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   6699篇
  免费   387篇
  国内免费   39篇
耳鼻咽喉   79篇
儿科学   183篇
妇产科学   228篇
基础医学   961篇
口腔科学   178篇
临床医学   553篇
内科学   1222篇
皮肤病学   171篇
神经病学   453篇
特种医学   291篇
外科学   906篇
综合类   219篇
一般理论   2篇
预防医学   666篇
眼科学   117篇
药学   542篇
中国医学   66篇
肿瘤学   288篇
  2023年   40篇
  2022年   92篇
  2021年   193篇
  2020年   98篇
  2019年   171篇
  2018年   205篇
  2017年   150篇
  2016年   137篇
  2015年   200篇
  2014年   231篇
  2013年   287篇
  2012年   484篇
  2011年   502篇
  2010年   275篇
  2009年   214篇
  2008年   368篇
  2007年   365篇
  2006年   318篇
  2005年   288篇
  2004年   308篇
  2003年   236篇
  2002年   246篇
  2001年   188篇
  2000年   218篇
  1999年   167篇
  1998年   91篇
  1997年   71篇
  1996年   60篇
  1995年   41篇
  1994年   45篇
  1993年   46篇
  1992年   76篇
  1991年   60篇
  1990年   64篇
  1989年   71篇
  1988年   56篇
  1987年   67篇
  1986年   47篇
  1985年   45篇
  1984年   24篇
  1983年   32篇
  1982年   29篇
  1981年   17篇
  1979年   15篇
  1978年   26篇
  1977年   16篇
  1976年   22篇
  1975年   15篇
  1974年   17篇
  1972年   13篇
排序方式: 共有7125条查询结果,搜索用时 15 毫秒
41.
Congenital nephrogenic diabetes insipidus (NDI) is a rare disease caused most often by mutations in the vasopressin V2 receptor (AVPR2). We studied a family which included a female patient with NDI with symptoms dating from infancy. The patient responded to large doses of desmopressin (dDAVP) which decreased urine volume from 10 to 4 I/day. Neither the parents nor the three sisters were polyuric. The patient was found to be a compound heterozygote for two novel recessive point mutations in the aquaporin-2 (AQP2) gene: L22V in exon 1 and C181W in exon 3. Residue Cys181 in AQP2 is the site for inhibition of water permeation by mercurial compounds and is located near to the NPA motif conserved in all aquaporins. Osmotic water permeability (Pf) in Xenopus oocytes injected with cRNA encoding C181W-AQP2 was not increased over water control, while expression of L22V cRNA increased the Pf to approximately 60% of that for wild-type AQP2. Co-injection of the mutant cRNAs with the wild-type cRNA did not affect the function of the wild-type AQP2. Immunolocalization of AQP2-transfected CHO cells showed that the C181W mutant had an endoplasmic reticulum-like intracellular distribution, whereas L22V and wild-type AQP2 showed endosome and plasma membrane staining. Water permeability assays showed a high Pf in cells expressing wild-type and L22V AQP2. This study indicates that AQP2 mutations can confer partially responsive NDI.   相似文献   
42.
43.
A study of 28 patients receiving a standard regimen of total intravenous nutrition (I.V.N.) for periods of > 14 days has shown the transient development of hypercalciuria in 14 patients (50%). The peak incidence of hypercalciuria occurred in 11 patients (39%) after 1 week of I.V.N. and hypercalciuria persisted for 1–4 weeks. In only one patient was hypercalciuria present at the end of the treatment period. Urine calcium (Ca) and nitrogen (N) excretion rates correlated significantly (r = 0.48 p<0.001) and urine N excretion varied from week to week in parallel with urine Ca excretion in the hypercalciuric group of patients. There was no significant difference in urine Ca excretion between 12 patients who received 3.75 mmol Ca/day and 16 patients who received 8.75 mmol Ca/day. It is concluded that transient hypercalciuria may be related to increased protein catabolism and N excretion and that it probably does not indicate a major problem in mineral metabolism.  相似文献   
44.
A rapid isotachophoretic separation of benzo[ C]phenanthridine alkaloids from CHELIDONIUM MAJUS L. is described. The method allows the determination of sanguinarine and chelerythrine in the presence of other isoquinoline alkaloids in crude alkaloids extracts.  相似文献   
45.
Increasing prevalence of mental health disorders within the Australian population is a serious public health issue. Adequate intake of fruits and vegetables (FV), dietary fibre (DF) and resistant starch (RS) is associated with better mental and physical health. Few longitudinal studies exist exploring the temporal relationship. Using a validated food frequency questionnaire, we examined baseline FV intakes of 5845 Australian adults from the AusDiab study and estimated food group-derived DF and RS using data from the literature. Perceived mental health was assessed at baseline and 5 year follow up using SF-36 mental component summary scores (MCS). We conducted baseline cross-sectional analysis and prospective analysis of baseline dietary intake with perceived mental health at 5 years. Higher baseline FV and FV-derived DF and RS intakes were associated with better 5 year MCS (p < 0.001). A higher FV intake (754 g/d vs. 251 g/d, Q4 vs. Q1) at baseline had 41% lower odds (OR = 0.59: 95% CI 0.46–0.75) of MCS below population average (<47) at 5 year follow up. Findings were similar for FV-derived DF and RS. An inverse association was observed with discretionary food-derived DF and RS. This demonstrates the association between higher intakes of FV and FV-derived DF and RS with better 5 year mental health outcomes. Further RCTs are necessary to understand mechanisms that underlie this association including elucidation of causal effects.  相似文献   
46.
ObjectivesUnderstanding the level of investment needed for the 2021-2030 decade is important as the global community faces the next strategic period for vaccines and immunization programs. To assist with this goal, we estimated the aggregate costs of immunization programs for ten vaccines in 94 low- and middle-income countries from 2011 to 2030.MethodWe calculated vaccine, immunization delivery and stockpile costs for 94 low- and middle-income countries leveraging the latest available data sources. We conducted scenario analyses to vary assumptions about the relationship between delivery cost and coverage as well as vaccine prices for fully self-financing countries.ResultsThe total aggregate cost of immunization programs in 94 countries for 10 vaccines from 2011 to 2030 is $70.8 billion (confidence interval: $56.6-$93.3) under the base case scenario and $84.1 billion ($72.8-$102.7) under an incremental delivery cost scenario, with an increasing trend over two decades. The relative proportion of vaccine and delivery costs for pneumococcal conjugate, human papillomavirus, and rotavirus vaccines increase as more countries introduce these vaccines. Nine countries in accelerated transition phase bear the highest burden of the costs in the next decade, and uncertainty with vaccine prices for the 17 fully self-financing countries could lead to total costs that are 1.3-13.1 times higher than the base case scenario.ConclusionResource mobilization efforts at the global and country levels will be needed to reach the level of investment needed for the coming decade. Global-level initiatives and targeted strategies for transitioning countries will help ensure the sustainability of immunization programs.  相似文献   
47.
48.
49.
Differential susceptibility, a reconceptualization of the diathesis-stress model of psychopathology, describes gene–environment interactions that reflect individual differences in responsiveness to environmental influences, both detrimental and beneficial. This model has been described metaphorically by the classification of orchids, which thrive under optimal care but wither under adverse conditions, and dandelions, which weather broad environmental circumstances but are less responsive to careful cultivation. Etiological research in the field of eating disorders has largely focused on the identification of specific behavioral phenotypes, temperamental traits, genotypes and neurobiological processes that confer risk. In this article, we propose that these putative vulnerability factors represent phenotypes and endophenotypes of a genetic predisposition towards environmental sensitivity. We assert that this sensitivity not only transmits eating disorder risk but also confers resilience, depending on the circumstances. In particular, we propose that differential susceptibility can be used as a framework to organize disparate temperamental and neurobiological findings and their complex interplay with various developmental, environmental and sociocultural influences to increase eating disorder risk and treatment responsiveness. Finally, we assert that viewed through the lens of differential susceptibility, sensitivity can be leveraged to refine our interventions and develop novel treatment and prevention strategies to support favorable outcomes for individuals with eating disorders.  相似文献   
50.
19 patients out of those described in part I were examined by MRI and CT. We quote MRI as an excellent new mean of imaging without exposure to ionising radiation which renders sufficient information about the internal knee-structures without surgical invasion. The signal density for the neoligament as well intraarticular as in the "over the top"-position gives evidence for the ingrowth of mesenchymal structures. The MRI diagnosis was proved by histological examination in 2 cases. Very good correspondence between clinic examination and the CT-images could be found. On top of that the tibial drilling holes could be shown in an excellent way. The CT-scan is a fine instrument to judge the postoperative state of the anterior cruciate ligament. The density measurement inside and outside the bone gives evidence for mesenchymal growth inside the carbon fibre structure and the existence of a new natural ligament.  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