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   931篇
  免费   43篇
  国内免费   9篇
耳鼻咽喉   45篇
儿科学   47篇
妇产科学   59篇
基础医学   75篇
口腔科学   37篇
临床医学   87篇
内科学   148篇
皮肤病学   24篇
神经病学   73篇
特种医学   43篇
外科学   198篇
综合类   21篇
预防医学   22篇
眼科学   48篇
药学   41篇
中国医学   2篇
肿瘤学   13篇
  2023年   7篇
  2022年   15篇
  2021年   26篇
  2020年   11篇
  2019年   22篇
  2018年   22篇
  2017年   24篇
  2016年   32篇
  2015年   39篇
  2014年   36篇
  2013年   54篇
  2012年   68篇
  2011年   80篇
  2010年   39篇
  2009年   38篇
  2008年   65篇
  2007年   75篇
  2006年   70篇
  2005年   72篇
  2004年   58篇
  2003年   47篇
  2002年   31篇
  2001年   12篇
  2000年   7篇
  1999年   7篇
  1998年   3篇
  1997年   2篇
  1996年   6篇
  1995年   3篇
  1993年   2篇
  1992年   4篇
  1990年   4篇
  1986年   1篇
  1969年   1篇
排序方式: 共有983条查询结果,搜索用时 0 毫秒
1.
BACKGROUND: Patients with allergic rhinitis and bronchial hyperresponsiveness (BHR) may be at higher risk of developing asthma. OBJECTIVE: To investigate whether reactivity to aeroallergens in skin prick testing (SPT) and serum eosinophil cationic protein levels can be used to predict BHR in allergic rhinitis patients. METHODS: Fifty-nine consecutive patients with allergic rhinitis underwent SPTs using grass, tree, weed, parietaria, Alternaria, Aspergillus, mites, and cat and dog dander extracts. Methacholine challenge tests were performed using spirometry. RESULTS: Methacholine-induced BHR was detected in 23 patients (39%). Of 59 patients, 14 had 1 positive SPT response, 35 had 2 to 4 positive responses, and 10 had more than 4 positive responses. There was a significant inverse correlation between methacholine provocation concentration that caused a decrease in forced expiratory volume in 1 second of 20% (PC20) and the number of positive SPT responses (r = -0.28; P = .03). The BHR-positive patients had a mean of 4 positive SPT responses, whereas BHR-negative patients had a mean of 2.6 (P = .04). Nine BHR-positive patients (39%) and only 1 BHR-negative patient (3%) had more than 4 positive SPT responses (P < .001). There was no correlation between serum eosinophil cationic protein levels and methacholine PC20 doses. There was a strong association between hyperresponsiveness to methacholine and both cat and dog dander sensitivity (P < .001 and P = .001, respectively). CONCLUSIONS: Allergic rhinitis patients with SPT responses to a higher number of allergens are more likely to have BHR. Whether the number of positive SPT responses correlates with the risk of developing asthma in allergic rhinitis patients remains to be determined.  相似文献   
2.
The purpose of this investigation was to describe the neural constraints on three-dimensional (3-D) orientations of the eye in space (Es), head in space (Hs), and eye in head (Eh) during visual fixations in the monkey and the control strategies used to implement these constraints during head-free gaze saccades. Dual scleral search coil signals were used to compute 3-D orientation quaternions, two-dimensional (2-D) direction vectors, and 3-D angular velocity vectors for both the eye and head in three monkeys during the following visual tasks: radial to/from center, repetitive horizontal, nonrepetitive oblique, random (wide 2-D range), and random with pin-hole goggles. Although 2-D gaze direction (of Es) was controlled more tightly than the contributing 2-D Hs and Eh components, the torsional standard deviation of Es was greater (mean 3.55 degrees ) than Hs (3.10 degrees ), which in turn was greater than Eh (1.87 degrees ) during random fixations. Thus the 3-D Es range appeared to be the byproduct of Hs and Eh constraints, resulting in a pseudoplanar Es range that was twisted (in orthogonal coordinates) like the zero torsion range of Fick coordinates. The Hs fixation range was similarly Fick-like, whereas the Eh fixation range was quasiplanar. The latter Eh range was maintained through exquisite saccade/slow phase coordination, i.e., during each head movement, multiple anticipatory saccades drove the eye torsionally out of the planar range such that subsequent slow phases drove the eye back toward the fixation range. The Fick-like Hs constraint was maintained by the following strategies: first, during purely vertical/horizontal movements, the head rotated about constantly oriented axes that closely resembled physical Fick gimbals, i.e., about head-fixed horizontal axes and space-fixed vertical axes, respectively (although in 1 animal, the latter constraint was relaxed during repetitive horizontal movements, allowing for trajectory optimization). However, during large oblique movements, head orientation made transient but dramatic departures from the zero-torsion Fick surface, taking the shortest path between two torsionally eccentric fixation points on the surface. Moreover, in the pin-hole goggle task, the head-orientation range flattened significantly, suggesting a task-dependent default strategy similar to Listing's law. These and previous observations suggest two quasi-independent brain stem circuits: an oculomotor 2-D to 3-D transformation that coordinates anticipatory saccades with slow phases to uphold Listing's law, and a flexible "Fick operator" that selects head motor error; both nested within a dynamic gaze feedback loop.  相似文献   
3.
Chondrosarcoma is a rare tumor. In this study, we present a case with laryngeal chondrosarcoma that was treated by an endolaryngeal approach using an operation microscope. The patient remains disease-free to date, with no evidence of new or recurrent disease more than 3 years after the endolaryngeal surgery. The computerized tomography and endoscopic examinations did not reveal any recurrent disease, indicating the success of the endolaryngeal approach.  相似文献   
4.
We wanted to investigate the effect of misoprostol administered vaginally before operative hysteroscopy on cervical dilation, complications, and failure rates in patients who have undergone cesarean section and who have never delivered vaginally. Sixty patients who had undergone cesarean section, who had never delivered vaginally before, and were about to undergo hysteroscopy for various intrauterine lesions were included in this randomized controlled study. Thirty-two patients in the study group were given misoprostol 400 microg, and 28 patients in the control group were given placebo (hexetidine pill) vaginally twice, 6 and 12 hours before the procedure. Primary endpoints were cervical width detected with Hegar dilators and complication and failure rates. Mean cervical width was greater in patients in the study group (6.5 +/- 0.8) than it was in patients in the control group (3.0 +/- 0.6), (p = .0001). Complication and failure rates were lower in patients in the study group (p = .01). Administration of vaginal misoprostol before hysteroscopy proved to be effective in cervical ripening and in reducing complication and failure rates.  相似文献   
5.
The aim of this study was to examine prenatal diagnosis of double-outlet right ventricle (DORV)-associated anomalies and prognosis of each case. Medical records were reviewed of fetuses with DORV who had fetal echocardiography at our institution from 2002 to 2006. Pre- and postnatal diagnosis and outcome were compared and evaluated. Twenty-one fetuses were diagnosed with DORV. The pregnancy was terminated in seven cases. Three cases had chromosomal abnormalities; three cases, hypoplastic left ventricle; and one case, encephalocele. Accurate prenatal diagnosis of the ventricular septal defect, outflow obstruction, and great artery relationship was achieved in 14 of 16 cases (87.5%). Only 2 of 13 live-born cases survived beyond 6 months. The overall prognosis for fetuses with DORV is poor. DORV is found in fetuses with a huge spectrum of associated cardiac and extracardiac anomalies. Careful assessment by fetal echocardiography can determine important anatomic details with adequate correctness for precise counseling.  相似文献   
6.
Objectives We aimed to determine associated ultrasonographic findings, chromosome abnormalities and the prognostic factors of cystic hygromas in live-born infants. Methods We reported a series of 57 cystic hygroma cases, who were diagnosed in the first and the second trimester of pregnancy by means of the ultrasonographic morphology of cystic hygroma, associated structural abnormalities, karyotype analysis and the autopsy findings. Survivors were followed for their fetal outcome and prognosis. Results There were 57 new cases of cystic hygroma among 8,155 screenings (0.7%). 35 of the cases (61.4%) were nonseptated and 22 of the cases (38.6%) were septated cystic hygroma. Chromosomal abnormalities were found in 23 of the cases (40.3%). The most common abnormality in nonseptated cystic hygroma was trisomy 21 (8 cases, 25%) and in septated cystic hygroma was Turner syndrome (4 cases, 21.1%). The most common associated structural malformations were cardiac abnormalities (in 7 cases, 20%) in nonseptated cystic hygroma cases and nonimmune hydrops (in 12 cases, 54.5%) in septated cystic hygroma cases. Overall survival was poor; only one case of septated cystic hygroma with axillary location and seven cases of nonseptated cystic hygroma, of whom two died in the neonatal period, were alive (10.5%). This study had 80% power to detect 0.03% difference in diagnosis cystic hygroma (α = 0.05, β = 0.80). Conclusion Fetuses with cystic hygroma are at high risk for adverse outcome. Prenatal diagnosis with invasive procedures should be done in order to inform the parents in detail. Axillary location of the hygroma and the depth of invasion had prognostic importance.  相似文献   
7.
8.
Metabolic Brain Disease - Gaucher disease type 2 is the most progressive and the rarest form of Gaucher disease, defined as the acute neuronopathic type. We presented two GD2 patients who died...  相似文献   
9.
10.
Background:Polycystic ovary syndrome (PCOS) is the most common endocrine-metabolic disease in women in reproductive age, and occurs in one of 10 women. The disease includes menstrual irregularity and excess of male hormones and is the most common cause of female infertility. Dyspnea is a frequent symptom and is often thought to be due to obesity, and whether it is due to cardiac dysfunction is unknown.Objective:To evaluate right ventricle-pulmonary artery (RV-PA) coupling and pulmonary arterial stiffness in patients with PCOS.Methods:44 PCOS patients and 60 controls were included; venous blood samples were taken for laboratory tests and 2-D, m-mode and tissue doppler transthoracic echocardiography were performed for all the participants. P<0,05 was considered as statistically significant.Results:When compared to the control group, PCOS patients had higher pulmonary artery stiffness values (p=0,001), which were positively correlated with HOMA-IR (r=0,545 and p<0,001). RV-PA coupling was also impaired in 34% of the study patients.Conclusion:Pulmonary artery stiffness is increased and RV-PA coupling is impaired in patients with PCOS. (Arq Bras Cardiol. 2021; 116(4):806-811)Palavras-chave: Diseases of the Endocrine System, Arterial Stiffness, Female infertility, Obesity, Dyspnea, Pulmonary hypertension  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