全文获取类型
收费全文 | 1073580篇 |
免费 | 73154篇 |
国内免费 | 1363篇 |
专业分类
耳鼻咽喉 | 15015篇 |
儿科学 | 34608篇 |
妇产科学 | 28624篇 |
基础医学 | 153421篇 |
口腔科学 | 29553篇 |
临床医学 | 94934篇 |
内科学 | 203643篇 |
皮肤病学 | 24392篇 |
神经病学 | 81439篇 |
特种医学 | 42967篇 |
外国民族医学 | 201篇 |
外科学 | 163131篇 |
综合类 | 21702篇 |
现状与发展 | 1篇 |
一般理论 | 263篇 |
预防医学 | 74600篇 |
眼科学 | 24535篇 |
药学 | 86183篇 |
7篇 | |
中国医学 | 2805篇 |
肿瘤学 | 66073篇 |
出版年
2019年 | 7756篇 |
2018年 | 11293篇 |
2017年 | 8906篇 |
2016年 | 10094篇 |
2015年 | 11260篇 |
2014年 | 15268篇 |
2013年 | 22198篇 |
2012年 | 30548篇 |
2011年 | 32294篇 |
2010年 | 18958篇 |
2009年 | 17821篇 |
2008年 | 29955篇 |
2007年 | 32075篇 |
2006年 | 32714篇 |
2005年 | 31049篇 |
2004年 | 29750篇 |
2003年 | 28565篇 |
2002年 | 27546篇 |
2001年 | 60032篇 |
2000年 | 61483篇 |
1999年 | 50935篇 |
1998年 | 12444篇 |
1997年 | 11004篇 |
1996年 | 11018篇 |
1995年 | 10321篇 |
1994年 | 9342篇 |
1993年 | 8857篇 |
1992年 | 37795篇 |
1991年 | 36277篇 |
1990年 | 35751篇 |
1989年 | 34292篇 |
1988年 | 30867篇 |
1987年 | 29986篇 |
1986年 | 28216篇 |
1985年 | 26451篇 |
1984年 | 19185篇 |
1983年 | 16117篇 |
1982年 | 8824篇 |
1979年 | 17029篇 |
1978年 | 11404篇 |
1977年 | 10229篇 |
1976年 | 8837篇 |
1975年 | 10069篇 |
1974年 | 11652篇 |
1973年 | 11273篇 |
1972年 | 10754篇 |
1971年 | 10094篇 |
1970年 | 9252篇 |
1969年 | 8938篇 |
1968年 | 7918篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Relatedness of structures of a major immunogen in Trichomonas vaginalis isolates. 总被引:7,自引:3,他引:4 下载免费PDF全文
Solubilization of live Trichomonas vaginalis organisms with detergent caused the release of cysteine proteinases in the detergent extract which were inhibitable with N-alpha-p-tosyl-L-lysine chloromethyl ketone. The detergent extracts of all isolates tested possessed similar cysteine proteinase activities. These parasite proteinases rapidly degraded a prominent immunogen whose surface disposition undergoes phenotypic variation in some isolates. The relatedness of the forms of this immunogen among all isolates tested was confirmed by identical immunoblot patterns of autolysed immunogen, and data suggest the presence of repeating units or at least equidistant sites for proteinase cleavage within the immunogen molecule. 相似文献
992.
Atrial natriuretic peptide (ANP) is a hormone release into the circulation by atrial cardiocytes (Gutkowska et al. 1984). Extracellular fluid volume expansion acts as a powerful stimulus for ANP secretion and results in the augmentation of its plasma concentration (Lang et al. 1985). Patients with active acromegaly demonstrate the increased extracellular fluid volume (Falkheden et al. 1964), while a successful treatment of the disease results in the disappearance of hypervolemia (Strauch et al. 1977). We have recently demonstrated that in patients with active acromegaly the increased total body plasma volumes are accompanied by the elevated plasma ANP concentrations, whereas, in the successfully treated patients, both: total plasma volumes and plasma ANP levels do not differ significantly from these in healthy subjects (Czekalski et al. 1988b). 相似文献
993.
K Andersson 《Acta physiologica Scandinavica》1989,135(4):449-457
The effects of SCH 23390 (D1 dopamine receptor antagonist), SK&F 38393 (D1 dopamine receptor agonist), raclopride and remoxipride (D2 dopamine receptor antagonists) and ketanserin (5-hydroxytryptamine 2 receptor antagonist) on TSH serum levels (radioimmunoassay) and on brain catecholamine levels (Falck-Hillarp methodology in combination with quantitative histofluorimetry) were studied. SCH 23390 produced a dose-dependent increase in serum TSH levels in the lower dose range (0.01-0.03 mg kg-1, i.p.) administered 30 min before decapitation and in the higher dose range (1.0-3.0 mg kg-1) when given 2 h before decapitation. Following 30 min of treatment with the high doses of SCH 23390, reductions in serum TSH levels were found. The changes observed following SCH 23390 treatment occurred without affecting catecholamine levels in the median eminence and the peri- and paraventricular hypothalamic regions. Raclopride (0.1-10 mg kg-1, i.p.), remoxipride (1.0 mg kg-1, i.p.) or ketanserin (0.3 mg kg-1, i.p.) changed neither serum TSH levels nor brain catecholamine levels, SK&F 38393 (1.0-10 mg kg-1, i.p.) produced an increase in serum TSH levels. The results suggest the existence of inhibitory and facilitatory mechanisms regulating TSH secretion mediated via D1 dopamine receptors. 相似文献
994.
995.
Saponins from Thinouia coriacea] 总被引:2,自引:0,他引:2
The investigation of the stems of Thinouia coriacea Britton (Sapindaceae), an ichthyotoxic plant from South Brazil, afforded eight glycosides of oleanolic acid. Structures were assigned based on data from partial hydrolysis. 13C-NMR and mass spectral procedures as 3-O-alpha-L-arabinopyranoside (1), 3-O-alpha-L-rhamnopyranosyl-(1----2)-alpha-L-arabinopyranoside+ ++ (2), 3-O-beta-D-glucopyranosyl-(1----4)-alpha-L-arabinopyranoside (3), 3-O-beta-D-glucopyranosyl-(1----3)-alpha-L-rhamnopyranosyl-(1----2 )-alpha-L-arabinopyranoside (4), 3-O-alpha-L-rhamnopyranosyl-(1----2)[beta-D-glucopyranosyl-(1----4 )]-alpha-L-arabinopyranoside (5), 3-O-beta-D-xylopyranosyl-(1----3)-alpha-L-rhamnopyranosyl-(1----2) [beta-D-glucopyranosyl-(1----4)[alpha-L-arabinopyranoside (6), 3-O-beta-D-glucopyranosyl-(1----3)-alpha-L-rhamnopyranosyl-(1----2 )[beta-D-glucopyranosyl-(1----4)]-alpha-L-arabinopyranoside (8). Saponin 7 showed the same sugars as 8, but the attachment between the sugars could not be elucidated. The same saponins were present in the roots, but not in the leaves. 相似文献
996.
Total circulating platelet count and thrombocytogram were examined in 60 tobacco smokers and in 30 nonsmoking normal subjects aged 23-32. The smokers were divided into two subgroups, 30 subjects in each: Group 1 included those with a history of smoking under 5 years and Group 2 those smoking for 5 years and Group 2 those smoking for 6-10 years. The platelet count was found increased in Group 1 smokers at the expense of old, atypical, and involutional forms. In Group 2 smokers the total platelet count and the counts of their differentiation forms were reduced. This evidences the effect of tobacco smoking on circulating platelets, this effect depending on the length of tobacco smoke inhalation. 相似文献
997.
A lawsuit directed by parents at a day care program following an outbreak of infectious disease would most likely be based on the legal theory of negligence--the failure to exercise due care as required by circumstances. In the determination of liability for infectious diseases in child day care, the element of causation is most critical. Did the day care facility's actions or failure to act cause the harm? Another important question is whether an infectious disease can be occupational and under what circumstances. Although worker's compensation laws initially had no provisions for occupational disease, now all states recognize responsibility for them. Awareness of potential problems with legal liability and establishment of procedures to minimize risk are important for day care providers, public health officials, clinicians, and parents. 相似文献
998.
999.
Direct (intraarterial) and two indirect (using a mercury sphygmomanometer [MS] and an automatic [auscultatory] device) methods of blood pressure measurement were compared in intensive care patients (N = 32). One trained observer blind to both automatic and direct measurements obtained all indirect MS measurements. All direct and indirect measurements were made on the same arm. Direct measurements were obtained from 10-second strip chart recordings. In normotensive patients both indirect measurements of systolic blood pressure (SBP) underestimated the direct SBP; however, only the SBP value obtained with the automatic device (106 mm Hg) was significantly different, p less than .05, from the direct SBP value (120 mm Hg). No significant difference was noted between methods in measurement of normotensive diastolic blood pressure. In hypertensive patients direct SBP was significantly greater, p less than .05, from both values obtained by indirect measurement. In patients without hypotension the automatic device may be substituted for the MS and direct blood pressure methods. The automatic device may offer the advantage of decreasing observer bias and variability in blood pressure measurement. 相似文献