全文获取类型
收费全文 | 82832篇 |
免费 | 5591篇 |
国内免费 | 658篇 |
专业分类
耳鼻咽喉 | 856篇 |
儿科学 | 1929篇 |
妇产科学 | 1233篇 |
基础医学 | 11263篇 |
口腔科学 | 1596篇 |
临床医学 | 8315篇 |
内科学 | 18010篇 |
皮肤病学 | 1740篇 |
神经病学 | 8181篇 |
特种医学 | 3770篇 |
外国民族医学 | 16篇 |
外科学 | 12343篇 |
综合类 | 1576篇 |
现状与发展 | 1篇 |
一般理论 | 15篇 |
预防医学 | 4911篇 |
眼科学 | 1319篇 |
药学 | 5487篇 |
6篇 | |
中国医学 | 689篇 |
肿瘤学 | 5825篇 |
出版年
2023年 | 698篇 |
2022年 | 1329篇 |
2021年 | 2476篇 |
2020年 | 1504篇 |
2019年 | 2097篇 |
2018年 | 2453篇 |
2017年 | 1866篇 |
2016年 | 2070篇 |
2015年 | 2446篇 |
2014年 | 3105篇 |
2013年 | 3913篇 |
2012年 | 6035篇 |
2011年 | 6068篇 |
2010年 | 3664篇 |
2009年 | 3196篇 |
2008年 | 4931篇 |
2007年 | 5062篇 |
2006年 | 4728篇 |
2005年 | 4572篇 |
2004年 | 4058篇 |
2003年 | 3883篇 |
2002年 | 3543篇 |
2001年 | 1546篇 |
2000年 | 1427篇 |
1999年 | 1368篇 |
1998年 | 818篇 |
1997年 | 655篇 |
1996年 | 545篇 |
1995年 | 430篇 |
1994年 | 424篇 |
1993年 | 337篇 |
1992年 | 655篇 |
1991年 | 626篇 |
1990年 | 572篇 |
1989年 | 521篇 |
1988年 | 547篇 |
1987年 | 441篇 |
1986年 | 444篇 |
1985年 | 434篇 |
1984年 | 355篇 |
1983年 | 266篇 |
1982年 | 193篇 |
1981年 | 160篇 |
1979年 | 257篇 |
1978年 | 158篇 |
1977年 | 174篇 |
1976年 | 158篇 |
1975年 | 144篇 |
1974年 | 175篇 |
1972年 | 151篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Christian Darras 《Tropical medicine & international health : TM & IH》1997,2(4):356-362
Summary For a decade, numerous projects in Bolivia have tried to put in practice the concept of local health systems. But, so far, no significant changes have been made and local health services still are the 'poor relation' of the system. The main components of the project—expansion of health facilities, training of health personnel and institutional decentralization—were not designed to respond to the complexity of the problems encountered. Decentralization was implemented at the level of health districts but not accompanied by redefinition of functions at the central level, and challenged by civil servants' attempts to save their jobs. While training activities did introduce new methods and subjects, they were too often reduced to short workshops or seminars. Health facilities were built without regard for their significance beyond health care. A strategic approach is needed to adapt the planning process to the degree of liberty allowed by society. 相似文献
73.
74.
Christopher R Pryce Andrea C Dettling Marianne Spengler Christian R Schnell Joram Feldon 《Neuropsychopharmacology》2004,56(2):72-79
BACKGROUND: Early environment is a major determinant of long-term mental health, evidenced by the relationship between early-life neglect or abuse and chronically increased vulnerability to developmental psychopathology, including major depressive disorder (MDD). Animal studies can increase understanding of environmentally mediated causal risk processes. We describe how daily deprivation of biological parenting in primate infants disrupts development of homeostatic and reward systems central to MDD. METHODS: Nine breeding pairs of marmoset monkeys provided control twins (CON) and early-deprived twins (ED); the latter were socially isolated for 30-120 min/day on days 2-28. During the first year of life, basal urinary norepinephrine (NE) titers and cardiophysiologic activity were measured. At the end of year 1 (adolescence), automated neuropsychologic tests were conducted to measure responsiveness to changes in stimulus-reward association (simple/reversed visual discrimination learning) and to reward per se (progressive ratio [PR] reinforcement schedule). RESULTS: The ED monkeys exhibited increased basal urinary NE titers and increased systolic blood pressure relative to CON siblings. The ED monkeys required more sessions to reinstate stimulus-oriented behavior following reversal, suggesting increased vulnerability to perceived loss of environmental control; ED monkeys also performed less PR operant responses, indicating that reward was less of an incentive and that they were mildly anhedonic relative to CON. CONCLUSIONS: In marmoset monkeys, neglect-like manipulation of ED leads to chronic changes in homeostatic systems, similar to those in children and adolescents exposed to early-life adversity and in MDD, and to responses to environmental stimuli similar to those that characterize MDD. 相似文献
75.
Catherine Chapon Laurent Lemaire Florence Franconi Laurent Marescaux Pierre Legras Benoit Denizot Jean-Jacques Le Jeune 《Magnetic resonance in medicine》2004,52(4):932-936
The aim of this study was to detect salvageable peri-infarction myocardium by MRI in rats after infarction, using with a double contrast agent (CA) protocol at 7 Tesla. Intravascular superparamagnetic iron oxide (SPIO) nanoparticles and an extracellular paramagnetic CA (Gd-DOTA) were used to characterize the peri-infarction zone, which may recover function after reperfusion occurs. Infarcted areas measured from T1-weighted (T1-w) images post Gd-DOTA administration were overestimated compared to histological TTC staining (52% +/- 3% of LV surface area vs. 40% +/- 3%, P=0.03) or to T2-w images post SPIO administration (41% +/- 4%, P=0.04), whereas areas measured from T2-w images post SPIO administration were not significantly different from those measured histologically (P=0.7). Viable and nonviable myocardium portions of ischemically injured myocardium were enhanced after diffusive Gd-DOTA injection. The subsequent injection of vascular SPIO nanoparticles enables the discrimination of viable peri-infarction regions by specifically altering the signal of the still-vascularized myocardium. 相似文献
76.
Pneumonia is one of the leading causes of morbidity, hospitalization, and mortality in both industrialized and developing countries. In particular, pulmonary infections acquired in the community, and pneumonias arising in the hospital setting, represent a major medical and economic problem and thus a continuous challenge to health care. For the radiologist, it is important to understand that community-acquired pneumonia (CAP) and nosocomial pneumonia (NP) share a number of characteristics, but should, in many respects be regarded as separate entities. CAP and NP arise in different populations, host different spectra of causative pathogens, and pose different challenges to both the clinician and the radiologist. CAP is generally seen in outpatients, is most frequently caused by Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, and Chlamydia, and its radiologic diagnosis is relatively straightforward. NP, in contrast, develops in the hospital setting, is commonly caused by gram-negative bacteria, and may generate substantial problems for the radiologist. Overall, both for CAP and NP, imaging is an integral component of the diagnosis, important for classification and differential diagnosis, and helpful for follow-up. 相似文献
77.
A sexually dimorphic ratio of orbitofrontal to amygdala volume is altered in schizophrenia. 总被引:3,自引:0,他引:3
Raquel E Gur Christian Kohler Bruce I Turetsky Steven J Siegel Stephen J Kanes Warren B Bilker Avis R Brennan Ruben C Gur 《Neuropsychopharmacology》2004,55(5):512-517
BACKGROUND: Neuroanatomic sexual dimorphisms have been correlated with behavioral differences between healthy men and women. We have reported higher orbitofrontal cortex to amygdala ratio (OAR) in women than men. Although gender differences in schizophrenia are evident clinically and correlate with neuroanatomic measures, their relationship to OAR has not been examined. METHODS: Magnetic resonance imaging was performed in 31 neuroleptic-na?ve schizophrenic patients (16 men) and 80 healthy volunteers (34 men), aged less than 50 years. An automated tissue segmentation procedure was combined with expert-guided parcellation of orbitofrontal and amygdala volumes. RESULTS: Men with schizophrenia had increased OAR relative to healthy men, whereas women had decreased OAR. Increased OAR in men with schizophrenia reflected abnormally low amygdala volumes, whereas decreased OAR in women reflected abnormally low orbitofrontal volumes. Less severe negative symptoms were associated with increased OAR in men but with decreased OAR in women. In men, increased amygdala volume was associated with greater symptom severity, whereas in women higher volumes of both amygdala and orbitofrontal regions were associated with lesser severity of negative symptoms. CONCLUSIONS: These opposite OAR abnormalities, whereby men show feminization and women masculinization, suggest gender-mediated effects of the underlying neuropathologic processes. The correlations with symptom severity suggest that neuroanatomic abnormalities in OAR reflect compensatory brain changes. 相似文献
78.
Exclusive elemental enteral diet in cortico-resistant and cortico-dependent forms of Crohn's disease
Y Le Quintrec J Cosnes M Le Quintrec J F Contou P Baumer J Bellanger J P Gendre 《Gastroentérologie clinique et biologique》1987,11(6-7):477-482
The aim of this study was to investigate the value of elemental diet in steroid-resistant and steroid-dependent Crohn's disease. Elemental diet (Vivonex HN, 39.4 +/- 9.2 kcal/kg/d) was delivered through a nasogastric tube at a constant rate. Twenty therapeutic periods lasting from 20 to 74 days (median, 32 days) were undertaken in 18 patients. Elemental diet was well tolerated. Mean values of hemoglobin, serum albumin, and serum transferrin increased significantly through the therapeutic period; body weight and anthropometric data did not change significantly. The short-term response to elemental diet was excellent in 11 cases, demonstrated by achievement of clinical remission and steroid withdrawal; six patients had an incomplete remission and remained slightly active or had to be maintained under low dose steroids; three patients did not respond to therapy and had to be operated upon. During the follow-up (6-30 months), 8 patients out of 17 had a relapse. Relapse was controlled by medical therapy in 5 cases and led to surgery in the 3 other cases. We conclude that elemental diet, as total parenteral nutrition, is an effective therapy of steroid-resistant and steroid-dependent Crohn's disease. However, elemental diet does not prevent relapse. 相似文献
79.
Uta Lichter-Konecki Christian Benninger Werner E. Brandeis Peter Matthis Dieter Scheffner 《Pediatric hematology and oncology》1987,4(1):77-85
Thirteen children with acute lymphoblastic leukemia (ALL) were investigated before and during cytotoxic therapy. EEG findings were correlated with the clinical course and the therapy protocol and compared with normal data obtained from 295 healthy children. Frequency analysis of the background activity of the EEG revealed an initial slowing of the background activity prior to therapy and further slowing each time a combination of vincristine (VCR), daunorubicine (DAU) or adriblastine (ADR), prednisone (FRED), and L-asparaginase (L-ASP) was administered. The slowing of the background activity correlated only with the administration of these drugs. DAU, ADR, and FRED are not known to influence the EEG; therefore, VCR and L-ASP remain the primary candidates responsible for the central nervous system alteration. 相似文献
80.
C L Le Jeunne F C Hugues J L Dufier Y Munera L Bringer 《Journal of clinical pharmacology》1989,29(2):97-101
B antagonists eye drops are most effective for the treatment of chronic open angle glaucoma. By this way of administration they have a very good systemic bioavailability. Bronchial, and cardiovascular effects of three of these topicals: timolol, carteolol and metipranolol have been evaluated in three parallel groups of asthmatic patients. The three topics induce bronchoconstriction without significant difference between them, and lower heart rate (sometimes very intensely) whatever the B antagonist studied. From these data, it is recommended to practitioners to follow carefully the rules of administration of B blockers, even in eye drops. 相似文献