全文获取类型
收费全文 | 15128篇 |
免费 | 983篇 |
国内免费 | 186篇 |
专业分类
耳鼻咽喉 | 218篇 |
儿科学 | 331篇 |
妇产科学 | 733篇 |
基础医学 | 1931篇 |
口腔科学 | 261篇 |
临床医学 | 1585篇 |
内科学 | 3202篇 |
皮肤病学 | 372篇 |
神经病学 | 934篇 |
特种医学 | 472篇 |
外科学 | 2319篇 |
综合类 | 419篇 |
现状与发展 | 2篇 |
一般理论 | 3篇 |
预防医学 | 761篇 |
眼科学 | 286篇 |
药学 | 1083篇 |
中国医学 | 102篇 |
肿瘤学 | 1283篇 |
出版年
2023年 | 79篇 |
2022年 | 236篇 |
2021年 | 435篇 |
2020年 | 220篇 |
2019年 | 329篇 |
2018年 | 420篇 |
2017年 | 290篇 |
2016年 | 293篇 |
2015年 | 458篇 |
2014年 | 585篇 |
2013年 | 731篇 |
2012年 | 1106篇 |
2011年 | 1091篇 |
2010年 | 702篇 |
2009年 | 571篇 |
2008年 | 875篇 |
2007年 | 887篇 |
2006年 | 804篇 |
2005年 | 822篇 |
2004年 | 700篇 |
2003年 | 578篇 |
2002年 | 539篇 |
2001年 | 471篇 |
2000年 | 414篇 |
1999年 | 349篇 |
1998年 | 128篇 |
1997年 | 102篇 |
1996年 | 84篇 |
1995年 | 68篇 |
1994年 | 65篇 |
1993年 | 44篇 |
1992年 | 179篇 |
1991年 | 168篇 |
1990年 | 145篇 |
1989年 | 120篇 |
1988年 | 107篇 |
1987年 | 122篇 |
1986年 | 100篇 |
1985年 | 83篇 |
1984年 | 75篇 |
1983年 | 58篇 |
1980年 | 38篇 |
1979年 | 57篇 |
1978年 | 49篇 |
1977年 | 42篇 |
1976年 | 39篇 |
1975年 | 38篇 |
1974年 | 47篇 |
1972年 | 59篇 |
1971年 | 35篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Diffuse pulmonary hemorrhage leading to death is a syndrome which may develop in leptospirosis, but its pathophysiology is not well documented. We report an autopsy case of leptospirosis. A healthy 41-year-old man presented with low back myalgia, dry cough and fever for 4 days and a normal chest X-ray on admission. Acute respiratory failure developed hours later. Profuse bloody fluid appeared in the endotracheal tube immediately after intubation. Chest X-ray showed whiteness across all lung fields. He died of persistent shock 16 h after the onset of acute respiratory failure. Autopsy revealed diffuse pulmonary hemorrhage with hyaline-membrane formation, myocarditis, interstitial nephritis and hepatitis. Silver stain of lung and kidney tissue demonstrated leptospires. Immunohistochemical staining showed inducible nitric oxide synthase in alveolar macrophages. Immunofluorescein staining showed immunoglobulin in alveolar septum and alveolar space. This case suggests that hemorrhagic diffuse alveolar damage with persistent shock is related to over-production of nitric oxide and immunoglobulin deposition in fatal leptospirosis. 相似文献
42.
James A. Case Bai Ling Hsu Timothy M. Bateman S. James Cullom 《Journal of nuclear cardiology》2007,14(3):324-333
Background High-quality attenuation maps are critical for attenuation correction of myocardial perfusion single photon emission computed
tomography studies. The filtered backprojection (FBP) approach can introduce errors, especially with low-count transmission
data. We present a new method for attenuation map reconstruction and examine its performance in phantom and patient data.
Methods and Results The Bayesian iterative transmission gradient algorithm incorporates a spatially varying gamma prior function that preferentially
weights estimated attenuation coefficients toward the soft-tissue value while allowing data-driven solutions for lung and
bone regions. The performance with attenuation-corrected technetium 99m sestamibi clinical images was evaluated in phantom
studies and in 50 low-likelihood patients grouped by body mass index (BMI). The algorithm converged in 15 iterations in the
phantom studies. For the clinical studies, soft-tissue estimates had significantly greater uniformity of mediastinal coefficients
(mean SD, 0.005 cm−1 vs 0.011 cm−1; P<.0001). The accuracy and uniformity of the Bayesian iterative transmission gradient algorithm were independent of BMI, whereas
both declined at higher BMI values with FBP. Attenuation-corrected perfusion images showed improvement in myocardial wall
variability (4.8% to 4.1%, P=.02) for all BMI groups with the new method compared with FBP.
Conclusion This new method for attenuation map reconstruction provides rapidly converging and accurate attenuation maps over a wide spectrum
of patient BMI values and significantly improves attenuation-corrected perfusion images. 相似文献
43.
Ming-Shian Tsai Wen-Hsi Lin Wen-Ming Hsu Hong-Shiee Lai Po-Huang Lee Wei-Jao Chen 《Journal of gastrointestinal surgery》2008,12(12):2191-2195
Background/aims Surgical resection of choledochal cysts (CC) has become standard treatment. However, surgery is not universally recommended
in early infancy and/or asymptomatic patients. In order to investigate the optimal timing of CC excision, we analyzed clinicopathological
data and surgical results from different age groups.
Material and methods This retrospective review included 107 patients (77 females, 30 males) who underwent CC resection at the National Taiwan University
Hospital between January 1988 and December 2005. Patient demographic, clinical, and surgical data were collected and analyzed.
Results The patients were divided into three groups according to age at the time of surgery: <1 year old (group I, n = 26), 1−16 years old (group II, n = 48), and >16 years old (group III, n = 33). About two thirds of the patients in group I had jaundice, while abdominal pain related to inflammation was the commonest
symptom in groups II and III. Group I suffered significantly fewer surgical complications and less severe liver fibrosis than
groups II or III.
Conclusion CC surgery in infancy and in asymptomatic patients is safe and may prevent the complications of this condition. The results
support a recommendation for early excision. 相似文献
44.
45.
Tadpole and adult Xenopus, manipulated to be of comparable size, exhibited stagespecific
antibody expression. The production of adult-type higher-affinity anti-DNP
antibodies proved to be independent of the age and size of the individual and is
concomitant with the completion of metamorphosis. The appearance of new antibody
specificities at such a time suggests that their expression occurs with the cell turnover
and renewal during a period of morphological changes. 相似文献
46.
Intestinal schistosomiasis japonica: CT-pathologic correlation 总被引:1,自引:0,他引:1
Lee RC; Chiang JH; Chou YH; Rubesin SE; Wu HP; Jeng WC; Hsu CC; Tiu CM; Chang T 《Radiology》1994,193(2):539
47.
48.
We report a case of a small, isolated paraspinal arteriovenous fistula (AVF) that arose in an adult without obvious trauma. The fistula, despite its extraspinal location and small size, caused hypertension of the intrathecal venous system and produced symptoms that were similar to those of spinal dural AVF. Detecting such a small lesion is difficult, but contrast-enhanced MR imaging can prove helpful in this regard. 相似文献
49.
Richard W. Bowtell Andrew Peters Jonathan C. Sharp Peter Mansfield Edward W. Hsu Nanci Aiken Anthony Horsman Stephen J. Blackband 《Magnetic resonance in medicine》1995,33(6):790-794
NMR microimages of single neural cells were acquired at 500 MHz using a conventional spin echo pulse sequence and a line-narrowing sequence that eliminates susceptibility effects. The data show that any contribution to the measured T2 relaxation rate arising from diffusion in local field inhomogeneities using spin echo sequences at high fields and high spatial resolution is relatively small. We conclude that the measured T2 difference between the nucleus and cytoplasm in these cells represents primarily a true T2 relaxation effect arising from the interactions of water with macromolecules in the two compartments and does not result from microsusceptibility differences. These observations have implications regarding water compartmentation in single cells and the interpretation of the MR characteristics of tissues in vivo. 相似文献
50.
Metabolic clearance rate (MCR) and production rate (PR) of calcitriol is decreased in experimental renal failure. In this experiment, we studied uremia and secondary hyperparathyroidism as possible causes of the abnormal calcitriol metabolism. Normal rats were made uremic by infusing phosphorus-free urine for 24 hours. Both the MCR (0.22 +/- 0.01 ml/min/kg, N = 6 P less than 0.001) and the PR (16.6 +/- 1.97 ng/kg/day, P less than 0.01) of calcitriol were significantly suppressed in normal rats following urine infusion when compared to saline infused rats (MCR, 0.30 +/- 0.01; PR, 32.9 +/- 4.1, N = 6). Different levels of protein intake by rats with renal failure produced by subtotal nephrectomy also alter the PR but not the MCR of calcitriol. Thus, the synthesis of calcitriol was significantly lower in rats with renal failure fed a high protein (50% protein) diet (17.6 +/- 0.7 ng/kg/day, N = 8, P less than 0.001) than in rats with renal failure fed a normal protein (20% protein) diet (22.2 +/- 1.4, N = 7). Thyroparathyroidectomy (TPTX) did not alter the MCR of calcitriol in renal failure, even though parathyroid hormone, which may suppress the degradation enzyme, could be elevated in this model of renal failure. The MCR of TPTXed rats with renal failure (0.15 +/- 0.01 ml/min/kg, N = 7) remained lower than that of the TPTXed control rats (0.19 +/- 0.01, N = 7, P less than 0.001), and chronic infusion of PTH to TPTXed rats with renal failure did not change the MCR of calcitriol (0.15 +/- 0.01, vs. control, 0.24 +/- 0.01).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献