全文获取类型
收费全文 | 17296篇 |
免费 | 1065篇 |
国内免费 | 54篇 |
专业分类
耳鼻咽喉 | 206篇 |
儿科学 | 524篇 |
妇产科学 | 421篇 |
基础医学 | 3298篇 |
口腔科学 | 332篇 |
临床医学 | 1484篇 |
内科学 | 3521篇 |
皮肤病学 | 725篇 |
神经病学 | 1368篇 |
特种医学 | 789篇 |
外国民族医学 | 2篇 |
外科学 | 2443篇 |
综合类 | 116篇 |
一般理论 | 9篇 |
预防医学 | 1071篇 |
眼科学 | 223篇 |
药学 | 1034篇 |
中国医学 | 12篇 |
肿瘤学 | 837篇 |
出版年
2021年 | 221篇 |
2020年 | 145篇 |
2019年 | 184篇 |
2018年 | 218篇 |
2017年 | 223篇 |
2016年 | 295篇 |
2015年 | 278篇 |
2014年 | 383篇 |
2013年 | 559篇 |
2012年 | 660篇 |
2011年 | 683篇 |
2010年 | 390篇 |
2009年 | 463篇 |
2008年 | 642篇 |
2007年 | 653篇 |
2006年 | 659篇 |
2005年 | 623篇 |
2004年 | 573篇 |
2003年 | 550篇 |
2002年 | 609篇 |
2001年 | 559篇 |
2000年 | 522篇 |
1999年 | 495篇 |
1998年 | 235篇 |
1997年 | 219篇 |
1996年 | 225篇 |
1995年 | 168篇 |
1994年 | 179篇 |
1993年 | 153篇 |
1992年 | 294篇 |
1991年 | 314篇 |
1990年 | 306篇 |
1989年 | 316篇 |
1988年 | 304篇 |
1987年 | 268篇 |
1986年 | 271篇 |
1985年 | 260篇 |
1984年 | 198篇 |
1983年 | 172篇 |
1982年 | 123篇 |
1980年 | 120篇 |
1979年 | 197篇 |
1978年 | 141篇 |
1977年 | 128篇 |
1976年 | 118篇 |
1975年 | 153篇 |
1974年 | 153篇 |
1973年 | 143篇 |
1972年 | 140篇 |
1971年 | 126篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Objective: Aprotinin is widely used in heart surgery for reduction of intraoperative blood loss. But recent reports presenting results from rat aorta experiments claimed that aprotinin selectively impairs endothelium-dependent relaxation (EDR) as well as basal NO availability in concentrations similar to doses routinely used in cardiovascular surgery. An impairment of coronary EDR by aprotinin would be a great danger for any cardiothoracic intervention. We therefore tested the influence of aprotinin in the coronary arteries of a non-rodent species. Methods: Fresh coronary arteries of pigs were obtained from the local slaughterhouse and transported to our laboratory in cold oxygenated Krebs–Henseleit solution. Five-millimeter long rings were consecutively tested with or without aprotinin in concentrations of 500 KIU/ml (n = 7) or 1000 KIU/ml (n = 6) in oxygenated normothermic Krebs–Henseleit solution. PGF2 (10 μmol/l) was used for inducing contraction and substance P (10 nmol/l) for inducing EDR, which was calculated in percentage of the precontraction. Indomethacin (10 μmol/l) was added in all measurements to eliminate the influence of prostaglandins. In additional similar experiments (n = 5), the influence of 1000 KIU/ml aprotinin on the EDR caused by the endothelium-derived hyperpolarizing factor (EDHF) was tested using l-NNA (300 μmol/l) to block all NO formation. Results: The EDR of pig coronaries (82 ± 5% or 80 ± 5% of the precontraction in the control tests before and after aprotinin exposure) was not significantly changed by 500 KIU/ml aprotinin (78 ± 7%). A small, but significant reduction of less than 1/10 of the EDR was induced by 1000 KIU/ml aprotinin (74 ± 5%). After accounting for l-NNA for NO blockage, no aprotinin-related difference remained (59 ± 6% vs 60 ± 6% in controls). Conclusion: For clinically relevant concentrations of aprotinin up to 500 KIU/ml, no significant reduction of the EDR can be found in epicardial coronary arteries of the pig. For higher doses of 1000 KIU/ml, a reduction in NO production seems to be the cause of the small but significant reduction of the EDR by aprotinin. Therefore, danger for impairment of coronary EDR by aprotinin at clinical dosage levels, as suggested by studies on rat aortas, seems to be absent in coronary arteries of a large mammalian model. 相似文献
52.
W Heidemann J H Fischer J Koebke C Bussmann K L Gerlach 《Mund-, Kiefer- und Gesichtschirurgie》2003,7(5):283-288
AIMS. Comparison of the degradation of poly(D,L)lactide (Resorb X) or poly(lactide-co-glycolide) (LactoSorb) in vivo. MATERIAL AND METHODS. LactoSorb and Resorb X osteosynthesis plates were fixed at the lateral aspect of the femora of 26 Chinchilla rabbits using the respective osteosynthesis screws. After intraperitoneal injection of fluorochromes the screw plate bone blocks were resected after 1, 6, 12, 14, 16, 21, 26 months and radiologic, histologic as well as fluorescence microscopic examinations were carried out. RESULTS. Newly formed bone was detectable above and beneath the polymers 1 month after the implantation. The implants were totally covered by newly formed bone after 6 months. While the LactoSorb screws were found to be as birefringent as after 1 month, in the Resorb X screws a continuous resorption by phagocytizing marrow cells starting from the periphery was detectable. Resorb X was totally resorbed in histologic slides 12 months after implantation, while total resorption of LactoSorb lasted 14 months; both polymers were replaced by marrow cells. Bone remodeling was not finished 26 months after implantation in both polymers. CONCLUSION. Resorption of Resorb X was finished earlier than the resorption of LactoSorb. Both materials were found by fluorescence microscope to be completely resorbed after 12 or 14 months, but bone remodeling of the screw holes was not yet finished 26 months after implantation. 相似文献
53.
54.
55.
David Quarcoo Tanja C Fischer Nora Peckenschneider David A Groneberg Pia Welker 《Journal of occupational medicine and toxicology (London, England)》2009,4(1):8
Background
Neurotrophin 3 (NT-3) is a member of the neurotrophin family, a group of related proteins that are known to regulate neuro-immune interactions in allergic diseases. Their cellular sources and role in the recruitment of mast cell precursors in atopic dermatitis have not been characterized in detail so far. 相似文献56.
57.
For cardio-pulmonary resuscitation there are standardized treatment concepts, but there have been few prospective investigations examining the efficacy of prehospital advanced trauma life support and its effect on the outcome in patients with severe head injury and multiple trauma treated within the German emergency system. The results of this study underline the importance of intensive prehospital treatment and highlight some problems that should be taken into account in future in the training of emergency physicians. Methods. A total of 179 patients with cerebral trauma were investigated. Data obtained included demographic and logistic data of the patients and the emergency physicians, diagnoses and treatment at the scene of the accident and state of the patient on admission in each case. Having divided the patients into three groups by severity of the trauma, we distinguished between sufficient and insufficient treatment and assessed infusion therapy, ventilatory support, positioning and immobilization, and analgesic and sedative therapy. For statistical analysis of the data we used χ2-test and Fisher's exact test. P<0.05 was considered significant. Results. There were 102 patients who had sustained a cerebral trauma without other life-threatening lesions (score 1), 40 with multiple trauma (score 2) and 37 with multiple trauma (score 3). On average 2.4?IV lines were established and the patients received 1186±765?cc of crystalloid in addition to 801±411?cc of colloid fluids. In all groups, patients who received adequate infusion therapy had a better outcome; even in the group with score 1 significantly fewer had a fatal outcome. In all, 167 (93%) patients had endotracheal tubes placed, and in 150 cases (84%) ventilatory therapy was considered sufficient. The proportion of score 1 patients with sufficient ventilatory support who had a fatal outcome was significantly lower than that in the group with insufficient treatment. In patients with multiple trauma we could not separate the benefits of sufficient respiratory therapy and infusion therapy. In only 54% of the cases a vacuum mattress was used and in only 41% the patients were positioned with the upper part of the body elevated by 30°. These were 28 patients (16%) who received neither analgesics nor sedatives. Regardless of the quality of prehospital treatment of isolated head injury, a Glasgow Coma Scale (GCS) score lower than 5 involved a very high mortality and all patients with a GCS score of 9 or more survived. In the group with GCS scores between 5 and 8, however, significantly more of the patients who received adequate treatment survived (82.5% vs 40%). Conclusions. The present study confirms that sufficient advanced trauma life support can improve the outcome of trauma victims with cerebral trauma. Adequate infusion and respiratory therapy reduce the mortality among such patients significantly. In patients with multiple trauma a clear positive effect of generous infusion therapy also is evident. The clearest effect of sufficient prehospital treatment is seen in patients with isolated cerebral trauma and a GCS score between 5 and 8. These results demonstrate the importance of advanced trauma life support and show emphatically that the so-called scoop-and-run strategy should be abandoned when resources are available for extended preclinical emergency treatment. On the other hand, we detected some problem areas in the prehospital treatment of trauma victims, such as positioning, immobilization and drug therapy with analgesics and sedatives. These findings allow us to pinpoint specific points that should be stressed in the training of emergency physicians and paramedics. 相似文献
58.
MICHAEL SCHLÜTER PH.D. RICCARDO CAPPATO M.D. FEIFAN OUYANG M.D. MATTHIAS ANTZ M.D. CATARINA A. SCHLÜTER M.D. KARL-HEINZ KUCK M.D. 《Journal of cardiovascular electrophysiology》1997,8(12):1366-1372
Dormant Accessory Pathways. Introduction : Recurrence of clinical symptoms after radiofrequency catheter ablation of an accessory atrioventricular pathway (AP) may be due to the late manifestation of an additional AP that was not detected during the initial ablation session. It was the purpose of this study to elucidate the phenomenon of these "dormant" APs.
Methods and Results : Of 1280 consecutive patients who underwent radiofrequency catheter ablation of an AP, 54 patients (4.2 %) developed clinical symptoms postablation, necessitating a repeat ablation session. Recurrence of conduction over the AP targeted al the initial ablation session was found in 45 patients, whereas in the other 9 patients (0.7%) the manifestation of a previously unnoticed AP had caused symptom recurrence. Retrospective analysis of the data from these patients' ablation sessions revealed that the late manifesting AP was ablated at a site clearly different from that of the initially targeted AP, and that the manifestation of conduction over a previously "dormant" AP occurred significantly later than the recovery of a presumably ablated AP. Seven (78%) of the 9 "dormant" APs were concealed, and none exhibited decremental conduction properties.
Conclusion : The incidence of clinical recurrences mediated by the late manifestation of conduction over a previously "dormant" AP is low. The lack of an anatomic vicinity of these predominantly concealed APs with the initially targeted AP and the lack of evidence for their presence during the initial ablation session suggest intermittent conduction as the most likely explanation for their late manifestation. 相似文献
Methods and Results : Of 1280 consecutive patients who underwent radiofrequency catheter ablation of an AP, 54 patients (4.2 %) developed clinical symptoms postablation, necessitating a repeat ablation session. Recurrence of conduction over the AP targeted al the initial ablation session was found in 45 patients, whereas in the other 9 patients (0.7%) the manifestation of a previously unnoticed AP had caused symptom recurrence. Retrospective analysis of the data from these patients' ablation sessions revealed that the late manifesting AP was ablated at a site clearly different from that of the initially targeted AP, and that the manifestation of conduction over a previously "dormant" AP occurred significantly later than the recovery of a presumably ablated AP. Seven (78%) of the 9 "dormant" APs were concealed, and none exhibited decremental conduction properties.
Conclusion : The incidence of clinical recurrences mediated by the late manifestation of conduction over a previously "dormant" AP is low. The lack of an anatomic vicinity of these predominantly concealed APs with the initially targeted AP and the lack of evidence for their presence during the initial ablation session suggest intermittent conduction as the most likely explanation for their late manifestation. 相似文献
59.
Prospective study of the occurrence of monoclonal gammapathies following bone marrow transplantation in young children 总被引:2,自引:0,他引:2
We have prospectively studied the occurrence of monoclonal serum immunoglobulins in 38 recipients of BMT. Patients were young children with primary immunodeficiencies (n = 31), other inherited diseases (n = 4), leukemia (n = 2), or aplastic anemia (n = 1). Twenty-nine received an HLA-nonidentical marrow and nine an HLA-identical marrow. Serum monoclonal immunoglobulins were detected by the immunofixation method. Monoclonal immunoglobulins were found in 26 patients. Monoclonal components were more frequently detected in patients with primary severe T cell deficiencies (21/25) rather than in the other patients (6/13). In 7 of 29 recipients of HLA-nonidentical transplants, versus 0 out of 9 recipients of HLA-identical transplants, serum monoclonal immunoglobulins were found associated with a B lymphocyte proliferation syndrome due to an Epstein-Barr virus infection. In this group, monoclonal immunoglobulins were detected early, prior to the onset of the clinical syndrome. The simultaneous occurrence of several monoclonal immunoglobulins was more frequent in these patients, while monoclonal immunoglobulin concentrations increased faster, especially those of IgM isotype. These characteristics may allow in patients at risk (recipients with primary T cell immunodeficiencies and receiving HLA-nonidentical transplantation) an earlier diagnosis of B lymphocyte proliferative syndrome that may eventually lead to early and more efficient therapy. 相似文献
60.
M Nehéz G W Fischer H Scheufler R Schmidt T Sipos I Dési 《Ecotoxicology and environmental safety》1992,24(1):13-16
The organophosphorus herbicide buminafos (O,O-dibutyl-(1-butylaminocyclohexyl)-phosphonate) was tested for its acute toxic, cytogenetic, and embryotoxic activity on different strains of mice. The oral LD50 value for male NMRI mice was determined to be 3500 mg/kg. Single oral doses of 175, 1000, and 2000 mg/kg did not cause any significant enhancement in the percentage of chromosome aberrations in bone marrow cells of male NMRI mice. After oral administration of 500 and 1000 mg/kg buminafos to pregnant Halle:DBA and Halle:AB mice at Days 6-15 of gestation no embryotoxic effects were observed. The cytogenetic inactivity of buminafos in the bone marrow chromosome assay corresponds to negative findings in other mutagenicity tests. 相似文献