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   9090篇
  免费   492篇
  国内免费   66篇
耳鼻咽喉   107篇
儿科学   211篇
妇产科学   65篇
基础医学   1096篇
口腔科学   208篇
临床医学   602篇
内科学   2721篇
皮肤病学   120篇
神经病学   662篇
特种医学   303篇
外科学   1579篇
综合类   61篇
预防医学   280篇
眼科学   145篇
药学   551篇
中国医学   15篇
肿瘤学   922篇
  2023年   76篇
  2022年   107篇
  2021年   217篇
  2020年   117篇
  2019年   141篇
  2018年   215篇
  2017年   169篇
  2016年   170篇
  2015年   217篇
  2014年   257篇
  2013年   293篇
  2012年   448篇
  2011年   546篇
  2010年   303篇
  2009年   266篇
  2008年   460篇
  2007年   501篇
  2006年   494篇
  2005年   455篇
  2004年   499篇
  2003年   458篇
  2002年   477篇
  2001年   199篇
  2000年   193篇
  1999年   201篇
  1998年   108篇
  1997年   113篇
  1996年   95篇
  1995年   75篇
  1994年   92篇
  1993年   64篇
  1992年   147篇
  1991年   131篇
  1990年   150篇
  1989年   135篇
  1988年   111篇
  1987年   120篇
  1986年   86篇
  1985年   85篇
  1984年   63篇
  1983年   54篇
  1982年   40篇
  1981年   28篇
  1979年   54篇
  1978年   40篇
  1977年   34篇
  1974年   39篇
  1973年   39篇
  1972年   40篇
  1971年   34篇
排序方式: 共有9648条查询结果,搜索用时 0 毫秒
71.
Platelet aggregation is one of the most important mechanisms for acute myocardial infarction during exercise. We sought to evaluate the effect of ticlopidine (TP) on platelet aggregation (PA) during exercise in patients with ischemic heart disease (IHD). We studied 38 patients with IHD, 26 patients with effort angina pectoris, and 12 patients with a previous myocardial infarction. In protocol I, subjects were divided into two groups. Drugs altering platelet aggregation were withheld 2-4 weeks before the study in 25 patients (control group). TP (200 mg/day) was administered for 7 days in 13 patients (ticlopidine group). A symptom-limited modified Bruce protocol treadmill exercise test was performed. PA was measured at rest and after exercise by using optical densitometry induced by adenosine diphosphate (ADP). PA ratio (percentage of maximum) was compared. In protocol II, in 12 patients, treadmill exercise test and PA measurement were performed with and without TP. PA significantly increased after exercise in control (from 51.7+/-23.3% to 64.4+/-27.7%, p < 0.01) and ticlopidine (from 31.9+/-10.5% to 42.0+/-20.4%, p < .01) groups; however, its grade was lower in the ticlopidine group than in the control group. After exercise, PA was lower in the ticlopidine group than in control group (42.0+/-20.4% vs. 64.4+/-27.7%; p < 0.01). In the same patients, PA was lower with TP than without TP after exercise. Treadmill exercise-tolerance time was greater in the ticlopidine group than in the control group, but not statistically significant (762.3+/-139.2 vs. 711.6+/-169.6 s; NS). Exercise-tolerance time was significantly greater with TP than without TP in same patient (791.7+/-98.9 vs. 733.3+/-152.8 s; p < .05). TP suppressed the increase of PA during exercise and increased the exercise-tolerance time in patients with IHD.  相似文献   
72.
Background: Basic fibroblast growth factor (bFGF) stimulates the mitogenesis of various cells and plays a key role in wound repair. We studied the immunohistochemical localization of bFGF during wound repair in the rat retina after laser photocoagulation. Methods: Krypton laser photocoagulation was performed on the eyes of pigmented rats. The eyes were enucleated on days 1, 3, 7, 14 and 28 after the photocoagulation, and the immunohistochemical localization of bFGF was assessed. Two different monoclonal antibodies and one polyclonal antibody against bFGF as first antibodies were used. Results: Marked immunoreactivity for bFGF was found in the ganglion cell layer, and weak immunoreactivity for bFGF was found in the retinal pigment epithelial (RPE) cells of the normal adult rat retina. On day 3 after laser photocoagulation, the nuclei and cytoplasm of proliferating RPE cells at the center of the photocoagulated lesion showed intense bFGF immunoreactivity. The nuclei of RPE cells around the lesion showed intense bFGF immunoreactivity. Macrophages that migrated into the lesion showed positive staining for bFGF. These immunoreactivity decreased with time. Controls (0.05 M Tris-HCl buffer, normal serum, or these same antibodies preabsorbed with bFGF) did not show positive staining. Conclusion: The finding of an elevated expression of bFGF immunoreactivity in the photocoagulated lesion suggests that bFGF may play a role in wound repair in the rat retina after laser photocoagulation.  相似文献   
73.
Key words  airway management - difficult intubation - Hallermann-Streiff syndrome  相似文献   
74.
75.
In order to clarify the characteristics of epilepsy in patients with severe mentally retarded (SMR) subjects, we analyzed 52 SMR subjects with epilepsy from the institute for SMR subjects at Kikuchi National Hospital, Kumamoto, Japan. A total of 61.5% patients had uncontrolled seizures which were resistant to treatment. The most common combinations of seizure types in those not responding to conventional anticonvulsants were generalized tonic-clonic seizures (GTCS) with tonic seizure and GTCS with atypical absence. Their clinical features were characterized by spastic paralysis associated with a slower background electroencephalogram and abnormal computed tomography scans of the head, suggesting the involvement of cortical damage. These findings suggest that a large proportion of epilepsy in SMR subjects does not respond to treatment and that the severity of organic brain damage may therefore affect the natural course of epilepsy in such patients.  相似文献   
76.
De novo uterine sarcoma with good response to neo-adjuvant chemotherapy   总被引:3,自引:0,他引:3  
Abstract.  Numa F, Umayahara K, Ogata H, Nawata S, Sakaguchi Y, Emoto T, Kawasaki K, Hirakawa H, Sase M, Oga A, Kato H. De novo uterine sarcoma with good response to neoadjuvant chemotherapy. We report here the extremely rare case of a 28-year-old woman with advanced stage uterine sarcoma arising soon after a cesarean section. She underwent an abdominal cesarean section because of a breech presentation. At the time of the procedure, there were no abnormal findings such as leiomyoma of the uterus in the abdominal cavity. One year later, she was referred to our hospital because of a large abdominal tumor. Transabdominal power Doppler ultrasonography and magnetic resonance imaging (MRI) showed a large hypervascular tumor in the abdominal cavity. Her serum levels, for the two tumor markers carbohydrate antigen CA125 and LDH, were elevated, at 219 U/ml (< 35 U/ml) and 862 IU/l (115 U/ml−217 U/ml), respectively. On the basis of a diagnosis of malignant tumor of gynecological origin, exploratory laparotomy was performed, and through biopsy, the tumor was found to be advanced undifferentiated uterine sarcoma. She exhibited a good response to neoadjuvant chemotherapy consisting of cisplatin, epirubicin, and dimethyltriazenoimidazole carboxamide (DTIC) every 28 days, which was successfully followed by a hysterectomy.  相似文献   
77.
The purpose of this study was to evaluate the effects of ebastine and terfenadine on the electrocardiogram of conscious dogs and cats. In dogs, terfenadine at oral doses of 30 mg/kg twice a day for 7 days prolonged the electrocardiographic QT interval and the corrected QT (QTc) interval on the seventh day, whereas the drug did not affect these parameters on the first day. Plasma concentrations of terfenadine and its active metabolite, fexofenadine, reached 306 and 8,541 ng/mL, respectively, on the seventh day. Ebastine at oral doses of 30 and 100 mg/kg once a day for 7 days was without effect on the QT and QTc intervals, whereas the drug slightly shortened the RR interval. On the seventh day following the dose of 100 mg/kg, plasma concentrations of ebastine and its active metabolite, carebastine, reached 36 and 1,939 ng/mL, respectively. In conscious cats, terfenadine at oral doses of 30 mg/kg twice a day for 7 days prolonged the QT and QTc intervals, QRS duration, JT and the corrected JT intervals. Unexpectedly, terfenadine induced ventricular tachyarrhythmia and premature beats. On the other hand, ebastine at oral doses of 100 mg/kg once a day for 7 days was without effect on the electrocardiographic parameters in cats. These results suggest that the electrocardiographic changes indicative of the proarrhythmic potential of terfenadine can be evaluated in conscious dogs and especially in conscious cats by repeated oral administration, and that ebastine does not induce such changes. 58:209–217, 2003. © 2003 Wiley‐Liss, Inc.  相似文献   
78.
We herein describe thallium-201 single photon emission tomography (T1-201 SPECT) findings in three cases with intracranial angioma. One of the lesions which was associated with chronic encapsulated intracerebral hematoma showed moderate accumulation of T1-201, but, others demonstrated no accumulation. The usefulness and limitations of T1-201 SPECT in differential diagnosis of intracranial mass lesions are discussed.  相似文献   
79.
80.
PURPOSE: The F-box protein S-phase kinase-associated protein 2 (Skp2) is one of the positive regulators of the cell cycle that promote ubiquitin-mediated proteolysis of the cyclin-dependent kinase inhibitor p27. In this study, we investigated the significance of Skp2 expression in human non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Clinicopathologic features and immunohistochemical expression of Skp2 and p27 proteins were studied in 138 patients with NSCLC. Survival analyses were performed using the Kaplan-Meier method and the Cox regression model. To analyze the role of Skp2 in vitro, NSCLC cells were transfected with an Skp2-expressing vector or small interfering RNA. RESULTS: Skp2 was overexpressed in males, smokers, patients with squamous cell carcinomas, and patients with poorly differentiated cancers (P = .034, < .0001, < .0001, and .002, respectively). The multivariant analysis revealed that Skp2 expression is an independent prognostic factor for survival in NSCLC. An inverse relationship of Skp2 with p27 expression was observed (P = .012), and patients with both a higher expression of Skp2 and a lower expression of p27 showed a significantly unfavorable prognosis (P = .0002). In vitro ectopic expression of Skp2 in NSCLC cells reduced the protein level of p27. Conversely, induction of Skp2 siRNA increased the protein level of p27, leading to growth inhibition in NSCLC cells. CONCLUSION: Skp2 overexpression is closely associated with the suppression of p27 and the aggressiveness in NSCLC. It also could be a therapeutic target in NSCLC.  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