全文获取类型
收费全文 | 6364篇 |
免费 | 597篇 |
国内免费 | 1篇 |
出版年
2021年 | 61篇 |
2019年 | 57篇 |
2018年 | 56篇 |
2017年 | 56篇 |
2016年 | 93篇 |
2015年 | 182篇 |
2014年 | 226篇 |
2013年 | 286篇 |
2012年 | 343篇 |
2011年 | 362篇 |
2010年 | 271篇 |
2009年 | 202篇 |
2008年 | 289篇 |
2007年 | 327篇 |
2006年 | 308篇 |
2005年 | 275篇 |
2004年 | 282篇 |
2003年 | 301篇 |
2002年 | 244篇 |
2001年 | 140篇 |
2000年 | 116篇 |
1999年 | 125篇 |
1998年 | 103篇 |
1997年 | 65篇 |
1996年 | 80篇 |
1995年 | 66篇 |
1994年 | 70篇 |
1993年 | 69篇 |
1992年 | 81篇 |
1991年 | 90篇 |
1990年 | 85篇 |
1989年 | 55篇 |
1988年 | 87篇 |
1987年 | 52篇 |
1986年 | 53篇 |
1985年 | 76篇 |
1984年 | 64篇 |
1983年 | 50篇 |
1982年 | 60篇 |
1981年 | 54篇 |
1980年 | 49篇 |
1979年 | 48篇 |
1977年 | 54篇 |
1976年 | 43篇 |
1975年 | 38篇 |
1974年 | 50篇 |
1972年 | 45篇 |
1971年 | 35篇 |
1969年 | 37篇 |
1968年 | 38篇 |
排序方式: 共有6962条查询结果,搜索用时 265 毫秒
221.
222.
Larry A. Jones Diane K. Jordan Kutay Taysi Arnold W. Strauss Joseph K. Toth 《Human genetics》1979,51(1):37-42
Summary A partial duplication of the distal segment of the long arm of chromosome 5 (q31qter) was observed in an infant with congenital malformations and dysmorphic features. The phenotypically normal father had a balanced translocation between the long arm of chromosome 5 and the short arm of chromosome 9: 46,XY,t(5;9)(q31;p24).The clinical and cytogenetic data obtained from six patients with partial duplications of two different long arm segments of chromosome 5 suggest that partial duplication of the distal long arm of chromosome 5 is associated with microcephaly, hypertelorism, epicanthus, strabismus, large upper lip, low-set, dysplastic ears, in addition to growth and psychomotor retardation. Partial duplication of the proximal part of the long arm of chromosome 5, on the other hand, is associated mainly with musculoskeletal abnormalities including muscle hypotrophy and hypotonia, scoliosis, lordosis, pectus carinatum, cubitus valgus, and genu valgum, in addition to psychomotor retardation. The dysmorphic features in this latter group include a bulging forehead, short nose, thick upper lip, low-set protruding ears and tapering, thin fingers. 相似文献
223.
224.
1-Hexadecylpropanediol-3-phosphorylcholine, an ether-deoxy analog of lysophosphatidylcholine, has been employed to study the sensitivity of various types of mouse cells with respect to changes in membrane permeability induced by lysophosphatidylcholine. Cells used included erythrocytes, thymocytes, spleen cells and macrophage, as well as 4 different tumors (2 lymphomas, 1 Ehrlich acites and 1 methylcholanthren-induced fibrosarcoma). The sensitivity to the lysophosphatide (on a per-cell basis) of the above cell types varied by a factor of 65. When lytic concentrations were related to available membrane surface, this variation was reduced to a factor of 2.5. No principal difference was observed between the sensitivity of normal versus tumor cell membranes with respect to lysophosphatidylcholine lysis. Membrane surface, available for lysophosphatidylcholine, has been estimated from binding equilibria of 14C-labelled deoxy-lysophosphatidylcholine to the cells under standardized conditions. This method is based on the finding that binding equilibria of lysophospholipids to cells are predominantly determined by the available membrane surface. 相似文献
225.
226.
Administration of sodium salicylate (50–500 mg/kg, i.p.) reduced serum insulin concentrations in nonfasted rats. This treatment also suppressed the rise in serum insulin that followed oral administration of glucose (by stomach tube) to fasted rats; this effect is only partly attributable to the blunted increase in serum glucose concentrations. 相似文献
227.
228.
229.
B M Arnold M Kuttner R Swaminathan A D Care A J Hitchman J E Harrison T M Murray 《Canadian journal of physiology and pharmacology》1975,53(6):1129-1134
We have developed a radioimmunoassay for porcine intestinal calcium-binding protein (CaBP) and have used it to detect CaBP in pig plasma. Plasma CaBP is identical to intestinal CaBP on the basis of immunological activity, molecular size, and molecular charge properties. The plasma CaBP concentration was greater in the portal blood than in mixed venous blood, suggesting that blood CaBP originates in the gut. Two of four 15-week-old littermate pigs were placed on a low calcium diet (0.15% calcium, 0.65% phosphorus) and two on a control diet (0.65% calcium, 0.65% phosphorus). After 2 weeks, the entire small intestine was removed and divided into nine 1.8-m segments. CaBP was assayed in both plasma and intestinal mucosa. When the two pigs on a low calcium diet were compared with two control pigs, there was a general increase in immunoreactive CaBP in both plasma and intestinal mucosa. However, there was no increment in immunoreactive CaBP in the first 1.8-m segment of small intestine. Seventy-one percent of the increment in CaBP occurred distal to the first two segments. The largest fractional low calcium diet effect occurred in the ileum. The mean CaBP concentration for the total small intestine increased by a factor of 1.9. The plasma CaBP concentration increased by a factor of 2.6. In these pigs, plasma CaBP was a more reliable indicator of change in CaBP status than was the measurement in the proximal gut segment which contained the duodenum. The assay of CaBP in blood is convenient and may obviate the sampling errors inherent in intestinal biopsy. 相似文献
230.