全文获取类型
收费全文 | 15271篇 |
免费 | 1375篇 |
国内免费 | 7篇 |
出版年
2021年 | 183篇 |
2020年 | 109篇 |
2019年 | 168篇 |
2018年 | 152篇 |
2017年 | 136篇 |
2016年 | 293篇 |
2015年 | 497篇 |
2014年 | 549篇 |
2013年 | 773篇 |
2012年 | 909篇 |
2011年 | 921篇 |
2010年 | 592篇 |
2009年 | 555篇 |
2008年 | 782篇 |
2007年 | 819篇 |
2006年 | 719篇 |
2005年 | 777篇 |
2004年 | 771篇 |
2003年 | 701篇 |
2002年 | 686篇 |
2001年 | 194篇 |
2000年 | 184篇 |
1999年 | 185篇 |
1998年 | 197篇 |
1997年 | 143篇 |
1996年 | 141篇 |
1995年 | 117篇 |
1994年 | 118篇 |
1993年 | 113篇 |
1992年 | 147篇 |
1991年 | 148篇 |
1990年 | 137篇 |
1989年 | 125篇 |
1988年 | 126篇 |
1987年 | 120篇 |
1986年 | 114篇 |
1985年 | 113篇 |
1984年 | 146篇 |
1983年 | 132篇 |
1982年 | 147篇 |
1981年 | 153篇 |
1980年 | 159篇 |
1979年 | 145篇 |
1978年 | 131篇 |
1977年 | 129篇 |
1976年 | 106篇 |
1975年 | 111篇 |
1974年 | 119篇 |
1973年 | 105篇 |
1969年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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
2.
Synthesis of prenylquinones in chloroplasts 总被引:3,自引:0,他引:3
3.
4.
Escherichia coli RecBC pseudorevertants lacking chi recombinational hotspot activity 总被引:24,自引:7,他引:17
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pseudorevertants of an Escherichia coli exonuclease V (RecBC enzyme)-negative mutant have been isolated after ethyl methane sulfonate mutagenesis of a recC73 (presumed missense) mutant. The remedial mutations in each of the four pseudorevertants studied in detail map and complement as recC mutations. By several criteria, such as recombination proficiency, support of phage growth, RecBC nuclease activity, and cell viability, the pseudorevertants appear to have regained partially or completely various aspects of RecBC activity. However, chi recombinational hotspots, which stimulate exclusively the RecBC pathway of recombination, have no detectable activity in lambda vegetative crosses in the pseudorevertants. The properties of these mutants, in which the RecBC pathway of recombination is active yet in which chi is not active, are consistent with the hypothesis that wild-type RecBC enzyme directly interacts with chi sites; alternatively, the mutants may block or bypass the productive interaction of another recombinational enzyme with chi. 相似文献
5.
6.
Edward Harrison 《BMJ (Clinical research ed.)》1916,1(2888):645-647
7.
Transcriptional regulatory network triggered by oxidative signals configures the early response mechanisms of japonica rice to chilling stress 总被引:3,自引:0,他引:3
8.
9.
10.