全文获取类型
收费全文 | 22571篇 |
免费 | 1645篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 225篇 |
儿科学 | 898篇 |
妇产科学 | 587篇 |
基础医学 | 3044篇 |
口腔科学 | 653篇 |
临床医学 | 2563篇 |
内科学 | 4369篇 |
皮肤病学 | 312篇 |
神经病学 | 1809篇 |
特种医学 | 953篇 |
外科学 | 3075篇 |
综合类 | 378篇 |
一般理论 | 43篇 |
预防医学 | 2132篇 |
眼科学 | 342篇 |
药学 | 1400篇 |
1篇 | |
中国医学 | 16篇 |
肿瘤学 | 1456篇 |
出版年
2022年 | 142篇 |
2021年 | 329篇 |
2020年 | 229篇 |
2019年 | 367篇 |
2018年 | 396篇 |
2017年 | 327篇 |
2016年 | 332篇 |
2015年 | 417篇 |
2014年 | 575篇 |
2013年 | 761篇 |
2012年 | 1112篇 |
2011年 | 1205篇 |
2010年 | 648篇 |
2009年 | 552篇 |
2008年 | 1075篇 |
2007年 | 1172篇 |
2006年 | 1092篇 |
2005年 | 1079篇 |
2004年 | 949篇 |
2003年 | 940篇 |
2002年 | 809篇 |
2001年 | 637篇 |
2000年 | 627篇 |
1999年 | 519篇 |
1998年 | 249篇 |
1997年 | 214篇 |
1996年 | 220篇 |
1995年 | 219篇 |
1994年 | 203篇 |
1993年 | 184篇 |
1992年 | 469篇 |
1991年 | 455篇 |
1990年 | 438篇 |
1989年 | 441篇 |
1988年 | 404篇 |
1987年 | 362篇 |
1986年 | 313篇 |
1985年 | 387篇 |
1984年 | 290篇 |
1983年 | 266篇 |
1982年 | 169篇 |
1979年 | 215篇 |
1978年 | 188篇 |
1977年 | 154篇 |
1976年 | 148篇 |
1975年 | 160篇 |
1974年 | 158篇 |
1973年 | 197篇 |
1972年 | 159篇 |
1971年 | 142篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
S Likitnukul G H McCracken J D Nelson T P Votteler 《American journal of diseases of children (1960)》1987,141(1):41-44
We identified 35 patients who had epididymitis from 1965 to 1984 by hospital chart review. The common clinical presentation was swelling, pain, and erythema. Twenty-two patients had onset of symptoms within 24 hours of hospital admission. Surgery was performed in 31 patients, 22 of whom had cultures taken from the epididymis at the time of surgery. Bacterial agents were recovered from cultures of 13 patients: coagulase-negative staphylococci were identified in nine patients. In two patients, a polymicrobic cause was found. Six patients had associated urologic abnormality. Three patients had concurrent urinary tract infection. Urologic investigation should be undertaken in children younger than 2 years old and in older patients with recurrent episodes suspected to be due to reflux of urine and associated genitourinary abnormality. 相似文献
992.
Epidemiologic markers of pediatric infections caused by coagulase-negative staphylococci 总被引:12,自引:0,他引:12
Several epidemiologic markers (species, slime production and antimicrobial susceptibility) were examined for 256 isolates of coagulase-negative staphylococci (C-S) obtained from clinical specimens in a 1-year period. The medical records of the 169 pediatric patients from whom the C-S were obtained were reviewed and divided into infected (N = 11) and uninfected (N = 158) groups. The phenotypic traits of strains associated with infection included: (1) slime production (P = 0.014); (2) slime-positive Staphylococcus epidermidis (P = 0.002); and (3) resistance to penicillin (P = 0.03), oxacillin (P less than 0.001), clindamycin (P = 0.003), chloramphenicol (P less than 0.001) and trimethoprim/sulfamethoxazole (P less than 0.001). Infected patients were significantly older (P = 0.006) than uninfected patients. Simultaneous isolation of the same strain of C-S from the aerobic and anaerobic bottles of a single blood culture increased the probability of sepsis (P = 0.004). The combination of these patient and laboratory data may be useful in determining the clinical significance of C-S recovered from pediatric patients. 相似文献
993.
S J Fomon D E Matthews D M Bier R R Rogers C J Rebouche B B Edwards S E Nelson 《The Journal of pediatrics》1987,111(2):221-224
Because the human body has no enzymes capable of hydrolyzing urea, nitrogen from this source becomes bioavailable only by release of ammonia from urea by bacterial hydrolysis in the intestines, with subsequent absorption and utilization of ammonia. To explore extent to which urea ingested in milk becomes bioavailable, we fed di-15N-urea (both nitrogen atoms in the form of the stable isotope 15N) and determined urinary excretion of di-15N-urea (excreted without having become bioavailable) and mono-15N-urea (urea containing only one atom of 15N and therefore reflecting excretion of absorbed ammonia). The largest percentage of the ingested di-15N-urea was excreted promptly in the urine still in the form of di-15N-urea. We conclude that most of the urea ingested by a normal infant is not bioavailable. 相似文献
994.
S A Saad H E Fadel K Fahmy G H Nelson M Moustafa H C Davis 《American journal of obstetrics and gynecology》1987,157(6):1516-1520
Lecithin phosphorus concentration, the standard fetal lung maturity test in our institution, and phosphatidylglyercol were assayed in 69, 29, and 45 amniotic fluid samples from normal (GI), gestational (GII), and insulin-dependent diabetic (GIII) women by means of thin layer chromatography and Amniostat-FLM, respectively. Lecithin phosphorus concentration greater than or equal to 0.1 mg/dl and positive or strong positive Amniostat-FLM results were considered mature. The results of both assays were concordant in 79% of the samples. The discordance rate was highest in GIII patients. In our experience, respiratory distress syndrome did not develop in neonate infants of diabetic women delivered after a mature lecithin result. With lecithin phosphorus concentration as the reference standard, the predictive value of a mature Amniostat-FLM result was 96.2%, whereas that of an immature result was 58.5%. Respiratory distress syndrome occurred in only two GIII neonates who were delivered within 72 hours of both immature lecithin and Amniostat-FLM results. These findings support the use of Aminostat-FLM as a screening test for fetal lung maturity in both normal and diabetic pregnancies. Additional tests will be necessary to evaluate further fetal lung maturity only if the results are negative. 相似文献
995.
Birth weight-specific fetal death rates were evaluated for Alabama for the years 1974-1983. The fetal death rate for the total low birth weight group improved less than 20% during the decade, whereas the fetal death rate for the 2500-3999-g birth weight group improved 40%, and the fetal death rate for the group of 4000 g or more improved 71%. By 1983, 76% of all stillbirths weighed less than 2500 g, compared with 66% in 1974. In contrast, in both years, only about 7% of live births weighed less than 2500 g. This study suggests that increased reporting of stillbirths of less than 500 g has contributed to the recent apparent lack of improvement in stillbirth rates in Alabama. 相似文献
996.
We estimated the size of the thyroid gland by palpation and measured thyroid gland volume with ultrasound in the immediate postpartum period and six months after delivery in 16 women. The 13% reduction in the mean thyroid gland volume detected six months after delivery implied that the thyroid gland enlarges slightly during pregnancy. Physical examination, however, did not detect any goiters during the immediate postpartum period and did not identify a change in thyroid gland size six months after delivery. The thyroid gland enlargement that occurs during pregnancy is not large enough to be detected by physical examination. We urge physicians to discard the commonly held notion that goiter frequently develops during pregnancy. 相似文献
997.
R L Goldenberg J F Huddleston K G Nelson 《American journal of obstetrics and gynecology》1984,149(6):651-654
One- and five-minute Apgar scores and umbilical cord arterial pH values were compared in preterm newborn infants of various gestational ages. The more premature the infant, the more likely the Apgar score was low in the presence of a pH greater than or equal to 7.25. Conversely, the closer to term, the more frequently an infant with a pH of less than 7.25 had an Apgar score of greater than or equal to 7. Therefore, in preterm infants, there is little congruity between the Apgar score and umbilical cord pH. Based on these findings, it is not appropriate to label preterm newborn infants as asphyxiated based on a low Apgar score. 相似文献
998.
Passive intestinal permeability in 33 newborn babies was studied using feeds containing lactulose and mannitol. Each marker is thought to pass across the gut wall by a different route; lactulose by a paracellular and mannitol by a transcellular pathway. Neither is metabolised and both are wholly and solely excreted by the kidney; urinary recovery is a measure of the intestinal uptake. Babies born before 34 weeks' gestation exhibited a higher intestinal permeability to lactulose than more mature babies, and all preterm babies showed an appreciable decline in lactulose absorption during the first week of oral feeds. Babies of 34 to 37 weeks' gestation achieved a 'mature' intestinal permeability to lactulose within four days of starting oral feeds. These findings may reflect the immaturity of the gut of the preterm baby rather than a process essential to adaptation to enteral nutrition. 相似文献
999.
1000.
Prognostic significance of hypernatremia and hyponatremia among patients with aneurysmal subarachnoid hemorrhage 总被引:4,自引:0,他引:4
Qureshi AI Suri MF Sung GY Straw RN Yahia AM Saad M Guterman LR Hopkins LN 《Neurosurgery》2002,50(4):749-55; discussion 755-6
OBJECTIVE: Abnormal serum sodium levels (hyponatremia and hypernatremia) are frequently observed during the acute period after aneurysmal subarachnoid hemorrhage (SAH) and may worsen cerebral edema and mass effect. We performed this study to determine the prognostic significance of serum sodium concentration abnormalities. METHODS: We analyzed prospectively collected data for the placebo treatment group in a clinical trial conducted at 54 neurosurgical centers in North America. The presence of hypernatremia (serum sodium concentration of >145 mmol/L) and hyponatremia (serum sodium concentration of <135 mmol/L) was determined with serum sodium measurements obtained at admission and 3, 6, and 9 days after SAH. The effects of hypernatremia and hyponatremia on the risk of symptomatic vasospasm and on 3-month outcomes were analyzed after adjustment for the following potential confounding factors: age, sex, preexisting hypertension, admission Glasgow Coma Scale score, initial mean arterial pressure, subarachnoid clot thickness, intraventricular blood or intraparenchymal hematoma, ventricular dilation, and aneurysm size and location. RESULTS: Of 298 patients in the analysis, 58 (19%) developed hypernatremia and 88 (30%) developed hyponatremia. Hypernatremia was significantly associated with poor outcomes (odds ratio, 2.7; 95% confidence interval, 1.2-6.1). A positive correlation was observed between the highest sodium values recorded and Glasgow Outcome Scale scores at 3 months (P < 0.0001 by analysis of variance). Hyponatremia was not associated with 3-month outcomes (odds ratio, 1.9; 95% confidence interval, 0.9-4.3). Neither hypernatremia nor hyponatremia was associated with the risk of symptomatic vasospasm. CONCLUSION: Hyponatremia seems to be more common than hypernatremia after SAH. However, hypernatremia after SAH is independently associated with poor outcomes, and this association is independent of previously identified outcome predictors, including age and admission Glasgow Coma Scale scores. Further studies are needed to define the underlying mechanism of this association. 相似文献