全文获取类型
收费全文 | 20365篇 |
免费 | 1314篇 |
国内免费 | 72篇 |
专业分类
耳鼻咽喉 | 180篇 |
儿科学 | 442篇 |
妇产科学 | 479篇 |
基础医学 | 2973篇 |
口腔科学 | 727篇 |
临床医学 | 2431篇 |
内科学 | 4171篇 |
皮肤病学 | 403篇 |
神经病学 | 2007篇 |
特种医学 | 536篇 |
外科学 | 2146篇 |
综合类 | 212篇 |
一般理论 | 11篇 |
预防医学 | 1935篇 |
眼科学 | 277篇 |
药学 | 1555篇 |
中国医学 | 105篇 |
肿瘤学 | 1161篇 |
出版年
2023年 | 194篇 |
2022年 | 282篇 |
2021年 | 555篇 |
2020年 | 333篇 |
2019年 | 591篇 |
2018年 | 783篇 |
2017年 | 540篇 |
2016年 | 599篇 |
2015年 | 751篇 |
2014年 | 867篇 |
2013年 | 1184篇 |
2012年 | 1722篇 |
2011年 | 1730篇 |
2010年 | 850篇 |
2009年 | 711篇 |
2008年 | 1282篇 |
2007年 | 1258篇 |
2006年 | 1201篇 |
2005年 | 1120篇 |
2004年 | 1071篇 |
2003年 | 957篇 |
2002年 | 881篇 |
2001年 | 168篇 |
2000年 | 147篇 |
1999年 | 151篇 |
1998年 | 114篇 |
1997年 | 102篇 |
1996年 | 112篇 |
1995年 | 64篇 |
1994年 | 55篇 |
1993年 | 54篇 |
1992年 | 80篇 |
1991年 | 68篇 |
1990年 | 80篇 |
1989年 | 78篇 |
1988年 | 64篇 |
1987年 | 62篇 |
1986年 | 68篇 |
1985年 | 60篇 |
1984年 | 76篇 |
1983年 | 49篇 |
1982年 | 66篇 |
1981年 | 57篇 |
1980年 | 51篇 |
1979年 | 36篇 |
1977年 | 29篇 |
1975年 | 27篇 |
1974年 | 31篇 |
1973年 | 25篇 |
1972年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Luiz A Benvenuti Francisco O S Fran?a Kátia C Barbaro José R Nunes Jo?o L C Cardoso 《Toxicon》2003,42(3):331-334
A 36-year old woman was bitten on the left ankle by a Bothrops jararacussu, and died 45 min after the bite. At necropsy, there were local signs of envenoming with haemorrhage, thrombosis and necrosis of the subcutaneous and muscular tissue. Multiple fibrin and platelet thrombi were found in the microcirculation of the heart and lungs, suggesting the occurrence of disseminated intravascular coagulation. Pulmonary haemorrhage probably secondary to the action of haemorrhagins, consumption coagulopathy and disseminated intravascular coagulation was the immediate cause of death. Intravenous inoculation of the venom could have occurred in the present case, which would explain the rapid onset of coagulation disorders, haemorrhage and death. 相似文献
102.
103.
Dietary carotenoids and risk of lung cancer in a pooled analysis of seven cohort studies. 总被引:5,自引:0,他引:5
Satu M?nnist? Stephanie A Smith-Warner Donna Spiegelman Demetrius Albanes Kristin Anderson Piet A van den Brandt James R Cerhan Graham Colditz Diane Feskanich Jo L Freudenheim Edward Giovannucci R Alexandra Goldbohm Saxon Graham Anthony B Miller Thomas E Rohan Jarmo Virtamo Walter C Willett David J Hunter 《Cancer epidemiology, biomarkers & prevention》2004,13(1):40-48
Intervention trials with supplemental beta-carotene have observed either no effect or a harmful effect on lung cancer risk. Because food composition databases for specific carotenoids have only become available recently, epidemiological evidence relating usual dietary levels of these carotenoids with lung cancer risk is limited. We analyzed the association between lung cancer risk and intakes of specific carotenoids using the primary data from seven cohort studies in North America and Europe. Carotenoid intakes were estimated from dietary questionnaires administered at baseline in each study. We calculated study-specific multivariate relative risks (RRs) and combined these using a random-effects model. The multivariate models included smoking history and other potential risk factors. During follow-up of up to 7-16 years across studies, 3,155 incident lung cancer cases were diagnosed among 399,765 participants. beta-Carotene intake was not associated with lung cancer risk (pooled multivariate RR = 0.98; 95% confidence interval, 0.87-1.11; highest versus lowest quintile). The RRs for alpha-carotene, lutein/zeaxanthin, and lycopene were also close to unity. beta-Cryptoxanthin intake was inversely associated with lung cancer risk (RR = 0.76; 95% confidence interval, 0.67-0.86; highest versus lowest quintile). These results did not change after adjustment for intakes of vitamin C (with or without supplements), folate (with or without supplements), and other carotenoids and multivitamin use. The associations generally were similar among never, past, or current smokers and by histological type. Although smoking is the strongest risk factor for lung cancer, greater intake of foods high in beta-cryptoxanthin, such as citrus fruit, may modestly lower the risk. 相似文献
104.
Effect of a cognitive behavioral intervention on reducing symptom severity during chemotherapy. 总被引:4,自引:0,他引:4
Charles Given Barbara Given Mohammad Rahbar Sangchoon Jeon Ruth McCorkle Bernadine Cimprich Andrzej Galecki Sharon Kozachik Albert Brady Mary Jo Fisher-Malloy Kathy Courtney Elizabeth Bowie 《Journal of clinical oncology》2004,22(3):507-516
PURPOSE: To describe a randomized trial of a cognitive behavioral intervention on reducing symptom severity among patients diagnosed with solid tumors and undergoing a first course of chemotherapy and to determine whether the intervention had an additive or interactive effect on symptom severity in the presence of supportive care medications. PATIENTS AND METHODS: Patients (N = 237) were accrued from comprehensive and community cancer centers, interviewed, and randomly assigned to either the experimental intervention (n = 118) or conventional care (n = 119). A symptom severity index, based on summed severity scores across 15 symptoms, was the primary outcome. Each patient's site of cancer, stage at diagnosis, chemotherapy protocols, and use of supportive medications were learned from medical records. RESULTS: Groups were equivalent at baseline, and attrition by characteristics by group was not different. The proportion of patients not receiving chemotherapy at 10 and 20 weeks did not differ by group. At the 10- and 20-week observations, there was a significant interaction between the experimental group and baseline symptom severity. Patients in the experimental group who entered the trial with higher symptom severity reported significantly lower severity at 10 and 20 weeks. Controlling for chemotherapy treatment status at follow-up and supportive care medications did not alter the effect of the experimental intervention. CONCLUSION: Compared with conventional care alone, the experimental intervention was effective among patients who entered the trial with higher levels of symptom severity. Age, sex, site or stage of cancer, and supportive medications did not modify the effect of this cognitive behavioral intervention on symptom severity. 相似文献
105.
Pulmonary tuberculosis in five young infants with nursery exposure: clinical, radiographic and CT findings 总被引:4,自引:0,他引:4
K.-I. Kim J. W. Lee Jae Hong Park Su Young Kim Hee Ju Park Phil Jo Choi Ki Nam Lee H. J. Kim Suk Hong Lee 《Pediatric radiology》1998,28(11):836-840
Clinical, radiographic (n = 5) and CT findings (n = 4) of five Korean infants ranging in age from 2 to 3 months with confirmed tuberculosis were retrospectively analysed.
All of the patients were symptomatic, anergic to tuberculin, and had a positive culture of Myobacterium tuberculosis in gastric aspirates. The probable source of infection was the hospital in which they were born. CT scans demonstrated hilar
and mediastinal lymph node enlargement with central low attenuation and peripheral enhancement in all cases. CT may be useful
in diagnosis by demonstrating characteristic adenopathy and disseminated disease in young infants.
Received: 2 September 1997 Accepted: 23 April 1998 相似文献
106.
107.
Phospholipase D (PLD) is one of the intracellular signal transduction enzymes and plays an important role in a variety of cellular functions. We investigated the distribution of PLD isozyme, PLD1 in the rat brain and spinal cord using an immunological approach. Western blot analysis showed the presence of PLD1 protein in all tissues studied, with significantly higher levels in the brainstem and spinal cord, which was correlated with the results obtained from PLD activity assay. Prominent and specific signals of PLD1 were observed in many functionally diverse brain areas, including the olfactory bulb, medial septum-diagonal band complex, cerebral cortex, brainstem, cerebellum, and spinal cord. In the brainstem, the red nucleus, substantia nigra, interpeduncular nucleus, cranial motor nuclei (trigeminal motor, abducent, facial, and hypoglossal), sensory cranial nerve nuclei (spinal trigeminal, vestibular, and cochlear), as well as nuclei of the reticular formation, all showed intense immunoreactivity. Purkinje cells and deep cerebellar nuclei of the cerebellum were also labeled intensely. However, no significant labeling was found in the thalamus, epithalamus, and basal ganglia. Although many of the PLD1 immunoreactive cells were neurons, PLD1 was also expressed in glial cells such as presumed astrocytes and tanycytes. These findings suggest that PLD1 may play an important role in the central nervous system of the adult rat. 相似文献
108.
We investigated the use of measurements of serum concentrations of the cardiac proteins troponins I and T as biochemical markers of myocardial cell damage in 80 patients undergoing vascular or major orthopaedic surgery. Holter electrocardiographic monitoring was carried out before surgery and for 3 days after surgery. Blood samples for troponins I and T and creatine kinase-MB isoenzyme were taken on each of these 4 days. Outcome was assessed at 3 months using a patient questionnaire, general practitioner follow-up and case notes review. Silent postoperative myocardial ischaemia was detected in 21 patients; increases in troponins I and T and creatine kinase-MB occurred in four, six and 17 of these patients, respectively. Eight patients suffered major postoperative complications (cardiac death, myocardial ischaemia, congestive cardiac failure, unstable angina and cerebrovascular accident) and 21 minor complications (poorly controlled hypertension needing increased or new additional treatment, palpitations, increased tiredness or shortness of breath in the absence of known respiratory disease). There were no associations between postoperative ischaemia and cardiac protein concentrations. The relative odds for the associations of major adverse outcome at 3 months after surgery and postoperative ischaemia or increased serum concentrations of the three proteins were 5.39 [95% confidence intervals 1.16-27.67] for postoperative ischaemia; 5.64 [1.07-31.00] for creatine kinase-MB isoenzyme; 17.00 [2.20-116.54] for troponin T and 13.20 [1.12-135.00] for troponin I. We found troponin T to be the only prospective marker for both major and minor cardiovascular complications (relative odds 10.65 [1.26-252.88]). 相似文献
109.
110.
João Freitas M.D. Rosa Santos B.Sc. Elsa Azevedo M.D. Ovidio Costa Ph.D. Mário Carvalho M.D. A. Falcão de Freitas M.D. Ph.D F.E.S.C. 《Clinical autonomic research》2000,10(5):293-299
Orthostatic intolerance is the development of disabling symptoms upon assuming an upright posture that are relieved partially by resuming the supine position. Postural tachycardia syndrome (POTS) is an orthostatic intolerance syndrome characterized by palpitations because of excessive orthostatic sinus tachycardia, lightheadedness, tremor, and near-syncope. Patients usually undergo extensive medical, cardiac, endocrine, neurologic, and psychiatric evaluation, which usually fails to identify a specific abnormality. The authors investigated the autonomic and hemodynamic profile of patients with POTS and the effectiveness of bisoprolol and fludrocortisone. The authors evaluated 11 female patients with POTS before and after medical treatment with a cardioselective bisoprolol -blocker or fludrocortisone, or both, and 11 age-matched control patients. Variability of heart rate and systolic blood pressure was assessed by fast Fourier transform, and spontaneous baroreceptor gain was assessed by use of the temporal sequences slope and index. Modelflow was used to quantify hemodynamics. Symptoms in all patients improved greatly after medication. The autonomic and hemodynamic impairment observed in patients with POTS, particularly after orthostatic stress, is treated effectively with bisoprolol or fludrocortisone or both. These results need further confirmation in a controlled double-blind study. Proper medical treatment improves dramatically the clinical and autonomic-hemodynamic disturbances observed in patients with POTS. The data support the hypothesis that POTS is the result of a hyperadrenergic activation or hypovolemia during orthostasis. 相似文献