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   13369篇
  免费   668篇
  国内免费   118篇
耳鼻咽喉   356篇
儿科学   647篇
妇产科学   557篇
基础医学   977篇
口腔科学   457篇
临床医学   1088篇
内科学   3393篇
皮肤病学   220篇
神经病学   788篇
特种医学   568篇
外科学   3154篇
综合类   178篇
一般理论   1篇
预防医学   297篇
眼科学   480篇
药学   499篇
中国医学   26篇
肿瘤学   469篇
  2024年   12篇
  2023年   115篇
  2022年   220篇
  2021年   401篇
  2020年   255篇
  2019年   317篇
  2018年   408篇
  2017年   325篇
  2016年   557篇
  2015年   616篇
  2014年   688篇
  2013年   821篇
  2012年   1078篇
  2011年   962篇
  2010年   600篇
  2009年   513篇
  2008年   905篇
  2007年   1042篇
  2006年   955篇
  2005年   944篇
  2004年   823篇
  2003年   621篇
  2002年   545篇
  2001年   89篇
  2000年   48篇
  1999年   58篇
  1998年   58篇
  1997年   48篇
  1996年   31篇
  1995年   24篇
  1994年   17篇
  1993年   8篇
  1992年   10篇
  1991年   12篇
  1990年   10篇
  1989年   4篇
  1988年   2篇
  1986年   2篇
  1985年   4篇
  1984年   1篇
  1979年   2篇
  1978年   1篇
  1975年   1篇
  1973年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
This study aims to evaluate the effects of gamma-hydroxybutyrate (GHB) after spinal cord trauma (SCT). Twenty rabbits were divided equally into four groups: group I was the sham-operated group, group II suffered from SCT but received no treatment, group III was given a dose of 400 mg/kg of GHB intravenously before SCT and group IV received the same dose after SCT. Cerebrospinal fluid (CSF) samples were obtained 30 min before SCT (T(0)), at 60 (T(1)) and 120 min (T(2)) after SCT. There was a threefold increase in lactate levels from baseline value at T(2) in group II, while statistically significant elevation of the lactate levels were not observed in groups III and IV. Glucose levels at T(1) and T(2) were significantly lower in groups III and IV compared with the control group. The findings of this study demonstrate that GHB can control the increase of CSF lactate and glucose levels following SCT and that this metabolic effect may be associated with neuroprotective physiological changes.  相似文献   
22.
23.
Influence of a self-etching primer on compound nerve action potentials   总被引:1,自引:0,他引:1  
The aim of this study was to evaluate the effect of self-etching primers on nerve conductance. A self-etching primer (One Up Bond F) which combines etching and bonding in one step, and a fifth-generation bonding agent (Prime&Bond NT ) were tested. Isolated rat sciatic nerves were placed between two platinum electrodes in a bath containing Tyrode solution. The bonding agents were brought into contact with the nerves and the evoked compound action potentials (CAP) were recorded before and after contact with the materials. One Up Bond F caused total inhibition of the CAP within an average time of 7 min. All CAPs in this group were blocked irreversibly. As with Prime&Bond NT, the reduction in CAP was 45.9% after an application time of 15 min, after which readings were terminated. Recovery of the CAP in this group were maintained after rinsing with fresh tyrode solution. One Up Bond F elicited faster blocking of nerve conductance under the conditions of this model. In the context of dentin desensitization with bonding agents, the self-etching primer may be more effective, clinically.  相似文献   
24.
Antioxidant capacity and nitric oxide in patients with hepatic cirrhosis   总被引:2,自引:0,他引:2  
This study investigated the relationship between the antioxidant capacity of blood and the serum level of nitric oxide (NO) in patients with hepatic cirrhosis. The study included 20 patients with compensated cirrhosis (group I), 30 with decompensated cirrhosis (group II), and 30 healthy controls (group III). The serum levels of NO, albumin, bilirubin, and uric acid, and the erythrocyte activity of superoxide dismutase (SOD) were measured in all groups. The mean erythrocyte SOD activity (5.94 +/- 3.21 U/mg protein) and serum NO level (25.19 +/- 8.15 micromol/L) in group I were similar to those of controls (6.86 +/- 2.47 U/mg protein and 21.67 +/- 6.51 micromol/L, respectively). However, erythrocyte SOD activity in group II was significantly lower than in groups I and III and mean serum NO level was significantly higher in group II than in groups I and III. In regard to non-enzymatic antioxidants, the mean serum albumin level was lower and the mean serum total bilirubin level was higher in group II than in groups I and III. As expected, group I had higher mean serum total bilirubin level than the control group. Correlation analysis showed that erythrocyte SOD activity in cirrhotic patients was negatively correlated with their serum levels of NO. These results suggest that disturbances of antioxidative mechanisms may diminish hepatic resistance to oxidative stress, thereby contributing to the development of fibrogenesis.  相似文献   
25.
International Urology and Nephrology - To investigate the role of urinary neutrophil gelatinase-induced lipocalin (uNGAL) measurement in the early diagnosis of acute kidney injury that may occur...  相似文献   
26.
International Urology and Nephrology - To evaluate the effect of masturbation on the spontaneous expulsion of distal ureteral stones 5–10 mm in size. A total of 128 men with distal...  相似文献   
27.
Purpose

To evaluate the effect of artery-only (AO) and artery–vein (AV) clamping during partial nephrectomy (PN) on short- and long-term renal function outcome.

Methods

Medical records of 154 patients in the AO group and 192 patients in the AV group who underwent open and minimally invasive (laparoscopic/robotic) PN between January 2011 and January 2018 were retrospectively assessed. Preoperative patient and tumor-specific characteristics in addition to perioperative factors and renal function outcomes were compared. The change in the estimated glomerular filtration rate (eGFR) from postoperative 1–3 days, 12 and 24 months after surgery was calculated. Acute kidney injury (AKI) was defined a as a?>?25% reduction in eGFR.

Results

There were no statistically significant differences between the clamping techniques in terms of postoperative 1–3 days, 12 and 24 months eGFR change percentage and risk of progression to chronic kidney disease (CKD). No significant difference in short- and long-term renal functions was found between the minimally invasive or open AO and AV clamping subgroups at any time point. In multivariate analysis, the R.E.N.A.L score (AO group p?=?0.026, AV group p?<?0.001) and preoperative eGFR (AO group p?<?0.001, AV group p?=?0.010) were strong predictors of the acute kidney injury in both groups. Older age (AO group p?=?0.045, AV group p?=?0.010) and preoperative eGFR (AO group p?=?0.008, AV group p?=?0.002) were significantly associated with CKD progression at 2-year follow-up in both groups.

Conclusion

AV clamping does not adversely affect postoperative renal function compared to AO clamping. Preoperative patient- and tumor-related factors are more important for renal function regardless of the clamping technique.

  相似文献   
28.
We aimed to evaluate the learning curve of the surgically standardised ‘Omega Sign’ anatomical endoscopic enucleation (AEEP) of the prostate surgery technique for junior surgeons. This study is a retrospective comparison of cases that underwent AEEP by a mentor surgeon and three junior surgeons who have completed their learning curve. A video-based laser enucleation of the prostate assessment tool (LEAT) composed of 8 steps of the technique was used to assess a senior surgeon and junior surgeons’ surgical compatibility and consistency. The surgeon who defined Omega Sign technique was determined as group 1, and cases by three junior surgeons were identified as group 2. The end points were to assess the reproducibility and repeatability and operative post-operative outcomes of the technique. 55 patients’ videos were rated by five experienced endourologists. There was no significant difference in LEAT scores between the groups among all steps. The most symmetry was found in the 1st and 3rd steps. Inter-rater consistency was also high for each step, with no statistically significant difference between the evaluators. The standardised anatomical ‘Omega Sign’ technique is reproducible for the junior surgeons. The operative steps can be performed with high consistency, and the functional and perioperative outcomes are comparable with the senior surgeon.  相似文献   
29.
We aimed to evaluate the effect of shift work on semen parameters together with the effect of sleep quality in men attending infertility clinic. The participants were divided into two groups as follows: 104 shift worker men (Group 1) and 116 nonshift worker men (Group 2). Groups were compared in terms of semen parameters, Depression Anxiety Stress Scale-21 (DASS-21), and Pittsburg Sleep Quality Index (PSQI) scores. A higher rate of oligozoospermia and poor sleep quality and a lower mean normal morphology percentage was observed in shift workers than nonshift workers (p = .006, .039 and .036 respectively). In addition, a positive correlation was seen between sleep duration and sperm concentration, while a negative correlation was found between sleep latency and total sperm count. Shift working together with high PSQI score was also a significant association with oligozoospermia when controlling for the other variables of age, total testosterone, DASS-21 stress score, smoking and varicocele (OR = 2.11, 95% CI 1.03–4.34 and OR = 1.18, 95% CI 1.01–1.39 respectively). In this study, infertile shift workers had a lower percentage of normal morphology and higher rates of oligozoospermia and poor sleep quality. Considering that shift workers have lower sleep quality, it seems that shift working negatively affects the circadian rhythm.  相似文献   
30.
Right ventricular (RV) perforation is a rare but life‐threatening complication of pericardiocentesis and is usually treated surgically. We presented a case of RV free wall perforation, which occurred during pericardiocentesis and tried to be closed percutaneously with the Amplatzer vascular plug‐III (AVP‐III) device. The occluder device sealed the perforation, but it was in an insecure position; therefore, the patient underwent surgical repair. As an AVP‐III device, with a middle disk thicker than the RV myocardium, it may cause the RV myocardium to stretch outwards, so it should not be used for the treatment of RV perforation by the transcatheter way.  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