全文获取类型
收费全文 | 36010篇 |
免费 | 3123篇 |
国内免费 | 1702篇 |
专业分类
耳鼻咽喉 | 376篇 |
儿科学 | 720篇 |
妇产科学 | 615篇 |
基础医学 | 3635篇 |
口腔科学 | 722篇 |
临床医学 | 4323篇 |
内科学 | 5885篇 |
皮肤病学 | 529篇 |
神经病学 | 1882篇 |
特种医学 | 1136篇 |
外国民族医学 | 10篇 |
外科学 | 2885篇 |
综合类 | 5621篇 |
现状与发展 | 10篇 |
一般理论 | 3篇 |
预防医学 | 3119篇 |
眼科学 | 1040篇 |
药学 | 3832篇 |
23篇 | |
中国医学 | 2151篇 |
肿瘤学 | 2318篇 |
出版年
2024年 | 308篇 |
2023年 | 471篇 |
2022年 | 1056篇 |
2021年 | 1480篇 |
2020年 | 1145篇 |
2019年 | 988篇 |
2018年 | 1186篇 |
2017年 | 1079篇 |
2016年 | 1000篇 |
2015年 | 1460篇 |
2014年 | 1795篇 |
2013年 | 1956篇 |
2012年 | 2821篇 |
2011年 | 2980篇 |
2010年 | 2091篇 |
2009年 | 1672篇 |
2008年 | 2202篇 |
2007年 | 2119篇 |
2006年 | 1958篇 |
2005年 | 1803篇 |
2004年 | 1412篇 |
2003年 | 1305篇 |
2002年 | 1222篇 |
2001年 | 951篇 |
2000年 | 898篇 |
1999年 | 696篇 |
1998年 | 294篇 |
1997年 | 282篇 |
1996年 | 237篇 |
1995年 | 226篇 |
1994年 | 153篇 |
1993年 | 117篇 |
1992年 | 231篇 |
1991年 | 194篇 |
1990年 | 164篇 |
1989年 | 159篇 |
1988年 | 135篇 |
1987年 | 110篇 |
1986年 | 101篇 |
1985年 | 67篇 |
1984年 | 49篇 |
1983年 | 30篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 15篇 |
1977年 | 17篇 |
1976年 | 11篇 |
1974年 | 11篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Mohammed SI Dhawan D Abraham S Snyder PW Waters DJ Craig BA Lu M Wu L Zheng R Stewart J Knapp DW 《Molecular cancer therapeutics》2006,5(2):329-336
More than 14,000 people die from invasive transitional cell carcinoma (TCC) of the urinary bladder yearly in the United States. Cyclooxygenase (COX)-inhibiting drugs are emerging as potential antitumor agents in TCC. The optimal in vitro or in vivo systems to investigate COX inhibitor antitumor effects have not been defined. The purpose of this study was to determine COX-1 and COX-2 expression and antitumor effects of COX inhibitors in human TCC cell lines (HT1376, RT4, and UMUC3 cells) and xenografts derived from those cell lines. COX-2 expression (Western blot, immunocytochemistry) was high in HT1376, modest in RT4, and absent in UMUC3 cells in vitro. Similarly, COX-2 expression was noted in RT4 but not UMUC3 xenografts. COX-2 expression in HT1376 xenografts was slightly lower than that observed in vitro. None of four COX inhibitors evaluated (celecoxib, piroxicam, valeryl salicylate, and NS398) reduced TCC growth in standard in vitro proliferation assays at concentrations that could be safely achieved in vivo (< or =5 micromol/L). Higher celecoxib concentrations (> or =50 micromol/L) inhibited proliferation and induced apoptosis in all three cell lines. Celecoxib or piroxicam treatment in athymic mice significantly delayed progression of HT1376 xenografts, which express COX-2, but not UMUC3 xenografts that lack COX-2 expression. In conclusion, standard in vitro assays were not useful in predicting COX inhibitor antitumor effects observed in vivo. Athymic mice bearing TCC xenografts provide a useful in vivo system for COX inhibitor studies. Results of this study provide justification for further evaluation of COX inhibitors as antitumor agents against TCC. 相似文献
32.
应用聚合酶链反应(PCR)结合HpaⅡ限制性内切酶消化法(HpaⅡ-PCR)检测58例急性白血病(AL)患儿降钙素(CT)基因的甲基化状态。病例组待检细胞DNA经HpaⅡ消化后,再用两对CT基因特异性引物作PCR扩增,分别产生长度为566bp和1.4kb特异片段。急性淋巴细胞白血病阳性率71.4%(25/35),急性非淋巴细胞白血病78.2%(18/23)。敏感性达10-3。证明CT基因5′高度甲基化是白血病细胞克隆的特异标志。本课题受卫生部、四川省人民医院出国人员基金资助 相似文献
33.
34.
Prior research on callous-unemotional (CU) traits supports a deficit in recognizing fear in faces and body postures. Difficulties recognising others’ emotions may impair the typical behavioural inhibition for violent behaviour. However, recent research has begun to examine other distress cues such as pain. The present study examined emotion recognition skills, including pain, of school-excluded boys aged 11–16 years (N = 50). Using dynamic faces and body poses, we examined the relation between emotion recognition and CU traits using the youth psychopathic traits inventory (YPI) and the inventory of CU traits. Violent delinquency was covaried in regression analyses. Although fearful facial and fearful bodily expressions were unrelated to CU traits, recognition of dynamic pain facial expressions was negatively related to CU traits using the YPI. The failure to replicate a fear and sad deficit are discussed in relation to previous research. Also, findings are discussed in support of a general empathy deficit for distress cues which may underlie the problem behaviour of young males with CU traits. 相似文献
35.
Jeong Sub Lee Ji Kang Park Seung Hyoung Kim Sun Young Jeong Bong Soo Kim Gukmyoung Choi Mu Suk Lee Su Yeon Ko Im-Kyung Hwang 《Journal of neurology》2014,261(4):817-822
The aim of this study was to evaluate whether contrast enhanced fluid attenuated inversion recovery (CE-FLAIR) imaging can be used to predict the severity of meningitis based on leptomeningeal enhancement (LE) score and cerebrospinal fluid signal intensity (CSF-SI) on CE-FLAIR. We retrospectively analyzed data collected from 43 consecutive patients admitted to our hospital due to meningitis. Clinical factors including initial Glasgow Coma Scale (GCS) score, CSF glucose ratio, log CSF protein, log CSF WBC, and prognosis were evaluated. The LE score was semi-quantitatively scored, and we evaluated CSF-SI ratio at the interpeduncular or quadrigerminal cisterns on CE-FLAIR. We evaluated the differences in clinical variables, LE scores and CSF-SI ratios between the recovery and the complication group. We assessed the correlation between clinical variables, LE scores and CSF-SI ratios. The values of log CSF protein, CSF-SI ratio, and LE score were significantly higher in the complication group (p value <0.05). GCS score and CSF glucose ratio were significantly lower in the complication group (p value <0.01). The LE scores had significant negative correlation with GCS scores and CSF glucose ratios (p value <0.001). The LE score was significantly positively correlated with the value of log CSF protein and CSF-SI ratio (p value <0.01). The CSF-SI ratio was negatively correlated with GCS score and CSF glucose ratio (p value <0.01). The CSF-SI ratio was positively correlated with the value of log CSF protein (p value <0.05). Our results suggest that LE score and CSF-SI ratio are well correlated with clinical prognostic factors. We may predict the clinical severity of meningitis by using LE scores and CSF-SI ration on CE-FLAIR imaging. 相似文献
36.
Yichen Zhong Alvaro Mu?oz George J. Schwartz Bradley A. Warady Susan L. Furth Alison G. Abraham 《Journal of the American Society of Nephrology : JASN》2014,25(5):913-917
GFR decline in patients with CKD has been widely approximated using linear models, but this linearity assumption is not well validated. We conducted a matched case-control study in children from the Chronic Kidney Disease in Children (CKiD) cohort ages 1–16 years with mild to moderate CKD to assess whether GFR decline follows a nonlinear trajectory as CKD approaches ESRD. Children (n=125) who initiated RRT (cases) during follow-up were individually matched by CKD stage at baseline and glomerular/nonglomerular diagnosis with children (n=125) who remained RRT-free when the corresponding case initiated RRT (controls). GFR trajectories were compared using log-linear and piecewise log-linear mixed effects models adjusted for baseline characteristics. From study entry to 18 months before RRT, GFR declined 7% faster among cases compared with controls. However, GFR declined 26% faster among cases compared with controls (P<0.001) during the 18 months before RRT. Nonlinearity in the rate of kidney function loss, which was shown in this cohort, may preclude accurate clinical prediction of the timing of RRT and adequate patient preparation. This study should prompt the characterization of predictive factors that may contribute to an acceleration of kidney function decline.GFR is a key measurement of kidney function, and the degree of GFR decline over time is a reflection of the severity of CKD progression. GFR decline has been approximated as linear or log-linear in most analyses of progression, an assumption that has been consistent with available data.1–4 However, many studies rely on relatively short follow-up periods and few repeated measures. Given the convenience of assuming a linear GFR trajectory, which results from the ease of modeling and interpreting linear slopes, few studies have sought to validate the linearity assumption and explore the possibility of nonlinear GFR decline. However, nonlinearity in GFR decline has been observed in some epidemiologic studies,5–7 and the implications on the risk for adverse outcomes have generated interest.8 A CKD cohort study in France found that about one half of its patients experienced nonlinear GFR decline during the last year before dialysis.5 A study by Li et al.9 used a flexible approach to model nonlinearity in GFR trajectories. Li et al.9 found evidence of nonlinear GFR trajectory behavior in adult patients with CKD, and furthermore, the probability of having nonlinear features in an individual trajectory was associated with known risk factors for CKD progression. O’Hare et al.10 found several distinct nonlinear patterns of GFR decline in the 2 years before dialysis initiation in Veterans Affairs patients.Clinical strategies and subsequent patient response to care could potentially benefit from new insights into the variable paths of progression in patients with CKD.10,11 The question of whether characterizing the nonlinearity in the GFR trajectory can assist the identification of risk groups for outcomes, such as ESRD, remains unexplored. The implications on future outcomes of an increased rate of GFR decline could inform clinical decisions about screening frequencies, treatment, or preparation for RRT.The Chronic Kidney Disease in Children (CKiD) study is an ongoing cohort study of children with CKD who, at baseline, had an eGFR between 30 and 90 ml/min per 1.73 m3 and were ages 1–16 years. An end point of the study is RRT defined as transplant or dialysis. To determine whether trajectories of GFR accelerate before RRT, we nested a case-control study, in which cases were children observed to have received RRT and controls were children with CKD who remained RRT-free at the time when the corresponding case initiated RRT.There were 147 children who experienced RRT during follow-up. Each case was matched individually to an eligible control at the time of the case occurrence. The matching factors included baseline CKD stage, glomerular/nonglomerular diagnosis, and, through design, the amount of follow-up time from study entry. Matching was done without replacement, and 22 cases were excluded from the analyses, because no appropriate control was available. We used a random sequence to determine the order of matching. The analysis was, thus, based on 125 matched case-control pairs. Demographic and clinical characteristics of cases and controls at baseline are shown in Characteristics Cases (n=125) Controls (n=125) Age, yr 12.64 (9.23–14.53) 12.33 (8.71–14.74) Sex (girls), N (%) 38 (30.4) 57 (45.6) Race (nonwhite), N (%) 51 (40.8) 36 (28.8) Urine protein/creatinine ratio 1.74 (0.48–4.04) 0.60 (0.26–1.76) Proteinuria, N (%) 0.2≤protein/creatinine ratio<2 56 (46.7) 71 (59.7) Protein/creatinine ratio≥2 51 (42.5) 23 (19.3) Baseline GFRa 32.21 (26.43–39.64) 35.77 (27.86–43.78) Glomerular diagnosis, N (%)a 47 (37.6) 47 (37.6)