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   36648篇
  免费   1917篇
  国内免费   175篇
耳鼻咽喉   321篇
儿科学   491篇
妇产科学   371篇
基础医学   4817篇
口腔科学   1084篇
临床医学   2330篇
内科学   9086篇
皮肤病学   875篇
神经病学   2617篇
特种医学   1477篇
外科学   6435篇
综合类   172篇
一般理论   1篇
预防医学   1087篇
眼科学   660篇
药学   2644篇
中国医学   50篇
肿瘤学   4222篇
  2023年   180篇
  2022年   393篇
  2021年   710篇
  2020年   402篇
  2019年   497篇
  2018年   641篇
  2017年   554篇
  2016年   637篇
  2015年   689篇
  2014年   871篇
  2013年   1098篇
  2012年   1653篇
  2011年   1811篇
  2010年   1050篇
  2009年   937篇
  2008年   1597篇
  2007年   1605篇
  2006年   1650篇
  2005年   1735篇
  2004年   1646篇
  2003年   1660篇
  2002年   1544篇
  2001年   1346篇
  2000年   1368篇
  1999年   1258篇
  1998年   460篇
  1997年   395篇
  1996年   361篇
  1995年   341篇
  1994年   275篇
  1993年   282篇
  1992年   849篇
  1991年   744篇
  1990年   746篇
  1989年   725篇
  1988年   722篇
  1987年   631篇
  1986年   624篇
  1985年   605篇
  1984年   402篇
  1983年   334篇
  1982年   152篇
  1979年   321篇
  1978年   206篇
  1977年   152篇
  1975年   150篇
  1974年   214篇
  1973年   151篇
  1972年   167篇
  1971年   148篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
During a 12-month period ending on November 30, 1988, data were collected on 2468 pediatric patients with wheezing who visited a pediatric ED. Cohort characteristics included: sex (64% male, 36% female), history of prematurity (12%), evidence of concurrent infection (82%), taking theophylline (35%), taking beta adrenergics (60%), taking cromolyn (6%), and taking corticosteroids (4%). The hospitalization rate was 10.5%. Seasonal variations, weather, air quality, and infections appeared to have significant effects on the daily variation of wheezing exacerbations. Initial oxygen saturation (OSAT) correlated with disease severity as measured by hospitalization risk and the number of bronchodilator treatments required in the ED. A suggestion for categorizing the treatment of asthma based on past history is proposed. Using this system in conjunction with pulse oximetry, wheezing severity and appropriate therapy can be more objectively determined.  相似文献   
102.
Recently, plasma fructosamine concentration has been used as an indication of mean plasma glucose level preceding at last 1 to 2 weeks. In the present study, to characterize the clinical significance and problems of plasma fructosamine concentration in aged subjects (greater than or equal to 65 yrs), we determined plasma fructosamine concentration as well as serum albumin, total protein, HbA1, AbA1c and fasting plasma glucose concentrations in 81 (less than 65 yrs) non-diabetic subjects (group A), 161 aged (greater than or equal to 65 yrs) non-diabetic subjects and 26 aged diabetics (group D). Aged non-diabetic subjects were further classified into 75 subjects with good ADL (group B) and 86 with poor ADL (group C). The normal limit of plasma fructosamine concentration (mean +/- 2SD) in group A was 24% higher (3.1 mmol/l) than that in group B (2.5 mmol/l) but the plasma fructosamine/serum albumin ratio (F/ALB) was similar in these two groups. Plasma fructosamine correlated negatively (p less than 0.01) with age. This aging effect was explained by the reduced serum albumin in aged subjects. However, in group C, reduced plasma albumin was not associated with reduced plasma fructosamine. Plasma fructosamine corrected by albumin (F/ALB) is a useful parameter of blood glucose control in aged subjects. In aged subjects with poor ADL, HbA1, HbA1c and plasma glucose should be determined with fructosamine.  相似文献   
103.
p = 0.0007) and tumor necrosis (TN) (HMC: p = 0.0050). Univariate analysis showed that AMC or HMC was a statistically significant predictor of overall survival in all patients ( p = 0.0086 and p = 0.0307, respectively). Multivariate analysis showed that AMC was an independent predictor of node status when we fitted a model with node status, BVI, and either AMC or HMC; but HMC was not independent. However, when we fitted a model including all 11 of the other indicators and AMC or HMC, the node status, HG, and LI were independent predictors, but AMC and HMC were not. Although AMC was a better method than HMC for evaluating angiogenesis, we cannot confirm angiogenesis as a significant independent prognostic factor associated with long-term survival in Japanese breast cancer patients.  相似文献   
104.
105.
We reviewed the radiographs of 25 hips of 20 patients who had received revisions of the acetabular components of total hip replacement supplemented by allograft for bone defects. Bone defects in 20 hips (80%) were classified into type D (cranio-central defect) according to Itoman's classification. In eight, sockets were installed directly on the allografts (group A). A metallic supporting device was used for reinforcing the grafts in 17 hips (group B). The position of the acetabular socket was measured on a radiograph, taken immediately after revision surgery and again at the latest follow-up. Using a MEM template, cranial and central migrations were determined. Mean cranial migration in hips of group A was 3.6 mm. Group B was 0.2 mm. Maintenance of thickness of the allografts was 60.6% in the cranial region and 75% in the central in group A. In the hips of group B, however, almost 100% of the initial thickness was maintained cranially and centrally. Allograft reconstruction of acetabular bone defect in revision total hip replacement is a beneficial procedure. The remaining pelvic bone is usually in poor condition, therefore, it is necessary to ensure primary fixation by the metallic supporting device.  相似文献   
106.
A case of 'low tension glaucoma' with primary empty sella is reported. The visual field defect and optic disc change were characteristic of glaucoma. The intraocular pressure was within normal limits. X-ray examination and the metrizamide-CF procedures revealed a primary empty sella. The coexistence of 'low tension glaucoma' and empty sella is discussed.  相似文献   
107.
108.
A 74-year-old woman suffered from progressive muscle atrophy and weakness of her arms since she was seventy two years old. Before referral to our department, she was diagnosed as having cervical spondylotic myeloradiculopathy and received spinal fusion. Though spinal decompression was successful, muscle weakness of her upper limbs were progressive even after the surgery. On admission, neurological examinations revealed marked atrophy and weakness of her bilateral upper limbs with absent deep tendon reflexes showing man-in-the-barrel syndrome. Her lower extremities had normal muscle strength, but fasciculations were seen in her all four limbs. Electrophysiologically, motor nerve conduction velocity was almost normal but the amplitude was remarkably decreased, conduction block was not detected, and electromyography showed neurogenic patterns on her all extremities. Spinal progressive musclar atrophy (SPMA) accompanied with Sj?gren's syndrome was the likely diagnosis. Because 50 kDa anti-neuronal antibodies were found in her serum, we assumed that anterior horn cells were impaired by an autoimmune mechanism. Thus we treated her with corticosteroid pulse therapy, plasma exchange (PE) and intravenous immunoglobulin infusion therapy (IVIG). Although steroid pulse therapy only had a minimal effect, PE and IVIG promoted a remarkable improvement on her weakness, and the effect lasted for about three months. This is the first case of SPMA with Sj?gren's syndrome which showed good response to PE and IVIG in the early course of the disease. We considered that some SPMA-like motor neuron syndrome accompanied with autoimmune features may require immunomodulating therapies.  相似文献   
109.
Thirty-one prolonged coma patients, who continued in a comatose state for at least 2 months, were classified electrophysiologically employing EEG, a compressed spectral array of continuous EEG frequency analysis, BSR, SEP and SSEP. The prognoses of long-term follow-up (at least 8 months) in these patients were compared with the results of such electrophysiological analysis and with the neurological gradings of the prolonged coma patients. In the continuous EEG frequency analysis, 22 cases were classified as having a changeable spectrogram, nine cases as having a slow monotonous spectrogram, and no cases as having a borderline spectrogram. We also classified the changeable spectrograms into the following three patterns: no desynchronization, slight desynchronization, and desynchronization. The nine cases with a slow monotonous spectrogram revealed severe damage of the brain stem and cerebral function with multimodality evoked potentials, and most of these cases could not survive without assisted respiration. The 22 cases with a changeable spectrogram had mild damage of the brain stem and cerebral function with multimodality evoked potentials, and these cases were identical with a persistent vegetative state. Three of the cases showed a changeable spectrogram that revealed a desynchronization pattern, normal BSR and normal N20 of SEP and SSEP, recovered spontaneously from the persistent vegetative state within 6 months after electrophysiological evaluation. We conclude that not only a neurological but also an electrophysiological classification is necessary to evaluate the brain function and prognosis of prolonged coma.  相似文献   
110.
The ultrastructural distribution of Ca++-ATPase in bone cells of growing chick tibia was investigated by a cytochemical method in order to gain insight into possible sites of calcium ion translocation. Both osteoclasts and osteoblasts showed a polar distribution of reaction product along the plasma membrane. In osteoclasts, enzymatic activity occurred along the portion of the plasma membrane facing the marrow but not along the ruffled border or clear zone. The reaction product in these cells was due solely to Ca++-ATPase action. In osteoblasts, the plasma membrane facing away from bone (apical and lateral membrane) was very intensely stained, whereas the basal membrane was unstained. The reaction product in these cells appeared to be the result of both Ca++-ATPase and Ca++,Mg++-ATPase. In osteocytes, no plasma membrane staining was detectable. Mitochondrial staining in all three types of cells was more sensitive to fixation than was the plasma membrane enzyme, suggesting that mitochondrial and plasma membrane Ca++-ATPases are chemically distinct, as biochemical studies have shown. In general, mitochondria in osteoclasts stained more intensely than those in osteoblasts or osteocytes. Mitochondrial and vesicular sites of activity may be related to intracellular calcium storage, whereas calcium ATPases of the plasma membrane are presumed to be involved in calcium efflux from the cells. Calcitonin treatment did not alter the enzymatic distribution or intensity in osteoclasts. The striking polar distribution of both osteoclast and osteoblast plasma-membrane activity suggests that directional calcium pumping by these cells may be of importance in bone-forming and bone-resorbing mechanisms.  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