全文获取类型
收费全文 | 161494篇 |
免费 | 10308篇 |
国内免费 | 1220篇 |
专业分类
耳鼻咽喉 | 2255篇 |
儿科学 | 3028篇 |
妇产科学 | 3746篇 |
基础医学 | 24037篇 |
口腔科学 | 3348篇 |
临床医学 | 15227篇 |
内科学 | 30783篇 |
皮肤病学 | 4341篇 |
神经病学 | 12053篇 |
特种医学 | 8122篇 |
外科学 | 21887篇 |
综合类 | 2160篇 |
现状与发展 | 5篇 |
一般理论 | 81篇 |
预防医学 | 9718篇 |
眼科学 | 4308篇 |
药学 | 13655篇 |
中国医学 | 1597篇 |
肿瘤学 | 12671篇 |
出版年
2023年 | 987篇 |
2022年 | 2739篇 |
2021年 | 4824篇 |
2020年 | 2465篇 |
2019年 | 3583篇 |
2018年 | 4401篇 |
2017年 | 3232篇 |
2016年 | 4187篇 |
2015年 | 5637篇 |
2014年 | 6908篇 |
2013年 | 8371篇 |
2012年 | 12642篇 |
2011年 | 12275篇 |
2010年 | 7250篇 |
2009年 | 6067篇 |
2008年 | 9256篇 |
2007年 | 9123篇 |
2006年 | 8378篇 |
2005年 | 7979篇 |
2004年 | 7124篇 |
2003年 | 6188篇 |
2002年 | 5373篇 |
2001年 | 4378篇 |
2000年 | 4029篇 |
1999年 | 3265篇 |
1998年 | 1317篇 |
1997年 | 997篇 |
1996年 | 958篇 |
1995年 | 869篇 |
1994年 | 755篇 |
1993年 | 648篇 |
1992年 | 1574篇 |
1991年 | 1572篇 |
1990年 | 1357篇 |
1989年 | 1243篇 |
1988年 | 1162篇 |
1987年 | 1034篇 |
1986年 | 1014篇 |
1985年 | 883篇 |
1984年 | 645篇 |
1983年 | 565篇 |
1982年 | 401篇 |
1981年 | 381篇 |
1980年 | 339篇 |
1979年 | 519篇 |
1978年 | 408篇 |
1977年 | 390篇 |
1976年 | 345篇 |
1974年 | 358篇 |
1973年 | 327篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
PURPOSE: We examined the efficacy of potassium citrate based medical prophylaxis for preventing upper urinary calculous recurrence, and compared it with the stone recurrence rate in patients who only received intermittent or no medical prophylaxis. MATERIALS AND METHODS: We retrospectively reviewed the records of 493 patients with upper urinary calculi, of whom 237 men and 76 women with a mean age of 56.1 and 51.4 years, respectively, were enrolled in the study. Of the 313 participants 64 (group 1, 20.4%) received regular medical prophylaxis for 24 to 42 months (mean 27.8), 80 (group 2, 25.6%) received intermittent medical prophylaxis for 1.5 to 19 months (mean 7.9) and 169 (group 3, 54%) did not receive any medical prophylaxis. RESULTS: At midterm followup of 24 to 60 months 107 patients (34.2%) had stone recurrence. In group 1 the stone recurrence rate was 7.8%, which was significantly less (p <0.001) than in groups 2 (30%) and 3 (46.2%). Similarly new calculous events in patients with a history of multiple stone recurrence were less frequent in group 1 than in groups 2 and 3 (9.7, 47.4 and 52.2%, respectively, p <0.001). Multiple stone recurrence history, hypercalciuria, hyperuricosuria and calcium oxalate dihydrate calculi were independent risk factors for stone recurrence. CONCLUSIONS: Regular medical prophylaxis may effectively prevent stone recurrence regardless of previous treatment modalities, stone composition, metabolic abnormalities and stone-free status. Cost effectiveness, patient compliance and gastrointestinal upset may limit patient acceptability and clinical use of medical prophylaxis. However, patients with a history of multiple stone recurrence, calcium oxalate dihydrate stones, hypercalciuria and hyperuricosuria benefit from regular medical prophylaxis. 相似文献
992.
Cell-matrix interactions have major effects upon phenotypic features such as gene regulation, cytoskeletal structure, differentiation and aspects of cell growth control. Detachment from the matrix epithelial cells induces programmed cell death, and this cell detachment induced apoptosis has been referred to as 'anoikis'. This study was undertaken to determine whether apoptosis is induced by inhibition of contact with extracellular matrix (ECM) in collecting duct cells and to investigate the signaling mechanisms of the process. Upon detachment from ECM, mouse inner medullary collecting duct cells (mIMCD-3) and mouse outer cortical collecting duct cells (M-1), which were derived from an SV40 transgenic mouse, entered into programmed cell death. Forced suspension of mIMCD-3 or M-1 cells did not affect the expression of Bcl-2-related proteins and did not activate c-Jun NH(2)-terminal kinase. Detachment of cells from ECM activated p38 mitogen-activated protein kinase (p38), but its inhibition with SB203580 did not protect cells from anoikis. Detachment of cells from matrix inhibited NF-kappaB activity, and the inhibition of NF-kappaB activity by overexpression of nonphosphorylatable I-kappaB increased detachment-induced apoptotic cell death in M-1 cells. Forced suspension of M-1 cells still activated p53 activity. Caspase-8 was activated during anoikis, but the time course of its activation was in accordance with DNA fragmentation. These results indicate that detachment from ECM induces apoptosis in the kidney collecting duct cells. Changes in expression levels of Bcl-2-related proteins or activation of JNK/p38 kinase are not critical for anoikis. Decrease in NF-kappaB activity and activation of p53 induced by inhibition of interaction with ECM play roles in anoikis in SV-40-transformed collecting duct cells. Caspase-8 is activated during detachment-induced apoptosis, the mechanisms of which are independent of activation of cell death receptors. Copyright Copyright 1999 S. Karger AG, Basel 相似文献
993.
994.
995.
McMahon PJ Dettling J Sandusky MD Tibone JE Lee TQ 《The Journal of bone and joint surgery. British volume》1999,81(3):406-413
Surgical treatment for traumatic, anterior glenohumeral instability requires repair of the anterior band of the inferior glenohumeral ligament, usually at the site of glenoid insertion, often combined with capsuloligamentous plication. In this study, we determined the mechanical properties of this ligament and the precise anatomy of its insertion into the glenoid in fresh-frozen glenohumeral joints of cadavers. Strength was measured by tensile testing of the glenoid-soft-tissue-humerus (G-ST-H) complex. Two other specimens of the complex were frozen in the position of apprehension, serially sectioned perpendicular to the plane containing the anterior and posterior rims of the glenoid, and stained with Toluidine Blue. On tensile testing, eight G-ST-H complexes failed at the site of the glenoid insertion, representing a Bankart lesion, two at the insertion into the humerus, and two at the midsubstance. For those which failed at the glenoid attachment the mean yield load was 491.0 N and the mean ultimate load, 585.0 N. At the glenoid region, stress at yield was 7.8 +/- 1.3 MPa and stress at failure, 9.2 +/- 1.5 MPa. The permanent deformation, defined as the difference between yield and ultimate deformation, was only 2.3 +/- 0.8 mm. The strain at yield was 13.0 +/- 0.7% and at failure, 15.4 +/- 1.2%; therefore permanent strain was only 2.4 +/- 1.1%. Histological examination showed that there were two attachments of the anterior band of the inferior glenohumeral ligament at the site of the glenoid insertion. In one, poorly organised collagen fibres inserted into the labrum. In the other, dense collagen fibres were attached to the front of the neck of the glenoid. 相似文献
996.
Spontaneous regression of periodontoid pannus mass in psoriatic atlantoaxial subluxation. Case report 总被引:4,自引:0,他引:4
STUDY DESIGN: A case report of a 41-year-old man with psoriasis who had cervical myelopathy caused by atlantoaxial subluxation and periodontoid pannus mass. OBJECTIVE: To describe the possible mechanism underlying the periodontoid pannus formation and the optimal treatment for such cases. SUMMARY OF BACKGROUND DATA: Atlantoaxial subluxation causing spinal cord compression at the craniocervical junction may develop in patients with rheumatoid or psoriatic arthritis. Periodontoid pannus formation plays an important role in compromising the anteroposterior diameter of the spinal canal and in causing neurologic deficits. Transoral transpharyngeal excision of the pannus is sometimes thought necessary for anterior decompression of the spinal cord. Spontaneous resolution of the periodontoid pannus after posterior atlantoaxial fusion and fixation has been documented in rheumatoid arthritis, but not in psoriatic arthritis. METHODS: The patient underwent posterior atlantoaxial fusion and Halifax fixation. RESULTS: The patient experienced clinical improvement. Regression of the periodontoid pannus mass was observed on magnetic resonance imaging. CONCLUSIONS: Posterior fusion and instrumentation resulted in spontaneous regression of the pannus mass and symptomatic relief. This report provides evidence that atlantoaxial instability may be the sine qua non for the formation of periodontoid pannus, and that amelioration of such instability leads to spontaneous resolution of the pannus mass. 相似文献
997.
We report a girl who developed severe and fatal hyperkalemia following rapid and massive blood transfusion during surgery. She was 7-year-old, 20-kg in weight, and received wide resection of the femoral bone with custom prosthesis implant because of malignant femoral osteosarcoma. During the procedure, bleeding was active and profuse and amounted to about 3,000 mL in 4 h, eventuating in shock. Despite rapid transfusion with 15 units of packed red blood cells (RBC) still she remained hypotensive and hypovolemic. When we switched to give her whole blood, actually 100 mL having been given, widening of QRS complex followed immediately by cardiac arrest developed. Cardiopulmonary resuscitation although started at once was unsuccessful. At this juncture, arterial blood gas analysis showed acidosis and severe hyperkalemia (10.3 mmol/L), possibly resulting from transfusion of blood of older storage. The case reminded us once again the importance and necessity of the use of potassium-low blood component (fresh, saline-washed RBCs) in case of massive and rapid blood transfusion especially in pediatric patients with hypovolemia and low cardiac output. 相似文献
998.
Acute liver failure includes a constellation of clinical conditions resulting from rapid loss of hepatocyte function. The anesthesiologist may often be asked to anesthetize a patient with acute liver failure before the etiological entity of disease can be completely clarified. Most of the previous reports were concentrated in obstetric or hepatological periodicals. Reports about anesthesia for such patients are scanty. We present a case about a near term pregnant woman with a complication diagnosed as impending acute liver failure, who received total intravenous anesthesia for emergent cesarean section. Pros and cons of different anesthetic techniques for this condition are discussed. 相似文献
999.
Mouse-to-rat testicle transplantation 总被引:4,自引:0,他引:4
Lee S Wang Y Kim S Cho C Tarin T Sileshi B Yoon JH Mazzoni G Youngkin T Wolf P Gittes RF 《Microsurgery》1999,19(2):66-70
This report details mouse-to-rat testicular transplantation with immediate revascularization. Donor preparation involved grafting a long segment of aorta and inferior vena cava (IVC) containing the testicular artery and vein. The graft aorta and IVC were anastomosed to the rat aorta and IVC, respectively. Vasovasostomy was completed and the scrotal epithelia were anastomosed to draw the graft toward the host scrotal sac. Twenty-nine of 53 transplants were determined to be viable. Histologically, 6- to 18-hr-old grafts displayed moderate to minimal polymorphonuclear neutrophil (PMN) infiltrates. Ischemia set in somewhere between 18-24 hr postoperatively. Beyond 24 hr the grafts displayed progressive infiltration of PMN and perivascular and intertubular lymphocytes, disorganization of the germinal epithelium, and cessation of spermatogenesis. 相似文献
1000.
Lee S Wang Y Mao L Cho C Kim S Tarin T Kim DH Mazzoni G Fazi M Nozawa M Lee D Sileshi B Wei W Lentini A Yoo CH Youngkin T Wolf P D'Silva M Gittes RF 《Microsurgery》1999,19(2):83-88
This periodic report includes intermittent results of consecutive pancreaticoduodenal (Pd) and kidney (Kt) transplants in inbred rats and results on double kidney transplants that did not follow sequential transplant protocol. Eight 24-month-old Lewis pancreas, kidney, and aorta served histological controls showing normal histological architecture with no atherosclerosis developed in the aorta. Thirty-four month old pancreas and thirty-two month old kidneys, which resided in young hosts for at least three occasions, appeared as youthful Pd and Kt grafts. They show normal histological appearance for more than the expected life span of a Lewis rat. The fact that not only pancreases but also kidneys outlived their host leads to the study of other different organs' viability as aged valuable grafts. Nevertheless, the threats by the development of atherosclerosis in graft-associated aortas resulted in slow progression of the follow-ups. 相似文献