全文获取类型
收费全文 | 514960篇 |
免费 | 34045篇 |
国内免费 | 622篇 |
专业分类
耳鼻咽喉 | 6919篇 |
儿科学 | 16927篇 |
妇产科学 | 13569篇 |
基础医学 | 85130篇 |
口腔科学 | 14521篇 |
临床医学 | 44499篇 |
内科学 | 94068篇 |
皮肤病学 | 12175篇 |
神经病学 | 36249篇 |
特种医学 | 18538篇 |
外国民族医学 | 63篇 |
外科学 | 77415篇 |
综合类 | 8494篇 |
一般理论 | 120篇 |
预防医学 | 39005篇 |
眼科学 | 12204篇 |
药学 | 40576篇 |
中国医学 | 1008篇 |
肿瘤学 | 28147篇 |
出版年
2018年 | 4977篇 |
2015年 | 4580篇 |
2014年 | 6128篇 |
2013年 | 9628篇 |
2012年 | 13029篇 |
2011年 | 14399篇 |
2010年 | 8369篇 |
2009年 | 7841篇 |
2008年 | 13812篇 |
2007年 | 14824篇 |
2006年 | 15045篇 |
2005年 | 14469篇 |
2004年 | 14137篇 |
2003年 | 13457篇 |
2002年 | 13313篇 |
2001年 | 24090篇 |
2000年 | 25088篇 |
1999年 | 20563篇 |
1998年 | 5433篇 |
1997年 | 4707篇 |
1996年 | 5042篇 |
1995年 | 4625篇 |
1994年 | 4321篇 |
1993年 | 4138篇 |
1992年 | 15726篇 |
1991年 | 16311篇 |
1990年 | 16423篇 |
1989年 | 15796篇 |
1988年 | 14577篇 |
1987年 | 14419篇 |
1986年 | 13598篇 |
1985年 | 12976篇 |
1984年 | 9628篇 |
1983年 | 8247篇 |
1982年 | 4560篇 |
1981年 | 4229篇 |
1979年 | 9418篇 |
1978年 | 6855篇 |
1977年 | 5772篇 |
1976年 | 5604篇 |
1975年 | 6397篇 |
1974年 | 7634篇 |
1973年 | 7132篇 |
1972年 | 6960篇 |
1971年 | 6686篇 |
1970年 | 6173篇 |
1969年 | 5889篇 |
1968年 | 5559篇 |
1967年 | 5012篇 |
1966年 | 4450篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
921.
M J Hershman R I Swift D T Reilly W A Logan J M Sackier H Gompertz J Horner N W Baker C B Wood 《Journal of the Royal College of Surgeons of Edinburgh》1990,35(1):29-32
This study compared one dose of cefotetan with three doses of piperacillin as prophylaxis against wound infection in 153 patients undergoing elective colorectal surgery. The patients were randomized into two groups: the first received 2 g cefotetan intravenously with induction of anaesthesia (n = 75), and the second received three doses of 2 g piperacillin (n = 78). Wound infection was defined as the presence of an abscess or discharging pus from the wound. In the cefotetan group there were 14 (19%) wound infections and 13 (17%) in the piperacillin group. There were three septic deaths, one in the cefotetan group and two in the piperacillin group. Both groups were comparable with regard to age, sex, nature of pathology and pre- and perioperative risk factors. No significant haematological or biochemical abnormalities were detected. The only adverse reaction was one patient who had an allergic reaction (rash) to piperacillin. These data suggest that single-dose cefotetan is as effective as triple-dose piperacillin in prophylaxis against infection in elective colorectal surgery. 相似文献
922.
N I Lisiany? S A Romodanov V A Rudenko R M Trosh A A Radzievski? Iu D Sosnov 《Klinichna khirurhiia / Ministerstvo okhorony zdorov'ia Ukra?ny, Naukove tovarystvo khirurhiv Ukra?ny》1990,(12):4-6
In patients with benign and malignant brain tumors before the operation, the suppression of the immune system, in particular, proliferative response of lymphocytes to T- and B-mitogens was established. Preoperative preparation of the patients aggravated this process. At day 8-10 after the operation, normalization of the main indices of immunity in patients with benign tumors was noted. In malignant tumors after the operation, the increase in the contents of T- and B-lymphocytes against the background of decrease in their proliferative activity was observed. 相似文献
923.
924.
Clinical evaluation of ceftibuten (CETB, 7432-S) was performed in 20 patients with acute bronchitis. They were consisted of 10 males and 10 females aged from 20 to 80 years old. CETB was given orally in daily dose of 300 mg (18 cases) or 600 mg (2 cases) in three divided portions. The duration of administration was 3 to 14 days. Especially they were given for 7 days in 16 cases. A total of 11 strains comprising 4 strains of Staphylococcus aureus, 2 strains of beta-Streptococcus and 1 strain each of Streptococcus pneumoniae, Branhamella catarrhalis, Klebsiella oxytoca, Serratia marcescens, Acinetobacter lwoffii were identified from sputa before administration. All of the above bacteria were eradicated but, in 1 case, a strain of Streptococcus pyogenes appeared after the treatment (eradication ratio = 100%). The clinical efficacy rate was 100%: Responses were excellent in 3 cases and good in 17 cases. There was no side effect and no abnormal changes in laboratory test results. From the avobe results, it is concluded that CETB is effective, safe and useful new oral cephem on acute bronchitis. 相似文献
925.
Immunomodulation of vascular endothelium. 1. Ultrastructural changes following ultraviolet B irradiation of peripheral veins 总被引:1,自引:0,他引:1
M L Marin R E Gordon M A Hardy K Reemtsma A I Benvenisty 《The Journal of surgical research》1990,48(2):134-143
Immunologic function of endothelial cells is especially important in consideration of vein allografting for arterial reconstruction and in organ allotransplantation. Ultraviolet B radiation (UVB) has previously been shown to modulate graft immunogenicity, and to alter cell surface receptor function. In this study, superficial epigastric veins were UVB irradiated with 10, 24, 40, 80, and 150 mJ/cm2 while control veins were not irradiated; all specimens were examined for endothelial ultrastructural changes. Veins were perfuse-fixed at 1, 3, 7, 14, and 28 days after irradiation, and were evaluated by transmission electron microscopy and scanning electron microscopy. Control veins had a normal appearing endothelial lining, composed of elongated, attenuated endothelial cells. Veins irradiated with more than 24 mJ/cm2 displayed injured endothelial cells characterized by altered microvilli, defects in the cell surface, and a change in cell shape. The degree of cell damage correlated closely with increasing UVB dose. At doses of 80 mJ/cm2 or greater there was moderate to severe endothelial cell separation from the underlying basement membrane and an increase in cellular lysosomes. The effects of UVB were maximal at 3 days with virtual recovery in resurfacing of all specimens with endothelium 28 days after irradiation. These data suggest that UVB has a dose-dependent effect on venous endothelium that is morphologically reversible with time. Cell membrane changes seen following exposure to UVB may contribute to altered cell surface receptor function. 相似文献
926.
Camphor and m-cresol mixtures are used in antiseptic and anti-itching creams. No compendial method exists for these preparations. This paper reports a capillary gas chromatographic method using FID detection with 2,6-di-tert-butyl-4-methylphenol as internal standard on a 30 m×0.32 mm Supelcowax®-10 column (0.25 μm film) with helium as carrier gas. Ramped temperature programming was applied. The method allows simultaneous quantitation of camphor and m-cresol in the presence of o- and p-cresols, calamine and zinc oxide. Overall percent recoveries (±SD, n=9) of camphor, o-, p- and m-cresol from spiked placebo creams, at a labeled amount of 10 (w/w)% were 96.9±0.6, 98.2±0.6, 99.2±0.5 and 101.0±0.9%, respectively, and at a labeled amount of 1% were 96.7±0.6, 97.8±0.9, 97.8±0.6, and 100.3±1.0%, respectively. The recovery studies were carried out at ±30% of the labeled amounts. Linear peak area or height ratios were obtained (r>0.999) for camphor, o-, p- and m-cresol covering a concentration range of 10–200% of the labeled amount. Linearity (r>0.999) was also obtained for m-cresol when the relative concentration of o- and p-cresol was varied from 5 to 100% of the m-cresol concentration. The resolution between the ‘critical pair’ of p- and m-cresol was ≥1.1. The limit of quantitation was 23 pg for m-cresol and 9.3 pg for camphor using an injection split of 1:50. The repeatability (%RSD) for all compounds were <2% for peak area and <1.4% for peak height ratios. System suitability and robustness of the method were established. The method was successively applied to the assay of available commercial products and allows assay of camphor and the three cresol isomers. 相似文献
927.
J F Hiehle Jr R I Grossman K N Ramer F Gonzalez-Scarano J A Cohen 《AJNR. American journal of neuroradiology》1995,16(1):69
PURPOSETo define the relationship between magnetization transfer and blood-brain-barrier breakdown in multiple sclerosis lesions using gadolinium enhancement as an index of the latter.METHODSTwo hundred twenty lesions (high-signal abnormalities on T2-weighted images) in 35 multiple sclerosis patients were studied with gadolinium-enhanced spin-echo imaging and magnetization transfer. Lesions were divided into groups having nodular or uniform enhancement, ring enhancement, or no enhancement after gadolinium administration. For 133 lesions, T1-weighted images without contrast enhancement were also analyzed. These lesions were categorized as isointense or hypointense based on their appearance on the unenhanced T1-weighted images.RESULTSThere was no difference between the magnetization transfer ratio (MTR) of lesions as a function of enhancement. MTR of hypointense lesions on unenhanced T1-weighted images was, however, lower than the MTR of isointense lesions.CONCLUSIONWe speculate that diminished MTR may reflect diminished myelin content and that hypointensity on T1-weighted images corresponds to demyelination. Central regions of ring-enhancing lesions had a lower MTR than the periphery, suggesting that demyelination in multiple sclerosis lesions occurs centrifugally. In addition, the short-repetition-time pulse sequence seems useful in the evaluation of myelin loss in patients with multiple sclerosis. 相似文献
928.
929.
Contradictory results have been reported about the inhibitory input to the medial rectus subdivision of the oculomotor nucleus of the cat. In the present ultrastructural study, we quantified the GABAergic and glycinergic terminals in the various subdivisions of the rabbit oculomotor nucleus with the use of post-embedding immunocytochemistry combined with retrograde tracing of horseradish peroxidase. The density of the GABAergic input to the medial rectus subdivision was as substantial as that to the other subdivisions and the postsynaptic distribution of the GABAergic and glycinergic innervation did not differ among the different oculomotor subdivisions. 相似文献
930.
Five cases are reported of spontaneous remission of chronic childhood thrombocytopenia four or more years after diagnosis. Other than typical features of chronic idiopathic thrombocytopenic purpura there were no obvious markers predictive of late remission, although a slow progressive recovery was common to four of the patients. In light of this experience splenectomy is not recommended in clinically mild thrombocytopenia. 相似文献