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   1444篇
  免费   89篇
  国内免费   21篇
耳鼻咽喉   2篇
儿科学   121篇
妇产科学   25篇
基础医学   188篇
口腔科学   36篇
临床医学   122篇
内科学   194篇
皮肤病学   18篇
神经病学   192篇
特种医学   122篇
外科学   208篇
综合类   55篇
预防医学   125篇
眼科学   24篇
药学   76篇
中国医学   1篇
肿瘤学   45篇
  2022年   8篇
  2021年   10篇
  2020年   9篇
  2019年   13篇
  2018年   22篇
  2017年   18篇
  2016年   14篇
  2015年   23篇
  2014年   25篇
  2013年   44篇
  2012年   47篇
  2011年   45篇
  2010年   51篇
  2009年   45篇
  2008年   79篇
  2007年   98篇
  2006年   90篇
  2005年   72篇
  2004年   87篇
  2003年   69篇
  2002年   57篇
  2001年   41篇
  2000年   27篇
  1999年   22篇
  1998年   30篇
  1997年   36篇
  1996年   45篇
  1995年   26篇
  1994年   21篇
  1993年   26篇
  1992年   39篇
  1991年   24篇
  1990年   26篇
  1989年   31篇
  1988年   23篇
  1987年   25篇
  1986年   18篇
  1985年   24篇
  1984年   20篇
  1983年   12篇
  1982年   15篇
  1981年   10篇
  1980年   16篇
  1979年   7篇
  1978年   9篇
  1977年   15篇
  1976年   9篇
  1975年   11篇
  1974年   3篇
  1969年   2篇
排序方式: 共有1554条查询结果,搜索用时 31 毫秒
991.
992.
993.

Introduction

Encephaloceles are considered by most to be a type of neural tube defect characterized by a herniation of the brain and meninges through structural weaknesses in the bony structures of the skull.

Discussion

Many different types of encephaloceles have been classified according to the location of the bony defect. Basal and frontoethmoidal encephaloceles constitute a nasal subclass of encephaloceles, which are herniations from the skull base and ethmoid bone, respectively. Basal encephaloceles are usually occult and can herniate into nasal structures causing obstruction. Frontoethmoidal encephaloceles usually present as a protrusion that is visible at birth and enlarges during crying. Both of these entities are rare with an incidence ranging from 1 in 5,000 to 1 in 40,000 live births around the world with the majority of cases localized in Southeast Asia.

Conclusion

Although cases have been recorded since the sixteenth century, there is still a scarcity of knowledge on the exact causes and factors associated with the development of the disease. Many studies have determined these to be caused by a combination of genetic and environmental factors. Most cases are nonlife threatening and the preferred method of treatment is surgical removal after diagnosis is confirmed with computerized tomography or magnetic resonance imaging. Prognosis is generally positive, especially in the subset of patients with frontoethmoidal encephaloceles.  相似文献   
994.

Introduction

Suprasellar arachnoid cysts can differ from other arachnoid cysts in several ways, making a separate analysis of these cysts worthwhile. Herein, we present the outcome and perform volumetric analysis of six children with suprasellar arachnoid cysts treated with endoscopic ventriculocystocisternostomy in order to evaluate the long-term outcomes.

Patients and methods

Operative and postoperative data were retrospectively reviewed for six patients harboring suprasellar arachnoid cysts. Imaging was then used to follow success of surgical intervention.

Results

Six patients with suprasellar arachnoid cysts underwent ventriculocystocisternostomy. Presenting symptoms were headaches in three patients, developmental delay in another, and an incidental finding in the remaining patients. All patients had enlarged lateral and third ventricles on initial imaging. Average age at presentation was 145.7 months (65.4–250.2). Follow-up was an average of 46.5 months (3–84). The average cyst size was 153.96 cm3 (42.98–369.20) preoperatively and an average of 39.92 cm3 (3.20–101.47) at follow-up.

Conclusions

Based on our experience, suprasellar arachnoid cyst treatment with ventriculocystocisternostomy is an adequate surgical intervention. Suprasellar and third ventricular size does respond to the surgical intervention at long-term follow-up.  相似文献   
995.
996.
997.
998.
PURPOSE: To compare results of 2 statistical methods for identifying factors in claims data that are associated with switching insurance plans between managed care (MC) and indemnity (IN).METHODS: Using claims data from 2 insurance providers in a northeastern city, we analyzed patients aged 18+ with diabetes, asthma, or congestive heart failure (CHF) who were covered any time in 1993-1997 (N = 88,917). Stratifying by initial plan type, we examined predictors of switching from the initial plan type using logistic regression and survival analysis. Covariates included age, time in study (for logistic models), gender, diabetes (yes/no), CHF (yes/no), and asthma (yes/no). Survival analysis accounted for time to switch and allowed time-varying covariates.RESULTS: In logistic regression models, older individuals who were in IN were much less likely to switch into MC. Those in MC were more likely to switch to IN, with the greatest likelihood of switching in ages 60-69 (OR = 4.00, 95% CI = 3.32-4.83). Females were less likely to switch from IN to MC (OR = 0.92, 95% CI = 0.87-0.98), CHF patients were less likely to switch from IN to MC (OR = 0.75, 95% CI = 0.68-0.83), and diabetes patients were less likely to switch from MC to IN (OR = 0.77, 95% CI = 0.62-0.96). Hazard ratios calculated using Cox regression were similar to odds ratios for most covariates. However, some coefficients for diseases were significant in Cox models but not in the logistic models. Cox models took 45 times longer in CPU time than logistic regression models.CONCLUSIONS: Logistic regression was a good approximation to Cox regression in identifying many of the factors in switching insurance plan in these data, at a fraction of the computing time. However, Cox models allowed diseases to be time-varying, and so was more sensitive to identifying significant relationships with disease.  相似文献   
999.
Cumulative exposure to estrogen (E) and progesterone (P) over the menstrual cycle significantly influences the risk of developing breast cancer. Despite the dogma that PR in the breast merely serves as a marker of an active estrogen receptor (ER), and as an inhibitor of the proliferative actions of E, it is now clear that in the breast P increases proliferation independently of E action. We show here that the progesterone receptor (PR) and ER are expressed in different epithelial populations, and target non-overlapping pathways in the normal human breast. In breast cancer, PR becomes highly correlated with ER, and this convergence is associated with signaling pathways predictive of disease metastasis. These data challenge the established paradigm that ER and PR function co-operatively in normal breast, and have significant implications not only for our understanding of normal breast biology, but also for diagnosis, prognosis and/or treatment options in breast cancer patients.  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