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   8670篇
  免费   407篇
  国内免费   59篇
耳鼻咽喉   54篇
儿科学   144篇
妇产科学   76篇
基础医学   1228篇
口腔科学   160篇
临床医学   650篇
内科学   2400篇
皮肤病学   33篇
神经病学   1007篇
特种医学   254篇
外科学   1208篇
综合类   38篇
预防医学   196篇
眼科学   126篇
药学   733篇
中国医学   22篇
肿瘤学   807篇
  2023年   31篇
  2022年   67篇
  2021年   178篇
  2020年   86篇
  2019年   106篇
  2018年   145篇
  2017年   110篇
  2016年   144篇
  2015年   168篇
  2014年   203篇
  2013年   298篇
  2012年   445篇
  2011年   562篇
  2010年   326篇
  2009年   273篇
  2008年   477篇
  2007年   509篇
  2006年   512篇
  2005年   465篇
  2004年   473篇
  2003年   502篇
  2002年   489篇
  2001年   183篇
  2000年   139篇
  1999年   179篇
  1998年   126篇
  1997年   112篇
  1996年   109篇
  1995年   84篇
  1994年   104篇
  1993年   87篇
  1992年   130篇
  1991年   126篇
  1990年   125篇
  1989年   117篇
  1988年   110篇
  1987年   90篇
  1986年   101篇
  1985年   93篇
  1984年   66篇
  1983年   51篇
  1982年   37篇
  1981年   32篇
  1980年   32篇
  1979年   28篇
  1978年   27篇
  1977年   29篇
  1971年   24篇
  1970年   28篇
  1968年   23篇
排序方式: 共有9136条查询结果,搜索用时 31 毫秒
991.
992.
Neurological symptoms induced by the infiltration of malignant lymphoma into the nervous systems are subsumed under the term neurolymphomatosis (NL). Here, we report the case of a 30-year-old Japanese man with primary testicular lymphoma complicated, as seen in various neurological findings, by secondary NL prior to testicular swelling. Painless right scrotal enlargement was noticed more than 1 month after the appearance of neurological complications such as right upper extremity numbness, dysarthria, facial palsy, and diplopia. Proactive investigation and biopsies of extranodal sites at high risk of central nervous system infiltration of malignant lymphoma, such as the testes, should be considered when secondary NL is suspected based on imaging findings.Key Words: Neurolymphomatosis, Primary testicular lymphoma, Diffuse large B-cell lymphoma, Central nervous system infiltration  相似文献   
993.
NANOG expression in prostate cancer is highly correlated with cancer stem cell characteristics and resistance to androgen deprivation. However, it is not clear whether NANOG or its pseudogenes contribute to the malignant potential of cancer. We established NANOG- and NANOGP8-knockout DU145 prostate cancer cell lines using the CRISPR/Cas9 system. Knockouts of NANOG and NANOGP8 significantly attenuated malignant potential, including sphere formation, anchorage-independent growth, migration capability, and drug resistance, compared to parental DU145 cells. NANOG and NANOGP8 knockout did not inhibit in vitro cell proliferation, but in vivo tumorigenic potential decreased significantly. These phenotypes were recovered in NANOG- and NANOGP8-rescued cell lines. These results indicate that NANOG and NANOGP8 proteins are expressed in prostate cancer cell lines, and NANOG and NANOGP8 equally contribute to the high malignant potential of prostate cancer.  相似文献   
994.

Purpose

In pediatric dentistry, sealants have been used to prevent caries. Due to its material properties such as fluoride-releasing ability and physical strength, surface pre-reacted glass (S-PRG) filler is added primarily to resin-based dental materials for clinical use. In this study, we investigated the properties of S-PRG filler containing sealant.

Methods

Before using sealant, the primer was applied to extracted bovine incisors. Scanning electron microscopy (SEM) observation revealed that the primer treatment caused no structural changes of enamel surface, unlike conventional phosphoric acid etching. Further, shear bond strength test was performed to measure the initial strength and durability after thermal cycling. Bond strength of S-PRG filler containing sealant was comparable to those of other sealants even though the former does not involve phosphoric acid etching. In addition, after treating the enamel surface with the primer or phosphoric acid, it showed excellent flowability in the primer group compared to phosphoric acid treatment.

Results

SEM observation showed that the sealant sealed the enamel surface as it migrated to reach the deep areas of the fissures. When the marginal sealing ability of the sealant was evaluated based on dye penetration, no dye penetration in the marginal region was observed in any specimens. In addition, measurement of the pH of an acid solution containing a cured specimen of the sealant containing S-PRG filler showed that the solution's pH became more alkaline as the immersion time increased.

Conclusion

These findings suggest that the sealant is an extremely effective material for preventing caries.  相似文献   
995.

Purpose  

To investigate the treatment and outcomes in a series of seven cases of small bowel metastases from lung cancer.  相似文献   
996.
997.
998.

Background

This study was conducted to standardize treatment and determine patient and renal outcome in Japanese anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis/rapidly progressive glomerulonephritis (AAV/RPGN) patients, because the prognosis of AAV/RPGN patients in Japan had been poor compared with that of other countries.

Methods

The participants in this retrospective cohort study were 824 ANCA-positive RPGN patients, 705 of whom were only myeloperoxidase (MPO)-ANCA positive.

Results

Among the early-years cohort (group?A; cases diagnosed between 1988 and 1998), patients frequently died due to opportunistic infection. Therefore, we recommended a reduced dose of prednisolone (oral prednisolone dose <0.8?mg/kg/day) with or without cyclophosphamide for initial treatment of Japanese RPGN patients. After this recommendation, 1-year survival of the patients improved: 75% in group?A, 79% in group?B (between 1999 and 2002), and 81% in group?C (after 2003). During the entire observation period, average serum creatinine level at the start of treatment decreased, and improvement of 1-year renal survival was also found (72% in group?A, 83% in group?B, and 83% in group?C), while the recurrence rate was significantly increased in group?C (0.05/patient-year in group?A, 0.07/patient-year in group?B, and 0.13/patient-year in group?C).

Conclusions

Oral prednisolone dose <0.8?mg/kg/day with or without cyclophosphamide as an initial treatment could improve patient survival in older Japanese AAV/RPGN patients. However, maintenance treatment avoiding relapse should be established to improve renal outcomes.  相似文献   
999.

Background

The tissue-protective effects of erythropoietin (EPO) have been extensively investigated, and EPO administration can raise the hemoglobin (Hb) concentration. Recently, we reported that carbamylated erythropoietin (CEPO) protected kidneys from ischemia-reperfusion injury as well as EPO.

Methods

To investigate the clinical applications of CEPO, we next evaluated the long-term therapeutic effect of CEPO using a tubulointerstitial model rat. We randomized remnant kidney model rats to receive saline, EPO, or CEPO for 8?weeks.

Results

CEPO- and EPO-treated rats had improved serum creatinine levels compared with saline-treated remnant kidney model rats, although the Hb level was significantly increased in EPO-treated rats. Two-photon microscopy revealed that EPO/CEPO significantly ameliorated tubular epithelial cell damage assessed by endocytosis. In addition, CEPO or EPO protected endothelial cells with a sustained blood flow rate. EPO or CEPO suppressed the number of TUNEL-positive apoptotic cells with weak ??SMA staining. Furthermore, PCR analysis demonstrated that TGF-?? and type I collagen expression was attenuated in EPO- or CEPO-treated rats, accompanied by a significant decrease in interstitial fibrosis.

Conclusion

We established a long-term therapeutic approach to protect tubulointerstitial injury with CEPO, and thus, the therapeutic value of this approach warrants further attention and preclinical studies.  相似文献   
1000.
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