MJD and DN group and normal slope of BP. There was no significant difference in the slope of Ns' between MJD patients and DN patients. This result shows EEG abnormalities have no influence on MRCP recordings. These results suggest that Ns' component may reflect the function in the cerebellar dentate nucleus, and that MRCP is a useful diagnostic method in patients with cerebellar ataxia. 相似文献
66.
W A Gomes F A Lado N C de Lanerolle K Takahashi C Pan H P Hetherington 《Magnetic resonance in medicine》2007,58(2):230-235
Reduced hippocampal N-acetyl aspartate (NAA) is commonly observed in patients with advanced, chronic temporal lobe epilepsy (TLE). It is unclear, however, whether an NAA deficit is also present during the clinically quiescent latent period that characterizes early TLE. This question has important implications for the use of MR spectroscopic imaging (MRSI) in the early identification of patients at risk for TLE. To determine whether NAA is diminished during the latent period, we obtained high-resolution (1)H spectroscopic imaging during the latent period of the rat pilocarpine model of human TLE. We used actively detuneable surface reception and volume transmission coils to enhance sensitivity and a semiautomated voxel shifting method to accurately position voxels within the hippocampi. During the latent period, 2 and 7 d following pilocarpine treatment, hippocampal NAA was significantly reduced by 27.5 +/- 6.9% (P < 0.001) and 17.3 +/- 6.9% (P < 0.001) at 2 and 7 d, respectively. Quantitative estimates of neuronal loss at 7 d (2.3 +/- 7.7% reduction; P = 0.58, not significant) demonstrate that the NAA deficit is not due to neuron loss and therefore likely represents metabolic impairment of hippocampal neurons during the latent phase. Therefore, spectroscopic imaging provides an early marker for metabolic dysfunction in this model of TLE. 相似文献
67.
68.
Makoto Ishitobi Yasuo Miyoshi Akiko Ando Seiichi Hasegawa Chiyomi Egawa Yasuhiro Tamaki Morito Monden Shinzaburo Noguchi 《Clinical cancer research》2003,9(4):1376-1380
PURPOSE: The association of BRCA2 polymorphisms at codon 372 [Asn (N)/His (H)]and codon 784 [Met (M)/Val (V)] with breast cancer risk was evaluated in Japanese women. In addition, the prognostic significance of these polymorphisms was studied in breast cancer patients. EXPERIMENTAL DESIGN: A case-control study was conducted to examine the association of the BRCA2 N/H372 polymorphism and M/V 784 polymorphism with breast cancer risk (cases = 149, controls = 154). The prognostic significance of these polymorphisms was evaluated in 139 patients with primary breast cancer. RESULTS: No significant association was observed between the N/H372 polymorphism and breast cancer risk. In contrast, a significant increase in breast cancer risk (odds ratio, 2.03; 95% confidence interval, 1.07-3.87) was observed in carriers of the variant allele (V784) of the M/V784 polymorphism as compared with noncarriers after adjustment for the classical risk factors, age, family history, parity, body mass index, and so forth. Among breast cancer patients, various clinicopathological parameters including menopausal status, tumor size, lymph node status, histological grade, and estrogen-receptor status were not significantly different between the carriers and noncarriers of the variant allele with regard to both N/H372 and M/V784 polymorphisms. The N/H 372 polymorphism was not significantly associated with patient prognosis. On the other hand, breast cancer patients carrying the variant allele of M/V784 polymorphism showed a significantly (P = 0.014) lower 3-year disease-free survival rate (63%) than noncarriers (92%). Multivariate analysis has revealed that the M/V784 polymorphism is a significant prognostic factor, being independent of the other conventional prognostic factors such as lymph node status and estrogen receptor status. CONCLUSION: These results suggest that the M/V784 polymorphism, but not the N/H372 polymorphism, would be useful in the selection of women at high risk for developing breast cancer and would also serve as a clinically useful prognostic factor in breast cancer patients. 相似文献
69.
Masahito Minakawa Kenji Takahashi Norihiro Kondo Masaharu Hatakeyama Toshihiko Kuga Ikuo Fukuda 《The Japanese Journal of Thoracic and Cardiovascular Surgery》2003,51(11):582-587
Objective: Reoperative coronary bypass grafting is at high risk. Particularly in redo cases where the patent graft is running near
the midline of the sternum, the graft may be exposed to injury by a median sternotomy and subsequent dissection. Whereas,
off-pump bypass grafting from the left axillary artery or descending thoracic artery by a left thoracotomy approach is safe
for preventing graft damage.Methods: From March 1998 to February 2002, we performed off-pump coronary artery bypass grafting by a left thoracotomy approach in
9 patients. The left axillary artery was used as the inflow vessel in 4 cases, and the descending thoracic, aorta in 5.Results: The radial artery was anastomosed proximally to the axillary artery in 4 cases and the descending thoracic aorta in one
case. The saphenous vein graft was anastomosed, proximally to the descending thoracic aorta in 4 cases. Transdiaphragmatic
minimally invasive bypass grafting for the right coronary artery was simultaneously performed in 3 cases. Postoperative cardiac
events were ventricular arrhythmia in 6 cases and supraventricular arrhythmia in 3 cases. There was no damage to the patent
grafts. Postoperative coronary angiography performed, in 8 cases revealed all the grafts to be patent without stenosis. Cardiac
symptoms were not found after the operation in any of the cases.Conclusions: These procedures can prevent the injury to patent grafts caused by a median sternotomy, and will be one of the useful strategies
for reoperative off-pump coronary artery bypass grafting. 相似文献
70.