全文获取类型
收费全文 | 39134篇 |
免费 | 1540篇 |
国内免费 | 214篇 |
专业分类
耳鼻咽喉 | 354篇 |
儿科学 | 553篇 |
妇产科学 | 424篇 |
基础医学 | 5068篇 |
口腔科学 | 1108篇 |
临床医学 | 2530篇 |
内科学 | 9602篇 |
皮肤病学 | 976篇 |
神经病学 | 2699篇 |
特种医学 | 1441篇 |
外科学 | 6534篇 |
综合类 | 206篇 |
一般理论 | 1篇 |
预防医学 | 1223篇 |
眼科学 | 746篇 |
药学 | 2931篇 |
中国医学 | 49篇 |
肿瘤学 | 4443篇 |
出版年
2023年 | 198篇 |
2022年 | 390篇 |
2021年 | 733篇 |
2020年 | 472篇 |
2019年 | 563篇 |
2018年 | 697篇 |
2017年 | 611篇 |
2016年 | 650篇 |
2015年 | 705篇 |
2014年 | 932篇 |
2013年 | 1165篇 |
2012年 | 1781篇 |
2011年 | 1964篇 |
2010年 | 1130篇 |
2009年 | 1001篇 |
2008年 | 1713篇 |
2007年 | 1772篇 |
2006年 | 1791篇 |
2005年 | 1829篇 |
2004年 | 1745篇 |
2003年 | 1744篇 |
2002年 | 1698篇 |
2001年 | 1353篇 |
2000年 | 1370篇 |
1999年 | 1271篇 |
1998年 | 482篇 |
1997年 | 405篇 |
1996年 | 378篇 |
1995年 | 355篇 |
1994年 | 306篇 |
1993年 | 297篇 |
1992年 | 869篇 |
1991年 | 754篇 |
1990年 | 757篇 |
1989年 | 732篇 |
1988年 | 736篇 |
1987年 | 648篇 |
1986年 | 632篇 |
1985年 | 615篇 |
1984年 | 408篇 |
1983年 | 334篇 |
1982年 | 161篇 |
1980年 | 149篇 |
1979年 | 328篇 |
1978年 | 212篇 |
1977年 | 156篇 |
1975年 | 156篇 |
1974年 | 213篇 |
1973年 | 152篇 |
1972年 | 167篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
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
73.
N Abe A Kashiwagi Y Kida Y Sigeta A Hattori M Yamamoto M Kato 《Nihon Ronen Igakkai zasshi. Japanese journal of geriatrics》1991,28(4):530-535
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
74.
75.
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
76.
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
77.
Ultracytochemical investigation of calcium-activated adenosine triphosphatase (Ca++-ATPase) in chick tibia 总被引:4,自引:0,他引:4
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
78.
The clinical usefulness of 67Ga-DFO-DAS-fibrinogen, a newly developed thrombus imaging agent, was evaluated. Fifteen cases were given 2 mCi of 67Ga-DFO-DAS-fibrinogen and images were obtained up to 96 hours after injection. Abnormal accumulation of 67Ga-DFO-DAS-fibrinogen was imaged in seven cases with either venous or arterial thrombi, and no side effects were noted. These results suggested that 67Ga-DFO-DAS-fibrinogen might be a promising agent for thrombus imaging. 相似文献
79.
N Aoki T Kitahara T Fukui J R Beck K Soma W Yamamoto I Kamae T Ohwada 《Medical decision making》1998,18(4):357-364
The purpose of this study was to analyze the management of individual patients with unruptured intracranial aneurysms (UN-ANs) using a decision-analytic approach. Transition probabilities among Glasgow Outcome Scale (GOS) categories were estimated from the published literature and data from patients who had been treated at Kitasato University Hospital. Utilities were obtained from 140 health providers based principally on the GOS. Baseline analysis for a healthy 40-year-old man with an anterior UN-AN less than 10 mm in diameter showed that the quality-adjusted life expectancies for preventive operation and follow-up were 15.34 and 14.66 years, respectively. For a follow-up strategy to be preferred, the annual rupture rate had to be as low as 0.9%. These results were sustained through extensive sensitivity analysis. The results support preventive operation for UN-ANs, and identify problems that can be clarified with a well-designed stratified clinical trial. 相似文献
80.
A cerebral type of Lewy body disease (LBD) is proposed. Lewy body disease was split formerly into three types: brainstem type, transitional type and diffuse type. The diffuse type is now called diffuse Lewy body disease (DLBD). These three types are characterized pathologically by the presence of a large number of Lewy bodies in the CNS. In the brainstem type, Lewy bodies are numerous in the brainstem and diencephalon nuclei, and in DLBD, a vast number are present not only in these nuclei but also in the cerebral cortex and amygdala. In the cerebral type of LBD, as many Lewy bodies are found in the cerebral cortex and in the amygdala as there are in DLBD, but only rarely are they present in the brainstem and diencephalon nuclei. Thus, this type of LBD is different from other types in that it has no parkinson pathology. Therefore, parkinsonism fails to occur throughout the whole clinical course of this disease. The existence of a cerebral type of LBD suggests that Lewy bodies occur in the cerebral cortex earlier than in the brainstem nuclei and that cortical Lewy bodies appear even when the mesocortical dopaminergic system is intact. In addition, this might explain why dementia frequently precedes parkinsonism in DLBD. 相似文献