全文获取类型
收费全文 | 22431篇 |
免费 | 2150篇 |
国内免费 | 89篇 |
专业分类
耳鼻咽喉 | 195篇 |
儿科学 | 878篇 |
妇产科学 | 512篇 |
基础医学 | 2896篇 |
口腔科学 | 485篇 |
临床医学 | 2536篇 |
内科学 | 4618篇 |
皮肤病学 | 176篇 |
神经病学 | 2128篇 |
特种医学 | 871篇 |
外科学 | 3121篇 |
综合类 | 395篇 |
一般理论 | 12篇 |
预防医学 | 2420篇 |
眼科学 | 461篇 |
药学 | 1556篇 |
1篇 | |
中国医学 | 26篇 |
肿瘤学 | 1383篇 |
出版年
2021年 | 344篇 |
2020年 | 203篇 |
2019年 | 398篇 |
2018年 | 399篇 |
2017年 | 268篇 |
2016年 | 329篇 |
2015年 | 355篇 |
2014年 | 595篇 |
2013年 | 893篇 |
2012年 | 1214篇 |
2011年 | 1233篇 |
2010年 | 694篇 |
2009年 | 620篇 |
2008年 | 1131篇 |
2007年 | 1258篇 |
2006年 | 1154篇 |
2005年 | 1122篇 |
2004年 | 1091篇 |
2003年 | 1070篇 |
2002年 | 1067篇 |
2001年 | 489篇 |
2000年 | 513篇 |
1999年 | 459篇 |
1998年 | 307篇 |
1997年 | 272篇 |
1996年 | 285篇 |
1995年 | 272篇 |
1994年 | 250篇 |
1993年 | 234篇 |
1992年 | 364篇 |
1991年 | 314篇 |
1990年 | 338篇 |
1989年 | 348篇 |
1988年 | 298篇 |
1987年 | 301篇 |
1986年 | 321篇 |
1985年 | 290篇 |
1984年 | 255篇 |
1983年 | 243篇 |
1982年 | 192篇 |
1981年 | 201篇 |
1980年 | 159篇 |
1979年 | 216篇 |
1978年 | 185篇 |
1977年 | 132篇 |
1976年 | 149篇 |
1975年 | 144篇 |
1974年 | 148篇 |
1973年 | 146篇 |
1972年 | 126篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
991.
Sleeping position and sudden infant death syndrome (SIDS): effect of an intervention programme to avoid prone sleeping 总被引:4,自引:0,他引:4
T Markestad B Skadberg E Hordvik I Morild LM Irgens 《Acta paediatrica (Oslo, Norway : 1992)》1995,84(4):375-378
The proportion of prone sleeping among sudden infant death syndrome (SIDS) victims and infants in general, and the rate of SIDS were prospectively studied in the county of Hordaland, Norway, three years before (1987–89) and three years after (1990–92) a campaign to discourage prone sleeping. Before the campaign, 64% of random reference infants were put prone versus 8% after (p < 0.0001). Concurrently, the rate of SIDS decreased from 3.5 to 1.6 per 1000 live births (63 infants before and 30 after the campaign, p = 0.0002). Prone sleeping was not considered a statistically significant risk factor for SIDS before (OR 2.0,95% CI 0.8–4.5), but was highly significant (OR 11.3,95% CI 3.6–36.5) after the campaign. Prone sleeping is an important risk factor for SIDS, but the association may be missed in epidemiological studies if prone is the predominant sleeping position. Behaviour with regard to sleeping position may be changed rapidly by means of a simple campaign. 相似文献
992.
Yu Jing; Russell M.; Salomon N.; Murphy James C.; Palley Lori S.; Fox James G. 《Carcinogenesis》1995,16(8):1927-1931
The effect of Helicobacter mustelae infection on gastric epithelialproliferation was studied in ferrets colonized with H.mustelaeand specific pathogen-free (SPF) ferrets not infected with H.mustelae.Thirteen H.mustelae-infected ferrets between the ages of 13and 32 months and 16 SPF ferrets between 6 and 18 months wereanalyzed. Bacterial cultures, urease tests and Warthin-Starrystains were used to identify H.mustelae. Tissues obtained fromthe antrum and the body regions of the stomach were assayedby proliferating cell nuclear antigen (PCNA) immunohisto-chemistryand measured using a computerized color image analysis system.PCNA-expressing gastric epithelia in the antrum and the bodyregions were significantly increased in the H.mustelae-infectedferrets versus the SPF ferrets (P <0.001). PCNA positivityin the antrum regions of both the H.mustelae-infected ferretsand SPF ferrets was significantly higher than that of the bodyregions (P <0.001). Comparison of the histopathology of infectedferrets indicated that PCNA positivity correlated with the histologicalseverity of gastritis. This study suggests that cell proliferationin ferret gastric mucosa increases with H.mustelae infectionand provides evidence that PCNA is a useful biomarker for studyingthe changes in cell kinetics in the ferret stomach. The dataalso further support the use of the H.mustelae-infected ferretas an animal model for studying the pathogenesis of Helicobacterpylori-induced gastric diseases of humans. 相似文献
993.
Halperin SA Smith B Russell M Hasselback P Guasparini R Skowronski D Meekison W Parker R Lavigne P Barreto L 《Vaccine》2000,18(14):1312-1319
Pertussis is increasingly being recognized as an important cause of cough illness in adolescents and adults. To evaluate the safety and immunogenicity of an adult formulation of a five-component (pertussis toxoid, filamentous hemagglutinin, pertactin, fimbriae 2 and 3) acellular pertussis vaccine combined with diphtheria and tetanus toxoids, we randomly allocated 749 healthy adolescents and adults from 12-54 years of age recruited from five Canadian communities to receive either tetanus-diphtheria vaccine (Td), acellular pertussis vaccine (aP) or combined diphtheria-tetanus-acellular pertussis vaccine (TdaP). Subjects and personnel were unaware of the vaccine allocation. Antibody levels were measured before and one month postimmunization; adverse events were collected at 24 and 72 h and 8 to 10 days. Adverse events were reported in similar frequency amongst the three vaccine groups. Moderate pain at the injection site was reported less frequently in the aP group than the TdaP group (10.7% compared to 19.4%; relative risk 0.6, 95% confidence interval 0.3-0.9). Chills were reported less frequently after Td (5.3%) than after TdaP (12.5%; relative risk 0.4, 95% confidence interval 0.2-0.9). There were no statistically significant differences between recipients of Td and TdaP in tetanus and diphtheria antitoxin levels achieved. Antibody response against Bordetella pertussis antigens was vigorous in all groups although recipients of aP alone had higher levels of antibody levels against pertussis toxoid, fimbriae, and agglutinins and lower antibody levels against pertactin than did TdaP recipients. We conclude that this adult formulation 5-component acellular pertussis vaccine is safe and immunogenic in adolescents and adults and is a candidate vaccine for adolescent and adult immunization programs. 相似文献
994.
995.
OBJECTIVE: The trial evaluated the effectiveness of the investigational antihistaminic and antiallergic compound Azelastine Eye Drops (AZE) in the treatment of allergic conjunctivitis using an allergen challenge model. DESIGN: Randomized, double-blind, placebo-controlled, paired-eye study. PARTICIPANTS: Adults with a history of allergic conjunctivitis (>/=2 years) who were asymptomatic throughout the trial, had a positive skin test (cat dander, grass, or ragweed pollen within the last year), and had a positive conjunctival reaction (score 2+ or more for itching and redness in both eyes on a 0-4 scale) during two separate conjunctival provocation tests (CPT) before randomization. METHODS: Eighty patients underwent a 2-week screening period (visits 1 and 2) that included a CPT during visit 1 to establish the allergen threshold dose and a second confirmatory CPT performed at visit 2. Eye symptom assessments for itching (evaluated by patient) and conjunctival redness (evaluated by physician) were performed 5 and 10 minutes after CPT using a 5-point scale (from 0 = none to 4+ = severe). Qualified patients were randomized to receive one drop of AZE (0.015 mg of azelastine hydrochloride) in one eye and one drop of placebo in the other eye 20 minutes before CPT at visit 3 (onset) and 8 or 10 hours before CPT at visit 4 (duration). MAIN OUTCOME MEASURES: Individual severity scores for itching (evaluated by patient) and conjunctival redness (evaluated by physician) for each eye at 3, 5, and 10 minutes after CPT at visits 3 and 4 using a 5-point scale (0 = none to 4+ = very severe). RESULTS: Each of the 80 randomized patients completed the trial. Mean itching and conjunctival redness scores at visit 3 (onset) were significantly lower (P: < 0.001) in the AZE-treated eyes than in the placebo-treated eyes. At visit 4 (duration), mean itching and conjunctival redness scores (P: = 0.003) for the 8-hour group and mean itching scores (P: = 0.001) for the 10-hour group were significantly lower in the AZE-treated eyes than in the placebo-treated eyes. Significant differences in mean tearing and chemosis severity scores were also seen at visit 3 (onset) and visit 4 (duration) in the AZE-treated eyes when compared with the placebo-treated eyes. Treatment with AZE was well tolerated. CONCLUSIONS: Therapy of experimentally induced allergic conjunctivitis with AZE was highly effective, with an onset of action seen within 3 minutes and a duration of effect of at least 8 to 10 hours. 相似文献
996.
C Costalos G Russell Q Al Rahim M J Tarlow D J Lloyd K R Ross 《Acta paediatrica Scandinavica》1985,74(3):382-385
Serial plasma glucose estimations were performed in 44 light-for-date infants and 17 infants of diabetic mothers fed 2, 3 or 4-hourly with feeds containing 10% additional carbohydrate in the form of a glucose polymer (Caloreen). In the infants fed 2 and 3-hourly, plasma glucose was higher following the high carbohydrate feeds, particularly immediately before the next feed was due. Given 4-hourly, the high carbohydrate feed had little effect in most light-for-date infants, and in one light-for-date infant and two infants of diabetic mothers the plasma glucose was lower at the end of 4 hours than following normal formula. It is concluded that the addition of glucose polymer to feeds given 2 and 3 hourly has a potentially useful effect in neonates at risk of developing hypoglycaemia, but it cannot be used to increase the feed interval to 4 hours. 相似文献
997.
P Russell P M Bannatyne H J Solomon L D Stoddard M H Tattersall 《International journal of gynecological pathology》1985,4(3):192-210
A review of 128 cases of "primary" ovarian müllerian carcinoma treated at the King George V Memorial Hospital was undertaken to determine the relative frequency with which such tumors were associated with evidence of multifocal primary neoplasia. Of the 128 cases studied, 115 were invasive carcinomas and 13 were noninvasive or borderline ovarian tumors ("tumors of low malignant potential"). Eight of 10 borderline serous ovarian tumors (80%) and 37 of 75 invasive serous carcinomas (49%) exhibited evidence of independent primary neoplasia at more than one anatomical site in the biopsy material available for review. Many of these cases represented bilateral primary ovarian tumors, but autochthonous extraovarian neoplasia was also commonly encountered. A single borderline endometrioid ovarian tumor and six of 15 endometrioid carcinomas (40%) were associated with biopsy-proven multifocal primary tumorigenesis. These were predominantly neoplasms in one or both ovaries plus adenocarcinoma in the uterine corpus. Other histological types of malignant common epithelial tumors of the ovaries did not demonstrate any such tendency, highlighting major differences in pathogenesis between members of this loosely associated group of ovarian cancers. Our study suggests that gynecological endometrioid and serous malignancies are commonly multifocal and we feel this has significant implications for the way these neoplasms are staged and therefore treated. 相似文献
998.
Of the 103 patients taken to the operating room for hysteroscopic resection of a septum, 72 underwent successful resection of the septum. The initial hysterogram can identify those patients who may benefit from the procedure but cannot discriminate between bicornuate and septate uteri. Knowledge of the size and contour of the uterus is essential to the final decision to proceed transcervically, opposed to transabdominally. In the transcervical repair group, at the time this article was written, there were 58 term deliveries and 5 ongoing pregnancies greater than 30 weeks (1 had a spontaneous abortion after surgery and subsequently conceived a term pregnancy), for a successful pregnancy rate of 86%. This correlated well with the pregnancy rates observed after metroplasty. Therefore, hysteroscopic resection constitutes a valuable alternative to the classical transabdominal approach. 相似文献
999.
A controlled prospective study to evaluate the efficacy of expired ipecac syrup was conducted at two regional poison control centers in New England. During a 6-month period, 200 study patients treated with expired ipecac syrup and 200 control patients treated with unexpired ipecac syrup were evaluated. There were no statistical differences between the control and study groups in patient characteristics (age and sex) and product characteristics (general class, emetic potential, pretreatment, previously opened bottles, and manufacturer). In both control and study groups, emesis occurred in 100% of cases with 90% of patients vomiting with the first dose. The mean time to emesis was 24.7 minutes and 24.8 minutes in the study and control groups, respectively. Expired preparations ranged from 1 month to greater than 4 years postexpiration, with the duration of expiration not altering the mean time to emesis. Mean time to emesis between the two groups was also not affected by manufacturer, pretreatment with milk, or whether the ipecac syrup bottle was previously opened. We conclude that expired ipecac syrup (up to 4 years postexpiration date) is an effective emetic. 相似文献
1000.
Growth and differentiation of fetal rat intestine transplants: dependence on insulin and growth hormone 总被引:1,自引:0,他引:1
We have studied the role of hormones in the growth and differentiation of fetal rat intestine. Pieces of small intestine from 15-day fetal rats were transplanted under the renal capsule of either normal, hypophysectomized (HX), or diabetic adult rats and grown for 11 days. Intestine transplants in control hosts showed normal differentiation and they increased 60-fold in protein content and wet weight. Growth of transplants in HX and diabetic hosts was reduced by 50 and 25%, respectively. Transplants in diabetic hosts were histologically normal, while those in HX hosts failed to develop villi and discrete smooth muscle layers. Normal growth and differentiation in HX and diabetic hosts were completely restored by administration of growth hormone (GH) or insulin, respectively. Our data indicate that both GH and insulin are necessary for normal growth of the transplanted intestine during a period corresponding to late fetal and early neonatal life, but only the former is required for normal differentiation. 相似文献