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   14077篇
  免费   938篇
  国内免费   38篇
耳鼻咽喉   229篇
儿科学   506篇
妇产科学   368篇
基础医学   2066篇
口腔科学   242篇
临床医学   1660篇
内科学   2532篇
皮肤病学   342篇
神经病学   1701篇
特种医学   319篇
外科学   1392篇
综合类   69篇
一般理论   13篇
预防医学   1122篇
眼科学   239篇
药学   905篇
中国医学   18篇
肿瘤学   1330篇
  2023年   103篇
  2022年   183篇
  2021年   308篇
  2020年   250篇
  2019年   340篇
  2018年   370篇
  2017年   313篇
  2016年   377篇
  2015年   414篇
  2014年   515篇
  2013年   729篇
  2012年   1090篇
  2011年   1044篇
  2010年   640篇
  2009年   562篇
  2008年   878篇
  2007年   917篇
  2006年   898篇
  2005年   853篇
  2004年   795篇
  2003年   722篇
  2002年   685篇
  2001年   108篇
  2000年   71篇
  1999年   126篇
  1998年   167篇
  1997年   137篇
  1996年   104篇
  1995年   111篇
  1994年   73篇
  1993年   79篇
  1992年   64篇
  1991年   75篇
  1990年   63篇
  1989年   46篇
  1988年   49篇
  1987年   33篇
  1986年   46篇
  1985年   42篇
  1984年   41篇
  1983年   46篇
  1982年   46篇
  1981年   28篇
  1980年   38篇
  1979年   38篇
  1978年   24篇
  1977年   28篇
  1976年   34篇
  1974年   24篇
  1972年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a recently described familial cerebrovascular disorder shown to map to chromosome 19q12. Familial hemiplegic migraine has also been shown in some families to map close to the CADASIL locus. The fully developed CADASIL phenotype consists of recurrent strokes developing in the fourth decade, progressing to a pseudobulbar palsy, spastic quadriparesis, and subcortical dementia. In an Irish family 15 members were fully investigated by magnetic resonance scanning; 10 had typical magnetic resonance features of CADASIL. Five members of this family had familial hemiplegic migraine and 4 of these had magnetic resonance evidence of CADASIL. Two other members had migraine with and without aura as a presenting clinical symptom of CADASIL. This disorder has been shown by linkage analysis to map to the CADASIL locus at chromosome 19. The phenotype at presentation of CADASIL in this family was variable and age related and included familial hemiplegic migraine, migraine with and without aura, transient ischemic attacks, strokes, and spinal cord infarction. This family study increases our understanding of the spectrum of clinical manifestations of this underrecognized familial cerebrovascular disorder.  相似文献   
13.
A cDNA encoding a transmembrane 140 kDa isoform of the neural cell adhesion molecule, NCAM, was transfected into the rat glioma cell line BT4Cn. Transfectants with a homogeneously high expression of NCAM-B showed a decreased capacity for penetration of an artificial basement membrane when compared to cells transfected with expression-vector alone or untransfected cells. However, when injected subcutaneously into nude mice, both NCAM expressing cells and control cells produced invasive tumors. Nude mice injected with NCAM positive cells developed tumors with slower growth rates as compared to those induced by NCAM negative cells. This implies that NCAM may not only be involved in adhesive and motile behaviour of glioma cells, but also in their growth regulation.  相似文献   
14.
Effect of positioning on oxygenation in single-lung transplant recipients.   总被引:1,自引:0,他引:1  
BACKGROUND: Many benefits and adverse effects of positioning are related to changes in ventilation and perfusion. A number of unique factors related to the allograft make the effects of positioning difficult to determine in single-lung transplant recipients. OBJECTIVES: To determine the effect of 3 body positions (supine, lateral with allograft lung down, and lateral with native lung down) on oxygenation and blood flow in single-lung transplant recipients in the 24 hours immediately after surgery. METHODS: A quasi-experimental repeated-measures design with stratified assignment to 1 of 3 different sequencing patterns for turning group was used to study 15 transplant recipients, 9 with emphysema and 6 with fibrosis. Oxygenation, ventilation, and blood flow measures (heart rate, blood pressure) were assessed after each turn. The effect of ischemic reperfusion injury was also explored. RESULTS: The oxygenation, ventilation, and bloodflow variables did not differ significantly across group, diagnosis, or time. Oxygenation variables measured when the allograft lung was dependent did not differ significantly from such measurements obtained when the native lung was dependent. CONCLUSIONS: No single position maximizes oxygenation in the immediate postoperative period in single-lung transplant recipients. Although a single standard protocol for positioning cannot be supported, the study does support the idea that transplant recipients can be safely turned in the immediate postoperative period without compromising oxygenation or hemodynamic status.  相似文献   
15.
Cholesteryl ester transfer protein (CETP) greatly affects the metabolism of all lipoprotein classes including low-density lipoprotein (LDL) and high-density lipoprotein (HDL), both known to constitute powerful risk factors for coronary artery disease (CAD). We now report the successful first cloning and characterization of single-chain antibody fragments specific for CETP. A recombinant phage display library was generated using spleen mRNA isolated from BALB/c mice that had been immunized with highly purified CETP. Screening of the library yielded two single-chain antibody fragments with high affinity for CETP, termed 1CL8 and 1CL10, displaying respective KD values of 4.36 x 10(-9) M and 4.64 x 10(-9) M as determined by affinity sensor technology. Amino acid sequence comparison indicated the complementarity-determining regions of the respective heavy chains to be responsible for CETP high affinity binding. Fragment 1CL8 was successfully employed in clinical chemical quantification systems that uncovered an association in humans between plasma CETP concentration and total body fat mass (r=0.50, p<0.002). Because of the demonstrated superb CETP capturing capacity, combined with high binding affinity to CETP, ready access and unlimited supply, 1CL8 and 1CL10 are expected to prove powerful tools for studies on the role of CETP in atherogenesis.  相似文献   
16.
Tension pneumomediastinum after severe vomiting in a 21-year-old female.   总被引:1,自引:0,他引:1  
A 21-year-old female with chronic membranoproliferative nephritis was admitted for suspected esophageal disruption and asthma after severe, prolonged vomiting. At the time of admission she presented with dyspnea, tachypnea, arterial hypotension and tachycardia. Physical examination showed discrete signs of ectopic air at the neck and distended cervical veins. CT-scan of the chest showed severe mediastinal emphysema with compression of the right atrium. After cervical mediastinotomy the cardiorespiratory parameters normalized immediately. Esophagoscopy showed multiple longitudinal mucosal tears between 25 and 45 cm; fluoroscopically, there was no leakage of contrast medium. Following conservative treatment the patient recovered completely and was discharged on day 8.  相似文献   
17.
18.
Sir, With great interest we read the editorial review of Jean etal. [1] on the relationship between hyperphosphataemia and mortalityin end-stage renal disease patients. The authors summarize resultsfrom the large USRDS and DOPPS studies in which associationsof hyperphosphataemia and increased mortality risks were  相似文献   
19.
Zusammenfassung. Ziel: Die psychische Belastung bei Patienten mit akutem Herzinfarkt innerhalb der ersten 48 h auf der Intensivstation des Städtischen Krankenhauses Kiel wird mit Hilfe der Symptom-Checkliste (SCL-90-R) gemessen. Patienten und Methodik: 134 hauptsächlich wegen eines akuten Herzinfarkts aufgenommene Patienten wurden zwischen August 1996 und Juli 1999 randomisiert ausgewählt. Sie füllten einen der Intensivstation angepassten Fragebogen aus, der u. a. neben Fragen zu sozioökonomischen Daten die standardisierten SCL-90-R enthält. Ergebnisse: Erhöhte Mittelwerte zeigten sich vor allem für die Skalen Somatisierung, Ängstlichkeit, Depressivität und GSI (Global Severity Index) bei solchen Patienten, die wenig soziale Unterstützung bekamen und über ein niedriges Einkommen verfügten. Schlussfolgerung: Da für Patienten mit schlechtem sozialen Netzwerk, niedrigem sozialen Status, erhöhter Angst und Depressivität eine schlechtere Prognose hinsichtlich der Mortalität und Wiedereingliederung in den Beruf beschrieben wurde, ist es im prospektiven Verlauf dieser Studie notwendig, gerade diese Patienten hinsichtlich der Entwicklung ihrer Angst zu erfassen und zu behandeln. Abstract. Objective: 134 patients with acute myocardial infarction, who were treated in an intensive care unit (ICU) of a German hospital in Kiel between 1996 and 1999 were selected for the study to examine their psychologic symptoms. Patients and Methods: The patients were asked to fill in the self-report inventory, the Symptom Checklist-90-Revised (SCL-90-R) within the first 48 h after their arrival in the ICU. Results: Patients with a low social status were found to have elevated mean values of the following scales: somatization (0.93), depression (0.66), and anxiety (0.59). The Global Severity Index (GSI) as a global measure of psychologic distress was elevated as well (0.46). Conclusion: Since patients with a limited social network and low social status, increased anxiety and depressive scores have a poor prognosis as to their mortality and their professional reintegration, it it considered necessary for the prospective setting of this study to register particularly those patients in order to treat their anxiety.  相似文献   
20.
In human cadavers we were able to show that the glenohumeral joint is comparable to the model of a physical piston. The labrum glenoidale functions like a valve against atmospheric pressure. It is possible to characterize the behavior of intraarticular negative pressure by the equation (formula; see text). The calculations of the force F of atmospheric pressure tending to resist distraction of the joint surfaces leads to a 95% confidence interval from 6.9 to 22.9 kp. Under a general anesthetic, distraction of the healthy glenohumeral joint also produces negative intraarticular pressure in the area of the fossa glenoidalis in vivo. Joints with a labral tear (Bankart defect) and a chronic instability are not characterized by this phenomenon. A change in intraarticular pressure might stimulate intraarticular pressure receptors. This could be important in functioning as a neuromuscular protection reflex for the joint.  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