全文获取类型
收费全文 | 8325篇 |
免费 | 534篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 161篇 |
儿科学 | 311篇 |
妇产科学 | 205篇 |
基础医学 | 1117篇 |
口腔科学 | 378篇 |
临床医学 | 559篇 |
内科学 | 2071篇 |
皮肤病学 | 187篇 |
神经病学 | 603篇 |
特种医学 | 224篇 |
外科学 | 1176篇 |
综合类 | 41篇 |
预防医学 | 786篇 |
眼科学 | 140篇 |
药学 | 471篇 |
中国医学 | 44篇 |
肿瘤学 | 399篇 |
出版年
2023年 | 75篇 |
2022年 | 133篇 |
2021年 | 281篇 |
2020年 | 139篇 |
2019年 | 251篇 |
2018年 | 320篇 |
2017年 | 217篇 |
2016年 | 208篇 |
2015年 | 222篇 |
2014年 | 299篇 |
2013年 | 381篇 |
2012年 | 551篇 |
2011年 | 600篇 |
2010年 | 376篇 |
2009年 | 300篇 |
2008年 | 465篇 |
2007年 | 457篇 |
2006年 | 413篇 |
2005年 | 418篇 |
2004年 | 377篇 |
2003年 | 327篇 |
2002年 | 301篇 |
2001年 | 191篇 |
2000年 | 228篇 |
1999年 | 194篇 |
1998年 | 70篇 |
1997年 | 43篇 |
1996年 | 40篇 |
1995年 | 44篇 |
1994年 | 44篇 |
1993年 | 42篇 |
1992年 | 94篇 |
1991年 | 71篇 |
1990年 | 71篇 |
1989年 | 75篇 |
1988年 | 57篇 |
1987年 | 58篇 |
1986年 | 44篇 |
1985年 | 43篇 |
1984年 | 32篇 |
1983年 | 27篇 |
1979年 | 22篇 |
1978年 | 17篇 |
1976年 | 21篇 |
1975年 | 21篇 |
1974年 | 23篇 |
1973年 | 23篇 |
1971年 | 21篇 |
1970年 | 19篇 |
1969年 | 16篇 |
排序方式: 共有8873条查询结果,搜索用时 0 毫秒
991.
Marilia Brasilio Rodrigues Camargo Maysa Seabra Cendoroglo Luiz Roberto Ramos Maria do Rosario Dias de Oliveira Latorre Gabriela Luporini Saraiva Andrea Lage Nelson Carvalhaes Neto Lara Miguel Quirino Araújo José Gilberto H. Vieira Marise Lazaretti-Castro 《Osteoporosis international》2005,16(11):1451-1460
This cross-sectional study covered 301 individuals over 70 years of age—207 women (W) and 94 men (M)—living in the city of São Paulo, Brazil. Our aims were to evaluate the prevalence of low bone mineral density (BMD) in this population and the possible factors that influence BMD. The subjects were submitted to a bone densitometry scan (DXA) to evaluate the BMD at lumbar spine (LS), femoral neck (FN), trochanter (T), total femur (TF) and total body composition. At the time, the participants filled in a questionnaire about lifestyle habits, diet and medical history, as well as having blood samples taken to check hormone and biochemical levels. Anthropometric parameters were measured. Osteopenia and osteoporosis were defined in accordance with the criteria suggested by the World Health Organization. In the different sites studied, the prevalence of osteopenia and osteoporosis varied, in men ranging 33.3–57.4% and 6.4–16.1%, respectively, and in women ranging 36.6–56.5% and 22.2–33.2%, respectively. Weight was the variable that most strongly correlated with BMD at the proximal femur in both sexes (men, r =0.44–0.52; women, r =0.48–0.52) and with BMD at LS in women ( r =0.44). Height was the parameter that best correlated with BMD at LS in men ( r =0.34). In men follicle-stimulating hormone, growth hormone and glycemia correlated with BMD at T and TF, while plasma albumin only correlated with BMD at T. In women glycemia correlated with BMD at LS, and follicle-stimulating hormone correlated with BMD at FN, T and TF. In conclusion, we found a high prevalence of osteopenia and osteoporosis in this population, with weight being the best predictor of BMD. The prevalence of osteoporosis and osteopenia at FN was as high in men as that observed in women. 相似文献
992.
Prolactin can modulate the adrenal medulla function, but it has not yet been established whether its action is directly exerted on the adrenal medulla cells. In this work, we have studied the effect of several concentrations of prolactin on the synthesis, storage and release of norepinephrine and epinephrine using cultured bovine adrenal chromaffin cells. In these cells, prolactin inhibited the activity of tyrosine hydroxylase, the rate-limiting enzyme in the catecholamine synthesis, in a dose-dependent manner, from a concentration above 50 ng/ml of prolactin in the incubation medium. Surprisingly, this dose-dependent decrease was not accompanied by changes in the catecholamine release, since the secretion of both norepinephrine and epinephrine as well as the total catecholamine secretion were not significantly altered by the different prolactin concentrations. Moreover, the cellular content of both catecholamines was not altered by prolactin. In summary, these observations allow us to conclude that prolactin exerts a direct inhibitory effect on the tyrosine hydroxylase activity in cultured adrenal chromaffin cells without altering catecholamine release. 相似文献
993.
J B Schwartz M H Cheng A D Ramos R J Merritt A C Platzker 《Journal of perinatology》1990,10(4):376-379
Plasma ammonia concentration in neonates has routinely been determined using arterial or venous blood. Expected plasma ammonia values in capillary blood obtained by heelstick have not been determined. We compared ammonia levels in 20 sets of plasma from simultaneously drawn arterial, venous, and capillary blood in a group of neonates receiving total parenteral nutrition. Mean ammonia concentrations in venous (107 +/- 44) and capillary blood (112 +/- 33) were 45% and 51% higher, respectively, than corresponding arterial (74 +/- 22) values (P less than .001). Ammonia levels in blood obtained by venipuncture (Ven), however, did not correlate consistently with arterial (Art) values (r = .43; Art = 51 + 0.21 Ven; P greater than .05). In contrast, ammonia levels in capillary blood (Cap) correlated well with arterial values (r = .86; Art = 10.3 + 0.6Cap; P less than .001). Ammonia levels in neonates may be reliably interpreted using the latter regression equation when blood for analysis is obtained by a properly performed heelstick, allowing the preservation of arteries and veins, and sparing the infant from repetitive needle punctures. Ammonia levels in blood obtained by venipuncture do not adequately correlate with arterial values and therefore may be therapeutically misleading. 相似文献
994.
Rosa María Ramos Rodríguez Karla Sandoval Mendoza 《Pan American journal of public health》2007,22(4):260-267
OBJECTIVES: To further understanding of the nutritional transition process by studying possible changes over time in the nutritional status of the Triqui ethnic group in the state of Oaxaca, Mexico. METHODS: A retrospective study was conducted using anthropometric data available from three prior studies (end of the 19th century, 1940, and 2002). Means and z scores for height, weight, and body mass index of Triqui adults were calculated using Frisancho reference data. Statistical analyses of the results were performed with Student's t and chi-square tests. Sociocultural information was collected through interviews and direct observations, as well as from the available literature. RESULTS: The height of Triqui adults has remained very low. A majority of Triqui women were found to be short or very short; this, coupled with the low level of education and high rates of illiteracy and monolingualism, is indicative of a culture that does not favor females. The appearance of overweight and obesity among the men studied in 2002, relative to those studied in 1940, is cause for concern. Overweight was also recorded among the women in 2002. CONCLUSIONS: Despite the limitations shared by all retrospective studies, these results confirm that the nutritional status of the Triquis is different now from what it was 60 years ago and that these changes are related to the cultural changes the group is experiencing. To further understand this epidemiologic phenomenon, where malnutrition and obesity coexist, cross-disciplinary studies are needed to analyze the biological, social, and cultural factors involved, so that culturally-appropriate measures can be adopted. 相似文献
995.
J. D. A. Ramos N. Cheong† B. W. Lee K. Y. Chua 《Clinical and experimental allergy》2003,33(4):511-517
BACKGROUND: The identification of immunodominant peptides containing the IgE and IgG epitopes on allergen molecules is an important step in understanding the interaction of the allergen with the immune system and, thus, essential for the development of effective immunotherapeutic and diagnostic reagents. The present study aimed to map the IgE and IgG immunodominant peptides of Blomia tropicalis (Bt) allergen Blo t 11, a high molecular weight allergen homologous to paramyosin, exhibiting important allergenic activity. METHODS: Eleven overlapping fragments of Blo t 11 cDNA gene were expressed as glutathione s-transferase (GST) fusion peptides, which were affinity-purified using the glutathione-Sepharose column. Human IgE and IgG immunodominant peptides were determined by dot blot immunoassay using crude Bt extract-positive sera from asthmatic patients. Evaluation of allergenicity, specific hIgG subclass analysis, and cross- and self-inhibition studies were determined by enzyme-linked immunosorbent assay. RESULTS: Blo t 11 contains multiple IgE and IgG immunodominant peptides scattered throughout the molecule. The dominant IgE and IgG peptides were mapped at amino acid positions 336-557 and 698-875, respectively. An immunodominant peptide (fD) registered a higher percentage of IgE and IgG reactivity compared to the rFL-Blo t 11. Significant serum levels of Blo t 11- and fD-specific IgG1, IgG2 and IgG4, but not IgG3 were detected in the Bt extract-positive sera tested. Cross-inhibition study revealed the rFL-Blo t 11 was significantly inhibited by fD. CONCLUSION: The IgE and IgG immunodominant peptides of Blo t 11 have been mapped. Our data suggest that utilization of Blo t 11 fragment(s) or chimeric fusion fragments containing IgE and IgG epitopes could be a better alternative in the development of diagnostic and therapeutic reagents for mite allergy. 相似文献
996.
The use of the Clinical Interview Schedule for the evaluation of mental health in the aged community 总被引:1,自引:0,他引:1
As a part of a survey to study the health and living conditions of the elderly population, a random sample of residents aged 65 and over are examined using the Clinical Interview Schedule (CIS) in order to evaluate their psychiatric status. The aim of this study is to evaluate this standard method of assessment as a case-identification instrument in our country. The schedule was completed by 91 subjects. It is easily administered, easily scored, and economical on time. Its completion rate is high. The weighted total scores (WTS) range from 0 to 48. Using the case criteria defined by Cooper & Schwarz (1982), 27 subjects (30%) are considered cases and 64 (70%) are regarded as non-cases. The sensitivity coefficients for the WTS are examined against the overall severity rating at different cut-off points. The optimum cut-off can be anywhere between 16 and 20 points. The WTS has higher validity coefficients to detect the following diagnostic categories (sensitivity, specificity): normals (100%,-); personality (100%, 92%) and affective disorders (100%, 75%). In general the CIS items are given low ratings. Psychotic symptoms are rarely found in this sample. One main problem arose: the item depersonalization is misunderstood by some patients probably because of interpreting it as an upsetting memory disturbance. 相似文献
997.
Angelita Habr-Gama M.D. Afonso H. S. e Sousa Jr. M.D. José Manuel Correia Roveló M.D. Jayme Vital Santos Souza M.D. Fernando Benício M.D. Francisco S. P. Regadas M.D. Cláudio Wainstein M.D. Túlio Marcos Rodrigues da Cunha M.D. Carlos Frederico S. Marques M.D. Renato Bonardi M.D. José Reinan Ramos M.D. Luiz Cláudio Pandini M.D. Desidério Kiss M.D. 《Journal of gastrointestinal surgery》2003,7(6):809-813
The purpose of the present study was to determine the value of circular emorrhoidectomy (procedure for prolapse and hemorrhoids
[PPH]) on the basis of data collected prospectively during the initial experience of a group of Latin American surgeons. Between
2000 and 2001, PPH was performed using a circular stapler in 177 patients who had third- and fourth-degree hemorrhoidal disease.
The average age of the patients was 47.7 years (range 26 to 85 years). Anal bleeding was the most common preoperative complaint
(93.2%) followed by anal pain (60.2 %), anal itching (43%), and constipation (41 %). Hemorrhoids were classified as third
degree in 132 patients (74%) and fourth degree in 45 patients (25.4%). Skin tags were detected in 86 patients (48.8%) and
rectocele in 14 patients (7.9%). Data collected included patient demographics, type of anesthesia, and specific details of
the surgery such as duration of the operation, distance from the staple line to the dentate line, need for complementary hemostasis,
and any unexpected occurrences. Postoperative data collected included the degree of pain, which was evaluated on the basis
of the type and dosage of analgesics required, laxative consumption, and the presence of bleeding, fever, urinary retention,
or hematomas. Each patient completed a written questionnaire addressing these events. Patients returned for follow-up visits
on days 7, 15, 30, and 90. Responses to pain, bleeding, fever, anal continence, recurrence of hemorrhoids, and level of satisfaction
were compiled. The duration of the procedure ranged from 6 minutes to 2 hours (average 2 3 minutes), and most operations lasted
no more than 20 minutes, with the exception of one that lasted 2 hours because of intraoperative bleeding. Intraoperative
problems were minor. An additional one or a few sutures were required in 58.7% of patients to achieve perfect hemostasis.
In 128 patients (72.3%) the hospital stay was less than 24 hours. Same-day surgery was chosen for 37 patients (20.9%). Pain
was controlled with analgesia only using one to six doses of oral dipirona in 126 patients. Five patients were readmitted
to the hospital: four for control of bleeding and one for conventional hemorrhoidectomy due to an acute episode of external
hemorrhoidal thrombosis. At day 30, patients rated the efficacy of the procedure in alleviating preoperative symptoms as follows:
77.5% excellent; 16% good; 5.3% average, and 1.2% poor. At 3 months postoperatively no patient had had a recurrence of hemorrhoidal
prolapse, and there were no instances of stenosis or anal incontinence. Surgeons also rated the efficacy of the procedure
as excellent in 75%, good in 19.8%, average in 4.7%, and poor in 0.6%. With proper selection of patients and adequate stapling
technique, stapled hemorrhoidectomy may be considered safe; it is easily learned, has a satisfactory degree of pain, and is
well accepted by both patients and surgeons.
Supported in part by Johnson & Johnson. 相似文献
998.
V. Artime J. C. Ramos J. M. Fernandez-Medina M. C. de Luis L. Aguilera 《International orthopaedics》1997,21(1):56-58
Summary. Fracture of components of a total hip arthroplasty occur is a recognised complication. We report an unusual case in which
the fracture occurred through the neck of a femoral component on a Lord type of total hip arthroplasty.
Accepted: 16 March 1996 相似文献
Résumé. Les complications décrites dans la chirurgie prothétique de la hanches sont la rupture des pièces, plus fréquemment de la tige fémorale. Les auteurs rapportent le cas d’une fracture de la tige au niveau du c?ne cervical sur une prothèse de Lord.
Accepted: 16 March 1996 相似文献
999.
1000.