全文获取类型
收费全文 | 289617篇 |
免费 | 35772篇 |
国内免费 | 194篇 |
出版年
2016年 | 2786篇 |
2015年 | 4154篇 |
2014年 | 4845篇 |
2013年 | 6886篇 |
2012年 | 7755篇 |
2011年 | 7694篇 |
2010年 | 5288篇 |
2009年 | 4986篇 |
2008年 | 7004篇 |
2007年 | 7211篇 |
2006年 | 6841篇 |
2005年 | 6792篇 |
2004年 | 6610篇 |
2003年 | 6722篇 |
2002年 | 6393篇 |
2001年 | 11040篇 |
2000年 | 11155篇 |
1999年 | 9184篇 |
1998年 | 3558篇 |
1997年 | 3730篇 |
1996年 | 3715篇 |
1995年 | 3457篇 |
1994年 | 3458篇 |
1993年 | 3427篇 |
1992年 | 8169篇 |
1991年 | 7959篇 |
1990年 | 7755篇 |
1989年 | 7680篇 |
1988年 | 7245篇 |
1987年 | 7197篇 |
1986年 | 6662篇 |
1985年 | 6811篇 |
1984年 | 5710篇 |
1983年 | 5126篇 |
1982年 | 4092篇 |
1981年 | 3938篇 |
1980年 | 3573篇 |
1979年 | 5924篇 |
1978年 | 4635篇 |
1977年 | 4438篇 |
1976年 | 4235篇 |
1975年 | 4577篇 |
1974年 | 5036篇 |
1973年 | 4927篇 |
1972年 | 4585篇 |
1971年 | 4135篇 |
1970年 | 3643篇 |
1969年 | 3667篇 |
1968年 | 3270篇 |
1967年 | 2823篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Blood smears of both male and female chicken Gallus domesticus were analysed by using the following topochemical methods: a) Periodic acid-Schiff (PAS) for glycogen. b) Mercury-bromophenol blue for protein. c) O-Toluidine for myeloperoxidase. d) Sudan black B for lipid. The PAS reaction revealed glycogen in the cytoplasm of all thrombocytes and in a few heterophils. The presence of proteins was evidenced in all types of cells. However variation in the intensity of staining of protein granules was observed in the fusiform structures of the heterophils. A negative reaction for myeloperoxidase was found in all cells. Although some evidence of myeloperoxidase activity was show in the polymorphonuclears it was not enough to ascertain a positive reaction. Lipids were detected in the cytoplasm of few heterophils, eosinophils and monocytes. 相似文献
122.
Peak area matching and linear regression were used to quantify eight chlorinated pesticides and polychlorinated biphenyls (as Aroclor 1260) in human serum. There are no statistically significant differences in data obtained by these two quantifying techniques which were indicated by the paired t-test. For chlorinated pesticides, p = 0.053-0.62, and for polychlorinated biphenyls (as Aroclor 1260), p = 0.64. Analyte residues for the chlorinated pesticides ranged from 0.5 ppb for hexachlorobenzene (HCB) to 186 ppb for dichlorodiphenyldichloroethylene (DDE). Analyte residues for the polychlorinated biphenyls (as Aroclor 1260) ranged from 5-114 ppb. The absolute mean percent difference between the two quantifying techniques ranged from 0.06% for DDE to 8.06% for dieldrin (HEOD) among the chlorinated pesticides. The absolute mean percent difference between the two quantifying techniques for the polychlorinated biphenyls (as Aroclor 1260) was 3.4%. Peak area matching and linear regression were found to be comparable for quantifying these environmental residues in serum when the following conditions apply: 1) the concentration of the chlorinated pesticides is greater than or equal to 0.5 ppb (e.g., HCB, hexachlorocyclohexane (HCCH), oxychlordane (OC), heptachlor epoxide (HE), transnonachlor (TN), HEOD, and dichlorodiphenyltrichloroethane (DDT); 2) the concentration of the chlorinated pesticide is greater than or equal to 3 ppb (e.g., DDE); and 3) the total concentration of polychlorinated biphenyls (e.g., as Aroclor 1260) is greater than or equal to 5 ppb. 相似文献
123.
124.
125.
126.
127.
128.
W.-E. Kalisch 《Genetica》1982,60(1):21-24
Electron micrographs as well as light micrographs of individual surface-spread polytene (SSP) chromosomes indicate more detailed banding patterns than standard squash preparations do. For EM preparations of SSP chromosomes a simple technique is described, avoiding thin-sectioning of chromosomes. 相似文献
129.
130.
Ten healthy middle-aged women volunteered for a study to test the effect of lactulose--a synthetic, non-absorbable disaccharide--on the colonic metabolism of bile acids and on bile lipid composition. Lactulose (60 g daily in eight cases, 39 g daily in two) was taken as a proprietary syrup for six weeks, and bile was collected by duodenal intubation before and immediately after six weeks. All subjects showed a fall in the percentage of the 7-alpha-dehydroxylated bile acid deoxycholic acid (mean 28.4 +/- SEM 3.7 to 15.6 +/- 2.4; p less than 0.002) and a rise in the percentage of the primary bile acid chenodeoxycholic acid (mean 33.2 +/- 42.9 +/- 2.9; p less than 0.001). The percentage of cholic acid rose in eight subjects but mean values did not differ significantly. Bile was initially super-saturated with cholesterol in most subjects and became less saturated with cholesterol in all but one (mean saturation index 1.40 +/- 0.11 to 1.19 +/- 0.07; p less these 0.005). These data support the theory colonic bacteria contribute to cholesterol gall-stone formation. 相似文献