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   179721篇
  免费   1158篇
  国内免费   22篇
耳鼻咽喉   1174篇
儿科学   6910篇
妇产科学   3220篇
基础医学   17010篇
口腔科学   1671篇
临床医学   12534篇
内科学   31630篇
皮肤病学   890篇
神经病学   16614篇
特种医学   9050篇
外科学   29547篇
综合类   2500篇
一般理论   2篇
预防医学   18284篇
眼科学   2858篇
药学   9685篇
中国医学   642篇
肿瘤学   16680篇
  2023年   44篇
  2022年   102篇
  2021年   185篇
  2020年   102篇
  2019年   120篇
  2018年   22030篇
  2017年   17450篇
  2016年   19623篇
  2015年   1025篇
  2014年   987篇
  2013年   982篇
  2012年   7258篇
  2011年   21297篇
  2010年   18965篇
  2009年   11638篇
  2008年   19711篇
  2007年   21887篇
  2006年   733篇
  2005年   2308篇
  2004年   3501篇
  2003年   4417篇
  2002年   2576篇
  2001年   378篇
  2000年   508篇
  1999年   253篇
  1998年   246篇
  1997年   236篇
  1996年   131篇
  1995年   136篇
  1994年   122篇
  1993年   77篇
  1992年   93篇
  1991年   139篇
  1990年   196篇
  1989年   129篇
  1988年   125篇
  1987年   91篇
  1986年   66篇
  1985年   69篇
  1984年   50篇
  1983年   53篇
  1982年   40篇
  1980年   54篇
  1976年   32篇
  1974年   32篇
  1970年   35篇
  1968年   32篇
  1938年   62篇
  1932年   57篇
  1930年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Objectives The aim of this prospective study is to evaluate patients with erectile dysfunction (ED) in terms of coronary artery calcium (CAC) levels assessed by multidetector computed tomography (MDCT) and to find out if ED severity may predict coronary heart disease risk. Patients and method Sixty men with a mean age of 55.7 (41–77) years with ED and 23 men with a mean age of 53.2 (39–76) years without ED, who admitted to our clinic between January 2005 and December 2005, were included in the study. All patients answered the standard International Index of Erectile Function (IIEF) forms, and were classified into four groups as mild, moderate, severe ED and no ED. CAC levels were assessed by MDCT protocol. CAC levels and IIEF scores were analyzed within each group. Results Pearson correlation test demonstrated significant negative correlation between IIEF score and CAC score (r = −497; P < 0.0001). CAC scores increased significantly with regard to IIEF scores decrease: IIEF 1–10 (n = 18), mean CAC: 557.7; IIEF 11–16 (n = 13), mean CAC: 541.3; IIEF 17–25 (n = 29), mean CAC: 84.6; and IIEF ≥ 26 [n = 23 (Control group)], mean CAC: 10.1. The difference between the mean CAC scores of these four groups was statistically significant (P < 0.0001). When we took the cut-off value for IIEF score 26 we observed significantly higher CAC scores at the group of IIEF < 26 (mean 325.5 vs 10.1; P < 0.0001). Conclusion We observed positive correlation with ED severity and CAC levels. Therefore, we think that detection and quantification of preclinical coronary artery disease by CAC scoring with a non-invasive method might have a great potential for early cardiac preventive measures.  相似文献   
992.
The feasibility and diagnostic reliability of sentinel node (SN) biopsy for gastric cancer are still controversial. We studied the clinicopathological features and localization of solitary lymph node metastasis (SLM) in gastric cancer to provide useful information for use of the SN concept in gastric cancer. From 2000 to 2004, 3,267 patients with gastric cancer underwent D2 radical gastrectomy. The clinicopathological features of 195 patients with histologically proven SLM and the distribution of metastasized nodes were assessed. The incidence of SLM was 6.0% in all cases. Compared with the node-negative patients, significant differences were observed in age, tumor size, depth of invasion, and surgical type. The cumulative 5-year survival rate of patients with SLM was 80.5%, which was significantly lower than 90.2% for node-negative patients (P < 0.001). Of patients with SLM, 82.6% had it in the perigastric node area (N1), and the other 17.4% patients had skip metastasis in the N2-N3 nodes. Perigastric nodes were the most common first sites of drainage from the tumor, making them the main targets of the operative SN mapping procedure. Due to the higher than expected incidence of skip metastasis in gastric cancer, D2 lymphadenectomy should be performed until the reliability of SN navigation surgery is validated in multicenter prospective clinical trials.  相似文献   
993.
Appendectomy is the most common non-gynecologic surgery performed during pregnancy. Little data exist on the accuracy of imaging studies in the diagnosis of appendicitis in pregnancy. The objective of this study was to evaluate the probability of ultrasound and computed tomography (CT) scan in diagnosing appendicitis in pregnancy, as reflected in the negative appendectomy rate. We retrospectively reviewed the charts of 86 pregnant women who underwent an appendectomy between January 1, 1997 and January 1, 2006. Patients were divided into three groups: clinical evaluation, ultrasound, and ultrasound followed by a CT scan. The clinical evaluation group had 13 patients, with a negative appendectomy rate of 54% (7/13). Fifty-five patients underwent an ultrasound alone, with a negative appendectomy rate 36% (20/55). In the ultrasound/CT group (n = 13), the negative appendectomy rate was 8% (1/13). There was a significant reduction in the negative appendectomy rate in the ultrasound/CT scan group compared to clinical evaluation group (54 vs 8%, p < 0.05). This reduction was not achieved in the ultrasound group when compared to the clinical evaluation group or the ultrasound/CT group (p = 0.05). A significant reduction was achieved when the ultrasound/CT group was compared to the patients in the ultrasound only group who had a normal or inconclusive ultrasound (p < 0.05). Our data documents a very high negative appendectomy rate in the pregnant patient. We recommend an ultrasound followed by a CT scan in patients with a normal or inconclusive ultrasound.  相似文献   
994.
In women, birth trauma can result in altered anatomy of supporting structures of the pelvic floor and in the development of urinary incontinence. The goal of this study was to investigate the association between parturition and the morphology and function of perineal and pelvic muscles in the female rabbit. In ten nulliparous and ten multiparous same-age females, we investigated morphological, histological (n = 5 females/group), and contractile characteristics (n = 5 females/group) of the perineal bulbospongiosus (Bsm) and the pelvic pubococcygeus (Pcm) muscles. Bsm and Pcm muscles of multiparous females were significantly lighter, they had a smaller cross-sectional fiber area, and developed significantly lower twitch and tetanic tension force in response to electrical stimulation than muscles of nulliparous females. In female rabbits, multiparity is associated with potentially pathological changes in the morphological and functional characteristics of these perineal and pelvic muscles, possibly as a result of stretching during parturition.  相似文献   
995.
Poor clinical results following total knee arthroplasty like flexion gap instability or anterior knee pain may be related to femoral component rotational malalignment. The transepicondylar axis has been recommended as a landmark to consistently recreate a balanced flexion gap. However, the reproducibility to identify the transepicondylar axis intraoperatively is low. In this feasibility study we wanted to find out whether fluoroscopy-based CT scans obtained by a motorized mobile C-arm (Iso C 3D) may be useful to asses the transepicondylar axis intraoperatively. Following the femoral resections the Iso C 3D was used intraoperatively in ten knees with mild to severe deformities. On multiplanar reconstructions of the distal femur the clinical epicondylar axis as well as the angle to the posterior cut (condylar twist angle) could be easily measured. The scanning time was 40 s and the extra time needed for the whole setup about five to ten minutes. The Iso C 3D was helpful to intraoperatively identify the transepicondylar axis and the condylar twist angle, especially in cases with severe deformity or dysplasia when standard landmarks are difficult to determine. Florian Geiger and Dominik Parsch contributed equally to this article.  相似文献   
996.
Tracheal chondrosarcomas are rare, with only 14 cases previously documented. We report a case of chondrosarcoma of the trachea and review other published cases. Our patient was a 34-year-old man who began to feel shortness of breath 8 months after initial hemoptysis. Transverse and coronal computed tomography demonstrated a tumor that was obstructing nearly 80% of the tracheal lumen at the thoracic inlet. A bronchoscopic biopsy specimen led to an initial diagnosis of chondroma. Five tracheal rings from the third to the seventh including the tumor were completely resected, and an end-to-end anastomosis was performed. The histological diagnosis of the surgical specimen showed it to be a chondrosarcoma. The patient was alive without recurrence at 6 years 4 months after surgery. Because recurrence after incomplete resection and malignant transformation can occur with chondromas, radical resection of the trachea is recommended for all cartilaginous tumors of the trachea.  相似文献   
997.
Background In 1998, the one-year experience in minimally invasive abdominal surgery in children at a pediatric training center was assessed. Seven years later, we determined the current status of pediatric minimally invasive surgery in daily practice and surgical training. Methods A retrospective review was undertaken of all children with intra-abdominal operations performed between 1 January 2005 and 31 December 2005. Results The type of operations performed ranged from common interventions to demanding laparoscopic procedures. 81% of all abdominal procedures were performed laparoscopically, with a complication rate stable at 6.9%, and conversion rate decreasing from 10% to 7.4%, compared to 1998. There were six new advanced laparoscopic procedures performed in 2005 as compared to 1998. The children in the open operated group were significantly smaller and younger than in the laparoscopic group (p < 0.001 and p = 0.001, respectively). The majority (64.2%) of the laparoscopic procedures were performed by a trainee. There was no difference in the operating times of open versus laparoscopic surgery, or of procedures performed by trainees versus staff surgeons. Laparoscopy by trainees did not have a negative impact on complication or conversion rates. Conclusions Laparoscopy is an established approach in abdominal procedures in children, and does not hamper surgical training.  相似文献   
998.
Objective To investigate whether stone dimension is a restrictive factor for ureterorenoscopic procedures. Materials and methods A group of 416 patients who had undergone ureterorenoscopic pneumatic lithotripsy (URS-PL) for lower ureteral stones between January 1999 and June 2006 in our clinic had been evaluated retrospectively. Two hundred and seventy (270, 64.9%) patients were men and 146 (35.1%) were women. The mean age of the patients was 36.61 (±12.43) years. Patients were grouped according to stone dimension; 193 patients with stones smaller than 1 cm being group 1 and 223 patients with stones ≥1 cm in dimension being group 2. Stone-free rate, operative time and rate of complications of the groups were compared. Pearson’s correlation test, χ2 test, Fischer’s exact test and Student’s t-test were used for the statistical analysis. The p value was accepted as being meaningful if p < 0.05. Results For group 1, the mean operative time was 39.19 (±18.33) min. Proximal stone migration in five and false passage formation in three patients was observed. Three patients were stone-free after a second session of URS-PL. The cumulative stone-free rate was 97.4% (188/193). For group 2, the mean operative time was 48.5 (±11.31) min. About 208 (93.27%) patients were stone-free after the first session and an additional eight patients became stone-free after the second session of URS-PL. False passage, ureteral perforation, ureteral avulsion and stricture were observed in four, six, one and one patients, respectively. No proximal stone migration was observed. The cumulative stone-free rate was 96.86% (216/223). Conclusions The effectiveness of ureterorenoscopy (URS) in the treatment of distal ureteral stones was independent of stone dimension. However, the operative time was longer and the rate of perforation was higher in stones with a diameter ≥1 cm. On the other hand, the migration rate was higher in stones <1 cm in diameter. Generally speaking, there was no meaningful effect of stone dimension on complication rates.  相似文献   
999.
1000.
Background Recently, it has been demonstrated that surgical treatment of hemorrhoids in a day-care basis is possible and safe. The aim of this study was to compare the Longo stapled hemorrhoidopexy (SH) and the Milligan–Morgan hemorrhoidectomy (MMH). Methods One hundred seventy one patients (95 cases in SH group and 76 cases in MMH group) entered the study: 83 cases were III degree hemorrhoids, 88 IV degree. A priori and a post hoc power analysis were performed. Results, prospectively collected, were compared using chi squared test and student t test. Visual analog scale was used for pain evaluation. Postoperative pain, duration of pain, wound secretion, bleeding, resumption of a normal lifestyle, and postoperative complication were evaluated. Results Surgical time was 28.41 ± 10.78 for MMH and 28.30 ± 13.28 min in SH (P = 0.94). Postoperative pain was not different between MMH and SH during the first two postoperative days (4.73 ± 2.91 vs 5.1 ± 3.048; P = 0.4), during the following 6 days, patients treated with SH had less pain (4.63 ± 2.04 in MMH vs 3.60 ± 2.35 in SH; P = 0.006). In the SH group, seven patients needed further hospital stay for complicated course. SH showed higher incidence of anal fissure compared with MMH (6.3% vs 0%; P = 0.025) but no differences in urinary retention, anal stricture, urgency, or anal hemorrhage. Conclusions This study confirms that SH is associated with less postoperative pain and shorter postoperative symptoms, compared with MMH. SH may be a viable addition to the therapy for hemorrhoids with some advantages in early postoperative pain and some disadvantages in postoperative complications and costs.  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