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   10103篇
  免费   820篇
  国内免费   276篇
耳鼻咽喉   63篇
儿科学   260篇
妇产科学   156篇
基础医学   1649篇
口腔科学   249篇
临床医学   645篇
内科学   1270篇
皮肤病学   190篇
神经病学   484篇
特种医学   345篇
外国民族医学   3篇
外科学   1070篇
综合类   1447篇
现状与发展   2篇
预防医学   499篇
眼科学   93篇
药学   1367篇
  2篇
中国医学   509篇
肿瘤学   896篇
  2023年   120篇
  2022年   149篇
  2021年   318篇
  2020年   313篇
  2019年   341篇
  2018年   308篇
  2017年   351篇
  2016年   347篇
  2015年   369篇
  2014年   640篇
  2013年   677篇
  2012年   627篇
  2011年   805篇
  2010年   662篇
  2009年   715篇
  2008年   572篇
  2007年   572篇
  2006年   556篇
  2005年   437篇
  2004年   384篇
  2003年   331篇
  2002年   224篇
  2001年   155篇
  2000年   126篇
  1999年   90篇
  1998年   98篇
  1997年   88篇
  1996年   56篇
  1995年   68篇
  1994年   39篇
  1993年   57篇
  1992年   27篇
  1991年   36篇
  1990年   33篇
  1989年   19篇
  1988年   31篇
  1987年   23篇
  1986年   19篇
  1985年   50篇
  1984年   55篇
  1983年   54篇
  1982年   35篇
  1981年   36篇
  1980年   33篇
  1979年   34篇
  1978年   24篇
  1977年   25篇
  1976年   16篇
  1975年   17篇
  1973年   15篇
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
1.
Ovarian carcinoma is one of the most lethal malignancies, but only very few prognostic biomarkers are known. The degradome, comprising proteases, protease non-proteolytic homologues and inhibitors, have been involved in the prognosis of many cancer types, including ovarian carcinoma. The prognostic significance of the whole degradome family has not been specifically studied in high-grade serous ovarian cancer. A targeted DNA microarray known as the CLIP-CHIP microarray was used to identify potential prognostic factors in ten high-grade serous ovarian cancer women who had early recurrence (<1.6 years) or late/no recurrence after first line surgery and chemotherapy. In women with early recurrence, we identified seven upregulated genes (TMPRSS4, MASP1/3, SPC18, PSMB1, IGFBP2, CFI – encoding Complement Factor I – and MMP9) and one down-regulated gene (ADAM-10). Using immunohistochemistry, we evaluated the prognostic effect of these 8 candidate genes in an independent cohort of 112 high-grade serous ovarian cancer women. Outcomes were progression, defined according to CA-125 criteria, and death. Multivariate Cox proportional hazard regression models were done to estimate the associations between each protein and each outcome. High ADAM-10 expression (intensity of 2–3) was associated with a lower risk of progression (adjusted hazard ratio (HR): 0.51; 95% confidence interval (CI): 0.29-0.87). High complement factor I expression (intensity 2–3) was associated with a higher risk of progression (adjusted HR: 2.30, 95% CI: 1.17–4.53) and death (adjusted HR: 3.42; 95% CI: 1.72–6.79). Overall, we identified the prognostic value of two proteases, ADAM-10 and complement factor I, for high-grade serous ovarian cancer which could have clinical significance.  相似文献   
2.
《中国现代医生》2019,57(33):43-45+49+169
目的探讨智力障碍相关基因Cdk13对神经轴突伸长的影响。方法通过基因敲除模型、质粒细胞转染等方法,荧光共聚焦显微镜成像技术检测神经元轴突的形态,观察轴突伸长的变化。结果 Cdk12和Cdk13在神经系统中有表达,在敲除Cdk12和Cdk13后轴突长度比对照组减少,两者比较有统计学差异(P0.05),敲除Cdk12和Cdk13基因后Cdk5 mRNA水平降低。结论 Cdk13和Cdk12的表达对神经元轴突的生长至关重要,其失活会引起神经元轴突形态异常,可能是导致智力障碍的病理机制。  相似文献   
3.
目的:观察理气中药经验组方对糖尿病大鼠胃排空延迟的干预作用。方法:雌雄各半成年SD大鼠110只,随机分为正常组(A组)、糖尿病中药组(B组)、糖尿病胃复安组(C组)、糖尿病组(D组)。A组、D组1次/d按10 mL/只予0.9%生理盐水灌胃,B组1次/d按8 mL/只予中药煎剂灌胃,C组1次/d按0.5 mg/只予胃复安片灌胃。喂养12周后,行13C胃排空实验及甲基橙水溶液胃排空实验,观察各组大鼠胃排空情况。结果:糖尿病大鼠胃排空较正常大鼠明显延迟(P0.01),糖尿病大鼠胃排空延迟模型制作成功。糖尿病中药组和糖尿病胃复安组大鼠胃排空较糖尿病组快(P0.01);糖尿病中药组大鼠胃排空较糖尿病胃复安组大鼠快(P0.05)。结论:常规喂养12周后糖尿病大鼠出现胃排空延迟。理气中药陈皮、枳实、木香、香附组方煎剂和胃复安均能促进糖尿病大鼠胃排空,理气中药组方煎剂的效果优于胃复安。  相似文献   
4.
DNA mixture interpretation can produce opposing conclusions by qualified forensic analysts, even within the same laboratory. The long-delayed publication of the National Institutes of Standards and Technology (NIST) study of 109 North American crime laboratories in this journal demonstrates this most clearly. This latest study supports earlier work that shows common methods such as the Combined Probability of Inclusion (CPI) have wrongly included innocent people as contributors to DNA mixtures. The 2016 President's Council of Advisors on Science and Technology report concluded, “In summary, the interpretation of complex DNA mixtures with the CPI statistic has been an inadequately specified—and thus inappropriately subjective—method. As such, the method is clearly not foundationally valid” [7]. The adoption of probabilistic genotyping by many laboratories will certainly prevent some of these errors from occurring in the future, but the same laboratories that produced past errors can also now review old cases with their new software—without additional bench work. It is critical that laboratories adopt procedures and policies to do this.  相似文献   
5.

Introduction

In the phase II/III KEYNOTE-010 study (ClinicalTrials.gov, NCT01905657), pembrolizumab significantly prolonged overall survival over docetaxel in patients with previously treated, programmed death ligand 1–expressing (tumor proportion score ≥ 1%), advanced NSCLC. Health-related quality of life (HRQoL) results are reported here.

Methods

Patients were randomized 1:1:1 to pembrolizumab 2 or 10 mg/kg every 3 weeks or docetaxel 75 mg/m2 every 3 weeks. HRQoL was assessed using European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire (QLC) Core 30 (C30), EORTC QLQ–Lung Cancer 13 (LC13), and EuroQoL-5D. Key analyses included mean baseline-to-week-12 change in global health status (GHS)/quality of life (QoL) score, functioning and symptom domains, and time to deterioration in a QLQ-LC13 composite endpoint of cough, dyspnea, and chest pain.

Results

Patient reported outcomes compliance was high across all three instruments. Pembrolizumab was associated with better QLQ-C30 GHS/QoL scores from baseline to 12 weeks than docetaxel, regardless of pembrolizumab dose or tumor proportion score status (not significant). Compared with docetaxel, fewer pembrolizumab-treated patients had “deteriorated” status and more had “improved” status in GHS/QoL. Nominally significant improvement was reported in many EORTC symptom domains with pembrolizumab, and nominally significant worsening was reported with docetaxel. Significant prolongation in true time to deterioration for the QLQ-LC13 composite endpoint emerged for pembrolizumab 10 mg/kg compared to docetaxel (nominal two-sided p = 0.03), but not for the 2-mg/kg dose.

Conclusions

These findings suggest that HRQoL and symptoms are maintained or improved to a greater degree with pembrolizumab than with docetaxel in this NSCLC patient population.  相似文献   
6.
Parabens are antimicrobial additives found in a wide array of consumer products. However, the halogenated compounds formed from parabens during wastewater disinfection are a potential environmental concern. In order to identify these transformation products and investigate their mechanism of formation, a synthetic route to ethyl parabens labeled with the stable isotope carbon-13 at specific positions within the benzene ring was developed. This efficient two-step procedure starts from commercially available 13C-labeled phenols and involves (1) initial acylation of the phenol via a Houben–Hoesch reaction with trichloroacetonitrile followed by (2) a modified haloform reaction of the resulting trichloromethyl ketone to afford the corresponding 13C-labeled ethyl parabens in 65%–80% overall yield. The scope of the modified haloform reaction was also investigated, allowing for the synthesis of other parabens derived from primary or secondary alcohols, including 13C- and deuterium-labeled esters. In addition, 4-hydroxybenzoic acid can be formed directly from the common trichloromethyl ketone intermediate upon treatment with lithium hydroxide. This protocol complements existing methods for preparing 13C-labeled paraben derivatives and offers the specific advantages of exhibiting complete regioselectivity in the Houben–Hoesch reaction (to form the para-disubstituted product) and avoiding the need for protecting groups in the modified haloform reaction that forms the paraben esters.  相似文献   
7.
IntroductionVon Willebrand factor (vWF) cleaving protease ADAMTS-13 has a key role for maintaining normal size of vWF. A deficiency or dysfunction of vWF cleaving protease is associated with ultra large vWF multimers and thrombotic microangiopathy. Patients with cancers have reduced levels of vWF cleaving protease. In this pilot study, we have evaluated whether or not deficiencies of ADAMTS-13 were present in myelodysplastic syndromes (MDS). Moreover, we assessed if a reduction in basal levels of ADAMTS-13 may play a role in the prognosis of MDS.Patients and MethodsWe measured and compared the levels of vWF cleaving protease ADAMTS-13 in 100 patients with MDS and 35 healthy controls. Patients were divided into 2 groups according to the International Prognostic Scoring System: group I consisting of 44 patients with low-risk MDS and group II of 56 patients with high-risk MDS. Patients with high-risk and low-risk MDS presented significantly lower levels of ADAMTS-13 than controls (P < .001 and P = .0177, respectively). High-risk patients had significantly lower levels of ADAMTS-13 when compared with the low-risk group (P < .001).ResultsWe found that reduced levels of ADAMTS-13 have a relationship with overall survival (P < .001). Statistical analysis showed that ADAMTS-13 correlates with cytogenetics (P < .001) and a tendency of slight correlation with platelet count and basal levels of ADAMTS-13 (R, 0.35; P value, 0.001). Moreover, we found that levels of ADAMTS-13 have correlation with response to treatment (P < .001).ConclusionsADAMTS-13 in MDS might represent a surrogate marker of prognosis, response to therapy, or disease progression. Further studies are needed.  相似文献   
8.
AimTo develop a treatment paradigm for chronic leg ulcers that incorporates new biomarkers of wound healing with currently available therapies.MethodsRecently published data on GM-CSF and MMP-13 as biomarkers of venous leg ulcer (VLU) healing status with accuracies of 92% and 78% respectively, was reviewed along with the wound bed preparation (WBP) theoretical framework for treatment of chronic wounds. The broad categories of wound treatments that align with the WBP concepts were identified. These were then considered in a hierarchical order that initially improves the wound bed and subsequently incorporates more complex advanced wound therapies. Identification of the non-healing status of the wound is the driver to advance through the different treatments.ResultsA point of care test of wound healing status is the key to the systematic use of currently available therapies for chronic leg ulcers in a timely fashion. The different therapies address – debridement, moisture control, bacterial contamination, protease inhibition, formation of granulation tissue, application of growth factors, application of matrix constructs, and application of cellular components. Progression through this hierarchical order of therapies is directed by the leg ulcer remaining in a non-healing state with the previous therapies having been implemented.ConclusionCombining a validated point of care test of wound healing with a systematic approach to wound therapies, has the potential to create a new paradigm of chronic leg ulcer treatment - biomarker directed wound therapy.  相似文献   
9.
10.
目的:从分子水平研究抗纤Ⅰ号方剂治疗肝纤维化的作用机理。方法:利用CCl4、高脂饮食和乙醇等综合因素制造大鼠肝纤维化模型。模型成功后将大鼠随机分为肝纤维化模型组、中药和西药治疗组。分别治疗42 d后,检测各组大鼠肝组织病理学变化、血清肝功能和肝纤维化指标、免疫组化检测肝组织Ⅰ、Ⅲ型胶原的变化、半定量PCR检测肝组织MMP1、TIMP-1 mRNA表达量的变化。结果:中药组肝组织病理学变化明显优于模型组和西药治疗组;血清肝功能指标中药治疗组ALT和AST(108±24,142±23)显著低于模型组(242±34,248±20)和西药对照组(123±39,216±25,P<0.05);肝纤维化指标中药治疗组HA和LN(270±79,62±10)显著低于模型组(769±67,109±26)和西药对照组(346±62,79±13,P<0.05);中药治疗后能够明显减少肝组织Ⅰ、Ⅲ型胶原以及TIMP-1 mRNA的表达量,但MMP1的表达量无显著差异。结论:抗纤Ⅰ号通过下调TIMP-1mRNA减弱对MMP1的抑制作用,使Ⅰ、Ⅲ型胶原的降解增强而使肝纤维化逆转。  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