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   1357066篇
  免费   97866篇
  国内免费   2931篇
耳鼻咽喉   19998篇
儿科学   41079篇
妇产科学   39212篇
基础医学   189971篇
口腔科学   40256篇
临床医学   115687篇
内科学   266312篇
皮肤病学   30575篇
神经病学   108597篇
特种医学   54489篇
外国民族医学   435篇
外科学   211161篇
综合类   31574篇
现状与发展   6篇
一般理论   467篇
预防医学   94656篇
眼科学   31781篇
药学   101819篇
  5篇
中国医学   3018篇
肿瘤学   76765篇
  2018年   12106篇
  2015年   12225篇
  2014年   17214篇
  2013年   26060篇
  2012年   34034篇
  2011年   36030篇
  2010年   21390篇
  2009年   20694篇
  2008年   34580篇
  2007年   37778篇
  2006年   38344篇
  2005年   37029篇
  2004年   36116篇
  2003年   34943篇
  2002年   34417篇
  2001年   64363篇
  2000年   66094篇
  1999年   55998篇
  1998年   14891篇
  1997年   13683篇
  1996年   13125篇
  1995年   12413篇
  1994年   11641篇
  1992年   43291篇
  1991年   41827篇
  1990年   41079篇
  1989年   40026篇
  1988年   37414篇
  1987年   36838篇
  1986年   35343篇
  1985年   33520篇
  1984年   25162篇
  1983年   21388篇
  1982年   12889篇
  1981年   11768篇
  1980年   10960篇
  1979年   24240篇
  1978年   17304篇
  1977年   15048篇
  1976年   13575篇
  1975年   15447篇
  1974年   18303篇
  1973年   17760篇
  1972年   16984篇
  1971年   15890篇
  1970年   15068篇
  1969年   14480篇
  1968年   13571篇
  1967年   12121篇
  1966年   11357篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
AIM: The complication of nerve injury after greater saphenous vein stripping for varicosity is subjective, and a method for objective evaluation has never been established. The aim of this study was to evaluate postoperative sensory changes by quantitative assessment of current perception threshold (CPT), and to clarify the relation between CPT and symptoms. PATIENTS AND METHODS: Between January 2003 and August 2005, 27 limbs in 18 patients were enrolled. Quantitative sensory function was determined through CPT using a Neurometer (Neurotron, Inc., USA), with which saphenous nerve neural fiber selective minimum sensing values against three electrical stimuli (2000, 250, 5 Hz) were measured. CPT measurements were scheduled on the day before the operation, and 2-7 days, 1, 3, and 6 months after the operation. RESULTS: An increase in CPT value of more than 20% or decrease to below 50% compared to the preoperative value with at least two stimuli was defined as CPT abnormality. Subjective symptoms were observed in 13 limbs in the early postoperative period, and 10 limbs showed CPT abnormality. In 6 limbs with a CPT increase over 20% with all three stimuli, neurological symptoms continued for 6 months. CONCLUSIONS: CPT evaluation provides an objective indication of neurological symptoms in the lower limb following varicose vein surgery.  相似文献   
993.
Extubation difficulties after long-term endotracheal intubation in neonates and infants require immediate re-intubation with a somewhat thinner endotracheal tube, continuation of long-term intubation for another 7–14 days with antibiotic and antiphlogistic therapy including antireflux treatment as well as a subtile endoscopic examination. A tracheostomy is not indicated before several attempts of extubation have failed. An anterior cricoid split should be indicated with great care and in premature neonates only. In manifest cicatrical stenoses, subtile endoscopic diagnostics are an essential prerequisite for the choice of surgical method and time of surgery. In rather mild stenoses (grade II), laryngotracheal reconstruction (LTR) with anterior wall cartilage grafting is presently regarded as method of choice. For subglottic stenoses of higher degrees (grade III and IV), partial cricotracheal resection (PCTR) is felt to be the most successful procedure. For all scarred stenoses involving the glottic level, LTR with posterior and anterior wall cartilage grafting appears to be the only suitable treatment. LTR with anterior wall grafting only as well as the PCTR can be performed as a single stage procedure with postoperative long-term intubation on an intensive care unit for one or more days. LTR with posterior and anterior wall grafting requires long-term stenting for several weeks or months depending upon the individual condition. For long-term stenting, our so-called double-tube-technique using a modified Montgomery T silicon tube together with a perforated tracheal cannula has proved to be the safest and least irksome technique.  相似文献   
994.
Background Diagnosis of brainstem lesions in children based on magnetic resonance imaging alone is a challenging problem. Magnetic resonance spectroscopy (MRS) is a noninvasive technique for spatial characterization of biochemical markers in tissues and gives information regarding cell membrane proliferation, neuronal damage, and energy metabolism. Methods We measured the concentrations of biochemical markers in five children with brainstem lesions and evaluated their potential diagnostic significance. Images and spectra were acquired on a 1.5-T imager. The concentrations of N-acetylaspartate, tetramethylamines (e.g., choline), creatine, phosphocreatine, lactate, and lipids were measured within lesions located at the brainstem using Point-resolved spectroscopy sequences. Results Diagnosis based on localized proton spectroscopy included brainstem glioma, brainstem encephalitis, demyelination, dysmyelination secondary to neurofibromatosis type 1 (NF 1), and possible infection or radiation necrosis. In all but one patient, diagnosis was confirmed by biopsy or by clinical follow-up. Conclusions This small sample of patients suggests that MRS is important in the differential diagnosis between proliferative and nonproliferative lesions in patients without neurofibromatosis. Unfortunately, in cases of NF 1, MRS can have a rather misdiagnosis role.  相似文献   
995.
The authors present a case of amyloid infiltration involving the trigeminal nerve that mimicked a malignant cavernous sinus tumor with perineural tumor infiltration. A 64-year-old man presented with trigeminal nerve numbness. Imaging revealed a plaque-like enhancing lesion along the right lateral cavernous sinus extending anteriorly into Meckel's cave and involving the proximal V2 and V3 branches of the trigeminal nerve. The patient underwent an extradural frontotemporal craniotomy with middle fossa exposure of the cavernous sinus to diagnose and treat the presumed malignant cavernous sinus tumor. A reddish mass involving the lateral dural wall of the cavernous sinus was resected. The gasserian ganglion, V2, and V3, the latter of which was biopsied, were enlarged. Permanent histopathological studies showed microscopic eosinophilic, amorphous material, which stained positive for Congo red, and an absence of neoplastic cells. The final diagnosis was amyloidoma. Thus, amyloidomas can involve the trigeminal nerve or ganglia and should be considered in the differential diagnosis of a cavernous sinus lesion mimicking a tumor. Patients may have symptomatic improvement of trigeminal neuropathy with resection of the amyloidoma outside the nerve capsule that is compressing the nerve, while resection of the lesion from within the capsule may result in permanent trigeminal nerve dysfunction.  相似文献   
996.
BACKGROUND: Although many histopathologic factors in squamous cell carcinoma of the tongue predict the prognosis, the major predictive factors have not been identified clearly. This study analyzed the prognostic value of the histologic grade at the deep invasive front of tongue squamous cell carcinoma. METHODS: The clinicopathologic features of 124 consecutive patients seen between January 1985 and December 1999 with previously untreated squamous cell carcinoma of the tongue were reviewed. Their mean age was 58.5 years (range: 23-90) and the male-female ratio was 1.8: 1 (79 men and 45 women). There were 41, 40, 30, and 13 cases at stage I to stage IV, respectively. The clinicopathologic factors, especially the histologic grade at the deep invasive front (invasive front grade, IFG), were analyzed to determine factors predicting prognosis. RESULTS: The 5-year disease-free survival rate of the patients treated with curative aim only was 66.7%. Clinicopathologic factors significantly associated with the prognosis were T classification, tumor size, stage classification, tumor depth, macroscopic appearance, cervical lymph node metastasis (nodal metastasis), microvascular invasion, and IFG. In a multivariate analysis, patients with tumor depth >/=4 mm, IFG >/=8 points, and nodal metastasis had a reduced disease-free survival and IFG >/=11 points had a predictive value for nodal metastasis (odds ratio: 7.34; P = 0.0019). CONCLUSION: This study found that a high IFG malignancy score had a high prognostic value for squamous cell carcinoma of the tongue.  相似文献   
997.
Ultrasonotomograms of 22 kidneys were obtained in 11 patients with renal-acute renal failure (renal-ARF). The underlying diseases of renal-ARF were acute tubular necrosis in 8 patients and acute on-set chronic glomerulonephritis in 3 patients. They were treated by hemodialysis in 10 patients and intermittent peritoneal dialysis in 1 patient. Ultrasonic measurement of the size of kidneys revealed that the thickness (anterior-posterior diameter) and the ratio of thickness to length (T/L) were greater in patients with ARF than in those with chronic renal failure and normal renal function. The patients with a low value of T/L (under 0.60) had a significantly greater urine volume than those with high a value of T/L (0.60 or more). The sonographic features of renal-ARF kidneys were marked increase in parenchymal echogenicity and appearance of hypoechoic swollen renal pyramids with sharpness of the corticomedullary border. In the course of ARF, these sonographic changes gradually disappeared when the patients had recovered from ARF. However, the prognosis was poor in patients with severer sonographic findings. We believe that repeated ultrasonic examination of the kidneys in patients with renal-ARF is useful for not only differential diagnosis of post-renal urinary obstruction but evaluating the course of ARF.  相似文献   
998.
999.
Artificial dopamine agonists are widely employed for the treatment of idiopathic parkinsonism. Pleuropulmonary disease has previously been reported to occur with the use of bromocriptine and mesulergine. We report similar adverse effects induced by the newer agonists lisuride and cabergoline. All these agents are tetracyclic ergot derivatives. This suggests a causal link between ergot-derived dopamine agonists and pleuropulmonary disease.  相似文献   
1000.
Postencephalitic acquired Tourette-like syndrome in a child.   总被引:1,自引:0,他引:1  
R S Northam  H S Singer 《Neurology》1991,41(4):592-593
We report a 6-year-old girl who developed a Tourette-like syndrome following presumed herpes encephalitis. This case suggests that tics can be acquired in childhood and may be associated with lesions involving basal ganglia or limbic circuitry.  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