全文获取类型
收费全文 | 91750篇 |
免费 | 2838篇 |
国内免费 | 47篇 |
专业分类
94635篇 |
出版年
2018年 | 1057篇 |
2017年 | 1250篇 |
2016年 | 2988篇 |
2015年 | 6325篇 |
2014年 | 5963篇 |
2013年 | 5813篇 |
2012年 | 5231篇 |
2011年 | 2486篇 |
2010年 | 2378篇 |
2009年 | 2271篇 |
2008年 | 1044篇 |
2007年 | 969篇 |
2006年 | 969篇 |
2005年 | 7001篇 |
2004年 | 5744篇 |
2003年 | 3898篇 |
2002年 | 1444篇 |
2001年 | 1363篇 |
2000年 | 584篇 |
1999年 | 1643篇 |
1998年 | 446篇 |
1994年 | 263篇 |
1992年 | 2020篇 |
1991年 | 2095篇 |
1990年 | 2156篇 |
1989年 | 2066篇 |
1988年 | 2019篇 |
1987年 | 1877篇 |
1986年 | 1689篇 |
1985年 | 1734篇 |
1984年 | 1179篇 |
1983年 | 903篇 |
1982年 | 536篇 |
1981年 | 480篇 |
1980年 | 437篇 |
1979年 | 1124篇 |
1978年 | 821篇 |
1977年 | 653篇 |
1976年 | 676篇 |
1975年 | 922篇 |
1974年 | 1037篇 |
1973年 | 1054篇 |
1972年 | 969篇 |
1971年 | 961篇 |
1970年 | 839篇 |
1969年 | 857篇 |
1968年 | 751篇 |
1967年 | 762篇 |
1966年 | 593篇 |
1965年 | 438篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
96.
97.
The use of the artificial antigen abequosylmannoside copolymer with acrylamide in the enzyme immunoassay for the determination of antibodies in the sera of salmonellosis patients has enhanced the specificity of the serological diagnosis of group B salmonellosis in comparison with the use of the natural antiren, S. typhimurium lipopolysaccharide. 相似文献
98.
I Monta?és A Badía M A Réngel J M López-Novoa 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1992,199(3):321-326
Renal metabolism has been studied in eight dogs before and 48 hr after a 60-min period of renal ischemia induced by clamping the left renal artery with the simultaneous removal of the right kidney, and in 12 sham-operated animals. The study involved the measurement of renal uptake and production of lactate, glutamine, glutamate, alanine, ammonium, and oxygen, and the measurement of the tissue concentrations of ATP, glutamine, lactate, alpha-ketoglutarate, aspartate, and alanine in the renal cortex. Two days after a temporary renal ischemia, the remaining kidney showed a 22% decrease in glomerular filtration rate (GFR) and a 25% decrease in renal plasma flow. Fractional sodium and potassium excretions were similar to those of control dogs. Renal production or extraction of glutamine, glutamate, alanine, ammonium, and oxygen (all expressed by 100 ml of GFR) was not significantly different in basal conditions or 2 days after ischemia, but lactate extraction was reduced in postischemic kidneys (-101 +/- 29 vs -204 +/- 38 mumol/100 ml GFR in control dogs). The cortical concentrations of glutamine and glutamate were lower in postischemic than in control kidneys. No differences were found in cortical concentration of alpha-ketoglutarate, aspartate, lactate, pyruvate, or ATP, but total nucleotides and inorganic phosphate were decreased in postischemic kidneys. It is concluded that in the recovery phase of the ischemia, a decreased lactate uptake is the main metabolic change, and total ATP production is adapted to the decrease of GFR and sodium reabsorption. 相似文献
99.
New class I and II HLA alleles strongly associated with opposite patterns of progression to AIDS. 总被引:10,自引:0,他引:10
H Hendel S Caillat-Zucman H Lebuanec M Carrington S O'Brien J M Andrieu F Sch?chter D Zagury J Rappaport C Winkler G W Nelson J F Zagury 《Journal of immunology (Baltimore, Md. : 1950)》1999,162(11):6942-6946
The genetics of resistance to infection by HIV-1 cohort consists of 200 slow and 75 rapid progressors to AIDS corresponding to the extremes of HIV disease outcome of 20,000 Caucasians of European descent. A comprehensive analysis of HLA class I and class II genes in this highly informative cohort has identified HLA alleles associated with fast or slow progression, including several not described previously. A quantitative analysis shows an overall HLA influence independent of and equal in magnitude (for the protective effect) to the effect of the CCR5-Delta32 mutation. Among HLA class I genes, A29 (p = 0.001) and B22 (p < 0.0001) are significantly associated with rapid progression, whereas B14 (p = 0.001) and C8 (p = 0.004) are significantly associated with nonprogression. The class I alleles B27, B57, C14 (protective), and C16, as well as B35 (susceptible), are also influential, but their effects are less robust. Influence of class II alleles was only observed for DR11. These results confirm the influence of the immune system on disease progression and may have implications on peptide-based vaccine development. 相似文献
100.
R H?kanson D Chen E Lindstr?m P Norlén M Bj?rkqvist D Lehto-Axtelius 《The Yale journal of biology and medicine》1998,71(3-4):163-171
The enterochromaffin-like (ECL) cells of the oxyntic mucosa (fundus) of the stomach produce, store and secrete histamine, chromogranin A-derived peptides such as pancreastatin, and an unanticipated but as yet unidentified peptide hormone. The cells are stimulated by gastrin and pituitary adenylate cyclase activating peptide and suppressed by somatostatin and galanin. Choline esters and histamine seem to be without effect on ECL cell secretion. The existence of a gastrin-ECL cell axis not only explains how gastrin stimulates acid secretion but also may help to explore the functional significance of the ECL cells with respect to the nature and bioactivity of its peptide hormone. From the results of studies of gastrectomized/fundectomized and gastrin-treated rats, it has been speculated that the anticipated ECL-cell peptide hormone acts on bone metabolism. 相似文献