首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17165篇
  免费   550篇
  国内免费   35篇
耳鼻咽喉   916篇
儿科学   513篇
妇产科学   1087篇
基础医学   2122篇
口腔科学   100篇
临床医学   921篇
内科学   3687篇
皮肤病学   194篇
神经病学   1823篇
特种医学   289篇
外科学   1274篇
综合类   60篇
一般理论   1篇
预防医学   1267篇
眼科学   556篇
药学   2405篇
中国医学   39篇
肿瘤学   496篇
  2024年   12篇
  2023年   86篇
  2022年   297篇
  2021年   463篇
  2020年   174篇
  2019年   281篇
  2018年   548篇
  2017年   376篇
  2016年   400篇
  2015年   357篇
  2014年   598篇
  2013年   888篇
  2012年   1058篇
  2011年   1303篇
  2010年   670篇
  2009年   302篇
  2008年   812篇
  2007年   1156篇
  2006年   1216篇
  2005年   1191篇
  2004年   1277篇
  2003年   1258篇
  2002年   1036篇
  2001年   459篇
  2000年   500篇
  1999年   302篇
  1998年   103篇
  1997年   26篇
  1996年   16篇
  1995年   20篇
  1994年   14篇
  1993年   14篇
  1992年   14篇
  1991年   13篇
  1990年   31篇
  1988年   14篇
  1987年   23篇
  1986年   21篇
  1985年   28篇
  1984年   24篇
  1983年   21篇
  1982年   23篇
  1981年   33篇
  1980年   22篇
  1979年   26篇
  1978年   31篇
  1977年   30篇
  1976年   18篇
  1975年   22篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The case of a 43 year old male with giant chest wall tumor weighing 9.6 kg verified as chondrosarcoma is described. The patient was treated by multiple (six times) surgical procedures including left costopleuropneumonectomy and left subclavian artery end-to-end anastomosis between 1998 and 2005. Despite the palliative character of surgery, he achieved long-term survival but finally refused next surgery due to the risk of left upper limb amputation and died a few months later.  相似文献   
22.
OBJECTIVE: The studies showing the superior characteristics of ITA graft and its impact on the clinical results of coronary artery surgery were performed with ITA harvested almost exclusively as a pedicle. This study assesses the impact of ITA skeletonization on its innervation and reactivity. METHODS: Segments of skeletonized and non-skeletonized ITA were stained with antibodies against protein S-100 to look for the presence of sympathetic nerve fibers. The functional studies were performed on segments of discarded human pedicled ITA that were divided into two 3mm rings, one skeletonized and another non-skeletonized. We compared concentration-effect relationships for the contraction to norepinephrine and endothelium-dependent relaxation to acetylcholine and bradykinin, as well as endothelium-independent relaxation to sodium nitroprusside in skeletonized and non-skeletonized segments of the same ITA. RESULTS: Skeletonized ITA was devoid of protein S-100 positive nerve fibers. It contracted stronger (maximal response 37.0+/-2.04 vs. 25.4+/-1.83mN (P<0.001)) and was twice as sensitive to norepinephrine: pD(2) 6.03+/-0.10 vs. 5.70+/-0.12 (P=0.035). The endothelium-dependent relaxation responses did not differ between skeletonized and non-skeletonized ITA rings. The skeletonized ITA rings appeared over 10 times more sensitive to sodium nitroprusside: pD(2) 6.66+/-0.20 vs. 5.59+/-0.37 (P=0.012)-potency ratio 11.61. The maximal responses did not differ significantly: 112.0+/-6.71 vs. 129.4+/-16.4% (P=0.33). CONCLUSIONS: Skeletonization results in sympathectomy of ITA. It has no effect on endothelium-dependent relaxation but increases reactivity of ITA to norepinephrine. This augmented response to alpha-agonist is small, in comparison with over a ten-fold increase in sensitivity to sodium nitroprusside. Pedicled and skeletonized ITA are functionally significantly different vessels when studied in vitro.  相似文献   
23.
This paper presents results of an in vitro investigation of the optical anisotropy of the human cornea. Computer controlled imaging polarimetry and the Jones formalism were used to investigate the distribution of the birefringence and the azimuth angle across the surface of 12 corneas taken from the corneal bank. Each map of the birefringence and the azimuth angle has no rotational symmetry and is different for each cornea. The minimal value of the birefringence always appears in the corneal centre and varies from 9 to 43 degrees for different corneas. Birefringence of the cornea increases monotonically more than one order in the direction of the corneal periphery. Close to the centre of the cornea the azimuth angle is almost constant and varies significantly away from the optical part of the cornea.  相似文献   
24.
One hundred temporal bones obtained from forensic autopsies were dissected to expose injured structures. Longitudinal fractures were present in 82%, transverse fractures in 11%, and mixed fractures in 7% of the cases. Facial canal injuries were present in almost half of the bones with longitudinal fractures (36/82), although cuts of the facial nerve stem were rarely encountered. Damages to the facial canal associated with longitudinal fractures were most frequently seen in the region of the geniculum. However, transverse fractures with facial canal involvement (7/11) most frequently occurred in the labyrinthine portion, causing a complete cut of the facial nerve. Injuries to the jugular bulb were also common (21/100) and associated with all types of temporal bone fractures. Observed damages to the auditory ossicles included disconnection of their joints or fractures of the malleus or stapes. Fractures of the incus were not observed. Injuries to the carotid canal were common (52/100), although an injury to the arterial wall was observed in only one specimen. The frequency and nature of damage in temporal bone fractures strictly reflect the type of fracture, especially in terms of facial nerve disorders: the most serious damage is observed with fractures that involve the otic capsule.  相似文献   
25.
The Avantage double mobility press-fit cup was devised by Dr. Bousquet in the 70's to bring reasonable response to a problem of recurrent dislocation after total hip arthroplasty. The cup is attached to the femoral head by a bipolar polyethylene liner. The polyethylene liner moves freely inside a shiny--polished metal cup. The angular range of motion before impingement is increased by the mobility of the liner. The double connection (cup-liner, liner-head) reduces the stress on the metal cup and improve the stability of the prosthesis. The solution has proved to be efficient in reducing dislocation risk and maintains at the same time the appropriate range of motion. Between January 2004 and November 2005, 113 hip arthroplasties in 108 women with use of the double mobility cup were performed. The cemented version of the Avantage cup was inserted in 15 patients (mean age--76.9 years). Uncemented, HA coated implant was used in 98 patients (with mean age of 55 years). The mean follow-up was 20.4 months. No one patient was lost to follow-up. No postoperative dislocation was observed during follow-up. There was no unwanted leg lengthening greater than 1 cm. The Avantage cup may be indicated in any primary total hip arthroplasty especially in those with increased risk of postoperative dislocations. This cup enables a correct balance of the hip without a need of the unwanted lengthening of the leg.  相似文献   
26.
N‐acyl‐dopamines are a novel class of biologically active lipids that have recently been identified in the brain and have the potential to interact with neural signaling pathways. This study seeks to determine the ability of N‐oleoyl‐dopamine, a synthetic amide of oleic acid and dopamine, to cross the blood brain barrier. We determined the tissue content of radioactivity in selected brain regions, in a short‐run study design, following injections of [3H]N‐oleoyl‐dopamine (0.4 µCi) into the internal carotid artery in the rat. These results were compared with intracarotid injections of [3H]dopamine and with intravenous injections of both radiolabeled compounds. The level of radioactivity was determined using liquid scintillation and was expressed as the percentage of its total dose injected per gram of tissue. We found that the 15‐min brain uptake of radioactivity, with no distinct regional variations, amounted to about 6% following the intracarotid [3H]N‐oleoyl‐dopamine, which was a significant 3–4‐fold increase over that following similar administration of [3H]dopamine. Intravenous injections of [3H]N‐oleoyl‐dopamine gave a much smaller yield of radioactivity in brain tissue samples which was still severalfold greater than that for intravenous [3H]dopamine. Qualitative thin‐layered chromatography screening showed the presence of unchanged N‐oleoyl‐dopamine in the brain following injections. We conclude that N‐oleoyl‐dopamine has an appreciable ability to cross the blood‐brain barrier, which contrasts the limited transfer of dopamine alone. N‐oleoyl‐dopamine might exert physiological effects due to its known affinity for the central vanilloid receptors or to better satisfying the brain tissue demand for dopamine. The study suggests a potential pharmacological role for N‐oleoyl‐dopamine delivered exogenously in helping regulate the brain function. Drug Dev. Res. 60:217–224, 2003. © 2003 Wiley‐Liss, Inc.  相似文献   
27.
In 30 patients on chronic haemodialysis treatment the platelet activity and function were studied before and during antiplatelet therapy with alpha-tocopherol and sulphinpyrazone. In both kinds of treatment a significant decrease of ADP-induced and spontaneous aggregation was observed. Sulphinpyrazone exerts an inhibitory effect not only on platelet aggregation but also on platelet factor 3 and provokes a significant prolongation of the bleeding time.  相似文献   
28.
29.
Nasopharyngeal angiofibromas occur predominantly in males in their puberty and adolescence; the incidence in other age groups and in women is exceptional. This report describes a case of a 57-year-old woman with nasopharyngeal angiofibroma presenting typical radiological findings in computed tomography, MR imaging and angiography. The tumour was successfully removed and histopathological examination confirmed the diagnosis. In 6 years follow-up the patient is free of symptoms.  相似文献   
30.
The situation of end-stage renal disease (ESRD) patients in central and eastern Europe was very poor for many years during the so called socialistic era. Economical and political liberation resulted in the significant growth of renal replacement facilities in this region. The number of hemodialysis units increased significantly (56%) during the period 1990–1996, and the number of patients treated with this modality has risen by 75%. More dramatic progress was achieved in peritoneal dialysis. The number of units performing this method of renal replacement therapy (RTT) increased by 277% and the number of patients by more than 300%. Not only quantitative but also qualitative changes were observed. More modern hemodialysis machines installed in the vast majority of units allow for the performance of bicarbonate dialysis, controlled ultrafiltration, and sodium profile modeling. Also, a wider choice of biocompatible dialyzers has become available during the last few years. The number of centers performing renal transplantation has increased significantly, but the number of renal transplants has not followed this progress. Despite all the progress, further development of all RRT methods is necessary to achieve acceptance rates comparable to those observed in developed countries.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号