全文获取类型
收费全文 | 1924107篇 |
免费 | 136417篇 |
国内免费 | 4362篇 |
专业分类
耳鼻咽喉 | 25535篇 |
儿科学 | 63498篇 |
妇产科学 | 52313篇 |
基础医学 | 274193篇 |
口腔科学 | 55463篇 |
临床医学 | 168599篇 |
内科学 | 379741篇 |
皮肤病学 | 45615篇 |
神经病学 | 152050篇 |
特种医学 | 73540篇 |
外国民族医学 | 293篇 |
外科学 | 291429篇 |
综合类 | 40318篇 |
现状与发展 | 4篇 |
一般理论 | 585篇 |
预防医学 | 139267篇 |
眼科学 | 45571篇 |
药学 | 139783篇 |
7篇 | |
中国医学 | 5061篇 |
肿瘤学 | 112021篇 |
出版年
2021年 | 16246篇 |
2019年 | 16859篇 |
2018年 | 24776篇 |
2017年 | 18792篇 |
2016年 | 20987篇 |
2015年 | 23735篇 |
2014年 | 32073篇 |
2013年 | 46234篇 |
2012年 | 65179篇 |
2011年 | 67649篇 |
2010年 | 39900篇 |
2009年 | 36976篇 |
2008年 | 62767篇 |
2007年 | 66817篇 |
2006年 | 67282篇 |
2005年 | 64909篇 |
2004年 | 62303篇 |
2003年 | 59408篇 |
2002年 | 57387篇 |
2001年 | 98501篇 |
2000年 | 100507篇 |
1999年 | 83077篇 |
1998年 | 21809篇 |
1997年 | 18944篇 |
1996年 | 18715篇 |
1995年 | 17864篇 |
1994年 | 16299篇 |
1993年 | 14991篇 |
1992年 | 60317篇 |
1991年 | 58205篇 |
1990年 | 55770篇 |
1989年 | 53321篇 |
1988年 | 48462篇 |
1987年 | 47245篇 |
1986年 | 44401篇 |
1985年 | 42060篇 |
1984年 | 30964篇 |
1983年 | 26279篇 |
1982年 | 14812篇 |
1979年 | 27196篇 |
1978年 | 18774篇 |
1977年 | 15941篇 |
1976年 | 14776篇 |
1975年 | 15871篇 |
1974年 | 18998篇 |
1973年 | 18233篇 |
1972年 | 16906篇 |
1971年 | 15669篇 |
1970年 | 14529篇 |
1969年 | 13566篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
The effect of lysozyme-inactivation on L(+)-lactic acid (LA) production in dental plaque suspensions was evaluated. From 10 children 24-h plaque was collected and lysozyme activity inhibited by addition of goat antiserum to human lysozyme. Acid production was stimulated by addition of glucose. The results showed significantly increased LA levels (50-150%) in lysozyme-inactivated plaque suspensions from 8 of the subjects compared to untreated controls. The increase in acid production activity was not related to plaque lysozyme levels. The findings indicate that the presence of lysozyme may be limiting on acid production in the early dental plaque. 相似文献
982.
983.
Regulation of guinea pig ileal electrolyte transport by M3-muscarinic acetylcholine receptors in vitro 总被引:2,自引:0,他引:2
To determine the muscarinic receptor subtype mediating guinea pig ileal mucosal electrolyte secretion, we compared the potencies (Kb) of selective M1 (pirenzepine) (PZ), M2 (AF-DX 116, methoctramine), and M3 [4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP), hexahydrosiladifenidol (HHSiD)] antagonists as inhibitors of carbachol-induced reductions in guinea pig atrial heart rate and ileal longitudinal muscle contractions, responses mediated by M2 and M3 receptors, respectively. Pretreatment with all five muscarinic antagonists shifted the carbachol concentration-response curve to the right, in a manner suggesting competitive antagonism. The following affinity profiles (Kb, nM) were obtained for: 1) ileal mucosa: 4-DAMP (2.7) greater than HHSiD (23.0) greater than PZ (110) greater than or equal to methoctramine (395) greater than AF-DX 116 (784); 2) atrial heart rate: 4-DAMP (9.5) congruent to methoctramine (11) greater than AF-DX 116 (63) greater than HHSiD (222) greater than PZ (256); and 3) ileal longitudinal muscle: 4-DAMP (3.1) greater than HHSiD (21) greater than PZ (143) greater than methoctramine (388) greater than or equal to AF-DX 116 (482). The selectivity profiles of these antagonists suggest that muscarinic receptors in the ileal mucosa more closely resemble those in the ileal muscle (M3) than those in atrial muscle (M2). Moreover, M1-muscarinic receptors appear to be relatively unimportant in mediating the effects of carbachol on short circuit current (ISC). Carbachol-induced increases in ISC were also unaffected by pretreatment with 0.5 microM tetrodotoxin, suggesting that electrolyte transport in the guinea pig ileal mucosa may be mediated, in part, by postsynaptic M3-muscarinic receptors on the enterocytes. 相似文献
984.
H Murakami M Togawa S Takahashi N Kasahara J Yamamoto N Matsuura Y Koshiyama Y Ino M Oda 《Arzneimittel-Forschung》1990,40(12):1352-1358
The effects of FUT-187 (6-amidino-2-naphthyl 4-[(4,5-dihydro-1H-imidazol-2-yl)amino]benzoate dimethanesulfonate, CAS 103926-82-5), a novel synthetic protease inhibitor, were examined in experimental rat and canine models of pancreatitis. 1. FUT-187 significantly increased the survival of rats with trypsin- and phospholipase A2-induced pancreatitis in a dose-dependent manner (10-100 mg/kg, p.o.). 2. FUT-187 decreased plasma enzymatic activity reflecting the degree of pancreatitis in rats with ethionine-induced pancreatitis, and showed a tendency to ameliorate histopathological changes in the pancreas (10-100 mg/kg p.o.). 3. FUT-187 (10 mg/kg) produced an obvious improvement of various biochemical parameters of pancreatitis and also reduced histopathological changes in the pancreas in animals with experimental pancreatitis produced by the closed duodenal loop method. In addition, FUT-187 significantly increased the survival of dogs when given by direct administration into the lumen of the closed duodenal loop. The therapeutic effects of FUT-187 in experimental pancreatitis were nearly equal in most instances to those of camostat mesilate. Thus, FUT-187 would appear to be an effective new agent for the treatment of pancreatitis. 相似文献
985.
Previous studies have demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) both increases and decreases levels of 3'-azido-3'-deoxythymidine (AZT) nucleotides in certain human myeloid cells. The present studies have examined the effects of GM-CSF on AZT metabolism in U-937 cells. The results demonstrate that GM-CSF stimulated AZT nucleotide formation in these cells. This stimulation was detectable during concurrent exposure to GM-CSF and AZT or as a result of pretreatment with GM-CSF. The GM-CSF-induced enhancement in AZT nucleotide formation was associated with a 4-fold increase in AZT uptake. The finding that uptake of AZT into U-937 cells was only partially sensitive to 6-[(4-nitrobenzyl)thio]-9-beta-D-ribofuranosylpurine (NBMPR) suggested a process primarily involving nonfacilitated diffusion. The results also demonstrate that treatment of U-937 cells with GM-CSF was associated with nearly a 2-fold increase in thymidine kinase activity. Moreover, the findings indicate that retention of AZT-MP and AZP-TP was prolonged significantly (P less than 0.05 and P less than 0.01 respectively) in association with GM-CSF treatment. Taken together, these results suggest that GM-CSF enhances the formation of AZT nucleotides by increasing AZT uptake and phosphorylation, as well as increasing retention of phosphorylated derivatives. 相似文献
986.
Mycenon, a new metabolite from a Mycena species TA 87202 (basidiomycetes) as an inhibitor of isocitrate lyase 总被引:1,自引:0,他引:1
Mycenon (C11H5Cl3O3), a new inhibitor of isocitrate lyase (EC 4.1.3.1) was isolated from the culture broth of a basidiomycete, Mycena sp. Mycenon is a novel chlorinated benzoquinone derivative which is also active against bacteria and fungi. Malate synthase (EC 4.1.3.2) the second key enzyme of the glyoxylate cycle was not affected by mycenon. Isocitrate lyase preparations from plants, bacteria and fungi were sensitive. The following Ki-values for mycenon have been determined: Ricinus communis, 5.2 microM; Acinetobacter calcoaceticus, 11 microM; Neurospora crassa, 7.4 microM. The structure of mycenon has been determined by a single crystal X-ray analysis. 相似文献
987.
The effect of thymosin fraction 5 and its synthetic component thymosin-alpha 1 administered i. p. and i. c. v. on the behavior of 219 Wistar rats in the open field was studied to establish the effective dose and time of action of both substances. It was shown that at i. c. v. administration of both compounds in a dose of 10 ng the motor activity was suppressed for about 0.5 hour. At i. p. administration thymosin fraction 5 in doses of 0.15, 0.3 and 0.6 mg/kg suppressed the motor activity for more than 2 hours. The higher the dose, the greater the degree of suppression of the motor activity. Both peptides influence in a similar way the motor activity of the animals irrespective of the route of administration. 相似文献
988.
989.
Teaching psychiatric ethics 总被引:1,自引:0,他引:1
S Bloch 《Medical education》1988,22(6):550-553
In the last decade, we have witnessed a burgeoning of interest in ethical issues amongst psychiatrists. Teaching of the subject, however, remains at a rudimentary stage. Various approaches to such instruction are available, particularly modelling (students observe their experienced counterpart), the case method (examining specific clinical situations which involve a need for ethical decision-making), and the seminar approach (trainees are exposed to a core body of knowledge, mainly theoretical in nature). Faced with these different teaching models, the University of Oxford Department of Psychiatry has opted for a blend of all three approaches, which incorporates two goals: an increase in the trainees' sensitivity to the many intricate moral dilemmas facing the psychiatric profession; and their familiarity with salient concepts in moral philosophy which constitute a basis for ethical reasoning and which have a bearing on clinical practice. The teaching programme comprises the following: a pair of trainees prepares a presentation on an aspect of psychiatric ethics under the supervision of a senior psychiatrist. A moral philosopher assumes the role of discussant of the ethical problems raised by the trainees; this is followed by a general discussion. Topics have included involuntary hospitalization, dual loyalty, suicide, psychiatric diagnosis, and ethical issues in various spheres of psychiatric practice such as sex therapy, psychotherapy and child psychiatry. The approach has worked effectively and proved rewarding to all participants involved. 相似文献
990.
Multicentricity of hepatocellular carcinoma (HCC) is considered, especially in patients with liver cirrhosis. This paper describes an operative case of a male patient with probable multicentric development of HCC in precirrhotic fibrosis. The main tumors inside the capsule were completely necrotic due to transarterial embolization (TAE). Histologic examination disclosed discrete tiny nodules of HCC that were not detected grossly. They showed highly differentiated trabecular arrangements: Edmondson I. A scirrhous type was noted in the center of the tumors. At the borders of the tumors the carcinoma cells exhibited replacing growth patterns and it was thought that they developed multicentrically. Partial resection must be performed as extensively as possible in a case such as the present one. 相似文献