全文获取类型
收费全文 | 514651篇 |
免费 | 33428篇 |
国内免费 | 614篇 |
专业分类
耳鼻咽喉 | 6914篇 |
儿科学 | 16849篇 |
妇产科学 | 13540篇 |
基础医学 | 85139篇 |
口腔科学 | 14488篇 |
临床医学 | 44374篇 |
内科学 | 93770篇 |
皮肤病学 | 12160篇 |
神经病学 | 36290篇 |
特种医学 | 18459篇 |
外国民族医学 | 63篇 |
外科学 | 77145篇 |
综合类 | 8476篇 |
一般理论 | 118篇 |
预防医学 | 39006篇 |
眼科学 | 12155篇 |
药学 | 40589篇 |
中国医学 | 1006篇 |
肿瘤学 | 28152篇 |
出版年
2018年 | 4944篇 |
2015年 | 4528篇 |
2014年 | 6074篇 |
2013年 | 9569篇 |
2012年 | 12902篇 |
2011年 | 14316篇 |
2010年 | 8320篇 |
2009年 | 7785篇 |
2008年 | 13724篇 |
2007年 | 14738篇 |
2006年 | 14977篇 |
2005年 | 14393篇 |
2004年 | 14081篇 |
2003年 | 13412篇 |
2002年 | 13293篇 |
2001年 | 24080篇 |
2000年 | 25103篇 |
1999年 | 20574篇 |
1998年 | 5433篇 |
1997年 | 4714篇 |
1996年 | 5044篇 |
1995年 | 4630篇 |
1994年 | 4322篇 |
1993年 | 4139篇 |
1992年 | 15742篇 |
1991年 | 16323篇 |
1990年 | 16439篇 |
1989年 | 15805篇 |
1988年 | 14587篇 |
1987年 | 14430篇 |
1986年 | 13610篇 |
1985年 | 12982篇 |
1984年 | 9630篇 |
1983年 | 8252篇 |
1982年 | 4562篇 |
1981年 | 4230篇 |
1979年 | 9423篇 |
1978年 | 6859篇 |
1977年 | 5774篇 |
1976年 | 5603篇 |
1975年 | 6403篇 |
1974年 | 7635篇 |
1973年 | 7132篇 |
1972年 | 6961篇 |
1971年 | 6688篇 |
1970年 | 6175篇 |
1969年 | 5888篇 |
1968年 | 5559篇 |
1967年 | 5012篇 |
1966年 | 4453篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Perceptual asymmetry on a series of four specially constructed dichotic word tests was found to change as a function of the emotional quality of the words in the tests (P = 0.05). This was most pronounced in the case of positively valued words which produced an increase in asymmetry consistent with facilitated left-hemisphere function (P less than 0.004). Changes in asymmetry with emotion differed as a function of personality characteristics of the subjects, with repressors and high anxious subjects showing an increase with emotion while true low anxious subjects showed a decrease (P less than 0.02). Personality groups also differed in asymmetry on an emotionally neutral test (P less than 0.04) and in changes in asymmetry over time independent of emotion (P less than 0.001). These data suggest that emotion mediated activation of the left hemisphere may facilitate information processing within that hemisphere. Moreover, they indicate that dichotic listening tests may provide a non-invasive and inexpensive method for assessing emotion mediated changes in brain state that are clinically relevant. 相似文献
62.
63.
S B Wieslander B T Mortensen L Binderup N I Nissen 《European journal of haematology》1987,39(1):35-38
10 patients with CLL and 2 with CML were treated with gradually increasing doses of 1 alpha(OH)D3, up to 4 micrograms daily during 6 wk. 3 patients with preleukemia and 1 with myelofibrosis were treated with 2 micrograms daily of 1 alpha(OH)D3 for a prolonged period up to 17 wk. The treatment with 1 alpha (OH)D3 did not result in changes of disease parameters in any of the patients under study. Receptor studies for 1,25(OH)2D3 were performed in 8 CLL patients and revealed only 1 patient with increased specific receptor binding capacity. The maximum tolerable dose of 1 alpha(OH)D3 varied individually, but was in the range of 2-4 micrograms daily. 相似文献
64.
65.
66.
Carnitine status in Reye and Reye-like syndromes 总被引:4,自引:0,他引:4
Fourteen children with the following Reye and Reye-like syndromes were studied to determine each patient's carnitine status: valproate-induced Reye-like attack, ornithine transcarbamylase deficiency, systemic carnitine deficiency, methylmalonic acidemia, and propionic acidemia. Reduced free carnitine and increased serum and urine acylcarnitine levels were found in all patients except for 2 with Reye syndrome, in whom serum creatinine levels were mildly elevated and serum free carnitine levels were not reduced. The renal free carnitine reabsorption rate was reduced in all cases. The free carnitine content of autopsied liver samples were reduced in 2 Reye syndrome patients, 2 OTC deficiency patients, and in a single systemic carnitine deficiency patient. The observed secondary free carnitine deficiency may be a factor in the pathogenesis of Reye and Reye-like syndromes. 相似文献
67.
68.
The purpose of this study was to evaluate a new fluorescence polarization immunoassay, TDx, for digitoxin by comparing the results of this assay with those of a radioimmunoassay (RIA). Thirty-three serum samples were obtained from 15 patients during, and for 4 weeks after, a 4-week course of digitoxin therapy. Each sample was separated by centrifugation, coded, and frozen until analysis. At the time of analysis, each sample was divided and analyzed simultaneously by TDx and RIA. Nine samples yielded results less than 2 ng/ml (limit of assay sensitivity) by one or both methods and were excluded from further data analysis. Linear regression analysis of the results of the remaining 24 paired samples (x = TDx, y = RIA) revealed a strong correlation coefficient of r2 = 0.95, slope = 0.95, and a y intercept of -0.99 (y = -0.99 + 0.95x). Additionally, the TDx results were lower than the RIA values in only five of 33 paired samples; and these occurred in four patients who had a significantly lower mean estimated creatinine clearance than that of the other 11 patients (39.0 +/- 9.1 ml/min/1.73 m2 vs. 63.3 +/- 11.8 ml/min/1.73 m2, p less than 0.01). The TDx system is a comparable alternative to the RIA method, but differences in specificity and sensitivity may exist and should be evaluated more thoroughly. 相似文献
69.
Summary The left recurrent laryngeal nerves from five horses with sub-clinical neuropathy were examined by light and electron microscopy in a study designed to examine accumulation of axonal organelles at paranodal and internodal locations. Transverse sections of the nerve showed scattered fibres with split myelin sheaths and axonal accumulation of organelles. On longitudinal sections these collections were seen to result from an axonal outpouching in which dense lamellar bodies and mitochondria had accumulated. These paranodal collections, which could be found on both sides of the node, were often associated with infoldings of the terminal loops of myelin and with occasional paranodal demyelination. The fact that many of the organelles in the outpouches were lysosomal in nature was confirmed by their positive staining for cathepsin D activity. Longitudinal sections demonstrated a number of axons which were swollen over a long distance and which contained focal accumulations of similar organelles. In places, however, there was a clear separation between these organelles and the cytoskeletal proteins. In each case these swollen axons were surrounded by Schwann cell nuclei and their processes, forming well-ordered onion bulbs. The possibility that these two types of changes, i.e. the paranodal accumulations and the axonal swellings could result from a disturbance in axonal transport in this distal axonopathy is discussed. 相似文献
70.
Laser-light scattering was used to observe and quantify the dynamics of human blood platelet aggregation in platelet-rich plasma (PRP). Aggregation was performed in a controlled shear environment by placing the PRP in the annular space between a rotating cylindrical rod and a stationary cylindrical tube. The instrument was capable of very sensitive continuous semi-quantitative measurements of chemically-induced microaggregation. As a demonstration of the technique, results are presented for ADP-induced aggregation at doses of 10, 1, and 0.1 microM and collagen-induced aggregation at a dose of 5 micrograms/ml, each at shear rates of 1,000 s-1 and 500 s-1. Extensive aggregation was observed in response to ADP at even the low dose of 0.1 microM, indicating a high sensitivity to microaggregates. The sensitivity of the ultimate size of the ADP-induced aggregates to ADP concentration was shear dependent. The formation of microaggregates by collagen stimulation was shown to be almost immediate, as contrasted with a 10-20 s typical lag when observed turbidometrically. Disaggregation was observed with 1 microM ADP, but this was only partial, as contrasted with the complete recovery of transmittance observed in the turbidometric technique. Electronic particle sizing and counting was employed to semiquantitatively verify the aggregate size distributions found from mathematical conversion of the laser-light scattering data. 相似文献