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   2689篇
  免费   216篇
  国内免费   11篇
耳鼻咽喉   21篇
儿科学   101篇
妇产科学   112篇
基础医学   410篇
口腔科学   88篇
临床医学   339篇
内科学   548篇
皮肤病学   117篇
神经病学   150篇
特种医学   40篇
外科学   183篇
综合类   52篇
一般理论   4篇
预防医学   222篇
眼科学   70篇
药学   223篇
中国医学   50篇
肿瘤学   186篇
  2024年   7篇
  2023年   49篇
  2022年   146篇
  2021年   223篇
  2020年   164篇
  2019年   189篇
  2018年   188篇
  2017年   107篇
  2016年   140篇
  2015年   115篇
  2014年   156篇
  2013年   187篇
  2012年   245篇
  2011年   233篇
  2010年   115篇
  2009年   81篇
  2008年   113篇
  2007年   103篇
  2006年   87篇
  2005年   90篇
  2004年   59篇
  2003年   31篇
  2002年   30篇
  2001年   4篇
  2000年   1篇
  1999年   6篇
  1998年   2篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   3篇
  1993年   2篇
  1991年   1篇
  1990年   1篇
  1988年   5篇
  1987年   7篇
  1986年   2篇
  1985年   5篇
  1984年   2篇
  1980年   1篇
  1979年   4篇
  1977年   1篇
  1976年   1篇
  1973年   2篇
  1936年   1篇
排序方式: 共有2916条查询结果,搜索用时 46 毫秒
91.
92.
Objective. To determine intrafamilial seropositivity of HBV and HCV and to compare them in families of infected persons with HBV and HCV in Hamadan clinic of hepatitis.Material and methods. In this analytic cross-sectional study, 651 family members of 200 HBV and HCV infection index cases were entered into the study and after signing an informed consent, they were referred to Blood Transfusion Center. With completion of laboratory tests, interviewers filled the questionnaires.Results. One hundred and eighteen (20.5%) and 107 (18.6%) family members were HBsAg and HBcAb positive respectively. 21 (3.6%) were isolated HBcAb positive. Only one person (1.3%) was HCVAb positive. The general rate of infection in family members of HBV infected people (atleast one case) (49.4%) was significantly higher than that of HCV infected people (3.3%), p < 0.001. Interspouses transmission was evaluated and prevalence of interspouses HBV and HCV infection were 32.3 and 8%, respectively.Conclusion. Intrafamilial and interspousal seropositivity of HBV is obviously more than those of HCV. More attention should be paid to screening and risk lowering activities particularly about HBV infected people and their families.  相似文献   
93.
AIM:To evaluate the diagnostic ability of topographic and tomographic indices with Pentacam and Sirius as well as biomechanical parameters with Corvis ST for the detection of clinical and subclinical forms of keratoconus(KCN).METHODS:In this prospective diagnostic test study,70 patients with clinical KCN,79 patients with abnormal findings in topography and tomography maps with no evidence on clinical examination(subclinical KCN),and 68 normal control subjects were enrolled.The accuracy of topographic,tomographic,and biomechanical parameters was evaluated using the area under the receiver operating characteristic curve(AUC)and cross-validation analysis.The Delong method was used for comparing AUCs.RESULTS:In distinguishing KCN from normal,all parameters showed statistically significant differences between the two groups(P<0.001).Indices with the perfect diagnostic ability(AUC≥0.999)were Sirius KCN vertex of back(KVb),Pentacam random forest index(PRFI),Pentacam index of height decentration(IHD),and Corvis integrated tomographic/biomechanical index(TBI).In distinguishing subclinical KCN from normal,Sirius symmetry index of back(SIb;AUC=0.908),Pentacam inferior-superior difference(IS)value(AUC=0.862),PRFI(AUC=0.847),and Corvis TBI(AUC=0.820)performed best.There were no significant differences between the highest AUCs within keratoconic groups(De Long,P>0.05).CONCLUSION:In clinical KCN,all topographic,tomographic,and biomechanical indices have acceptable outcomes in terms of sensitivity and specificity.However,in differentiating subclinical forms of KCN from normal corneas,curvature-based parameters(SIb and IS value)followed by integrated indices(PRFI and TBI)are the most powerful tools for early detection of KCN.  相似文献   
94.
Developments in the fields of lab-on-a-chip and microfluidic technology have benefited nanomaterial production processes due to fluid miniaturization. The ability to acquire, manage, create, and modify structures on a nanoscale is of great interest in scientific and technological fields. Recently, more attention has been paid to the production of core–shell nanomaterials because of their use in various fields, such as drug delivery. Heterostructured nanomaterials have more reliable performance than the individual core or shell materials. Nanoparticle synthesis is a complex process; therefore, various techniques exist for the production of different types of nanoparticles. Among these techniques, microfluidic methods are unique and reliable routes, which can be used to produce nanoparticles for drug delivery applications.

Developments in the fields of lab-on-a-chip and microfluidic technology have benefited nanomaterial production processes due to fluid miniaturization.  相似文献   
95.
96.
97.
98.
Major depression is a common mental disorder among women. A number of studies have demonstrated the association between some nutrients and food items with depression, but the studies on the association of dietary patterns with depression, especially in the Middle East, are rare. Further, the literature examining the relationship between anthropometric status and depression are inconsistent. In this study, 45 women with major depression and 90 patients with no mental disorder participated. We collected dietary intakes by a semi-quantitative food frequency questionnaire, and measured anthropometric indices (weight, height, waist and hip circumferences). Using factor analysis, two major dietary patterns were extracted: Healthy and Unhealthy. After adjusting for confounders, individuals who gained higher scores in healthy dietary pattern, had 84% lower odds of major depression; while the odds of major depression in participants who gained higher scores in unhealthy dietary pattern showed no significant association. No significant association was found between anthropometric indices and major depression. These results suggest that the healthy dietary pattern is significantly associated with lower odds of major depression in adult women. Further researches are needed to confirm these findings.  相似文献   
99.
Although poly (ionic liquids) (PILs) have attracted great research interest owing to their various applications, the performance of nanoporous PILs has been rarely developed in the catalysis field. To this end, a micro–mesoporous PIL with acid–base bifunctional active sites was designed and fabricated by two different polymerization protocols including hydrothermal and classical precipitation polymerization in this paper. Based on our observations, hydrothermal conditions (high temperature and pressure) enabled the proposed sonocatalyst to possess a great porous structure with a high specific surface area (SBET: 315 m2 g−1) and thermal stability (around 450 °C for 45% weight loss) through strengthening cross-linking. In a comparative study, the preferred nanoporous PIL was selected and utilized as the sonocatalyst in a multicomponent reaction of isatins, primary amines, and thioglycolic acid. In the following, a variety of new and known pharmaceutical spiro-4-thiazolidinone derivatives were synthesized at room temperature and obtained excellent yields (>90%) within short reaction times (4–12 min) owing to the substantial synergistic effect between ultrasound irradiation and magnetically separable catalyst.

Sustainable synthesize of a new mesoporous poly (ionic liquid) as acid–base bifunctional catalyst for environmental being preparation of monospiro derivatives has been developed.  相似文献   
100.
Child Psychiatry & Human Development - All children are vulnerable to pedestrian injuries, but previous research suggests children diagnosed with ADHD may have elevated risk. Child pedestrian...  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