全文获取类型
收费全文 | 3594篇 |
免费 | 357篇 |
国内免费 | 22篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 91篇 |
妇产科学 | 67篇 |
基础医学 | 528篇 |
口腔科学 | 62篇 |
临床医学 | 510篇 |
内科学 | 781篇 |
皮肤病学 | 32篇 |
神经病学 | 284篇 |
特种医学 | 215篇 |
外科学 | 336篇 |
综合类 | 53篇 |
一般理论 | 15篇 |
预防医学 | 467篇 |
眼科学 | 86篇 |
药学 | 170篇 |
中国医学 | 2篇 |
肿瘤学 | 258篇 |
出版年
2021年 | 47篇 |
2020年 | 37篇 |
2019年 | 61篇 |
2018年 | 58篇 |
2017年 | 56篇 |
2016年 | 74篇 |
2015年 | 59篇 |
2014年 | 65篇 |
2013年 | 105篇 |
2012年 | 153篇 |
2011年 | 163篇 |
2010年 | 114篇 |
2009年 | 115篇 |
2008年 | 162篇 |
2007年 | 187篇 |
2006年 | 181篇 |
2005年 | 137篇 |
2004年 | 154篇 |
2003年 | 121篇 |
2002年 | 112篇 |
2001年 | 97篇 |
2000年 | 111篇 |
1999年 | 93篇 |
1998年 | 71篇 |
1997年 | 62篇 |
1996年 | 48篇 |
1995年 | 50篇 |
1994年 | 46篇 |
1993年 | 45篇 |
1992年 | 75篇 |
1991年 | 72篇 |
1990年 | 70篇 |
1989年 | 84篇 |
1988年 | 69篇 |
1987年 | 62篇 |
1986年 | 56篇 |
1985年 | 77篇 |
1984年 | 47篇 |
1983年 | 38篇 |
1982年 | 33篇 |
1981年 | 38篇 |
1980年 | 30篇 |
1979年 | 47篇 |
1978年 | 41篇 |
1977年 | 32篇 |
1976年 | 28篇 |
1975年 | 33篇 |
1974年 | 32篇 |
1973年 | 28篇 |
1971年 | 23篇 |
排序方式: 共有3973条查询结果,搜索用时 0 毫秒
1.
Developmental regulation of annexin II (Lipocortin 2) in human brain and expression in high grade glioma. 总被引:7,自引:0,他引:7
In experiments to identify molecules that might be important in the pathogenesis of glioblastoma multiforme, the most common malignant brain tumor, we found that annexin II (Lipocortin 2, p36), a likely second messenger in several different mitogenic pathways, was highly expressed in tumor tissue of glioblastoma multiforme (9 of 9) and highly anaplastic astrocytoma (2 of 6), but not in astrocytomas of lower pathological grade (0 of 6). We also detected high levels of annexin II expression in fetal brain during the period when radial glia proliferate, although annexin II expression was not detected in normal adult brain. These data demonstrate that annexin II expression is developmentally regulated in the human central nervous system and suggest that the early progenitor radial glia share important characteristics with highly malignant glial tumors. 相似文献
2.
3.
B. L. Kirkpatrick S. C. Glover D. S. Reeves A. P. MacGowan 《Postgraduate medical journal》1997,73(863):565-570
We have reviewed the incidence, type and site of microbiologically proven bacterial infection occurring in 52 patients with the acquired immunodeficiency syndrome (AIDS) who presented to Southmead Hospital, Bristol between 1990 and 1994. A total of 30 (58%) patients had significant bacterial isolates. The majority of infections were community acquired. Overall, more infections were caused by Gram-negative organisms but Gram-positive organisms predominated in bacteraemia. Mycobacterium avium intracellulare (MAI) caused infection in the largest number of patients, followed by Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas sp, and Campylobacter sp. When individual episodes of infection were considered, after MAI, Haemophilus influenzae, Streptococcus pneumoniae and Pseudomonas sp were the organisms most frequently isolated; often these same organisms caused recurrent chest infection. Bacterial infections in AIDS patients are common and although they generally respond well to antimicrobial chemotherapy there is a high recurrence rate, particularly in the respiratory tract, which is the commonest site of infection. 相似文献
4.
5.
6.
Effect of inoculum size and medium on activity of seven antimicrobial agents against Bacteroides fragilis strains 总被引:2,自引:0,他引:2
Antimicrobial activity of cefoxitin, cefotetan, cefotaxime, ceftizoxime, ceftazidime, imipenem, and clindamycin against four inocula of Bacteroides fragilis strains was determined on three different media. The inoculum sizes were 10(4), 10(5), 10(6), and 10(7) colony forming units (CFU) per spot. On all three media, substantial effects of inoculum size on minimal inhibitory concentrations (MIC) of cefotaxime and ceftizoxime were found: the doubled dilution differences in MICs between inocula of 10(7) and 10(4) CFU/spot were 2.2, 2.3, and 2.1 micrograms/ml of cefotaxime and 1.8, 4.4, and 4.0 micrograms/ml of ceftizoxime on Brucella base-laked blood agar, Wilkins-Chalgren agar, and a brain-heart infusion medium, respectively. An inoculum difference found on all three media with ceftazidime may also be of practical significance. There was evidence of larger differences between inocula on the Wilkins-Chalgren agar and brain-heart infusion than on the Brucella agar. 相似文献
7.
The relation between the amplitude of visual responses to a checkerboard stimulus and the degree of lateral displacement of the checks was examined across different check sizes with simultaneously recorded electroretinograms (ERGs) and visual-evoked potentials (VEPs). The amplitudes of both the b-wave and the after-potential of the ERG increase linearly with pattern displacement. However, the major components of the VEP (N70 and P100) were smaller than expected from linearity for both small checks with small displacements (thresholding) and for large checks with large displacements (saturation). These results suggest that the ERG is proportional to the number of receptors stimulated, but the VEP reflects neural processes influenced by the spatial structure of the stimulus. 相似文献
8.
J D Helman J M Leung W H Bellows N Pineda G W Roach J D Reeves J Howse M T McEnany D T Mangano 《Anesthesiology》1992,77(1):47-62
Desflurane, a coronary vasodilator, may induce myocardial ischemia in patients with coronary artery disease. To determine whether desflurane is safe to administer to the at-risk patient population (with known coronary artery disease), we compared the incidence and characteristics of perioperative myocardial ischemia in 200 patients undergoing coronary artery bypass graft (CABG) surgery randomly assigned to receive desflurane (thiopental adjuvant) versus sufentanil anesthesia. Under conditions of hemodynamic control, perioperative ischemia was assessed using continuous echocardiography (precordial: during induction; transesophageal: during surgery) and Holter electrocardiography (ECG); hemodynamics (including pulmonary artery pressure) were measured continuously. Hemodynamic results: During induction, no significant changes in hemodynamics occurred in the sufentanil group, while in the desflurane group, heart rate, systemic and pulmonary arterial pressure increased and stroke volume decreased significantly. During the intraoperative period, the incidence of hemodynamic variations was low in both anesthetic groups; however, the prebypass incidence of tachycardia (greater than 120% of preoperative baseline heart rate) was greater in the desflurane group (4 +/- 7% of total time monitored) than in the sufentanil group (1 +/- 6%) (P = 0.0003). Similarly, the incidence of prebypass hypotension (less than 80% of preoperative baseline systolic arterial blood pressure) was greater in the desflurane group (21 +/- 14%) than in the sufentanil group (15 +/- 16%) (P = 0.01). ECG results: Preoperatively, 15% (28/191) of patients developed ECG ischemia, with no difference between patients who received desflurane, 13% (12/96) or sufentanil, 16% (16/95) (P = 0.6). During anesthetic induction, 9% (9/99) of patients who received desflurane developed ECG ischemia, compared with 0% (0/98) who received sufentanil (P = 0.007). During the prebypass period, 5% (10/197) of patients developed ECG ischemia, with no difference between patients who received desflurane, 7% (7/99) or sufentanil, 3% (3/98) (P = 0.3). Postbypass, 12% (24/194) of patients developed ECG ischemic changes, with no difference between patients who received desflurane, 13% (13/97) or sufentanil, 11% (11/96) (P = 0.9). Echocardiographic results: The incidence of precordial echocardiographic ischemia during anesthetic induction was 13% (5/39) in the desflurane group versus 0% (0/29) in the sufentanil group (P = 0.1). Moderate to severe transesophageal echocardiographic (TEE) ischemic episodes occurred in 12% (21/175) of patients during prebypass, with no significant difference between the desflurane group, 16% (15/91) and the sufentanil group, 7% (6/84) (P = 0.09). TEE ischemic episodes occurred in 27% (49/178) of patients during the postbypass period, with no difference between the desflurane, 29% (27/92) and sufentanil, 25% (22/86) groups (P = 0.7).(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
9.
Ikwunga Wonodi Gloria Reeves Dana Carmichael Ilene Verovsky Matthew T Avila Amie Elliott L Elliot Hong Helene M Adami Gunvant K Thaker 《Movement disorders》2007,22(12):1777-1782
Recent years have witnessed increased antipsychotic treatment of children despite limited long‐term safety data in children. In this study, motor side effects associated with the use of antipsychotic drugs in children were examined in a sample of pediatric psychiatric patients. Child and adolescent psychiatric patients receiving antipsychotics (most were on atypicals) for 6 months or longer (n = 118) were compared with antipsychotic‐naïve patients (n = 80) with similar age, sex ratio, and diagnoses. Only 19% of patients on antipsychotics had ever experienced psychotic symptoms. Eleven children (9%) on antipsychotics exhibited dyskinesia, when compared with 0 in the naïve group (P = 0.003, Fisher's exact test). Nine of 62 African–American children (15%) on antipsychotics exhibited dyskinesia, when compared with only 4% (2 of 52) of European–American children (P = 0.003, Fisher's exact test). Children treated with antipsychotic drugs might experience a significant risk of dyskinesia even when treated only with atypical antipsychotics. Ethnicity might also be a risk factor for dyskinesia in children. Side‐effect profile of the atypical antipsychotic drugs in children may be much different than that in adults. © 2007 Movement Disorder Society 相似文献
10.