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   56939篇
  免费   4609篇
  国内免费   149篇
耳鼻咽喉   579篇
儿科学   1572篇
妇产科学   1133篇
基础医学   7866篇
口腔科学   1077篇
临床医学   6228篇
内科学   11398篇
皮肤病学   976篇
神经病学   5808篇
特种医学   1902篇
外国民族医学   11篇
外科学   7704篇
综合类   994篇
一般理论   54篇
预防医学   5151篇
眼科学   1198篇
药学   4135篇
中国医学   108篇
肿瘤学   3803篇
  2023年   391篇
  2022年   622篇
  2021年   1222篇
  2020年   849篇
  2019年   1143篇
  2018年   1393篇
  2017年   1096篇
  2016年   1255篇
  2015年   1334篇
  2014年   1800篇
  2013年   2353篇
  2012年   3655篇
  2011年   3729篇
  2010年   2104篇
  2009年   1778篇
  2008年   3003篇
  2007年   3217篇
  2006年   3023篇
  2005年   2815篇
  2004年   2704篇
  2003年   2350篇
  2002年   2251篇
  2001年   1220篇
  2000年   1178篇
  1999年   1061篇
  1998年   592篇
  1997年   451篇
  1996年   469篇
  1995年   426篇
  1994年   371篇
  1993年   327篇
  1992年   710篇
  1991年   681篇
  1990年   722篇
  1989年   617篇
  1988年   608篇
  1987年   625篇
  1986年   625篇
  1985年   568篇
  1984年   461篇
  1983年   370篇
  1982年   259篇
  1981年   239篇
  1979年   470篇
  1978年   317篇
  1977年   271篇
  1976年   242篇
  1975年   262篇
  1974年   292篇
  1973年   269篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
The Sixth Epilepsy Research Foundation workshop, held in Oxford in March 2006, brought together basic scientists, geneticists, epidemiologists, statisticians, pharmacologists and clinicians to consider progress, issues and strategies for harnessing genetics to improve the understanding and treatment of the epilepsies. General principles were considered, including the fundamental importance of clear study design, adequate patient numbers, defi ned phenotypes, robust statistical data handling, and follow-up of genetic discoveries. Topics where some progress had been made were considered including chromosomal abnormalities, neurodevelopment, hippocampal sclerosis, juvenile myoclonic epilepsy, focal cortical dysplasia and pharmacogenetics. The ethical aspects of epilepsy genetics were reviewed. Principles and limitations of collaboration were discussed. Presentations and their matched discussions are produced here. There was optimism that further genetic research in epilepsy was not only feasible, but might lead to improvements in the lives of people with epilepsy.  相似文献   
62.
The molecular events responsible for controlling cell growth and development, as well as their coordinate interaction is only beginning to be revealed. At the basis of these controlling events are hormones, growth factors and mitogens which, through transmembrane signalling trigger an array of cellular responses, initiated by receptor-associated tyrosine kinases, which in turn either directly or indirectly mediate their effects through serine/threonine protein kinases. Utilizing the obligatory response of activation of protein synthesis in cell growth and development, we describe efforts to work backwards along the regulatory pathway to the receptor, identifying those molecular components involved in modulating the rate of translation. We begin by describing the components and steps of protein synthesis and then discuss in detail the regulatory pathways involved in the mitogenic response of eukaryotic cells and during meiotic maturation of oocytes. Finally we discuss possible future work which will further our understanding of these systems.  相似文献   
63.
There have been major advances in PET technology that cumulatively have helped improve image quality, increased the range of applications for PET, and contributed to the more widespread use of PET. Examples of these technologic advances include whole-body imaging, 3-dimensional imaging, new scintillator materials, iterative reconstruction algorithms, combined PET/CT, and preclinical PET. New advances on the immediate horizon include the reintroduction of time-of-flight PET, which takes advantage of the favorable timing properties of newer scintillators; the integration of PET and MRI scanners into a dual-modality imaging system; and the possibility of further significant improvements in spatial resolution in preclinical PET systems. Sensitivity remains a limiting factor in many PET studies. Although, conceptually, huge gains in sensitivity are still possible, realizing these gains is thwarted largely by economic rather than scientific concerns. Predicting the future is fraught with difficulty; nonetheless, it is apparent that ample opportunities remain for new development and innovation in PET technology that will be driven by the demands of molecular medicine, notably sensitive and specific molecular diagnostic tools and the ability to quantitatively monitor therapeutic entities that include small molecules, peptides, antibodies, nanoparticles, DNA/RNA, and cells.  相似文献   
64.
PURPOSE: Epidermal growth factor receptor is expressed in pediatric malignant solid tumors. We conducted a phase I trial of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in children with refractory solid tumors. PATIENTS AND METHODS: Gefitinib (150, 300, 400, or 500 mg/m2) was administered orally to cohorts of three to six patients once daily continuously until disease progression or significant toxicity. Pharmacokinetic studies were performed during course one (day 1 through 28). RESULTS: Of the 25 enrolled patients, 19 (median age, 15 years) were fully evaluable for toxicity and received 54 courses. Dose-limiting toxicity was rash in two patients treated with 500 mg/m2 and elevated ALT and AST in one patient treated with 400 mg/m2. The maximum-tolerated dose was 400 mg/m2/d. The most frequent non-dose-limiting toxicities were grade 1 or 2 dry skin, anemia, diarrhea, nausea, and vomiting. One patient with Ewing's sarcoma had a partial response. Disease stabilized for 8 to > or = 60 weeks in two patients with Wilms' tumor and two with brainstem glioma (one exophytic). At 400 mg/m2, the median peak gefitinib plasma concentration was 2.2 microg/mL (range, 1.2 to 3.6 microg/mL) and occurred at a median of 2.3 hours (range, 2.0 to 8.3 hours) after drug administration. The median apparent clearance and median half-life were 14.8 L/h/m2 (range, 3.8 to 24.8 L/h/m2) and 11.7 hours (range, 5.6 to 22.8 hours), respectively. Gefitinib systemic exposures were comparable with those associated with antitumor activity in adults. CONCLUSION: Oral gefitinib is well tolerated in children. Development of the drug in combination with cytotoxic chemotherapy will be pursued.  相似文献   
65.
66.
Although toe-to-hand transfer has a defined role in the management of congenital hand deformities, it remains unclear how well children integrate the transferred digits into physiological grasping. We analysed fingertip forces in the precision grip of 13 patients when lifting a test object more than three years after free toe transfer for absent or hypoplastic digits. Clinically, most patients showed normal sensibility of transferred digits, but active motion and pinch strength were limited as compared to the normal hand. For the control of fingertip forces, two key features of the normal two-digit opposition grip were seen in all operated hands: adaptation of grip force to object weight and parallel coordination of lift and grip forces. These physiological grasping strategies developed independently of the patients' age at the time of operation, which ranged from one to 13 years. In four patients, we observed increased tangential load forces with the operated hand due to misalignments in the application of fingertips on the grasp surfaces. Such forces lead to increased grip force requirements on both fingers that may overload transferred digits with limited motor function. The need for optimal alignment of the grip axis during toe-transfer surgery is emphasised.  相似文献   
67.
Exercise advice is a well established component of the conservative management of intermittent claudication. Supervised programmes of exercise remain relatively uncommon and are provided mainly in secondary care. This review outlines the evidence for the effectiveness of different exercise regimens and the relative benefits of exercise therapy, where comparisons have been made with medical therapy, angioplasty and surgery.  相似文献   
68.
BACKGROUND: Past receiver operating characteristic (ROC) studies have demonstrated that single photon emission computed tomography (SPECT) perfusion imaging by use of iterative reconstruction with combined compensation for attenuation, scatter, and detector response leads to higher area under the ROC curve (A(z)) values for detection of coronary artery disease (CAD) in comparison to the use of filtered backprojection (FBP) with no compensations. A new ROC study was conducted to investigate whether this improvement still holds for iterative reconstruction when observers have available all of the imaging information normally presented to clinical interpreters when reading FBP SPECT perfusion slices. METHODS AND RESULTS: A total of 87 patient studies including 50 patients referred for angiography and 37 patients with a lower than 5% likelihood for CAD were included in the ROC study. The images from the two methods were read by 4 cardiology fellows and 3 attending nuclear cardiologists. Presented for the FBP readings were the short-axis, horizontal long-axis, and vertical long-axis slices for both the stress and rest images; cine images of both the stress and rest projection data; cine images of selected cardiac-gated slices; the CEQUAL-generated stress and rest polar maps; and an indication of patient gender. This was compared with reading solely the iterative reconstructed stress slices with combined compensation for attenuation, scatter, and resolution. With A(z) as the criterion, a 2-way analysis of variance showed a significant improvement in detection accuracy for CAD for the 7 observers (P = .018) for iterative reconstruction with combined compensation (A(z) of 0.895 +/- 0.016) over FBP even with the additional imaging information provided to the observers when scoring the FBP slices (A(z) of 0.869 +/- 0.030). When the groups of 3 attending physicians or 4 cardiology fellows were compared separately, the iterative technique was not statistically significantly better; however, the A(z) for each of the 7 observers individually was larger for iterative reconstruction than for FBP. Compared with results from our previous studies, the additional imaging information did increase the diagnostic accuracy of FBP for CAD but not enough to undo the statistically significantly higher diagnostic accuracy of iterative reconstruction with combined compensation. CONCLUSIONS: We have determined through an ROC investigation that included two classes of observers (experienced attending physicians and cardiology fellows in training) that iterative reconstruction with combined compensation provides statistically significantly better detection accuracy (larger A(z)) for CAD than FBP reconstructions even when the FBP studies were read with all of the extra clinical nuclear imaging information normally available.  相似文献   
69.
70.
Emphysematous pyelonephritis is a severe life-threatening infection which continues to carry significant morbidity and mortality. We present a case recently managed at our institution by laparoscopic nephrectomy. The patient survived, and in comparison to some of the more conventionally managed patients in the literature, made an extremely speedy recovery. We would advocate this option to be seriously considered when patients are suitable and appropriately trained surgeons are available.  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