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   1103篇
  免费   49篇
  国内免费   17篇
耳鼻咽喉   22篇
儿科学   13篇
妇产科学   7篇
基础医学   134篇
口腔科学   34篇
临床医学   85篇
内科学   275篇
皮肤病学   8篇
神经病学   144篇
特种医学   88篇
外科学   193篇
综合类   5篇
预防医学   33篇
眼科学   19篇
药学   59篇
中国医学   1篇
肿瘤学   49篇
  2023年   10篇
  2022年   16篇
  2021年   28篇
  2020年   14篇
  2019年   10篇
  2018年   24篇
  2017年   16篇
  2016年   22篇
  2015年   19篇
  2014年   29篇
  2013年   28篇
  2012年   41篇
  2011年   42篇
  2010年   17篇
  2009年   22篇
  2008年   27篇
  2007年   36篇
  2006年   59篇
  2005年   61篇
  2004年   48篇
  2003年   56篇
  2002年   70篇
  2001年   48篇
  2000年   40篇
  1999年   43篇
  1998年   12篇
  1997年   16篇
  1996年   14篇
  1995年   7篇
  1993年   6篇
  1992年   26篇
  1991年   32篇
  1990年   21篇
  1989年   36篇
  1988年   21篇
  1987年   25篇
  1986年   16篇
  1985年   15篇
  1984年   9篇
  1983年   8篇
  1982年   6篇
  1979年   8篇
  1978年   7篇
  1974年   6篇
  1973年   4篇
  1972年   4篇
  1970年   4篇
  1969年   4篇
  1968年   6篇
  1966年   6篇
排序方式: 共有1169条查询结果,搜索用时 15 毫秒
11.
The pathophysiology of altitude-related disorders in untrained trekkers has not been clarified. In the present study, the effects of workload on cardiovascular parameters and regional cerebral oxygenation were studied in untrained trekkers at altitudes of 2700 m and 3700 m above sea level. We studied 6 males and 4 females at each altitude, and their average ages were 31.3+/-7.1 y at 2700 m and 31.2+/-6.8 y at 3700 m, respectively. The resting values of heart rate and mean blood pressure were not significantly different at 2700 m and 3700 m than at sea level. However, increases in these values after exercise were more prominent at high altitudes (heart rate increase = 51.6% at 2700 m and 70.4% at 3700 m; mean blood pressure increase: 19.0% at 2700 m and 17.2% at 3700 m). In addition, post-exercise blood lactate concentration was significantly higher at 3700 m than at sea level or at 2700 m (i.e., 7.6 mM at 3700 m, 3.8 mM at 2700 m, and 4.17 mM at 0 m, respectively). Exercise induced an acute reduction in the arterial oxygen saturation value (SpO2) at 2700 m and 3700 m (i.e., 11.2% reduction at 2700 m and 9.4% at 3700 m), whereas no changes were observed at sea level. The resting values of regional oxygen saturation (rSO2)--measured by a near infra-red spectrophotometer at sea level, 2700 m, and 3700 m-were nearly identical. Exercise at sea level did not reduce this value. In contrast, we observed a decrease in rSO2 after subjects exercised at 2700 m and 3700 m (i.e., 26.9% at 2700 m and 48.1% at 3700 m, respectively). The rSO2 measured 2 min and 3 min after exercise at 3700 m was significantly higher than the preexercise value. From these observations, we concluded that alterations in cardiovascular parameters were apparent only after an exercise load occurred at approximately 3000 m altitude. Acute reduction in cerebral regional oxygen saturation might be a primary cause of headache and acute mountain sickness among unacclimatized trekkers.  相似文献   
12.
The relationship between the appearance of Islet-1-expressing cells and the longitudinal growth of primary afferent axons (PAAs) in the dorsal spinal cord of chick embryos was examined. Islet-1-expressing cells first appeared in the dorsal spinal cord at embryonic days (E) 3-3.5. These immunoreactive cells were aligned in a longitudinal column in close proximity to longitudinally elongating PAAs in the presumptive dorsal funiculus. By E8, when many PAAs invade the spinal gray matter, Islet-1-expressing cells had disappeared in the dorsal spinal cord. Following the dorsoventral rotation of the spinal cord in ovo before the invasion of PAAs, a close topographical relationship between Islet-1-expressing cells and PAAs was maintained. These results suggest that Islet-1-expressing cells may play a role in the longitudinal growth of PAAs in the dorsal funiculus.  相似文献   
13.
Capacitive heating is widely used in hyperthermic treatment of human malignancies. However, the pain on the body surface or thermoesthesia in the subcutaneous fatty layer may prevent an elevation of temperature in the tumors. Impedance matching is improved by a subtrap method entailing the application of two copper plates (10×850×0.06 mm) as a subtrap circuit to each of two capacitive electrodes. In a clinical trial the Tmax, Tave, Tmin for the subtrap method were all higher in comparison with those for the conventional technique (42.5±0.7°C, 41.9±1.0°C, 41.3±1.1°C vs. 41.1±1.5°C, 40.6±1.3°C, 40.0±1.3°C). Although the maximal radiofrequency (RF) power applied to patients was higher with the subtrap method (875±189 W vs. 763±200 W), the incidence of surface pain was reduced dramatically. It is concluded that the subtrap method substantially improves the RF capacitive heating of deep-seated tumors.  相似文献   
14.
To examine the role of c-Jun N-terminal kinase (JNK/SAPK) in the developing nervous system of vertebrates, the localization of an active form of JNK, phosphorylated JNK (p-JNK), was studied in the lumbosacral spinal cord of the chick embryo. We also examined the localization of phosphorylated neurofilaments (NFs, potential targets of p-JNK) and cyclin-dependent kinase 5 (Cdk5), which is known to phosphorylate cytoskeletal proteins, including NFs, and compared their expression with that of p-JNK. Additionally, the localization of phosphorylated forms of c-Jun and ATF-2 was compared with that of p-JNK. On embryonic day 3 (E3), the expression of p-JNK was observed in regions containing early-projecting axons. Axons in these regions also expressed phosphorylated NFs. Subsequently, on E5 and E8, the expression of both p-JNK and phosphorylated NFs increased concomitantly in the axonal tracts in the spinal white matter. Thus, white matter expressed both p-JNK and phosphorylated NFs, whereas there was only weak expression of Cdk5. By E13, the spinal cord expression pattern of p-JNK and phosphorylated NFs had changed compared to earlier ages. Although phosphorylated NFs were still expressed in the white matter, the expression of p-JNK was decreased in axons in the white matter, whereas strong p-JNK expression appeared in cell nuclei in the gray matter. In summary, the present study revealed that the localization of p-JNK in the spinal cord changes dramatically from axons to cell nuclei during development, suggesting multiple roles of p-JNK, depending on the developmental age.  相似文献   
15.
The longitudinal elongation of primary afferent axons (PAAs) in the dorsal funiculus of chick embryo spinal cord was examined using a lipophilic tracer, DiI and immunohistochemistry. The earliest developing PAAs in the brachial segments invaded the spinal cord around embryonic day (E) 3.5. Thereafter, they elongated both rostrally and caudally in the presumptive dorsal funiculus, with frequent contacts between pre-existing axons and later arriving growth cones. By E4, the PAAs had elongated 3 segments both rostrally and caudally. In the course of their longitudinal elongation, the PAAs shifted their trajectory dorsally within the dorsal funiculus. By E6-6.5, the PAAs had extended as far as 10 segments rostrally and 6 segments caudally in the dorsal funiculus, and collaterals began to enter the dorsal horn. By E9, the PAAs extended up to 13 segments rostrally and 7 segments caudally, and collaterals reached the ventral spinal cord. During their longitudinal course, the PAAs shifted their trajectory medially within the dorsal funiculus.  相似文献   
16.
Interventional cardiology (n = 108) and cardiac angiography (n = 481) procedures in pediatrics performed between January 1996 and December 1998 were reviewed. Means (SD) of duration of anesthesia for interventional cardiology and cardiac angiography were 245 (130) and 152 (48) minutes, respectively (P < 0.001). Incidences of long operations requiring over 6 hours of anesthesia were 12 and 0%, respectively (P < 0.001). Incidences of hemodynamic derangements were 17 and 2.9%, and catheter-related complications were 7.4 and 0.83%, respectively (P < 0.001). Incidences of ICU admission were 7.4 and 0.62% those of emergency surgery were 4.6 and 0%, and those of blood transfusion were 4.6 and 0%, respectively (P < 0.001). Incidences of cardiopulmonary resuscitation, and cardioversion were also higher in interventional cardiology (P < 0.05), and all these emergency cases were rescued successfully. The risk of cardiac angiography is higher compared with general surgery, and the risk of interventional cardiology is higher than cardiac angiography in pediatrics. This study reconfirms that anesthesiologists should play an active role in care of pediatric patients undergoing high-risk procedures outside the operating room.  相似文献   
17.
BACKGROUND: In clinical studies, it has been difficult to evaluate the influence of haemodialysis (HD) parameters on HD clearance (CL(HD)) and reduction rate (RR) of non-ionic contrast medium during HD sessions. We therefore predicted clinical values of CL(HD) and RR of iopromide, a non-ionic contrast medium, from findings obtained from in vitro experiments, and confirmed that these predictive values were comparable with the actual values in clinical cases. METHODS: We developed a correlation equation for predicting CL(HD) on the basis of in vitro HD experiments by varying blood flow rates between 100 and 200 ml/min with a cuprammonium rayon dialyser (AM-SD-10H). Total body clearance of iopromide (CL(PT)) was estimated by the Cockroft-Gault equation. The volume of distribution (V(d)) was obtained from the reported value. By using the HD and three pharmacokinetic parameters (CL(HD), CL(PT) and V(d)), we predicted CL(HD) and RR for seven patients undergoing HD after the administration of iopromide. RESULTS: In the in vitro study, the mean values (+/-SD) of iopromide clearance at blood flow rates of 100, 150 and 200 ml/min were 45.35 (2.54), 53.88 (6.46) and 57.61 (4.72) ml/min, respectively. There were highly significant correlations between clearance and blood flow rate (r = 0.975). Although the predicted CL(HD) showed a tendency towards underestimation, a good correlation was found. Predicted RR values were similar to observed values except for one case. CONCLUSION: The in vitro model used in the present study provides pertinent information about CL(HD) and is helpful for predicting RR during HD in individual patients undergoing HD.  相似文献   
18.
We herein report a case of bilateral testicular germ cell tumor recurring 31 years after right high inguinal orchiectomy. In 2003, a 62-year-old man presented with a mass in the left testis. Ultrasonography demonstrated three hypoechoic mass and microlithiasis of the left testis. Abdominal and breast computed tomography revealed no lymph adenopathy and any metastasis. The preoperative diagnosis was stage I testicular tumor and subsequently left high orchiectomy was performed. Histological examination revealed typical seminoma. At present, the patient is free from recurrence after the surgery. To our knowledge, 166 cases were reported in Japan. Approximately fifty percent of metachronal bilateral testicular tumors previously reported have been recurred after five years and more from the initial surgery. In the testicular cancer, long-term follow-up and self examination of the scrotum are of great importance. We review the metachronal bilateral testicular germ cell tumors previously reported in Japan.  相似文献   
19.

Purpose

Hypoxia, a prognostic factor in many types of cancer, can be detected by 18F-fluoromisonidazole (FMISO) positron emission tomography (PET). It is unclear whether hypoxia reflects the response to chemotherapy in patients with oral squamous cell carcinoma (OSCC). The correlations of FMISO-PET and FDG-PET with histological response to preoperative chemotherapy were therefore assessed in patients with OSCC.

Methods

This study enrolled 22 patients with OSCC undergoing preoperative chemotherapy. The T-stages were T2 in 6 patients, T3 in 3, and T4a in 13, and the N-stages were N0 in 14 patients, N1 in 3, and N2 in 5. Each patient was evaluated by both FMISO-PET and FDG-PET before surgery, and the maximum standardized uptake value (SUVmax) of FDG- and FMISO-PET and tumor-muscle ratio (TMR) of FMISO-PET were measured. The threshold for the hypoxic volume based on TMR was set at 1.25. The histological response to preoperative chemotherapy was evaluated using operative materials.

Results

FMISO-PET and FDG-PET detected uptake by primary OSCCs in 15 (68 %) and 21 (95 %) patients, respectively, and median SUVmaxs of FMISO- and FDG-PET in the primary site were 2.0 (range, 1.3–3.5) and 16.0 (range, 1.0–32.2), respectively. The median of FMISO TMR was 1.5 (range, 0.99–2.96). There were five cases whose FMISO TMR was less than 1.25. Histological evaluation showed good response to preoperative chemotherapy in 7 patients (32 %) and poor response in 15 (68 %). Good response was significantly more prevalent in patients with negative than positive FMISO uptake (P?P?=?0.04), whereas FDG uptake was not significantly correlated with response to chemotherapy response. Multivariate logistic regression analysis showed that FMISO uptake was an independent significant predictor of response to preoperative chemotherapy (P?=?0.03, odds ratio?=?0.06, 95 % confidence interval?=?0.004–0.759).

Conclusions

An advantage of FMISO-PET over FDG-PET for predicting histological response to preoperative chemotherapy in patients with OSCC was observed.  相似文献   
20.
OBJECTIVE: We sought to assess the efficacy of combined therapy after superselective arterial cisplatin infusion (SACI) therapy to treat the maxillary squamous cell carcinoma. STUDY DESIGN: We conducted a retrospective chart review of 50 patients. After completion of two courses of SACI, 25 of the patients were successively treated by concurrent SACI and radiotherapy (AR), while the other 25 patients were treated by surgery with postoperative radiotherapy (ASR). RESULTS: Patients with surgery (ASR) had an 88% local control rate with 75% disease-free survival rate at 60 months by Kaplan-Meier analysis, compared with 62% disease-free survival rate for patients with AR treatment. A particularly good outcome was obtained in T4 cases of the ASR group (n=8) whose 5-year survival rate was 87% and local control rate was 100%. CONCLUSION/SIGNIFICANCE: Combined SACI therapy is very effective for the treatment of maxillary squamous cell carcinomas and contributes to the improving prognoses of patients and organ preservation rates.  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