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   13719篇
  免费   975篇
  国内免费   47篇
耳鼻咽喉   124篇
儿科学   356篇
妇产科学   336篇
基础医学   2019篇
口腔科学   899篇
临床医学   1001篇
内科学   2873篇
皮肤病学   334篇
神经病学   1396篇
特种医学   296篇
外科学   1389篇
综合类   81篇
一般理论   10篇
预防医学   1557篇
眼科学   127篇
药学   979篇
中国医学   85篇
肿瘤学   879篇
  2023年   139篇
  2022年   266篇
  2021年   518篇
  2020年   367篇
  2019年   504篇
  2018年   568篇
  2017年   399篇
  2016年   409篇
  2015年   453篇
  2014年   669篇
  2013年   736篇
  2012年   1108篇
  2011年   1146篇
  2010年   573篇
  2009年   531篇
  2008年   863篇
  2007年   812篇
  2006年   670篇
  2005年   681篇
  2004年   569篇
  2003年   515篇
  2002年   411篇
  2001年   255篇
  2000年   241篇
  1999年   198篇
  1998年   90篇
  1997年   59篇
  1996年   37篇
  1995年   36篇
  1994年   39篇
  1993年   32篇
  1992年   100篇
  1991年   89篇
  1990年   98篇
  1989年   57篇
  1988年   64篇
  1987年   55篇
  1986年   48篇
  1985年   48篇
  1984年   34篇
  1983年   21篇
  1982年   15篇
  1981年   17篇
  1980年   13篇
  1979年   21篇
  1974年   17篇
  1973年   12篇
  1971年   15篇
  1970年   18篇
  1969年   12篇
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
41.
An experimental study of saphenous flaps in 26 dogs is reported, which confirmed the work of Baek et al. (1985) that venous flaps can survive. In addition, it showed that venous island flaps could survive after division of the venous pedicle proximally or distally, or as free flaps, providing through flow was re-established by venous anastomoses. In this study no flaps survived on a single venous pedicle without through flow. Two successful clinical cases of venous flaps are also reported, in which through flow was re-established by a simple venous anastomosis. One of these flaps threatened to become necrotic until the thrombosed anastomosis was successfully redone.  相似文献   
42.
目的:比较儿童期癌症标准疗法与Ⅲ期随机化临床试验阶段所验证的新疗法,研究新疗法优于或劣于标准疗法的概率;此类临床试验中,纳入患者的民族因素可能对试验结果造成不确定性影响,所以,本文还研究新疗法的成功和失败模式是否与前述不确定性影响之间存在一致性。试验设计:临床观  相似文献   
43.
Cultures ofTrypanosoma (Megatrypanum) freitasi with L929 mouse fibroblasts at 27.5°C were examined by scanning and transmission electron microscopy in an attempt to clarify the processes of colony formation by the epimastigotes and of their attachment to substrata. It was seen that the flagellates occupy intercellular spaces and do not associate with intact fibroblasts. As the trypanosome population increases, ever larger portions of the substratum are cleared of fibroblasts and occupied by conglomerates of epimastigote colonies consisting of about a dozen organisms that attach to the substratum by their anterior extremities and form pyramidal clusters. Attachment of the epimastigotes involves the flagellar membrane, which becomes extraordinarily enlarged and assumes various aspects of broad sheets, filaments and loops over the substratum or along the flagellum, which exhibits a shortened axoneme. Desmosome or hemidesmosome plaques are present when the attachment takes place between membranes or between the membrane and the substratum.Supported by grants from CNPq and FINEP  相似文献   
44.
Sleep disorders in women: clinical evidence and treatment strategies.   总被引:4,自引:0,他引:4  
Sleep disorders are more prevalent in women than in men. Sex hormones modulate sleep-wake behaviors and mood and may contribute to heightened risk across the life cycle of women. Sleep disorders may have a unique expression in women, emerging throughout their reproductive life cycle. These conditions require careful treatment strategy to manage medical, hormonal, and behavioral contributing factors to poor sleep efficiency and impaired quality of life. This review focuses on clinical evidence for sleep disorders in women and discusses existing evidence of risk factors and treatment options for insomnia and sleep-disordered breathing in women.  相似文献   
45.
This randomized clinical trial compared frequencies of exclusive breastfeeding and lactation-related problems during the first 30 days among 74 mothers who received a 30-minute counseling session on breastfeeding technique in the maternity ward, and 137 controls. The frequency of exclusive breastfeeding among mothers who had received intervention was similar to controls by 7 days (79.7% vs 82.5%, respectively) and 30 days (60.8% vs 53.3%). There was no difference between groups in the frequency of sore nipples at 7 and 30 days, in breast engorgement and mastitis, and in the quality of breastfeeding technique at 30 days. Therefore, a single intervention at maternity was not sufficient to improve breastfeeding technique, increase exclusive breastfeeding rates, and reduce the incidence of breastfeeding problems during the first month.  相似文献   
46.
In this oral presentation, the author emphasized the need for individualization of drug treatment, reviewing the most known factors of variability in drug response. The importance of studies of clinical pharmacokinetics was focused. The main parameters for a judgement on the efficacy and virtual tolerability of a medicine, on the basis of its sequential concentrations in the blood after administration, were briefly outlined. The influence of congestive heart failure on the volume of distribution, systemic clearance, elimination half-life and bioavailability, was discussed. The changes that renal failure makes in drug elimination were equally presented, having been pointed the modification of protein binding, volume of distribution, and hepatic elimination. A selection of eight clinical cases was summarily presented, to illustrate the important contribute that can be afforded to practice by pharmacokinetics. The dosing of aminoglycosides and of other drugs with narrow therapeutic ranges was evaluated through some of the examples. A case of complex interferences of heart failure, renal failure and therapeutic hemoperfusion on the kinetics of an antibiotic drug was included. Two cases of intoxications (phenytoin and theophylline), whose management has been greatly improved by repeated drug dosing in blood, were discussed, too. A special call of attention was made to the need the currently practicing physician has of being aware of kinetic characteristics of the drugs he prescribes, and of how can disease modify the body fate of those medicines, and their therapeutic and nontherapeutic effects.  相似文献   
47.
Objective   To profile the expression of all known members of the matrix metalloproteinase ( MMP ), a disintegrin and metalloproteinase with thrombospondin motifs ( ADAMTS ), and tissue inhibitor of metalloproteinases ( TIMP s) gene families in normal cartilage and that from patients with osteoarthritis (OA).
Methods   Human cartilage was obtained from femoral heads at joint replacement for either osteoarthritis or following fracture to the neck of femur. Total RNA was purified and expression of genes assayed using quantitative real-time PCR.
Results   Several members of the above gene families were regulated in OA. Genes increasing in expression in OA were: at P  < 0.001, MMP-13 , MMP-28 , ADAMTS-16 ; at P  < 0.01, MMP-9 , MMP-16 , ADAMTS-2 , ADAMTS-14 and at P  < 0.05, MMP-2 , TIMP-3 , ADAMTS-12 . Genes decreasing in expression in OA were: at P  < 0.001, MMP-1 , MMP-3 , ADAMTS-1 ; at P  < 0.01, MMP-10 , TIMP-1 , ADAMTS-9 and at P  < 0.05, TIMP-4 , ADAMTS-5 , ADAMTS-15 . Correlation analysis revealed that groups of genes across the gene families are co-expressed in cartilage.
Conclusion   This is the first comprehensive expression profile of all known MMP , ADAMTS and TIMP genes in cartilage. Patterns of expression provide a foundation on which to understand mechanisms of gene regulation in OA and potentially for refining the specificity of anti-proteolytic therapies.  相似文献   
48.
This study aimed to investigate whether endothelial cells are damaged and to evaluate fibrinolytic system function in patients with type 2 diabetes. For this proposal, plasma levels of von Willebrand factor (an endothelial marker of injury), homocysteine (an inductor of endothelial injury), D-dimer (a marker of coagulation cascade activation) and plasminogen activator inhibitor-1 (a fibrinolysis marker) were measured in individuals with both type 2 diabetes and high blood pressure, with type 2 diabetes, with high blood pressure and in healthy control individuals. No significant differences among groups were observed for von Willebrand factor and homocysteine plasma levels. The type 2 diabetes and high blood pressure group presented a significant difference to the other groups for D-dimer and also presented high values for plasminogen activator inhibitor-1. The high blood pressure group and type 2 diabetes group presented separately higher values of plasminogen activator inhibitor-1 compared with the control group. High levels of D-dimer and plasminogen activator inhibitor-1 in patients with type 2 diabetes and high blood pressure with normoalbuminuria therefore indicate a state of hypercoagulability and hypofibrinolysis, despite no evident microvascular injury supported by normal levels of von Willebrand factor and homocysteine.  相似文献   
49.
Objectives: Significant variation in emergency department (ED) patient arrival rates necessitates the adjustment of staffing patterns to optimize the timely care of patients. This study evaluated the effectiveness of a queueing model in identifying provider staffing patterns to reduce the fraction of patients who leave without being seen. Methods: The authors collected detailed ED arrival data from an urban hospital and used a Lag SIPP queueing analysis to gain insights on how to change provider staffing to decrease the proportion of patients who leave without being seen. The authors then compared this proportion for the same 39‐week period before and after the resulting changes. Results: Despite an increase in arrival volume of 1,078 patients (6.3%), an average increase in provider hours of 12 hours per week (3.1%) resulted in 258 fewer patients who left without being seen. This represents a decrease in the proportion of patients who left without being seen by 22.9%. Restricting attention to a four‐day subset of the week during which there was no increase in total provider hours, a reallocation of providers based on the queueing model resulted in 161 fewer patients who left without being seen (21.7%), despite an additional 548 patients (5.5%) arriving in the second half of the study. Conclusions: Timely access to a provider is a critical dimension of ED quality performance. In an environment in which EDs are often understaffed, analyses of arrival patterns and the use of queueing models can be extremely useful in identifying the most effective allocation of staff.  相似文献   
50.
The Spanish registry of alpha-1 antitrypsin deficiency was founded in 1993 and became a member of the International Registry (AIR) in 1999. We describe the updating process following its incorporation into AIR and compare the data collected in the first period (1993–1999) and the second period (1999–2005), during which time patients were included exclusively by internet.The registry included 301 patients during period 1, 69% males and 46% had a history of smoking. Their mean age was 46 years (SD = 13) and 284 (94%) had the ZZ phenotype, 49% received augmentation therapy. During period 2, 161 new cases were included, 63% of whom were males with a mean age of 44 years (SD = 16). A total of 126 (78%) had the ZZ phenotype. Only 12% received augmentation therapy. A total of 462 different patients were included in both periods. Significant differences were observed in the number of cases with the SZ phenotype and the severity of FEV1 impairment between the two periods.Implementation of an internet-based collection of data did not result in a lower rate of reporting to the registry. However, data from a significant number of patient included in period 1 could not be actualized in the new data base.  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