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   28169篇
  免费   1684篇
  国内免费   1268篇
耳鼻咽喉   271篇
儿科学   796篇
妇产科学   475篇
基础医学   5253篇
口腔科学   818篇
临床医学   2541篇
内科学   4900篇
皮肤病学   514篇
神经病学   1339篇
特种医学   527篇
外国民族医学   4篇
外科学   1486篇
综合类   4401篇
现状与发展   5篇
预防医学   2204篇
眼科学   374篇
药学   2733篇
  1篇
中国医学   648篇
肿瘤学   1831篇
  2023年   263篇
  2022年   353篇
  2021年   740篇
  2020年   622篇
  2019年   712篇
  2018年   646篇
  2017年   627篇
  2016年   652篇
  2015年   675篇
  2014年   1320篇
  2013年   1407篇
  2012年   1276篇
  2011年   1645篇
  2010年   1382篇
  2009年   1396篇
  2008年   1482篇
  2007年   1692篇
  2006年   1519篇
  2005年   1541篇
  2004年   1336篇
  2003年   1290篇
  2002年   1106篇
  2001年   958篇
  2000年   892篇
  1999年   841篇
  1998年   732篇
  1997年   572篇
  1996年   470篇
  1995年   597篇
  1994年   501篇
  1993年   352篇
  1992年   266篇
  1991年   197篇
  1990年   123篇
  1989年   81篇
  1988年   64篇
  1987年   50篇
  1986年   47篇
  1985年   100篇
  1984年   93篇
  1983年   91篇
  1982年   76篇
  1981年   65篇
  1980年   64篇
  1979年   32篇
  1978年   39篇
  1977年   22篇
  1976年   22篇
  1975年   22篇
  1974年   16篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
Pancreatic ductal adenocarcinoma (PDAC) remains a leading cause of cancer-related death due to the failure of traditional therapies. In the present study, we attempted to construct a lncRNA-miRNA-mRNA network which may modulate PDAC cell proliferation and Gemcitabine-induced cell apoptosis starting from CDK14, a new member of the CDK family and an oncogene in many cancers. Based on TCGA data, a significant positive correlation was observed between lncRNA MSC-AS1 and CDK14. Moreover, MSC-AS1 expression was upregulated in PDAC tissues. Higher MSC-AS1 expression was correlated with poorer prognosis in patients with PDAC. MSC-AS1 knockdown in Panc-1 and BxPC-3 cells significantly inhibited the cell proliferation. Moreover, miR-29b-3p, which has been reported to act as a tumor suppressor, was predicted to bind to both MSC-AS1 and CDK14. Contrary to MSC-AS1, higher miR-29b-3p expression was correlated to better prognosis in patients with PDAC. In both PDAC cell lines, miR-29b-3p negatively regulated MSC-AS1 and CDK14. As confirmed using luciferase reporter gene and RIP assays, MSC-AS1 served as a ceRNA for miR-29b-3p to counteract miR-29b-mediated CDK14 repression. MSC-AS1 knockdown inhibited CDK14 protein levels and PDAC proliferation and enhanced gemcitabine-induced cell death and apoptosis while miR-29b-3p inhibition exerted an opposing effect; the effect of MSC-AS1 knockdown was partially attenuated by miR-29b-3p inhibition. Taken together, we demonstrated that MSC-AS1/miR-29b-3p axis modulates the cell proliferation and GEM-induced cell apoptosis in PDAC cell lines through CDK14. We provided a novel experimental basis for PDAC treatment from the perspective of lncRNA-miRNA-mRNA network.  相似文献   
12.
In this paper, we use optimal parameter selection technique to develop two models involving single‐vendor–multiple‐buyer supply chain, which are called the dynamic independent optimization (DIO) model and the dynamic synchronized cycles (DSC) model, respectively. These models are, respectively, similar to the traditional static independent policy model and the traditional static synchronized cycle model, except that the deterministic demands of the buyers in the above two static models are now being replaced by the stochastic demands satisfying a Wiener process, which have more real‐life applications. Similar to the above static synchronized cycles model, the synchronization of the supply chain in our DSC model is also achieved by scheduling the delivery days of the buyers and coordinating them with the vendor's production cycle. Finding the optimal expected system costs of the DIO model and the DSC model involves solving optimal parameter selection problems governed by ordinary differential equations, whose final times are continuous decision variables and discrete decision variables, respectively. Computational methods have been developed for solving these problems. Numerical results show that the coordinated policy is better than the independent optimization policy, in terms of minimizing the expected system cost of the entire supply chain. Sensitivity analysis is performed to test the effect of changing the cost coefficients and the value on the performances of these models, where is the ratio of the total mean demand rate of all the buyers over the vendor's production rate.  相似文献   
13.
14.
15.
16.

Context

In most resource-rich countries, a large and growing proportion of older adults with complex needs will die while in a residential aged care (RAC) facility.

Objectives

This study describes the impact of facility size (small/large), ownership model (profit/nonprofit) and provider (independent/chain) on resident comfort, and symptom management as reported by RAC staff.

Methods

This retrospective “after-death” study collected decedent resident data from a subsample of 51 hospital-level RAC facilities in New Zealand. Symptom Management at the End-of-Life in Dementia and Comfort Assessment in Dying at End of life with Dementia (SM-EOLD and CAD-EOLD, respectively) scales were used by RAC staff who were closely associated with 217 deceased residents. Data collection occurred from January 2016 to February 2017.

Results

Results indicated that residents of large, nonprofit facilities experienced greater comfort at the end of life (CAD-EOLD) as indicated by a higher mean score of 37.21 (SD = 4.85, 95% CI = 34.4, 40.0) than residents of small for-profit facilities who recorded a lower mean score of 31.56 (SD = 6.20, 95% CI = 29.6, 33.4). There was also evidence of better symptom management for residents of chain facilities, with a higher mean score for symptom management (SM-EOLD total score) recorded for residents of chain facilities (mean = 28.07, SD = 7.64, 95% CI = 26.47, 29.66) than the mean score for independent facilities (mean = 23.93, SD = 8.72, 95% CI = 21.65, 26.20).

Conclusion

Findings suggest that there are differences in the quality of end-of-life care given in RAC based on size, ownership model, and chain affiliation.  相似文献   
17.
PurposeHirschsprung Disease (HD) is a common congenital intestinal disorder. While aganglionosis most commonly affects the rectosigmoid colon (rectosigmoid HD), outcomes for patients in which aganglionosis extends to more proximal segments (long-segment HD) remain understudied. This study sought to compare postoperative outcomes among newborns with rectosigmoid and long-segment HD.MethodsThe Nationwide Readmission Database was queried from 2016 to 2018 for newborns with HD. Newborns were stratified into those with rectosigmoid or long-segment HD. Those who received no rectal biopsy or pull-through procedure during their newborn hospitalization were excluded. A propensity score-matched analysis (PSMA) of newborns with either type of HD was constructed utilizing 17 covariates including demographics, comorbidities, and congenital-perinatal conditions.ResultsThere were 1280 newborns identified with HD (82% rectosigmoid HD, 18% long-segment HD). Patients with rectosigmoid HD had higher rates of laparoscopic resections (35% vs. 12%) and less frequently received a concomitant ostomy (14% vs. 84%), both p < 0.001. Patients with long-segment HD were more likely to have a delayed diagnosis (12% vs. 5%) and require multiple bowel operations (19% vs. 4%), both p < 0.001. They experienced higher rates of complications, including small bowel obstructions (10% vs. 1%), infections (45% vs. 20%), and Hirschsprung-associated enterocolitis (11% vs. 5%), all p < 0.001. After PSMA, newborns with long-segment HD were found to have a longer length of stay and higher hospitalization costs.ConclusionNewborns with long-segment HD experience significant delays in diagnosis, surgery, and complications compared to those with rectosigmoid HD. This information should be utilized to improve healthcare delivery for this patient population.Type of StudyRetrospective comparative study.Level of EvidenceIII.  相似文献   
18.
19.
20.
ObjectiveTo investigate the plasma fibrinogen gamma‐chain concentration in preeclampsia patients and explore its value in preeclampsia prediction and auxiliary diagnosis.MethodsFollow‐up of pregnant women who regularly attended perinatal care at two hospitals in China was performed, and clinical data and plasma samples were collected at each examination until delivery. The gamma‐chain concentration was detected by Western blotting, and Quantity One Software was used for gamma‐chain grayscale value measurements.ResultsForty‐two patients with preeclampsia and 42 control patients completed the follow‐up. In the control group, the gamma‐chain concentration at 32 weeks of gestation was higher than that at 20 weeks of gestation, but the difference was not statistically significant (p > 0.05). In the experimental group, the gamma‐chain concentration at preeclampsia diagnosis was significantly higher than that at 20 weeks of gestation (p < 0.05). Compared with the control group, the gamma‐chain concentration was higher at 20 weeks of gestation in the experimental group, but the difference was not statistically significant. However, at 32 weeks of gestation and at the time of diagnosis, the gamma‐chain concentration in the experimental group was significantly higher than that in the control group (p < 0.05). At 32 weeks of gestation and at the time of diagnosis, the AUCs from ROC curve analysis of plasma fibrinogen gamma‐chain concentrations were 0.64 and 0.71, respectively.ConclusionPlasma fibrinogen synthesis and degradation were disrupted in preeclampsia patients before and after diagnosis, and gamma‐chain concentration was significantly increased. Plasma fibrinogen gamma chain may be of some value in preeclampsia prediction and auxiliary diagnosis.  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