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   7566篇
  免费   387篇
  国内免费   44篇
耳鼻咽喉   118篇
儿科学   255篇
妇产科学   347篇
基础医学   682篇
口腔科学   303篇
临床医学   608篇
内科学   1506篇
皮肤病学   116篇
神经病学   439篇
特种医学   247篇
外国民族医学   7篇
外科学   1371篇
综合类   201篇
一般理论   3篇
预防医学   629篇
眼科学   171篇
药学   604篇
中国医学   59篇
肿瘤学   331篇
  2023年   62篇
  2022年   184篇
  2021年   277篇
  2020年   191篇
  2019年   236篇
  2018年   295篇
  2017年   180篇
  2016年   225篇
  2015年   213篇
  2014年   306篇
  2013年   404篇
  2012年   548篇
  2011年   531篇
  2010年   319篇
  2009年   278篇
  2008年   375篇
  2007年   440篇
  2006年   426篇
  2005年   420篇
  2004年   316篇
  2003年   294篇
  2002年   247篇
  2001年   113篇
  2000年   95篇
  1999年   88篇
  1998年   49篇
  1997年   39篇
  1996年   36篇
  1995年   31篇
  1994年   27篇
  1993年   24篇
  1992年   55篇
  1991年   54篇
  1990年   55篇
  1989年   51篇
  1988年   49篇
  1987年   61篇
  1986年   47篇
  1985年   37篇
  1984年   23篇
  1983年   23篇
  1979年   14篇
  1978年   14篇
  1977年   20篇
  1975年   15篇
  1974年   18篇
  1973年   20篇
  1972年   27篇
  1970年   19篇
  1969年   28篇
排序方式: 共有7997条查询结果,搜索用时 15 毫秒
1.
Xanthogranulomatous orchitis is an extremely rare inflammatory non-neoplastic destructive lesion of the testis. We report a 44-year-old man who presented with right scrotal swelling and two discharging sinuses. Testicular tumor markers were normal. Scrotal ultrasound showed heterogeneous testicular areas and irregular margin of the tunica. Surgical exploration revealed infected, unhealthy testicular tissue with necrosis and tumor-like lesion. Orchidectomy was done and histopathology showed xanthogranulomatous orchitis.  相似文献   
2.
We report a 24-year-old woman with an intramedullary conus ependymoma associated with holocord syringohydromyelia and syringobulbia. The tumor was removed and surgery for decompression of the syringohydromyelia was not considered at the first operation. In the follow-up examinations, MRI showed significant and steady improvement of syringohydromyelia. Symptoms associated with syringohydromyelia also disappeared. The cause of syringohydromyelia accompanying intradural spinal cord tumors appears to be either direct blockade of the central canal or secondary interruption of the central canal flow by compression of the perimedullary cerebrospinal fluid flow. As removal of the mass often corrects both these likely causes of the syringohydromyelia, no additional treatment for the drainage of the hydromyelia cavity syrinx is usually necessary.  相似文献   
3.
Summary The paucity of information on the effect of long-term high-dose salmon calcitonin administration on normal bone mineral metabolism and histology prompted an investigation of the influence of high-dose synthetic calcitonin in the rat. Serum ionized calcium, osteocalcin or BGP (bone gla protein), and immunoreactive PTH were measured serially during calcitonin administration and bone histomorphometry analyzed at 6 weeks (after sacrifice). Daily injections of salmon calcitonin, 0.4 IU/100 g (group B) and 2 IU/100 g (group C), resulted in significant hypocalcemia at 4 hours for both experimental groups (P<0.004). Serium iPTH was significantly higher over the study period for both groups administered calcitonin. Serum BGP levels were significantly lower than controls during the study in group C (P<0.002) and to a lesser extent in group B (P<0.05). In group C, bone histomorphometry revealed increased resorption (onteoclast count), decreased trabecular bone volume, and decreased double-labeled tetracycline surface (bone formation). In group B an increase in osteoclast count but no alteration in bone formation was observed. To assess the role of PTH in the above findings, high-dose calcitonin was administered to parathyroidectomized rats. All of the above changes in bone histomorphometry were not observed in this group of animals. In conclusion, high doses of calcitonin promote hypocalcemia, secondary hyperparathyroidism, and osteoclastosis in the normal rat in a dose-dependent manner with very high-dose calcitonin impairing bone formation.  相似文献   
4.
Partially edentulous patients with alveolar defects contraindicating implant placement were treated with bone grafts obtained from the mandibular symphysis. Complications encountered were minor and uneventful. Evaluation 4 months after surgery revealed minimal graft resorption, thus implant placement was possible in all potential sites. Advantages of the symphysis graft include easy access, availability of greater quantities of bone over other intraoral donor sites, low morbidity, no hospitalization, minimal discomfort, no alteration in ambulation, and no cutaneous scar. Compared with other bone regenerative methods for implant placement, a superior quality of bone was found and a shorter healing period is required. Results of this preliminary clinical investigation demonstrate that chin grafts offer a viable alternative for reconstruction of alveolar defects prior to dental implant placement.  相似文献   
5.
Renal transplant recipients treated with cyclosporine (CS) have been reported to be at increased risk of thrombotic complications. The present study was intended to examine the blood coagulation, fibrinolytic, and inhibitory systems in such patients. Eight transplant recipients on maintenance immunosuppression with CS and prednisone were studied. Five transplant recipients maintained on azathioprine (AZA) and prednisone and 32 normal volunteers served as controls. Plasma antigen concentrations and/or activities of various proteins in the above pathways were measured. Both the CS and AZA groups exhibited significant elevations of factor IX activity, von Willebrand factor (vWF), D-dimer, protein C and tissue type plasminogen activator (t-PA) levels when compared with the normal controls. In addition, CS group showed a significant elevation of alpha 2-macroglobulin activity and AZA group showed a significant reduction in factor XII activity when compared with the normal controls. Comparison of data from CS and AZA groups revealed higher factor XII activity and vWF concentration in the former group. In conclusion, transplant recipients treated with long-term cyclosporine and prednisone exhibited significant elevation of plasma vWF, D-dimer and protein C concentrations. In addition, both CS and AZA-treated transplant recipients showed increased plasma concentrations of D-dimer and t-PA. The latter observations suggest in vivo thrombin generation, fibrin formation and degradation.  相似文献   
6.
1. Phospholipase A2 (PLA2) cleaves phospholipids to produce a lyso-phospholipid and free fatty acid and, in view of the biological activity of the products, PLA2 may play a role in many disease states. Lyso-phospholipids and free arachidonic acid increase in ischaemic myocardium, indicating that ischaemia activates the enzyme. 2. Plasma PLA2 activity was measured in patients with acute myocardial infarction, based on the release of labelled arachidonic acid from Escherichia coli cell membrane. Fourteen males (peak serum creatine phosphokinase (CK) above twice upper normal) were studied on day 1 (within 6 h of chest pain onset), days 2-4, and days 6-9. Normal age matched males (n = 13) were also studied. 3. Plasma PLA2 in patients with uncomplicated myocardial infarction (n = 12) was, initially, 1.14 +/- 0.10 (s.e.m.) nmol/min per mL plasma, similar to that in the normal group (1.52 +/- 0.14). On days 2-4, PLA2 activity increased to 1.94 +/- 0.18 (P less than 0.001) and this activity was correlated with the earlier peak CK level (P less than 0.02). On days 6-9, PLA2 activity was 1.49 +/- 0.13 while in two patients who developed complications and underwent open-heart surgery between the last two measurements, there were further increases to 4.22 and 4.04 nmol/min per mL. 4. The increase in plasma PLA2 in uncomplicated myocardial infarction is likely to be due to release from the damaged myocardium; whether it contributes to pathophysiology is uncertain.  相似文献   
7.
An entomological survey was carried out during 1986 in ten provinces of Syria representative of the main natural areas of this country. 932 sandflies were caught with aspirators in domestic resting sites. Captures are analysed for each species.  相似文献   
8.
There are significant variations among countries in the incidence of brain abscess. We report here 26 cases of brain abscess treated at the Neurosurgery Department of King Faisal University and Dammam Central Hospital Saudi Arabia over a six year period (1982–1988). This is 2.3% of total admissions to the two neurosurgery departments serving a population of approximately 1.2 million in the same period.Young males were most often affected (M/F ratio 3.3:1; 31% were less than 15 years old, 46% aged between 15–39 years, and 23% older than 40 years). Streptococcus was found to be the most common microorganism (38.4%). Mixed infection was seen in 15.3%, and sterile abscesses were found in 11.5% of the patients after aerobic and anaerobic cultures of the pus. Chronic otitis media and paranasal sinusitis predisposed the patients to abscess formation in 57.6% of the cases. The temporo-parietal area was the commonest site. Epilepsy was a complication in 30.7% of our patients, and the mortality rate was 15.3%.  相似文献   
9.
The carotid artery stump pressure has been used as a criterion for selective placement of a shunt during carotid endarterectomy. The purpose of our study was to correlate the carotid stump pressure with the presence or absence of a palpable pulse in the carotid stump. One hundred twenty-two consecutive patients undergoing carotid endarterectomy under general anesthesia were checked for a palpable pulse in the internal carotid stump with subsequent measurements of the stump pressure. Of these patients, 88 had a palpable pulse and a pressure greater than or equal to 44 mmHg. The remaining 34 had a absent pulse and a stump pressure of 40 mmHg or less. Shunts were not used in those patients with a palpable pulse and no history of previous stroke or contralateral carotid occlusion. There were no serious neurological complications. We conclude that the presence of a palpable pulse in the carotid stump is a sufficient criterion for performing carotid endarterectomy without a shunt in those patients with no previous history of stroke or contralateral carotid occlusion.  相似文献   
10.
PURPOSE: To report the first successful endovascular repair of a non-aneurysmal aortic rupture due to periaortic tumour regression. CASE REPORT: A 58-year-old man developed spontaneous infrarenal aortic rupture following chemotherapy which led to regression of a periaortic mesothelioma that had been diagnosed during explorative laparotomy 11 months earlier. Stent-graft placement was performed with intentional conversion of a bifurcated (Zenith, COOK) into an aorto-uni-iliac system. No complications were encountered during a 40 months follow-up. CONCLUSION: Endovascular repair should be considered as a treatment option in non-aneurysmal aortic rupture.  相似文献   
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