全文获取类型
收费全文 | 7583篇 |
免费 | 397篇 |
国内免费 | 221篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 297篇 |
妇产科学 | 100篇 |
基础医学 | 1231篇 |
口腔科学 | 95篇 |
临床医学 | 660篇 |
内科学 | 1202篇 |
皮肤病学 | 64篇 |
神经病学 | 558篇 |
特种医学 | 124篇 |
外国民族医学 | 2篇 |
外科学 | 375篇 |
综合类 | 921篇 |
现状与发展 | 1篇 |
预防医学 | 371篇 |
眼科学 | 60篇 |
药学 | 1409篇 |
1篇 | |
中国医学 | 213篇 |
肿瘤学 | 490篇 |
出版年
2023年 | 81篇 |
2022年 | 174篇 |
2021年 | 235篇 |
2020年 | 191篇 |
2019年 | 184篇 |
2018年 | 197篇 |
2017年 | 178篇 |
2016年 | 206篇 |
2015年 | 182篇 |
2014年 | 399篇 |
2013年 | 400篇 |
2012年 | 403篇 |
2011年 | 476篇 |
2010年 | 333篇 |
2009年 | 340篇 |
2008年 | 342篇 |
2007年 | 315篇 |
2006年 | 316篇 |
2005年 | 296篇 |
2004年 | 245篇 |
2003年 | 228篇 |
2002年 | 202篇 |
2001年 | 171篇 |
2000年 | 123篇 |
1999年 | 141篇 |
1998年 | 113篇 |
1997年 | 117篇 |
1996年 | 106篇 |
1995年 | 109篇 |
1994年 | 116篇 |
1993年 | 80篇 |
1992年 | 87篇 |
1991年 | 79篇 |
1990年 | 80篇 |
1989年 | 73篇 |
1988年 | 82篇 |
1987年 | 56篇 |
1986年 | 56篇 |
1985年 | 111篇 |
1984年 | 96篇 |
1983年 | 51篇 |
1982年 | 53篇 |
1981年 | 65篇 |
1980年 | 63篇 |
1979年 | 49篇 |
1978年 | 51篇 |
1977年 | 35篇 |
1976年 | 36篇 |
1974年 | 17篇 |
1973年 | 19篇 |
排序方式: 共有8201条查询结果,搜索用时 15 毫秒
31.
Morphologic evaluation of the liver in hereditary angioedema patients on long-term treatment with androgen derivatives 总被引:1,自引:0,他引:1
M Cicardi L Bergamaschini A Tucci A Agostoni G Tornaghi G Coggi R Colombi G Viale 《The Journal of allergy and clinical immunology》1983,72(3):294-298
17 alpha-Alkylated androgens are highly effective in preventing attacks in HAE patients. These drugs, however, seem to be implicated in the development of cholestatic jaundice, peliosis hepatis, and liver tumors. In order to assess the risk-benefit balance of the long-term therapy with androgen derivatives, a follow-up investigation was performed in 13 HAE patients. The results of this study indicate that long-term treatment (15 to 47 mo) with low doses of danazol or stanozolol does not induce significant hepatic damage detectable by laboratory tests or liver biopsy. However, the limited number of patients, although in a rather long period of observation, still suggests a careful control and the use of minimal effective doses. 相似文献
32.
M. Ikeda M. Matsusaki A. Kinoshita M. Koga M. Ideishi M. Sasaguri H. Tanaka M. Shindo K. Arakawa 《European journal of applied physiology》1992,65(4):331-334
Summary The effects of graded exercise on plasma concentrations of active and inactive renin were studied in seven healthy men. Exercise was performed on a cycle ergometer at four different exercise intensities (corresponding to 30%, 50%, 80% and 87% of
) for 10 min each. Concentrations of active renin and total renin after activation by trypsin were measured by direct immunoradiometric assay. Non-trypsin-activated renin concentration (inactive) was obtained by subtraction. Active renin concentrations at 30%, 50%, 80% and 87% of
were 1.2, 1.9, 3.1 and 4.6 times higher than the control concentration, respectively. Similar increases in plasma renin concentration, determined by conventional enzymatic assay, were observed at every stage. In contrast, changes in inactive renin concentration were not significant at any stage. Significant increases in noradrenaline concentration were found at every exercise stage, but adrenaline, aldosterone and lactate concentrations were significantly elevated only after exercise at 50%, 80% and 87% of
. The similarity between the changes in concentration of active renin and noradrenaline would suggest that sympathetic nerve activity may have been responsible either for the release of active renin or for the conversion of inactive renin to its active form in the kidney. 相似文献
33.
Effects of endurance training on myosin heavy-chain isoforms and enzyme activity in the rat diaphragm 总被引:2,自引:0,他引:2
Takao Sugiura Akio Morimoto Naotoshi Murakami 《Pflügers Archiv : European journal of physiology》1992,421(1):77-81
We investigated the effects of endurance training (20 m/min, 60 min/day, 5 days/week) on myosin heavy-chain (MHC) isoforms and succinic dehydrogenase (SDH) activity in rat crural and costal diaphragms, and plantaris muscles. Although the 4-week endurance training produced significant (P<0.05) increases, both in SDH activity and the percentage of isoform HCIIa in the plantaris of the trained rat compared with the sedentary control rat, these alterations did not occur in either the crural or costal diaphragms. After 10 weeks of endurance training, trained animals had significantly (P<0.05) higher SDH activity in the costal diaphragm and the plantaris. Moreover, a significant (P<0.05) decrease occurred in the percentage of HCIIb in the costal diaphragm, and a significant (P<0.01) decrease in the percentage of HCIIb concomitant with a significant (P<0.05) increase of HCIIa resulted in the plantaris. However, the crural diaphragm did not show any significant changes after 10 weeks of endurance training. These results indicate that endurance training induces an alteration in the expression of an MHC phenotype, in addition to causing an increase in oxidative enzyme activity. However, the alterations in response to endurance training are apparently not uniform, varying between regions and/or kinds of muscles. 相似文献
34.
35.
Dr. M. Kallerhoff M. Blech G. Kehrer H. Kleinert M. Langheinrich W. Siekmann U. Helmchen H. J. Bretschneider 《Urological research》1987,15(4):215-222
Summary Energy reserves (TAN) and anaerobic substrates (glucose, glycogen) are lower in renal than in myocardial tissue. Euro-Collins-solution contains nearly 200 mmol/l glucose, while the HTK-solution of Bretschneider contains none. Therefore the influence of glucose on kidney lactate production, on energy reserves (TAN), intrarenal pH and on morphology during the protection of ischemic kidneys was analysed using either Euro-Collins-solution, or modified Euro-Collins-solution, containing mannitol instead of glucose, or HTK-solution with and without the addition of 5, 10 and 20 mmol/l glucose. Glucose content changed during kidney perfusion with Euro-Collins-solution from about 60 to 800 mol/gdw. While intrarenal pH decreased from 7.1 to 5.1 in Euro-Collins-kidneys during 420 min of ischemia at 25°C, pH decreased to 6.7 with the modified, mannitol containing Euro-Collins-solution. In HTK-protected kidneys intrarenal pH decreased with increasing glucose addition to the solution. Although Total Adenine Nucleotides are highest at the end of ischemia with Euro-Collins-solution, structural protection after the same ischemic stress was best in HTK-protected kidneys without glucose addition. We conclude that glucose stimulated lactate production, reduced interstitial pH in the kidney even in combination with a highly buffered solution and that it might cause greater membrane permeability leading to a structural detoriation. Mannitol seemed more appropriate than glucose in this respect, although other substances, which provide energy substrate and prevent structural damage, may exist.Supported by the Deutsche Forschungsgemeinschaft, SFB 89 —Kardiologie Göttingen 相似文献
36.
R. Andrzejak R. Smolik 《International archives of occupational and environmental health》1984,54(4):303-308
Summary In investigating the influence of vibrational energy on the metabolism of the erythrocyte, it was hypothesized that under conditions of normal PaO2 and SaO2 in arterial blood, vibration induced vasoconstriction would decrease local blood flow and induce hypokinetic hypoxia. This decreased blood flow and therefore decreased delivery of oxygen to the tissue would markedly lower tissue PO2 (hypokinetic hypoxia), which would influence the energetics and metabolism of the erythrocyte. The metabolism of the red blood cell (RBC) was evaluated by measuring the enzymatic activities of PFK (2.7.1.11), PGI (5.3.1.9), PK (2.7.1.40), and aldolase (4.1.3.13) from the anaerobic glycolytic cycle and D-G-6-P (1.1.1.49) from the pentose cycle. Also measured were the levels of ATP and 2,3 DPG and the in-vitro production of lactic acid. In the group of workers showing early changes (vibration angioneurosis) associated with the vibration syndrome, changes in RBC metabolism were demonstrated. Statistically significant were increases of PFK, PK and the production of lactic acid, indicating the activation of anaerobic glycolysis. Furthermore statistically significant were the increased 2,3 DPG and decreased ATP levels. 相似文献
37.
Jean L. Grem Larry Rubinstein Susan A. King Bruce D. Cheson Michael J. Hawkins Dale D. Shoemaker 《Investigational new drugs》1990,8(2):227-238
Summary Tiazofurin, an investigational antimetabolite, is undergoing clinical evaluation in leukemia. We analyzed the data base of 198 patients entered in Phase I trials to characterize the incidence and severity of toxicities associated with tiazofurin according to dose and schedule. Severe myelosuppression occurred infrequently, and was not dose-dependent. A five day bolus schedule had a higher incidence of severe or life-threatening neutropenia than other schedules. Tiazofurin produced lymphopenia which was not dose-dependent in the range of 23–36% decrease from baseline, and the effect on lymphocyte count was generally greater than the decline in neutrophil count. Non-hematologic toxicity of a moderate or worse severity ( grade 2) included nausea and vomiting (18% of all courses), serum transaminase elevations (SGOT, 16%; SGPT, 9%), rash (9%), stomatitis (3%), conjunctivitis (3%), headache (10%), other signs of central nervous system toxicity (8%), and cardiac toxicity, primarily pleuropericarditis (4%). Dose-related cutaneous toxicity, headache, and nausea and vomiting were evident in the five day bolus schedule, and myalgia was more frequently reported at higher doses on the single dose schedule. The five day continuous infusion (CI) schedule had a higher incidence of neurotoxicity, cardiac toxicity, SGPT elevations and ocular toxicity than the daily for five days bolus schedule, but none of these differences attained statistical significance. Although the peak plasma concentrations of tiazofurin achieved with the five day bolus schedule were 3-fold higher than the steady-state plasma levels seen with an equal dose given by CI, the area under the concentration-time curve (AUC) was approximately 1.6-fold higher with CI. These observations suggest that both high peak plasma concentrations (above 400 uM) and prolonged exposure to plasma levels exceeding 50 uM may result in a higher incidence of serious non-hematologic toxicity. 相似文献
38.
We have obtained a clone of the Pichia pastoris HIS4 gene and have determined its nucleotide sequence. Based upon its deduced amino-acid sequence, the product of the P. pastoris HIS4 gene has the same structural organization as the Saccharomyces cerevisiae His4 protein and appears to encode a trifunctional enzyme catalyzing the second (phosphoribosyl-ATP pyrophosphohydrolase), third (phosphoribosyl-AMP cyclohydrolase), and tenth (histidinol dehydrogenase) steps in histidine biosynthesis. The chromosomal copy of the HIS4 gene was disrupted by homologous recombination, creating the strain SGY58. The his4 deletion mutation in this strain lacks the entire coding region of this gene and has a reversion rate that is undetectable. A set of complementary plasmids that carry the HIS4 gene was also developed. Among these are nine E. coli-P. pastoris shuttle vectors that transform the His4 deletion mutant at high efficiency and an integration vector for creating site-specific alterations of the P. pastoris genome. 相似文献
39.
Background: this study was designed to characterize some of the biochemical and molecular genetic changes during reversion
of human fat cells. Methods: mature adipocytes were isolated from greater omental fat tissue of eight lean and 14 massively
obese persons by established methodology. Results: at day 7 of adherence to Leighton tubes, there was appreciable depletion
of triacylglycerol, as well as assumption of an elongated contour. Relatedly, there was an increase in the expression of β-actin
mRNA and a significant decrease in the specific activity of cytosolic glycerophosphate dehydrogenase. The decrement in the
specific activity of glycerophosphate dehydrogenase, after 7 days in culture, was significant at p < 0.001. Basic fibroblast growth factor at 10 ngml-1 accelerated significantly (p < 0.03) the decrease in the specific activity of glycerophosphate dehydrogenase in adipose cells from lean subjects. In contrast,
basic fibroblast growth factor had no significant influence on cells from massively obese persons. Conclusion: such resistance
may contribute to the intractability of massive obesity. 相似文献
40.
R. Moore J. F. T. Glasgow M. A. Bingham J. A. Dodge R. J. Pollitt S. E. Olpin B. Middleton K. Carpenter 《European journal of pediatrics》1993,152(5):433-436
Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD), the third enzyme of the mitochondrial -oxidation pathway, carries out the dehydrogenation of 3-hydroxyacyl-CoA compounds of 12–18 carbon length. To date only nine cases of LCHAD deficiency have been documented. We report a further patient who as a neonate developed non-specific gastro-intestinal symptoms and at 5 months of age cardiomyopathy, recurrent hypoketotic hypoglycaemia and gross alterations of plasma carnitine fractions. Dietary management with medium chain triglycerides led rapidly to clinical improvement. There was a close correlation between the clinical condition, plasma carnitine fractions and cardiac function. At 2 years of age she is developing normally. 相似文献