全文获取类型
收费全文 | 796342篇 |
免费 | 82455篇 |
国内免费 | 249篇 |
专业分类
879046篇 |
出版年
2018年 | 7929篇 |
2017年 | 7580篇 |
2016年 | 10630篇 |
2015年 | 13443篇 |
2014年 | 16021篇 |
2013年 | 23123篇 |
2012年 | 25963篇 |
2011年 | 26747篇 |
2010年 | 18265篇 |
2009年 | 16885篇 |
2008年 | 23908篇 |
2007年 | 24875篇 |
2006年 | 23252篇 |
2005年 | 22361篇 |
2004年 | 22138篇 |
2003年 | 21298篇 |
2002年 | 20808篇 |
2001年 | 34733篇 |
2000年 | 34194篇 |
1999年 | 27568篇 |
1998年 | 10176篇 |
1997年 | 10263篇 |
1996年 | 9838篇 |
1995年 | 9057篇 |
1994年 | 8720篇 |
1993年 | 8751篇 |
1992年 | 22333篇 |
1991年 | 21916篇 |
1990年 | 21368篇 |
1989年 | 20812篇 |
1988年 | 19079篇 |
1987年 | 18321篇 |
1986年 | 17091篇 |
1985年 | 16952篇 |
1984年 | 13933篇 |
1983年 | 12181篇 |
1982年 | 9230篇 |
1981年 | 8355篇 |
1980年 | 7753篇 |
1979年 | 12938篇 |
1978年 | 10201篇 |
1977年 | 9191篇 |
1976年 | 8802篇 |
1975年 | 9816篇 |
1974年 | 10484篇 |
1973年 | 10350篇 |
1972年 | 9477篇 |
1971年 | 8456篇 |
1970年 | 7384篇 |
1969年 | 7255篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
7.
A. A. Kepel' 《Russian Journal of Marine Biology》2000,26(6):450-452
The alga Analipus japonicus (Harv.) Wynne displays a distinct seasonal pattern in its development in Peter the Great Bay (Sea of Japan). In winter and spring, it occurs only in the form of basal crusts, and vertical axes develop in the summer–autumn period. It reproduces mostly asexually from July to November. Algae with unilocular sporangia occur very seldom, only in June and July. 相似文献
8.
Genetic analysis of sterile mutants in the dpy-5 unc-13 (I) genomic region of Caenorhabditis elegans
Essential genes were identified in the 1.5-map unit dpy-5 unc-13 region of chromosome I in the Caenorhabditis elegans genome by rescuing lethal mutations using the duplication sDp2. In this paper, we report the mapping and complementation testing of lethal mutations, 45 of which identify 18 new, essential
genes. This analysis brings the number of essential genes defined by the sDp2 rescue of lethal mutants to 97; 64 of these map between dpy-5 and unc-13. 61% of these essential genes are identified by more than one allele. Positioning of the mutations was done using the breakpoints
of six duplications. The mutant phenotypes of 14 loci essential for fertility were characterized by Nomarski microscopy and
DAPI staining. None of the mutants were rescued by wild-type male sperm. The cytological data showed that four genes produced
mutants with defects in gonadogenesis, let-395, let-603, let-605 and let-610. Mutations in seven genes, let-355, let-367, let-384, let-513, let-544, let-545 and let-606, affected germ cell proliferation or gametogenesis. Mutants for the remaining three genes, let-370, let-599 and let-604, produced eggs that failed to develop or hatch, thereby acting as maternal effect lethals. We observed a nonrandom distribution
of arrest phenotypes with regard to map position.
Received: 8 May 1996 / Accepted : 27 January 1997 相似文献
9.
10.
Based on its proven anabolic effects on bone in osteoporosis patients, recombinant parathyroid hormone (PTH1-34) has been evaluated as a potential therapy for skeletal repair. In animals, the effect of PTH1-34 has been investigated in various skeletal repair models such as fractures, allografting, spinal arthrodesis and distraction
osteogenesis. These studies have demonstrated that intermittent PTH1-34 treatment enhances and accelerates the skeletal repair process via a number of mechanisms, which include effects on mesenchymal
stem cells, angiogenesis, chondrogenesis, bone formation and resorption. Furthermore, PTH1-34 has been shown to enhance bone repair in challenged animal models of aging, inflammatory arthritis and glucocorticoid-induced
bone loss. This pre-clinical success has led to off-label clinical use and a number of case reports documenting PTH1-34 treatment of delayed-unions and non-unions have been published. Although a recently completed phase 2 clinical trial of PTH1-34 treatment of patients with radius fracture has failed to achieve its primary outcome, largely because of effective healing
in the placebo group, several secondary outcomes are statistically significant, highlighting important issues concerning the
appropriate patient population for PTH1-34 therapy in skeletal repair. Here, we review our current knowledge of the effects of PTH1-34 therapy for bone healing, enumerate several critical unresolved issues (e.g., appropriate dosing regimen and indications)
and discuss the long-term potential of this drug as an adjuvant for endogenous tissue engineering. 相似文献