全文获取类型
收费全文 | 760篇 |
免费 | 35篇 |
国内免费 | 19篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 38篇 |
妇产科学 | 11篇 |
基础医学 | 74篇 |
口腔科学 | 13篇 |
临床医学 | 100篇 |
内科学 | 171篇 |
皮肤病学 | 5篇 |
神经病学 | 18篇 |
特种医学 | 152篇 |
外科学 | 87篇 |
综合类 | 12篇 |
预防医学 | 39篇 |
眼科学 | 4篇 |
药学 | 44篇 |
肿瘤学 | 45篇 |
出版年
2021年 | 4篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 8篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 19篇 |
2012年 | 19篇 |
2011年 | 26篇 |
2010年 | 20篇 |
2009年 | 23篇 |
2008年 | 18篇 |
2007年 | 28篇 |
2006年 | 24篇 |
2005年 | 30篇 |
2004年 | 19篇 |
2003年 | 12篇 |
2002年 | 27篇 |
2001年 | 20篇 |
2000年 | 29篇 |
1999年 | 21篇 |
1998年 | 37篇 |
1997年 | 21篇 |
1996年 | 28篇 |
1995年 | 19篇 |
1994年 | 26篇 |
1993年 | 14篇 |
1992年 | 15篇 |
1991年 | 14篇 |
1990年 | 17篇 |
1989年 | 34篇 |
1988年 | 35篇 |
1987年 | 19篇 |
1986年 | 21篇 |
1985年 | 17篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 17篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1971年 | 2篇 |
1970年 | 4篇 |
1969年 | 2篇 |
1964年 | 3篇 |
1947年 | 9篇 |
排序方式: 共有814条查询结果,搜索用时 15 毫秒
61.
S Caserío C Gallego P Martin MT Moral CR Pallás A Galindo 《Acta paediatrica (Oslo, Norway : 1992)》2010,99(10):1571-1577
Aim: To analyse the main prenatal and postnatal features of congenital chylothorax (CC), and the outcome including mid‐term follow‐up. Methods: We searched our databases for CC diagnosed between 1990 and 2006. Data of 29 cases were retrieved and analysed. Follow‐up until 3 years of age was available for all patients. Results: Most patients were diagnosed prenatally (94%) and most cases were complicated by foetal hydrops (66.7%). The overall survival rate at 3 years was 56%. A significantly poorer outcome was observed when foetal hydrops, preterm birth < 34 weeks, large effusions and/or early‐onset pneumothorax were present. An important but not significant improvement in the survival rate was observed through the study period; while in 1990–1998, the survival rate was 41.7%, from 1999 to 2006 it was 66.7% (p = 0.19). In the mid‐term follow‐up, we did not observe any recurrence of CC and most infants remain asymptomatic. However, 27% of survivors were diagnosed as having asthma in early infancy. Conclusion: CC still carries a significant risk of perinatal mortality. However, continuous advances in foetal and neonatal medicine are improving the prognosis of these patients, and nowadays most of them are likely to survive. Beyond the neonatal period, most survivors have an uneventful outcome. 相似文献
62.
Alexandre T Rotta Mário Eduardo G Viana Budi Wiryawan Guilherme A Sargentelli Mark S Dowhy Walter A Zin Bradley P Fuhrman 《Pediatric critical care medicine》2006,7(6):562-570
OBJECTIVE: To evaluate the independent and combined effects of high-frequency oscillatory ventilation (HFOV) and partial liquid ventilation (PLV) on gas exchange, pulmonary histopathology, inflammation, and oxidative tissue damage in an animal model of acute lung injury. DESIGN: Prospective, randomized animal study. SETTING: Research laboratory of a health sciences university. SUBJECTS: Fifty New Zealand White rabbits. INTERVENTIONS: Juvenile rabbits injured by lipopolysaccharide infusion and saline lung lavage were assigned to conventional ventilation (CMV), PLV, HFOV, or high-frequency partial liquid ventilation (HF-PLV) with a full or half dose (HF-PLV1/2) of perfluorochemical (PFC). Uninjured ventilated animals served as controls. Arterial blood gases were obtained every 30 mins during the 4-hr study. Histopathologic evaluation was performed using a lung injury scoring system. Oxidative lung injury was assessed by measuring malondialdehyde and 4-hydroxynonenal in lung homogenates. MEASUREMENTS AND MAIN RESULTS: HFOV, PLV, or a combination of both methods (HF-PLV) resulted in significantly improved oxygenation, more favorable lung histopathology, reduced neutrophil infiltration, and attenuated oxidative damage compared with CMV. HF-PLV with a full PFC dose did not provide any additional benefit compared with HFOV alone. HF-PLV1/2 was associated with decreased pulmonary leukostasis compared with HF-PLV. CONCLUSIONS: The combination of HFOV and PLV (HF-PLV) does not provide any additional benefit compared with HFOV or PLV alone in a combined model of lung injury when lung recruitment and volume optimization can be achieved. The use of a lower PFC dose (HF-PLV1/2) is associated with decreased pulmonary leukostasis compared with HF-PLV and deserves further study. 相似文献
63.
64.
Strangulation in child abuse: CT diagnosis 总被引:2,自引:0,他引:2
The central nervous system is commonly affected in child abuse. Between April 1985 and July 1986 three infants were identified in whom the primary mode of injury had been strangulation. In each case computed tomography (CT) demonstrated a large cerebral infarction confined to vascular territories associated with small subdural hematomas. There was no history or visible evidence of significant head trauma. Autopsy of one infant confirmed the presence of a hemispheric infarct, thin subdural hematoma, and an area of subintimal hemorrhage in the carotid artery ipsilateral to the infarct. The remaining two patients survived with residual hemiparesis. CT findings of a large cerebral infarction with an associated subdural hematoma in an infant without a history of a significant trauma should suggest the possibility of child abuse and may be the primary manifestation of abuse in some patients. 相似文献
65.
A retrospective study was performed to estimate the frequency of alloimmunization against red cell (RBC) antigens in a multiply transfused group. Patients (n = 186) were studied who had received at least six blood transfusions during a period of at least 3 months. Some 6944 units of blood were transfused. One hundred forty patients had hematologic disorders. The patients' sera were investigated every 3 months with indirect antiglobulin tests and enzyme-treated RBCs. Twenty-two patients (11.8%) made 33 antibodies. Seven patients made more than one antibody. Eight of the 22 patients (36.4%) made their first antibody before or at the 10th transfusion. The risk of immunization increased with the number of transfusions. Influence of gender and age was not demonstrable. Nor was a relationship demonstrated between blood transfusion reactions and RBC antibody formation; no delayed hemolytic transfusion reactions occurred. Anti-E was demonstrated in 12 patients and anti-K in 15. When the gene frequencies were taken into account, it appeared that anti-E was made by 11.5 percent of E-negative patients, most of whom were immunized after an estimated three transfusions with E-positive blood. Anti-K was made by 8.7 percent of the K-negative patients, after an estimated 2.1 units of K-positive blood. It might be desirable to match red cell units for the E and K antigens in patients at relatively high risk. These are primarily patients who have already formed an antibody and are going to receive many transfusions and women of childbearing age who are to receive more than 4 units of blood. 相似文献
66.
67.
The NADPH-dependent reduction of chromium (VI), a known carcinogen, by
hepatic microsomes was very similar for all five humans examined, with an
apparent Km for chromate of 1.04-1.68 microM, and a Vmax of 10.4- 10.7
nmol/min/mg protein. Inhibitor studies indicate no role for cytochrome
P450s, but a prominent role for flavoproteins, which could include P450
reductase, flavin-containing mono-oxygenase and cytochrome b5. Relative to
anaerobic conditions, Cr(VI) reduction was inhibited only 26-37% by room
air, which indicates that human microsomal Cr(VI) reduction could still
proceed at significant rates, even in tissues with high O2 tensions.
Studies with lung microsomes from one human exhibited Vmax and Km values
that were two-thirds lower and 2.8-fold greater, respectively, than those
of hepatic microsomes from the same individual; other Cr(VI)-reducing
parameters were similar for lung and liver. Various forms of exogenous
iron, when present at 0.76-6.3 microM, markedly enhanced both liver and
lung microsomal rates and Vmax of Cr(VI) reduction, but did not
significantly alter the other Cr(VI)- reducing parameters (Km, effects of
O2 and inhibitors). These iron levels were 3.1- to 26-fold lower than the
initial Cr(VI) concentration, which suggests that iron is serving a
catalytic role. The ratio of human microsomal Cr(VI) reduction rates under
aerobic versus anaerobic conditions remained fairly constant, regardless of
iron concentration. Small increases in intracellular iron could therefore
lead to large increases in the rate and extent of microsomal Cr(VI)
reduction. Individuals that are simultaneously exposed to Cr(VI) and to
agents that increase intracellular iron could therefore be at potentially
greater risk for Cr(VI) toxicity and carcinogenicity.
相似文献
68.
S E Curtis B P Fuhrman D F Howland M DeFrancisis E K Motoyama 《Critical care medicine》1991,19(2):225-230
BACKGROUND AND METHODS: Liquid ventilation using perfluorocarbons is a new technique for ventilation of infants with restrictive lung disease. However, this method of ventilation has been shown to impair cardiac output (Qt) in several animal species, casting doubt as to its feasibility. This study tested whether Qt could be maintained during liquid breathing by intravascular volume expansion. Seven piglets were carefully hydrated, instrumented for continuous Qt measurement, and subjected to 2 hr of liquid breathing. PaCO2 was maintained at 40 to 50 torr (5.3 to 6.7 kPa), and PaO2 greater than 80 torr (greater than 10.7 kPa). Additional colloid was given during liquid breathing if Qt decreased to less than 90% of preliquid breathing values. RESULTS: Four piglets maintained Qt throughout the liquid breathing trial with maintenance fluids only. Three piglets each required one 10 mL/kg fluid bolus for Qt 82% to 89% of the baseline value, after which Qt rapidly increased to greater than 90% of baseline. Oxygen consumption and serum lactate levels remained normal throughout liquid breathing. CONCLUSION: Qt is readily maintained during liquid breathing in properly hydrated animals. 相似文献
69.
70.
Moore AD; Godwin JD; Muller NL; Naidich DP; Hammar SP; Buschman DL; Takasugi JE; de Carvalho CR 《Radiology》1989,172(1):249-254
The authors retrospectively evaluated radiographs, computed tomographic (CT) scans, and results of pulmonary function tests (when available) for 17 patients with biopsy-proved pulmonary histiocytosis X. In 11 patients, high-resolution CT was used. In 12 patients, CT demonstrated cystic air spaces, usually less than 10 mm in diameter. In three of these 12, cysts were the only abnormality, but in six others, nodules (usually less than 5 mm in diameter) were also present. Two patients had only nodules and one, only emphysema. CT showed that many lesions that appeared reticular on plain radiographs were actually cysts. CT showed no central or peripheral concentration of lesions, but it did reveal that many small nodules were distributed in the centers of secondary lobules around small airways. CT findings correlated better with the diffusing capacity (rho = -0.71) than did the plain radiographic findings (rho = -0.57). Thus, CT was better than radiography at showing the morphology and distribution of lung abnormalities. 相似文献