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   182462篇
  免费   1204篇
  国内免费   30篇
耳鼻咽喉   1176篇
儿科学   6729篇
妇产科学   3087篇
基础医学   17347篇
口腔科学   1711篇
临床医学   12819篇
内科学   32375篇
皮肤病学   869篇
神经病学   16941篇
特种医学   9168篇
外科学   29937篇
综合类   2337篇
预防医学   18291篇
眼科学   2768篇
药学   10400篇
中国医学   640篇
肿瘤学   17101篇
  2022年   45篇
  2021年   72篇
  2020年   44篇
  2019年   72篇
  2018年   21995篇
  2017年   17409篇
  2016年   19573篇
  2015年   965篇
  2014年   902篇
  2013年   887篇
  2012年   7169篇
  2011年   21282篇
  2010年   18949篇
  2009年   11638篇
  2008年   19766篇
  2007年   21993篇
  2006年   854篇
  2005年   2546篇
  2004年   3704篇
  2003年   4671篇
  2002年   2851篇
  2001年   614篇
  2000年   778篇
  1999年   484篇
  1998年   297篇
  1997年   285篇
  1996年   171篇
  1995年   173篇
  1994年   167篇
  1993年   128篇
  1992年   282篇
  1991年   321篇
  1990年   358篇
  1989年   291篇
  1988年   264篇
  1987年   222篇
  1986年   197篇
  1985年   209篇
  1984年   120篇
  1983年   105篇
  1982年   70篇
  1981年   32篇
  1980年   72篇
  1979年   72篇
  1978年   45篇
  1969年   30篇
  1938年   60篇
  1934年   31篇
  1932年   57篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
991.
In this study, we performed a mechanical analysis of the effect of fibroblast growth factor-2 (FGF-2) on autologous osteochondral transplantation in a rabbit model. A full-thickness cartilage defect (diameter: 5 mm; depth: 5 mm) made in the right femoral condyle was treated with osteochondral transplantation using an osteochondral plug (diameter: 6 mm; depth: 5 mm) taken from the left femoral condyle. The animals were divided into three groups: Group I, the defect was filled with 0.1 ml of gelatin hydrogel containing 1 microg of FGF-2; Group II, the defect was filled with 0.1 ml of gelatin hydrogel only; Group III, the defect was left untreated. Thereafter, osteochondral plugs were transplanted and the transplanted osteochondral grafts were evaluated mechanically and histologically at postoperative weeks 1, 3, 8 and 12. The structural property of the osteochondral graft was significantly greater in Group I than in Groups II and III at postoperative week 3. Histological analysis at 3 weeks revealed a tendency towards increased subchondral bone trabeculae in Group I compared with the other groups. Autologous osteochondral grafts transplanted with gelatin hydrogel containing FGF-2 acquired adequate stiffness at an early postoperative phase.  相似文献   
992.
Background and aims  Bleeding from the hepatic vein is closely related to central venous pressure (CVP). To evaluate the effect of low central venous pressure during a hepatectomy, the infrahepatic inferior vena cava (IVC) was half clamped. Patients and methods  Between 2006 and 2007, 20 patients undergoing major hepatectomy with the IVC half clamping (half-clamping group) were compared with 58 patients undergoing hepatectomy without IVC half clamping between 2003 and 2005 (control group). The types of liver resection, amount of blood loss during the hepatectomy, volume of blood transfusion, length of hospital stay, and complications were compared between the two groups. Results  In the half-clamping group, blood loss was decreased in comparison to the control group (p = 0.041) and the suprahepatic CVP was low (2.4 ± 1.8 mmHg; p = 0.0002). The diameter at the root of the right hepatic vein was reduced in comparison to before clamping (5.8 ± 1.6 mm; p < 0.001). There were no complications of half clamping on any hemodynamic and blood electrolytic parameters. Conclusion  Using the half clamping technique of the IVC, intra-operative CVP was maintained below 3 mmHg without any side effects, and the low CVP significantly reduced the bleeding from hepatic veins during a major hepatectomy.  相似文献   
993.
Purpose  The exact relationship between larger caseload volume and lower morbidity following esophagectomy has not been established. This study investigates the effect of surgical volumes on reducing postoperative complications and length of stay after esophagectomy. Methods  Patient and hospital data were collected electronically via a web-based questionnaire sent to surgeons in the Japan Surgical Society. Data were based on 642 patients treated with esophagectomy at 183 hospitals between November 1, 2006 and February 28, 2007. Multivariate analysis revealed that postoperative morbidity and length of stay regressed against hospital and surgeon volumes, patient characteristics, and details of the procedures. Results  In a logistic regression model, esophagectomies by surgeons performing a high volume of operations (>100 cases; “high case-volume surgeons”) were followed by a significantly lower rate of postoperative complications (odds ratio [OR], 0.49; 95% confidence interval (CI), 0.24–0.98, P = 0.04). In a proportional hazard model, high-volume surgeons reduced the length of stay significantly: the hazard ratio for medium casevolume surgeons (50–99 cases) was 1.53 [95% CI, 1.14–2.06, P = 0.00], whereas that for the highest case-volume surgeons was 1.34 [95% CI, 1.00–1.79, P = 0.05] vs the lowest case-volume surgeons. Neither postoperative complications nor length of stay were significantly associated with hospital volume. Conclusion  These findings indicate that morbidity after esophagectomy is more dependent on individual surgeon-specific skill than on hospital-based factors.  相似文献   
994.
This biographical sketch of Marshall R. Urist corresponds to the historic texts, The Classic: Bone Morphogenetic Protein, available at DOI  10.1007/s11999-009-1068-3; The Classic: A Morphogenetic Matrix for Differentiation of Cartilage in Tissue Culture, available at DOI  10.1007/s11999-009-1069-2; and The Classic: A Morphogenetic Matrix for Differentiation of Bone Tissue, available at DOI  10.1007/s11999-009-1070-9.  相似文献   
995.
We assessed the impact of bother with urinary and bowel dysfunction on social activities among men in Japan and the United States following primary therapy for localized prostate cancer. In paired longitudinal outcomes studies, we measured general and disease-specific health-related quality of life in 400 Japanese and 427 American men who underwent radical prostatectomy or brachytherapy for localized prostate cancer. Outcomes included the social function domain of the Medical Outcomes Study Short Form-36 and the University of California, Los Angeles Prostate Cancer Index, all of which are scored 0-100. Participants completed the questionnaires before and 1, 12 and 24 months after treatment. Among men who reported any urinary bother, Japanese men had slightly better urinary function than American men (84 vs 77, P<0.01). Before brachytherapy, urinary bother was weakly correlated with social function in both the countries; after brachytherapy, urinary bother was strongly correlated with social function in American but not Japanese men. After brachytherapy, bowel dysfunction had a stronger correlation with social function in American than Japanese men (P<0.05). The bother associated with urinary and bowel dysfunction after surgery or brachytherapy for prostate cancer has a greater impact on social function in American men than in Japanese men.  相似文献   
996.

Objective

We evaluated the correlation of radiological findings obtained by MRI study with pathological diagnosis in invasive bladder cancer treated with neoadjuvant chemotherapy, with or without radiation.

Design, Setting, and Participants

Twenty-seven patients, who underwent total or partial cystectomy for invasive bladder tumors, were enrolled into the present study. Eight cases had received neoadjuvant chemotherapy following the staging biopsy (group A), ten cases had received chemo-radiation therapy following the staging biopsy (group B), and nine cases had received preoperative staging biopsy alone (group C). As a final treatment, 12 of the 27 patients underwent total cystectomy and the other 15 patients underwent partial cystectomy. MRI was conducted prior to total or partial cystectomy in each case. The pathological stage was assessed by histological examination of the entire layer of the bladder wall.

Results and Limitations

Tumor stage assessed by MRI was consistent with pathological findings in 16 of the 27 cases (59.3%), while MRI produced over-staging in 7 cases and under-staging in 4 cases. The accuracy of staging was 75.0, 30.0, and 77.8% in groups A, B, and C, respectively. The accuracy of MRI staging in group B was lower than that in group C (P < 0.05). There was no difference in the accuracy of MRI staging between groups A and C.

Conclusion

MRI is useful for the staging of bladder cancer. However, care needs to be taken when staging invasive bladder tumors treated with neoadjuvant chemo-radiation therapy, because inflammatory infiltrations and/or fibrous changes caused by the chemotherapy or chemo-radiation therapy make precise staging with MRI difficult.  相似文献   
997.
998.
Intrasellar meningioma: characteristic imaging findings   总被引:2,自引:0,他引:2  
Intrasellar meningioma is rare. We present a case in which both angiography and dynamic contrast-enhanced MRI suggests the diagnosis.  相似文献   
999.
1000.
Objective: It is controversial whether or not surgery is beneficial for patients with non-small cell lung cancer accompanied by persistent lymph node metastasis in the mediastinum following induction therapy. We have therefore conducted a retrospective study to assess this issue Methods: Eligibility criteria were defined as follows: 1) the period of treatment was between January 1991 and April 1998, 2) the clinical stages were IIIA (N2) or IIIB (N3) with large lymph nodes (> or = 2 cm), 3) induction therapy had been administered, 4) tumor was resected completely, 5) at least one mediastinal lymph node had necrosis or scar if the pathological N status was p-N0 or p-N1 and 6) the p-stage was not IV. Dichotomous variables included the radiographic response of the tumor, the T status, and the N status. Results: Thirty-nine patients were eligible. There were 29 males and 10 females aged from 27 to 74 years, and involved 20 cases of adenocarcinoma. The pathological N status was as follows: p-N0 in 18 patients, p-N1 in 3, p-N2 in 16, and p-N3 in the other 2. In overall survival, the median survival time (MST) was 34 months and the actuarial 5-year-survival rate (5-YSR) was 28%. The group of patients with either N0 or N1 (n-21) had a 71-month MST and a 54% 5-YSR, and the group of patients with either N2 or N3 (n=18) had a 13-month MST and a 5-YSR of 0% (p<0.0001). On multivariate analysis, the pathological N factor was confirmed as an independently significant. Conclusions: Our retrospective study found that the survival rate of patients with persistent mediastinal nodal metastasis was very poor. A prospective study is needed to investigate whether or not surgery is beneficial for these patients.  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