全文获取类型
收费全文 | 2994358篇 |
免费 | 236566篇 |
国内免费 | 5155篇 |
专业分类
耳鼻咽喉 | 43508篇 |
儿科学 | 89154篇 |
妇产科学 | 78637篇 |
基础医学 | 422785篇 |
口腔科学 | 88152篇 |
临床医学 | 270543篇 |
内科学 | 584505篇 |
皮肤病学 | 61407篇 |
神经病学 | 247305篇 |
特种医学 | 119167篇 |
外国民族医学 | 941篇 |
外科学 | 461670篇 |
综合类 | 68288篇 |
现状与发展 | 2篇 |
一般理论 | 1156篇 |
预防医学 | 232789篇 |
眼科学 | 70601篇 |
药学 | 227373篇 |
7篇 | |
中国医学 | 5868篇 |
肿瘤学 | 162221篇 |
出版年
2018年 | 29801篇 |
2016年 | 25516篇 |
2015年 | 28893篇 |
2014年 | 41197篇 |
2013年 | 62334篇 |
2012年 | 84233篇 |
2011年 | 88811篇 |
2010年 | 52372篇 |
2009年 | 50163篇 |
2008年 | 84978篇 |
2007年 | 90077篇 |
2006年 | 91435篇 |
2005年 | 88995篇 |
2004年 | 85801篇 |
2003年 | 82700篇 |
2002年 | 81615篇 |
2001年 | 145845篇 |
2000年 | 151090篇 |
1999年 | 127565篇 |
1998年 | 34951篇 |
1997年 | 31551篇 |
1996年 | 31371篇 |
1995年 | 30174篇 |
1994年 | 28329篇 |
1993年 | 26310篇 |
1992年 | 101949篇 |
1991年 | 98364篇 |
1990年 | 95015篇 |
1989年 | 91945篇 |
1988年 | 84998篇 |
1987年 | 83384篇 |
1986年 | 78825篇 |
1985年 | 75373篇 |
1984年 | 56242篇 |
1983年 | 47960篇 |
1982年 | 28005篇 |
1981年 | 24827篇 |
1980年 | 23207篇 |
1979年 | 52144篇 |
1978年 | 36248篇 |
1977年 | 30773篇 |
1976年 | 28309篇 |
1975年 | 30243篇 |
1974年 | 37201篇 |
1973年 | 35288篇 |
1972年 | 33189篇 |
1971年 | 30868篇 |
1970年 | 29085篇 |
1969年 | 27222篇 |
1968年 | 24713篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Excretory/secretory antigen of Toxocara canis: recognition profiles of polyclonal and larvicidal monoclonal antibodies 总被引:1,自引:1,他引:0
Summary Five monoclonal antibodies against the excretory/secretory (E/S) antigen of Toxocara canis were obtained and characterized. Immunoprecipitating activity was demonstrated in an in-vitro micropre-cipitating assay using live T. canis larvae. Their capacity to kill larvae was also shown in an in-vitro assay. Two zones of reactivity were observed in 7.5 and 12.5% SDS-PAGE (177-77 kD, 43-15 kD) of immunoprecipitates of human and mouse positive polyclonal anlisera. The murine monoclonal antibodies showed a common pattern of reactivity with the proteins in the 177-77 kD range. 相似文献
952.
Tissue-specific regulation of pyroglutamate aminopeptidase II activity by thyroid hormones 总被引:2,自引:0,他引:2
Among the enzymes capable of degrading thyrotropin-releasing hormone (TRH) in vitro, two pyroglutamate aminopeptidases (PGA) are specific for TRH: thyroliberinase, a seric enzyme and PGAII, a membrane-bound peptidase. The effect of thyroid hormone status on the activity of these enzymes was evaluated in serum and various tissues. Only in adenohypophysis, triiodothyronine treatment increased PGAII to 376% of control; hypothyroidism produced the reverse effect (decrease to 23% of control). As previously reported, similar changes were observed for thyroliberinase. TRH degradation at the adenohypophysis level may participate in the negative feedback control of thyroid hormones. 相似文献
953.
B. Ehlers E. Strauch M. Goltz D. Kubsch H. Wagner H. Maidhof J. Bendiek B. Appel H. -J. Buhk 《Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz》1997,40(4):118-121
Zusammenfassung Ein PCR-Nachweis für gentechnisch ver?nderten Mais ?Event 176? der Fa. Ciba-Geigy wurde etabliert. Der Mais enth?lt Gene,
die Selbstschutz gegen den Maiszünsler (Delta-Endotoxin-Gen ausBacillus thuringiensis) und Toleranz gegen das Herbizid Basta (Phosphinothricin-Resistenz-Gen ausStreptomyces hygroscopicus) vermitteln. Zudem enth?lt der Mais ein Ampicillin-Resistenz-Gen. Für die Amplifikation von Bereichen aus allen drei Genen
wurden PCR-Primer entworfen. Mit Hilfe dieser Primer und mit ?Event 176?-Mais-DNA als Template konnten die entsprechenden
Genbereiche in der PCR amplifiziert werden. Die PCR-Produkte wurden sequenziert, um ihre Identit?t zu best?tigen. Mit Hilfe
der Delta-Endotoxin-PCR wurden, auch in Gegenwart von 104fachem überschu? nicht gentechnisch ver?nderter Mais-DNA, fünf haploide Genome der ?Event 176?-DNA nachgewiesen.
Identification of genetically modified maize by PCR
Summary A PCR-test for the genetically modified maize ?Event 176? of Ciba-Geigy was established. The maize contains genes conferring resistance to the European corn borer (delta-endotoxin gene fromBacillus thuringiensis) and tolerance to the herbicide Basta (phosphinothricin resistance gene fromStreptomyces hygroscopicus). The maize contains also an ampicillin resistance gene. Primers were designed and using ?Event 176?-maize-DNA as template internal regions of the three genes were amplified with PCR. The PCR products were sequenced to confirm their identity. Using the deltaendotoxin primers in PCR down to 5 haploid genomes of ?Event 176?-DNA could be detected, even in the presence of a 104fold excess of DNA from non-modified maize.相似文献
954.
P. THOMPSON F. INGLIS D. FINDLAY J. GILCHRIST M. E. T. MCMURDO 《Aging & mental health》1997,1(2):181-183
The Dundee Memory Clinic was established in 1991. This paper reviews the diagnosis of the first 150 attenders and compares the findings with those of other memory clinics. 相似文献
955.
A reduction in sources of environmental lead exposure has resulted in substantial declines in mean blood lead concentrations of all age groups in the United States. However, some segments of the population continue to have unacceptable levels of lead exposure and elevated blood lead concentrations. In addition, virtually all residents of industrialized countries have bone lead stores that are several orders of magnitude greater than those of our preindustrial ancestors. Recent studies suggest that these skeletal lead stores adversely affect health and can contribute to reduced birth weights, aggressive behavior in children, and anemia, hypertension, and kidney disease in adults. Evidence is described that demonstrates that an increase in dietary calcium consumption can reduce lead absorption and toxicity from exogenous and endogenous lead exposure. A relatively inexpensive and effective way to reduce the substantial morbidity that will result from widespread lead exposure is by fortification of a variety of foods with low levels of calcium. This approach can complement other efforts to prevent lead exposure and reduce lead toxicity. 相似文献
956.
957.
J. R. Martin 《Autonomic & autacoid pharmacology》1997,17(4):249-259
1 Intravenous administration of the ganglionic nicotinic receptor agonist DMPP (1,1-dimethyl-4-phenylpiperazinium iodide) into urethane-anaesthetized rats evoked dose-dependent increases in mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). 2 The ganglionic nicotinic receptor antagonists pentolinium and hexamethonium either alone or combined did not inhibit the increase in RSNA and MAP evoked by 50 to 200 μg kg?1 doses of DMPP. The increase in renal sympathetic nerve activity evoked by DMPP occurred as a brief burst in firing. 3 The increase in MAP, but not RSNA, evoked by DMPP in the presence of pentolinium was inhibited by the selective α1-adrenergic receptor antagonist prazosin. 4 The non-selective α-adrenoceptor and NPY receptor antagonist benextramine also inhibited the increase in MAP without inhibiting the increase in RSNA. Surprisingly, the combination of benextramine and pentolinium, or benextramine and hexamethonium, completely blocked the DMPP-evoked increase in RSNA and thus the increase in MAP. 5 The uptake1 antagonist desipramine combined with pentolinium did not affect the DMPP-evoked increases in MAP or RSNA when compared to the responses evoked in the presence of pentolinium alone. 6 Adding the selective M1 muscarinic receptor antagonist telenzepine to pentolinium and prazosin did not inhibit the increase in RSNA evoked by a 100 μg kg?1 dose of DMPP. 7 While the DMPP-evoked increase in MAP in the presence of ganglionic nicotinic receptor antagonists is primarily dependent upon activation of α1-adrenoceptors, the increase in RSNA occurs via activation of ganglionic nicotinic receptors and activation of a mechanism susceptible to blockade by benextramine. 相似文献
958.
959.
960.