全文获取类型
收费全文 | 17471篇 |
免费 | 25篇 |
国内免费 | 67篇 |
专业分类
系统科学 | 124篇 |
丛书文集 | 288篇 |
教育与普及 | 44篇 |
理论与方法论 | 76篇 |
现状及发展 | 7464篇 |
研究方法 | 941篇 |
综合类 | 8363篇 |
自然研究 | 263篇 |
出版年
2013年 | 119篇 |
2012年 | 311篇 |
2011年 | 578篇 |
2010年 | 109篇 |
2009年 | 102篇 |
2008年 | 322篇 |
2007年 | 378篇 |
2006年 | 383篇 |
2005年 | 386篇 |
2004年 | 389篇 |
2003年 | 333篇 |
2002年 | 327篇 |
2001年 | 613篇 |
2000年 | 572篇 |
1999年 | 390篇 |
1992年 | 327篇 |
1991年 | 265篇 |
1990年 | 280篇 |
1989年 | 255篇 |
1988年 | 236篇 |
1987年 | 280篇 |
1986年 | 291篇 |
1985年 | 321篇 |
1984年 | 282篇 |
1983年 | 223篇 |
1982年 | 184篇 |
1981年 | 195篇 |
1980年 | 250篇 |
1979年 | 566篇 |
1978年 | 435篇 |
1977年 | 427篇 |
1976年 | 314篇 |
1975年 | 351篇 |
1974年 | 517篇 |
1973年 | 438篇 |
1972年 | 429篇 |
1971年 | 524篇 |
1970年 | 689篇 |
1969年 | 487篇 |
1968年 | 402篇 |
1967年 | 490篇 |
1966年 | 399篇 |
1965年 | 282篇 |
1959年 | 162篇 |
1958年 | 268篇 |
1957年 | 207篇 |
1956年 | 180篇 |
1955年 | 144篇 |
1954年 | 150篇 |
1948年 | 126篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
3.
4.
5.
6.
Obese postmenopausal female volunteers were given timed daily oral dosages of bromocriptine, and tested for reduction of body fat stores. This dopamine agonist has been shown to reset circadian rhythms that are altered in obese animals and to reduce body fat levels in several animal models. The participants were instructed not to alter their existing exercise and eating behavior during treatment. Skinfold measurements were taken on 33 subjects as indices of body fat. The measurements (e.g., suprailiac) were reduced after six weeks by about 25%, which represents a reduction of 11.7% of the total body fat. These dramatic decreases in body fat, which are equivalent to that produced by severe caloric restriction, were accompanied by more modest reductions of body weight (2.5%), indicating a possible conservation of protein that is usually lost as a consequence of such caloric restriction. The effects of bromocriptine treatment on body fat and hyperglycemia were also examined in non-insulin dependent diabetics being treated with oral hypoglycemics (7 subjects) or insulin (7 subjects). Total body fat was reduced by 10.7% and 5.1% in diabetics on oral hypoglycemics and insulin, respectively, without any significant reductions in body weight. Hyperglycemia was reduced in most of the 15 diabetic subjects treated leading to euglycemia and even cessation of hypoglycemic drugs in 3 of the 7 subjects during 4-8 weeks of bromocriptine treatment. These findings support the hypothesis that obesity and type II diabetes may be treated effectively with bromocriptine when administered at the proper times and dosages. 相似文献
7.
We recently reported on a linkage study within a Quarter Horse lineage segregating hyperkalaemic periodic paralysis (HYPP), an autosomal dominant condition showing potassium-induced attacks of skeletal muscle paralysis. HYPP co-segregated with the equine adult skeletal muscle sodium channel alpha subunit gene, the same gene that causes human HYPP. We now describe the Phe to Leu mutation in transmembrane domain IVS3 which courses the horse disease. This represents the first application of molecular genetics to an important horse disease, and the data will provide an opportunity for control or eradication of this condition. 相似文献
8.
就近几年图书馆界关于新世纪馆员意识转换及社会角色转换等方面的研究进行了综述,指出新时期的馆员要实现自我社会角色的转换,首先是要明确转换的必要性,然后采取有效的策略逐步地、系统地推进转换,才能取得较好的效果。 相似文献
9.
C. Ambrogi Lorenzini C. Bucherelli A. Giachetti G. Tassoni 《Cellular and molecular life sciences : CMLS》1991,47(10):1019-1026
Several aspects of spontaneous and conditioned behavior (food and water intake, locomotion and emotionality, passive and active avoidance acquisition and retention) of standard (albino and pigmented) rats, and rats heterozygous (HEDI) and homozygous (HODI) for diabetes insipidus, are reviewed. As would be expected, HODI rats have been repeatedly found to consume far more fluid than either HEDI or control rats. Pigmented rats appear to be more active than albinos. HODI rats exhibit less marked emotional responses than do control rats, among which the pigmented ones exhibit the highest emotionality. Light aversion is more evident in albino than in pigmented rats. No differences are found among HEDI, HODI and normal Long Evans rats. It is quite difficult to provide a clear-cut statement concerning inter-strain differences in passive avoidance behavior, possibly because of the variety of techniques employed. In any case, HODI rats do not perform worse than normal controls do. In one-way active avoidance paradigms, pigmented rats perform better than albinos, and the performance of HODI rats does not differ from that of controls. In two-way avoidance paradigms, albinos appear to outperform pigmented rats. Once again, there are no obvious differences between HODI and control animals.In addition to indicating that HODI rats may actually be less emotional than the other groups of rats reviewed here, the studies described once again fail to confirm the previously alleged functions of vasopressin in memory consolidation. 相似文献
10.
The genetic engineering of production traits in domestic animals 总被引:1,自引:0,他引:1