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   6640篇
  免费   431篇
  国内免费   13篇
耳鼻咽喉   58篇
儿科学   206篇
妇产科学   323篇
基础医学   838篇
口腔科学   108篇
临床医学   623篇
内科学   1363篇
皮肤病学   101篇
神经病学   568篇
特种医学   122篇
外科学   752篇
综合类   128篇
一般理论   3篇
预防医学   674篇
眼科学   311篇
药学   430篇
中国医学   18篇
肿瘤学   458篇
  2024年   8篇
  2023年   73篇
  2022年   135篇
  2021年   286篇
  2020年   147篇
  2019年   231篇
  2018年   252篇
  2017年   171篇
  2016年   193篇
  2015年   214篇
  2014年   322篇
  2013年   355篇
  2012年   566篇
  2011年   576篇
  2010年   294篇
  2009年   246篇
  2008年   396篇
  2007年   429篇
  2006年   405篇
  2005年   374篇
  2004年   325篇
  2003年   269篇
  2002年   213篇
  2001年   67篇
  2000年   82篇
  1999年   61篇
  1998年   42篇
  1997年   28篇
  1996年   22篇
  1995年   21篇
  1994年   13篇
  1993年   26篇
  1992年   27篇
  1991年   23篇
  1990年   29篇
  1989年   32篇
  1988年   23篇
  1987年   15篇
  1986年   21篇
  1985年   10篇
  1984年   10篇
  1983年   6篇
  1981年   6篇
  1979年   4篇
  1977年   5篇
  1973年   3篇
  1970年   5篇
  1969年   4篇
  1968年   4篇
  1967年   3篇
排序方式: 共有7084条查询结果,搜索用时 0 毫秒
91.
This study investigated the neural basis of individual variation in emotion regulation, specifically the ability to reappraise negative stimuli so as to down-regulate negative affect. Brain functions in young adults were measured with functional Magnetic Resonance Imaging during three conditions: (i) attending to neutral pictures; (ii) attending to negative pictures and (iii) reappraising negative pictures. Resting-state functional connectivity was measured with amygdala and dorsolateral prefrontal cortical (DLPFC) seed regions frequently associated with emotion regulation. Participants reported more negative affect after attending to negative than neutral pictures, and less negative affect following reappraisal. Both attending to negative vs neutral pictures and reappraising vs attending to negative pictures yielded widespread activations that were significantly right-lateralized for attending to negative pictures and left-lateralized for reappraising negative pictures. Across participants, more successful reappraisal correlated with less trait anxiety and more positive daily emotion, greater activation in medial and lateral prefrontal regions, and lesser resting-state functional connectivity between (a) right amygdala and both medial prefrontal and posterior cingulate cortices, and (b) bilateral DLPFC and posterior visual cortices. The ability to regulate emotion, a source of resilience or of risk for distress, appears to vary in relation to differences in intrinsic functional brain architecture.  相似文献   
92.
93.
Chauhan R  Roy TS  Chaudhury A  Shariff A 《Pancreas》2003,27(3):267-269
Variations in the morphology of pancreas are not very common. We observed a rare variant of the uncinate process of the pancreas that extended in the mesentery of the small intestine. After its origin from the lower part of the head of the pancreas, the mesenteric process (MP) passed over the third part of the duodenum to enter the mesentery of the jejunum and ileum and extended up to the level of the pelvic brim. The branches of the superior mesenteric vessels were embedded in the extended MP of the pancreas. This aberrant extension of the pancreas was drained by a narrow duct, which joined the main pancreatic duct inside the head. We did not observe a separate uncinate process arising from the head. On histology normal acini and endocrine cells were observed in the extension. This variant is important as symptoms of pancreatic disease from such extensions may be confused with other commonly encountered acute or chronic abdominal conditions.  相似文献   
94.
It has been reported that the activation of multiple myeloma (MM) cells by CD40 induces proliferation, growth arrest, and apoptosis. To determine whether the biologic sequelae of CD40 activation in MM cells depends on p53 function, we identified temperature-sensitive p53 mutations in the RPMI 8226 (tsp53E285K) and the HS Sultan (tsp53Y163H) MM cell lines. These cells were then used as a model system of inducible wtp53-like function because wild-type-like p53 is induced at permissive (30 degrees C) but not at restrictive (37 degrees C) temperatures. Using p21-luciferase reporter assays, we confirmed that CD40 induces p53 transactivation in RPMI 8226 and HS Sultan cells cultured under permissive, but not restrictive, conditions. Furthermore, CD40 activation of these MM cells under permissive, but not restrictive, temperatures increased the expression of p53 and p21 mRNA and protein. Importantly, CD40 activation induced the proliferation of RPMI 8226 and HS Sultan cells at restrictive temperatures and growth arrest and increased subG1 phase cells at permissive temperatures. These data confirmed that CD40 activation might have distinct biologic sequelae in MM cells, depending on their p53 status.  相似文献   
95.
96.

Background

Dialysis-requiring acute kidney injury (D-AKI) is a serious complication in hospitalized heart failure (HF) patients. However, data on national trends are lacking after 2002.

Methods

We used the Nationwide Inpatient Sample (2002–2013) to identify HF hospitalizations with and without D-AKI. We analyzed trends in incidence, in-hospital mortality, length of stay (LoS), and cost. We calculated adjusted odds ratios (aORs) for predictors of D-AKI and for outcomes including in-hospital mortality and adverse discharge (discharge to skilled nursing facilities, nursing homes, etc).

Results

We identified 11,205,743 HF hospitalizations. Across 2002–2013, the incidence of D-AKI doubled from 0.51% to 1.09%. We found male sex, younger age, African-American and Hispanic race, and various comorbidities and procedures, such as sepsis and mechanical ventilation, to be independent predictors of D-AKI in HF hospitalizations. D-AKI was associated with higher odds of in-hospital mortality (aOR 2.49, 95% confidence interval [CI] 2.36–2.63; P?<?.01) and adverse discharge (aOR 2.04, 95% CI 1.95–2.13; P?<?.01). In-hospital mortality and attributable risk of mortality due to D-AKI decreased across 2002–2013. LoS and cost also decreased across this period.

Conclusions

The incidence of D-AKI in HF hospitalizations doubled across 2002–2013. Despite declining in-hospital mortality, LoS, and cost, D-AKI was associated with worse outcomes.  相似文献   
97.
98.
Role of the funding source: Funding from the NIH was used for support of the participating clinical centers and the coordinating center. The funding source did not participate in the collection or the analysis of the data.BACKGROUND. The β cell killing that characterizes type 1 diabetes (T1D) is thought to begin years before patients present clinically with metabolic decompensation; however, this primary pathologic process of the disease has not been measured.METHODS. Here, we measured β cell death with an assay that detects β cell–derived unmethylated insulin (INS) DNA. Using this assay, we performed an observational study of 50 participants from 2 cohorts at risk for developing T1D from the TrialNet Pathway to Prevention study and of 4 subjects who received islet autotransplants.RESULTS. In at-risk subjects, those who progressed to T1D had average levels of unmethylated INS DNA that were elevated modestly compared with those of healthy control subjects. In at-risk individuals that progressed to T1D, the observed increases in unmethylated INS DNA were associated with decreases in insulin secretion, indicating that the changes in unmethylated INS DNA are indicative of β cell killing. Subjects at high risk for T1D had levels of unmethylated INS DNA that were higher than those of healthy controls and higher than the levels of unmethylated INS DNA in the at-risk progressor and at-risk nonprogressor groups followed for 4 years. Evaluation of insulin secretory kinetics also distinguished high-risk subjects who progressed to overt disease from those who did not.CONCLUSION. We conclude that a blood test that measures unmethylated INS DNA serves as a marker of active β cell killing as the result of T1D-associated autoimmunity. Together, the data support the concept that β cell killing occurs sporadically during the years prior to diagnosis of T1D and is more intense in the peridiagnosis period.TRIAL REGISTRATION. Clinicaltrials.gov NCT00097292.FUNDING. Funding was from the NIH, the Juvenile Diabetes Research Foundation, and the American Diabetes Association.  相似文献   
99.
Goldenhar syndrome, a variant of hemifacial microsomia, is a well-known developmental anomaly of maxillofacial skeleton that is apparent at birth. The first and second branchial arch involvement during early embryonic development results in a wide spectrum of anomalies that may include macrostomia and lateral facial clefts. Though clefts of the orofacial region are among the most common congenital facial defects, the occurrence of lateral facial clefts (Tessier 7 cleft) in conditions such as the Goldenhar syndrome, is very rare (<5%). The lateral facial cleft, which results because of improper development of the perioral muscles of the face, gives an appearance of macrostomia giving rise to potential psychological, aesthetic and feeding problems. This clinical report describes the closure of a Tessier 7 cleft and the use of distraction osteogenesis to treat mandibular asymmetry in an 11-year-old female patient with Goldenhar’s syndrome.  相似文献   
100.
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