首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4745篇
  免费   175篇
  国内免费   63篇
耳鼻咽喉   74篇
儿科学   136篇
妇产科学   47篇
基础医学   719篇
口腔科学   126篇
临床医学   268篇
内科学   1080篇
皮肤病学   67篇
神经病学   333篇
特种医学   189篇
外科学   933篇
综合类   16篇
一般理论   1篇
预防医学   67篇
眼科学   88篇
药学   233篇
中国医学   17篇
肿瘤学   589篇
  2023年   17篇
  2022年   31篇
  2021年   57篇
  2020年   44篇
  2019年   66篇
  2018年   93篇
  2017年   61篇
  2016年   92篇
  2015年   95篇
  2014年   100篇
  2013年   174篇
  2012年   259篇
  2011年   303篇
  2010年   165篇
  2009年   155篇
  2008年   271篇
  2007年   330篇
  2006年   280篇
  2005年   351篇
  2004年   340篇
  2003年   313篇
  2002年   356篇
  2001年   77篇
  2000年   63篇
  1999年   77篇
  1998年   65篇
  1997年   60篇
  1996年   49篇
  1995年   64篇
  1994年   56篇
  1993年   64篇
  1992年   39篇
  1991年   33篇
  1990年   24篇
  1989年   34篇
  1988年   32篇
  1987年   32篇
  1986年   31篇
  1985年   19篇
  1984年   27篇
  1983年   21篇
  1982年   14篇
  1981年   19篇
  1980年   19篇
  1979年   10篇
  1978年   11篇
  1977年   14篇
  1976年   12篇
  1974年   11篇
  1972年   7篇
排序方式: 共有4983条查询结果,搜索用时 15 毫秒
71.
A 32-year-old man presented with an arachnoid cyst of the posterior fossa manifesting as cervical syringomyelic myelopathy. Magnetic resonance (MR) imaging demonstrated edematous enlargement and T2 prolongation of the cervical spinal cord, indicating a "presyrinx" state. MR imaging showed the inferior wall of the cyst, which disturbed cerebrospinal fluid (CSF) pulsatile movement between the intraspinal and intracranial subarachnoid spaces. The cyst wall was fenestrated with a neuroendoscope. The presyrinx state and the CSF movement improved. Posterior fossa arachnoid cyst, as well as Chiari malformation, can cause CSF flow disturbance at the craniocervical junction and syringomyelia. Endoscopic fenestration is less invasive than foramen magnum decompression and should be the procedure of choice.  相似文献   
72.
External pneumatic compression (EPC) devices prevent lower extremity deep venous thrombosis (DVT) by reducing stasis. There is a widely held belief that they also enhance endogenous fibrinolysis; however, recent studies of tissue plasminogen activator (the primary activator of fibrinolysis) and plasminogen activator inhibitor-1 (the primary inhibitor of fibrinolysis) failed to confirm this. The hypothesis of this study was that EPC devices increase the level of urokinase plasminogen activator (uPA), a second activator of fibrinolysis. This was a prospective trial in which 44 subjects who underwent major abdominal surgery were randomized to receive unfractionated heparin injections, thigh-length sequential EPC devices, or both for DVT prophylaxis. Prophylaxis was begun immediately before surgical incision and continued until postoperative day 5 or discharge. Venous blood samples were collected from an antecubital vein for measurement of systemic uPA levels and from the common femoral vein for measurement of regional uPA levels. Samples were collected the day before surgery, after induction of anesthesia but before surgical incision, and on postoperative days 1, 3, and 5. uPA levels (ng/mL) were measured with an enzyme-linked immunoassay. Baseline uPA levels (0.41 to 0.56 ng/mL; P >.05, analysis of variance with repeated measures) were similar among the three groups. uPA levels did not change after surgery in systemic or regional blood samples in any group. There were no significant differences in systemic or regional uPA levels in the groups treated with EPC devices relative to those treated with heparin at any time point (P >.05, analysis of variance with repeated measures). Enhancement of fibrinolysis with EPC devices remains unproven; the findings reported here suggest that effective DVT prophylaxis can only be assured when the devices are used in a manner that reduces venous stasis.  相似文献   
73.

Background

Trans-right axillary aortic valve replacement (TAX-AVR) remains uncommon. We developed a special method to pull the heart closer to the right chest wall to make the surgery as easy and safe as aortic valve replacement via median sternotomy. Because the retraction sutures lifting the ascending aorta and aortic root are arranged circularly around the wound, we named this technique “Stonehenge technique”.

Methods

We examined 47 patients who underwent aortic valve replacement through a small right infra-axillary thoracotomy as the initial surgical therapy. These patients were divided into two groups: the conventional TAX-AVR group that underwent AVR via the conventional small right axillary incision approach (n?=?20) and the TAX-AVR with SH group that underwent AVR with the Stonehenge technique (n?=?27).

Results

The aortic cross-clamp and the extracorporeal circulation time were significantly shorter in the TAX-AVR with SH group than in the conventional TAX-AVR group (conventional TAX-AVR group: 125.5?±?47.9; TAX-AVR with SH group: 96.0?±?14.0, p?=?0.004, and conventional TAX-AVR group: 163.8?±?55.9; TAX-AVR with SH group: 140.0?±?16.8, p?=?0.04).

Conclusion

The outcomes of this technique depend on the site of the retraction sutures in the opened pericardium, direction of pull, amount of force applied, and precautions taken. If performed correctly, the ascending aorta and the root can be pulled from the wound to within the surgeon’s fingers’ reach, thereby reducing aortic cross-clamp and extracorporeal circulation times in group of minimally invasive aortic valve replacement via right infra-axillary thoracotomy.
  相似文献   
74.
Chondroblastoma of the temporal bone   总被引:2,自引:0,他引:2  
A rare case of chondroblastoma arising from the temporal bone that occurred in a 60-year-old woman is reported. The tumor appeared well demarcated and osteolytic on the radiographs. CT scan clearly depicted marginal and central calcification in the tumor. MR imaging demonstrated two components in the tumor: a solid component with predominantly low signal intensities on both T1- and T2-weighted sequences, and a multilocular cystic component with T1- and T2-elongation and fluid-fluid levels on the T2-weighted images. Postcontrast MR imaging revealed marked enhancement in the solid component and the septa of the cystic component.  相似文献   
75.
A 65-year-old woman with a 48-year history of Behçet’s disease associated with nephrotic syndrome is described. Immunofluorescence study revealed IgA nephropathy. Following treatment with an angiotensin II type-I receptor-blocker, an anti-platelet drug, and an HMG-CoA reductase inhibitor, accompanied by dietary restrictions of protein and sodium, proteinuria was markedly decreased. This report describes our experience with a rare entity of Behçet’s disease complicated by nephrotic syndrome due to IgA nephropathy. Routine urine examination and renal biopsy are needed for the detection and diagnosis of renal problems with Behçet’s disease.  相似文献   
76.
77.
Primary testicular plasmacytoma with hydrocele of the testis   总被引:2,自引:0,他引:2  
A case of primary testicular plasmacytoma complicated with hydrocele of the testis is reported. An 86-year-old man presented with hydrocele of the right testis. High inguinal orchiectomy was performed as the preoperative aspiration cytology of the hydrocele fluid showed atypical cells. Immunohistochemical study of the right testis revealed testicular plasmacytoma positive for IgG. He remained well 9 months after the orchiectomy. This is the second reported case where the preoperative diagnosis of testicular plasmacytoma was made based on the hydrocele fluid cytology.  相似文献   
78.
A 54-year old man was admitted to our hospital because of high fever, productive cough and purpura in both legs in June 2005. Urinalysis showed microscopic hematuria and proteinuria. Chest radiograph showed consolidation of right upper field. Because acid-fast bacilli and polymerase chain reaction test for Mycobacterium tuberculosis were positive in bronchial lavage fluid, we made a diagnosis of pulmonary tuberculosis, and prescribed antituberculosis therapy with isoniazid, rifampicin, ethambutol and pyrazinamide. In addition, anaphylactoid purpura was diagnosed by skin biopsy. In July 2005, renal function was deteriorated and nephrosis appeared. We treated with corticosteroid in addition to antituberculosis therapy. His symptoms and renal dysfunction improved. We report a rare case of an anaphylactoid purpura following occurence of pulmonary tuberculosis.  相似文献   
79.
OBJECTIVE: Stroke-prone spontaneously hypertensive rats (SHRSP) are known to have sympathetic hyperactivity to various stimuli. In the search for 'intermediate phenotypes' inferring the function of hypertension genes, the present study assessed responsiveness to cold stress in a congenic strain derived from SHRSP/Izm and Wistar-Kyoto/Izm (WKY/Izm). DESIGN: A congenic strain, WKYpch1.0, was established by 10 generations of backcrossing to transfer the chromosomal fragment between D1Wox29 and D1Arb21 of SHRSP to WKY. This fragment covered the 100:1 confidence interval of the quantitative trait locus (QTL) for blood pressure identified in a previous study. Response to cold stress was studied by exposing rats to 4 degrees C for 4 h. Blood pressure was monitored with telemetry. Urine was collected during the exposure, and urinary concentrations of catecholamines were measured by high-performance liquid chromatography. RESULTS: Under the cold stress, urinary excretion of norepinephrine (NE) and vanillylmandelic acid (VMA), as well as the plasma level of NE, was significantly greater in WKYpch1.0 than in WKY. The increase in blood pressure during the cold stress was also greater in WKYpch1.0 than in WKY. Further, neonatal chemical sympathectomy using guanethidine abolished the exaggerated response in blood pressure and in urinary excretion of NE and VMA in WKYpch1.0. CONCLUSION: These results suggested that the QTL region on rat chromosome 1 harbored genes responsible for the exaggerated response of the sympathetic nervous system to the cold stress. The relationship of this with the pathogenesis of hypertension should be elucidated in future studies.  相似文献   
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号