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   2722086篇
  免费   195435篇
  国内免费   11861篇
耳鼻咽喉   37172篇
儿科学   82910篇
妇产科学   72272篇
基础医学   396848篇
口腔科学   74773篇
临床医学   247018篇
内科学   526510篇
皮肤病学   58615篇
神经病学   209989篇
特种医学   101359篇
外国民族医学   601篇
外科学   408597篇
综合类   70229篇
现状与发展   36篇
一般理论   909篇
预防医学   200868篇
眼科学   64271篇
药学   208323篇
  68篇
中国医学   11214篇
肿瘤学   156800篇
  2021年   25415篇
  2019年   24386篇
  2018年   33339篇
  2017年   25467篇
  2016年   27820篇
  2015年   32484篇
  2014年   45303篇
  2013年   63703篇
  2012年   88438篇
  2011年   94110篇
  2010年   56052篇
  2009年   52200篇
  2008年   85919篇
  2007年   91706篇
  2006年   92253篇
  2005年   89547篇
  2004年   83920篇
  2003年   80696篇
  2002年   77848篇
  2001年   130229篇
  2000年   133647篇
  1999年   112494篇
  1998年   32324篇
  1997年   28177篇
  1996年   27918篇
  1995年   26183篇
  1994年   23990篇
  1993年   22278篇
  1992年   84465篇
  1991年   81697篇
  1990年   79474篇
  1989年   76717篇
  1988年   70346篇
  1987年   68790篇
  1986年   64129篇
  1985年   61257篇
  1984年   44805篇
  1983年   37817篇
  1982年   22012篇
  1979年   40272篇
  1978年   28273篇
  1977年   23643篇
  1976年   22164篇
  1975年   23994篇
  1974年   28686篇
  1973年   27170篇
  1972年   25538篇
  1971年   24343篇
  1970年   22389篇
  1969年   21471篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Since the introduction of in vitro fertilization in 1978, reproductive medicine and its associated scientific fields have developed rapidly. In Germany, progress in this field is impeded by the German Embryo Protection Act. Exemplary are the prohibition of embryo selection and the ban on genetic testing of the pre-implantation embryo. Nevertheless, infertility treatment outcome has to be optimized within the framework of this law, with the aim of making treatment more efficient, lowering the incidence of multiple gestations, making ovarian hyperstimulation safer, as well as reducing the financial costs for the couple.  相似文献   
993.
Résumé: La rémission du cancer peut être l’occasion pour certains patients d’une réelle détresse émotionnelle ainsi que d’une désadaptation psychologique appelées: syndrome de Lazare. Nous émettons trois hypothèses explicatives quant à la survenue de tels troubles. La première confronte l’issue du cancer aux concepts psychanalytiques de dette et de masochisme. La deuxième envisage les symptômes sous l’angle d’une réaction de sevrage. Et la dernière évoque le contrecoup traumatique des traitements.Dossier: «Cliniques du cancer»  相似文献   
994.
Synovialsarkome sind mitunter schwierig von anderen Spindelzellsarkomen zu unterscheiden. In diesen Fällen kann der Nachweis einer t(X;18) Translokation unter Verwendung der FISH und RT-PCR helfen. Die vorliegende Arbeit wurde unter der Fragestellung durchgeführt, ob bei Synovialsarkom-verdächtigen Tumoren der simultane Einsatz beider Methoden zum Translokationsnachweis erforderlich ist oder ob eine der Methoden ausreicht.In die Studie wurde Paraffin-eingebettetes Tumorgewebe von 53 Patienten einbezogen, bei denen nach Lichtmikroskopie und Immunhistochemie der Verdacht auf das Vorliegen eines Synovialsarkoms bestand. Es erfolgte der Nachweis von t(X;18) mittels FISH und RT-PCR.  相似文献   
995.
996.
The atomic rearrangement cascade that follows the electron-capture decay process in low-Z radionuclides involves X-rays which have high photoelectric interaction probabilities. When the K-shell binding energy of the ionized atom (e.g., hydrogen) is significantly lower than the energy of the X-ray photon, the detector response to a photon-equivalent energy electron and the whole photoionization process are very similar. This is not the case when the scintillator cocktail contains larger atoms (e.g., oxygen and phosphorus in Ultima Gold). For larger Z atoms, the reduced energy of the whole photoionization process is less than the reduced energy of the interacting photon due to the nonlinear effects of ionization quenching. This paper shows the convenience of including a more detailed simulation of the photoionization process in the atomic rearrangement detection model for electron-capture nuclides such as (55)Fe, (51)Cr and (54)Mn. The need for more elaborate atomic rearrangement models is a consequence of the analysis of (125)I data.  相似文献   
997.
998.
Intracranial pathology is a common and important complication in extremely low birth weight babies. Lenticulostriate vasculopathy (LSV) is an abnormal finding on cranial ultrasounds of sick babies and has been associated with congenital infection, chromosomal aberration and twin-to-twin transfusion. We describe a previously unreported situation of LSV being detected in both donor and recipient twin. This pair of monochorionic, diamniotic twins was admitted to the Neonatal Intensive Care Unit at 28 weeks of gestation. The mother underwent an emergency caesarean section because ultrasound and Doppler studies showed stage III twin-to-twin transfusion syndrome. The first twin weighed 998 g and second twin weighed 600 g. The first twin had an uneventful stay, whereas the second twin needed prolonged continuous positive airway pressure and indomethacin for patent ductus arteriosus. Both of them developed LSV. The clinical significance of this condition on the neuro-developmental outcome of a neonate has not yet been fully determined.  相似文献   
999.
BACKGROUND: In allergic conditions, the degree of skin test reactivity does not always correlate with the severity of clinical symptoms. Additional factors may contribute to the reported symptom severity. OBJECTIVES: To investigate the association between the magnitude of the skin prick test (SPT) response and the reported symptom severity in patients with allergic rhinitis and the possible modifying role of psychological factors. METHODS: One hundred four patients with allergic rhinitis and 23 with non-allergic rhinitis, classified according to their SPT response to 19 aeroallergens, were asked to rate the severity of five symptoms and to indicate whether their symptoms intensified on exposure to five common aeroallergens. They also completed a psychological questionnaire. Results Reported symptom severity of allergic rhinitis did not correlate with weal size for any of the aeroallergens tested or with the number of positive responses on SPT. It was not related to patient age, sex, or education. The reported symptoms severity correlated positively (0.29, P < 0.01) with reported symptom intensification on exposure to allergens. Moreover, both outcomes were positively associated with the psychological factors of hypochondriasis (0.20, P < 0.05 and 0.18, P < 0.05, respectively), and somatic awareness (0.24, P < 0.05 and 0.33, P < 0.01, respectively), but not with neuroticism. CONCLUSIONS: The severity of symptoms experienced by patients with allergic rhinitis is apparently not related to the magnitude of SPT response, but rather to psychological factors of hypochondriasis and somatic awareness. Physicians should be aware of the contribution of psychological factors to patient perceptions of the intensity of symptoms and of the intensification of symptoms on their exposure to allergens.  相似文献   
1000.
OBJECTIVE: To determine the safety and the long-term results of primary stent placement for localized distal aortic occlusive disease. DESIGN: Retrospective observational study. PATIENTS AND METHODS: From July 1998 to July 2005 17 patients (14 female and 3 men, mean age 57 years (39-80)) were treated for intermittent claudication. Five of these patients underwent additional endovascular treatment of focal iliac lesions. RESULTS: Technical success defined as residual stenosis of less than 50% or a trans-stenotic systolic pressure gradient <10% was achieved in 14 of 17 (82%) patients. Major complications included dissection at the puncture site in one patient and thrombosis of additional iliac stents in another patient. Both of these complications were successfully treated. During a mean follow-up of 27 months (range 1-86), four patients had recurrence of symptoms due to in-stent restenoses (n=2), femoral (n=1) or iliac occlusion (n=1), respectively. By Kaplan-Meier analysis, primary aortic hemodynamic patency was 83% at 3 years. Secondary aortic hemodynamic patency was 100%. The primary clinical patency was 68% at 3 years. CONCLUSION: Primary stent placement for distal aortic stenoses is an alternative to surgical treatment because of its high patency and relatively low complication rates.  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